Stemline Therapeutics (STML) 10-K 16 Mar 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Mar. 12, 2015	Jun. 30, 2014
Document and Entity Information
Entity Registrant Name	STEMLINE THERAPEUTICS INC
Entity Central Index Key	1264587
Document Type	10-K
Document Period End Date	31-Dec-14
Amendment Flag	FALSE
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$162,410,910
Entity Common Stock, Shares Outstanding		17,819,923
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY

Balance_Sheets

Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$25,007,217	$44,200,420
Short-term investments	28,976,147
Related party receivable		199,615
Prepaid expenses and other current assets	1,636,808	292,916
Total current assets	55,620,172	44,692,951
Furniture and fixtures, net	230,000	383,333
Long-term investments	4,644,820	40,204,912
Total assets	60,494,992	85,281,196
Current liabilities:
Accounts payable and accrued expenses	4,473,842	5,013,808
Total current liabilities	4,473,842	5,013,808
Deferred grant revenue	607,999	643,000
Total liabilities	5,081,841	5,656,808
Stockholders' equity:
Preferred stock $0.0001 par value, 5,000,000 shares authorized, none issued and outstanding at December 31, 2014 and 2013
Common stock $0.0001 par value, 33,750,000 shares authorized at December 31, 2014 and 2013. 13,285,232 shares issued and outstanding at December 31, 2014 and 13,114,306 shares issued and outstanding at December 31, 2013	1,329	1,310
Additional paid-in capital	115,604,563	111,032,619
Accumulated other comprehensive income (loss)	3,000	-43,775
Accumulated deficit	-60,195,741	-31,365,766
Total stockholders' equity (deficit)	55,413,151	79,624,388
Total liabilities and stockholders' equity (deficit)	$60,494,992	$85,281,196

Balance_Sheets_Parenthetical

Balance Sheets (Parenthetical) (USD $)	Dec. 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	13,285,232	13,114,306
Common stock, shares outstanding	13,285,232	13,114,306

Statement_of_Operations

Statement of Operations (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues:
Grant revenue	$335,287	$71,000
Operating expenses:
Research and development	21,240,599	16,178,744	3,376,962
General and administrative	8,084,580	7,871,719	3,090,611
Total operating expenses	29,325,179	24,050,463	6,467,573
Loss from operations	-28,989,892	-23,979,463	-6,467,573
Other income	3,607	280,687	301,684
Other expense			-35
Interest expense		-516,871	-118,765
Interest income	156,310	19,136	9,907
Net loss	($28,829,975)	($24,196,511)	($6,274,782)
Net loss per common share:
Basic and Diluted (in dollars per share)	($2.23)	($2.35)	($1.82)
Weighted-average shares outstanding:
Basic and Diluted (in shares)	12,936,741	10,317,351	3,441,995

Statements_of_Comprehensive_Lo

Statements of Comprehensive Loss (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statements of Comprehensive Loss
Net loss	($28,829,975)	($24,196,511)	($6,274,782)
Other comprehensive loss:
Unrealized gain (loss) on investments	50,287	-43,775
Reclassification adjustment for gain on investments included in net loss	-3,512
Other comprehensive gain (loss)	46,775	-43,775
Comprehensive loss	($28,783,200)	($24,240,286)	($6,274,782)

Statements_of_Stockholders_Equ

Statements of Stockholders' Equity (Deficit) (USD $)	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Earnings (Deficit)	Total
Balance at Dec. 31, 2011	$344	$4,099,469		($894,473)	$3,205,340
Balance (in shares) at Dec. 31, 2011	3,441,995
Increase (Decrease) in Stockholders' Equity
Restricted stock grants	3	-3
Restricted stock grants (in shares)	34,506
Stock-based compensation		561,022			561,022
Net loss				-6,274,782	-6,274,782
Balance at Dec. 31, 2012	347	4,660,488		-7,169,255	-2,508,420
Balance (in shares) at Dec. 31, 2012	3,476,501
Increase (Decrease) in Stockholders' Equity
Issuance of common stock for cash in connection with initial and secondary public offerings, net of issuance costs	857	97,707,649			97,708,506
Issuance of common stock for cash in connection with initial and secondary public offerings, net of issuance costs (in shares)	8,573,911
Restricted stock grants	30	-30
Restricted stock grants (in shares)	304,528
Forfeiture of restricted stock grants	-4	4
Forfeiture of restricted stock grants (in shares)	-43,982
Stock-based compensation		4,847,086			4,847,086
Issuance of common stock in connection with the exercise of stock options	56	1,293,694			1,293,750
Issuance of common stock in connection with the exercise of stock options (in shares)	550,801
Issuance of common stock in connection with the conversion of convertible notes	24	2,101,080			2,101,104
Issuance of common stock in connection with the conversion of convertible notes (in shares)	252,547
Beneficial conversion related to interest expense		422,648			422,648
Net loss				-24,196,511	-24,196,511
Change in unrealized gain (loss) on available for sale securities			-43,775		-43,775
Balance at Dec. 31, 2013	1,310	111,032,619	-43,775	-31,365,766	79,624,388
Balance (in shares) at Dec. 31, 2013	13,114,306
Increase (Decrease) in Stockholders' Equity
Restricted stock grants	16	-16
Restricted stock grants (in shares)	138,663
Forfeiture of restricted stock grants	0	0
Forfeiture of restricted stock grants (in shares)	-777
Stock-based compensation		4,436,689			4,436,689
Issuance of common stock in connection with the exercise of stock options	3	135,271			135,274
Issuance of common stock in connection with the exercise of stock options (in shares)	33,040
Net loss				-28,829,975	-28,829,975
Change in unrealized gain (loss) on available for sale securities			46,775		46,775
Balance at Dec. 31, 2014	$1,329	$115,604,563	$3,000	($60,195,741)	$55,413,151
Balance (in shares) at Dec. 31, 2014	13,285,232

Statements_of_Cash_Flows

Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities
Net loss	($28,829,975)	($24,196,511)	($6,274,782)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	153,333	76,667
Stock-based compensation expense	4,436,689	4,847,086	561,022
Amortization of premium paid on marketable securities	249,264
Net gain on sale of marketable securities	-3,512
Non-cash interest expense		94,223	118,765
Mark-to-market of put option liability		-30,415	-68,815
Beneficial conversion of convertible interest		422,648
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	-1,343,892	6,173	-75,879
Related party receivable	199,615	-199,615
Accounts payable and accrued expenses	-539,966	2,218,257	1,613,141
Deferred grant revenue	-35,001	643,000
Net cash used in operating activities	-25,713,445	-16,118,487	-4,126,548
Cash flows from investing activities
Purchase of furniture and fixtures		-460,000
Purchase of marketable securities	-16,246,878	-40,248,687
Sale and maturities of marketable securities	22,631,846
Net cash used in investing activities	6,384,968	-40,708,687
Cash flows from financing activities
Proceeds from issuance of common stock, net		97,708,506
Proceeds from exercise of stock options	135,274	1,293,750
Proceeds from issuance of convertible notes			322,000
Net cash provided by financing activities	135,274	99,002,256	322,000
Net increase (decrease) in cash and cash equivalents	-19,193,203	42,175,082	-3,804,548
Cash and cash equivalents at beginning of period	44,200,420	2,025,338	5,829,886
Cash and cash equivalents at end of period	$25,007,217	$44,200,420	$2,025,338

