Stemline Therapeutics (STML) 10-Q 15 May 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	14-May-14
Document and Entity Information	'	'
Entity Registrant Name	'STEMLINE THERAPEUTICS INC	'
Entity Central Index Key	'0001264587	'
Document Type	'10-Q	'
Document Period End Date	31-Mar-14	'
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	'	13,244,232
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'

Balance_Sheets

Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
Current assets:	'	'
Cash and cash equivalents	$24,201,212	$44,200,420
Related party receivable	199,615	199,615
Prepaid expenses and other current assets	1,602,069	292,916
Total current assets	26,002,896	44,692,951
Furniture and fixtures, net	345,000	383,333
Long-term investments	51,444,924	40,204,912
Total assets	77,792,820	85,281,196
Current liabilities:	'	'
Accounts payable and accrued expenses	5,473,072	5,013,808
Total current liabilities	5,473,072	5,013,808
Deferred grant revenue	572,000	643,000
Total liabilities	6,045,072	5,656,808
Stockholders' equity:	'	'
Preferred stock $0.0001 par value, 5,000,000 shares authorized, none issued and outstanding at December 31, 2013 and March 31, 2014	'	'
Common stock $0.0001 par value, 33,750,000 shares authorized at March 31, 2014 and December 31, 2013, 13,235,232 shares issued and outstanding at March 31, 2014 and 13,095,726 shares issued and outstanding at December 31, 2013	1,324	1,310
Additional paid-in capital	112,112,125	111,032,619
Accumulated other comprehensive loss	-9	-43,775
Accumulated deficit during the development stage	-40,365,692	-31,365,766
Total stockholders' equity	71,747,748	79,624,388
Total liabilities and stockholders' equity	$77,792,820	$85,281,196

Balance_Sheets_Parenthetical

Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Balance Sheets	'	'
Preferred stock, par value (in dollars per share)	$0.00	$0.00
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$0.00	$0.00
Common stock, shares authorized	33,750,000	33,750,000
Common stock, shares issued	13,235,232	13,095,726
Common stock, shares outstanding	13,235,232	13,095,726

Statements_of_Operations

Statements of Operations (USD $)	3 Months Ended		128 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014
Revenues:	'	'	'
Grant revenue	$71,000	'	$142,000
Operating expenses:	'	'	'
Research and development	7,116,855	3,161,726	34,741,267
General and administrative	1,988,360	2,167,467	19,344,875
Total operating expenses	9,105,215	5,329,193	54,086,142
Loss from operations	-9,034,215	-5,329,193	-53,944,142
Other income	'	30,649	1,216,205
Other expense	-7,923	-124,713	-17,628
Interest expense	'	-82,389	-813,821
Interest income	42,212	'	1,021,931
Net loss from operations	-8,999,926	-5,505,646	-52,537,455
Less accretion of preferred stock dividends	'	'	-2,591,165
Add discount on redemption of preferred stock	'	'	12,171,765
Net loss attributable to common stockholders	($8,999,926)	($5,505,646)	($42,956,855)
Net loss attributable to common stockholders per common share:	'	'	'
Basic and Diluted (in dollars per share)	($0.70)	($0.90)	'
Weighted-average shares outstanding:	'	'	'
Basic and Diluted (in shares)	12,875,228	6,147,589	'

Statements_of_Comprehensive_Lo

Statements of Comprehensive Loss (USD $)	3 Months Ended		128 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014
Statements of Comprehensive Loss	'	'	'
Net loss	($8,999,926)	($5,505,646)	($52,537,455)
Other comprehensive income (loss):	'	'	'
Unrealized gain (loss) on investments	43,766	'	-9
Other comprehensive gain (loss)	43,766	'	-9
Comprehensive loss	($8,956,160)	($5,505,646)	($52,537,464)

Statement_of_Stockholders_Equi

Statement of Stockholders' Equity (USD $)	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Deficit Accumulated During the Development Stage
Balance at Dec. 31, 2013	$79,624,388	$1,310	$111,032,619	($43,775)	($31,365,766)
Balance (in shares) at Dec. 31, 2013	'	13,095,726	'	'	'
Increase (Decrease) in Stockholders' Equity	'	'	'	'	'
Restricted stock grants	'	13	-13	'	'
Restricted stock grants (in shares)	'	131,248	'	'	'
Forfeiture of restricted stock grants (in shares)	'	-777	'	'	'
Issuance of common stock in connection with the Exercise of stock options	36,953	1	36,952	'	'
Issuance of common stock in connection with the Exercise of stock options (in shares)	'	9,035	'	'	'
Stock-based compensation	1,042,567	'	1,042,567	'	'
Net loss	-8,999,926	'	'	'	-8,999,926
Other comprehensive income	43,766	'	'	43,766	'
Balance at Mar. 31, 2014	$71,747,748	$1,324	$112,112,125	($9)	($40,365,692)
Balance (in shares) at Mar. 31, 2014	'	13,235,232	'	'	'

Statements_of_Cash_Flows

Statements of Cash Flows (USD $)	3 Months Ended		128 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014
Cash flows from operating activities	'	'	'
Net loss	($8,999,926)	($5,505,646)	($52,537,455)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'	'
Depreciation	38,333	0	115,000
Stock-based compensation expense	1,042,567	2,285,187	8,089,320
Non-cash interest expense	'	82,389	391,173
Mark-to-market of put option liability	'	-30,415	-111,420
Beneficial conversion of convertible interest	'	124,570	422,648
Changes in operating assets and liabilities:	'	'	'
Prepaid expenses and other current assets	-1,309,153	-380,537	-1,602,069
Related party receivable	'	'	-199,615
Accounts payable and accrued expenses	459,264	-200,285	5,473,072
Deferred grant revenue	-71,000	'	572,000
Net cash used in operating activities	-8,839,915	-3,624,737	-39,387,346
Cash flows from investing activities	'	'	'
Purchase of furniture and fixtures	'	'	-460,000
Purchase of marketable securities	-11,196,246	'	-71,990,020
Redemption of marketable securities	'	'	20,545,087
Net cash used in investing activities	-11,196,246	'	-51,904,933
Cash flows from financing activities	'	'	'
Proceeds from issuance of preferred stock, net	'	'	12,500,000
Redemption of preferred stock	'	'	-750,000
Proceeds from issuance of common stock, net	'	32,335,483	101,550,788
Proceeds from exercise of stock options	36,953	'	1,330,703
Proceeds from issuance of convertible notes	'	'	862,000
Net cash provided by financing activities	36,953	32,335,483	115,493,491
Net (decrease) increase in cash and cash equivalents	-19,999,208	28,710,746	24,201,212
Cash and cash equivalents at beginning of period	44,200,420	2,025,338	'
Cash and cash equivalents at end of period	24,201,212	30,736,084	24,201,212
Supplemental disclosure of non-cash transactions	'	'	'
Discount on redemption of preferred stock	'	'	12,921,765
Issuance of common stock on redemption of preferred stock	'	'	1,200,000
Accretion of preferred stock dividend	'	'	$1,339,827

