Loxo Oncology (LOXO) Inactive 10-Q14 Nov 142014 Q3 Quarterly reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 30, 2014	Nov. 11, 2014
Document and Entity Information	'	'
Entity Registrant Name	'Loxo Oncology, Inc.	'
Entity Central Index Key	'0001581720	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-14	'
Amendment Flag	'false	'
Current Fiscal Year End Date	'--12-31	'
Entity Current Reporting Status	'No	'
Entity Filer Category	'Smaller Reporting Company	'
Entity Common Stock, Shares Outstanding	'	16,634,063
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'

Condensed_Balance_Sheets

Condensed Balance Sheets (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Current assets:	'	'
Cash and cash equivalents	$118,621	$14,994
Prepaid expenses with related party and other current assets	1,415	17
Total current assets	120,036	15,011
Property and equipment	13	'
Security deposit	23	11
Total assets	120,072	15,022
Current liabilities:	'	'
Accounts payable	207	221
Accrued expenses	520	189
Total liabilities	727	410
Commitments and contingencies	'	'
Redeemable convertible preferred stock	'	24,843
Stockholders' (deficit) equity:	'	'
Preferred stock, $0.0001 par value, 5,000,000 shares authorized, no shares issued and outstanding at December 31, 2013 and September 30, 2014	'	'
Common stock, $0.0001 par value; 9,375,000 and 125,000,000 shares authorized at December 31, 2013 and September 30, 2014, respectively; 452,896 and 16,644,229 shares issued and 452,896 and 16,634,063 outstanding at December 31, 2013 and September 30, 2014, respectively	2	'
Additional paid-in capital	143,183	59
Accumulated deficit	-23,840	-10,290
Total stockholders' (deficit) equity	119,345	-10,231
Total liabilities, redeemable convertible preferred stock and stockholders' (deficit) equity	120,072	15,022
Redeemable convertible Series A preferred stock	'	'
Current liabilities:	'	'
Redeemable convertible preferred stock	'	17,799
Redeemable convertible Series A-1 preferred stock	'	'
Current liabilities:	'	'
Redeemable convertible preferred stock	'	$7,044

Condensed_Balance_Sheets_Paren

Condensed Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
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	125,000,000	9,375,000
Common stock, shares issued	16,644,229	452,896
Common stock, shares outstanding	16,634,063	452,896
Redeemable convertible Series A preferred stock	'	'
Redeemable convertible preferred stock, par value (in dollars per share)	$0.00	$0.00
Redeemable convertible preferred stock, shares authorized	0	5,156,250
Redeemable convertible preferred stock, shares issued	0	2,812,497
Redeemable convertible preferred stock, shares outstanding	0	2,812,497
Redeemable convertible preferred stock, liquidation preference (in dollars)	$0	$18,000
Redeemable convertible Series A-1 preferred stock	'	'
Redeemable convertible preferred stock, par value (in dollars per share)	$0.00	$0.00
Redeemable convertible preferred stock, shares authorized	0	500,704
Redeemable convertible preferred stock, shares issued	0	500,704
Redeemable convertible preferred stock, shares outstanding	0	500,704
Redeemable convertible preferred stock, liquidation preference (in dollars)	$0	$12,000
Redeemable convertible Series B preferred stock	'	'
Redeemable convertible preferred stock, shares outstanding	0	'

Condensed_Statements_of_Operat

Condensed Statements of Operations (USD $)	3 Months Ended		5 Months Ended	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2014
Operating expenses:	'	'	'	'
Research and development with related party	$2,413	$8,149	$8,202	$5,405
Research and development	2,623	37	43	4,412
General and administrative	1,707	159	190	3,733
Total operating expenses and net loss	-6,743	-8,345	-8,435	-13,550
Accretion of redeemable convertible preferred stock	-6	'	'	-34
Net loss attributable to common stockholders	($6,749)	($8,345)	($8,435)	($13,584)
Per share information	'	'	'	'
Net loss per share of common stock, basic and diluted (in dollars per share)	($0.68)	($45.20)	($71.52)	($3.87)
Weighted average shares outstanding, basic and diluted	9,947,321	184,605	117,942	3,510,170