Organization_and_Basis_of_Pres

Organization and Basis of Presentation	12 Months Ended
	Dec. 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, expanding and strengthening its intellectual property portfolio, developing its proprietary drug discovery platform, identifying and acquiring additional product and technology rights and raising capital. The Company was incorporated in Delaware on August 8, 2003 and has its principal office in New York, New York.
	Stemline Therapeutics, Inc. has incurred losses from operations since inception of $72.4 million. Since its inception, most of its resources have been dedicated to the discovery, acquisition and preclinical and clinical development of its product candidates.  In particular, it has expended and will continue to expend substantial resources for the foreseeable future developing its clinical candidates, SL-401 and SL-701, as well as its preclinical product candidates and drug discovery and acquisition efforts.  These expenditures will include costs associated with general and administrative costs, facilities costs, research and development, acquiring new technologies, manufacturing product candidates, conducting preclinical experiments and clinical trials and obtaining regulatory approvals, as well as commercializing any products approved for sale.  The Company anticipates incurring additional losses until such time, if ever, that it can generate significant sales of its products currently in development.  The Company expects its research and development expenses to increase significantly in connection with its ongoing and planned clinical trials.  As a result, the Company expects to continue to incur significant and increasing operating losses for the foreseeable future.
	Initial Public Offering
	On January 31, 2013, the Company completed its initial public offering (the “IPO”), selling 3,317,644 shares at an offering price of $10.00 per share. On January 29, 2013, the underwriters exercised in full their over-allotment option to purchase an additional 497,647 shares at an offering price of $10.00 per share. Aggregate gross proceeds from the IPO, including the exercise of the over-allotment option, were $38.2 million and net proceeds received after underwriting fees and offering expenses were approximately $32.3 million. Additionally, upon the closing of the IPO, certain transactions were triggered based on a successful completion of an IPO.  Convertible debt of $1.4 million principal, plus accrued interest thereon, was converted into 166,769 shares of common stock. The Company recorded approximately $1.5 million of compensation expense related to certain bonuses and salary increases payable upon continued employment and the occurrence of a specified financing, including the consummation of an initial public offering. Finally, the Company recorded one-time compensation expense of approximately $1.4 million for certain options and restricted stock that fully vested upon the closing of the IPO.
	Secondary Public Offerings
	On May 16, 2013, the Company completed a follow-on public offering (the “Secondary Offering”), selling 4,137,931 shares at an offering price of $14.50 per share. On May 22, 2013, the underwriters exercised in full their over-allotment option to purchase an additional 620,689 shares at an offering price of $14.50 per share. Aggregate gross proceeds from the Secondary Offering, including the exercise of the over-allotment option, were $69.0 million, and net proceeds received after underwriting fees and offering expenses were approximately $64.5 million.
	The Company may seek additional capital through a combination of private and public equity offerings, debt financings and collaborations and strategic and licensing arrangements.
	If adequate funds are not available to the Company on a timely basis, or at all, the Company may be required to terminate or delay clinical trials or other development activities for SL-401 or SL-701, or for one or more indications for which it is developing SL-401 and SL-701, or delay its establishment of sales and marketing capabilities or other activities that may be necessary to commercialize SL-401 or SL-701, if the Company obtains marketing approval.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies
	2. Summary of Significant Accounting Policies
	Use of Estimates
	The preparation of financial statements in conformity with generally accepted accounting principles in the US (US GAAP) requires management to make estimates and assumptions that affect the reported financial position at the date of the financial statements and the reported results of operations during the reporting period.  Such estimates and assumptions affect the reported amounts of assets, liabilities, revenues and expenses and disclosure of contingent assets and liabilities in the financial statements and accompanying notes.  Actual results could differ from those estimates.
	Cash Equivalents
	Cash equivalents consist of highly liquid instruments purchased with an original maturity of three months or less. At December 31, 2014 and 2013, cash equivalents consist of deposits in financial institutions. The Company maintains its cash deposits and cash equivalents with well-known and stable financial institutions.
	Concentration of Credit Risk
	Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash equivalents. The Company invests its excess cash in major U.S. banks and financial institutions, and its deposits, at times, exceed federally insured limits. The Company has not experienced any losses from credit risks.
	Investments
	The Company’s investments are considered to be available-for-sale and are carried at fair value. Unrealized gains and losses, if any, are reported as a separate component of stockholders’ equity (deficit) and are not reflected in the statements of operations until a sale transaction occurs or when declines in fair value are deemed to be other-than-temporary (“OTT”). The cost of investments classified as available-for-sale are adjusted for the amortization of premiums and accretion of discounts to maturity and recorded in other expense and other income, respectively. Realized gains and losses, if any, are determined using the specific identification method and are included in other income and other expense, respectively. Investments with original maturities beyond 90 days at the date of purchase and which mature at, or less than twelve months from, the balance sheet date are classified as current. Investments with a maturity beyond twelve months from the balance sheet date are classified as long-term.
	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 liabilities. Cash and cash equivalents, and long-term investments are carried at fair value (see Note 6). Financial instruments including other current assets, accounts payable and accrued liabilities are carried at cost, which approximate fair value given their short-term nature.
	Other-Than-Temporary Impairment Losses on Investments
	The Company regularly monitors its available-for-sale portfolio to evaluate the necessity of recording impairment losses for OTT declines in the fair value of investments. Management makes this determination through the consideration of various factors such as management’s intent and ability to retain an investment for a period of time sufficient to allow for any anticipated recovery in market value. OTT impairment losses result in a permanent reduction of the cost basis of an investment. For the years ended December 31, 2014 and 2013 the Company did not realize any investment losses due to OTT declines in fair value.
	Furniture and Fixtures
	Furniture and fixtures are stated at cost, less accumulated depreciation. Depreciation is provided over the estimated useful lives of the respective assets, which is three years, using the straight-line method.
	Impairment of Long-Lived Assets
	The Company reviews long-lived assets, (the Company’s furniture and fixtures), for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. The impairment loss, if recognized, would be based on the excess of the carrying value of the impaired asset over its respective fair value. The Company purchased fixed assets during 2013. For the years ended December 31, 2014 and 2013 the Company did not realize any impairment losses.
	Grant Revenue Recognition
	The Company has not yet generated any revenue from product sales. The Company’s sole source of revenue is grant revenue related to a $1.0 million research grant received from the Leukemia and Lymphoma Society in October 2013 and an additional $0.5 million that was received during the fourth quarter of 2014 based upon an additional milestone achieved.  This research grant was awarded to the Company to support funding some of the costs for the upcoming SL-401 clinical trials.  Grant payments received prior to the Company’s performance of work required by the terms of the research grant are recorded as deferred revenue and recognized as grant revenue once work is performed and qualifying costs are incurred. The Company has recognized approximately $0.3 million and $0.1 million of revenue related to the Leukemia and Lymphoma Society grant for the years ended December 31, 2014 and 2013, respectively, which reflect twelve months and three months of revenue recognized, respectively, on a straight line basis, based on the Company’s best estimates of the timing of work to be performed and qualifying costs incurred.
	Accrued Clinical Development Costs
	Outside research costs are a component of research and development expense. These expenses include fees paid to contract research organizations and other service providers that conduct certain clinical and product development activities on behalf of the Company. Depending upon the timing of payments to the service providers, the Company recognizes prepaid expenses or accrued expenses related to these costs. These accrued or prepaid expenses are based on management’s estimates of the work performed under service agreements, milestones achieved and experience with similar contracts. The Company monitors each of these factors and adjusts estimates accordingly.
	Research and Development Costs
	Research and development costs are comprised primarily of costs for personnel, including salaries and benefits; clinical studies adminstered by third parties and managed by Stemline personnel; materials and supplies to support the Company’s clinical programs; contracted research; manufacturing; related consulting arrangements; costs related to upfront and milestone payments under license agreements; and other expenses incurred to sustain the Company’s overall research and development programs. Internal research and development costs are expensed as incurred. Third-party research and development costs are expensed as the contracted work is performed. In certain circumstances, the Company is required to make advance payments to vendors for goods or services that will be received in the future for use in research and development activities. In such circumstances, the advance payments are deferred and are expensed when activities have been performed or when the goods have been received.
	Income Taxes
	Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to the differences between the financial statement carrying amounts of existing assets and liabilities and the respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.
	The asset and liability method requires that deferred tax assets and liabilities be recorded without consideration as to their realizability. The deferred tax asset primarily includes net operating loss and tax credit carryforwards, accrued expenses not currently deductible and the cumulative temporary differences related to certain research and patent costs, which have been charged to expense in the accompanying statements of operations but have been recorded as assets for income tax purposes. The portion of any deferred tax asset for which it is more likely than not that a tax benefit will not be realized must then be offset by recording a valuation allowance. A valuation allowance has been established against all of the deferred tax assets (see Note 12), as it is more likely than not that these assets will not be realized given the history of operating losses.
	The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not to be sustained upon examination based on the technical merits of the position. The amount of the accrual for which an exposure exists is measured as the largest amount of benefit determined on a cumulative probability basis that the Company believes is more likely than not to be realized upon ultimate settlement of the position.
	Stock-Based Compensation
	The Company accounts for stock-based compensation in accordance with the provisions of ASC 718, Compensation—Stock Compensation. Accordingly, compensation costs related to equity instruments granted are recognized over the requisite service periods of the awards on a straight-line basis at the grant-date fair value calculated using a Black-Scholes option pricing model for stock options and the closing stock price on date of grant for restricted stock. Additionally, under the provisions of ASC 718, the Company is required to include an estimate of the number of awards that will be forfeited in calculating compensation costs. Any changes to the estimated forfeiture rates are accounted for prospectively.
	For stock options granted as consideration for services rendered by non-employees, the Company recognizes expense in accordance with the requirements of ASC Topic 505-50, Equity Based Payments to Non-Employees. Non-employee option grants that do not vest immediately upon grant are recorded as an expense over the vesting period of the underlying stock options. At the end of each financial reporting period prior to vesting, the value of these options, as calculated using the Black-Scholes option-pricing model, is re-measured using the fair value of the Company’s common stock and the non-cash expense recognized during the period is adjusted accordingly. Since the fair market value of options granted to non-employees is subject to change in the future, the amount of the future expense will include fair value re-measurements until the stock options are fully vested.
	Segment information
	The Company reports segment information in accordance with applicable guidance on segment disclosures. The Company has one reportable segment.
	Recent Accounting Pronouncements
	In August 2014, the FASB issued a new Accounting Standards Update ASU 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. ASU 2014-15 provides guidance on management’s responsibility to evaluate whether there is substantial doubt about an organization’s ability to continue as a going concern and to provide related footnote disclosures. The guidance is effective for annual periods ending after December 15, 2016 and interim periods within annual periods beginning after December 15, 2016. Early adoption is permitted.
	In June 2014, The FASB issued Accounting Standards Update (“ASU”) 2014-10, Development Stage Entities (Topic 915):  Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 910, Consolidation.  This ASU’s objective is to improve financial reporting by reducing cost and complexity associated with the incremental reporting requirements for development stage entities.  The Company has previously met the conditions of being a development stage entity and has provided the appropriate disclosures within the financial statements, including inception to date financial reporting.  As a result of this ASU, all incremental reporting requirements for development stage entities including inception to date financial reporting will no longer be required to be disclosed in financial statements.  The effective date of this ASU is for annual reporting periods beginning after December 15, 2014.  However, early adoption is allowed and the Company has early adopted this ASU within the financial statements for 2014, as such, the Company no longer reports inception to date financial information.
	In May 2014, the Financial Accounting Standards Board (“FASB”) issued a comprehensive new revenue recognition Accounting Standards Update, Revenue from Contracts with Customers (Topic 606)” (ASU 2014-09). ASU 2014-09 provides guidance to clarify the principles for recognizing revenue. This guidance includes the required steps to achieve the core principle that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This guidance is effective for fiscal years and interim periods beginning after December 15, 2016. Early adoption is not permitted. The Company expects to adopt this guidance when effective and is currently evaluating the effect that the updated standard will have on its consolidated financial statements and related disclosures.

Net_Loss_Per_Common_Share

Net Loss Per Common Share	12 Months Ended
	Dec. 31, 2014
Net Loss Per Common Share
Net Loss Per Common Share
	3. Net Loss Per Common Share
	The Company accounts for and discloses net loss per share using the treasury stock method.  Net loss per common share, or basic loss per share, is computed by dividing net loss by the weighted-average number of common shares outstanding. Since the Company is in a net loss for all periods presented, diluted net loss per share is not presented since the common stock equivalents would have an anti-dilutive effect on the per share calculation.
	The following table sets forth the computation of basic and diluted net loss per share for the periods indicated:
		Year Ended December 31,
		2014			2013			2012
	Basic and Diluted loss per common share calculation:
	Net loss attributable to common shareholders — basic and diluted	$	(28,829,975	)	$	(24,196,511	)	$	(6,274,782	)
	Basic and diluted weighted-average common shares	12,936,741			10,317,351			3,441,995
	Basic and diluted net loss per share	$	(2.23	)	$	(2.35	)	$	(1.82	)
	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 years ended 2014, 2013, and 2012, 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:
		Year Ended December 31
		2014		2013		2012
	Unvested restricted stock	283,446		229,250		34,506
	Options outstanding	1,643,532		1,228,486		1,819,839
	Warrants	99,529		99,529		—
	Convertible notes	—		—		252,547
	Total	2,026,507		1,557,265		2,106,892

Marketable_Investments

Marketable Investments	12 Months Ended
	Dec. 31, 2014
Marketable Investments
Marketable Investments
	4. Marketable Investments
	The following table summarizes the Company’s cash equivalents and available for sale securities:
		December 31, 2014
				Gross		Gross			Estimated
		Amortized		Unrealized		Unrealized			Fair
		Cost		Gains		Losses			Value
	Cash equivalents:
	Money market funds	$	23,012,140	$	—	$	—		$	23,012,140
	Short-term investments:
	Fixed-income treasury portfolio:
	Fannie Mae	4,863,371		2,338		—			4,865,709
	Federal farm credit bank	11,432,340		3,575		(73		)	11,435,842
	Federal home loan bank	6,859,294		2,381		(567		)	6,861,108
	Freddie Mac	5,811,405		2,133		(50		)	5,813,488
	Total Short-term investments	28,966,410		10,427		(690		)	28,976,147
	Long-term investments:
	Fixed-income treasury portfolio:
	Federal farm credit bank	1,000,455		—		(1,126		)	999,329
	Federal home loan bank	2,250,965		—		(3,426		)	2,247,539
	Freddie Mac	1,400,136		—		(2,184		)	1,397,952
	Total Long-term investments	4,651,556		—		(6,736		)	4,644,820
	Total	$	56,630,106	$	10,427	$	(7,426	)	$	56,633,107
		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:
	Fannie Mae	4,961,941		—		(6,982		)	4,954,959
	Federal farm credit bank	11,476,874		—		(13,701		)	11,463,173
	Federal home loan bank	13,789,246		—		(14,752		)	13,774,494
	Freddie Mac	10,020,626		—		(8,340		)	10,012,286
	Total Long-term investments	40,248,687		—		(43,775		)	40,204,912
	Total	$	81,690,662	$	—	$	(43,775	)	$	81,646,887
	At December 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 remaining contractual maturities of available-for-sale investments classified as long-term were less than two years.
	There were no available-for-sale securities in a continuous unrealized loss position for greater than twelve months at December 31, 2014 and December 31, 2013. The Company has the ability to hold such securities with an unrealized loss until its forecasted recovery. The Company determined that there was no material change in the credit risk of the above investments. As a result, the Company determined it did not hold any investments with an other-than-temporary impairment as of December 31, 2014.

