Esperion Therapeutics (ESPR) 10-Q 6 Nov 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	9 Months Ended
	Sep. 30, 2013	Nov. 01, 2013
Document and Entity Information	'	'
Entity Registrant Name	'Esperion Therapeutics, Inc.	'
Entity Central Index Key	'0001434868	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-13	'
Amendment Flag	'false	'
Current Fiscal Year End Date	'--12-31	'
Entity Current Reporting Status	'Yes	'
Entity Filer Category	'Non-accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	15,357,413
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
Entity Listing, Par Value Per Share	$0.00	'

Condensed_Balance_Sheets

Condensed Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
Current assets:	'	'
Cash and cash equivalents	$71,895,828	$6,511,521
Prepaid clinical development costs	503,394	367,216
Other prepaid and current assets	535,716	150,325
Assets held for sale	29,108	109,344
Total current assets	72,964,046	7,138,406
Property and equipment, net	78,749	120,210
Intangible assets	55,740	53,825
Investments	13,477,277	'
Total assets	86,575,812	7,312,441
Current liabilities:	'	'
Short term borrowings with related parties, net of debt discount	'	15,241,007
Accrued interest	'	738,192
Accounts payable	1,944,604	476,277
Accrued clinical development costs	449,976	242,171
Warrant liabilities	'	265,323
Other accrued liabilities	948,376	210,329
Total current liabilities	3,342,956	17,173,299
Long-term debt	'	7,528,845
Total liabilities	3,342,956	24,702,144
Commitments and contingencies (Note 5)	'	'
Stockholders' deficit:	'	'
Preferred stock, $0.001 par value; 5,000,000 shares authorized as of September 30, 2013, no shares issued or outstanding at September 30, 2013	'	'
Common stock, $0.001 par value; 120,000,000 shares authorized as of September 30, 2013 and 50,000,000 shares authorized as of December 31, 2012, respectively; 15,357,413 shares issued and 15,335,223 outstanding at September 30, 2013 and 346,478 shares issued and outstanding at December 31, 2012	15,357	346
Additional paid-in capital	141,585,222	609,976
Accumulated other comprehensive income	5,989	'
Deficit accumulated during the development stage	-58,373,712	-41,975,025
Total stockholders' (deficit) equity	83,232,856	-41,364,703
Total liabilities, convertible preferred stock and stockholders' (deficit) equity	86,575,812	7,312,441
Series A preferred stock	'	'
Convertible preferred stock:	'	'
Convertible preferred stock	'	$23,975,000

Condensed_Balance_Sheets_Paren

Condensed Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Dec. 31, 2012
			Series A preferred stock	Series A preferred stock
Preferred stock, par value (in dollars per share)	'	'	$0.00	$0.00
Preferred stock, shares authorized	'	'	0	34,785,000
Preferred stock, shares issued	'	'	0	23,975,000
Preferred stock, shares outstanding	'	'	0	23,975,000
Preferred stock, aggregate liquidation preference (in dollars)	'	'	'	$23,975,000
Preferred stock, par value (in dollars per share)	$0.00	'	'	'
Preferred stock, shares authorized	5,000,000	'	'	'
Preferred stock, shares issued	0	'	'	'
Preferred stock, shares outstanding	0	'	'	'
Common stock, par value (in dollars per share)	$0.00	$0.00	'	'
Common stock, shares authorized	120,000,000	50,000,000	'	'
Common stock, shares issued	15,357,413	346,478	'	'
Common stock, shares outstanding	15,335,223	346,478	'	'

Condensed_Statements_of_Operat

Condensed Statements of Operations and Comprehensive Loss (USD $)	3 Months Ended		9 Months Ended		68 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013
Condensed Statements of Operations and Comprehensive Loss	'	'	'	'	'
Grant income	'	'	'	'	$244,479
Operating expenses:	'	'	'	'	'
Research and development	3,482,673	2,456,412	8,675,688	6,343,846	36,089,549
General and administrative	1,924,150	533,837	4,346,994	1,699,867	15,796,690
Acquired in-process research and development	'	'	'	'	85,612
Total operating expenses	5,406,823	2,990,249	13,022,682	8,043,713	51,971,851
Loss from operations	-5,406,823	-2,990,249	-13,022,682	-8,043,713	-51,727,372
Interest expense	'	-361,426	-936,580	-925,021	-4,320,696
Change in fair value of warrant liability	'	'	-2,586,865	'	-2,554,498
Other income, net	168,389	401	147,440	2,354	228,854
Net loss	-5,238,434	-3,351,274	-16,398,687	-8,966,380	-58,373,712
Net loss per common share (basic and diluted) (in dollars per share)	($0.34)	($10.31)	($3.05)	($28.27)	'
Weighted-average shares outstanding (basic and diluted)	15,253,704	325,023	5,371,335	317,208	'
Other comprehensive income:	'	'	'	'	'
Unrealized gain on investments	5,989	'	5,989	'	'
Total comprehensive loss	($5,232,445)	($3,351,274)	($16,392,698)	($8,966,380)	'

Condensed_Statements_of_Cash_F

Condensed Statements of Cash Flows (USD $)	9 Months Ended		68 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013
Operating activities	'	'	'
Net loss	($16,398,687)	($8,966,380)	($58,373,712)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'	'
Depreciation expense	59,664	106,901	1,436,835
Amortization of debt discount and beneficial conversion	458,993	18,424	575,981
Amortization of debt issuance costs	18,533	6,886	33,911
Amortization of premiums and discounts on investments	12,283	'	12,283
Revaluation of warrants	2,586,865	'	2,554,498
Noncash interest expense on convertible notes	459,055	744,417	3,726,092
Write-off of acquired in-process research and development	'	'	85,612
Stock-based compensation expense	673,244	60,578	930,352
Common stock issued in license agreement	'	'	4,400
Loss related to assets held for sale	29,000	'	324,701
Gain on sale of assets	-140,029	-1,949	-158,488
Changes in assets and liabilities:	'	'	'
Prepaids and other assets	-504,568	-372,943	-1,041,338
Accounts payable	1,299,100	-486,537	1,775,377
Other accrued liabilities	863,535	451,840	1,316,032
Net cash used in operating activities	-10,583,012	-8,438,763	-46,797,464
Investing activities	'	'	'
Purchases of investments	-13,521,020	'	-45,090,186
Proceeds from sales/maturities of investments	'	'	31,515,350
Cash obtained in stock acquisition	'	'	2,500,000
Proceeds from sale of assets	191,265	7,060	942,464
Purchase of property and equipment	-18,203	-10,668	-285,762
Other investing	'	'	50,626
Net cash (used in) provided by investing activities	-13,347,958	-3,608	-10,367,508
Financing activities	'	'	'
Proceeds from initial public offering, net of issuance costs	72,367,768	'	72,367,768
Proceeds from issuance of preferred stock, net of issuance costs	16,824,235	'	40,799,235
Proceeds from exercise of common stock options	123,274	32,362	184,097
Proceeds from warrant issuance	'	141,779	297,690
Proceeds from debt issuance with related parties	'	9,862,220	15,412,010
Net cash provided by financing activities	89,315,277	10,036,361	129,060,800
Net increase (decrease) in cash and cash equivalents	65,384,307	1,593,990	71,895,828
Cash and cash equivalents at beginning of period	6,511,521	1,571,084	'
Cash and cash equivalents at end of period	71,895,828	3,165,074	71,895,828
Supplemental disclosure of cash flow information:	'	'	'
Initial public offering costs not yet paid	169,227	'	169,227
Convertible promissory note	'	'	'
Supplemental disclosure of cash flow information:	'	'	'
Conversion of convertible debt, including accrued interest, into preferred stock	16,623,092	'	16,623,092
Pfizer note	'	'	'
Supplemental disclosure of cash flow information:	'	'	'
Conversion of convertible debt, including accrued interest, into preferred stock	$7,803,000	'	$7,803,000