Condensed_Statements_of_Redeem

Condensed Statements of Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity (USD $)	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Redeemable convertible Series A preferred stock	Redeemable convertible Series A-1 preferred stock	Redeemable convertible Series B preferred stock	Series A shares	Series B shares
In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Redeemable convertible Series A preferred stock	Redeemable convertible Series A-1 preferred stock	Redeemable convertible Series B preferred stock	Series A shares	Series B shares
Balance at Dec. 31, 2013	($10,231)	'	$59	($10,290)	'	'	'	'	'
Balance at Dec. 31, 2013	24,843	'	'	'	17,799	7,044	'	'	'
Balance (in shares) at Dec. 31, 2013	'	452,896	'	'	'	'	'	'	'
Balance (in shares) at Dec. 31, 2013	'	'	'	'	2,812,497	500,704	'	'	'
Changes in Redeemable Securities	'	'	'	'	'	'	'	'	'
Issuance of redeemable convertible preferred stock	'	'	'	'	'	'	'	15,000	28,178
Issuance of redeemable convertible preferred stock (in shares)	'	6,134,307	'	'	'	'	'	2,343,753	3,166,233
Accretion of redeemable convertible preferred stock to redemption value	34	'	'	'	26	'	8	'	'
Conversion of redeemable convertible preferred stock into common stock	-68,055	-1	-68,054	'	-32,825	-7,044	-28,186	'	'
Conversion of redeemable convertible preferred stock into common stock (in shares)	'	9,932,042	'	'	-5,156,250	-500,704	-3,166,233	'	'
Changes Stockholders' Equity	'	'	'	'	'	'	'	'	'
Issuance of common stock due to exercise of vested options	167	'	167	'	'	'	'	'	'
Issuance of common stock due to exercise of vested options (in shares)	'	114,818	'	'	'	'	'	'	'
Accretion of redeemable convertible preferred stock to redemption value	-34	'	-34	'	'	'	'	'	'
Conversion of redeemable convertible preferred stock into common stock	68,055	1	68,054	'	32,825	7,044	28,186	'	'
Issuance of common stock in connection with initial public offering and private placement, net of offering costs	72,366	1	72,365	'	'	'	'	'	'
Issuance of common stock in connection with initial public offering and private placement, net of offering costs (in shares)	'	6,134,307	'	'	'	'	'	2,343,753	3,166,233
Stock-based compensation expense	2,572	'	2,572	'	'	'	'	'	'
Net loss	-13,550	'	'	-13,550	'	'	'	'	'
Balance at Sep. 30, 2014	$119,345	$2	$143,183	($23,840)	'	'	'	'	'
Balance (in shares) at Sep. 30, 2014	'	16,634,063	'	'	'	'	'	'	'
Balance (in shares) at Sep. 30, 2014	'	'	'	'	0	0	0	'	'

Condensed_Statements_of_Redeem1

Condensed Statements of Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity (Parenthetical) (USD $)	Mar. 31, 2014	Jun. 30, 2014	Apr. 30, 2014
	Redeemable convertible Series A preferred stock	Redeemable convertible Series B preferred stock	Redeemable convertible Series B preferred stock
Issuance of redeemable convertible preferred stock, issue price (in dollars per share)	$6.40	$8.97	$8.97

Condensed_Statements_of_Cash_F

Condensed Statements of Cash Flows (USD $)	5 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2014
Operating activities:	'	'
Net loss	($8,435)	($13,550)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'
Depreciation expense	0	1
Issuance of redeemable convertible preferred stock in connection with collaboration agreement	7,044	'
Stock-based compensation	'	2,572
Changes in operating assets and liabilities:	'	'
Prepaid expenses and other assets	-375	-1,230
Security deposits	'	-12
Accounts payable	66	-14
Accrued expenses	203	163
Net cash used in operating activities	-1,497	-12,070
Investing activities:	'	'
Purchase of property	'	-14
Net cash used in investing activities	0	-14
Financing activities:	'	'
Proceeds from issuance of redeemable convertible preferred stock, net	17,787	43,178
Proceeds from the issuance of common stock	1	74,331
Payment of deferred financing fees	'	-1,798
Net cash provided by financing activities	17,788	115,711
Net increase in cash and cash equivalents	16,291	103,627
Cash and cash equivalents-beginning of period	'	14,994
Cash and cash equivalents-end of period	16,291	118,621
Supplemental schedule of noncash activities:	'	'
Prepayments of non-refundable fees to contract service organizations	'	168
Noncash financing activities:	'	'
Conversion of redeemable convertible preferred stock into common stock	'	$68,055

Organization_and_Description_o

Organization and Description of the Business	9 Months Ended
Organization and Description of the Business	Sep. 30, 2014
Organization and Description of the Business	'
Organization and Description of the Business	'
	1. Organization and Description of the Business

	Loxo Oncology, Inc. (the “Company”) was incorporated on May 9, 2013 in the State of Delaware. The Company develops targeted small molecule therapeutics for the treatment of cancer in genetically defined patient populations. The Company’s development approach translates key scientific insights relating to the oncogenic drivers of cancer into drugs that are potent and highly selective for their intended targets. Such drugs typically achieve high target engagement, which has been correlated with improved tumor response. The Company is also building a pipeline of additional product candidates targeting cancers driven by genetic alterations. The Company operates in one segment and has its principal office in Stamford, Connecticut.