Prepaid_Expenses_and_Other_Cur

Prepaid Expenses and Other Current Assets	12 Months Ended
	Dec. 31, 2014
Prepaid Expenses and Other Current Assets
Prepaid Expenses and Other Current Assets
	5. Prepaid Expenses and Other Current Assets
	Prepaid expenses and other current assets consist of the following at December 31, 2014 and December 31, 2013:
		December 31,		December 31,
		2014		2013
	Prepaid third party vendor costs	$	1,483,817	$	39,630
	Prepaid insurance	46,748		43,321
	Deposits	106,243		209,965
	Total	$	1,636,808	$	292,916

Furniture_and_Fixtures

Furniture and Fixtures	12 Months Ended
	Dec. 31, 2014
Furniture and Fixtures
Furniture and Fixtures
	6. Furniture and Fixtures
	Furniture and fixtures consist of the following at December 31, 2014 and 2013:
		December 31,			December 31,
		2014			2013
	Office furniture and fixtures	$	460,000		$	460,000
	Less accumulated depreciation	(230,000		)	(76,667		)
	Furniture and fixtures, net	$	230,000		$	383,333
	Depreciation expense was $153,333 and $76,667 for the years ended December 31, 2014 and 2013, respectively.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2014
Fair Value Measurements
Fair Value Measurements
	7. Fair Value Measurements
	Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. Assets and liabilities that are measured at fair value are reported using a three-level fair value hierarchy that prioritizes the inputs used to measure fair value. This hierarchy maximizes the use of observable inputs and minimizes the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows:
	Level 1 — Quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.
	Level 2 — Inputs other than quoted prices in active markets that are observable for the asset or liability, either directly or indirectly.
	Level 3 — Inputs that are unobservable for the asset or liability.
	The following fair value hierarchy table presents information about each major category of the Company’s financial assets and liability measured at fair value on a recurring basis as of December 31, 2014 and 2013:
		December 31, 2014
		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)		2014
	Assets:
	Cash and cash equivalents	$	25,007,217		$	—	$	—	$	25,007,217
	Short-term investments	28,976,147							28,976,147
	Long-term investments	4,644,820			—		—		4,644,820
	Total assets at fair value	$	58,628,184		$	—	$	—	$	58,628,184
		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
	There were no transfers between levels in the fair value hierarchy during any of the periods presented herein.
	Level 3 Disclosures
	The changes in fair value of the Company’s Level 3 put option liability during the years ended December 31, 2014, December 31, 2013 and December 31, 2012 were as follows:
		Level 3
	Balance at December 31, 2011	$	99,230
	Fair value adjustment to put option liability included in other income	(68,815		)
	Balance at December 31, 2012	30,415
	Fair value adjustment to put option liability included in other income	(30,415		)
	Balance as of December 31, 2013	—
	Fair value adjustment to put option liability included in other income	—
	Balance as of December 31, 2014	$	—
	For the year ended December 31, 2013, the changes in the fair value of the put option liability resulted from the expiration of the put option in conjunction with the conversion of half of the principal of the 2.45% convertible note, along with accrued interest, into common stock as a result of the IPO.  The balance of the note was converted into common stock in April 2013. No other changes in valuation techniques or inputs occurred during the year ended December 31, 2013.
	For the year ended December 31, 2012, the changes in the fair value of the put option liability resulted from an adjustment to the remaining period to the expected outcome and taking into consideration the July 26, 2012 and November 14, 2012 amendments to the 2.45% convertible note. No other changes in valuation techniques or inputs occurred during the year ended December 31, 2012.
	The fair value of the put option liability was determined utilizing a probability weighted discounted financial model based on management’s assessment of the likelihood of achievement of certain outcomes based on significant inputs not observable in the market, which causes it to be classified as a Level 3 measurement within the fair value hierarchy. The valuation of the put option liability uses assumptions and estimates the Company believes would be made by a market participant in making the same valuation.

Accounts_Payable_and_Accrued_E

Accounts Payable and Accrued Expenses	12 Months Ended
	Dec. 31, 2014
Accounts Payable and Accrued Expenses
Accounts Payable and Accrued Expenses
	8. Accounts Payable and Accrued Expenses
	Accounts payable and accrued expenses consist of the following:
		December 31,
		2014		2013
	Accrued research and development costs	$	1,762,997	$	1,966,360
	Accrued compensation	1,696,728		2,043,704
	Short-term portion of deferred revenue	485,714		286,000
	Accrued legal	164,389		372,267
	Other accrued liabilities	364,014		345,477
	Total accounts payable and accrued expenses	$	4,473,842	$	5,013,808

Capital_Structure

Capital Structure	12 Months Ended
	Dec. 31, 2014
Capital Structure
Capital Structure
	9. Capital Structure
	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, 2014 and 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.
	Representative’s Warrants
	On October 1, 2012, the Company agreed to issue to the representative of the underwriters in the IPO warrants to purchase up to 99,529 shares of the Company’s common stock in the event of a successful public offering.  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.  Based on a successful public offering in January of 2013, these warrants were issued and accounted for as a cost of issuance.  The Company has determined, based upon a Black-Scholes model, that the fair value of the warrants on the date of IPO was $413,146.  The Company has accounted for the fair value of the warrants as a cost of issuance of common stock from the IPO resulting in a charge directly to stockholder’s equity.

Grant_Revenue

Grant Revenue	12 Months Ended
	Dec. 31, 2014
Grant Revenue
Grant Revenue
	10. Grant 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 Disease’s. 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 received an additional $0.5 million during the fourth quarter of 2014 based upon an additional milestone achieved.  The Company could receive the additional $2.0 million based on the completion of certain milestone events.  The Company has recognized approximately $0.3 million and $0.1 million of revenue related to the Leukemia and Lymphoma Society grant for the years ended December 31, 2014 and 2013, which reflects twelve months and three months  of revenue recognized, respectively, on a straight line basis, based on the Company’s best estimates of work performed and qualifying costs incurred. The agreement terminates when there are no longer any payment obligations.

