Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 30, 2013	Oct. 31, 2013
Document and Entity Information
Entity Registrant Name	Onconova Therapeutics, Inc.
Entity Central Index Key	0001130598
Document Type	10-Q
Document Period End Date	Sep. 30, 2013
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		21,410,905
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q3

Condensed Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 76,612,000	$ 81,527,000
Marketable securities	39,990,000
Prepaid expenses and other current assets	5,326,000	1,725,000
Total current assets	121,928,000	83,252,000
Property and equipment, net	652,000	463,000
Restricted cash	125,000	125,000
Other non-current assets	12,000	12,000
Total assets	122,717,000	83,852,000
Current liabilities:
Accounts payable	4,405,000	5,517,000
Accrued expenses and other current liabilities	7,817,000	3,925,000
Warrant liability	81,000	62,000
Option liability		11,967,000
Deferred revenue	2,530,000	3,907,000
Total current liabilities	14,833,000	25,378,000
Deferred revenue, non-current	14,023,000	15,421,000
Other	30,000	44,000
Total liabilities	28,886,000	40,843,000
Commitments and contingencies
Redeemable convertible preferred stock, $0.01 par value per share, none and 18,548,253 shares authorized at September 30, 2013 and December 31, 2012, none and 16,912,199 issued and outstanding at September 30, 2013 and December 31, 2012		201,315,000
Stockholders' equity (deficit):
Preferred stock, $0.01 par value, 5,000,000 and none authorized at September 30, 2013 and December 31, 2012, none issued and outstanding at September 30, 2013 and December 31, 2012
Common stock, $0.01 par value, 75,000,000 and 30,145,155 authorized at September 30, 2013 and December 31, 2012, 21,405,905 and 2,606,484 shares issued and outstanding at September 30, 2013 and December 31, 2012	214,000	26,000
Additional paid in capital	309,916,000	10,021,000
Accumulated other comprehensive loss	(18,000)
Accumulated deficit	(216,281,000)	(168,353,000)
Total stockholders' equity (deficit)	93,831,000	(158,306,000)
Total liabilities, redeemable convertible preferred stock and stockholders' equity (deficit)	$ 122,717,000	$ 83,852,000

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Condensed Consolidated Balance Sheets
Redeemable convertible preferred stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Redeemable convertible preferred stock, shares authorized	0	18,548,253
Redeemable convertible preferred stock, shares issued	0	16,912,199
Redeemable convertible preferred stock, shares outstanding	0	16,912,199
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	75,000,000	30,145,155
Common stock, shares issued	21,405,905	2,606,484
Common stock, shares outstanding	21,405,905	2,606,484

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
Condensed Consolidated Statements of Operations (USD $)	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Condensed Consolidated Statements of Operations
Revenue	$ 1,116,000	$ 42,803,000	$ 2,823,000	$ 43,221,000
Operating expenses:
General and administrative	5,927,000	8,922,000	12,390,000	13,009,000
Research and development	15,293,000	26,962,000	38,096,000	42,186,000
Total operating expenses	21,220,000	35,884,000	50,486,000	55,195,000
Income (loss) from operations	(20,104,000)	6,919,000	(47,663,000)	(11,974,000)
Change in fair value of warrant liability	(31,000)	(25,000)	(19,000)	365,000
Interest expense	(1,000)	(8,357,000)	(3,000)	(8,608,000)
Other income, net	47,000	28,000	189,000	567,000
Net loss before income taxes	(20,089,000)	(1,435,000)	(47,496,000)	(19,650,000)
Income taxes	432,000		432,000
Net loss	(20,521,000)	(1,435,000)	(47,928,000)	(19,650,000)
Accretion of redeemable convertible preferred stock	(269,000)	(785,000)	(2,320,000)	(2,943,000)
Net loss applicable to common stockholders	$ (20,790,000)	$ (2,220,000)	$ (50,248,000)	$ (22,593,000)
Net loss per share of common stock, basic and diluted (in dollars per share)	$ (1.34)	$ (1.02)	$ (7.23)	$ (10.36)
Basic and diluted weighted average shares outstanding (in shares)	15,480,416	2,174,392	6,946,248	2,181,795

Condensed Consolidated Statements of Comprehensive Loss (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Condensed Consolidated Statements of Comprehensive Loss
Net loss	$ (20,521,000)	$ (1,435,000)	$ (47,928,000)	$ (19,650,000)
Other comprehensive loss:
Foreign currency translation adjustments, net	(23,000)		(18,000)
Other comprehensive loss, net of tax	(23,000)		(18,000)
Comprehensive loss	$ (20,544,000)	$ (1,435,000)	$ (47,946,000)	$ (19,650,000)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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+ Details

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Deficit (USD $)	Total	Redeemable Convertible Preferred Stock	Common Stock	Additional Paid in Capital	Accumulated deficit	Accumulated other comprehensive loss
Balance at Dec. 31, 2011	$ (138,419,000)	$ 119,997,000	$ 22,000		$ (138,441,000)
Balance (in shares) at Dec. 31, 2011		11,227,169	2,167,928
Increase (Decrease) in Stockholders' Equity
Net loss	(19,650,000)				(19,650,000)
Issuance of preferred stock, net of issuance costs		47,796,000
Issuance of preferred stock, net of issuance costs (in shares)		3,030,303
Exercise of stock options	25,000			25,000
Exercise of stock options (in shares)			20,077
Settlement of stock option liabilities	182,000			182,000
Issuance of preferred stock upon exercise of warrants		2,802,000
Issuance of preferred stock upon exercise of warrants (in shares)		221,399
Exchange of convertible debt and preferred stock		26,767,000
Exchange of convertible debt and preferred stock (in shares)		2,433,328
Beneficial conversion feature on convertible debt	8,176,000			8,176,000
Accretion of preferred stock to redemption value	(2,943,000)	2,943,000		(2,943,000)
Balance at Sep. 30, 2012	(152,629,000)	200,305,000	22,000	5,440,000	(158,091,000)
Balance (in shares) at Sep. 30, 2012		16,912,199	2,188,005
Balance at Dec. 31, 2012	(158,306,000)	201,315,000	26,000	10,021,000	(168,353,000)
Balance (in shares) at Dec. 31, 2012		16,912,199	2,606,484
Increase (Decrease) in Stockholders' Equity
Net loss	(47,928,000)				(47,928,000)
Other comprehensive loss	(18,000)					(18,000)
Exercise of stock options	89,000			89,000
Exercise of stock options (in shares)			19,627
Stock-based compensation	4,386,000			4,386,000
Accretion of preferred stock to redemption value	(2,320,000)	2,320,000		(2,320,000)
Reclassification of stock option liability	14,482,000			14,482,000
Conversion of convertible preferred stock into common stock	203,635,000	(203,635,000)	129,000	203,506,000
Conversion of convertible preferred stock into common stock (in shares)		(16,912,199)	12,838,127
Issuance of common stock, net of issuance costs	79,811,000		59,000	79,752,000
Issuance of common stock, net of issuance costs (in shares)			5,941,667
Balance at Sep. 30, 2013	$ 93,831,000		$ 214,000	$ 309,916,000	$ (216,281,000)	$ (18,000)
Balance (in shares) at Sep. 30, 2013			21,405,905

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
Condensed Consolidated Statements of Cash Flows (USD $)	Sep. 30, 2013	Sep. 30, 2012
Operating activities:
Net loss	$ (47,928,000)	$ (19,650,000)
Adjustment to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	326,000	232,000
Amortization of deferred financing fees		15,000
Amortization of debt discount		8,176,000
Change in fair value of warrant liabilities	19,000	(365,000)
Stock compensation expense	6,939,000	13,231,000
Changes in assets and liabilities:
Grants receivable		78,000
Prepaid expenses and other current assets	(3,601,000)	(193,000)
Other assets		(15,000)
Accounts payable	(1,112,000)	13,153,000
Accrued expenses	3,892,000	3,599,000
Other liabilities	(14,000)	(31,000)
Deferred revenue	(2,775,000)	11,124,000
Net cash (used in) provided by operating activities	(44,254,000)	29,354,000
Investing activities:
Payments for purchase of property and equipment	(515,000)	(131,000)
Purchases of marketable securities	(39,990,000)
Net cash used in investing activities	(40,505,000)	(131,000)
Financing activities:
Proceeds from initial public offering of common stock, net of issuance costs	79,811,000
Proceeds from the exercise of stock options	51,000	25,000
Proceeds from the exercise of warrants		2,167,000
Proceeds from stockholder loan and convertible debt		25,824,000
Net cash provided by financing activities	79,862,000	76,212,000
Effect of foreign currency translation on cash	(18,000)
Net (decrease) increase in cash and cash equivalents	(4,915,000)	105,435,000
Cash and cash equivalents at beginning of period	81,527,000	2,713,000
Cash and cash equivalents at end of period	76,612,000	108,148,000
Series I Preferred Stock
Financing activities:
Proceeds from the sale of preferred stock		400,000
Series J Preferred Stock
Financing activities:
Proceeds from the sale of preferred stock		$ 47,796,000

Nature of Business	9 Months Ended
Nature of Business	Sep. 30, 2013
Nature of Business
Nature of Business	1. Nature of Business The Company Onconova Therapeutics, Inc. (the “Company”) was incorporated in the State of Delaware on December 22, 1998 and commenced operations on January 1, 1999. The Company’s headquarters are located in Newtown, Pennsylvania. The Company is a clinical-stage biopharmaceutical company focused on discovering and developing novel small molecule drug candidates to treat cancer. Using its proprietary chemistry platform, the Company has created an extensive library of targeted anti-cancer agents designed to work against specific cellular pathways that are important to cancer cells. The Company believes that the drug candidates in its pipeline have the potential to be efficacious in a wide variety of cancers without causing harm to normal cells. The Company has three clinical-stage product candidates and six preclinical programs. To accelerate and broaden the development of rigosertib, the Company’s most advanced product candidate, the Company entered into a collaboration and license agreement with Baxter Healthcare SA (“Baxter”), a subsidiary of Baxter International Inc., in 2012 to commercialize rigosertib in Europe. In 2011, the Company entered into a collaboration and license agreement with SymBio Pharmaceuticals Limited (“SymBio”) to commercialize rigosertib in Japan and Korea. The Company has retained development and commercialization rights to rigosertib in the rest of the world, including the United States. During 2012, Onconova Europe GmbH was established as a wholly owned subsidiary of the Company for the purpose of further developing business in Europe. In April 2013, GBO, LLC, a Delaware limited liability company, (“GBO”) was formed as a joint venture with GVK Biosciences Private Limited, a private limited company located in India, (“GVK BIO”) to collaborate and develop two new clinical programs using the Company’s technology platform. Liquidity The Company has incurred recurring operating losses since inception. For the nine months ended September 30, 2013, the Company incurred a net loss of $47,928,000 and as of September 30, 2013, the Company had generated an accumulated deficit of $216,281,000. The Company anticipates operating losses to continue for the foreseeable future due to, among other things, costs related to research funding, development of its product candidates and its preclinical programs, strategic alliances and the development of its administrative organization. The Company raised significant capital through the issuance of its redeemable convertible preferred stock, par value $0.01 per share, in ten series denominated as Series A through Series J (“Series A Preferred Stock” through “Series J Preferred Stock,” respectively, and collectively the “Preferred Stock”). See Note 7. On July 30, 2013, the Company completed its initial public offering (the “IPO”) of 5,941,667 shares of the Company’s common stock, par value $0.01 per share (“Common Stock”), at a price of $15.00 per share, including 775,000 shares of Common Stock issued upon the exercise in full by the underwriters of their option to purchase additional shares at the same price to cover over-allotments. The Company received net proceeds of $79,811,000 from the sale, net of underwriting discounts and commissions and other estimated offering expenses. Immediately prior to the consummation of the IPO, all outstanding shares of Preferred Stock automatically converted into shares of Common Stock at the applicable conversion ratio then in effect. As a result of the conversion, as of July 30, 2013, the Company had no shares of Preferred Stock outstanding. See Note 12. The accompanying condensed consolidated financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business. The Company’s ability to continue as a going concern is dependent on its ability to raise additional capital to fund its research and development and commercial programs and meet its obligations. Management intends to fund future operations through additional equity offerings, licensing revenue, grants, government contracts and, if any of the Company’s product candidates receive marketing approval, future sales of its products. There can be no assurance, however, that the Company will be successful in obtaining financing at the level needed to sustain operations or on terms acceptable to the Company, or that the Company will obtain approvals necessary to market its products or achieve profitability or sustainable, positive cash flow. The Company faces many risks associated with companies in the early stages. It also faces risks inherent in its business and its industry generally. These risks include, among others, the following: · the Company’s success is primarily dependent on the regulatory approval and commercialization of rigosertib; · the Company is subject to regulatory approval processes that are lengthy, time consuming, expensive and unpredictable. The Company may not obtain approval on a timely basis or at all for any of its product candidates from the U.S. Food and Drug Administration or foreign regulatory authorities; · the Company has no significant source of product revenue, may never become profitable and may incur substantial and increasing net losses for the foreseeable future as it continues to develop and seek regulatory approvals for, and potentially begins to commercialize, its product candidates; · the Company may need to obtain additional funding to continue operations; · it is difficult and costly to protect the Company’s intellectual property rights; · the Company may be unable to recruit or retain key employees, including its senior management team; and · the Company depends on the performance of third parties, including contract research organizations and third-party manufacturers.

Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 2013
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The condensed consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States (“GAAP”) for interim financial information. Certain information and footnotes normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). The financial statements include the consolidated accounts of the Company, its wholly-owned subsidiary, Onconova Europe GmbH and its joint venture, GBO, LLC. All significant intercompany transactions have been eliminated. Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of September 30, 2013, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2013 and 2012, the condensed consolidated statements of redeemable convertible preferred stock and stockholders’ deficit and the condensed consolidated statements of cash flows for the nine months ended September 30, 2013 and 2012 are unaudited. The interim unaudited condensed consolidated financial statements have been prepared on the same basis as the annual audited consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of September 30, 2013 and the results of its operations, its comprehensive loss and its cash flows for the nine months ended September 30, 2013 and 2012. The financial data and other information disclosed in these notes related to the nine months ended September 30, 2013 and 2012 are unaudited. The results for the nine months ended September 30, 2013 are not necessarily indicative of results to be expected for the year ending December 31, 2013, any other interim periods, or any future year or period. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto for the year ended December 31, 2012 included in the Company’s final prospectus filed on July 25, 2013 with the SEC pursuant to Rule 424(b)(4) of the Securities Act of 1933, as amended (the “Securities Act”). Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one segment, which is the identification and development of oncology therapeutics. Significant Accounting Policies The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2012 included in the Company’s final prospectus filed on July 25, 2013 with the SEC pursuant to Rule 424(b)(4) of the Securities Act. Since the date of such financial statements, there have been no changes to the Company’s significant accounting policies. Foreign Currency Translation The reporting currency of the Company and its U.S. subsidiary is the U.S. dollar. The functional currency of the Company’s non-U.S. subsidiary is the local currency. Assets and liabilities of the foreign subsidiary are translated into U.S. dollars based on exchange rates at the end of the period. Revenues and expenses are translated at average exchange rates during the reporting period. Gains and losses arising from the translation of assets and liabilities are included as a component of accumulated other comprehensive income. Gains and losses resulting from foreign currency transactions are reflected within the Company’s results of operations. The Company has not utilized any foreign currency hedging strategies to mitigate the effect of its foreign currency exposure. Marketable Securities Marketable securities with original maturities longer than three months but which mature in less than one year from the balance sheet date are classified as current assets. Marketable securities that mature more than one year from the balance sheet date are classified as noncurrent assets. Marketable securities that the Company has the intent and ability to hold to maturity are classified as investments held-to-maturity and are reported at amortized cost. The difference between the acquisition cost and face values of held-to-maturity investments is amortized over the remaining term of the investments and added to or subtracted from the acquisition cost and interest income. As of September 30, 2013, all of the Company’s investments were classified as held-to-maturity. Recent Accounting Pronouncements In February 2013, the Financial Accounting Standards Board (the “FASB”) amended its guidance to require an entity to present the effect of certain significant reclassifications out of accumulated other comprehensive income on the respective line items in net income. The new accounting guidance does not change the items that must be reported in other comprehensive income or when an item of other comprehensive income must be reclassified to net income. The guidance is effective prospectively for fiscal years beginning after December 15, 2012. The Company adopted these new provisions for the quarter beginning January 1, 2013. As the guidance requires additional presentation only, there was no impact to the Company’s consolidated financial position, results of operations or cash flows. In July 2013, the FASB issued guidance clarifying that an unrecognized tax benefit, or a portion of an unrecognized tax benefit, should be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward if such settlement is required or expected in the event the uncertain tax benefit is disallowed. In situations where a net operating loss carryforward, a similar tax loss, or a tax credit carryforward is not available at the reporting date under the tax law of the applicable jurisdiction or the tax law of the jurisdiction does not require, and the entity does not intend to use, the deferred tax asset for such purpose, the unrecognized tax benefit should be presented in the financial statements as a liability and should not be netted with the deferred tax asset. The guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2013. Early adoption is permitted. The guidance is to be applied prospectively to all unrecognized tax benefits that exist at the effective date. Retrospective application is permitted. The Company is currently evaluating the impact that adoption will have on the determination or reporting of its financial results.

- Definition

The entire disclosure for the organization, consolidation and basis of presentation of financial statements disclosure, and significant accounting policies of the reporting entity. May be provided in more than one note to the financial statements, as long as users are provided with an understanding of (1) the significant judgments and assumptions made by an enterprise in determining whether it must consolidate a VIE and/or disclose information about its involvement with a VIE, (2) the nature of restrictions on a consolidated VIE's assets reported by an enterprise in its statement of financial position, including the carrying amounts of such assets, (3) the nature of, and changes in, the risks associated with an enterprise's involvement with the VIE, and (4) how an enterprise's involvement with the VIE affects the enterprise's financial position, financial performance, and cash flows. Describes procedure if disclosures are provided in more than one note to the financial statements.

+ References+ Details

Fair Value Measurements

9 Months Ended

Sep. 30, 2013

Fair Value Measurements

Fair Value Measurements

3. Fair Value Measurements

The Company applies various valuation approaches in determining the fair value of its financial assets and liabilities within a hierarchy that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available under the circumstances. The fair value hierarchy is broken down into three levels based on the source of inputs as follows:

Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access.

Level 2—Valuations based on quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active and models for which all significant inputs are observable, either directly or indirectly.

Level 3—Valuations based on inputs that are unobservable and significant to the overall fair value measurement.

The availability of observable inputs can vary among the various types of financial assets and liabilities. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, for financial statement disclosure purposes, the level in the fair value hierarchy within which the fair value measurement is classified is based on the lowest level input that is significant to the overall fair value measurement.

The Company had no assets or liabilities classified as Level 1 or Level 2. The warrants (see Note 7) are classified as Level 3. The fair values of these instruments are determined using models based on market observable inputs and management judgment. There were no material re-measurements of fair value during the nine months ended September 30, 2013 and the year ended December 31, 2012 with respect to financial assets and liabilities, other than those assets and liabilities that are measured at fair value on a recurring basis.

The Company has classified the warrants as a liability and has re-measured the liability to estimated fair value at September 30, 2013 and December 31, 2012, using the Black-Scholes option pricing model with the following assumptions: contractual life according to the remaining terms of the warrants, no dividend yield, weighted average risk-free interest rates of 0.40% and 0.31% at September 30, 2013 and December 31, 2012, respectively, and weighted average volatility of 73.93% and 64.87% at September 30, 2013 and December 31, 2012, respectively. The volatility was based on average historical share price trading data for a group of 11 comparable companies.

The following fair value hierarchy table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis as of September 30, 2013 and December 31, 2012:

	Fair Value Measurement as of September 30, 2013								Fair Value Measurement as of December 31, 2012
	Level 1		Level 2		Level 3		Balance		Level 1		Level 2		Level 3		Balance

Warrant liability	$	—	$	—	$	81,000	$	81,000	$	—	$	—	$	62,000	$	62,000
Total	$	—	$	—	$	81,000	$	81,000	$	—	$	—	$	62,000	$	62,000

The following table presents a reconciliation of the Company’s liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the nine months ended September 30, 2013:

	Warrant Liability
Balance at December 31, 2012	$	62,000
Change in fair value upon re-measurement	19,000
Balance at September 30, 2013	$	81,000

There were no transfers between Level 1 and Level 2 in any of the periods reported.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References+ Details

Marketable Securities

9 Months Ended

Sep. 30, 2013

Marketable Securities

Marketable Securities

4. Marketable Securities

Marketable securities with initial maturities longer than three months but that mature within one year from the balance sheet date are classified as current assets and are summarized as follows:

	September 30, 2013		December 31, 2012

U.S. Treasury obligations	$	39,990,000	$	—

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 9

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-Glossary Debt Security

-URI http://asc.fasb.org/extlink&oid=6509901

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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-Paragraph 5

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 320

-Section 50

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Reference 8: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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-Paragraph 10

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-Glossary Equity Security

-URI http://asc.fasb.org/extlink&oid=6511694

+ Details

Net Loss Per Share of Common Stock

9 Months Ended

Sep. 30, 2013

Net Loss Per Share of Common Stock

Net Loss Per Share of Common Stock

5. Net Loss Per Share of Common Stock

The following potentially dilutive securities outstanding at September 30, 2013 and 2012 have been excluded from the computation of diluted weighted average shares outstanding, as they would be antidilutive:

	September 30,
	2013	2012
Preferred Stock	—	12,838,317
Warrants	4,597	4,597
Stock options	3,549,842	2,112,644
	3,554,439	14,955,558

- Definition

The entire disclosure for earnings per share.

+ References+ Details

Balance Sheet Detail

9 Months Ended

Sep. 30, 2013

Balance Sheet Detail

Balance Sheet Detail

6. Balance Sheet Detail

Prepaid expenses and other current assets:

	September 30,		December 31,
	2013		2012

Research and development	$	2,476,000	$	1,429,000
Manufacturing	1,566,000		—
Insurance	889,000		101,000
Other	395,000		195,000
	$	5,326,000	$	1,725,000

Property and equipment:

	September 30,			December 31,
	2013			2012

Property and equipment	$	2,326,000		$	1,811,000
Accumulated depreciation	(1,674,000		)	(1,348,000		)
	$	652,000		$	463,000

Accrued expenses and other current liabilities:

	September 30,		December 31,
	2013		2012

Research and development	$	4,944,000	$	3,521,000
Employee compensation	2,087,000		247,000
Income taxes	432,000		—
Other	354,000		157,000
	$	7,817,000	$	3,925,000

Preferred Stock and Stockholders' Deficit

9 Months Ended

Sep. 30, 2013

Preferred Stock and Stockholders' Deficit

Preferred Stock and Stockholders' Deficit

7. Preferred Stock and Stockholders’ Deficit

Capitalization

The following is the composition of share capital as of the dates indicated:

	Authorized		Issued and Outstanding
	September 30,	December 31,	September 30,	December 31,
	2013	2012	2013	2012
Shares of $0.01 par value per share:
Common stock	75,000,000	30,145,155	21,405,905	2,606,484

Series A Preferred Stock	—	400,000	—	107,000
Series B Preferred Stock	—	1,200,000	—	1,107,189
Series C Preferred Stock	—	1,200,000	—	1,069,946
Series D Preferred Stock	—	1,625,000	—	1,583,568
Series E Preferred Stock	—	1,650,000	—	1,633,082
Series F Preferred Stock	—	2,000,000	—	2,000,000
Series G Preferred Stock	—	2,700,000	—	1,934,359
Series H Preferred Stock	—	2,042,950	—	2,013,424
Series I Preferred Stock	—	2,700,000	—	2,433,328
Series J Preferred Stock	—	3,030,303	—	3,030,303
Total Preferred Stock	—	18,548,253	—	16,912,199

In preparation for the IPO, the Company’s board of directors and stockholders approved a one-for-1.333 reverse stock split of the Company’s Common Stock. The reverse stock split became effective on July 17, 2013. All Common Stock share and per share amounts in the condensed consolidated financial statements and notes thereto have been retroactively adjusted for all periods presented to give effect to this reverse stock split, including reclassifying an amount equal to the reduction in par value of common stock to additional paid-in capital. The reverse stock split did not result in a retroactive adjustment of share amounts for the Preferred Stock.

In July 2012, the Company issued 2,433,328 shares of Series I Preferred Stock in exchange for the conversion of the convertible promissory notes and accrued interest in the amount of $26,444,000 and $323,000, respectively. The effective conversion price was $11.00 per share. Additionally, in July 2012, the Company issued 3,030,303 shares of Series J Preferred Stock at $16.50 per share for gross proceeds of $50,000,000. Issuance costs associated with this offering were $2,204,000.

Series A Preferred Stock was issued at $5.00 per share; Series B Preferred Stock was issued at $5.75 per share; Series C Preferred Stock was issued at $3.56 per share; Series D Preferred Stock was issued at $4.67 per share; Series E Preferred Stock was issued at $9.76 per share; Series F Preferred Stock was issued at $11.00 per share; Series G and Series H Preferred Stock were issued at $9.79 per share; Series I Preferred Stock was issued at $11.00 per share; and Series J Preferred Stock was issued at $16.50 per share.