	Initial Public Offering

	On July 31, 2014, the Company’s registration statements on Form S-1 (File Nos. 333-197123 and 333-197779) relating to its initial public offering of its common stock were declared effective by the Securities and Exchange Commission (“SEC”). The shares began trading on The NASDAQ Global Select Market on August 1, 2014. The initial public offering closed on August 6, 2014, and 5,261,538 shares of common stock were sold at an initial public offering price of $13.00 per share, for aggregate gross proceeds to the Company of $68.4 million. Concurrent with the close of the offering, New Enterprise Associates 14, L.P., or NEA, an existing stockholder, purchased 230,769 shares of common stock at the initial public offering price in a private placement and the Company received gross proceeds of $3.0 million. In addition, upon the closing of the initial public offering, all of the Company’s outstanding convertible preferred stock was converted into an aggregate total of 9,932,042 shares of common stock.

	On August 29, 2014, the underwriters of the Company’s initial public offering gave notification that they would partially exercise the over-allotment option granted to them and on September 4, 2014, 642,000 additional shares of common stock were sold on the Company’s behalf at the initial public offering price of $13.00 per share, for aggregate gross proceeds of approximately $8.3 million.

	The Company paid to the underwriters underwriting discounts and commissions of approximately $5.6 million in connection with the offering, including the private placement and over-allotment. In addition, the Company incurred expenses of approximately $1.7 million in connection with the offering. Thus, the net offering proceeds to the Company, after deducting underwriting discounts and commissions and offering expenses, were approximately $72.4 million.

	Stock Splits

	In July 2013, the Company’s Board of Directors (the “Board”) and stockholders approved a 2.07 to 1 reverse stock split of the Company’s common stock. The reverse stock split became effective on July 2, 2013. Subsequently, in July 2014, the Board and stockholders approved a 1.5625-for-1 forward stock split of the Company’s common stock. The forward stock split became effective on July 21, 2014. All share and per share amounts in the financial statements and notes thereto have been adjusted to give effect to this reverse stock split.

	Liquidity

	At September 30, 2014, the Company had working capital of $119.3 million, an accumulated deficit of $23.8 million, and cash and cash equivalents of $118.6 million. Upon consummation of its initial public offering and the concurrent private placement on August 6, 2014, and the over-allotment exercise on September 5, 2014, the Company received cash proceeds, net of underwriting discounts and commissions, and initial public offering costs of approximately $72.4 million. The Company has not generated any product revenues and has not achieved profitable operations. There is no assurance that profitable operations will ever be achieved, and, if achieved, could be sustained on a continuing basis. In addition, development activities, clinical and pre-clinical testing, and commercialization of the Company’s products will require significant additional financing.

	The Company believes that its existing cash and cash equivalents, in conjunction with the proceeds received in connection with its initial public offering and concurrent private placement in August 2014, will be sufficient to enable the Company to continue as a going concern for a reasonable period of time beyond September 30, 2014. However, the Company will need to secure additional funding in the future, from one or more equity or debt financings, collaborations, or other sources, in order to carry out all of its planned research and development activities. If the Company is unable to obtain additional financing or generate license or product revenue, the lack of liquidity could have a material adverse effect on the Company’s future prospects.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 2014
Summary of Significant Accounting Policies	'
Summary of Significant Accounting Policies	'
	2. Summary of Significant Accounting Policies

	Basis of Presentation

	The accompanying financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”).

	Unaudited Interim Financial Information

	The accompanying balance sheet as of December 31, 2013, was derived from the Company’s audited financial statements included in Form S-1 filed on July 30, 2014 with the SEC that was declared effective on July 31, 2014.

	The accompanying balance sheet as of September 30, 2014, the statements of operations for the three and nine months ended September 30, 2014, the three months ended September 30, 2013 and the period from May 9, 2013 (Date of Inception) to September 30, 2013, the statements of redeemable convertible preferred stock and stockholders’ (deficit) equity for the nine months ended September 30, 2014 and the statements of cash flows for the nine months ended September 30, 2014 and the period from May 9, 2013 (Date of Inception) to September 30, 2013 are unaudited. The interim unaudited financial statements have been prepared on the same basis as the annual audited financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2014 and the results of its operations for the three and nine months ended September 30, 2014, the three months ended September 30, 2013 and the period from May 9, 2013 (Date of inception) to September 30, 2013, and its cash flows for the nine months ended September 30, 2014 and the period from May 9, 2013 (Date of inception) to September 30, 2013. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2014, the three months ended September 30, 2013 and for the period from May 9, 2013 (Date of inception) to September 30, 2013 are unaudited. The results for the nine months ended September 30, 2014 are not necessarily indicative of results to be expected for the year ending December 31, 2014, any other interim periods or any future year or period. These unaudited financial statements should be read in conjunction with the audited financial statements and the notes thereto for the year ended December 31, 2013 included in the Company’s Form S-1 filed July 30, 2014 with the SEC.

	Significant Accounting Policies

	The Company’s significant accounting policies are disclosed in the audited financial statements for the period ended December 31, 2013 included in the Company’s Form S-1 filed on July 30, 2014 with the SEC. Since the date of such financial statements, there have been no changes to the Company’s significant accounting policies, other than those detailed below.