StockBased_Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 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 December 31, 2014, there were 1,172,264 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 $4.4 million, $4.8 million and $0.6 million for the years ended December 31, 2014, 2013 and 2012, respectively. The exercise of stock options and the vesting of restricted stock during the year ended December 31, 2014 generated an income tax deduction of approximately $1.7 million. 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. At such time, the Company utilizes the net operating losses generated by excess stock-based compensation to reduce its income tax payable and the tax benefit is recorded as an increase in additional paid-in-capital. No income tax benefit was recognized in the statements of operations for share-based compensation arrangements for the years ended December 31, 2014, 2013 and 2012.
	The following table summarizes stock-based compensation related to the above plans by expense category for the years ended December 31, 2014, 2013 and 2012:
		Year Ended December 31,
		2014			2013			2012
	Research and development	$	2,907,820		$	3,301,996		$	412,536
	General and administrative	1,528,869			1,545,090			148,486
	Total	$	4,436,689		$	4,847,086		$	561,022
	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 on 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 years ended December 31, 2014, 2013 and 2012, are as follows:
		Year Ended December 31,
		2014		2013		2012
	Risk-free interest rate	1.97	%	2.10	%	0.95	%
	Expected volatility	88.86	%	78.23	%	78.95	%
	Dividend yield	—		—		—
	Expected life	6.20 years		6.26 years		6.25 years
	Due to the lack of trading history, 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 years ended December 31, 2014 and 2013 the Company issued 33,040 and 550,801 shares of the Company’s common stock, respectively, upon the exercise of outstanding stock options and received proceeds of approximately $135,274 and $1.3 million, respectively. There were no exercises of stock options for the year ended December 31, 2012. For the years ended December 31, 2014, 2013 and 2012 the Company realized no tax benefit from the exercise of stock options. As of December 31, 2014, there was approximately $5.5 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 2.3 years. Total unrecognized compensation cost will be adjusted for future changes in estimated forfeitures.
	The Company’s stock options outstanding at December 31, 2014, 2013 and 2012 and changes during the years ended December 31, 2014, 2013 and 2012 are presented below:
		Options		Weighted-			Weighted-		Aggregate
				Average			Average		Intrinsic
				Exercise Price			Remaining		Value
							Contractual Life
	Outstanding at December 31, 2011	1,233,074		$	2.51
	Options granted	621,828		3.3
	Options exercised	—		—
	Options forfeited	(35,063	)	3.3
	Outstanding at December 31, 2012	1,819,839		$	2.76
	Options granted	159,500		19.08
	Options exercised	(550,801	)	2.37
	Options forfeited	(102,052	)	2.71
	Outstanding at December 31, 2013	1,326,486		$	4.89
	Options granted	378,831		21.07
	Options exercised	(33,040	)	4.09
	Options forfeited	(28,745	)	4.86
	Outstanding at December 31, 2014	1,643,532		$	8.64		6.81		$	21,840,758
	Options exercisable at December 31, 2014	982,641		$	4.03		5.7		$	16,232,198
	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 December 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 $0.4 million  and $14.8 million for the years ended December 31, 2014 and 2013, respectively. There were no exercises of stock options for the year ended December 31, 2012.
	Restricted Stock
	The Company grants restricted stock to its employees and directors. Restricted stock is recorded as deferred compensation and charged against income 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 Company’s non-vested restricted stock at December 31, 2014, 2013 and 2012, and changes during the years ended December 31, 2014, 2013 and 2012 are presented below:
		Number of Shares		Weighted-
				Average Grant
				Date Fair Value
				Per Share
	Outstanding at December 31, 2011	—		$	—
	Shares granted	34,506		5.97
	Shares vested	—		—
	Shares forfeited	—		—
	Outstanding at December 31, 2012	34,506		$	5.97
	Shares granted	304,528		18.18
	Shares vested	(65,802	)	11.53
	Shares forfeited	(43,982	)	23.35
	Outstanding at December 31, 2013	229,250		17.34
	Shares granted	138,663		21.9
	Shares vested	(83,690	)	17.99
	Shares forfeited	(777	)	25.05
	Outstanding at December 31, 2014	283,446		$	19.36
	For the year ended December 31, 2014, the Company granted 138,663 shares of restricted stock, at a weighted-average grant date fair value of $21.90 per share amounting to approximately $3.0 million in total aggregate fair value. At December 31, 2014, approximately 283,446 shares remained unvested and there was approximately $3.6 million of unrecognized compensation cost related to restricted stock which is expected to be recognized over a remaining weighted-average period of approximately 2.7 years. The total fair value of restricted stock vested during the year ended December 31, 2014 was approximately $1.5 million. There were no vestings of restricted stock for the year ended 2012.
	Performance Share Awards
Subsequent to the closing of the IPO, certain options and restricted stock began to vest to directors, consultants and key employees. The Company recorded approximately $1.4 million of stock-based compensation expense associated with 573,424 options with a weighted average exercise price of $2.38 and 8,625 shares of restricted stock that fully vested upon consummation of an IPO. In addition, 281,895 options commenced vesting based upon the consummation of the IPO and the Company will record $1.8 million on the vesting of these options over their expected lives.
For awards with performance conditions, such as capital raises, an IPO, a change in control or a sale of the company, no expense is recognized, and no measurement date can occur, until the occurrence of the event is probable.
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 that has been charged against operations related to options granted to non-employees was approximately $0.1 million, $0.8 million, and $0.1 million for the years ended December 31, 2014, 2013 and 2012, respectively.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Taxes
Income Taxes
	12. Income Taxes
	The benefit for income taxes consists of the following for the years ended December 31:
		2014			2013			2012
	Deferred:
	Federal	$	(14,047,679	)	$	(8,861,971	)	$	(1,775,748	)
	State and local	(2,520,711		)	(2,813,740		)	(1,062,155		)
		(16,568,390		)	(11,675,711		)	(2,837,903		)
	Increase in valuation allowance	16,568,390			11,675,711			2,837,903
	Total tax expense	$	—		$	—		$	—
	A reconciliation of the statutory U.S. federal rate to the Company’s effective tax rate is as follows:
		Year Ended December 31,
		2014		2013		2012
	Percent of pre-tax income:
	U.S. federal statutory income tax rate	(34.0	)%	(34.0	)%	(34.0	)%
	State taxes, net of federal benefit	(8.8	)	(11.6	)	(11.3	)
	Permanent items	(14.7	)	(2.6	)	(0.3	)
	Change in valuation allowance	57.5		48.2		45.6
	Effective income tax rate	—	%	—	%	—	%
	The tax effects of temporary differences that gave rise to significant portions of the deferred tax assets were as follows:
		December 31,
		2014			2013
	Current deferred tax assets:
	Accrued expenses	$	1,450,412		$	1,259,692
	Valuation allowance	(1,450,412		)	(1,259,692		)
	Total current deferred tax assets	$	—		$	—
	Noncurrent deferred tax assets:
	Net operating loss carryforwards	$	18,342,986		$	16,374,002
	Research and Development	13,986,047			644,203
	Nonqualified stock compensation	3,255,541			2,188,701
		35,584,574			19,206,906
	Valuation allowance	(35,584,574		)	(19,206,906		)
	Total noncurrent deferred tax assets	$	—		$	—
	In assessing the realizability of deferred tax assets, the Company considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which the temporary differences representing net future deductible amounts become deductible. Due to the Company’s history of losses, the deferred tax assets are fully offset by a valuation allowance at December 31, 2014, 2013 and 2012.
	The following table summarizes carryforwards of net operating losses and tax credits as of December 31, 2014:
		Amount			Expiration
	Federal net operating losses	$	55,475,000	(A)	2023-2034
	State net operating losses	$	55,534,000	(A)	2023-2034
	Research and development credits	$	7,008,000		2023-2034
	(A)Of which $14,867,000 will be a benefit to additional paid in capital upon realization as they relate to excess benefits from stock option exercises.
	The Internal Revenue Code of 1986, as amended (the “Code”) provides for a limitation of the annual use of net operating losses and other tax attributes (such as research and development tax credit carryforwards) following certain ownership changes (as defined by the Code) that could limit the Company’s ability to utilize these carryforwards. At this time, the Company has not completed a study to assess whether an ownership change under section 382 of the Code has occurred, or whether there have been multiple ownership changes since the Company’s formation, due to the costs and complexities associated with such a study. The Company may have experienced various ownership changes, as defined by the Code, as a result of past financing transactions. Accordingly, the Company’s ability to utilize the aforementioned carryforwards may be limited. Additionally, U.S. tax laws limit the time during which these carryforwards may be applied against future taxes. Therefore, the Company may not be able to take full advantage of these carryforwards for federal or state income tax purposes.
	The Company did not have unrecognized tax benefits as of December 31, 2014 and does not expect this to change significantly over the next twelve months. As of December 31, 2014, the Company has not accrued interest or penalties related to uncertain tax positions. The Company’s tax returns for the years ended December 31, 2008 through December 31, 2014 are still subject to examination by major tax jurisdictions.
	The Company will recognize interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2014, 2013 and 2012, the Company had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in the Company’s consolidated statements of operations and comprehensive loss.
	For all years through December 31, 2014, the Company generated research credits but has not conducted a study to document the qualified activities. This study may result in an adjustment to the Company’s research and development credit carryforwards; however, until a study is completed and any adjustment is known, no amounts are being presented as an uncertain tax position for these two years. A full valuation allowance has been provided against the Company’s research and development credits and, if an adjustment is required, this adjustment would be offset by an adjustment to the deferred tax asset established for the research and development credit carryforwards and the valuation allowance.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies
Commitments and Contingencies
	13. Commitments and Contingencies
	License Agreements
	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 $109.3 million upon achieving certain milestones, such as the initiation of clinical trials or the granting of patents. From inception through December 31, 2014, the Company has paid or accrued $2.4 million in payments resulting from the execution of certain agreements, patent approvals, the initiation of sponsor 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”) to fund the activities of S&W to conduct research involving SL-401, a clinical-stage compound that the Company has exclusively licensed. This compound is being developed to treat patients with AML, BPDCN, and other hematologic cancers. 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 a mutant peptide of IL-13Rα2, an ingredient of SL-701, (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), single-digit royalties on net sales, if any, of new products approved utilizing the licensed compounds, 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 the use of a peptide of EphA2, which the Company may use in or packaged with proprietary immunotherapies, including SL-701, 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 relevant to 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, part of which is deferred until March 2013, 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.
	CanBas, Ltd
	On December 26, 2014, we entered into a license agreement with CanBas, Ltd. for SL-801. SL-801 is a small molecule, reversible inhibitor of XPO1. Under the terms of the agreement, CanBas has granted us an exclusive, royalty-bearing, worldwide (excluding Japan, Korea, China and Taiwan) license, under certain patent rights, know-how and materials to research, develop, make, have made, formulate, use, sell, offer to sell and import SL-801, for the treatment of any disease or condition in humans.
	We are responsible to pay technical advisory fees over the next four years of 430 million Japanese Yen (JPY), in aggregate, only if the clinical development continues over this time period. Additionally, we must pay CanBas tiered royalties based on aggregate net sales, by us or our sublicensees, of products containing the licensed compound until the latest date of a period of ten years following the first commercial sale of each product in each country; the date upon which there are no more valid claims or the expiration or termination of the last regulatory exclusivity period. The royalty rates range from low single digits and are tiered up based on annual net sales. We also must make certain payments to CanBas of up to $86 million upon the achievement of specific clinical development, regulatory and sales-based commercial milestones. We have sublicensing rights under the agreement, subject to our paying to CanBas a standard royalty percentage of the payments we receive from a sublicensee.
	The agreement survives until the later of ten years following the first commercial sale of each product in each country; the date upon which there are no more valid claims or the expiration or termination of the last regulatory exclusivity period, after which our license becomes fully paid, irrevocable, perpetual, non-exclusive and royalty-free. We may terminate the license for any or no reason upon 60 days advance written notice to CanBas. If either we or CanBas breach a material obligation under the agreement, and such obligation is not cured within a specified period of time following written notice from the other party, then the non-breaching party may terminate the agreement upon an additional written notice.
	Other
	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.
	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, 2014, the contract services were performed on the initial work order and had been paid by the Company. During 2014, the Company entered into new work order agreements with this vendor totaling approximately $3.4 million, with services to be rendered on these agreements through 2015. The Company has received and paid for services during the twelve months ended December 31, 2014 relating to this agreement in the amount of $1.9 million.
	In October 2013, the Company entered into a clinical trial agreement with a leading research hospital and other participating institutions, relating to the performance of our feasibility/pilot study to evaluate the effects of SL-701.  Services under this contract are expected to be performed through 2017. The Company’s total obligation under the contract is expected to be approximately $1.0 million.
	The Company has agreements in place with three contract research organizations (CRO’s) 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 $21.6 million through 2018.
	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:
	2015	$	607,500
	2016	303,750
	2017	—
		$	911,250
	Rent expense charged to operations was approximately $0.6 million and $0.3 million for the years ended December 31, 2014 and 2013, respectively. Rent expense is included in general and administrative expenses in the Company’s Statement of Operations.

Related_Party_Items

Related Party Items	12 Months Ended
	Dec. 31, 2014
Related Party Items
Related Party Items
	14. 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 stock options. This item is reflected on the Company’s December 31, 2013 balance sheet as a related party receivable.
	Assignment Agreement with the Company’s Chief Executive Officer
	On June 15, 2012, the Company entered into an assignment agreement with Dr. Bergstein, the Company’s Chairman, President and Chief Executive Officer and owner of certain proprietary patent rights and related technology. Pursuant to the assignment agreement, as amended on November 7, 2012, effective immediately prior to the registration statement for the Company’s initial public offering being declared effective by the Securities and Exchange Commission, Dr. Bergstein agrees to assign, sell, transfer and convey to the Company all of his right, title and interest in and to these patent rights and related technology in exchange for $2.0 million in cash or a combination of cash and shares of Company common stock, payable only if, within five years of the date of transfer, the Company either (i) has a change in control, as defined in the assignment agreement, or (ii) achieves a market capitalization of at least $200 million for a prescribed period. Under the terms of the assignment agreement, as amended, 50% of such payment shall be paid in cash and the remaining 50% may be paid in shares of Company common stock, or a combination of cash and common stock, as determined by the Company. If the Company elects to settle payment in shares, the Company will value the shares at the date of issuance. None of the assigned patent rights and related technology has alternative future uses, nor have they reached a stage of technological feasibility. The Company accounted for this transaction as an asset acquisition as it achieved a market capitalization of $200 million for the prescribed period because it did not acquire any processes or activities in addition to the assigned rights and technology. The Company has recorded the entire purchase price to acquire in-process research and development expense for the year ended December 31, 2013. The assignment agreement does not contain any vesting or rescission/refund provisions.