Organization_and_Basis_of_Pres

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2014
Organization and Basis of Presentation	'
Organization and Basis of Presentation	'
	1. Organization and Basis of Presentation
	Organization
	Stemline Therapeutics, Inc. (the “Company”) is a clinical-stage biopharmaceutical company focused on discovering, acquiring, developing and commercializing proprietary therapeutics that target both cancer stem cells (“CSCs”) and tumor bulk. The Company’s activities to date have primarily consisted of advancing its two clinical-stage programs, developing its preclinical pipeline, building its proprietary drug discovery platform, fortifying its intellectual property portfolio, identifying and acquiring additional product and technology rights and raising capital. Accordingly, the Company is considered to be in the development stage as defined in Financial Accounting Standards Board Accounting Standards Codification (“ASC”) Topic 915, Development Stage Entities. The Company was incorporated in Delaware on August 8, 2003 (“Inception”) and has its principal office in New York, New York.
	Basis of Presentation
	The accompanying unaudited financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”) and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all information and footnotes required by GAAP for complete financial statements. In the opinion of management, the accompanying financial statements include all adjustments (including normal recurring accruals) considered necessary for fair presentation of the Company’s financial position, results of operations and cash flows for the periods presented. Operating results for the current interim period are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2014 or any future periods. This Form 10-Q should be read in conjunction with the audited financial statements and accompanying notes in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013 (“2013 Form 10-K”). The Company believes that its existing cash, cash equivalents and marketable securities will be sufficient to cover its cash flow requirements for at least the next two years.
	Use of Estimates
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to investments, property and equipment, accrued expenses, share-based compensation and income taxes. The estimates are based on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Results may differ from these estimates due to actual outcomes differing from those on which the Company bases its assumptions.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2014
Summary of Significant Accounting Policies	'
Summary of Significant Accounting Policies	'
	2. Summary of Significant Accounting Policies
	The Company’s significant accounting policies are described in Note 2 of the Notes to the Financial Statements included in the 2013 Form 10-K. There have been no changes to those policies.
	Recently Issued Accounting Pronouncements
	During the quarter ended March 31, 2014, there were no new accounting pronouncements or updates to recently issued accounting pronouncements disclosed in the 2013 Form 10-K, that significantly affect the Company’s present or future results of operations, overall financial condition, liquidity or disclosures.

Prepaid_expenses_and_other_cur

Prepaid expenses and other current assets	3 Months Ended
	Mar. 31, 2014
Prepaid expenses and other current assets	'
Prepaid expenses and other current assets	'
	3. Prepaid expenses and other current assets
	Prepaid expenses and other current assets consist of the following at March 31, 2014 and December 31, 2013:
		March 31,		December 31,
		2014		2013
	Prepaid CRO costs	482,038		39,630
	Prepaid insurance	388,340		43,321
	Deposits	209,965		209,965
	Other prepaid expenses and advances	521,726		—
	Total	$	1,602,069	$	292,916

Furniture_and_Fixtures

Furniture and Fixtures	3 Months Ended
	Mar. 31, 2014
Furniture and Fixtures	'
Furniture and Fixtures	'
	4. Furniture and Fixtures
	Furniture and fixtures consist of the following at March 31, 2014 and December 31, 2013:
		March 31,			December 31,
		2014			2013
	Office furniture and fixtures	$	460,000		$	460,000
	Less accumulated depreciation	(115,000		)	(76,667		)
	Furniture and fixtures, net	$	345,000		$	383,333
	Depreciation expense was 38,333 and zero, respectively, for the three-month periods ended March 31, 2014 and 2013.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2014
Fair Value Measurements	'
Fair Value Measurements	'
	5. Fair Value Measurements
	The Company categorizes its financial instruments into a three-level fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. The fair value hierarchy gives the highest priority to quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). If the inputs used to measure fair value fall within different levels of the hierarchy, the category level is based on the lowest priority level input that is significant to the fair value measurement of the instrument.
	Financial assets recorded at fair value on the Company’s balance sheets are categorized as follows:
	Level 1: Unadjusted quoted prices for identical assets in an active market.
	Level 2: Quoted prices in markets that are not active or inputs that are observable either directly or indirectly for substantially the full-term of the asset. Level 2 inputs include the following:
	·                                          quoted prices for similar assets in active markets,
	·                                          quoted prices for identical or similar assets in non-active markets,
	·                                          inputs other than quoted market prices that are observable, and
	·                                          inputs that are derived principally from or corroborated by observable market data through correlation or other means.
	Level 3: Prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. Level 3 inputs reflect management’s own assessment about the assumptions a market participant would use in pricing the asset.
	There were no transfers between levels in the fair value hierarchy during any period presented herein. The Company’s financial assets and liabilities measured at fair value on a recurring basis at March 31, 2014 and December 31, 2013 consist of the following:
		March 31, 2014
		Quoted
		Prices in
		Active		Significant
		Markets for		Other		Significant			Balance
		Identical		Observable		Unobservable			at
		Assets		Inputs		Inputs			March 31,
		(Level 1)		(Level 2)		(Level 3)			2014
	Assets:
	Cash and cash equivalents	$	24,201,212	$	—	$	—		$	24,201,212
	Long-term investments	51,444,924		—		—			51,444,924
	Total assets at fair value	$	75,646,136	$	—	$	—		$	75,646,136
		December 31, 2013
		Quoted
		Prices in
		Active		Significant
		Markets for		Other		Significant			Balance
		Identical		Observable		Unobservable			at
		Assets		Inputs		Inputs			December 31,
		(Level 1)		(Level 2)		(Level 3)			2013
	Assets:
	Cash and cash equivalents	$	44,200,420	$	—	$	—		$	44,200,420
	Long-term investments	40,204,912		—		—			40,204,912
	Total assets at fair value	$	84,405,332	$	—	$	—		$	84,405,332
	The following is a summary of available-for-sale investments held by the Company at March 31, 2014 and December 31, 2013:
		March 31, 2014
				Gross		Gross			Estimated
		Amortized		Unrealized		Unrealized			Fair
		Cost		Gains		Losses			Value
	Cash equivalents:
	Money market funds	$	22,453,795	$	—	$	—		$	22,453,795
	Long-term investments:
	Fixed-income treasury portfolio:
	Federal home loan bank	17,781,152		1,664		(6,768		)	17,776,048
	Federal farm credit bank	13,876,085		8,656		(5,893		)	13,878,848
	Freddie Mac	14,821,350		3,200		(2,869		)	14,821,681
	Fannie Mae	4,966,346		2,021		(20		)	4,968,347
	Total Long-term investments	51,444,933		15,541		(15,550		)	51,444,924
	Total	$	73,898,728	$	15,541	$	(15,550	)	$	73,898,719
		December 31, 2013
				Gross		Gross			Estimated
		Amortized		Unrealized		Unrealized			Fair
		Cost		Gains		Losses			Value
	Cash equivalents:
	Money market funds	$	41,441,975	$	—	$	—		$	41,441,975
	Long-term investments:
	Fixed-income treasury portfolio:
	Federal home loan bank	13,789,246		—		(14,752		)	13,774,494
	Federal farm credit bank	11,476,874		—		(13,701		)	11,463,173
	Freddie Mac	10,020,626		—		(8,340		)	10,012,286
	Fannie Mae	4,961,941		—		(6,982		)	4,954,959
	Total Long-term investments	40,248,687		—		(43,775		)	40,204,912
Total	$	81,690,662	$	—	$	(43,775	)	$	81,646,887
At March 31, 2014 and December 31, 2013, the remaining contractual maturities of available-for-sale investments classified as current on the balance sheet were less than 12 months, and the remaining contractual maturities of available-for-sale investments classified as long-term were less than two years.
There were no unrealized gains or losses on investments reclassified from accumulated other comprehensive income to other income (expense) in the Statement of Operations for the three-month periods ended March 31, 2014 and 2013.
There were no available-for-sale securities in a continuous unrealized loss position for greater than twelve months at March 31, 2014 and December 31, 2013.
Fair Value of Financial Instruments
The Company’s financial instruments consist principally of cash and cash equivalents, investments, other current assets, accounts payable and accrued expenses. Cash and cash equivalents, and long-term investments are carried at fair value (see above). Financial instruments including other assets, accounts payable and accrued expenses are carried at cost, which approximate fair value given their short-term nature.