Condensed_Statements_of_Cash_F1

Condensed Statements of Cash Flows (Parenthetical) (USD $)	Sep. 30, 2013
Convertible promissory note	'
Conversion of convertible promissory notes into preferred stock, accrued interest	$923,092
Pfizer note	'
Conversion of convertible promissory notes into preferred stock, accrued interest	$274,155

The_Company_and_Basis_of_Prese

The Company and Basis of Presentation	9 Months Ended
	Sep. 30, 2013
The Company and Basis of Presentation	'
The Company and Basis of Presentation	'
	1. The Company and Basis of Presentation
	The Company is a biopharmaceutical company focused on the research, development and commercialization of therapies for the treatment of patients with elevated levels of low-density lipoprotein cholesterol (LDL-C) and other cardiometabolic risk factors. ETC-1002, the Company’s lead product candidate, is a novel, first in class, orally available, once-daily small molecule therapy designed to target known lipid and carbohydrate metabolic pathways to reduce levels of LDL-C and to avoid side effects associated with existing LDL-C lowering therapies. The Company owns the exclusive worldwide rights to ETC-1002 and its other product candidates.
	HDL Therapeutics, Inc. (HDL) was incorporated in the state of Delaware on January 22, 2008. On April 28, 2008, HDL acquired all of the capital stock of Esperion Therapeutics, Inc. (Esperion), a wholly owned subsidiary of Pfizer Inc. On May 5, 2008, Esperion was merged with and into HDL and the Company assumed the name Esperion Therapeutics, Inc. (the Company). Its facilities are located in Plymouth, Michigan.
	The Company’s primary activities since incorporation have been recruiting personnel, conducting research and development activities, including pre-clinical and clinical testing, performing business and financial planning, and raising capital. Accordingly, the Company is considered to be in development stage.
	The Company is subject to the risks associated with a development stage entity, which includes the need to: research, develop, and clinically test potential therapeutic products; obtain regulatory approvals for its products and commercialize them, if approved; expand its management and scientific staff; and finance its operations with an ultimate goal of achieving profitable operations.
	The Company has sustained operating losses since inception and expects such losses to continue over the foreseeable future. Management plans to continue to finance operations with a combination of public and private equity issuances, debt arrangements, collaborations and strategic and licensing arrangements. If adequate funds are not available, the Company may not be able to continue the development of its current or future product candidates, or to commercialize its current or future product candidates, if approved.
	Basis of Presentation
	The accompanying condensed financial statements are unaudited and were prepared by the Company in accordance with generally accepted accounting principles in the United States of America (GAAP). In the opinion of management, the Company has made all adjustments, which include only normal recurring adjustments necessary for a fair statement of the Company’s financial position and results of operations for the interim periods presented. Certain information and disclosures normally included in the annual financial statements prepared in accordance with GAAP have been condensed or omitted. These condensed financial statements should be read in conjunction with the audited financial statements and accompanying notes for the year ended December 31, 2012 included in the Company’s final prospectus dated June 25, 2013 filed pursuant to Rule 424(b) under the Securities Act of 1933, as amended, with the Securities and Exchange Commission on June 26, 2013. The results for the three and nine months ended September 30, 2013 are not necessarily indicative of the results to be expected for a full year, any other interim periods or any future year or period.
	Reverse Stock Split
	On June 11, 2013, in connection with its initial public offering (the IPO), the Company effectuated a 1-for-6.986 reverse stock split of its outstanding common stock, which was approved by the Company’s board of directors on June 5, 2013. The reverse stock split resulted in an adjustment to the Series A preferred stock and Series A-1 preferred stock conversion prices to reflect a proportional decrease in the number of shares of common stock to be issued upon conversion. The accompanying financial statements and notes to the financial statements give effect to the reverse stock split for all periods presented. The shares of common stock retained a par value of $0.001 per share. Accordingly, the stockholders’ deficit reflects the reverse stock split by reclassifying from “common stock” to “Additional paid-in capital” in an amount equal to the par value of the decreased shares resulting from the reverse stock split.
	Initial Public Offering
	On July 1, 2013, the Company completed its IPO whereby the Company sold 5,000,000 shares of common stock at a price of $14.00 per share. The shares began trading on the Nasdaq Global Select Market on June 26, 2013. On July 11, 2013, the underwriters exercised their over-allotment option in full and purchased an additional 750,000 shares of common stock at a price of $14.00 per share. The Company received approximately $72.2 million in net proceeds from the IPO, including proceeds from the exercise of the underwriters’ over-allotment option, net of underwriting discounts and commissions and offering expenses. Upon closing of the IPO, all outstanding shares of preferred stock converted into 9,210,999 shares of common stock; and warrants exercisable for convertible preferred stock were automatically converted into warrants exercisable for 277,690 shares of common stock, resulting in the reclassification of the related convertible preferred stock warrant liability of $2,852,188 to additional paid-in capital (See Note 4).
	The following table summarizes the Company’s capitalization upon closing of its initial public offering:
	Total common stock issued as of June 30, 2013	396,414
	Conversion of Series A preferred stock into common stock upon closing of IPO	8,244,781
	Conversion of Series A-1 preferred stock into common stock upon closing of IPO	966,218
	Sales of common stock through IPO	5,000,000
	Common stock issued as of July 1, 2013	14,607,413
	Issuance of common stock to underwriters due to exercise of over-allotment	750,000
	Total common stock issued as of July 11, 2013	15,357,413