	Property and Equipment

	Property and equipment are depreciated using the straight-line method over the estimated useful lives of the assets, which are generally three to five years. Maintenance and repairs are expensed as incurred. Upon disposal, retirement, or sale, the related cost and accumulated depreciation is removed from the accounts and any resulting gain or loss is included in the results of operations. The Company recognized depreciation expense of $1,000 during the three and nine months ended September 30, 2014. There was no depreciation during the three months ended September 30, 2013 and during the period from May 9, 2013 (Date of Inception) to September 30, 2013.

	Research and Development Expenses

	Research and development costs are charged to expense as incurred. These costs include, but are not limited to, employee-related expenses, including salaries, benefits, stock-based compensation and travel as well as expenses related to third-party collaborations and contract research agreements; expenses incurred under agreements with contract research organizations and investigative sites that conduct preclinical studies; the cost of acquiring, developing and manufacturing clinical trial materials; facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, insurance and other supplies; and costs associated with preclinical activities and regulatory operations.

	Costs for certain development activities, such as preclinical studies, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, preclinical site activations, or information provided to the Company by its vendors with respect to their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the consolidated financial statements as prepaid or accrued research and development expense, as the case may be.

	Recent Accounting Pronouncements

	On August 27, 2014, the FASB issued ASU 2014-15 Presentation of Financial Statement-Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern, which provides guidance on determining when and how reporting entities must disclose going-concern uncertainties in their financial statements. The new standard requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date of issuance of the entity’s financial statements (or within one year after the date on which the financial statements are available to be issued, when applicable). Further, an entity must provide certain disclosures if there is “substantial doubt about the entity’s ability to continue as a going concern.” The FASB believes that requiring management to perform the assessment will enhance the timeliness, clarity, and consistency of related disclosures and improve convergence with IFRSs (which emphasize management’s responsibility for performing the going-concern assessment). However, the time horizon for the assessment (look-forward period) and the disclosure thresholds under U.S. GAAP and IFRSs will continue to differ. The Company does not anticipate that the adoption of this standard will have a material impact on its financial statements.

	On June 10, 2014, the FASB issued ASU No. 2014-10, Development Stage Entities (Topic 915): Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 810, Consolidation. The guidance is intended to reduce the overall cost and complexity associated with financial reporting for development stage entities without reducing the availability of relevant information. The Board also believes the changes will simplify the consolidation accounting guidance by removing the differential accounting requirements for development stage entities. As a result of these changes, there no longer will be any accounting or reporting differences in GAAP between development stage entities and other operating entities. For organizations defined as public business entities the presentation and disclosure requirements in Topic 915 will no longer be required starting with the first annual period beginning after December 15, 2014, including interim periods therein. Early application is permitted for any annual reporting period or interim period for which the entity’s financial statements have not yet been issued (public business entities) or made available for issuance (other entities). The Company early adopted this guidance during the three months ended June 30, 2014 and, as a result, the Company no longer presents inception-to-date information about the statements of operations, cash flows, and stockholders’ (deficit) equity.

	In June 2014, the FASB issued ASU No. 2014-12, Compensation - Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide that a Performance Target Could be Achieved after the Requisite Service Period, (“ASU 2014-12”). ASU 2014-12 requires that a performance target that affects vesting, and that could be achieved after the requisite service period, be treated as a performance condition. As such, the performance target should not be reflected in estimating the grant date fair value of the award. This update further clarifies that compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the period(s) for which the requisite service has already been rendered. The Company does not anticipate that the adoption of this standard will have a material impact on its financial statements.

	Reclassifications

	Certain reclassifications were made to prior period amounts to correct the previous presentation. During the nine months ended September 30, 2014, certain expenses that had been previously classified as general and administrative were reclassified into research and development. The Company reclassified $56 and $167 of expenses related to the three months ended March 31, 2014 and June 30, 2014, respectively.

Net_Loss_Per_Common_Share

Net Loss Per Common Share	9 Months Ended
Net Loss Per Common Share	Sep. 30, 2014
Net Loss Per Common Share	'
Net Loss Per Common Share	'
	3. Net Loss Per Common Share

	The following table sets forth the computation of basic and diluted net loss per share for the periods indicated (in thousands, except share and per share data):

								Period From
		Three Months			Three Months			May 9, 2013			Nine Months
		Ended			Ended			(Date of Inception)			Ended
		September 30,			September 30,			to September 30,			September 30,
		2013			2014			2013			2014

	Basic and diluted net loss per common share calculation:
	Net loss	$	(8,345	)	$	(6,743	)	$	(8,435	)	$	(13,550	)
	Accretion of redeemable convertible preferred stock	—			(6		)	—			(34		)
	Net loss attributable to common stockholders	$	(8,345	)	$	(6,749	)	$	(8,435	)	$	(13,584	)
	Weighted average common shares outstanding	184,605			9,947,321			117,942			3,510,170
	Net loss per share of common stock—basic and diluted	$	(45.20	)	$	(0.68	)	$	(71.52	)	$	(3.87	)

	The following outstanding securities at September 30, 2013 and 2014 have been excluded from the computation of diluted weighted average shares outstanding, as they would have been anti-dilutive:

		2013		2014
	Redeemable convertible preferred stock	3,313,201		—
	Unvested restricted stock	264,190		187,134
	Stock options	—		1,507,905
		3,577,391		1,695,039

Accrued_Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2014
Accrued Expenses	'
Accrued Expenses	'
	4. Accrued Expenses

	Accrued expenses consisted of the following (in thousands):

		December 31,		September 30,
		2013		2014
	Research and development expenses	$	81	$	239
	General and administrative expenses	108		244
	Share repurchase obligation	—		37
		$	189	$	520

Capital_Stock_Redeemable_Conve

Capital Stock, Redeemable Convertible Preferred Stock, and Stockholders' (Deficit) Equity	9 Months Ended
	Sep. 30, 2014
Capital Stock, Redeemable Convertible Preferred Stock, and Stockholders' (Deficit) Equity	'
Capital Stock, Redeemable Convertible Preferred Stock, and Stockholders' (Deficit) Equity	'
	5. Capital Stock, Redeemable Convertible Preferred Stock, and Stockholders’ (Deficit) Equity

	Capitalization

	As of December 31, 2013, the Company’s amended and restated certificate of incorporation reflected the following authorized shares: 15,031,954 shares of capital stock, consisting of 9,375,000 shares of common stock, par value of $0.0001 per share, and 5,656,954 shares of preferred stock, par value of $0.0001 per share of which (i) 5,156,250 shares are designated Series A Redeemable Convertible Preferred Stock (“Series A”) and (ii) 500,704 shares are designated Series A-1 Redeemable Convertible Preferred Stock (“Series A-1”).

	On July 21, 2014, the Company amended and restated its certificate of incorporation to reflect the following authorized share increases: 31,010,691 shares of capital stock, consisting of 22,187,500 shares of common stock, par value of $0.0001 per share, and 8,823,191 shares of preferred stock, par value of $0.0001 per share of which (i) 5,156,250 shares are designated Series A Redeemable Convertible Preferred Stock, (ii) 500,704 shares are designated Series A-1 Redeemable Convertible Preferred Stock and (iii) 3,166,237 shares are designated Series B Redeemable Convertible Preferred Stock.

	On August 7, 2014, in connection with its initial public offering, the Company amended and restated its certificate of incorporation to reflect the following authorized share increases: 130,000,000 shares of capital stock, consisting of 125,000,000 shares of common stock, par value $0.0001 per share and 5,000,000 shares of preferred stock, par value $0.0001 per share.

	On June 28, 2013 and July 3, 2013, the Company issued 452,896 shares of common stock to its co-founders. The shares of common stock issued to two of these co-founders, aggregating 264,190 shares, were subject to vesting pursuant to restricted stock agreements, with 25% of such shares vesting on July 3, 2014 and the remaining 75% vesting in equal monthly installments over a three-year period thereafter. The estimated grant-date fair value of these restricted shares was de minimis.

	On July 3, 2013, the Company entered into a stock purchase agreement, which was subsequently amended on September 19, 2013, pursuant to which the Company agreed to sell to certain investors, upon the satisfaction of certain conditions, up to 2,812,497 shares of Series A. The initial closing occurred on July 3, 2013 and 1,562,500 shares of Series A were issued. The remaining 1,249,997 shares were issued on September 19, 2013. Upon completing the July and September closings, the Company received net proceeds of approximately $17.8 million. Additionally on July 3, 2013, the Company issued 500,704 shares, with an estimated fair value of approximately $7.0 million, of Series A-1 to Array in connection with entering into a collaboration agreement (see Note 6). The estimated fair value of these shares has been recognized as research and development expense-related party in the accompanying unaudited condensed statements of operations.

	On February 28, 2014, the Company filed with the United States Food and Drug Administration an Investigational New Drug Application for a tyrosine kinase inhibitor targeted to the TRK family of receptors. As a result and in accordance with the provisions of the stock purchase agreement entered into on July 3, 2013, the Company issued 2,343,753 shares of Series A at a price of $6.40 per share and received net proceeds of $15.0 million on March 18, 2014.

	On April 24, 2014 and June 24, 2014, the Company entered into stock purchase agreements pursuant to which the Company agreed to sell 2,664,343 and 501,890 shares, respectively, of Series B, $0.0001 par value, at a purchase price of $8.9661 per share. Upon completing the April and June offerings, the Company received gross proceeds of approximately $28.4 million.

	As previously discussed in Note 1, the Company completed its initial public offering in August 2014. As part of that offering, all of the Company’s outstanding convertible preferred stock was converted into an aggregate total of 9,932,042 shares of common stock.

	2013 Equity Incentive Plan

	Effective July 2, 2013, the Company adopted the 2013 Equity Incentive Plan, which was amended in November 2013 (the 2013 “Plan”). The 2013 Plan provides for the granting of incentive stock options, non-statutory stock options and the issuance of restricted stock awards. As of December 31, 2013 and September 30, 2014, there were 905,796 and 1,544,615 shares, respectively, of common stock authorized for issuance in connection with the Plan, of which there were 224,734 and 0 shares available for future issuance, respectively.