Accounts_Payable_and_Accrued_E

Accounts Payable and Accrued Expenses	3 Months Ended
	Mar. 31, 2014
Accounts Payable and Accrued Expenses	'
Accounts Payable and Accrued Expenses	'
	6. Accounts Payable and Accrued Expenses
	Accounts payable and accrued expenses consist of the following at March 31, 2014 December 31, 2013:
		March 31,		December 31,
		2014		2013
	Accrued research and development costs	$	3,342,617	$	1,966,360
	Accrued compensation	1,317,996		2,043,704
	Accrued professional fees	252,289		372,267
	Short-term portion of deferred revenue	286,000		286,000
	Other accrued liabilities	274,170		345,477
	Total	$	5,473,072	$	5,013,808

Common_Stock

Common Stock	3 Months Ended
	Mar. 31, 2014
Common Stock	'
Common Stock	'
	7. Common Stock
	At the 2013 annual meeting of stockholders held on June 19, 2013, the stockholders voted in favor of an amendment to the Company’s Restated Certificate of Incorporation to increase the Company’s authorized share capital by 11,250,000 shares of common stock. As of December 31, 2013, the Company was authorized to issue 33,750,000 shares of common stock.
	Dividends on common stock will be paid when, and if, declared by the board of directors. Each holder of common stock is entitled to vote on all matters and is entitled to one vote for each share held. The Company will, at all times, reserve and keep available, out of its authorized but unissued shares of common stock, sufficient shares to effect the conversion of the shares of the stock options.
	In connection with the Company’s successful IPO in January 2013, the Company issued warrants to purchase up to 99,529 shares of the Company’s common stock to representatives of Aegis Capital Corp, the lead underwriter in the IPO. The warrants are exercisable for cash or on a cashless basis at a price per share equal to $15.00. The term of the warrants is four years and they expire on January 28, 2018.

Net_Loss_Income_Per_Common_Sha

Net (Loss) Income Per Common Share	3 Months Ended
	Mar. 31, 2014
Net (Loss) Income Per Common Share	'
Net (Loss) Income Per Common Share	'
	8. Net (Loss) Income Per Common Share
	The Company accounts for and discloses net income (loss) per share using the treasury stock method. Net income (loss) per common share, or basic income (loss) per share, is computed by dividing net income (loss) by the weighted-average number of common shares outstanding. Net income (loss) per common share assuming dilutions, or diluted income (loss) per share, is computed by reflecting the potential dilution from the exercise of in-the-money stock options, non-vested restricted stock and non-vested restricted stock units.
	The following table sets forth the computation of basic and diluted net loss per share for the periods indicated:
		Three Months Ended March 31,
		2014			2013
	Basic and diluted net loss per common share calculation:
	Net loss	$	(8,999,926	)	$	(5,505,646	)
	Basic and diluted weighted-average common shares	12,875,228			6,147,589
	Basic and diluted net loss per share	$	(0.70	)	$	(0.90	)
	The difference between basic and diluted weighted-average common shares generally results from the assumption that dilutive stock options outstanding were exercised, dilutive restricted stock has vested, outstanding warrants are issued and the conversion of convertible notes. For the three-month periods ended March 31, 2014 and 2013, the Company reported a loss from operations and therefore, all potentially dilutive stock options, restricted stock, outstanding warrants and convertible notes as of such date were excluded from the computation of diluted net loss per share as their effect would have been anti-dilutive. The total shares of stock options, restricted stock, outstanding warrants and convertible notes that could potentially dilute earnings per share in the future, but which were not included in the calculation of diluted net loss per share because their affect would have been anti-dilutive were as follows:
		Three Months Ended
		March 31
		2014		2013
	Restricted stock	336,494			19,910
	Options outstanding	1,545,097		1,881,339
	Warrants	99,529		99,529
	Convertible notes	—		233,967
	Total	1,981,120			2,234,745

Revenue

Revenue	3 Months Ended
	Mar. 31, 2014
Revenue	'
Revenue	'
	9. Revenue
	In October 2013, the Company entered into an award contract (the “Agreement”) with The Leukemia and Lymphoma Society (“LLS”). LLS is a national voluntary health agency which, among other activities, encourages and sponsors research relating to leukemia, lymphoma, Hodgkin’s disease and myeloma to develop therapies to cure or mitigate these diseases. To further its mission, LLS provides research funding to entities that can demonstrate after LLS’s review process that their proposed research projects have scientific promise to advance LLS’s effort to find treatments and cures for the above diseases and their complications. Pursuant to the Agreement LLS agreed to provide funding to the Company not to exceed $3.5 million to fund the Company’s development program related to the Company’s pre-clinical and clinical product development activities. The Company received $1.0 million in October 2013, upon execution of the Agreement and could receive the additional $2.5 million based on the completion of certain milestone events. The Company has recognized approximately $0.1 million of revenue related to the Leukemia and Lymphoma Society grant for the three-month period ended March 31, 2014, which reflects three months of revenue recognized on a straight line basis, based on the Company’s best estimates of work performed. The agreement terminates when there are no longer any payment obligations.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2014
Income Taxes	'
Income Taxes	'
	10.  Income Taxes
	The Company did not record an income tax provision or benefit for the three-month periods ended March 31, 2014 and 2013, respectively, due to the fact that the Company cannot benefit from its net operating losses. The Company has never had the ability to carry back losses to previous years to recover taxes paid and future utilization of these losses is uncertain.
	The Company files income tax returns in the United States and in the State of New York. The Company is not currently being audited by the Internal Revenue Service or any state taxing jurisdiction.
	Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and their basis for income tax purposes and the tax effects of net operating loss and tax credit carryforwards.
	Valuation allowances reduce deferred tax assets to the amounts that are more likely than not to be realized. As of March 31, 2014, the Company has recorded additional deferred tax assets which are fully offset by a valuation allowance. Realization of the deferred tax assets is dependent on generating sufficient taxable income in the future. At present, the likelihood of the Company being able to fully utilize its deferred income tax benefits against future income is uncertain.