Summary_of_Significant_Account

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2013
Summary of Significant Accounting Policies	'
Summary of Significant Accounting Policies	'
	2. Summary of Significant Accounting Policies
	Cash and Cash Equivalents
	The Company invests its excess cash in bank deposits, money market accounts, and short-term investments. The Company considers all highly liquid investments with an original maturity of 90 days or less at the time of purchase to be cash equivalents. Cash equivalents are reported at fair value.
	Investments
	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’ deficit. 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 income (expense), net. Realized gains and losses, if any, are determined using the specific identification method and in other income (expense), net. 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.
	Concentration of Credit Risk
	Cash, cash equivalents, and marketable securities consist of financial instruments that potentially subject the Company to concentrations of credit risk. The Company has established guidelines for investment of its excess cash and believes the guidelines maintain safety and liquidity through diversification of counterparties and maturities.
	Segment Information
	The Company views its operations and manages its business in one operating segment, which is the business of researching, developing and commercializing therapies for the treatment of patients with elevated levels of low-density lipoprotein cholesterol and other cardiometabolic risk factors.
	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 that approximate their carrying value.
	Property and Equipment, Net
	Property and equipment are recorded at cost, less accumulated depreciation. Depreciation is provided using the straight-line method over the estimated useful lives of the respective assets, generally three to ten years. Leasehold improvements are amortized over the lesser of the lease term or the estimated useful lives of the related assets.
	Impairment of Long-Lived Assets
	The Company reviews long-lived assets, including property and equipment, 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. Excluding impairment losses recorded on assets held for sale, no other impairment losses have been recorded through September 30, 2013.
	Research and Development
	Research and development expenses consist of costs incurred to further the Company’s research and development activities and include salaries and related benefits, costs associated with pre-clinical studies and trials, non-clinical activities (such as toxicology studies), regulatory activities, manufacturing activities to support clinical activities, research-related overhead expenses, and fees paid to external service providers that conduct certain research and development, clinical, and manufacturing activities on behalf of the Company. Research and development costs are expensed as incurred.
	In-Process Research and Development
	In April 2008, the Company acquired certain tangible research and development assets and intellectual property from Pfizer Inc. (Pfizer). As the acquired in-process research and development had not reached technological feasibility and had no alternative future uses in connection with this asset and intellectual property acquisition and the related purchase price allocation, the Company expensed $85,612 as in-process research and development costs in 2008.
	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.
	Income Taxes
	The Company utilizes the liability method of accounting for income taxes as required by ASC 740, Income Taxes. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and the tax basis of assets and liabilities and are measured using enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company has incurred operating losses since inception. Accordingly, it is not more likely than not that the Company will realize deferred tax assets and as such, it has recorded a full valuation allowance.
	Warrant Liability
	The Company accounts for its warrants issued in connection with its various financing transactions based upon the characteristics and provisions of the instrument. Warrants classified as derivative liabilities are recorded on the Company’s balance sheet at their fair value on the date of issuance and are marked-to-market on each subsequent reporting period, with the fair value changes recognized in the statement of operations. The warrants are measured using the Black-Scholes option-pricing model subsequent to the pricing of the Company’s IPO and a Monte Carlo valuation model for previous periods which are based, in part, upon inputs where there is little or no market data, requiring the Company to develop its own independent assumptions. The Company will continue to adjust the liability for changes in the fair value of these warrants until the earlier of the exercise of the warrants, the expiration of the warrants, or until such time as the warrants are no longer determined to be derivative instruments.
	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. 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. Stock-based compensation arrangements with non-employees are recognized at the grant-date fair value and then re-measured at each reporting period. Expense is recognized during the period the related services are rendered.
	Recent Accounting Pronouncements
	In February 2013, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2013-02 which is an amendment to the accounting guidance for the presentation of comprehensive income.  Under the amended guidance, items that are reclassified to net income from accumulated other comprehensive income in the same reporting period require separate disclosure on the face of the financial statements where net income is presented or within the notes to the financial statements. The adoption of this update did not have a material impact on the Company’s financial statements.
	In July 2013, the FASB issued ASU 2013-11 which is an amendment to the accounting guidance on income taxes. This guidance provides clarification on the financial statement presentation of an unrecognized benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. The amendment will be effective for the Company for interim and annual periods beginning after December 15, 2013, with early adoption permitted. The adoption of this standard is not expected to have a material impact on the Company’s financial statements.

Debt

Debt	9 Months Ended
	Sep. 30, 2013
Debt	'
Debt	'
	3. Debt
	Convertible Notes
	In January 2012, the Company issued $6,000,000 of 10% convertible promissory notes for cash.  In September and November 2012, the Company issued the aggregate of $9,700,000 of 10% convertible promissory notes that mature on September 4, 2013 for cash. In connection with the September convertible note financing, the Company and the holders of the January 2012 convertible promissory notes agreed to extend the maturity date of the January 2012 notes to September 4, 2013. In February 2013, these convertible promissory notes, with an outstanding principal of $15,700,000 and accrued interest of $923,092, were amended and then converted into 16,623,092 shares of Series A preferred stock, in accordance with their terms and at their conversion price of $1.00 per share, and following such conversion, the notes were cancelled. The holders of the September convertible promissory notes received the benefit of a deemed conversion price of the September convertible promissory notes that were below the estimated fair value of the Series A convertible preferred stock at the time of their issuance. The fair value of this beneficial conversion feature was estimated to be $287,990. The fair value of this beneficial conversion feature was recorded to debt discount and amortized to interest expense using the effective interest method over the term of the convertible promissory notes. As a result of the conversion of the convertible promissory notes into shares of Series A preferred stock on February 12, 2013, the Company recorded the remaining accretion of the beneficial conversion feature of $229,496 as interest expense during the nine months ended September 30, 2013.
	In April 2008, the Company acquired all of the capital stock of Esperion from Pfizer in exchange for a non-subordinated convertible note in the original principal amount of $5,000,000. This convertible promissory note had a maturity date of April 28, 2018. The note bore interest at 8.931% annually, payable semiannually on June 30 and December 31 by adding such unpaid interest to the principal of the note, which would thereafter accrue interest.  On May 29, 2013 the Company entered into a stock purchase agreement with Pfizer Inc. and sold 6,750,000 shares of Series A-1 preferred stock at a price of $1.1560 per share, which was the fair value at the transaction date. The purchase price was paid through the cancellation of all outstanding indebtedness, including accrued interest, under the Pfizer convertible promissory note, which had an outstanding balance, including accrued interest, of $7,803,000 as of May 29, 2013.  The Series A-1 preferred stock issued in connection with this transaction was subsequently converted into 966,218 shares of common stock upon completion of the IPO on July 1, 2013.

Warrants

Warrants	9 Months Ended
	Sep. 30, 2013
Warrants	'
Warrants	'
	4. Warrants
	In connection with its various financing transactions, the Company issued warrants to purchase shares of preferred stock which had provisions where the underlying issuance was contingently redeemable based on events outside the Company’s control and were recorded as a liability in accordance with ASC 480-10.  Warrants classified as derivative liabilities and were recorded on the Company’s balance sheet at fair value on the date of issuance and were marked-to-market on each subsequent reporting period, with the fair value changes recognized in the statement of operations. The Company estimated the fair values of the warrants at each reporting period using a Black-Scholes option-pricing model, which is based, in part, upon subjective assumptions including but not limited to stock price volatility, the expected life of the warrants, the risk free interest rate and the fair value of the common stock underlying the warrants.  The Company estimates the volatility of its stock based on public company peer group historical volatility that is in line with the expected remaining life of the warrants.  The risk free interest rate is based on the U.S. Treasury zero-coupon bond for a maturity similar to the expected remaining life of the warrants.  The expected remaining life of the warrants is assumed to be equivalent to their remaining contractual term.  In prior periods, a Monte Carlo valuation model was utilized to estimate the fair value of the warrants based on the probability and timing of future financings.
	Upon the closing of the Company’s IPO, all warrants exercisable for 1,940,000 shares of Series A preferred stock, at an exercise price of $1.00 per share, were automatically converted into warrants exercisable for 277,690 shares of common stock, at an exercise price of $6.99 per share. As a result, the Company concluded the warrants outstanding no longer met the criteria to be classified as derivative liabilities and were reclassified to additional paid-in capital at fair value on the date of reclassification.  The 277,690 warrants outstanding as of September 30, 2013 expire in February 2018.