The following is the activity of the Preferred Stock for the nine months ended September 30, 2013:

	December 31, 2012		Issuance of Preferred Stock		Exercise of warrants		Accretion of redemption premium and issuance costs on Preferred Stock		Conversion of Preferred Stock into Common Stock			September 30, 2013
Series A
Shares	107,000		—		—		—		(107,000		)	—
Amount	$	535,000	$	—	$	—	$	—	$	(535,000	)	$	—
Series B
Shares	1,107,189		—		—		—		(1,107,189		)	—
Amount	$	12,733,000	$	—	$	—	$	—	$	(12,733,000	)	$	—
Series C
Shares	1,069,946		—		—		—		(1,069,946		)	—
Amount	$	7,618,000	$	—	$	—	$	—	$	(7,618,000	)	$	—
Series D
Shares	1,583,568		—		—		—		(1,583,568		)	—
Amount	$	18,211,000	$	—	$	—	$	—	$	(18,211,000	)	$	—
Series E
Shares	1,633,082		—		—		—		(1,633,082		)	—
Amount	$	18,780,000	$	—	$	—	$	—	$	(18,780,000	)	$	—
Series F
Shares	2,000,000		—		—		—		(2,000,000		)	—
Amount	$	23,000,000	$	—	$	—	$	—	$	(23,000,000	)	$	—
Series G
Shares	1,934,359		—		—		—		(1,934,359		)	—
Amount	$	22,819,000	$	—	$	—	$	—	$	(22,819,000	)	$	—
Series H
Shares	2,013,424		—		—		—		(2,013,424		)	—
Amount	$	22,005,000	$	—	$	—	$	868,000	$	(22,873,000	)	$	—
Series I
Shares	2,433,328		—		—		—		(2,433,328		)	—
Amount	$	26,933,000	$	—	$	—	$	226,000	$	(27,159,000	)	$	—
Series J
Shares	3,030,303		—		—		—		(3,030,303		)	—
Amount	$	48,681,000	$	—	$	—	$	1,226,000	$	(49,907,000	)	$	—
Total
Shares	16,912,199		—		—		—		(16,912,199		)	—
Amount	$	201,315,000	$	—	$	—	$	2,320,000	$	(203,635,000	)	$	—

Voting

Prior to the consummation of the IPO, each holder of outstanding shares of Preferred Stock had the right to one vote for each share of Common Stock into which such Preferred Stock could then be converted. The holders of shares of Preferred Stock had full voting rights and powers equal to the voting rights and powers of shares of Common Stock and were entitled to notice of any stockholders’ meeting and voted together with the holders of Common Stock, with respect to any question upon which holders of shares of Common Stock have the right to vote, as a single class, including without limitation, actions to increase or decrease the aggregate number of authorized shares of Common Stock and/or Preferred Stock.

Dividends

Prior to the consummation of the IPO, the holders of each share of Series A, Series B, Series C, Series D, Series E, Series F, Series G, Series H, Series I and Series J Preferred Stock were entitled to receive dividends when, as, and if declared by the Company’s board of directors in the following order of preference: (i) the Series D, Series E, Series F, Series G, Series H, Series I and Series J Preferred Stock, which ranked pari passu; (ii) the Series B and Series C Preferred Stock, which ranked pari passu; (iii) the Series A Preferred Stock; and then (iv) Common Stock.

Liquidation

Prior to the consummation of the IPO, the assets of the Company legally available for distribution to stockholders were distributable in the following order of priority: (i) the holders of the shares of Series D, Series E, Series F, Series G, Series H, Series I and Series J Preferred Stock, which ranked pari passu; (ii) the holders of the shares of Series B and Series C Preferred Stock, which ranked pari passu; (iii) the holders of the shares of Series A Preferred Stock; and (iv) the holders of the shares of Common Stock. Each series of Preferred Stock was entitled to receive an amount per share equal to the greater of (1) the original issuance price for such series, plus all declared but unpaid dividends thereon, or (2) the amount that the holders of such series would receive per share of Common Stock if all shares of such series of Preferred Stock were converted to Common Stock immediately prior to such liquidation. If, upon a deemed liquidation event, the assets of the Company were insufficient to make payment in full to all holders of a series of Preferred Stock, then such assets would be distributed among the holders of such series of Preferred Stock at the time outstanding ratably in proportion to the full amount to which they would otherwise be respectively entitled. The holders of Common Stock were entitled to receive, after the payment of the liquidation preference of all Preferred Stock outstanding, the remaining assets of the Company on a pro rata basis.

Conversion

Prior to the consummation of the IPO, each issued and outstanding share of Preferred Stock was convertible into Common Stock at the holder’s option at any time after the date of issuance or automatically upon the occurrence of certain events as defined in the Company’s ninth amended and restated certificate of incorporation, at a defined conversion rate. Prior to the consummation of the IPO, the number of shares of Common Stock into which one share of each series of Preferred Stock was convertible was as follows, after giving effect to the reverse stock split discussed in Note 12: the Series A Preferred Stock, 0.80; the Series B Preferred Stock, 0.85; the Series C Preferred Stock, 0.75; the Series D Preferred Stock, 0.75; the Series E Preferred Stock, 0.75; the Series F Preferred Stock, 0.77; the Series G Preferred Stock, 0.75; the Series H Preferred Stock, 0.75; the Series I Preferred Stock, 0.75; and the Series J Preferred Stock, 0.75.

The conversion price for each share of Preferred Stock was subject to adjustment upon the occurrence of certain events. The conversion price of each share of a series of Preferred Stock was adjusted if the Company issued additional shares, subject to specified exceptions, at a price lower than the then current conversion price for such series, which is measured and recognized if the contingency occurs.

On July 30, 2013, immediately prior to the consummation of the IPO, all outstanding shares of Preferred Stock automatically converted into shares of Common Stock at the applicable conversion ratio then in effect. See Note 12.

Redemption

To the extent it was then lawfully able to do so, the Company was required at any time, upon written request of the holders of at least 66.67% of the then outstanding Series A, Series B and Series C Preferred Stock collectively, or upon written request of the holders of at least a majority of the then outstanding shares of Series D, Series E and Series F Preferred Stock collectively, in each case as determined on an as-converted to Common Stock basis, to redeem the requested number of outstanding shares of Series A Preferred Stock at $5.00 per share, Series B Preferred Stock at $11.50 per share, and Series C Preferred Stock at $7.12 per share, and/or Series D, E and F Preferred Stock at $11.50 per share, as the case may be.

In addition, to the extent it was lawfully able to do so, the Company was required at any time, upon written request of the holders of at least a majority of the then outstanding shares of Series G Preferred Stock, to redeem, from the holders requesting such redemption, the requested number of outstanding shares of Series G Preferred Stock at $11.50 per share.

To the extent it would have been lawfully able to do so, the Company would have been required at any time on or after September 21, 2013, upon written request of the holders of at least a majority of the then outstanding shares of Series H Preferred Stock, to redeem, from the holders requesting such redemption, the requested number of outstanding shares of Series H Preferred Stock at $11.50 per share.

To the extent it would have been lawfully able to do so, the Company would have been required at any time on or after July 25, 2015, upon written request of the holders of at least a majority of the then outstanding shares of Series I Preferred Stock, to redeem, from the holders requesting such redemption, the requested number of outstanding shares of Series I Preferred Stock at $11.50 per share.

To the extent it would have been lawfully able to do so, the Company would have been required at any time on or after July 27, 2015, upon written request of the holders of at least a majority of the then outstanding shares of Series J Preferred Stock, to redeem, from the holders requesting such redemption, the requested number of outstanding shares of Series J Preferred Stock at $18.00 per share.

If, upon any applicable redemption date, defined as 60 days after the Company receives the written request for redemption, the funds of the Company legally available for redemption of Preferred Stock would have been insufficient to redeem the total number of shares to be redeemed on that date, those funds that were legally available would have been used to redeem the maximum possible number of shares, ratably among the holders of such shares to be redeemed. All remaining shares not redeemed would have remained outstanding until such time as additional funds became legally available for redemption.

If more than one series of Preferred Stock had been contemporaneously subject to redemption, the redemption rights of the Preferred Stock would have followed the liquidation order of priority.

Warrant Transactions

The Company issued 6,128 Series G Preferred Stock warrants in connection with a Loan and Security Agreement. Additionally, the Company issued one Series G Preferred Stock warrant for every two shares of Series G Preferred Stock purchased in 2009 and 2010. The warrants were initially recorded at their fair value calculated using the Black-Scholes model, with the following weighted average assumptions: exercise price of $9.79, share price of $9.79, expected term of three years, risk-free rate of 1.52% and volatility of 85.46%. The warrants are classified as liabilities due to certain anti-dilution provisions, and the value of the warrants is adjusted to current fair value at each reporting period end. For the three and nine months ended September 30, 2013, the Company recorded $(31,000) and $(19,000), respectively, in the consolidated statements of operations and comprehensive loss related to the change in the fair value of the outstanding warrants.

Immediately prior to the consummation of the IPO, the 6,128 Series G Preferred Stock warrants outstanding were automatically converted into 4,597 Common Stock warrants (after giving effect to the one-for-1.333 reverse stock split).

Stock-Based Compensation

9 Months Ended

Sep. 30, 2013

Stock-Based Compensation

Stock-Based Compensation

8. Stock-Based Compensation

In January 2008, the board of directors approved the 2007 Equity Compensation Plan (the “2007 Plan”), which amended, restated and renamed the Company’s 1999 Stock Based Compensation Plan (the “1999 Plan”), which provided for the granting of incentive and nonqualified stock options and restricted stock to its employees, directors and consultants at the discretion of the board of directors. Under the 2007 Plan, the Company increased the number of shares reserved for issuance under the 2007 Plan such that the number of reserved shares is equal to 17% of the fully diluted shares calculated annually on December 10th.

Further, in July 2013, the Company’s board of directors and stockholders approved, effective immediately prior to the listing of the Common Stock on the NASDAQ Global Market, the 2013 Equity Compensation Plan (the ‘‘2013 Plan’’), which amended, restated and renamed the 2007 Plan . Under the 2013 Plan, the Company may grant incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock, restricted stock units, deferred share awards, performance awards and other equity-based awards to employees, directors and consultants. The Company initially reserved 6,107,831 shares of Common Stock for issuance, subject to adjustment as set forth in the 2013 Plan, of which 1,532,336 shares of Common Stock will be available for future issuance. On July 25, 2013, in conjunction with the IPO, the Company issued 485,500 stock options.

	September 30,		December 31,
	2013	2012	2012	2011
Shares of Common Stock reserved for issuance under the 2013 Plan	6,107,831	4,107,831	4,107,831	3,046,975

Stock options may be granted with exercise prices of not less than the estimated fair value of the Common Stock on the date of grant and generally vest over a period of up to four years. Stock options granted under the 2013 Plan generally expire no later than ten years from the date of grant. A summary of stock option activity for the nine months ended September 30, 2013 is as follows:

					Weighted-
					Average
			Weighted-		Remaining
			Average		Contractual
	Number of		Exercise		Term
	Options		Price		(in years)
Outstanding at December 31, 2012	2,564,147		$	8.10	7.52
Granted	1,095,840		14.62
Exercised	(19,627	)	2.62
Forfeited	(90,518	)	12.89
Outstanding at September 30, 2013	3,549,842		$	10.01	7.79

Vested or expected to vest at September 30, 2013	3,549,842		$	10.01	7.79
Exercisable at September 30, 2013	2,175,739		$	7.97	6.84

At September 30, 2013 and December 31, 2012, the aggregate intrinsic value of the option liability recorded was $0 and $11,967,000, respectively. During the nine months ended September 30, 2013, the Company granted 1,095,840 options at an intrinsic value of $0 at the grant date. At certain times throughout the Company’s history, the chairman of the Company’s board of directors, who is also a significant stockholder of the Company (the “Significant Holder”), has afforded option holders the opportunity for liquidity in transactions in which options were exercised and the shares of Common Stock issued in connection therewith were simultaneously purchased by the Significant Holder (each, a “Purchase Transaction”). Because the Company has established a pattern of providing cash settlement alternatives for option holders, the Company has accounted for its stock-based compensation awards as liability awards, the fair value of which is then re-measured at each balance sheet date. Upon the exercise of stock options from January 1, 2013 through April 23, 2013, stock option liabilities of $38,000 were reclassified to stockholders’ deficit.

On April 23, 2013, the Company distributed a notification letter to all equity award holders under the 2007 Plan advising them that Purchase Transactions would no longer occur, unless, at the time of a Purchase Transaction, the option holder has held the Common Stock issued upon exercise of options for a period of greater than six months prior to selling such Common Stock to the Significant Holder and that any such sale to the Significant Holder would be at the fair value of the Common Stock on the date of such sale. Based on these new criteria for Purchase Transactions, the Company remeasured options outstanding under the 2007 Plan as of April 23, 2013 to their intrinsic value and reclassified such options from liabilities to stockholders’ deficit within the Company’s consolidated balance sheets, which amounted to $14,482,000.