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2014
Stock-Based Compensation	'
Stock-Based Compensation	'
	11.  Stock-Based Compensation
	The Company’s 2012 Stock Equity Incentive Plan (the “2012 Plan”), which was adopted by the board of directors and approved by the stockholders in July 2012, became effective immediately prior to the closing of the Company’s initial public offering. In addition, the Company’s 2004 Stock Option and Grant Plan (the “2004 Plan”) was terminated effective immediately prior to the closing of the Company’s initial public offering. The 1,819,839 options to purchase common stock and 34,506 restricted stock awards executed prior to the effective date of such termination remain in full force and effect pursuant to their terms and the terms of the 2004 Plan. The 2012 Plan initially authorized the Company to grant up to 1,663,727 shares of common stock to eligible employees, directors, and non-employee consultants and advisors to the Company in the form of options to purchase common stock of the Company at a price not less than the estimated fair value at the date of grant. Under the provisions of the 2012 Plan, no option will have a term in excess of 10 years.
	As of March 31, 2014, there were 1,322,795 shares of common stock available for future grants under the 2012 Plan.
	Total compensation cost that has been charged against operations related to the above plans was approximately $1.0 million and $2.3 million for the three-month periods ended March 31, 2014 and 2013, respectively. The Company does not recognize a tax benefit with respect to an excess stock compensation deduction until the deduction actually reduces the Company’s income tax liability. No income tax benefit was recognized in the statements of operations for share-based compensation arrangements for the three-month periods ended March 31, 2014 and 2013.
	The following table summarizes stock-based compensation related to the above plans by expense category for the three-month periods ended March 31, 2014 and 2013:
		Three Months Ended
		March 31,
		2014			2013
	Research and development	$	709,642		$	1,364,408
	General and administrative	332,925			920,779
	Total	$	1,042,567		$	2,285,187
	Stock Options
	The Company grants stock options to employees, Directors and non-employee consultants, with exercise prices equal to the closing price of the underlying shares of the Company’s common stock on the date that the options are granted. Options granted have a term of 10 years from the grant date. Options granted to employees generally vest over a four-year period and options granted to Directors vest in equal yearly installments over a three-year period from the date of grant. Options to Directors are granted on an annual basis and represent compensation for services performed by the board of directors. Compensation cost for stock options granted to employees and Directors is charged against operations using the straight-line attribution method between the grant date for the option and each vesting date. The Company estimates the fair value of stock options on the grant date by applying the Black-Scholes option pricing valuation model. The application of this valuation model involves assumptions that are highly subjective, judgmental and sensitive in the determination of compensation cost.
	The weighted-average key assumptions used in determining the fair value of options granted for the three months ended March 31, 2014 and 2013 are as follows:
		Three Months Ended
		March 31,
		2014		2013
	Weighted-average volatility	89.6	%	80.4	%
	Weighted-average risk-free interest rate	2	%	1	%
	Weighted-average expected term in years	6.25		6.25
	Dividend yield	0	%	0	%
	The Company’s computation of stock-price volatility is based on the volatility rates of comparable publicly held companies over a period equal to the estimated useful life of the options granted by the Company. The Company’s computation of expected life was determined using the “simplified” method which is the midpoint between the vesting date and the end of the contractual term. The Company believes that it does not have sufficient reliable exercise data in order to justify the use of a method other than the “simplified” method of estimating the expected exercise term of employee stock option grants. The Company has paid no dividends to stockholders. The risk-free interest rate is based on the zero-coupon U.S. Treasury yield at the date of grant for a term equivalent to the expected term of the option.
	For the three-month period ended March 31, 2014, the Company issued 9,035 shares of the Company’s common stock upon the exercise of outstanding stock options and received proceeds of $36,953. There were no exercises of stock options for the three-month period ended March 31, 2013. As of March 31, 2014, there was approximately $7.1 million of unrecognized compensation cost, adjusted for estimated forfeitures, related to unamortized stock option compensation which is expected to be recognized over a remaining weighted-average period of approximately 2.8 years. Total unrecognized compensation cost will be adjusted for future changes in estimated forfeitures.
	The following table summarizes the activity related to the Company’s stock options at March 31, 2014 and December 31, 2013:
		Options		Weighted-			Weighted-	Aggregate
				Average			Average	Intrinsic
				Exercise Price			Remaining	Value
							Contractual Life
	Outstanding at December 31, 2013	1,326,486		$	4.89
	Options granted	256,391		23.98
	Options exercised	(9,035	)	4.09
	Options forfeited	(28,745	)	4.86
	Outstanding at March 31, 2014	1,545,097		$	8.07		7.35	$	20,275,840
	Options exercisable at March 31, 2014	857,311		$	3.4		6.18	$	14,537,293
	The aggregate intrinsic value in the previous table reflects the total pretax intrinsic value (the difference between the Company’s closing stock price on the last trading day of the period and the exercise price of the options, multiplied by the number of in-the-money stock options) that would have been received by the option holders had all option holders exercised their options on March 31, 2014. The intrinsic value of the Company’s stock options changes based on the closing price of the Company’s common stock. The total intrinsic value of options exercised (the difference in the market price of the Company’s common stock on the exercise date and the price paid by the optionee to exercise the option) was approximately $0.1 million for the three-month period ended March 31, 2014. There were no exercises of stock options for the three-month period ended March 31, 2013.
	Restricted Stock
	The Company grants restricted stock to its employees and Directors. Restricted stock is recorded as deferred compensation and charged against earnings on a straight-line basis over the vesting period, which ranges from one to four years in duration. Restricted stock to Directors is granted on a yearly basis and represents compensation for services performed on the Company’s board of directors. Restricted stock awards to Directors vest in equal installments over a three-year period from the grant date. Compensation cost for restricted stock is based on the award’s grant date fair value, which is the closing market price of the Company’s common stock on the grant date, multiplied by the number of shares awarded.
	The following table summarizes the activity related to the Company’s restricted stock at March 31, 2014 and December 31, 2013:
		Number of Shares		Weighted-
				Average Grant
				Date Fair Value
				Per Share
	Outstanding at December 31, 2013	229,250		$	17.34
	Shares granted	112,666		24.14
	Shares vested	(4,645	)	5.97
	Shares forfeited	(777	)	25.05
	Outstanding at March 31, 2014	336,494		$	16.44
	For the three-month period ended March 31, 2014, the Company granted 112,666 shares of restricted stock, at a weighted-average grant date fair value of $24.14 per share amounting to approximately $2.7 million in total aggregate fair value. As of March 31, 2014, approximately 336,494 shares remained unvested and there was approximately $5.6 million of unrecognized compensation cost related to restricted stock which is expected to be recognized over a remaining weighted-average period of approximately 3.3 years. The total fair value of restricted stock vested during the three-month period ended March 31, 2014 was approximately $0.1 million. There was no vesting of restricted stock for the three-month period ended March 31, 2013.
	Awards Granted to Non-Employees
	The Company periodically re-measures the fair value of stock-based awards issued to non-employees and records expense over the requisite service period. Total compensation cost charged against operations related to options granted to non-employees was approximately $30,000 and $0.6 million for the three-month periods ended years ended March 31, 2014 and 2013, respectively.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies	'