Commitments_and_contingencies

Commitments and contingencies	9 Months Ended
	Sep. 30, 2013
Commitments and contingencies	'
Commitments and contingencies	'
	5. Commitments and contingencies
	In August 2013, the Company entered into the second amendment to the operating lease agreement for its current office and laboratory facility in Plymouth, MI which extended the expiration date of the initial term from October 2, 2013 to April 30, 2014.

Investments

Investments	9 Months Ended
	Sep. 30, 2013
Investments	'
Investments	'
	6. Investments
	The following table summarizes the Company’s cash equivalents and investments:
		September 30, 2013
		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated
									Fair
									Value
	Cash equivalents:
	Money Market Funds	$	13,355,283	$	—	$	—		$	13,355,283
	Investments:
	U.S. treasury notes	6,083,969		2,993		—			6,086,962
	U.S. government agency securities	7,387,319		3,135		(139		)	7,390,315
	Total	$	26,826,571	$	6,128	$	(139	)	$	26,832,560
		December 31, 2012
		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated
									Fair
									Value
	Cash equivalents:
	Money Market Funds	$	6,357,542	—		—			$	6,357,542
	Total	$	6,357,542	$	—	$	—		$	6,357,542
	There were no unrealized gains or losses on investments reclassified from accumulated other comprehensive income to other income (expense) in the Statement of Operations during the nine months ended September 30, 2013.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2013
Fair Value Measurements	'
Fair Value Measurements	'
	7. Fair Value Measurements
	The Company follows accounting guidance that emphasizes that fair value is a market-based measurement, not an entity-specific measurement. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” Fair value measurements are defined on a three level hierarchy:
	Level 1 inputs:	Quoted prices for identical assets or liabilities in active markets;
	Level 2 inputs:	Observable inputs other than Level 1 prices, such as quoted market prices for similar assets or liabilities or other inputs that are observable or can be corroborated by market data; and
	Level 3 inputs:	Unobservable inputs that are supported by little or no market activity and require the reporting entity to develop assumptions that market participants would use when pricing the asset or liability.
	The following table presents the Company’s financial assets and liabilities that have been measured at fair value on a recurring basis:
	Description	Total			Level 1		Level 2		Level 3
	September 30, 2013
	Assets:
	Money market funds	$	13,355,283		$	13,355,283	$	—	$	—
	Available for sale securities:
	U.S. treasury notes	6,086,962			6,086,962		—		—
	U.S. government agency securities	7,390,315			—		7,390,315		—
	Total assets at fair value	$	26,832,560		$	19,442,245	$	7,390,315	$	—
	December 31, 2012
	Assets:
	Money market funds	$	6,357,542		$	6,357,542	$	—	$	—
	Total assets at fair value	$	6,357,542		$	6,357,542	$	—	$	—
	Liabilities:
	Warrants	$	265,323		$	—	$	—	$	265,323
	Total liabilities at fair value	$	265,323		$	—	$	—	$	265,323
	There were no transfers between Levels 1, 2 or 3 during the nine months ended September 30, 2013 or September 30, 2012.
	The following table summarizes the changes in the fair value of the Company’s Level 3 warrant liabilities the nine month period ended September 30, 2013:
		Warrant Liability
	Level 3 Liabilities:
	As of December 31, 2012	$	265,323
	Change in fair value	2,586,865
	Reclassification of warrants liabilities to additional paid-in capital in conjunction with the conversion of the convertible preferred stock into common stock upon the closing of the Company’s IPO	(2,852,188		)
	As of September 30, 2013	$	—
	Fair Value Measurements on a Nonrecurring Basis
	In addition to items that are measured at fair value on a recurring basis, the Company also measures assets held for sale at the lower of its carrying amount or fair value on a nonrecurring basis. During the nine months ended September 30, 2013, the Company recognized an impairment loss of $27,000 based on recent purchase offers. The Company recognized $214,393 of impairment expense related to the assets held for sale in the period from inception through September 30, 2013. The fair value of assets held for sale was estimated using a market approach, considering the estimated fair value for other comparable equipment which are Level 3 inputs.

Convertible_Preferred_Stock_an

Convertible Preferred Stock and Stockholders' Deficit	9 Months Ended
	Sep. 30, 2013
Convertible Preferred Stock and Stockholders' Deficit	'
Convertible Preferred Stock and Stockholders' Deficit	'
	8. Convertible Preferred Stock and Stockholders’ Deficit
	On April 19, 2013, the Company issued and sold an aggregate of 17,000,000 shares of Series A preferred stock at a price of $1.00 per share for proceeds of $16,880,463, which is net of issuance costs of $119,537, to funds affiliated with Longitude Capital and certain existing investors. Each share of Series A preferred stock issued in the financing was convertible into 0.143 shares of common stock as of June 30, 2013.  Upon the closing of the financing, Patrick Enright of Longitude Capital became a member of the board of directors.
	On May 29, 2013, the Company entered into a stock purchase agreement with Pfizer Inc. and issued and sold 6,750,000 shares of Series A-1 preferred stock at a price of $1.1560 per share. The purchase price was paid through the cancellation of all outstanding indebtedness, including accrued interest, under the Pfizer convertible promissory note, which had an aggregate balance, including accrued interest, of $7,803,000 as of May 29, 2013. Each share of Series A-1 preferred stock issued in the agreement was convertible into 0.124 shares of common stock as of June 30, 2013.
	Upon the closing of the Company’s IPO on July 1, 2013, all of the outstanding shares of convertible preferred stock were converted into 9,210,999 shares of common stock. As of September 30, 2013, the Company did not have any convertible preferred stock issued or outstanding.