Other_Income

Other Income	12 Months Ended
	Dec. 31, 2014
Other Income
Other Income
	15. Other Income
	The components of other income for the years ended December 31, 2014, 2013 and 2012 are as follows:
	Other Income:	2014		2013		2012
	Mark-to-market valuation adjustment to Put Option	$	—	$	30,415	$	68,615
	New York City Biotechnology R&D tax credit	—		249,477		203,806
	Other	3,607		795		29,263
	Total other income	$	3,607	$	280,687	$	301,684
	Other income includes funds from the City of New York for the 2013 and 2012 Biotechnology Tax Credit program. The income from these programs is a reimbursement of expenses directly related to specific qualifying research programs in accordance with the guidelines of the respective tax credit programs and there are no performance or refund obligations. These expenses were incurred in prior periods and therefore the income was recorded when the funds were received. Other income also includes the mark-to-market of the put option liability associated with the issuance of convertible notes.  See Note 6 for further discussion of the Put Option.

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events
Subsequent Events
	16. Subsequent Events
	On January 8, 2015, the Company completed a follow-on public offering, selling 3,800,000 shares at an offering price of $15.75 per share. On February 10, 2015, the underwriters exercised their over-allotment option to purchase an additional 553,877 shares at the offering price of $15.75 per share. Aggregate gross proceeds from the Secondary Offering, including the exercise of the over-allotment option, were $68.6 million, and net cash proceeds received after underwriting fees and offering expenses were approximately $64.1 million.

Selected_Quarterly_Financial_D

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2014
Selected Quarterly Financial Data (Unaudited)
Selected Quarterly Financial Data (Unaudited)
	17. Selected Quarterly Financial Data (Unaudited)
		Quarters Ended
		March			June			September			December 31
		31			30			30
	2014
	Net loss attributable to common stockholders	$	(8,999,926	)	$	(6,012,698	)	$	(6,885,157	)	$	(6,932,194	)
	Basic and diluted net loss per common share	$	(0.70	)	$	(0.47	)	$	(0.53	)	$	(0.53	)
	2013
	Net loss attributable to common stockholders	$	(5,505,646	)	$	(5,450,638	)	$	(5,573,524	)	$	(7,666,703	)
	Basic and diluted net loss per common share	$	(0.90	)	$	(0.55	)	$	(0.45	)	$	(0.60	)

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Summary of Significant Accounting Policies
Use of Estimates
	Use of Estimates
	The preparation of financial statements in conformity with generally accepted accounting principles in the US (US GAAP) requires management to make estimates and assumptions that affect the reported financial position at the date of the financial statements and the reported results of operations during the reporting period.  Such estimates and assumptions affect the reported amounts of assets, liabilities, revenues and expenses and disclosure of contingent assets and liabilities in the financial statements and accompanying notes.  Actual results could differ from those estimates.
Cash Equivalents
	Cash Equivalents
	Cash equivalents consist of highly liquid instruments purchased with an original maturity of three months or less. At December 31, 2014 and 2013, cash equivalents consist of deposits in financial institutions. The Company maintains its cash deposits and cash equivalents with well-known and stable financial institutions.
Concentration of Credit Risk
	Concentration of Credit Risk
	Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash equivalents. The Company invests its excess cash in major U.S. banks and financial institutions, and its deposits, at times, exceed federally insured limits. The Company has not experienced any losses from credit risks.
Investments
	Investments
	The Company’s investments are considered to be available-for-sale and are carried at fair value. Unrealized gains and losses, if any, are reported as a separate component of stockholders’ equity (deficit) and are not reflected in the statements of operations until a sale transaction occurs or when declines in fair value are deemed to be other-than-temporary (“OTT”). The cost of investments classified as available-for-sale are adjusted for the amortization of premiums and accretion of discounts to maturity and recorded in other expense and other income, respectively. Realized gains and losses, if any, are determined using the specific identification method and are included in other income and other expense, respectively. Investments with original maturities beyond 90 days at the date of purchase and which mature at, or less than twelve months from, the balance sheet date are classified as current. Investments with a maturity beyond twelve months from the balance sheet date are classified as long-term.
Fair Value of Financial Instruments
	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 liabilities. Cash and cash equivalents, and long-term investments are carried at fair value (see Note 6). Financial instruments including other current assets, accounts payable and accrued liabilities are carried at cost, which approximate fair value given their short-term nature.
Other-Than-Temporary Impairment Losses on Investments
	Other-Than-Temporary Impairment Losses on Investments
	The Company regularly monitors its available-for-sale portfolio to evaluate the necessity of recording impairment losses for OTT declines in the fair value of investments. Management makes this determination through the consideration of various factors such as management’s intent and ability to retain an investment for a period of time sufficient to allow for any anticipated recovery in market value. OTT impairment losses result in a permanent reduction of the cost basis of an investment. For the years ended December 31, 2014 and 2013 the Company did not realize any investment losses due to OTT declines in fair value.
Furniture and Fixtures
	Furniture and Fixtures
	Furniture and fixtures are stated at cost, less accumulated depreciation. Depreciation is provided over the estimated useful lives of the respective assets, which is three years, using the straight-line method.
Impairment of Long-Lived Assets
	Impairment of Long-Lived Assets
	The Company reviews long-lived assets, (the Company’s furniture and fixtures), for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. The impairment loss, if recognized, would be based on the excess of the carrying value of the impaired asset over its respective fair value. The Company purchased fixed assets during 2013. For the years ended December 31, 2014 and 2013 the Company did not realize any impairment losses.
Grant Revenue Recognition
	Grant Revenue Recognition
	The Company has not yet generated any revenue from product sales. The Company’s sole source of revenue is grant revenue related to a $1.0 million research grant received from the Leukemia and Lymphoma Society in October 2013 and an additional $0.5 million that was received during the fourth quarter of 2014 based upon an additional milestone achieved.  This research grant was awarded to the Company to support funding some of the costs for the upcoming SL-401 clinical trials.  Grant payments received prior to the Company’s performance of work required by the terms of the research grant are recorded as deferred revenue and recognized as grant revenue once work is performed and qualifying costs are incurred. The Company has recognized approximately $0.3 million and $0.1 million of revenue related to the Leukemia and Lymphoma Society grant for the years ended December 31, 2014 and 2013, respectively, which reflect twelve months and three months of revenue recognized, respectively, on a straight line basis, based on the Company’s best estimates of the timing of work to be performed and qualifying costs incurred.
Accrued Clinical Development Costs
	Accrued Clinical Development Costs
	Outside research costs are a component of research and development expense. These expenses include fees paid to contract research organizations and other service providers that conduct certain clinical and product development activities on behalf of the Company. Depending upon the timing of payments to the service providers, the Company recognizes prepaid expenses or accrued expenses related to these costs. These accrued or prepaid expenses are based on management’s estimates of the work performed under service agreements, milestones achieved and experience with similar contracts. The Company monitors each of these factors and adjusts estimates accordingly.
Research and Development Costs
	Research and Development Costs
	Research and development costs are comprised primarily of costs for personnel, including salaries and benefits; clinical studies adminstered by third parties and managed by Stemline personnel; materials and supplies to support the Company’s clinical programs; contracted research; manufacturing; related consulting arrangements; costs related to upfront and milestone payments under license agreements; and other expenses incurred to sustain the Company’s overall research and development programs. Internal research and development costs are expensed as incurred. Third-party research and development costs are expensed as the contracted work is performed. In certain circumstances, the Company is required to make advance payments to vendors for goods or services that will be received in the future for use in research and development activities. In such circumstances, the advance payments are deferred and are expensed when activities have been performed or when the goods have been received.
Income Taxes
	Income Taxes
	Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to the differences between the financial statement carrying amounts of existing assets and liabilities and the respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.
	The asset and liability method requires that deferred tax assets and liabilities be recorded without consideration as to their realizability. The deferred tax asset primarily includes net operating loss and tax credit carryforwards, accrued expenses not currently deductible and the cumulative temporary differences related to certain research and patent costs, which have been charged to expense in the accompanying statements of operations but have been recorded as assets for income tax purposes. The portion of any deferred tax asset for which it is more likely than not that a tax benefit will not be realized must then be offset by recording a valuation allowance. A valuation allowance has been established against all of the deferred tax assets (see Note 12), as it is more likely than not that these assets will not be realized given the history of operating losses.
	The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not to be sustained upon examination based on the technical merits of the position. The amount of the accrual for which an exposure exists is measured as the largest amount of benefit determined on a cumulative probability basis that the Company believes is more likely than not to be realized upon ultimate settlement of the position.
Stock-Based Compensation
	Stock-Based Compensation
	The Company accounts for stock-based compensation in accordance with the provisions of ASC 718, Compensation—Stock Compensation. Accordingly, compensation costs related to equity instruments granted are recognized over the requisite service periods of the awards on a straight-line basis at the grant-date fair value calculated using a Black-Scholes option pricing model for stock options and the closing stock price on date of grant for restricted stock. Additionally, under the provisions of ASC 718, the Company is required to include an estimate of the number of awards that will be forfeited in calculating compensation costs. Any changes to the estimated forfeiture rates are accounted for prospectively.
	For stock options granted as consideration for services rendered by non-employees, the Company recognizes expense in accordance with the requirements of ASC Topic 505-50, Equity Based Payments to Non-Employees. Non-employee option grants that do not vest immediately upon grant are recorded as an expense over the vesting period of the underlying stock options. At the end of each financial reporting period prior to vesting, the value of these options, as calculated using the Black-Scholes option-pricing model, is re-measured using the fair value of the Company’s common stock and the non-cash expense recognized during the period is adjusted accordingly. Since the fair market value of options granted to non-employees is subject to change in the future, the amount of the future expense will include fair value re-measurements until the stock options are fully vested.
Segment information
	Segment information
	The Company reports segment information in accordance with applicable guidance on segment disclosures. The Company has one reportable segment.
Recent Accounting Pronouncements
	Recent Accounting Pronouncements
	In August 2014, the FASB issued a new Accounting Standards Update ASU 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. ASU 2014-15 provides guidance on management’s responsibility to evaluate whether there is substantial doubt about an organization’s ability to continue as a going concern and to provide related footnote disclosures. The guidance is effective for annual periods ending after December 15, 2016 and interim periods within annual periods beginning after December 15, 2016. Early adoption is permitted.
	In June 2014, The FASB issued Accounting Standards Update (“ASU”) 2014-10, Development Stage Entities (Topic 915):  Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 910, Consolidation.  This ASU’s objective is to improve financial reporting by reducing cost and complexity associated with the incremental reporting requirements for development stage entities.  The Company has previously met the conditions of being a development stage entity and has provided the appropriate disclosures within the financial statements, including inception to date financial reporting.  As a result of this ASU, all incremental reporting requirements for development stage entities including inception to date financial reporting will no longer be required to be disclosed in financial statements.  The effective date of this ASU is for annual reporting periods beginning after December 15, 2014.  However, early adoption is allowed and the Company has early adopted this ASU within the financial statements for 2014, as such, the Company no longer reports inception to date financial information.
	In May 2014, the Financial Accounting Standards Board (“FASB”) issued a comprehensive new revenue recognition Accounting Standards Update, Revenue from Contracts with Customers (Topic 606)” (ASU 2014-09). ASU 2014-09 provides guidance to clarify the principles for recognizing revenue. This guidance includes the required steps to achieve the core principle that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This guidance is effective for fiscal years and interim periods beginning after December 15, 2016. Early adoption is not permitted. The Company expects to adopt this guidance when effective and is currently evaluating the effect that the updated standard will have on its consolidated financial statements and related disclosures.