Commitments and Contingencies	'
	12. Commitments and Contingencies
	The Company has entered into research and development agreements with third parties for the development of oncology products. These agreements require the Company to fund the development of such products and potentially make milestone payments and royalties on net sales in the future based on the Company’s successful development of the products. The timing and the amount of milestone payments in the future are not certain.
	Under the Company’s license agreements, the Company could be required to pay up to a total of $29.0 million upon achieving certain milestones, such as the initiation of clinical trials or the granting of patents. From Inception through December 31, 2013, the Company has paid or accrued $2.2 million in payments resulting from the execution of certain agreements, patent approvals, the initiation of sponsored research agreements, and compound development agreements. Milestone payments will also be due upon the issuance of certain patents, the initiation of certain clinical trials, the submission of regulatory applications and certain regulatory approvals, in addition to sales milestones and single-digit royalties payable on commercial sales, if any occur.
	Scott and White
	In June 2006, the Company entered into a research and license agreement, as amended in December 2008, March 2010 and July 2011 (collectively the “S&W Agreement”), with Scott and White Memorial Hospital and Scott, Sherwood and Brindley Foundation, and its affiliate Scott and White Clinic (collectively “S&W”) for the rights to SL-401 and SL-501. SL-401 is a clinical-stage targeted therapy directed to the interleukin-3 receptor, or IL-3R, and is being developed to treat patients with hematologic cancers. SL-501 is a next generation IL-3R-targeted therapy and is in preclinical development. The Company is required to pay customary single-digit royalties on sales, if any, of new products approved utilizing the licensed compounds, and a percentage of up-front payments the Company receives from a sublicensee. The S&W Agreement will expire in its entirety upon the later of (i) the 10th anniversary of the first commercial sale of a product, or (ii) the expiration of the last issued patent claiming or covering a product. The Company may terminate the S&W Agreement at its sole discretion at any time after a specified number of days following written notice and either party may terminate for a material breach of the agreement that is not cured within a specified number of days.
	University of Pittsburgh
	In September 2009, the Company entered into an exclusive license agreement with the University of Pittsburgh (“UP”) that covers patent rights claiming an analog peptide of IL-13Rα2, an active ingredient of SL-701. SL-701 is an enhanced immunotherapy being developed to treat patients with advanced brain cancer(the “UP Agreement”). The Company paid UP an upfront license fee that was expensed to research and development cost for the year ended December 31, 2009. In addition to the upfront payment, the Company will be required to pay annual fees, milestones (which are contingent upon achievement of pre-defined clinical, regulatory and commercial events), and, upon regulatory approval, single-digit royalties on net sales, and a percentage of non-royalty revenue from sublicensees, which decreases if the applicable sublicense agreement is entered into after a certain clinical milestone has been met. The UP Agreement will expire in its entirety upon the expiration of the last issued patent claiming or covering the product. The Company may terminate the UP Agreement at its sole discretion at any time after a specified number of days following written notice and UP may terminate for a material breach of the agreement by the Company that is not cured within a specified number of days.
	In March 2012, the Company entered into a non-exclusive license agreement with UP that covers patent rights claiming a peptide of EphA2, another active ingredient of SL-701, which the Company may use for the diagnosis, treatment or prevention of diseases and tumors of the brain. The Company paid UP an initial license fee and will be required to pay UP annual license maintenance fees until the first commercial sale of a licensed product, a customary single-digit royalty on sales, and a minimum annual royalty following the first commercial sale of a licensed product. The UP Agreement will expire in its entirety upon the expiration of the last issued patent claiming or covering the product. The Company may terminate the UP Agreement at its sole discretion at any time after a specified number of days following written notice and UP may terminate for a material breach of the agreement by the Company that is not cured within a specified number of days.
	In March 2012, the Company also entered into a non-exclusive license agreement with UP for the right to use certain information and data contained in the INDs for the clinical trials of SL-701 that were conducted by UP. The Company may use the information and data for the development, manufacture, regulatory approval and commercialization of pharmaceutical products, and UP has granted the Company a right of reference to such INDs for its planned SL-701 clinical trial of pediatric patients with glioma. The Company paid UP an initial license fee and will be required to make a payment following a specified regulatory milestone, and a percentage of non-royalty revenue received from any sublicensees. The UP Agreement will expire in its entirety in March 2032 unless earlier terminated by a party. The Company may terminate the UP Agreement at its sole discretion at any time prior to incorporating or referencing the data or UP INDs, after a specified number of days following written notice, and UP may terminate for a material breach of the agreement by the Company that is not cured within a specified number of days or if the IL-13Rα2 license agreement is terminated.
	Other Research and Development Agreements
	The Company has also licensed rights to certain technologies or intellectual property in the field of oncology. The Company is generally required to make upfront payments as well as other payments upon successful completion of preclinical, clinical, regulatory or sales milestones. In addition, these agreements generally require the Company to pay royalties on sales of the products arising from these agreements. These agreements generally permit the Company to terminate the agreement with no significant continuing obligation.
	As part of the agreements discussed above, the Company has committed to make potential future milestone payments to third parties as part of its licensing agreements. Payments generally become due and payable only upon the achievement of certain developmental, regulatory and/or commercial milestones. Because the achievement of these milestones is neither probable nor reasonably estimable, the Company has not recorded a liability on its balance sheet for any such contingencies.
	Compensation Arrangements
	Subsequent to the closing of the IPO, certain bonuses and salary increases in the amount of $1.0 million were paid upon approval of the board of directors and the satisfaction of certain contingencies, with an additional $0.4 million subject to the same contingencies and payable one year after the IPO.
	Contractual Agreements
	In February 2013, the Company entered into a bioprocessing services agreement with a vendor for approximately $2.9 million if all services are performed under the contract. As of December 31, 2013, approximately $2.1 million of the contract had been paid or accrued. The remaining services under this contract are expected to be performed during 2014.
	The Company has agreements in place with two contract research organizations (“CROs”) to facilitate research and clinical and data management services in connection with our two clinical-stage product candidates, SL-401 and SL-701. The Company’s total obligation under these contracts is expected to be approximately $12.5 million through 2016.
	Lease Agreement
	In July 2013, the Company entered into a leasing agreement with respect to its corporate offices at 750 Lexington Avenue, New York, New York, for a monthly rent of $50,625. The term of this lease agreement is 36 months.
	The Company’s future annual minimum lease payments for each of the following calendar years are as follows:
	Remainder of 2014	$	455,625
	2015	607,500
	2016	303,750
		$	1,366,875
	Rent expense charged to operations was approximately $0.2 million and $14,000 for the three-month periods ended March 31, 2014 and 2013, respectively. Rent expense is included in general and administrative expenses in the Company’s Statements of Operations.