Stock_Compensation

Stock Compensation	9 Months Ended
	Sep. 30, 2013
Stock Compensation	'
Stock Compensation	'
	9. Stock Compensation
	2013 Stock Option and Incentive Plan
	On June 7, 2013, the Company’s stockholders approved the 2013 Stock Option and Incentive Plan (the 2013 Plan), which became effective on June 25, 2013. The number of shares of stock reserved and available for issuance under the 2013 Plan is the sum of  (i) 1,100,000, plus (ii) 54,129 shares originally reserved under the Company’s 2008 Incentive Stock Option and Restricted Stock Plan (the 2008 Plan) that became available for issuance under the 2013 Plan upon completion of the Company’s initial public offering, plus (iii) the shares underlying any awards granted under the 2008 Plan that are forfeited, canceled, held back upon the exercise of an option or settlement of an award to cover the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without the issuance of stock or otherwise terminated (other than be exercise).  Additionally, on January 1, 2014 and each January 1 thereafter, the number of shares reserved and available for issuance under the 2013 Plan shall be cumulatively increased by two and a half percent of the number of shares issued and outstanding on the immediately preceding December 31 or such lesser number of shares as determined by the plan administrator.
	The following table summarizes the activity relating to the Company’s options to purchase common stock for the nine months ended September 30, 2013:
		Number of		Weighted-Average		Weighted-Average	Aggregate
		Options		Price		Remaining	Intrinsic
				Per Share		Contractual	Value
						Term (Years)
	Outstanding at December 31, 2012	211,500		$	1.43	7.5	$	141,389
	Granted	1,116,549		$	10.34
	Forfeited or expired	(12,212	)	$	2.03
	Exercised	(49,936	)	$	2.47
	Outstanding at September 30, 2013	1,265,901		$	9.24	9.07	$	12,177,504
	The following table summarizes information about the Company’s stock option plan as of September 30, 2013:
		Number of		Weighted-Average		Weighted-Average	Aggregate
		Options		Price		Remaining	Intrinsic
				Per Share		Contractual	Value
						Term (Years)
	Vested and expected to vest at September 30, 2013	1,200,274		$	9.12	9.04	$	11,690,025
	Exercisable at September 30, 2013	559,481		$	2.21	8.34	$	9,317,579
	As of September 30, 2013, there was approximately $6,886,306 of unrecognized compensation cost related to unvested options, adjusted for forfeitures, which will be recognized over a weighted-average period of approximately 3.6 years.

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2013
Income Taxes	'
Income Taxes	'
	10. Income Taxes
	There was no provision for income taxes for the three or nine months ended September 30, 2013 and 2012 because the Company has incurred operating losses since inception. At September 30, 2013, the Company has concluded that it is more likely than not that the Company will not realize the benefit of its deferred tax assets due to its history of losses. Accordingly, the net deferred tax assets have been fully reserved.

Net_Loss_Per_Common_Share

Net Loss Per Common Share	9 Months Ended
	Sep. 30, 2013
Net Loss Per Common Share	'
Net Loss Per Common Share	'
	11. Net Loss Per Common Share
	Basic net loss per share is calculated by dividing net loss by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is computed by dividing net loss by the weighted-average number of common share equivalents outstanding for the period determined using the treasury-stock method. For purposes of this calculation, convertible preferred stock, convertible debt, warrants for preferred stock and stock options are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. Interest expense for convertible debt that is dilutive is added back to net income in the calculation of diluted net loss per share.
	The shares outstanding at the end of the respective periods presented below, after giving effect for the 1-for-6.986 reverse stock split, were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect:
		September 30,	December 31,
		2013	2012
	Convertible preferred stock	—	3,431,865
	Warrants for common stock	277,690	277,690
	Common shares under option	1,265,901	211,500
	Unvested restricted stock	22,190	—
	Convertible debt	—	3,430,723
	Total potential dilutive shares	1,565,781	7,351,778

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2013
Summary of Significant Accounting Policies	'
Cash and Cash Equivalents	'
	Cash and Cash Equivalents
	The Company invests its excess cash in bank deposits, money market accounts, and short-term investments. The Company considers all highly liquid investments with an original maturity of 90 days or less at the time of purchase to be cash equivalents. Cash equivalents are reported at fair value.
Investments	'
	Investments
	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’ deficit. 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 income (expense), net. Realized gains and losses, if any, are determined using the specific identification method and in other income (expense), net. 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.
Concentration of Credit Risk	'
	Concentration of Credit Risk
	Cash, cash equivalents, and marketable securities consist of financial instruments that potentially subject the Company to concentrations of credit risk. The Company has established guidelines for investment of its excess cash and believes the guidelines maintain safety and liquidity through diversification of counterparties and maturities.
Segment Information	'
	Segment Information
	The Company views its operations and manages its business in one operating segment, which is the business of researching, developing and commercializing therapies for the treatment of patients with elevated levels of low-density lipoprotein cholesterol and other cardiometabolic risk factors.
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 that approximate their carrying value.
Property and Equipment, Net	'
	Property and Equipment, Net
	Property and equipment are recorded at cost, less accumulated depreciation. Depreciation is provided using the straight-line method over the estimated useful lives of the respective assets, generally three to ten years. Leasehold improvements are amortized over the lesser of the lease term or the estimated useful lives of the related assets.
Impairment of Long-Lived Assets	'
	Impairment of Long-Lived Assets
	The Company reviews long-lived assets, including property and equipment, 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. Excluding impairment losses recorded on assets held for sale, no other impairment losses have been recorded through September 30, 2013.
Research and Development	'
	Research and Development
	Research and development expenses consist of costs incurred to further the Company’s research and development activities and include salaries and related benefits, costs associated with pre-clinical studies and trials, non-clinical activities (such as toxicology studies), regulatory activities, manufacturing activities to support clinical activities, research-related overhead expenses, and fees paid to external service providers that conduct certain research and development, clinical, and manufacturing activities on behalf of the Company. Research and development costs are expensed as incurred.
In-Process Research and Development	'
	In-Process Research and Development
	In April 2008, the Company acquired certain tangible research and development assets and intellectual property from Pfizer Inc. (Pfizer). As the acquired in-process research and development had not reached technological feasibility and had no alternative future uses in connection with this asset and intellectual property acquisition and the related purchase price allocation, the Company expensed $85,612 as in-process research and development costs in 2008.
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.
Income Taxes	'
	Income Taxes
	The Company utilizes the liability method of accounting for income taxes as required by ASC 740, Income Taxes. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and the tax basis of assets and liabilities and are measured using enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company has incurred operating losses since inception. Accordingly, it is not more likely than not that the Company will realize deferred tax assets and as such, it has recorded a full valuation allowance.
Warrant Liability	'
	Warrant Liability
	The Company accounts for its warrants issued in connection with its various financing transactions based upon the characteristics and provisions of the instrument. Warrants classified as derivative liabilities are recorded on the Company’s balance sheet at their fair value on the date of issuance and are marked-to-market on each subsequent reporting period, with the fair value changes recognized in the statement of operations. The warrants are measured using the Black-Scholes option-pricing model subsequent to the pricing of the Company’s IPO and a Monte Carlo valuation model for previous periods which are based, in part, upon inputs where there is little or no market data, requiring the Company to develop its own independent assumptions. The Company will continue to adjust the liability for changes in the fair value of these warrants until the earlier of the exercise of the warrants, the expiration of the warrants, or until such time as the warrants are no longer determined to be derivative instruments.
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. 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. Stock-based compensation arrangements with non-employees are recognized at the grant-date fair value and then re-measured at each reporting period. Expense is recognized during the period the related services are rendered.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	In February 2013, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2013-02 which is an amendment to the accounting guidance for the presentation of comprehensive income.  Under the amended guidance, items that are reclassified to net income from accumulated other comprehensive income in the same reporting period require separate disclosure on the face of the financial statements where net income is presented or within the notes to the financial statements. The adoption of this update did not have a material impact on the Company’s financial statements.
	In July 2013, the FASB issued ASU 2013-11 which is an amendment to the accounting guidance on income taxes. This guidance provides clarification on the financial statement presentation of an unrecognized benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. The amendment will be effective for the Company for interim and annual periods beginning after December 15, 2013, with early adoption permitted. The adoption of this standard is not expected to have a material impact on the Company’s financial statements.