	Incentive options may be granted to employees, including members of the Board. Non-statutory stock options and purchase rights are granted to employees and consultants of the Company, including members of the Board and advisory board members. The terms of the stock option agreements, including the purchase price per share payable upon exercise of the non-statutory options, are determined by the Board. The exercise price of the incentive options shall not be less than the fair market value per share of common stock on the date of grant. The maximum term of the options granted is ten years, unless an employee owns more than 10% of the total combined voting power of all classes of stock of the Company.

	Certain options are eligible for exercise prior to vesting. Exercised but unvested shares are subject to repurchase by the Company at the initial exercise price. The proceeds from the shares subject to repurchase are classified as a liability and reclassified to equity as the shares vest. Under the 2013 Plan’s early exercise feature, the Company could be required to repurchase 10,166 shares at $3.65 per share as of September 30, 2014. The Company records cash received from early exercised shares as a liability. As of September 30, 2014, $37,000 has been recorded as a liability and included in accrued expenses. In connection with the Company’s initial public offering, no further grants will be made under this plan and all remaining shares available for grant were transferred to the 2014 Incentive Plan.

	2014 Equity Incentive Plan

	The Company adopted a 2014 Equity Incentive Plan that became effective on July 30, 2014 and serves as the successor to the 2013 Equity Incentive Plan. The 2014 Equity Incentive Plan provides for the grant of awards to employees, directors, consultants, independent contractors and advisors, provided the consultants, independent contractors, directors and advisors are natural persons that render services not in connection with the offer and sale of securities in a capital-raising transaction. The exercise price of stock options must be at least equal to the fair market value of our common stock on the date of grant.

	The Company has reserved 1,092,085 shares of its common stock to be issued under the 2014 Equity Incentive Plan of which 1,013,960 shares were available for future issuance as of September 30, 2014. Shares will increase automatically on January 1 of each year from 2015 through 2024 by the number of shares equal to 3.0% of the aggregate number of outstanding shares of our common stock as of the immediately preceding December 31. The Company’s Board may reduce the amount of the increase in any particular year.

	The 2014 Equity Incentive Plan authorizes the award of stock options, restricted stock awards, or RSAs, stock appreciation rights, or SARs, restricted stock units, or RSUs, performance awards and stock bonuses.

	The following table summarizes stock option activity under the 2013 and 2014 Plans for the period from December 31, 2013 through September 30, 2014:

								Average
						Weighted-		Remaining	Aggregate
			Number			Average		Contractual	Intrinsic value
			of Shares			Exercise Price		Term (in years)	(in thousands)
	Outstanding at December 31, 2013		681,056			$	1.18	9.92
	Granted		941,667			5
	Exercised		(114,818		)	1.45
	Cancelled		—			—
	Forfeited		—			—
	Outstanding at September 30, 2014		1,507,905			$	3.54	9.51	$	14,358
	Vested and expected to vest at September 30, 2014		1,507,905			$	3.54	9.51	$	14,358
	Exercisable at September 30, 2014		187,835			$	2.07	9.38	$	2,077
	Weighted-average grant date fair value of options granted during the nine months ended September 30, 2014		$	9.54


	As of September 30, 2014, there was $10.4 million of total unrecognized compensation expense related to options granted but not yet vested. This amount will be recognized as expense over a weighted-average period of 3.44 years.

	The Company uses the Black-Scholes option pricing model to estimate the fair value of option awards with the following weighted-average assumptions, which are based on industry comparative information, for the period indicated:

			Nine Months
			Ended
			September 30, 2014
	Risk-free interest rate		2.02	%
	Expected dividend yield		0	%
	Expected stock price volatility		89.28	%
Expected term of options (in years)		6.66
Expected forfeiture rate		0	%

The weighted-average valuation assumptions were determined as follows:

· Risk-free interest rate: The Company bases the risk-free interest rate on the interest rate payable on U.S. Treasury securities in effect at the time of grant for a period that is commensurate with the assumed expected option term.

· Expected annual dividends: The estimate for annual dividends is 0%, because the Company has not historically paid, and does not expect for the foreseeable future to pay, a dividend.

· Expected stock price volatility: The expected volatility used is based on historical volatilities of similar entities within the Company’s industry which were commensurate with the Company’s expected term assumption.

· Expected term of options: The expected term of options represents the period of time options are expected to be outstanding. The expected term of the options granted to employees is derived from the “simplified” method as described in SAB 107 relating to stock-based compensation. The expected term for options granted to non-employees is equal to the contractual term of the awards.

· Expected forfeiture rate: The Company’s estimated annual forfeiture rate was 0%, based on historical forfeiture experience of various employee groups.