Related_Party_Items

Related Party Items	3 Months Ended
	Mar. 31, 2014
Related Party Items	'
Related Party Items	'
	13. Related Party Items
	Receivable from Related Party
	In November 2013, the Company recorded a $0.2 million receivable from an executive of the Company related to New York State tax withholdings resulting from an exercise of expiring stock options. This item is reflected on the Company’s balance sheets as a related party receivable.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2014
Summary of Significant Accounting Policies	'
Recently Issued Accounting Pronouncements	'
	Recently Issued Accounting Pronouncements
	During the quarter ended March 31, 2014, there were no new accounting pronouncements or updates to recently issued accounting pronouncements disclosed in the 2013 Form 10-K, that significantly affect the Company’s present or future results of operations, overall financial condition, liquidity or disclosures.

Prepaid_expenses_and_other_cur1

Prepaid expenses and other current assets (Tables)	3 Months Ended
	Mar. 31, 2014
Prepaid expenses and other current assets	'
Schedule of prepaid expenses and other current assets	'
		March 31,		December 31,
		2014		2013
	Prepaid CRO costs	482,038		39,630
	Prepaid insurance	388,340		43,321
	Deposits	209,965		209,965
	Other prepaid expenses and advances	521,726		—
	Total	$	1,602,069	$	292,916

Furniture_and_Fixtures_Tables

Furniture and Fixtures (Tables)	3 Months Ended
	Mar. 31, 2014
Furniture and Fixtures	'
Schedule of furniture and fixtures	'
		March 31,			December 31,
		2014			2013
	Office furniture and fixtures	$	460,000		$	460,000
	Less accumulated depreciation	(115,000		)	(76,667		)
	Furniture and fixtures, net	$	345,000		$	383,333

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2014
Fair Value Measurements	'
Schedule of assets and liabilities measured at fair value on recurring basis	'
		March 31, 2014
		Quoted
		Prices in
		Active		Significant
		Markets for		Other		Significant			Balance
		Identical		Observable		Unobservable			at
		Assets		Inputs		Inputs			March 31,
		(Level 1)		(Level 2)		(Level 3)			2014
	Assets:
	Cash and cash equivalents	$	24,201,212	$	—	$	—		$	24,201,212
	Long-term investments	51,444,924		—		—			51,444,924
	Total assets at fair value	$	75,646,136	$	—	$	—		$	75,646,136
		December 31, 2013
		Quoted
		Prices in
		Active		Significant
		Markets for		Other		Significant			Balance
		Identical		Observable		Unobservable			at
		Assets		Inputs		Inputs			December 31,
		(Level 1)		(Level 2)		(Level 3)			2013
	Assets:
	Cash and cash equivalents	$	44,200,420	$	—	$	—		$	44,200,420
	Long-term investments	40,204,912		—		—			40,204,912
	Total assets at fair value	$	84,405,332	$	—	$	—		$	84,405,332
Summary of available-for-sale investments held by the Company	'
		March 31, 2014
				Gross		Gross			Estimated
		Amortized		Unrealized		Unrealized			Fair
		Cost		Gains		Losses			Value
	Cash equivalents:
	Money market funds	$	22,453,795	$	—	$	—		$	22,453,795
	Long-term investments:
	Fixed-income treasury portfolio:
	Federal home loan bank	17,781,152		1,664		(6,768		)	17,776,048
	Federal farm credit bank	13,876,085		8,656		(5,893		)	13,878,848
	Freddie Mac	14,821,350		3,200		(2,869		)	14,821,681
	Fannie Mae	4,966,346		2,021		(20		)	4,968,347
	Total Long-term investments	51,444,933		15,541		(15,550		)	51,444,924
	Total	$	73,898,728	$	15,541	$	(15,550	)	$	73,898,719
		December 31, 2013
				Gross		Gross			Estimated
		Amortized		Unrealized		Unrealized			Fair
		Cost		Gains		Losses			Value
	Cash equivalents:
	Money market funds	$	41,441,975	$	—	$	—		$	41,441,975
	Long-term investments:
	Fixed-income treasury portfolio:
	Federal home loan bank	13,789,246		—		(14,752		)	13,774,494
	Federal farm credit bank	11,476,874		—		(13,701		)	11,463,173
	Freddie Mac	10,020,626		—		(8,340		)	10,012,286
	Fannie Mae	4,961,941		—		(6,982		)	4,954,959
	Total Long-term investments	40,248,687		—		(43,775		)	40,204,912
	Total	$	81,690,662	$	—	$	(43,775	)	$	81,646,887

Accounts_Payable_and_Accrued_E1

Accounts Payable and Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2014
Accounts Payable and Accrued Expenses	'
Schedule of components of accounts payable and accrued expenses	'
		March 31,		December 31,
		2014		2013
	Accrued research and development costs	$	3,342,617	$	1,966,360
	Accrued compensation	1,317,996		2,043,704
	Accrued professional fees	252,289		372,267
	Short-term portion of deferred revenue	286,000		286,000
	Other accrued liabilities	274,170		345,477
	Total	$	5,473,072	$	5,013,808

Net_Loss_Income_Per_Common_Sha1

Net (Loss) Income Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2014
Net (Loss) Income Per Common Share	'
Schedule of computation of basic and diluted net loss per share	'
		Three Months Ended March 31,
		2014			2013
	Basic and diluted net loss per common share calculation:
	Net loss	$	(8,999,926	)	$	(5,505,646	)
	Basic and diluted weighted-average common shares	12,875,228			6,147,589
	Basic and diluted net loss per share	$	(0.70	)	$	(0.90	)
Schedule of total shares of stock options, restricted stock, outstanding warrants and convertible notes that could potentially dilute earnings per share in the future, but which were not included in the calculation of diluted net loss per share because their affect would have been anti-dilutive	'
		Three Months Ended
		March 31
		2014		2013
	Restricted stock	336,494			19,910
	Options outstanding	1,545,097		1,881,339
	Warrants	99,529		99,529
	Convertible notes	—		233,967
	Total	1,981,120			2,234,745

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2014
Stock-Based Compensation	'
Schedule of stock-based compensation by expense category	'
		Three Months Ended
		March 31,
		2014			2013
	Research and development	$	709,642		$	1,364,408
	General and administrative	332,925			920,779
	Total	$	1,042,567		$	2,285,187
Schedule of weighted-average key assumptions used in determining the fair value of options	'
		Three Months Ended
		March 31,
		2014		2013
	Weighted-average volatility	89.6	%	80.4	%
	Weighted-average risk-free interest rate	2	%	1	%
	Weighted-average expected term in years	6.25		6.25
	Dividend yield	0	%	0	%
Summary of activity related to the Company's stock options	'
		Options		Weighted-			Weighted-	Aggregate
				Average			Average	Intrinsic
				Exercise Price			Remaining	Value
							Contractual Life
	Outstanding at December 31, 2013	1,326,486		$	4.89
	Options granted	256,391		23.98
	Options exercised	(9,035	)	4.09
	Options forfeited	(28,745	)	4.86
	Outstanding at March 31, 2014	1,545,097		$	8.07		7.35	$	20,275,840
	Options exercisable at March 31, 2014	857,311		$	3.4		6.18	$	14,537,293
Summary of activity related to the Company's restricted stock	'
		Number of Shares		Weighted-
				Average Grant
				Date Fair Value
				Per Share
	Outstanding at December 31, 2013	229,250		$	17.34
	Shares granted	112,666		24.14
	Shares vested	(4,645	)	5.97
	Shares forfeited	(777	)	25.05
	Outstanding at March 31, 2014	336,494		$	16.44

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies	'
Schedule of future minimum lease payments	'
	Remainder of 2014	$	455,625
	2015	607,500
	2016	303,750
		$	1,366,875

Organization_and_Basis_of_Pres1

Organization and Basis of Presentation (Details)	3 Months Ended
	Mar. 31, 2014
	item
Organization and Basis of Presentation	'
Number of clinical stage programs	2
Minimum term for which anticipated operating cash requirements are funded	'2 years

Prepaid_expenses_and_other_cur2

Prepaid expenses and other current assets (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Prepaid expenses and other current assets	'	'
Prepaid CRO costs	$482,038	$39,630
Prepaid insurance	388,340	43,321
Deposits	209,965	209,965
Other prepaid expenses and advances	521,726	'
Total	$1,602,069	$292,916

Furniture_and_Fixtures_Details

Furniture and Fixtures (Details) (USD $)	3 Months Ended		128 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Dec. 31, 2013
Furniture and fixtures	'	'	'	'
Less accumulated depreciation	($115,000)	'	($115,000)	($76,667)
Furniture and fixtures, net	345,000	'	345,000	383,333
Depreciation expense	38,333	0	115,000	'
Office furniture and fixtures	'	'	'	'
Furniture and fixtures	'	'	'	'
Office furniture and fixtures, Gross	$460,000	'	$460,000	$460,000