The_Company_and_Basis_of_Prese1

The Company and Basis of Presentation (Tables)	9 Months Ended
	Sep. 30, 2013
The Company and Basis of Presentation	'
Summary of the Company's capitalization upon closing of its initial public offering	'
	Total common stock issued as of June 30, 2013	396,414
	Conversion of Series A preferred stock into common stock upon closing of IPO	8,244,781
	Conversion of Series A-1 preferred stock into common stock upon closing of IPO	966,218
	Sales of common stock through IPO	5,000,000
	Common stock issued as of July 1, 2013	14,607,413
	Issuance of common stock to underwriters due to exercise of over-allotment	750,000
	Total common stock issued as of July 11, 2013	15,357,413

Investments_Tables

Investments (Tables)	9 Months Ended
	Sep. 30, 2013
Investments	'
Summary of the Company's cash equivalents and investments	'
		September 30, 2013
		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated
									Fair
									Value
	Cash equivalents:
	Money Market Funds	$	13,355,283	$	—	$	—		$	13,355,283
	Investments:
	U.S. treasury notes	6,083,969		2,993		—			6,086,962
	U.S. government agency securities	7,387,319		3,135		(139		)	7,390,315
	Total	$	26,826,571	$	6,128	$	(139	)	$	26,832,560
		December 31, 2012
		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated
									Fair
									Value
	Cash equivalents:
	Money Market Funds	$	6,357,542	—		—			$	6,357,542
	Total	$	6,357,542	$	—	$	—		$	6,357,542

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2013
Fair Value Measurements	'
Schedule of the Company's financial assets and liabilities that have been measured at fair value on a recurring basis	'
	Description	Total			Level 1		Level 2		Level 3
	September 30, 2013
	Assets:
	Money market funds	$	13,355,283		$	13,355,283	$	—	$	—
	Available for sale securities:
	U.S. treasury notes	6,086,962			6,086,962		—		—
	U.S. government agency securities	7,390,315			—		7,390,315		—
	Total assets at fair value	$	26,832,560		$	19,442,245	$	7,390,315	$	—
	December 31, 2012
	Assets:
	Money market funds	$	6,357,542		$	6,357,542	$	—	$	—
	Total assets at fair value	$	6,357,542		$	6,357,542	$	—	$	—
	Liabilities:
	Warrants	$	265,323		$	—	$	—	$	265,323
	Total liabilities at fair value	$	265,323		$	—	$	—	$	265,323
Summary of the changes in the fair value of the Company's Level 3 warrant liabilities	'
		Warrant Liability
	Level 3 Liabilities:
	As of December 31, 2012	$	265,323
	Change in fair value	2,586,865
	Reclassification of warrants liabilities to additional paid-in capital in conjunction with the conversion of the convertible preferred stock into common stock upon the closing of the Company’s IPO	(2,852,188		)
	As of September 30, 2013	$	—

Stock_Compensation_Tables

Stock Compensation (Tables)	9 Months Ended
	Sep. 30, 2013
Stock Compensation	'
Summary of activity relating to the Company's options to purchase common stock	'
		Number of		Weighted-Average		Weighted-Average	Aggregate
		Options		Price		Remaining	Intrinsic
				Per Share		Contractual	Value
						Term (Years)
	Outstanding at December 31, 2012	211,500		$	1.43	7.5	$	141,389
	Granted	1,116,549		$	10.34
	Forfeited or expired	(12,212	)	$	2.03
	Exercised	(49,936	)	$	2.47
	Outstanding at September 30, 2013	1,265,901		$	9.24	9.07	$	12,177,504
Summary of information about the stock option plan	'
		Number of		Weighted-Average		Weighted-Average	Aggregate
		Options		Price		Remaining	Intrinsic
				Per Share		Contractual	Value
						Term (Years)
	Vested and expected to vest at September 30, 2013	1,200,274		$	9.12	9.04	$	11,690,025
	Exercisable at September 30, 2013	559,481		$	2.21	8.34	$	9,317,579

Net_Loss_Per_Common_Share_Tabl

Net Loss Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2013
Net Loss Per Common Share	'
Schedule of anti-dilutive securities excluded from the calculation of diluted net loss per share	'
		September 30,	December 31,
		2013	2012
	Convertible preferred stock	—	3,431,865
	Warrants for common stock	277,690	277,690
	Common shares under option	1,265,901	211,500
	Unvested restricted stock	22,190	—
	Convertible debt	—	3,430,723
	Total potential dilutive shares	1,565,781	7,351,778

The_Company_and_Basis_of_Prese2

The Company and Basis of Presentation (Details) (USD $)

9 Months Ended

68 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

Sep. 30, 2013

Sep. 30, 2013

Jul. 11, 2013

Jul. 02, 2013

Jun. 30, 2013

Jun. 11, 2013

Dec. 31, 2012

Jul. 02, 2013

Jul. 11, 2013

Jul. 02, 2013

Jun. 11, 2013

Jul. 02, 2013

Sep. 30, 2013

Sep. 30, 2013

Jul. 11, 2013

Common stock

Initial Public Offering

Initial Public Offering

Initial Public Offering

Initial Public Offering

Initial Public Offering

Initial Public Offering

Over-allotment option

Warrant

Common stock

Common stock

Convertible preferred stock

Additional paid-in capital

Warrant liabilities

Reverse Stock Split

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Reverse stock split ratio of outstanding common stock

0.1431

'

'

'

'

'

'

'

'

'

0.1431

'

'

'

'

Par value of common stock (in dollars per share)

$0.00

$0.00

'

'

'

$0.00

$0.00

'

'

'

'

'

'

'

'

Initial Public Offering

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common stock, shares issued

15,357,413

15,357,413

15,357,413

14,607,413

396,414

'

346,478

'

'

'

'

'

'

'

'

Original issue price (in dollars per share)

'

'

'

'

'

'

'

'

'

$14

'

'

'

'

$14

Net proceeds from the IPO, including proceeds from the exercise of the underwriters' over-allotment option

$72,367,768

$72,367,768

'

'

'

'

'

'

$72,200,000

'

'

'

'

'

'

Number of shares of convertible preferred stock converted into common stock

'

'

'

'

'

'

'

'

'

'

'

9,210,999

'

'

'

Warrants exercisable into common stock (in shares)

'

'

'

'

'

'

'

277,690

'

'

'

'

'

'

'

Reclassification of convertible preferred stock warrant liability to additional paid-in capital

'

'

'

'

'

'

'

'

'

'

'

'

$2,852,188

($2,852,188)

'