A roll forward of the stock option liability balance for the nine months ended September 30, 2013 is as follows:

Balance at December 31, 2012	$	11,967,000
Change in fair value upon remeasurement	2,553,000
Settlements of option liability awards	(38,000		)
Stock option award modification	(14,482,000		)
Balance at September 30, 2013	$	—

The Company accounts for all stock-based payments made after April 23, 2013 to employees and directors using an option pricing model for estimating fair value. Accordingly, stock-based compensation expense is measured based on the estimated fair value of the awards on the date of grant, net of forfeitures. Compensation expense is recognized for the portion that is ultimately expected to vest over the period during which the recipient renders the required services to the Company using the straight-line single option method. In accordance with authoritative guidance, the fair value of non-employee stock based awards is re-measured as the awards vest, and the resulting increase in fair value, if any, is recognized as expense in the period the related services are rendered.

The Company estimates the fair value of its share-based awards to employees and directors using the Black-Scholes option pricing model. The Black-Scholes model requires the input of highly complex and subjective assumptions, including (a) the expected stock price volatility, (b) the calculation of the expected term of the award, (c) the risk free interest rate and (d) expected dividends. Due to the Company’s limited operating history and a lack of company specific historical and implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. When selecting these public companies on which it has based its expected stock price volatility, the Company selected companies with comparable characteristics to it, including enterprise value, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected life of the stock-based awards. The historical volatility data was computed using the daily closing prices for the selected companies’ shares during the equivalent period of the calculated expected term of the stock-based awards. Due to its lack of sufficient historical data, the Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. The Company has estimated the expected life of its employee stock options using the “simplified” method, whereby, the expected life equals the arithmetic average of the vesting term and the original contractual term of the option. The risk-free interest rates for periods within the expected life of the option are based on the U.S. Treasury yield curve in effect during the period the options were granted. The Company has never paid, and does not expect to pay dividends in the foreseeable future.

Stock-based compensation expense includes stock options granted to employees and non-employees and has been reported in the Company’s statements of operations and comprehensive loss in either research and development expenses or general and administrative expenses depending on the function performed by the optionee. No net tax benefits related to the stock-based compensation costs have been recognized since the Company’s inception.

During the period from April 23, 2013 through September 30, 2013, the Company granted options to purchase shares of its Common Stock as follows:

Shares	Exercise Price
3,900	$	14.74
752,000	$	15.00
17,500	$	21.79

The Company recorded $3,751,000 of compensation expense related to these options. The fair value of these options was estimated using the Black-Scholes option pricing model with the following weighted-average assumptions: no dividend yield, volatility of 78.40%, maximum contractual life of 5.59 years, and a risk-free interest rate of 1.51%.

The Company recognized stock-based compensation expense as follows for the three and nine months ended September 30, 2013 and 2012:

	Quarter Ended September 30,				Nine Months Ended September 30,
	2013		2012		2013		2012

General and administrative	$	2,821,000	$	5,559,000	$	4,347,000	$	6,880,000
Research and development	1,275,000		5,131,000		2,592,000		6,351,000
	$	4,096,000	$	10,690,000	$	6,939,000	$	13,231,000

As of September 30, 2013, there was $2,224,000 of unrecognized compensation expense related to the unvested liability awards, which is expected to be recognized over a weighted-average period of approximately 2.35 years.

As of September 30, 2013, there was $3,948,000 of unrecognized compensation expense related to the unvested stock options issued from April 23, 2013 through September 30, 2013, which is expected to be recognized over a weighted-average period of approximately 3.33 years. The Company accounts for stock options issued to nonemployees using a fair value approach.

Information with respect to stock options outstanding and exercisable at September 30, 2013 is as follows:

			Weighted
			Average
			Remaining
Exercise			Contractual
Price		Shares	Life (years)	Exercisable
$	1.33	149,987	0.84	149,987
2.67		65,207	2.32	65,207
5.76		396,941	6.44	378,063
6.00		415,267	3.93	415,267
6.13		592,906	6.66	506,444
7.53		49,982	6.31	35,410
13.28		1,105,252	9.33	252,497
14.74		4,800	9.66	4,800
15.00		752,000	9.82	368,064
21.79		17,500	9.82	—
		3,549,842	6.84	2,175,739

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References+ Details

License and Collaboration Agreements	9 Months Ended
License and Collaboration Agreements	Sep. 30, 2013
License and Collaboration Agreements
License and Collaboration Agreements	9. License and Collaboration Agreements Baxter Agreement In September 2012, the Company entered into a development and license agreement with Baxter granting Baxter an exclusive, royalty-bearing license for the research, development, commercialization and manufacture (in specified instances) of rigosertib in all therapeutic indications in Europe (the “Baxter Territory”). Baxter is a stockholder in the Company and invested in Series J Preferred Stock issued in July 2012. Under the terms of the agreement, the Company is initially required to perform research and development to advance three initial rigosertib indications, rigosertib intravenous (“rigosertib IV”) in higher risk myelodysplastic syndrome (“MDS”) patients, rigosertib IV in pancreatic cancer patients and rigosertib oral (“rigosertib Oral”) in lower risk MDS patients, through phase 3, phase 3 and phase 2 clinical trials, respectively. If an additional phase 3 clinical trial beyond the current phase 3 clinical trial in process for rigosertib IV in higher risk MDS patients is required to obtain marketing approval in the Baxter Territory, the Company could require Baxter to fund a percentage of the costs of such additional trial up to a specified maximum. At the completion of the current phase 3 trial for rigosertib IV in pancreatic cancer and the current phase 2 trial for rigosertib Oral in lower risk MDS patients and the review of the resulting data and findings, the Company and Baxter will decide whether or not to pursue further development of rigosertib for these indications. If the Company and Baxter mutually agree to progress the development of rigosertib IV in pancreatic cancer patients and rigosertib Oral in lower risk MDS patients, then certain milestone payments will be payable to the Company, and the Company will be required to use its commercially reasonable efforts to progress the development of rigosertib for these indications to a drug approval application in the Baxter Territory. The Company and Baxter will work together for potential future rigosertib indications, beyond the initial indications noted above. Generally, if Baxter chooses to participate in the development of additional indications, Baxter will be responsible for a percentage of all research and development costs and expenses and the Company could earn additional milestone payments. Baxter has full responsibility for all commercialization activities for the product in the Baxter Territory, at Baxter’s sole cost and expense. The Company and Baxter have agreed to negotiate a supply agreement under terms satisfactory to both parties whereby the Company will supply Baxter with Baxter’s required levels of product to support commercialization efforts in the Baxter Territory. Baxter also has the right to engage third parties for the manufacture and supply of its requirements for the licensed product. Under the terms of the agreement, Baxter made an upfront payment of $50,000,000. The Company is eligible to receive pre-commercial milestone payments of up to an aggregate of $512,500,000 if specified development and regulatory milestones are achieved. The potential pre-commercial development milestone payments to the Company include the following: · $50,000,000 for successful completion of a phase 3 clinical trial for rigosertib IV in higher risk MDS patients; · $25,000,000 for each of the two joint decisions to proceed with the development of rigosertib for certain indications specified in the arrangement with Baxter; and · $25,000,000 for each drug approval application filed for indications specified in the arrangement with Baxter. The Company may also receive up to $337,500,000 in milestone payments for regulatory approvals of the three rigosertib indications specified in the arrangement with Baxter, each of which may be up to and in excess of $100,000,000. The Company is also potentially eligible to receive an additional $20,000,000 pre-commercial milestone payment related to the timing of regulatory approval for rigosertib IV in higher risk MDS patients in Europe. In addition to these pre-commercial milestones, the Company is eligible to receive up to an aggregate of $250,000,000 in milestone payments based on Baxter’s achievement of pre-specified threshold levels of annual net sales of rigosertib. The Company will also be entitled to receive royalties at percentage rates ranging from the low-teens to the low-twenties on net sales of rigosertib by Baxter in the Baxter Territory. The agreement with Baxter will remain in effect until the expiration of all applicable royalty terms and satisfaction of all payment obligations in each licensed country, unless terminated earlier due to the uncured material breach or bankruptcy of a party, force majeure, or in the event of a specified commercial failure. The Company may terminate the agreement in the event that Baxter brings a challenge against it in relation to the licensed patents. Baxter may terminate the agreement without cause commencing after a specified period of time from the execution of the agreement. The Company has determined that the deliverables under the Baxter agreement include the exclusive, royalty-bearing, sublicensable license to rigosertib and the research and development services to be performed by the Company. The Company concluded that the license had standalone value to Baxter and was separable from the research and development services because the license is sublicensable, there are no restrictions as to Baxter’s use of the license and Baxter has significant research capabilities in this field. In determining the separate units of accounting, the Company considered applicable accounting guidance and noted that in an arrangement with multiple deliverables, the delivered item or items shall be considered a separate unit of accounting if the delivered item or items have value to the customer on a stand-alone basis. The item or items have value on a stand-alone basis if they are sold separately by any vendor or the customer could resell the delivered item(s) on a stand-alone basis. In the context of a customer’s ability to resell the delivered item(s), this criterion does not require the existence of an observable market for the deliverable(s). The Baxter agreement allows Baxter to sublicense rigosertib and its ability to sublicense is not contingent on the approval or right of first refusal by the Company. The Company determined that Baxter’s ability to sublicense the intellectual property to others demonstrates that the license has stand-alone value. In addition, at the time of entering into the Baxter agreement in September 2012, the rigosertib program was in a phase 3 clinical trial for higher risk MDS, a phase 3 clinical trial for pancreatic cancer and a phase 2 trial for lower risk MDS. The protocols for the clinical trials had been written and provided to Baxter and a Special Protocol Assessment (“SPA”) had already been granted to the Company by the U.S. Food and Drug Administration (“FDA”) for higher risk MDS. These later stage clinical trials, where protocols have been prepared and trials are in process, can be completed more easily by entities other than the Company, as compared to earlier stage clinical trials. The remaining services to be performed by the Company are not proprietary and could be performed by other qualified parties. For example, the Company relies on clinical research organizations (“CROs”) to complete the clinical trials, and Baxter could engage the same or similar CROs to complete the trials on its behalf. Although Baxter is not performing development activities related to rigosertib, Baxter possesses the internal expertise (or a vendor could be hired) to complete the efforts under the rigosertib programs without further assistance from the Company. Baxter develops, manufactures and markets products that save and sustain the lives of people with hemophilia, immune disorders, infectious diseases, kidney disease, trauma, and other chronic and acute medical conditions. As a global, diversified healthcare company, Baxter applies a unique combination of expertise in medical devices, pharmaceuticals and biotechnology to create products that advance patient care worldwide. Baxter employs over 50,000 people, with significant revenues and expenditures for research and development. Baxter has expertise in completing clinical trials, assessing clinical trial results and preparing regulatory filings and has also developed and obtained regulatory and marketing approval in Europe for numerous products used to treat hematologic conditions. Baxter has expertise in rare hematologic conditions, and the Company believes that rigosertib is a natural complement to Baxter’s existing treatments for patients with these conditions. Baxter has the rights and full access to past and future intellectual information in order to obtain regulatory approval of rigosertib in Europe. In connection with the Baxter agreement, the Company licensed to Baxter all information and all patents controlled by the Company necessary for the development, manufacture, use and sale of rigosertib and all present and future formulations and dosages in all present and future therapeutic indications in the licensed territory. Accordingly, given Baxter’s ability to sublicense under the agreement and its ability internally or with outside help to conduct the ongoing development efforts, the Company concluded that the license has stand-alone value. In order to determine if the license can be treated as a separate unit of accounting, the Company also considered whether there is a general right of return associated with the license. The $50,000,000 upfront payment received by the Company is non-refundable; therefore, there is no right of return for the license. As a result, the Company concluded that the license is a separate unit of accounting. The Company was not able to establish vendor-specific objective evidence of selling price or third-party evidence for either the license or the research and development services and instead allocated the arrangement consideration between the license and research and development services based on their relative selling prices using best estimate of selling price (“BESP”). Management developed the BESP of the license using a discounted cash flow model, taking into consideration assumptions including the development and commercialization timeline, discount rate and probability of success. Management utilized a third party valuation specialist to assist with the determination of BESP of the license. Management estimated the selling price of the research and development services using third party costs and a discounted cash flow model. The estimated selling prices utilized assumptions including internal estimates of research and development personnel needed to perform the research and development services; and estimates of expected cash outflows to third parties for services and supplies over the expected period that the services will be performed. The key assumptions in these models included the following market conditions and entity-specific factors: (a) the specific rights provided under the license, (b) the stage of development of rigosertib and estimated remaining development and commercialization timelines, (c) the probability of successfully developing and commercializing rigosertib, (d) the market size including the associated sales figures which generate royalty revenue, (e) cost of goods sold, which was assumed to be a specified percentage of revenues based on estimated cost of goods sold of a typical oncology product, (f) sales and marketing costs, which were based on the costs required to field an oncology sales force and marketing group, including external costs required to promote an oncology product, (g) the expected product life of rigosertib assuming commercialization and (h) the competitive environment. The Company utilized a discount rate of 16%, representing the cost of capital derived from returns on equity for comparable companies. Based on management’s analyses, it was determined that the BESP of the license was $120,000,000 and the BESP of the research and development services was $20,600,000. As noted above, the Company received an up-front payment of $50,000,000 under the Baxter agreement, which represents the allocable agreement consideration. Based on the respective BESPs, this payment was allocated $42,400,000 to the license and $7,600,000 to the research and development services. Since the delivery of the license occurred upon the execution of the Baxter agreement and there was no general right of return, $42,400,000 of the $50,000,000 upfront payment was recognized upon the execution of the Baxter agreement. The portion allocated to research and development services is being recognized over the period of performance on a proportional performance basis through March 31, 2014. Management estimated the period of performance to be the period necessary for completion of the non-contingent obligations to perform research and development services required to advance the three formulations of rigosertib described above. For the three and nine months ended September 30, 2013, the Company recognized $979,000 and $2,435,000, respectively, of research and development revenue under the Baxter agreement. The Company and Baxter have agreed to establish a joint committee to facilitate the governance and oversight of the parties’ activities under the agreements. Management considered whether participation on the joint committee may be a deliverable and determined that it was not a deliverable. Had management considered participation on the joint committee as a deliverable, it would not have had a material impact on the accounting for the arrangement based on the analysis of the estimated selling price of such participation. As noted above, in July 2012, Baxter purchased Series J Preferred Stock. Because the Series J Preferred Stock was acquired within several months of the Baxter development and license agreement, management considered whether the Preferred Stock was issued at fair value and if not, whether the consideration received for the Preferred Stock ($50,000,000) or for the collaboration and license agreement ($50,000,000) should be allocated in the financial statements in a manner differently than the prices stated in the agreements. Management, with the assistance of an outside valuation specialist, determined that the price paid by Baxter for the Series J Preferred Stock approximated its fair value, and therefore the consideration received under the agreements was allocated in accordance with terms of the individual agreements. SymBio Agreement In July 2011, the Company entered into a license agreement with SymBio, as subsequently amended, granting SymBio an exclusive, royalty-bearing license for the development and commercialization of rigosertib in Japan and Korea. Under the SymBio license agreement, SymBio is obligated to use commercially reasonable efforts to develop and obtain market approval for rigosertib inside the licensed territory and the Company has similar obligations outside of the licensed territory. The Company has also entered into an agreement with SymBio providing for it to supply SymBio with development-stage product. Under the SymBio license agreement, the Company also agreed to supply commercial product to SymBio under specified terms that will be included in a commercial supply agreement to be negotiated prior to the first commercial sale of rigosertib. The supply of development-stage product and the supply of commercial product will be at the Company’s cost plus a defined profit margin. Sales of development-stage product have been de minimis. The Company has additionally granted SymBio a right of first negotiation to license or obtain the rights to develop and commercialize compounds having a chemical structure similar to rigosertib in the licensed territory. Under the terms of the SymBio license agreement, the Company received an upfront payment of $7,500,000. The Company is eligible to receive milestone payments of up to an aggregate of $33,000,000 from SymBio upon the achievement of specified development and regulatory milestones for specified indications. Of the development milestones, $3,000,000 is due after enrollment of the first patient in the event a decision is made, after the Company’s interim analysis, to start a phase 3 clinical trial of rigosertib IV in combination with gemcitabine for pancreatic cancer patients in the United States. Of the regulatory milestones, $5,000,000 is due upon receipt of marketing approval in the United States for rigosertib IV in higher risk MDS patients, $3,000,000 is due upon receipt of marketing approval in Japan for rigosertib IV in higher risk MDS patients, $5,000,000 is due upon receipt of marketing approval in the United States for rigosertib Oral in lower risk MDS patients, $5,000,000 is due upon receipt of marketing approval in Japan for rigosertib Oral in lower risk MDS patients, $5,000,000 is due upon receipt of marketing approval in the United States for rigosertib IV in combination with gemcitabine in pancreatic cancer patients, and $3,000,000 is due upon receipt of marketing approval in Japan for rigosertib IV in combination with gemcitabine for pancreatic cancer patients. Furthermore, upon receipt of marketing approval in the United States and Japan for an additional indication of rigosertib, which we are currently not pursuing, an aggregate of $4,000,000 would be due. In addition to these pre-commercial milestones, the Company is eligible to receive tiered milestone payments based upon annual net sales of rigosertib by SymBio of up to an aggregate of $30,000,000. Further, under the terms of the SymBio license agreement, SymBio will make royalty payments to the Company at percentage rates ranging from the mid-teens to 20% based on net sales of rigosertib by SymBio. Royalties will be payable under the SymBio agreement on a country-by-country basis in the licensed territory, until the later of the expiration of marketing exclusivity in those countries, a specified period of time after first commercial sale of rigosertib in such country, or the expiration of all valid claims of the licensed patents covering rigosertib or the manufacture or use of rigosertib in such country. If no valid claim exists covering the composition of matter of rigosertib or the use of or treatment with rigosertib in a particular country before the expiration of the royalty term, and specified competing products achieve a specified market share percentage in such country, SymBio’s obligation to pay the Company royalties will continue at a reduced royalty rate until the end of the royalty term. In addition, the applicable royalties payable to the Company may be reduced if SymBio is required to pay royalties to third-parties for licenses to intellectual property rights necessary to develop, use, manufacture or commercialize rigosertib in the licensed territory. The license agreement with SymBio will remain in effect until the expiration of the royalty term. However, the SymBio license agreement may be terminated earlier due to the uncured material breach or bankruptcy of a party, or force majeure. If SymBio terminates the license agreement in these circumstances, its licenses to rigosertib will survive, subject to SymBio’s milestone and royalty obligations, which SymBio may elect to defer and offset against any damages that may be determined to be due from the Company. In addition, the Company may terminate the license agreement in the event that SymBio brings a challenge against it in relation to the licensed patents, and SymBio may terminate the license agreement without cause by providing the Company with written notice within a specified period of time in advance of termination. The Company determined that the deliverables under the SymBio agreement include the exclusive, royalty-bearing, sublicensable license to rigosertib, the research and development services to be provided by the Company and its obligation to serve on a joint committee. The Company concluded that the license did not have standalone value to SymBio and was not separable from the research and development services, because of the uncertainty of SymBio’s ability to develop rigosertib in the SymBio territory on its own and the uncertainty of SymBio’s ability to sublicense rigosertib and recover a substantial portion of the original upfront payment of $7,500,000 paid by SymBio to the Company. The supply of rigosertib for SymBio’s commercial requirements is contingent upon the receipt of regulatory approvals to commercialize rigosertib in Japan and Korea. Because the Company’s commercial supply obligation was contingent upon the receipt of future regulatory approvals, and there were no binding commitments or firm purchase orders pending for commercial supply at or near the execution of the agreement, the commercial supply obligation is deemed to be contingent and is not valued as a deliverable under the SymBio agreement. If SymBio orders the supplies from the Company, the Company expects the pricing for this supply to equal its third-party manufacturing cost plus a pre-negotiated percentage, which will not result in a significant incremental discount to market rates. Due to the lack of standalone value for the license, research and development services, and joint committee obligation, the upfront payment is being recognized ratably using the straight line method through December 2027, the expected term of the agreement. For each of the three and nine months ended September 30, 2013 and 2012, the Company recognized revenues of $113,000 and $341,000, respectively, under this agreement. In addition, the Company recognized revenues related to the supply agreement with SymBio in the amounts of $23,000 and $38,000 for the three months ended September 30, 2013 and 2012, respectively, and $47,000 and $48,000 for the nine months ended September 30, 2013 and 2012, respectively.