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Fair Value Measurements	'	'
Transfers of assets between Level 1 to Level 2	$0	'
Transfers of assets between Level 2 to Level 1	0	'
Transfers of liabilities between Level 1 to Level 2	0	'
Transfers of liabilities between Level 2 to Level 1	0	'
Assets:	'	'
Long-term investments	51,444,924	40,204,912
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)	'	'
Assets:	'	'
Cash and cash equivalents	24,201,212	44,200,420
Long-term investments	51,444,924	40,204,912
Total assets at fair value	75,646,136	84,405,332
Recurring basis | Balance	'	'
Assets:	'	'
Cash and cash equivalents	24,201,212	44,200,420
Long-term investments	51,444,924	40,204,912
Total assets at fair value	$75,646,136	$84,405,332

Fair_Value_Measurements_Detail1

Fair Value Measurements (Details 2) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Available-for-sale investments	'	'
Total Gross Unrealized Gains	$15,541	'
Total Gross Unrealized Losses	-15,550	-43,775
Long-term investments	'	'
Available-for-sale investments	'	'
Amortized Cost	51,444,933	40,248,687
Gross Unrealized Gains	15,541	'
Gross Unrealized Losses	-15,550	-43,775
Estimated Fair Value	51,444,924	40,204,912
Long-term investments | Maximum	'	'
Available-for-sale investments	'	'
Remaining contractual maturity	'2 years	'
Long-term investments | Federal home loan bank	'	'
Available-for-sale investments	'	'
Amortized Cost	17,781,152	13,789,246
Gross Unrealized Gains	1,664	'
Gross Unrealized Losses	-6,768	-14,752
Estimated Fair Value	17,776,048	13,774,494
Long-term investments | Federal farm credit bank	'	'
Available-for-sale investments	'	'
Amortized Cost	13,876,085	11,476,874
Gross Unrealized Gains	8,656	'
Gross Unrealized Losses	-5,893	-13,701
Estimated Fair Value	13,878,848	11,463,173
Long-term investments | Freddie Mac	'	'
Available-for-sale investments	'	'
Amortized Cost	14,821,350	10,020,626
Gross Unrealized Gains	3,200	'
Gross Unrealized Losses	-2,869	-8,340
Estimated Fair Value	14,821,681	10,012,286
Long-term investments | Fannie Mae	'	'
Available-for-sale investments	'	'
Amortized Cost	4,966,346	4,961,941
Gross Unrealized Gains	2,021	'
Gross Unrealized Losses	-20	-6,982
Estimated Fair Value	4,968,347	4,954,959
Short-term investments | Maximum	'	'
Available-for-sale investments	'	'
Remaining contractual maturity	'12 months	'
Estimated Fair Value	'	'
Available-for-sale investments	'	'
Total	73,898,719	81,646,887
Amortized Cost	'	'
Available-for-sale investments	'	'
Total	73,898,728	81,690,662
Money market funds | Amortized Cost	'	'
Available-for-sale investments	'	'
Cash equivalents	22,453,795	41,441,975
Money market funds | Estimated Fair Value	'	'
Available-for-sale investments	'	'
Cash equivalents	$22,453,795	$41,441,975

Fair_Value_Measurements_Detail2

Fair Value Measurements (Details 3) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
			Unrealized gains or losses on Investments	Unrealized gains or losses on Investments
			Amount reclassified from accumulated other comprehensive income	Amount reclassified from accumulated other comprehensive income
Available-for-sale investments	'	'	'	'
Other income (expense)	'	'	$0	$0
Available-for-sale securities in a continuous unrealized loss position for greater than twelve months	$0	$0	'	'

Accounts_Payable_and_Accrued_E2

Accounts Payable and Accrued Expenses (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Accrued Liabilities	'	'
Accrued research and development costs	$3,342,617	$1,966,360
Accrued compensation	1,317,996	2,043,704
Accrued professional fees	252,289	372,267
Short-term portion of deferred revenue	286,000	286,000
Other accrued liabilities	274,170	345,477
Total	$5,473,072	$5,013,808

Common_Stock_Details

Common Stock (Details) (USD $)	0 Months Ended		3 Months Ended
	Jun. 19, 2013	Jan. 31, 2013	Mar. 31, 2014	Dec. 31, 2013
			item
Common Stock	'	'	'	'
Additional shares of common stock authorized	11,250,000	'	'	'
Number of shares of common stock authorized to be issued	'	'	33,750,000	33,750,000
Number of votes to which holders of common shares are entitled for each share held	'	'	1	'
Number of shares of common stock that may be purchased by warrants	'	99,529	'	'
Exercisable price of warrants (in dollars per share)	'	$15	'	'
Term of warrants	'	'4 years	'	'

Net_Loss_Income_Per_Common_Sha2

Net (Loss) Income Per Common Share (Details) (USD $)	3 Months Ended		128 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014
Basic and diluted net loss per common share calculation:	'	'	'
Net loss	($8,999,926)	($5,505,646)	($42,956,855)
Basic and diluted weighted-average common shares	12,875,228	6,147,589	'
Basic and diluted net loss per share (in dollars per share)	($0.70)	($0.90)	'

Net_Loss_Income_Per_Common_Sha3

Net (Loss) Income Per Common Share (Details 2)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Net (Loss) Income Per Common Share	'	'
Potentially dilutive securities excluded from the computation of earnings per share (in shares)	1,981,120	2,234,745
Restricted stock	'	'
Net (Loss) Income Per Common Share	'	'
Potentially dilutive securities excluded from the computation of earnings per share (in shares)	336,494	19,910
Options outstanding	'	'
Net (Loss) Income Per Common Share	'	'
Potentially dilutive securities excluded from the computation of earnings per share (in shares)	1,545,097	1,881,339
Warrants	'	'
Net (Loss) Income Per Common Share	'	'
Potentially dilutive securities excluded from the computation of earnings per share (in shares)	99,529	99,529
Convertible notes	'	'
Net (Loss) Income Per Common Share	'	'
Potentially dilutive securities excluded from the computation of earnings per share (in shares)	'	233,967

Revenue_Details

Revenue (Details) (USD $)	1 Months Ended	3 Months Ended	128 Months Ended
	Oct. 31, 2013	Mar. 31, 2014	Mar. 31, 2014
Revenue	'	'	'
Maximum amount of grants to be received from the Leukemia and Lymphoma Society	$3,500,000	'	'
Grant revenue	1,000,000	71,000	142,000
Amount of grants to be received upon completion of certain milestone	$2,500,000	'	'

StockBased_Compensation_Detail

Stock-Based Compensation (Details) (USD $)	3 Months Ended								3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Dec. 31, 2013	Jan. 31, 2013	Jan. 31, 2013	Mar. 31, 2014
			Options	Options	Restricted stock	Restricted stock	2004 Plan	2004 Plan	2012 Plan
							Options	Restricted stock
Stock Option Plan	'	'	'	'	'	'	'	'	'
Number of options to purchase common stock outstanding (in shares)	'	'	1,545,097	1,326,486	'	'	1,819,839	'	'
Number of restricted stock awards outstanding (in shares)	'	'	'	'	336,494	229,250	'	34,506	'
Number of common stock shares initially authorized for grant	'	'	'	'	'	'	'	'	1,663,727
Term of option	'	'	'10 years	'	'	'	'	'	'10 years
Shares available for future grants	'	'	'	'	'	'	'	'	1,322,795
Stock-based compensation expense	$1,042,567	$2,285,187	'	'	'	'	'	'	'
Tax benefits related to the stock-based compensation costs recognized	$0	$0	'	'	'	'	'	'	'