· The estimated fair value of the Company’s stock-based awards is amortized on a straight-line basis over the awards’ service period for those awards with graded vesting and which contain only a service condition. For awards with graded vesting and a performance and service condition, when achievement of the performance condition is deemed probable, the Company recognizes compensation cost using the accelerated recognition method over the awards’ service period.

Share-based compensation expense recognized was as follows (in thousands):

		Three Months			Nine Months
		Ended September 30,			Ended September
		2014			30, 2014
Research and development		$	1,712		$	2,037
General and administrative		323			535
		$	2,035		$	2,572

2014 Employee Stock Purchase Plan

The Company adopted a 2014 Employee Stock Purchase Plan (“ESPP”) that became effective on July 31, 2014, which was the effective date of the Company’s registration statement. The ESPP provides employees of the Company, including any parent or subsidiary companies that the Board designates from time to time as a corporation that shall participate in the plan, with a means of acquiring an equity interest in the Company and to provide an incentive for continued employment.

There are 149,600 shares of common stock reserved for future issuances under the ESPP. Any employee regularly employed by the Company for six months or more on a full-time or part-time basis (20 hours or more per week on a regular schedule) will be eligible to participate in the plan. The ESPP will operate in successive six month offering periods. Each eligible employee who has elected to participate may purchase up to 1,000 shares or $25,000 during each offering period. The purchase price will be the lower of (i) 85% of the fair market value of a share of common stock on the first trading day of the offering period or (ii) 85% of the fair market value of a share of common stock on the last trading day of the offering period. The ESPP will continue for a period of ten years from the first purchase date under the plan unless otherwise terminated by the Board. As of November 14, 2014, no commencement date for the first offering period has been approved by the Board or compensation committee and no shares have been issued under the ESPP.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2014
Commitments and Contingencies.	'
Commitments and Contingencies	'
	6. Commitments and Contingencies

	Array Collaboration Agreement

	On July 3, 2013, the Company signed a multi-year strategic collaboration agreement with Array, and this agreement was subsequently amended on November 26, 2013, April 10, 2014 and October 13, 2014. Under the terms of the collaboration agreement, the Company obtained certain rights to Array’s TRK inhibitor program, as well as additional novel oncology targets. The Company has worldwide commercial rights to each product candidate from the collaboration and Array participates in any potential successes through milestones, royalties, and an equity ownership in the Company.

	With respect to the discovery and preclinical program, the collaboration agreement runs through July 3, 2016, and the Company has the option to extend the term for up to two additional one-year renewal periods by providing written notice to Array at least three months before the end of the initial discovery and preclinical development programs or the renewal period, if applicable. In addition to LOXO-101, the parties designated 12 discovery targets, of which seven are to be selected for additional study on or before January 2015, which will be reduced to four on or before January 2016. The Company has the option to increase the total candidate selection number to five for a modest additional payment.

	As part of the agreement the Company agreed to pay Array a fixed amount per month, based on Array’s commitment to provide full-time equivalents and other support relating to the conduct of the discovery and preclinical development programs. The Company recorded related-party research and development expenses of $8.1 million and $2.4 million for the three months ended September 30, 2013 and 2014, respectively and $8.2 million and $5.4 million for the period from May 9, 2013 (Date of Inception) to September 30, 2013 and the nine months ended September 30, 2014, respectively. The related-party research and development expenses were related to the conduct of the discovery preclinical development programs by Array.

	Milestones

	With respect to product candidates directed to TRK, including LOXO-101 and its back-up compounds, the Company could be required to pay Array up to $222 million in milestone payments, the substantial majority of which are due upon the achievement of commercial milestones. With respect to product candidates directed to targets other than TRK, the Company could be required to pay Array up to $213 million in milestone payments, the substantial majority of which are due upon the achievement of commercial milestones.

	Royalties

	The Company is required to pay Array mid-single digit royalties on worldwide net sales of products directed to TRK and directed to targets. With respect to the royalty on products directed to targets, the Company has the right to credit certain milestone payments against royalties on sales of products directed to such target.

	Convertible preferred stock issuance

	In connection with this agreement, the Company issued Array 500,704 shares of Series A-1 convertible preferred stock, par value $0.0001. The Company recognized, as a component of research and development expense with related party approximately $7.0 million related to the estimated fair value of the shares issued during the period from May 9, 2013 (date of inception) to December 31, 2013. As previously discussed in Note 1, the Company completed its initial public offering in August 2014. As part of that offering, all of the convertible preferred stock was converted into shares of common stock.

	Research and Development Arrangements

	In the course of normal business operations, the Company enters into agreements with contract service organizations, or CROs, to assist in the performance of research and development and preclinical activities. Expenditures to CROs may represent a significant cost in preclinical development for the Company in future periods. The Company can elect to discontinue the work under these agreements at any time. The Company could also enter into additional collaborative research, contract research, manufacturing, and supplier agreements in the future, which may require upfront payments and even long-term commitments of cash.

	Legal Proceedings

	The Company is not involved in any legal proceeding that it expects to have a material effect on its business, financial condition, results of operations and cash flows.