The_Company_and_Basis_of_Prese3

The Company and Basis of Presentation (Details 2)	Sep. 30, 2013	Jul. 11, 2013	Jul. 02, 2013	Jun. 30, 2013	Dec. 31, 2012	Jul. 02, 2013	Jul. 02, 2013	Jul. 02, 2013	Jul. 11, 2013
						Initial Public Offering	Initial Public Offering	Initial Public Offering	Over-allotment option
						Series A preferred stock	Series A-1 preferred stock	Common stock
Movement in Company's capitalization upon closing of initial public offering	'	'	'	'	'	'	'	'	'
Total common stock issued as of the beginning of the period (in shares)	15,357,413	15,357,413	14,607,413	396,414	346,478	'	'	'	'
Conversion of preferred stock into common stock upon closing of IPO (in shares)	'	'	'	'	'	8,244,781	966,218	9,210,999	'
Common stock sold (in shares)	'	'	'	'	'	'	'	5,000,000	750,000
Total common stock issued as of the end of the period (in shares)	15,357,413	15,357,413	14,607,413	396,414	346,478	'	'	'	'

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Details) (USD $)	9 Months Ended	12 Months Ended	68 Months Ended
	Sep. 30, 2013	Dec. 31, 2008	Sep. 30, 2013
	item
Segment Information	'	'	'
Number of operating segments	1	'	'
Impairment of Long-Lived Assets	'	'	'
Other impairment losses	$0	'	'
In-Process Research and Development	'	'	'
Acquired in-process research and development	'	$85,612	$85,612
Property and equipment | Minimum	'	'	'
Property and equipment, net	'	'	'
Estimated useful lives	'3 years	'	'
Property and equipment | Maximum	'	'	'
Property and equipment, net	'	'	'
Estimated useful lives	'10 years	'	'

Debt_Details

Debt (Details) (USD $)

Sep. 30, 2013

Apr. 19, 2013

Dec. 31, 2012

Feb. 28, 2013

Jan. 30, 2012

Nov. 30, 2012

Sep. 30, 2012

Sep. 30, 2013

29-May-13

Apr. 28, 2008

Jul. 02, 2013

29-May-13

Series A preferred stock

Series A preferred stock

Series A preferred stock

10% Convertible promissory notes

Short term convertible notes issued January 2012

Short term convertible notes issued September and November 2012

Short term convertible notes issued September 2012

Short term convertible notes issued September 2012

Pfizer Note

Pfizer Note

Pfizer Note

Pfizer Note

Series A preferred stock

Interest Expense

Series A-1 preferred stock

Series A-1 preferred stock

Debt

'

'

'

'

'

'

'

'

'

'

'

'

Aggregate principal amount

'

'

'

$15,700,000

$6,000,000

$9,700,000

'

'

'

$5,000,000

'

'

Interest rate (as a percent)

'

'

'

'

10.00%

10.00%

'

'

'

8.93%

'

'

Accrued interest

'

'

'

923,092

'

'

'

'

'

'

'

'

Conversion of convertible promissory notes into Series A preferred stock (in shares)

'

'

'

16,623,092

'

'

'

'

'

'

'

'

Conversion price (in dollars per share)

'

'

'

$1

'

'

'

'

'

'

'

'

Outstanding principal amount

'

'

'

'

'

'

'

'

7,803,000

'

'

'

Fair value of beneficial conversion feature

'

'

'

'

'

'

287,990

'

'

'

'

'

Discount on short term convertible notes

'

'

'

'

'

'

'

($229,496)

'

'

'

'

Preferred stock, shares issued

0

17,000,000

23,975,000

'

'

'

'

'

'

'

'

6,750,000

Share price of preferred stock (in dollars per share)

'

$1

'

'

'

'

'

'

'

'

'

$1.16

Number of shares of preferred stock converted into shares of common stock

'

'

'

'

'

'

'

'

'

'

966,218

'

Warrants_Details

Warrants (Details) (USD $)	Sep. 30, 2013	Jul. 02, 2013	Jul. 02, 2013
	Warrant	Series A preferred stock warrant	Common stock
			Warrant
Warrants	'	'	'
Warrants exercisable into stock (in shares)	'	1,940,000	277,690
Exercise price (in dollars per share)	'	$1	'
Share price of common stock (in dollars per share)	'	'	$6.99
Number of shares of common stock to be purchased against outstanding warrants	277,690	'	'

Investments_Details

Investments (Details) (USD $)	3 Months Ended		9 Months Ended		68 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Dec. 31, 2012
Cash equivalents and investments	'	'	'	'	'	'
Gross Unrealized Gains	$6,128	'	$6,128	'	$6,128	'
Gross Unrealized Losses	-139	'	-139	'	-139	'
Investments, Estimated Fair Value	13,477,277	'	13,477,277	'	13,477,277	'
Total, Amortized Cost	71,895,828	'	71,895,828	'	71,895,828	6,511,521
Total, Estimated Fair Value	26,832,560	'	26,832,560	'	26,832,560	6,357,542
Unrealized gains or losses on investments	168,389	401	147,440	2,354	228,854	'
Reclassification out of accumulated other comprehensive income	'	'	'	'	'	'
Cash equivalents and investments	'	'	'	'	'	'
Unrealized gains or losses on investments	'	'	0	'	'	'
U.S. treasury notes	'	'	'	'	'	'
Cash equivalents and investments	'	'	'	'	'	'
Investments, Amortized Cost	6,083,969	'	6,083,969	'	6,083,969	'
Gross Unrealized Gains	2,993	'	2,993	'	2,993	'
Investments, Estimated Fair Value	6,086,962	'	6,086,962	'	6,086,962	'
U.S. government agency securities	'	'	'	'	'	'
Cash equivalents and investments	'	'	'	'	'	'
Investments, Amortized Cost	7,387,319	'	7,387,319	'	7,387,319	'
Gross Unrealized Gains	3,135	'	3,135	'	3,135	'
Gross Unrealized Losses	-139	'	-139	'	-139	'
Investments, Estimated Fair Value	7,390,315	'	7,390,315	'	7,390,315	'
Money Market Funds	'	'	'	'	'	'
Cash equivalents and investments	'	'	'	'	'	'
Cash equivalents, Estimated Fair Value	$13,355,283	'	$13,355,283	'	$13,355,283	$6,357,542