Joint Venture	9 Months Ended
Joint Venture	Sep. 30, 2013
Joint Venture
Joint Venture	10. Joint Venture In December 2012, the Company agreed to create a joint venture with GVK BIO. The resulting joint venture, GBO was formed on April 1, 2013. The purpose of GBO is to collaborate on and develop two new programs through filing of an investigational new drug application and/or conducting proof of concept studies using the Company’s technology platform. As of September 30, 2013, the Company consolidated 100% of GBO since GVK BIO had not made any capital contributions to the joint venture.

- Definition

The entire disclosure for equity method investments and joint ventures. Equity method investments are investments that give the investor the ability to exercise significant influence over the operating and financial policies of an investee. Joint ventures are entities owned and operated by a small group of businesses as a separate and specific business or project for the mutual benefit of the members of the group.

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Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2013
Income Taxes
Income Taxes	11. Income Taxes For the three and nine months ended September 30, 2013, the Company recorded $432,000 of income tax expense. The income tax expense represents US federal alternative minimum tax of $190,000 and state income taxes of $292,000, for the year ended December 31, 2012. Federal and state taxable income for the year ended December 31, 2012 was partially offset by net operating loss carryforwards. Other than the $432,000 of income tax expense for the year ended December 31, 2012, the Company did not recognize any consolidated income tax benefit (expense) for the three and nine month periods ended September 30, 2013 and 2012. The Company has recorded a valuation allowance to reduce its net deferred tax asset to an amount that is more likely than not to be realized in future years. Accordingly, the benefit of the net operating loss that would have been recognized was offset by changes in the valuation allowance. During the nine months ended September 30, 2013, the Company had no material changes in uncertain tax positions.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

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Initial Public Offering	9 Months Ended
Initial Public Offering	Sep. 30, 2013
Initial Public Offering
Initial Public Offering	12. Initial Public Offering On July 24, 2013, the Company’s Registration Statement was declared effective by the SEC, and on July 25, 2013, the Company’s Common Stock began trading on the NASDAQ Global Market under the symbol ONTX. On July 30, 2013, immediately prior to the consummation of the IPO, all outstanding shares of Preferred Stock automatically converted into shares of Common Stock at the applicable conversion ratio then in effect. As a result of the conversion, as of September 30, 2013, the Company had no shares of Preferred Stock outstanding. On July 30, 2013, the Company completed the IPO. The Company received net proceeds of $79,811,000 from the IPO, net of underwriting discounts and commissions and other estimated offering expenses. In preparation for the IPO, the Company’s board of directors and stockholders approved a one-for-1.333 reverse stock split of the Company’s Common Stock. The reverse stock split became effective on July 17, 2013. All Common Stock share and per share amounts in the condensed consolidated financial statements and notes thereto have been retroactively adjusted for all periods presented to give effect to this reverse stock split, including reclassifying an amount equal to the reduction in par value of common stock to additional paid-in capital. The reverse stock split did not result in a retroactive adjustment of share amounts for the Preferred Stock. In addition, in July 2013, the Company’s board of directors and stockholders approved an amendment of the Company’s certificate of incorporation to, among other things, change the definition of a designated public offering to remove the per share price requirement and to set the threshold at gross proceeds to the Company of at least $25.0 million.