Net_Loss_Per_Common_Share_Tabl

Net Loss Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2014
Net Loss Per Common Share
Schedule of computation of basic and diluted net loss per share
		Year Ended December 31,
		2014			2013			2012
	Basic and Diluted loss per common share calculation:
	Net loss attributable to common shareholders — basic and diluted	$	(28,829,975	)	$	(24,196,511	)	$	(6,274,782	)
	Basic and diluted weighted-average common shares	12,936,741			10,317,351			3,441,995
	Basic and diluted net loss per share	$	(2.23	)	$	(2.35	)	$	(1.82	)
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
		Year Ended December 31
		2014		2013		2012
	Unvested restricted stock	283,446		229,250		34,506
	Options outstanding	1,643,532		1,228,486		1,819,839
	Warrants	99,529		99,529		—
	Convertible notes	—		—		252,547
	Total	2,026,507		1,557,265		2,106,892

Marketable_Investments_Tables

Marketable Investments (Tables)	12 Months Ended
	Dec. 31, 2014
Marketable Investments
Summary of cash equivalents and available for sale of securities
		December 31, 2014
				Gross		Gross			Estimated
		Amortized		Unrealized		Unrealized			Fair
		Cost		Gains		Losses			Value
	Cash equivalents:
	Money market funds	$	23,012,140	$	—	$	—		$	23,012,140
	Short-term investments:
	Fixed-income treasury portfolio:
	Fannie Mae	4,863,371		2,338		—			4,865,709
	Federal farm credit bank	11,432,340		3,575		(73		)	11,435,842
	Federal home loan bank	6,859,294		2,381		(567		)	6,861,108
	Freddie Mac	5,811,405		2,133		(50		)	5,813,488
	Total Short-term investments	28,966,410		10,427		(690		)	28,976,147
	Long-term investments:
	Fixed-income treasury portfolio:
	Federal farm credit bank	1,000,455		—		(1,126		)	999,329
	Federal home loan bank	2,250,965		—		(3,426		)	2,247,539
	Freddie Mac	1,400,136		—		(2,184		)	1,397,952
	Total Long-term investments	4,651,556		—		(6,736		)	4,644,820
	Total	$	56,630,106	$	10,427	$	(7,426	)	$	56,633,107
		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:
	Fannie Mae	4,961,941		—		(6,982		)	4,954,959
	Federal farm credit bank	11,476,874		—		(13,701		)	11,463,173
	Federal home loan bank	13,789,246		—		(14,752		)	13,774,494
	Freddie Mac	10,020,626		—		(8,340		)	10,012,286
	Total Long-term investments	40,248,687		—		(43,775		)	40,204,912
	Total	$	81,690,662	$	—	$	(43,775	)	$	81,646,887

Prepaid_Expenses_and_Other_Cur1

Prepaid Expenses and Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2014
Prepaid Expenses and Other Current Assets
Schedule of prepaid expenses and other current assets
		December 31,		December 31,
		2014		2013
	Prepaid third party vendor costs	$	1,483,817	$	39,630
	Prepaid insurance	46,748		43,321
	Deposits	106,243		209,965
	Total	$	1,636,808	$	292,916

Furniture_and_Fixtures_Tables

Furniture and Fixtures (Tables)	12 Months Ended
	Dec. 31, 2014
Furniture and Fixtures
Schedule of furniture and fixtures
		December 31,			December 31,
		2014			2013
	Office furniture and fixtures	$	460,000		$	460,000
	Less accumulated depreciation	(230,000		)	(76,667		)
	Furniture and fixtures, net	$	230,000		$	383,333

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Measurements
Schedule of assets and liabilities measured at fair value on recurring basis
		December 31, 2014
		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)		2014
	Assets:
	Cash and cash equivalents	$	25,007,217		$	—	$	—	$	25,007,217
	Short-term investments	28,976,147							28,976,147
	Long-term investments	4,644,820			—		—		4,644,820
	Total assets at fair value	$	58,628,184		$	—	$	—	$	58,628,184
		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
Schedule of changes in fair value of the Company's Level 3 put option liability
		Level 3
	Balance at December 31, 2011	$	99,230
	Fair value adjustment to put option liability included in other income	(68,815		)
	Balance at December 31, 2012	30,415
	Fair value adjustment to put option liability included in other income	(30,415		)
	Balance as of December 31, 2013	—
	Fair value adjustment to put option liability included in other income	—
	Balance as of December 31, 2014	$	—

Accounts_Payable_and_Accrued_E1

Accounts Payable and Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2014
Accounts Payable and Accrued Expenses
Schedule of components of accounts payable and accrued expenses
		December 31,
		2014		2013
	Accrued research and development costs	$	1,762,997	$	1,966,360
	Accrued compensation	1,696,728		2,043,704
	Short-term portion of deferred revenue	485,714		286,000
	Accrued legal	164,389		372,267
	Other accrued liabilities	364,014		345,477
	Total accounts payable and accrued expenses	$	4,473,842	$	5,013,808

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2014
Stock-Based Compensation
Schedule of stock-based compensation by expense category
		Year Ended December 31,
		2014			2013			2012
	Research and development	$	2,907,820		$	3,301,996		$	412,536
	General and administrative	1,528,869			1,545,090			148,486
	Total	$	4,436,689		$	4,847,086		$	561,022
Schedule of weighted-average key assumptions used in determining the fair value of options
		Year Ended December 31,
		2014		2013		2012
	Risk-free interest rate	1.97	%	2.10	%	0.95	%
	Expected volatility	88.86	%	78.23	%	78.95	%
	Dividend yield	—		—		—
	Expected life	6.20 years		6.26 years		6.25 years
Summary of stock option activity
		Options		Weighted-			Weighted-		Aggregate
				Average			Average		Intrinsic
				Exercise Price			Remaining		Value
							Contractual Life
	Outstanding at December 31, 2011	1,233,074		$	2.51
	Options granted	621,828		3.3
	Options exercised	—		—
	Options forfeited	(35,063	)	3.3
	Outstanding at December 31, 2012	1,819,839		$	2.76
	Options granted	159,500		19.08
	Options exercised	(550,801	)	2.37
	Options forfeited	(102,052	)	2.71
	Outstanding at December 31, 2013	1,326,486		$	4.89
	Options granted	378,831		21.07
	Options exercised	(33,040	)	4.09
	Options forfeited	(28,745	)	4.86
	Outstanding at December 31, 2014	1,643,532		$	8.64		6.81		$	21,840,758
	Options exercisable at December 31, 2014	982,641		$	4.03		5.7		$	16,232,198
Summary of non-vested restricted stock activity
		Number of Shares		Weighted-
				Average Grant
				Date Fair Value
				Per Share
	Outstanding at December 31, 2011	—		$	—
	Shares granted	34,506		5.97
	Shares vested	—		—
	Shares forfeited	—		—
	Outstanding at December 31, 2012	34,506		$	5.97
	Shares granted	304,528		18.18
	Shares vested	(65,802	)	11.53
	Shares forfeited	(43,982	)	23.35
	Outstanding at December 31, 2013	229,250		17.34
	Shares granted	138,663		21.9
	Shares vested	(83,690	)	17.99
	Shares forfeited	(777	)	25.05
	Outstanding at December 31, 2014	283,446		$	19.36

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Taxes
Schedule of components of benefit for income taxes
		2014			2013			2012
	Deferred:
	Federal	$	(14,047,679	)	$	(8,861,971	)	$	(1,775,748	)
	State and local	(2,520,711		)	(2,813,740		)	(1,062,155		)
		(16,568,390		)	(11,675,711		)	(2,837,903		)
	Increase in valuation allowance	16,568,390			11,675,711			2,837,903
	Total tax expense	$	—		$	—		$	—
Schedule of reconciliation of the statutory U.S. federal rate to the Company's effective tax rate
		Year Ended December 31,
		2014		2013		2012
	Percent of pre-tax income:
	U.S. federal statutory income tax rate	(34.0	)%	(34.0	)%	(34.0	)%
	State taxes, net of federal benefit	(8.8	)	(11.6	)	(11.3	)
	Permanent items	(14.7	)	(2.6	)	(0.3	)
	Change in valuation allowance	57.5		48.2		45.6
	Effective income tax rate	—	%	—	%	—	%
Schedule of tax effects of temporary differences that gave rise to significant portions of the deferred tax assets
		December 31,
		2014			2013
	Current deferred tax assets:
	Accrued expenses	$	1,450,412		$	1,259,692
	Valuation allowance	(1,450,412		)	(1,259,692		)
	Total current deferred tax assets	$	—		$	—
	Noncurrent deferred tax assets:
	Net operating loss carryforwards	$	18,342,986		$	16,374,002
	Research and Development	13,986,047			644,203
	Nonqualified stock compensation	3,255,541			2,188,701
		35,584,574			19,206,906
	Valuation allowance	(35,584,574		)	(19,206,906		)
	Total noncurrent deferred tax assets	$	—		$	—
Summary of carryforwards of net operating losses and tax credits
		Amount			Expiration
	Federal net operating losses	$	55,475,000	(A)	2023-2034
	State net operating losses	$	55,534,000	(A)	2023-2034
	Research and development credits	$	7,008,000		2023-2034
	(A)Of which $14,867,000 will be a benefit to additional paid in capital upon realization as they relate to excess benefits from stock option exercises.