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Assets:	'	'	'
Available for sale securities	$13,477,277	'	'
Total, Estimated Fair Value	26,832,560	'	6,357,542
Liabilities:	'	'	'
Warrants	'	'	265,323
Transfer of assets between levels	0	0	'
Transfer of liabilities between levels	0	0	'
U.S. treasury notes	'	'	'
Assets:	'	'	'
Available for sale securities	6,086,962	'	'
U.S. government agency securities	'	'	'
Assets:	'	'	'
Available for sale securities	7,390,315	'	'
Recurring fair value measurement | Level 1	'	'	'
Assets:	'	'	'
Money market fund	13,355,283	'	6,357,542
Total, Estimated Fair Value	19,442,245	'	6,357,542
Recurring fair value measurement | Level 1 | U.S. treasury notes	'	'	'
Assets:	'	'	'
Available for sale securities	6,086,962	'	'
Recurring fair value measurement | Level 2	'	'	'
Assets:	'	'	'
Total, Estimated Fair Value	7,390,315	'	'
Recurring fair value measurement | Level 2 | U.S. government agency securities	'	'	'
Assets:	'	'	'
Available for sale securities	7,390,315	'	'
Recurring fair value measurement | Level 3	'	'	'
Liabilities:	'	'	'
Warrants	'	'	265,323
Total liabilities at fair value	'	'	265,323
Recurring fair value measurement | Total	'	'	'
Assets:	'	'	'
Money market fund	13,355,283	'	6,357,542
Total, Estimated Fair Value	26,832,560	'	6,357,542
Liabilities:	'	'	'
Warrants	'	'	265,323
Total liabilities at fair value	'	'	265,323
Recurring fair value measurement | Total | U.S. treasury notes	'	'	'
Assets:	'	'	'
Available for sale securities	6,086,962	'	'
Recurring fair value measurement | Total | U.S. government agency securities	'	'	'
Assets:	'	'	'
Available for sale securities	$7,390,315	'	'

Fair_Value_Measurements_Detail1

Fair Value Measurements (Details 2) (Warrant Liability, USD $)	9 Months Ended
	Sep. 30, 2013
Warrant Liability	'
Changes in the fair value of Level 3 warrant liabilities	'
Level 3 liabilities beginning balance	$265,323
Change in fair value	2,586,865
Reclassification of warrants liabilities to additional paid-in capital in conjunction with the conversion of the convertible preferred stock into common stock upon the closing of the Company's IPO	($2,852,188)

Fair_Value_Measurements_Detail2

Fair Value Measurements (Details 3) (Nonrecurring fair value measurement, USD $)	9 Months Ended	68 Months Ended
	Sep. 30, 2013	Sep. 30, 2013
Nonrecurring fair value measurement	'	'
Fair Value Measurements on a Nonrecurring Basis	'	'
Impairment loss related to the assets held for sale	$27,000	$214,393

Convertible_Preferred_Stock_an1

Convertible Preferred Stock and Stockholders' Deficit (Details) (USD $)	9 Months Ended	68 Months Ended		0 Months Ended			0 Months Ended		0 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	29-May-13	Apr. 19, 2013	Sep. 30, 2013	Dec. 31, 2012	Jul. 02, 2013	29-May-13	Jul. 02, 2013	Jul. 02, 2013	Jul. 02, 2013
			Pfizer note	Series A preferred stock	Series A preferred stock	Series A preferred stock	Series A-1 preferred stock	Series A-1 preferred stock	IPO	IPO	IPO
							Pfizer note	Pfizer note	Common stock	Series A preferred stock	Series A-1 preferred stock
Convertible preferred stock and stockholders' deficit	'	'	'	'	'	'	'	'	'	'	'
Preferred stock, shares issued	'	'	'	17,000,000	0	23,975,000	'	6,750,000	'	'	'
Share price of preferred stock (in dollars per share)	'	'	'	$1	'	'	'	$1.16	'	'	'
Proceeds from issuance of preferred stock, net of issuance costs	$16,824,235	$40,799,235	'	$16,880,463	'	'	'	'	'	'	'
Stock issuance costs	'	'	'	119,537	'	'	'	'	'	'	'
Conversion rate	'	'	'	0.143	'	'	'	0.124	'	'	'
Outstanding principal amount	'	'	$7,803,000	'	'	'	'	'	'	'	'
Number of shares of convertible preferred stock converted into common stock	'	'	'	'	'	'	966,218	'	9,210,999	8,244,781	966,218

Stock_Compensation_Details

Stock Compensation (Details) (USD $)	9 Months Ended	12 Months Ended	0 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Jun. 25, 2013	Jun. 25, 2013
			2013 Plan	2008 Plan
Stock compensation	'	'	'	'
Shares reserved and approved for issuance	'	'	1,100,000	'
Shares reserved under previous plan and subsequently transferred to new plan	'	'	54,129	-54,129
Percentage of increase in the number of shares reserved and available for issuance	'	'	2.50%	'
Number of Options	'	'	'	'
Outstanding at the beginning of period (in shares)	211,500	'	'	'
Granted (in shares)	1,116,549	'	'	'
Forfeited or expired (in shares)	-12,212	'	'	'
Exercised (in shares)	-49,936	'	'	'
Outstanding at the end of the period (in shares)	1,265,901	211,500	'	'
Weighted-Average Price Per Share	'	'	'	'
Outstanding at the beginning of period (in dollars per share)	$1.43	'	'	'
Granted (in dollars per share)	$10.34	'	'	'
Forfeited or expired (in dollars per share)	$2.03	'	'	'
Exercised (in dollars per share)	$2.47	'	'	'
Outstanding at the end of the period (in dollars per share)	$9.24	$1.43	'	'
Weighted-Average Remaining Contractual Term (Years)	'	'	'	'
Outstanding at the end of the period	'9 years 25 days	'7 years 6 months	'	'
Aggregate Intrinsic Value	'	'	'	'
Outstanding at the end of the period (in dollars)	$12,177,504	$141,389	'	'
Information about the stock option plan	'	'	'	'
Number of Options, vested and expected to vest (in shares)	1,200,274	'	'	'
Number of Options, exercisable (in shares)	559,481	'	'	'
Weighted-Average Price Per Share, vested and expected to vest (in dollars per share)	$9.12	'	'	'
Weighted-Average Price Per Share, exercisable (in dollars per share)	$2.21	'	'	'
Weighted-Average Remaining Contractual Term, vested and expected to vest	'9 years 14 days	'	'	'
Weighted-Average Remaining Contractual Term, exercisable	'8 years 4 months 2 days	'	'	'
Aggregate Intrinsic Value, vested and expected to vest (in dollars)	11,690,025	'	'	'
Aggregate Intrinsic Value, exercisable (in dollars)	9,317,579	'	'	'
Additional disclosures	'	'	'	'
Unrecognized compensation cost (in dollars)	$6,886,306	'	'	'
Weighted-average period over which remaining unrecognized compensation cost will be recognized	'3 years 7 months 6 days	'	'	'

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Taxes	'	'	'	'
Provision for income taxes	$0	$0	$0	$0

Net_Loss_Per_Common_Share_Deta

Net Loss Per Common Share (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Net Loss Per Common Share	'	'
Reverse stock split	0.1431	'
Net Loss Per Common Share	'	'
Total potential dilutive shares	1,565,781	7,351,778
Convertible preferred stock	'	'
Net Loss Per Common Share	'	'
Total potential dilutive shares	'	3,431,865
Warrants for common stock	'	'
Net Loss Per Common Share	'	'
Total potential dilutive shares	277,690	277,690
Common shares under option	'	'
Net Loss Per Common Share	'	'
Total potential dilutive shares	1,265,901	211,500
Unvested restricted stock	'	'
Net Loss Per Common Share	'	'
Total potential dilutive shares	22,190	'
Convertible debt	'	'
Net Loss Per Common Share	'	'
Total potential dilutive shares	'	3,430,723