Related-Party Transactions	9 Months Ended
Related-Party Transactions	Sep. 30, 2013
Related-Party Transactions
Related-Party Transactions	13. Related-Party Transactions The Company has entered into a research agreement, as subsequently amended, with the Mount Sinai School of Medicine (“Mount Sinai”), with which a member of its board of directors and a significant stockholder is affiliated. Mount Sinai is undertaking research on behalf of the Company on the terms set forth in the agreements. Mount Sinai, in connection with the Company, will prepare applications for patents generated from the research. Results from all projects will belong exclusively to Mount Sinai, but the Company will have an exclusive option to license any inventions. Payments to Mount Sinai for the three months ended September 30, 2013 and 2012 were $420,000 and $190,000, respectively and for the nine months ended September 30, 2013 and 2012 were $645,000 and $659,000, respectively. At September 30, 2013 and 2012, the Company owed Mount Sinai $295,000 and $190,000, respectively, which is included in accounts payable on the consolidated balance sheets. The Company outsources the synthesis of some of its chemical compounds to vendors in the United States and in foreign countries. A supplier, of which a member of the Company’s board of directors and a significant stockholder is an owner, produces one of these compounds under contract. The Company’s aggregate payments for these services for the three months ended September 30, 2013 and 2012 were $0 and $104,000, respectively and for the nine months ended September 30, 2013 and 2012 were $107,000 and $157,000, respectively. At September 30, 2013 and 2012, the Company owed this supplier $0 and $92,000, respectively, which is included in accounts payable on the consolidated balance sheets. The Company purchases chemical compounds from corporations owned by a former member of its board of directors. The Company’s aggregate payments to these suppliers for the three months ended September 30, 2013 and 2012 were $371,000 and $76,000, respectively and for the nine months ended September 30, 2013 and 2012 were $611,000 and $528,000, respectively. At September 30, 2013 and 2012, the Company owed this supplier $14,000 and $58,000, respectively, which is included in accounts payable on the consolidated balance sheets. The Company also rents office space in Pennington, New Jersey from a corporation related to these suppliers and affiliated with the former member of our board of directors.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

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Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2013
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The condensed consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States (“GAAP”) for interim financial information. Certain information and footnotes normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). The financial statements include the consolidated accounts of the Company, its wholly-owned subsidiary, Onconova Europe GmbH and its joint venture, GBO, LLC. All significant intercompany transactions have been eliminated.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of September 30, 2013, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2013 and 2012, the condensed consolidated statements of redeemable convertible preferred stock and stockholders’ deficit and the condensed consolidated statements of cash flows for the nine months ended September 30, 2013 and 2012 are unaudited. The interim unaudited condensed consolidated financial statements have been prepared on the same basis as the annual audited consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of September 30, 2013 and the results of its operations, its comprehensive loss and its cash flows for the nine months ended September 30, 2013 and 2012. The financial data and other information disclosed in these notes related to the nine months ended September 30, 2013 and 2012 are unaudited. The results for the nine months ended September 30, 2013 are not necessarily indicative of results to be expected for the year ending December 31, 2013, any other interim periods, or any future year or period. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto for the year ended December 31, 2012 included in the Company’s final prospectus filed on July 25, 2013 with the SEC pursuant to Rule 424(b)(4) of the Securities Act of 1933, as amended (the “Securities Act”).
Segment Information	Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one segment, which is the identification and development of oncology therapeutics.
Significant Accounting Policies	Significant Accounting Policies The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2012 included in the Company’s final prospectus filed on July 25, 2013 with the SEC pursuant to Rule 424(b)(4) of the Securities Act. Since the date of such financial statements, there have been no changes to the Company’s significant accounting policies.
Foreign Currency Translation	Foreign Currency Translation The reporting currency of the Company and its U.S. subsidiary is the U.S. dollar. The functional currency of the Company’s non-U.S. subsidiary is the local currency. Assets and liabilities of the foreign subsidiary are translated into U.S. dollars based on exchange rates at the end of the period. Revenues and expenses are translated at average exchange rates during the reporting period. Gains and losses arising from the translation of assets and liabilities are included as a component of accumulated other comprehensive income. Gains and losses resulting from foreign currency transactions are reflected within the Company’s results of operations. The Company has not utilized any foreign currency hedging strategies to mitigate the effect of its foreign currency exposure.
Marketable Securities	Marketable Securities Marketable securities with original maturities longer than three months but which mature in less than one year from the balance sheet date are classified as current assets. Marketable securities that mature more than one year from the balance sheet date are classified as noncurrent assets. Marketable securities that the Company has the intent and ability to hold to maturity are classified as investments held-to-maturity and are reported at amortized cost. The difference between the acquisition cost and face values of held-to-maturity investments is amortized over the remaining term of the investments and added to or subtracted from the acquisition cost and interest income. As of September 30, 2013, all of the Company’s investments were classified as held-to-maturity.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2013, the Financial Accounting Standards Board (the “FASB”) amended its guidance to require an entity to present the effect of certain significant reclassifications out of accumulated other comprehensive income on the respective line items in net income. The new accounting guidance does not change the items that must be reported in other comprehensive income or when an item of other comprehensive income must be reclassified to net income. The guidance is effective prospectively for fiscal years beginning after December 15, 2012. The Company adopted these new provisions for the quarter beginning January 1, 2013. As the guidance requires additional presentation only, there was no impact to the Company’s consolidated financial position, results of operations or cash flows. In July 2013, the FASB issued guidance clarifying that an unrecognized tax benefit, or a portion of an unrecognized tax benefit, should be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward if such settlement is required or expected in the event the uncertain tax benefit is disallowed. In situations where a net operating loss carryforward, a similar tax loss, or a tax credit carryforward is not available at the reporting date under the tax law of the applicable jurisdiction or the tax law of the jurisdiction does not require, and the entity does not intend to use, the deferred tax asset for such purpose, the unrecognized tax benefit should be presented in the financial statements as a liability and should not be netted with the deferred tax asset. The guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2013. Early adoption is permitted. The guidance is to be applied prospectively to all unrecognized tax benefits that exist at the effective date. Retrospective application is permitted. The Company is currently evaluating the impact that adoption will have on the determination or reporting of its financial results.

- Definition

Disclosure of accounting policy for (1) transactions denominated in a currency other than the reporting enterprise's functional currency, (2) translating foreign currency financial statements that are incorporated into the financial statements of the reporting enterprise by consolidation, combination, or the equity method of accounting, and (3) remeasurement of the financial statements of a foreign reporting enterprise in a hyperinflationary economy.

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- Definition

Disclosure of accounting policy for investments in debt and equity securities that have readily determinable fair values (marketable securities). At a minimum, the disclosure might address accounting policies for investments classified as trading, available for sale, or held to maturity and may include how the entity determines whether impairments of available for sale or held to maturity investments are other than temporary, how the fair values of the entity's securities are determined, and the entity's accounting treatment for transfers between investment categories.

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Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2013

Fair Value Measurements

Schedule of financial assets and liabilities measured at fair value on a recurring basis

	Fair Value Measurement as of September 30, 2013								Fair Value Measurement as of December 31, 2012
	Level 1		Level 2		Level 3		Balance		Level 1		Level 2		Level 3		Balance

Warrant liability	$	—	$	—	$	81,000	$	81,000	$	—	$	—	$	62,000	$	62,000
Total	$	—	$	—	$	81,000	$	81,000	$	—	$	—	$	62,000	$	62,000

Schedule of reconciliation of liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3)

	Warrant Liability
Balance at December 31, 2012	$	62,000
Change in fair value upon re-measurement	19,000
Balance at September 30, 2013	$	81,000

- Definition

Tabular disclosure of the fair value measurement of liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and gains or losses recognized in other comprehensive income (loss) and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs) by class of liability.

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Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2013

Marketable Securities

Summary of marketable securities

	September 30, 2013		December 31, 2012

U.S. Treasury obligations	$	39,990,000	$	—

- Definition

Tabular disclosure of all investments in certain debt and equity securities for which the entity has the positive intent and ability to hold until maturity.

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Net Loss Per Share of Common Stock (Tables)

9 Months Ended

Sep. 30, 2013

Net Loss Per Share of Common Stock

Schedule of antidilutive securities which have been excluded from the computation of diluted weighted average shares outstanding

	September 30,
	2013	2012
Preferred Stock	—	12,838,317
Warrants	4,597	4,597
Stock options	3,549,842	2,112,644
	3,554,439	14,955,558

Balance Sheet Detail (Tables)

9 Months Ended

Sep. 30, 2013

Balance Sheet Detail

Schedule of prepaid expenses and other current assets

	September 30,		December 31,
	2013		2012

Research and development	$	2,476,000	$	1,429,000
Manufacturing	1,566,000		—
Insurance	889,000		101,000
Other	395,000		195,000
	$	5,326,000	$	1,725,000

Schedule of property and equipment

	September 30,			December 31,
	2013			2012

Property and equipment	$	2,326,000		$	1,811,000
Accumulated depreciation	(1,674,000		)	(1,348,000		)
	$	652,000		$	463,000

Schedule of accrued expenses and other current liabilities

	September 30,		December 31,
	2013		2012

Research and development	$	4,944,000	$	3,521,000
Employee compensation	2,087,000		247,000
Income taxes	432,000		—
Other	354,000		157,000
	$	7,817,000	$	3,925,000

Preferred Stock and Stockholders' Deficit (Tables)

9 Months Ended

Sep. 30, 2013

Preferred Stock and Stockholders' Deficit

Schedule of composition of share capital

	Authorized		Issued and Outstanding
	September 30,	December 31,	September 30,	December 31,
	2013	2012	2013	2012
Shares of $0.01 par value per share:
Common stock	75,000,000	30,145,155	21,405,905	2,606,484

Series A Preferred Stock	—	400,000	—	107,000
Series B Preferred Stock	—	1,200,000	—	1,107,189
Series C Preferred Stock	—	1,200,000	—	1,069,946
Series D Preferred Stock	—	1,625,000	—	1,583,568
Series E Preferred Stock	—	1,650,000	—	1,633,082
Series F Preferred Stock	—	2,000,000	—	2,000,000
Series G Preferred Stock	—	2,700,000	—	1,934,359
Series H Preferred Stock	—	2,042,950	—	2,013,424
Series I Preferred Stock	—	2,700,000	—	2,433,328
Series J Preferred Stock	—	3,030,303	—	3,030,303
Total Preferred Stock	—	18,548,253	—	16,912,199

Schedule of activity of the Preferred Stock

	December 31, 2012		Issuance of Preferred Stock		Exercise of warrants		Accretion of redemption premium and issuance costs on Preferred Stock		Conversion of Preferred Stock into Common Stock			September 30, 2013
Series A
Shares	107,000		—		—		—		(107,000		)	—
Amount	$	535,000	$	—	$	—	$	—	$	(535,000	)	$	—
Series B
Shares	1,107,189		—		—		—		(1,107,189		)	—
Amount	$	12,733,000	$	—	$	—	$	—	$	(12,733,000	)	$	—
Series C
Shares	1,069,946		—		—		—		(1,069,946		)	—
Amount	$	7,618,000	$	—	$	—	$	—	$	(7,618,000	)	$	—
Series D
Shares	1,583,568		—		—		—		(1,583,568		)	—
Amount	$	18,211,000	$	—	$	—	$	—	$	(18,211,000	)	$	—
Series E
Shares	1,633,082		—		—		—		(1,633,082		)	—
Amount	$	18,780,000	$	—	$	—	$	—	$	(18,780,000	)	$	—
Series F
Shares	2,000,000		—		—		—		(2,000,000		)	—
Amount	$	23,000,000	$	—	$	—	$	—	$	(23,000,000	)	$	—
Series G
Shares	1,934,359		—		—		—		(1,934,359		)	—
Amount	$	22,819,000	$	—	$	—	$	—	$	(22,819,000	)	$	—
Series H
Shares	2,013,424		—		—		—		(2,013,424		)	—
Amount	$	22,005,000	$	—	$	—	$	868,000	$	(22,873,000	)	$	—
Series I
Shares	2,433,328		—		—		—		(2,433,328		)	—
Amount	$	26,933,000	$	—	$	—	$	226,000	$	(27,159,000	)	$	—
Series J
Shares	3,030,303		—		—		—		(3,030,303		)	—
Amount	$	48,681,000	$	—	$	—	$	1,226,000	$	(49,907,000	)	$	—
Total
Shares	16,912,199		—		—		—		(16,912,199		)	—
Amount	$	201,315,000	$	—	$	—	$	2,320,000	$	(203,635,000	)	$	—

- Definition

Tabular disclosure of temporary equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

+ References+ Details

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2013

Stock-Based Compensation

Schedule of shares reserved for issuance under the 2013 Plan

	September 30,		December 31,
	2013	2012	2012	2011
Shares of Common Stock reserved for issuance under the 2013 Plan	6,107,831	4,107,831	4,107,831	3,046,975

Schedule of stock option activity

					Weighted-
					Average
			Weighted-		Remaining
			Average		Contractual
	Number of		Exercise		Term
	Options		Price		(in years)
Outstanding at December 31, 2012	2,564,147		$	8.10	7.52
Granted	1,095,840		14.62
Exercised	(19,627	)	2.62
Forfeited	(90,518	)	12.89
Outstanding at September 30, 2013	3,549,842		$	10.01	7.79

Vested or expected to vest at September 30, 2013	3,549,842		$	10.01	7.79
Exercisable at September 30, 2013	2,175,739		$	7.97	6.84

Schedule of roll forward of the stock option liability

Balance at December 31, 2012	$	11,967,000
Change in fair value upon remeasurement	2,553,000
Settlements of option liability awards	(38,000		)
Stock option award modification	(14,482,000		)
Balance at September 30, 2013	$	—

Schedule of options granted to purchase shares of Common Stock

During the period from April 23, 2013 through September 30, 2013, the Company granted options to purchase shares of its Common Stock as follows:

Shares	Exercise Price
3,900	$	14.74
752,000	$	15.00
17,500	$	21.79

Schedule of stock-based compensation expense

	Quarter Ended September 30,				Nine Months Ended September 30,
	2013		2012		2013		2012