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies
Schedule of future minimum lease payments
	2015	$	607,500
	2016	303,750
	2017	—
		$	911,250

Other_Income_Tables

Other Income (Tables)	12 Months Ended
	Dec. 31, 2014
Other Income
Summary of components of other income
	Other Income:	2014		2013		2012
	Mark-to-market valuation adjustment to Put Option	$	—	$	30,415	$	68,615
	New York City Biotechnology R&D tax credit	—		249,477		203,806
	Other	3,607		795		29,263
	Total other income	$	3,607	$	280,687	$	301,684

Selected_Quarterly_Financial_D1

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Selected Quarterly Financial Data (Unaudited)
Schedule of selected quarterly financial data
		Quarters Ended
		March			June			September			December 31
		31			30			30
	2014
	Net loss attributable to common stockholders	$	(8,999,926	)	$	(6,012,698	)	$	(6,885,157	)	$	(6,932,194	)
	Basic and diluted net loss per common share	$	(0.70	)	$	(0.47	)	$	(0.53	)	$	(0.53	)
	2013
	Net loss attributable to common stockholders	$	(5,505,646	)	$	(5,450,638	)	$	(5,573,524	)	$	(7,666,703	)
	Basic and diluted net loss per common share	$	(0.90	)	$	(0.55	)	$	(0.45	)	$	(0.60	)

Organization_and_Basis_of_Pres1

Organization and Basis of Presentation (Details) (USD $)	0 Months Ended					12 Months Ended			137 Months Ended
	22-May-13	22-May-13	16-May-13	Jan. 31, 2013	Jan. 29, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014
						item
Organization and Basis of Presentation
Number of clinical stage programs						2
Net loss from operations						($28,829,975)	($24,196,511)	($6,274,782)	($72,400,000)
Number of shares issued in initial public offering or in secondary public offering			4,137,931	3,317,644
Share price (in dollars per share)	$14.50		$14.50	$10	$10
Number of shares issued pursuant to an option granted to the underwriters to cover over-allotments	620,689				497,647
Aggregate gross proceeds from initial public offering				38,200,000
Net proceeds received after underwriting fees and offering expenses				32,300,000
Principal amount of convertible debt converted				1,400,000
Number of shares of common stock issued upon conversion of debt				166,769
Compensation expense related to certain bonuses and salary increases payable upon continued employment and the occurrence of a specified financing				1,500,000
Stock-based compensation expense for awards that fully vested upon consummation of IPO (in dollars)				1,400,000
Aggregate gross proceeds from secondary public offering		69,000,000
Proceeds from secondary public offering net of underwriting fees and offering expenses		$64,500,000					$97,708,506

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2014
Furniture and Fixtures
Estimated useful lives	P3Y

Summary_of_Significant_Account3

Summary of Significant Accounting Policies (Details 2) (USD $)	1 Months Ended	3 Months Ended	12 Months Ended
	Oct. 31, 2013	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
			item
Revenue recognition
Research grant received from the Leukemia and Lymphoma Society			$335,287	$71,000
Grant proceeds received	$1,000,000	$500,000
Segment information
Number of reportable segments			1

Net_Loss_Per_Common_Share_Deta

Net Loss Per Common Share (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basic and diluted net loss per common share calculation:
Net loss attributable to common shareholders - basic and diluted	($6,932,194)	($6,885,157)	($6,012,698)	($8,999,926)	($7,666,703)	($5,573,524)	($5,450,638)	($5,505,646)	($28,829,975)	($24,196,511)	($6,274,782)
Basic and diluted weighted-average common shares									12,936,741	10,317,351	3,441,995
Effect of dilutive securities:
Basic and diluted net loss per share (in dollars per share)	($0.53)	($0.53)	($0.47)	($0.70)	($0.60)	($0.45)	($0.55)	($0.90)	($2.23)	($2.35)	($1.82)

Net_Loss_Per_Common_Share_Deta1

Net Loss Per Common Share (Details 2)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net Loss Per Common Share
Potentially dilutive securities excluded from the computation of earnings per share (in shares)	2,026,507	1,557,265	2,106,892
Restricted stock
Net Loss Per Common Share
Potentially dilutive securities excluded from the computation of earnings per share (in shares)	283,446	229,250	34,506
Options outstanding
Net Loss Per Common Share
Potentially dilutive securities excluded from the computation of earnings per share (in shares)	1,643,532	1,228,486	1,819,839
Warrants
Net Loss Per Common Share
Potentially dilutive securities excluded from the computation of earnings per share (in shares)	99,529	99,529
Convertible Notes.
Net Loss Per Common Share
Potentially dilutive securities excluded from the computation of earnings per share (in shares)			252,547

Marketable_Investments_Details

Marketable Investments (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Cash equivalents and available for sale securities
Total Gross Unrealized Gains	$10,427
Total Gross Unrealized Losses	-7,426	-43,775
Long-term investments
Cash equivalents and available for sale securities
Amortized Cost	4,651,556	40,248,687
Gross Unrealized Losses	-6,736	-43,775
Estimated Fair Value	4,644,820	40,204,912
Long-term investments | Maximum
Cash equivalents and available for sale securities
Remaining contractual maturity	2 years
Long-term investments | Federal home loan bank
Cash equivalents and available for sale securities
Amortized Cost	2,250,965	13,789,246
Gross Unrealized Losses	-3,426	-14,752
Estimated Fair Value	2,247,539	13,774,494
Long-term investments | Federal farm credit bank
Cash equivalents and available for sale securities
Amortized Cost	1,000,455	11,476,874
Gross Unrealized Losses	-1,126	-13,701
Estimated Fair Value	999,329	11,463,173
Long-term investments | Freddie Mac
Cash equivalents and available for sale securities
Amortized Cost	1,400,136	10,020,626
Gross Unrealized Losses	-2,184	-8,340
Estimated Fair Value	1,397,952	10,012,286
Long-term investments | Fannie Mae
Cash equivalents and available for sale securities
Amortized Cost		4,961,941
Gross Unrealized Losses		-6,982
Estimated Fair Value		4,954,959
Short-term investments
Cash equivalents and available for sale securities
Amortized Cost	28,966,410
Gross Unrealized Gains	10,427
Gross Unrealized Losses	-690
Estimated Fair Value	28,976,147
Short-term investments | Maximum
Cash equivalents and available for sale securities
Remaining contractual maturity	12 months
Short-term investments | Federal home loan bank
Cash equivalents and available for sale securities
Amortized Cost	6,859,294
Gross Unrealized Gains	2,381
Gross Unrealized Losses	-567
Estimated Fair Value	6,861,108
Short-term investments | Federal farm credit bank
Cash equivalents and available for sale securities
Amortized Cost	11,432,340
Gross Unrealized Gains	3,575
Gross Unrealized Losses	-73
Estimated Fair Value	11,435,842
Short-term investments | Freddie Mac
Cash equivalents and available for sale securities
Amortized Cost	5,811,405
Gross Unrealized Gains	2,133
Gross Unrealized Losses	-50
Estimated Fair Value	5,813,488
Short-term investments | Fannie Mae
Cash equivalents and available for sale securities
Amortized Cost	4,863,371
Gross Unrealized Gains	2,338
Estimated Fair Value	4,865,709
Estimated Fair Value
Cash equivalents and available for sale securities
Total	56,633,107	81,646,887
Amortized Cost
Cash equivalents and available for sale securities
Total	56,630,106	81,690,662
Money market funds | Amortized Cost.
Cash equivalents and available for sale securities
Cash equivalents	23,012,140	41,441,975
Money market funds | Estimated Fair Value
Cash equivalents and available for sale securities
Cash equivalents	$23,012,140	$41,441,975

Marketable_Investments_Details1

Marketable Investments (Details 2) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Fair Value Measurements
Available-for-sale securities in a continuous unrealized loss position for greater than twelve months	$0	$0

Prepaid_Epenses_and_Other_Curr

Prepaid Epenses and Other Current Assets (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Prepaid Expenses and Other Current Assets
Prepaid third party vendor costs	$1,483,817	$39,630
Prepaid insurance	46,748	43,321
Deposits	106,243	209,965
Total	$1,636,808	$292,916

Furniture_and_Fixtures_Details

Furniture and Fixtures (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Furniture and fixtures
Less accumulated depreciation	($230,000)	($76,667)
Furniture and fixtures, net	230,000	383,333
Depreciation expense	153,333	76,667
Office furniture and fixtures
Furniture and fixtures
Office furniture and fixtures, Gross	$460,000	$460,000

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
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:
Short-term investments	28,976,147
Long-term investments	4,644,820	40,204,912
2.45% Convertible Notes
Assets:
Interest rate (as a percent)		2.45%	2.45%
Recurring basis | Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	25,007,217	44,200,420
Short-term investments	28,976,147
Long-term investments	4,644,820	40,204,912
Total assets at fair value	58,628,184	84,405,332
Recurring basis | Estimated Fair Value
Assets:
Cash and cash equivalents	25,007,217	44,200,420
Short-term investments	28,976,147
Long-term investments	4,644,820	40,204,912
Total assets at fair value	$58,628,184	$84,405,332

Fair_Value_Measurements_Detail1

Fair Value Measurements (Details 2) (Put option liability, USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Put option liability
Changes in fair value of Level 3 put option liability
Balance at the beginning of the period	$30,415	$99,230
Fair value adjustment to put option liability included in other income	-30,415	-68,815
Balance at the end of the period		$30,415

Accounts_Payable_and_Accrued_E2

Accounts Payable and Accrued Expenses (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Accounts payable and accrued expenses
Accrued research and development costs	$1,762,997	$1,966,360
Accrued compensation	1,696,728	2,043,704
Short-term portion of deferred revenue	485,714	286,000
Accrued legal	164,389	372,267
Other accrued liabilities	364,014	345,477
Total accounts payable and accrued expenses	$4,473,842	$5,013,808

Capital_Structure_Details

Capital Structure (Details) (USD $)	0 Months Ended	1 Months Ended		12 Months Ended
	Jun. 19, 2013	Jan. 31, 2013	Oct. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Oct. 02, 2012
				item
Capital Structure
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
Fair value of warrants		$413,146

Grant_Revenue_Details

Grant Revenue (Details) (USD $)	1 Months Ended	3 Months Ended	12 Months Ended
	Oct. 31, 2013	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Grant Revenue
Maximum amount of grants to be received from the Leukemia and Lymphoma Society	$3,500,000
Grant proceeds received	1,000,000	500,000
Grant revenue			335,287	71,000
Amount of grants to be received upon completion of certain milestone	$2,000,000

StockBased_Compensation_Detail

Stock-Based Compensation (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock Option Plan
Income tax deduction from exercise of stock options and the vesting of restricted stock	$1,700,000
Tax benefits related to the stock-based compensation costs recognized	0	0	0
Options outstanding
Stock Option Plan
Number of options to purchase common stock outstanding (in shares)	1,643,532	1,326,486	1,819,839	1,233,074
Term of option	10 years
Income tax deduction from exercise of stock options and the vesting of restricted stock	$0	$0	$0
Restricted stock
Stock Option Plan
Number of restricted stock awards outstanding (in shares)	283,446	229,250	34,506
2004 Plan | Options outstanding
Stock Option Plan
Number of options to purchase common stock outstanding (in shares)			1,819,839
2004 Plan | Restricted stock
Stock Option Plan
Number of restricted stock awards outstanding (in shares)			34,506
2012 Plan
Stock Option Plan
Number of common stock shares initially authorized for grant	1,663,727
Term of option	10 years
Shares available for future grants	1,172,264