StockBased_Compensation_Detail1

Stock-Based Compensation (Details 2) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Stock-Based Compensation	'	'
Stock-based compensation expense	$1,042,567	$2,285,187
Research and development	'	'
Stock-Based Compensation	'	'
Stock-based compensation expense	709,642	1,364,408
General and administrative	'	'
Stock-Based Compensation	'	'
Stock-based compensation expense	$332,925	$920,779

StockBased_Compensation_Detail2

Stock-Based Compensation (Details 3) (USD $)	3 Months Ended	128 Months Ended	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2014
			Options	Options	Options	Options
					Employees	Directors
Stock-Based Compensation	'	'	'	'	'	'
Term of option	'	'	'10 years	'	'	'
Vesting period	'	'	'	'	'4 years	'3 years
Weighted average assumptions used to estimate the weighted average fair value of the options granted on the date of grant using the Black-Scholes option-pricing model	'	'	'	'	'	'
Weighted-average volatility (as a percent)	'	'	89.60%	80.40%	'	'
Weighted-average risk-free interest rate (as a percent)	'	'	2.00%	1.00%	'	'
Weighted-average expected term in years	'	'	'6 years 3 months	'6 years 3 months	'	'
Dividend yield (as a percent)	'	'	0.00%	0.00%	'	'
Dividends paid to stockholders	'	'	$0	'	'	'
Proceeds from exercise of stock options	36,953	1,330,703	36,953	'	'	'
Unrecognized compensation expense related to unvested stock options	'	'	7,100,000	'	'	'
Weighted average period over which unrecognized compensation expense is expected to be recognized	'	'	'2 years 9 months 18 days	'	'	'
Options	'	'	'	'	'	'
Outstanding balance at the beginning of the period (in shares)	'	'	1,326,486	'	'	'
Options granted (in shares)	'	'	256,391	'	'	'
Options exercised (in shares)	'	'	-9,035	0	'	'
Options forfeited (in shares)	'	'	-28,745	'	'	'
Outstanding balance at the end of the period (in shares)	'	'	1,545,097	'	'	'
Options exercisable (in shares)	'	'	857,311	'	'	'
Weighted Average Exercise Price	'	'	'	'	'	'
Outstanding balance at the beginning of the period (in dollars per share)	'	'	$4.89	'	'	'
Options granted (in dollars per share)	'	'	$23.98	'	'	'
Options exercised (in dollars per share)	'	'	$4.09	'	'	'
Options forfeited (in dollars per share)	'	'	$4.86	'	'	'
Outstanding balance at the end of the period (in dollars per share)	'	'	$8.07	'	'	'
Options exercisable (in dollars per share)	'	'	$3.40	'	'	'
Weighted-Average Remaining Contractual Life	'	'	'	'	'	'
Outstanding balance at the end of the period	'	'	'7 years 4 months 6 days	'	'	'
Options exercisable	'	'	'6 years 2 months 5 days	'	'	'
Aggregate Intrinsic Value	'	'	'	'	'	'
Outstanding balance at the end of the period (in dollars)	'	'	20,275,840	'	'	'
Options exercisable (in dollars)	'	'	14,537,293	'	'	'
Total intrinsic value of options exercised	'	'	$100,000	'	'	'

StockBased_Compensation_Detail3

Stock-Based Compensation (Details 4) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Awards Granted to Non-Employees	'	'
Stock-based compensation expense	$1,042,567	$2,285,187
Non-employees	'	'
Awards Granted to Non-Employees	'	'
Stock-based compensation expense	30,000	600,000
Restricted stock	'	'
Number of Shares	'	'
Outstanding balance at the beginning of the period (in shares)	229,250	'
Shares granted	112,666	'
Shares vested	-4,645	0
Shares forfeited	-777	'
Outstanding balance at the end of the period (in shares)	336,494	'
Weighted Average Grant Date Fair Value Per Share	'	'
Outstanding balance at the beginning of the period (in dollars per share)	$17.34	'
Shares granted (in dollars per share)	$24.14	'
Shares vested (in dollars per share)	$5.97	'
Shares forfeited (in dollars per share)	$25.05	'
Outstanding balance at the end of the period (in dollars per share)	$16.44	'
Total aggregate fair value of stock granted	2,700,000	'
Unrecognized compensation expense related to unvested restricted stock	5,600,000	'
Remaining weighted-average period for recognizing unrecognized compensation cost	'3 years 3 months 18 days	'
Total fair value of restricted stock vested	$100,000	'
Restricted stock | Directors	'	'
Stock-Based Compensation	'	'
Vesting period	'3 years	'
Restricted stock | Minimum	'	'
Stock-Based Compensation	'	'
Vesting period	'1 year	'
Restricted stock | Maximum	'	'
Stock-Based Compensation	'	'
Vesting period	'4 years	'

Commitments_and_Contingencies_1

Commitments and Contingencies (Details) (USD $)	0 Months Ended	1 Months Ended	3 Months Ended				3 Months Ended			3 Months Ended
	Jan. 31, 2013	Jul. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Dec. 31, 2013	Feb. 28, 2013	Mar. 31, 2014
					Research and development agreements with third parties	Research and development agreements with third parties	S&W Agreement	Bioprocessing services agreement	Bioprocessing services agreement	Contract research organizations agreement
										item
Commitments and contingencies	'	'	'	'	'	'	'	'	'	'
Amount required to be paid upon achievement of certain milestones	'	'	'	'	$29,000,000	'	'	'	'	'
Amount paid or accrued	'	'	'	'	'	2,200,000	'	2,100,000	'	'
Expiration term	'	'	'	'	'	'	'10 years	'	'	'
Contractual Agreement	'	'	'	'	'	'	'	'	'	'
Contractual agreement value	'	'	'	'	'	'	'	'	2,900,000	12,500,000
Amount paid or accrued	'	'	'	'	'	2,200,000	'	2,100,000	'	'
Number of contracts research organizations	'	'	'	'	'	'	'	'	'	2
Number of clinical-stage product candidates	'	'	'	'	'	'	'	'	'	2
Compensation Arrangements	'	'	'	'	'	'	'	'	'	'
Bonuses and salary increases paid upon the closing of the IPO	1,000,000	'	'	'	'	'	'	'	'	'
Bonuses and salary increases payable upon the closing of the IPO	400,000	'	'	'	'	'	'	'	'	'
Period after IPO after which increased bonus and salary is paid	'1 year	'	'	'	'	'	'	'	'	'
Monthly lease rent	'	50,625	'	'	'	'	'	'	'	'
Lease agreement term	'	'36 months	'	'	'	'	'	'	'	'
Future minimum lease payments	'	'	'	'	'	'	'	'	'	'
Remainder of 2014	'	'	455,625	'	'	'	'	'	'	'
2015	'	'	607,500	'	'	'	'	'	'	'
2016	'	'	303,750	'	'	'	'	'	'	'
Total	'	'	1,366,875	'	'	'	'	'	'	'
Rent expense	'	'	$200,000	$14,000	'	'	'	'	'	'

Related_Party_Items_Details

Related Party Items (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Nov. 30, 2013
			Executive
Related Party Transactions	'	'	'
Receivable from related party	$199,615	$199,615	$200,000