General and administrative	$	2,821,000	$	5,559,000	$	4,347,000	$	6,880,000
Research and development	1,275,000		5,131,000		2,592,000		6,351,000
	$	4,096,000	$	10,690,000	$	6,939,000	$	13,231,000

Schedule of information with respect to stock options outstanding and exercisable

Information with respect to stock options outstanding and exercisable at September 30, 2013 is as follows:

			Weighted
			Average
			Remaining
Exercise			Contractual
Price		Shares	Life (years)	Exercisable
$	1.33	149,987	0.84	149,987
2.67		65,207	2.32	65,207
5.76		396,941	6.44	378,063
6.00		415,267	3.93	415,267
6.13		592,906	6.66	506,444
7.53		49,982	6.31	35,410
13.28		1,105,252	9.33	252,497
14.74		4,800	9.66	4,800
15.00		752,000	9.82	368,064
21.79		17,500	9.82	—
		3,549,842	6.84	2,175,739

Nature of Business (Details) (USD $)	0 Months Ended	3 Months Ended		9 Months Ended
Nature of Business (Details) (USD $)	Jul. 30, 2013	Sep. 30, 2013 item	Sep. 30, 2012	Sep. 30, 2013 item	Sep. 30, 2012	Apr. 30, 2013 item	Dec. 31, 2012
Nature of Business
Number of clinical-stage product candidates		3		3
Number of preclinical programs		6		6
Number of clinical programs developed by GBO, LLC						2
Net loss		$ (20,521,000)	$ (1,435,000)	$ (47,928,000)	$ (19,650,000)
Accumulated deficit		(216,281,000)		(216,281,000)			(168,353,000)
Preferred stock, par value per share (in dollars per share)		$ 0.01		$ 0.01			$ 0.01
Number of series denominated as Series A through Series J preferred stock				10
Initial Public Offering
Common stock, par value (in dollars per share)		$ 0.01		$ 0.01			$ 0.01
Net proceeds received from the sale, net of underwriting discounts and commissions and other estimated offering expenses	79,811,000			79,811,000
Preferred stock outstanding (in shares)	0	0		0			16,912,199
IPO
Initial Public Offering
Number of shares issued in initial public offering	5,941,667
Common stock, par value (in dollars per share)	$ 0.01
Price per share (in dollars per share)	$ 15.00
Number of shares issued pursuant to an option granted to the underwriters to cover over-allotments	775,000
Net proceeds received from the sale, net of underwriting discounts and commissions and other estimated offering expenses	$ 79,811,000

Fair Value Measurements (Details) (USD $)	9 Months Ended	12 Months Ended
Fair Value Measurements (Details) (USD $)	Sep. 30, 2013 item	Dec. 31, 2012
Fair Value Measurements
Fair value material re-measurements	$ 0	$ 0
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option pricing model
Number of group companies of which average historical share price trading data used for estimation of volatility	11
Financial assets and liabilities measured at fair value
Amount of transfers of assets out of Level 1 into Level 2	0	0
Amount of transfers of assets out of Level 2 into Level 1	0	0
Amount of transfers of liabilities out of Level 1 into Level 2	0	0
Amount of transfers of liabilities out of Level 2 into Level 1	0	0
Warrants
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option pricing model
Dividend yield (as a percent)	0.00%	0.00%
Weighted average volatility (as a percent)	73.93%	64.87%
Warrants \| Weighted average
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option pricing model
Weighted average risk-free interest rate (as a percent)	0.40%	0.31%
Recurring basis
Financial assets and liabilities measured at fair value
Warrant liability	81,000	62,000
Total	81,000	62,000
Recurring basis \| Level 3
Financial assets and liabilities measured at fair value
Warrant liability	81,000	62,000
Total	$ 81,000	$ 62,000

Fair Value Measurements (Details 2) (Warrants, USD $)	9 Months Ended
Fair Value Measurements (Details 2) (Warrants, USD $)	Sep. 30, 2013
Warrants
Reconciliation of the warrant liability measured at fair value
Balance at the beginning of the period	$ 62,000
Change in fair value upon re-measurement	19,000
Balance at the end of the period	$ 81,000

Marketable Securities (Details) (USD $)	Sep. 30, 2013
Marketable securities, current
Marketable securities	$ 39,990,000
U.S. Treasury obligations
Marketable securities, current
Marketable securities	$ 39,990,000

Net Loss Per Share of Common Stock (Details)	9 Months Ended
Net Loss Per Share of Common Stock (Details)	Sep. 30, 2013	Sep. 30, 2012
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares as they would be antidilutive
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares	3,554,439	14,955,558
Preferred Stock
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares as they would be antidilutive
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares		12,838,317
Warrants
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares as they would be antidilutive
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares	4,597	4,597
Stock options
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares as they would be antidilutive
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares	3,549,842	2,112,644

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References+ Details

Balance Sheet Detail (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Prepaid expenses and other current assets:
Research and development	$ 2,476,000	$ 1,429,000
Manufacturing	1,566,000
Insurance	889,000	101,000
Other	395,000	195,000
Total	5,326,000	1,725,000
Property and equipment:
Property and equipment	2,326,000	1,811,000
Accumulated depreciation	(1,674,000)	(1,348,000)
Total	652,000	463,000
Accrued expenses and other current liabilities:
Research and development	4,944,000	3,521,000
Employee compensation	2,087,000	247,000
Income taxes	432,000
Other	354,000	157,000
Accrued expenses and other current liabilities	$ 7,817,000	$ 3,925,000

Preferred Stock and Stockholders' Deficit (Details) (USD $)	0 Months Ended		3 Months Ended		9 Months Ended			3 Months Ended	9 Months Ended	1 Months Ended	9 Months Ended		9 Months Ended			9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended		1 Months Ended		9 Months Ended
	Jul. 30, 2013 item	Jul. 17, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2013 Series G Preferred Stock Warrant	Sep. 30, 2013 Series G Preferred Stock Warrant	Jul. 31, 2012 Convertible promissory notes	Sep. 30, 2013 Preferred stock	Dec. 31, 2012 Preferred stock	Sep. 30, 2013 Preferred stock Minimum item	Sep. 30, 2013 Series A Preferred Stock	Dec. 31, 2012 Series A Preferred Stock	Sep. 30, 2013 Series B Preferred Stock	Dec. 31, 2012 Series B Preferred Stock	Sep. 30, 2013 Series C Preferred Stock	Dec. 31, 2012 Series C Preferred Stock	Sep. 30, 2013 Series D Preferred Stock	Dec. 31, 2012 Series D Preferred Stock	Sep. 30, 2013 Series E Preferred Stock	Dec. 31, 2012 Series E Preferred Stock	Sep. 30, 2013 Series F Preferred Stock	Dec. 31, 2012 Series F Preferred Stock	Sep. 30, 2013 Series G Preferred Stock	Dec. 31, 2012 Series G Preferred Stock	Sep. 30, 2013 Series H Preferred Stock	Dec. 31, 2012 Series H Preferred Stock	Sep. 30, 2013 Series I Preferred Stock	Dec. 31, 2012 Series I Preferred Stock	Jul. 31, 2012 Series I Preferred Stock Convertible promissory notes	Jul. 31, 2012 Series J Preferred Stock	Sep. 30, 2013 Series J Preferred Stock	Dec. 31, 2012 Series J Preferred Stock
Preferred stock and stockholders' deficit
Gross proceeds from issuance of shares of preferred stock																																	$ 50,000,000
Shares of preferred stock issued			0		0		16,912,199					16,912,199			107,000		1,107,189		1,069,946		1,583,568		1,633,082		2,000,000		1,934,359		2,013,424		2,433,328				3,030,303
Reverse stock split of common stock		0.75
Number of shares of preferred stock issued upon conversion of note																																2,433,328
Principal amount of the notes converted										26,444,000
Accrued interest										323,000
Issue price (in dollars per share)														$ 5.00		$ 5.75		$ 3.56		$ 4.67		$ 9.76		$ 11.00		$ 9.79		$ 9.79		$ 11.00		$ 11.00	$ 16.50	$ 16.50
Number of shares of preferred stock issued																																	3,030,303
Issuance costs associated with offering																																	2,204,000
Composition of share capital
Common stock, par value per share (in dollars per share)			$ 0.01		$ 0.01		$ 0.01
Common stock authorized (in shares)			75,000,000		75,000,000		30,145,155
Common stock issued (in shares)			21,405,905		21,405,905		2,606,484
Common stock outstanding (in shares)			21,405,905		21,405,905		2,606,484
Preferred stock authorized (in shares)			0		0		18,548,253					18,548,253			400,000		1,200,000		1,200,000		1,625,000		1,650,000		2,000,000		2,700,000		2,042,950		2,700,000				3,030,303
Preferred stock issued (in shares)			0		0		16,912,199					16,912,199			107,000		1,107,189		1,069,946		1,583,568		1,633,082		2,000,000		1,934,359		2,013,424		2,433,328				3,030,303
Preferred stock outstanding (in shares)	0		0		0
Activity of the preferred stock
Balance at the beginning of the period (in shares)					16,912,199						16,912,199			107,000		1,107,189		1,069,946		1,583,568		1,633,082		2,000,000		1,934,359		2,013,424		2,433,328				3,030,303
Balance at the beginning of the period											201,315,000			535,000		12,733,000		7,618,000		18,211,000		18,780,000		23,000,000		22,819,000		22,005,000		26,933,000				48,681,000
Issuance of Preferred Stock (in shares)																																	3,030,303
Accretion of redemption premium and issuance costs on Preferred Stock					(2,320,000)	(2,943,000)					2,320,000																	868,000		226,000				1,226,000
Conversion of convertible preferred stock into common stock (in shares)											(16,912,199)			(107,000)		(1,107,189)		(1,069,946)		(1,583,568)		(1,633,082)		(2,000,000)		(1,934,359)		(2,013,424)		(2,433,328)				(3,030,303)
Conversion of convertible preferred stock into common stock					203,635,000						(203,635,000)			(535,000)		(12,733,000)		(7,618,000)		(18,211,000)		(18,780,000)		(23,000,000)		(22,819,000)		(22,873,000)		(27,159,000)				(49,907,000)
Balance at the end of the period (in shares)	0		0		0
Number of voting rights per share of common stock for each holder of preferred stock	1
Number of shares of common stock issued for each share of preferred stock														0.80		0.85		0.75		0.75		0.75		0.77		0.75		0.75		0.75				0.75
Percentage of holding of outstanding Series A, Series B and Series C Preferred Stock holders from whom the written request required for redemption at specified price													66.67%
Redemption price (in dollars per share)														$ 5.00		$ 11.50		$ 7.12		$ 11.50		$ 11.50		$ 11.50		$ 11.50		$ 11.50		$ 11.50				$ 18.00
Number of days after receipt of the written request for redemption considered for determining redemption date											60 days
Number of series of preferred stock contemporaneously subject to redemption considered for following liquidation order of priority													1
Number of warrants issued (in shares)								6,128	6,128
Ratio of the number of warrants issued for each share of preferred stock purchased								0.50	0.50
Weighted average assumptions
Exercise price (in dollars per share)								$ 9.79	$ 9.79
Share price (in dollars per share)								$ 9.79	$ 9.79
Expected term									3 years
Risk-free rate (as a percent)									1.52%
Volatility (as a percent)									85.46%
Change in fair value of warrant liability			$ (31,000)	$ (25,000)	$ (19,000)	$ 365,000		$ (31,000)	$ (19,000)
Warrants outstanding immediately prior to IPO								6,128	6,128
Preferred Stock warrants converted into common stock warrants (in shares)									4,597
Common stock warrants, reverse stock split									0.750