StockBased_Compensation_Detail1

Stock-Based Compensation (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock-Based Compensation
Stock-based compensation expense	$4,436,689	$4,847,086	$561,022
Research and development
Stock-Based Compensation
Stock-based compensation expense	2,907,820	3,301,996	412,536
General and administrative
Stock-Based Compensation
Stock-based compensation expense	$1,528,869	$1,545,090	$148,486

StockBased_Compensation_Detail2

Stock-Based Compensation (Details 3) (USD $)	0 Months Ended	12 Months Ended
	Jan. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
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
Proceeds from exercise of stock options		$135,274	$1,293,750
Tax benefit from exercise of stock options and the vesting of restricted stock		1,700,000
Options outstanding
Stock-Based Compensation
Term of option		10 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
Risk-free interest rate (as a percent)		1.97%	2.10%	0.95%
Expected volatility (as a percent)		88.86%	78.23%	78.95%
Expected life		6 years 2 months 12 days	6 years 3 months 4 days	6 years 3 months
Dividends paid to stockholders		0
Proceeds from exercise of stock options		135,274	1,300,000
Tax benefit from exercise of stock options and the vesting of restricted stock		0	0	0
Unrecognized compensation expense related to unvested stock options		5,500,000
Weighted average period over which unrecognized compensation expense is expected to be recognized		2 years 3 months 18 days
Options
Outstanding balance at the beginning of the period (in shares)		1,326,486	1,819,839	1,233,074
Options granted (in shares)		378,831	159,500	621,828
Options exercised (in shares)		-33,040	-550,801	0
Options forfeited (in shares)		-28,745	-102,052	-35,063
Outstanding balance at the end of the period (in shares)		1,643,532	1,326,486	1,819,839
Options exercisable (in shares)		982,641
Weighted Average Exercise Price
Outstanding balance at the beginning of the period (in dollars per share)		$4.89	$2.76	$2.51
Options granted (in dollars per share)	$2.38	$21.07	$19.08	$3.30
Options exercised (in dollars per share)		$4.09	$2.37
Options forfeited (in dollars per share)		$4.86	$2.71	$3.30
Outstanding balance at the end of the period (in dollars per share)		$8.64	$4.89	$2.76
Options exercisable (in dollars per share)		$4.03
Weighted-Average Remaining Contractual Life
Outstanding balance at the Beginning of the period		6 years 9 months 22 days
Options exercisable		5 years 8 months 12 days
Aggregate Intrinsic Value
Outstanding balance at the Beginning of the period (in dollars)		21,840,758
Options exercisable (in dollars)		16,232,198
Total intrinsic value of options exercised		$400,000	$14,800,000
Options outstanding | Employees
Stock-Based Compensation
Vesting period		4 years
Options outstanding | Directors
Stock-Based Compensation
Vesting period		3 years

StockBased_Compensation_Detail3

Stock-Based Compensation (Details 4) (USD $)	0 Months Ended	12 Months Ended
	Jan. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Performance Share Awards
Stock-based compensation expense		$4,436,689	$4,847,086	$561,022
Directors, consultants and key employees
Performance Share Awards
Stock-based compensation expense	1,400,000
Non-employees
Performance Share Awards
Stock-based compensation expense		100,000	800,000	100,000
Restricted stock
Number of Shares
Outstanding balance at the beginning of the period (in shares)		229,250	34,506
Shares granted		138,663	304,528	34,506
Shares vested		-83,690	-65,802	0
Shares forfeited		-777	-43,982
Outstanding balance at the end of the period (in shares)		283,446	229,250	34,506
Weighted Average Grant Date Fair Value Per Share
Outstanding balance at the beginning of the period (in dollars per share)		$17.34	$5.97
Shares granted (in dollars per share)		$21.90	$18.18	$5.97
Shares exercised (in dollars per share)		$17.99
Shares vested (in dollars per share)			$11.53
Shares forfeited (in dollars per share)		$25.05	$23.35
Outstanding balance at the end of the period (in dollars per share)		$19.36	$17.34	$5.97
Total aggregate fair value of stock granted		3,000,000
Unrecognized compensation expense related to unvested restricted stock		3,600,000
Remaining weighted-average period for recognizing unrecognized compensation cost		2 years 8 months 12 days
Total fair value of restricted stock vested		1,500,000
Performance Share Awards
Restricted stock that fully vested upon consummation of IPO (in shares)	8,625
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
Options outstanding
Weighted Average Grant Date Fair Value Per Share
Remaining weighted-average period for recognizing unrecognized compensation cost		2 years 3 months 18 days
Performance Share Awards
Options that vested upon consummation of IPO (in shares)	573,424
Weighted average exercise price (in dollars per share)	$2.38	$21.07	$19.08	$3.30
Options that commence vesting upon the occurrence of an IPO or a specified financing (in shares)	281,895
Expected stock-based compensation expense on vesting of options (in dollars)	$1,800,000
Options outstanding | Directors
Stock-Based Compensation
Vesting period		3 years

Income_Taxes_Details

Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred:
Federal	($14,047,679)	($8,861,971)	($1,775,748)
State and local	-2,520,711	-2,813,740	-1,062,155
Total	-16,568,390	-11,675,711	-2,837,903
Increase in valuation allowance	16,568,390	11,675,711	2,837,903
Percent of pre-tax income:
U.S. federal statutory income tax rate (as a percent)	-34.00%	-34.00%	-34.00%
State taxes, net of federal benefit (as a percent)	-8.80%	-11.60%	-11.30%
Permanent items (as a percent)	-14.70%	-2.60%	-0.30%
Change in valuation allowance (as a percent)	57.50%	48.20%	45.60%
Current deferred tax assets:
Accrued expenses	1,450,412	1,259,692
Valuation allowance	-1,450,412	-1,259,692
Noncurrent deferred tax assets:
Net operating loss carryforwards	18,342,986	16,374,002
Research and Development	13,986,047	644,203
Nonqualified stock compensation	3,255,541	2,188,701
Noncurrent deferred tax assets, gross	35,584,574	19,206,906
Valuation allowance	($35,584,574)	($19,206,906)

Income_Taxes_Details_2

Income Taxes (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes
Accrued interest or penalties related to uncertain tax positions	$0	$0	$0
Amount recognized as uncertain tax positions	0
Period for which uncertain tax positions are not presented	2 years
Federal net operating losses
Income Taxes
Net operating losses	55,475,000
Benefit to additional paid in capital upon realization of excess benefits from stock option exercises	14,867,000
Research and development credits
Income Taxes
Credits	7,008,000
State net operating losses
Income Taxes
Net operating losses	$55,534,000

Commitments_and_Contingencies_1

Commitments and Contingencies (Details)	1 Months Ended	12 Months Ended						12 Months Ended		0 Months Ended
	Jul. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Feb. 28, 2013	Dec. 31, 2014	Oct. 02, 2013	Dec. 31, 2014	Dec. 31, 2014	Dec. 26, 2012	Dec. 26, 2012
	USD ($)	USD ($)	USD ($)	Research and development agreements with third parties	Bioprocessing services agreement	New Service Agreements	Investigator initiated clinical trial agreement	Contract research organizations agreement	S&W Agreement	License Agreement Terms	License Agreement Terms
				USD ($)	USD ($)	USD ($)	USD ($)	USD ($)		USD ($)	JPY (¥)
								item
License Agreements
Amount required to be paid upon achievement of certain milestones				$109,300,000						$86,000,000
Amount paid or accrued				2,400,000		1,900,000
Expiry term									10 years	10 years	10 years
Period over which the annual technical advisory fee is to be paid										4 years	4 years
Technical advisory fees											430,000,000
Period of written notice for termination of agreement										60 days	60 days
Period following the first commercial sale until which additional payments are required to be made										10 years	10 years
Contractual Agreement
Contractual agreement value					2,900,000	3,400,000	1,000,000	21,600,000
Number of contracts research organizations								3
Number of clinical-stage product candidates								2
Compensation Arrangements
Monthly lease rent	50,625
Lease agreement term	36 months
Future minimum lease payments
2015		607,500
2016		303,750
Total		911,250
Rent expense		$600,000	$300,000

Related_Party_Items_Details

Related Party Items (Details) (USD $)	0 Months Ended
	Nov. 08, 2012	Jun. 15, 2012	Dec. 31, 2013	Nov. 30, 2013
Related Party Transactions
Receivable from related party			$199,615
Executive
Related Party Transactions
Receivable from related party				200,000
Dr. Bergstein
Related Party Transactions
Aggregate amount to be paid in a combination of cash and company stock		2,000,000
Minimum market capitalization		$200,000,000
Period over which payments will be made		5 years
Percentage of each installment payable in cash per amended assignment agreement	50.00%
Percentage of each installment payable in shares of common stock under the amended assignment agreement	50.00%

Other_Income_Details

Other Income (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Income:
Mark-to-market valuation adjustment to Put Option		$30,415	$68,615
NYC Biotechnology credit		249,477	203,806
Other	3,607	795	29,263
Total other income	$3,607	$280,687	$301,684

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	0 Months Ended					12 Months Ended	0 Months Ended		2 Months Ended
	22-May-13	22-May-13	16-May-13	Jan. 31, 2013	Jan. 29, 2013	Dec. 31, 2013	Feb. 10, 2015	Jan. 08, 2015	Feb. 28, 2015
Subsequent Events
Number of shares issued in initial public offering or in secondary public offering			4,137,931	3,317,644
Share price (in dollars per share)	$14.50		$14.50	$10	$10
Number of shares issued pursuant to an option granted to the underwriters to cover over-allotments	620,689				497,647
Aggregate gross proceeds from secondary public offering		$69,000,000
Proceeds from secondary public offering net of underwriting fees and offering expenses		64,500,000				97,708,506
Subsequent event
Subsequent Events
Number of shares issued in initial public offering or in secondary public offering								3,800,000
Share price (in dollars per share)							$15.75	$15.75
Number of shares issued pursuant to an option granted to the underwriters to cover over-allotments							553,877
Aggregate gross proceeds from secondary public offering									68,600,000
Proceeds from secondary public offering net of underwriting fees and offering expenses									$64,100,000

Selected_Quarterly_Financial_D2

Selected Quarterly Financial Data (Unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Selected Quarterly Financial Data (Unaudited)
Net loss attributable to common stockholders	($6,932,194)	($6,885,157)	($6,012,698)	($8,999,926)	($7,666,703)	($5,573,524)	($5,450,638)	($5,505,646)	($28,829,975)	($24,196,511)	($6,274,782)
Basic and diluted net loss per share (in dollars per share)	($0.53)	($0.53)	($0.47)	($0.70)	($0.60)	($0.45)	($0.55)	($0.90)	($2.23)	($2.35)	($1.82)