Stock-Based Compensation (Details) (USD $)	3 Months Ended		9 Months Ended		177 Months Ended			0 Months Ended	5 Months Ended	9 Months Ended	12 Months Ended	5 Months Ended			1 Months Ended	0 Months Ended		5 Months Ended	9 Months Ended
Stock-Based Compensation (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011	Apr. 23, 2013 Stock options	Sep. 30, 2013 Stock options	Sep. 30, 2013 Stock options	Dec. 31, 2012 Stock options	Sep. 30, 2013 Stock options Exercise Price $14.74	Sep. 30, 2013 Stock options Exercise Price $15.00	Sep. 30, 2013 Stock options Exercise Price $21.79	Jan. 31, 2008 Stock options 2007 Plan	Jul. 25, 2013 Stock options 2013 Plan	Jul. 31, 2013 Stock options 2013 Plan	Sep. 30, 2013 Stock options Maximum	Sep. 30, 2013 Stock options Maximum
Stock-based compensation
Percentage of increase in number of shares reserved for issuance under the 2007 Plan equal to fully diluted shares calculated annually															17.00%
Shares of common stock reserved for issuance under the 2013 Plan	6,107,831	4,107,831	6,107,831	4,107,831	6,107,831	4,107,831	3,046,975										6,107,831
Number of shares of Common Stock available for future issuance																	1,532,336
Number of shares of stock options issued in conjunction with the IPO																485,500
Vesting period																			4 years
Expiration period																			10 years
Number of Options
Balance at the beginning of the period (in shares)										2,564,147
Granted (in shares)										1,095,840		3,900	752,000	17,500
Exercised (in shares)										(19,627)
Forfeited (in shares)										(90,518)
Balance at the end of the period (in shares)									3,549,842	3,549,842	2,564,147
Vested or expected to vest at the end of the period (in shares)									3,549,842	3,549,842
Exercisable at the end of the period (in shares)									2,175,739	2,175,739
Weighted-Average Exercise Price
Balance at the beginning of the period (in dollars per share)										$ 8.10
Granted (in dollars per share)										$ 14.62		$ 14.74	$ 15.00	$ 21.79
Exercised (in dollars per share)										$ 2.62
Forfeited (in dollars per share)										$ 12.89
Balance at the end of the period (in dollars per share)									$ 10.01	$ 10.01	$ 8.10
Vested or expected to vest at the end of the period (in dollars per share)									$ 10.01	$ 10.01
Exercisable at the end of the period (in dollars per share)									$ 7.97	$ 7.97
Average Remaining Contractual Term
Outstanding at the beginning of the period										7 years 9 months 14 days	7 years 6 months 7 days
Outstanding at the end of the period										7 years 9 months 14 days	7 years 6 months 7 days
Vested or expected to vest at the end of the period										7 years 9 months 14 days
Exercisable at the end of the period										6 years 10 months 2 days
Additional disclosures
Grant date intrinsic value of awards granted (in dollars per share)										$ 0.00
Minimum period for which common stock to be held by option holder prior to selling to the significant holder								6 months
Net tax benefits related to the stock-based compensation costs					$ 0
Compensation expense	4,096,000	10,690,000	6,939,000	13,231,000					3,751,000
Stock option liability
Balance at the beginning of the period			11,967,000							11,967,000
Change in fair value upon remeasurement										2,553,000
Settlements of option liability awards										(38,000)
Stock option award modification										(14,482,000)
Balance at the end of the period											$ 11,967,000
Assumptions used to determine fair values for nonemployee options
Dividend yield (as a percent)									0.00%
Contractual life																		5 years 7 months 2 days
Volatility (as a percent)									78.40%
Risk-free interest rate (as a percent)									1.51%

Stock-Based Compensation (Details 2) (USD $)	3 Months Ended		5 Months Ended	9 Months Ended
Stock-Based Compensation (Details 2) (USD $)	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012
Stock-based compensation
Total stock-based compensation	$ 4,096,000	$ 10,690,000		$ 6,939,000	$ 13,231,000
Unrecognized compensation expense of unvested liability awards	2,224,000		2,224,000	2,224,000
Weighted-average period for recognizing unrecognized compensation expense of unvested liability awards				2 years 4 months 6 days
Unrecognized compensation expense related to unvested stock options	3,948,000		3,948,000	3,948,000
Weighted-average period for recognizing unrecognized compensation expense related to unvested stock options			3 years 3 months 29 days
General and administrative
Stock-based compensation
Total stock-based compensation	2,821,000	5,559,000		4,347,000	6,880,000
Research and development
Stock-based compensation
Total stock-based compensation	$ 1,275,000	$ 5,131,000		$ 2,592,000	$ 6,351,000

Stock-Based Compensation (Details 3) (USD $)	9 Months Ended
Stock-Based Compensation (Details 3) (USD $)	Sep. 30, 2013
Options Outstanding
Shares	3,549,842
Weighted Average Remaining Contractual Life	6 years 10 months 2 days
Exercisable
Number (in shares)	2,175,739
Exercise Price $1.33
Stock-based compensation
Exercise Price (in dollars per share)	$ 1.33
Options Outstanding
Shares	149,987
Weighted Average Remaining Contractual Life	10 months 2 days
Exercisable
Number (in shares)	149,987
Exercise Price $2.67
Stock-based compensation
Exercise Price (in dollars per share)	$ 2.67
Options Outstanding
Shares	65,207
Weighted Average Remaining Contractual Life	2 years 3 months 25 days
Exercisable
Number (in shares)	65,207
Exercise Price $5.76
Stock-based compensation
Exercise Price (in dollars per share)	$ 5.76
Options Outstanding
Shares	396,941
Weighted Average Remaining Contractual Life	6 years 5 months 8 days
Exercisable
Number (in shares)	378,063
Exercise Price $6.00
Stock-based compensation
Exercise Price (in dollars per share)	$ 6.00
Options Outstanding
Shares	415,267
Weighted Average Remaining Contractual Life	3 years 11 months 5 days
Exercisable
Number (in shares)	415,267
Exercise Price $6.13
Stock-based compensation
Exercise Price (in dollars per share)	$ 6.13
Options Outstanding
Shares	592,906
Weighted Average Remaining Contractual Life	6 years 7 months 28 days
Exercisable
Number (in shares)	506,444
Exercise Price $7.53
Stock-based compensation
Exercise Price (in dollars per share)	$ 7.53
Options Outstanding
Shares	49,982
Weighted Average Remaining Contractual Life	6 years 3 months 22 days
Exercisable
Number (in shares)	35,410
Exercise Price $13.28
Stock-based compensation
Exercise Price (in dollars per share)	$ 13.28
Options Outstanding
Shares	1,105,252
Weighted Average Remaining Contractual Life	9 years 3 months 29 days
Exercisable
Number (in shares)	252,497
Exercise Price $14.74
Stock-based compensation
Exercise Price (in dollars per share)	$ 14.74
Options Outstanding
Shares	4,800
Weighted Average Remaining Contractual Life	9 years 7 months 28 days
Exercisable
Number (in shares)	4,800
Exercise Price $15.00
Stock-based compensation
Exercise Price (in dollars per share)	$ 15.00
Options Outstanding
Shares	752,000
Weighted Average Remaining Contractual Life	9 years 9 months 25 days
Exercisable
Number (in shares)	368,064
Exercise Price $21.79
Stock-based compensation
Exercise Price (in dollars per share)	$ 21.79
Options Outstanding
Shares	17,500
Weighted Average Remaining Contractual Life	9 years 9 months 25 days

License and Collaboration Agreements (Details) (USD $)	3 Months Ended		9 Months Ended			1 Months Ended	3 Months Ended	9 Months Ended	1 Months Ended									3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended			1 Months Ended		1 Months Ended
License and Collaboration Agreements (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2012 Baxter Maximum item	Sep. 30, 2012 Collaboration arrangement Baxter	Sep. 30, 2013 Collaboration arrangement Baxter	Sep. 30, 2013 Collaboration arrangement Baxter	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter item	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter Maximum	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter Rigosertib intravenous ("IV") in higher risk myelodysplastic syndrome ("MDS") patients	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter Rigosertib intravenous ("IV") in higher risk myelodysplastic syndrome ("MDS") patients Minimum	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter Rigosertib IV in pancreatic cancer patients	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter Rigosertib IV in pancreatic cancer patients Minimum	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter Rigosertib oral in lower risk MDS patients	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter Rigosertib oral in lower risk MDS patients Minimum	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio	Sep. 30, 2013 Collaboration arrangement Rigosertib SymBio	Sep. 30, 2012 Collaboration arrangement Rigosertib SymBio	Sep. 30, 2013 Collaboration arrangement Rigosertib SymBio	Sep. 30, 2012 Collaboration arrangement Rigosertib SymBio	Sep. 30, 2013 Collaboration arrangement Rigosertib SymBio Supply agreement	Sep. 30, 2012 Collaboration arrangement Rigosertib SymBio Supply agreement	Sep. 30, 2013 Collaboration arrangement Rigosertib SymBio Supply agreement	Sep. 30, 2012 Collaboration arrangement Rigosertib SymBio Supply agreement	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio Supply agreement	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio United States and Japan	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio Maximum	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio Rigosertib intravenous ("IV") in higher risk myelodysplastic syndrome ("MDS") patients United States	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio Rigosertib intravenous ("IV") in higher risk myelodysplastic syndrome ("MDS") patients Japan	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio Rigosertib oral in lower risk MDS patients United States	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio Rigosertib oral in lower risk MDS patients Japan	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio Rigosertib IV in combination with gemcitabine for pancreatic cancer patients United States	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio Rigosertib IV in combination with gemcitabine for pancreatic cancer patients Japan
License and collaboration agreements
Number of initial rigosertib indications									3
Upfront payment									$ 50,000,000								$ 7,500,000
Aggregate milestone payments										512,500,000																		33,000,000
Potential pre-commercial milestone payments for successful completion of a Phase 3 clinical trial for indication											50,000,000
Potential pre-commercial milestone payments for joint decisions to proceed with the development of rigosertib for certain indications													25,000,000		25,000,000
Number of joint decisions to proceed with the development of rigosertib for specified indications									2
Potential pre-commercial milestone payments for drug approval application filed for specified indications											25,000,000		25,000,000		25,000,000
Potential milestone payments for regulatory approvals of specified indications										337,500,000		100,000,000		100,000,000		100,000,000
Additional potential pre-commercial milestone payments related to the timing of regulatory approval of indication											20,000,000
Aggregate potential milestone payments based on annual net sales of rigosertib									250,000,000								30,000,000
Percentage of royalty payments based on net sales of rigosertib																	20.00%
Number of employees					50,000
Discount rate (as a percent)						16.00%
BESP of the license						120,000,000
BESP of the research and development services						20,600,000
Up-front payment allocated to license						42,400,000
Up-front payment allocated to research and development services						7,600,000
Allocated up-front payment of license recognized upon execution of agreement						42,400,000
Research and development revenue							979,000	2,435,000
Consideration received for the Preferred Stock						50,000,000
Potential development milestones payments due after enrollment of the first patient in event of decision made to start phase 3 clinical trial of indication																																	3,000,000
Regulatory milestones payments due upon receipt of marketing approval for indication																													5,000,000	3,000,000	5,000,000	5,000,000	5,000,000	3,000,000
Aggregate milestone payments due upon receipt of marketing approval for an additional indication																											4,000,000
Binding commitments																										0
Recognized revenues	$ 1,116,000	$ 42,803,000	$ 2,823,000	$ 43,221,000														$ 113,000	$ 113,000	$ 341,000	$ 341,000	$ 23,000	$ 38,000	$ 47,000	$ 48,000

Income Taxes (Details) (USD $)	3 Months Ended	9 Months Ended	12 Months Ended
Income Taxes (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2012
Income Taxes
Income tax expense for the year ended December 31, 2012 recorded in the current year	$ 432,000	$ 432,000
US federal alternative minimum tax			190,000
State income taxes			292,000
Changes in uncertain tax positions		$ 0

Initial Public Offering (Details) (USD $)	0 Months Ended		9 Months Ended
Initial Public Offering (Details) (USD $)	Jul. 30, 2013	Jul. 17, 2013	Sep. 30, 2013	Jul. 31, 2013	Dec. 31, 2012
Initial Public Offering
Preferred stock outstanding (in shares)	0		0		16,912,199
Net proceeds received from the sale, net of underwriting discounts and commissions and other estimated offering expenses	$ 79,811,000		$ 79,811,000
Reverse stock split of common stock		0.75
Designated public offering amended threshold gross proceeds, minimum				$ 25,000,000

- Definition

The number of securities classified as temporary equity that have been issued and are held by the entity's shareholders. Securities outstanding equals securities issued minus securities held in treasury. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

+ References+ Details

Related-Party Transactions (Details) (USD $)	3 Months Ended		9 Months Ended
Related-Party Transactions (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Mount Sinai
Related-party transactions
Payments to related party	$ 420,000	$ 190,000	$ 645,000	$ 659,000
Amounts due to related party	295,000	190,000	295,000	190,000
Supplier business owned by board members
Related-party transactions
Payments to related party	0	104,000	107,000	157,000
Amounts due to related party	0	92,000	0	92,000
Corporations owned by former board members
Related-party transactions
Payments to related party	371,000	76,000	611,000	528,000
Amounts due to related party	$ 14,000	$ 58,000	$ 14,000	$ 58,000

- Definition

Amount for accounts payable to related parties.

+ References+ Details

Joint Venture (Details)	Sep. 30, 2013	Dec. 31, 2012 item
Joint Venture
Number of new programs to be collaborated and developed		2
Consolidated interest in the joint venture of the entity (as a percent)	100.00%

Summary of Significant Accounting Policies (Details)	9 Months Ended
Summary of Significant Accounting Policies (Details)	Sep. 30, 2013 item
Segment Information
Number of operating segments	1