Related_Party_Transactions

Related Party Transactions	9 Months Ended
Related Party Transactions	Sep. 30, 2014
Related Party Transactions	'
Related Party Transactions	'
	7. Related Party Transactions

	The Company recorded related-party research and development expenses of $8.1 million and $2.4 million for the three months ended September 30, 2013 and 2014, respectively and $8.2 million and $5.4 million for the period from May 9, 2013 (Date of Inception) to September 30, 2013 and the nine months ended September 30, 2014, respectively, as a component of research and development with a related party for services provided by Array under the collaboration agreement as described in further detail above in Note 6. As of September 30, 2014, the Company had $0.6 million in prepaid expenses to Array under the collaboration agreement for services that will be provided in subsequent periods.

	In October 2014, Dr. Lori Kunkel was appointed a member of the Company’s board of directors as discussed in Note 8 Subsequent Events. Dr. Kunkel has a consulting agreement with the Company to assist in the Company’s drug development process. Dr. Kunkel is eligible to receive a maximum of $15,000 monthly for her consulting work. Payments are expensed as incurred and recorded as a component of research and development expenses. During the three and nine months ended September 30, 2014, the Company recognized expenses of $30,000 and $51,000, respectively, in accordance with the terms of the consulting agreement. As of September 30, 2014, there was $15,000 included in accounts payable to Dr. Kunkel.

Subsequent_Events

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2014
Subsequent Events	'
Subsequent Events	'
	8. Subsequent Events

	On October 13, 2014, the Company and Array entered into the third amendment to the collaboration agreement. Pursuant to the amendment, the parties agreed to change the number of targets that were discontinued, and the timing of such discontinuation, as described in Note 6.

	On October 23, 2014, the board of directors appointed Dr. Lori Kunkel as a Class II director. Pursuant to that certain Consulting Letter Agreement entered into by and between Loxo and Dr. Kunkel on June 23, 2014, Dr. Kunkel currently holds 26,840 shares of common stock of Loxo and options representing the right to purchase 109,374 shares of common stock of Loxo, together representing approximately $1.7 million and she receives up to a maximum of $15,000 monthly for her consulting work. She will receive no additional compensation as a director.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2014
Summary of Significant Accounting Policies	'
Basis of Presentation	'
	Basis of Presentation

	The accompanying financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”).
Unaudited Interim Financial Information	'
	Unaudited Interim Financial Information

	The accompanying balance sheet as of December 31, 2013, was derived from the Company’s audited financial statements included in Form S-1 filed on July 30, 2014 with the SEC that was declared effective on July 31, 2014.

	The accompanying balance sheet as of September 30, 2014, the statements of operations for the three and nine months ended September 30, 2014, the three months ended September 30, 2013 and the period from May 9, 2013 (Date of Inception) to September 30, 2013, the statements of redeemable convertible preferred stock and stockholders’ (deficit) equity for the nine months ended September 30, 2014 and the statements of cash flows for the nine months ended September 30, 2014 and the period from May 9, 2013 (Date of Inception) to September 30, 2013 are unaudited. The interim unaudited financial statements have been prepared on the same basis as the annual audited financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2014 and the results of its operations for the three and nine months ended September 30, 2014, the three months ended September 30, 2013 and the period from May 9, 2013 (Date of inception) to September 30, 2013, and its cash flows for the nine months ended September 30, 2014 and the period from May 9, 2013 (Date of inception) to September 30, 2013. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2014, the three months ended September 30, 2013 and for the period from May 9, 2013 (Date of inception) to September 30, 2013 are unaudited. The results for the nine months ended September 30, 2014 are not necessarily indicative of results to be expected for the year ending December 31, 2014, any other interim periods or any future year or period. These unaudited financial statements should be read in conjunction with the audited financial statements and the notes thereto for the year ended December 31, 2013 included in the Company’s Form S-1 filed July 30, 2014 with the SEC.
Property and Equipment	'
	Property and Equipment

	Property and equipment are depreciated using the straight-line method over the estimated useful lives of the assets, which are generally three to five years. Maintenance and repairs are expensed as incurred. Upon disposal, retirement, or sale, the related cost and accumulated depreciation is removed from the accounts and any resulting gain or loss is included in the results of operations. The Company recognized depreciation expense of $1,000 during the three and nine months ended September 30, 2014. There was no depreciation during the three months ended September 30, 2013 and during the period from May 9, 2013 (Date of Inception) to September 30, 2013.
Research and Development Expenses	'
	Research and Development Expenses

	Research and development costs are charged to expense as incurred. These costs include, but are not limited to, employee-related expenses, including salaries, benefits, stock-based compensation and travel as well as expenses related to third-party collaborations and contract research agreements; expenses incurred under agreements with contract research organizations and investigative sites that conduct preclinical studies; the cost of acquiring, developing and manufacturing clinical trial materials; facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, insurance and other supplies; and costs associated with preclinical activities and regulatory operations.

	Costs for certain development activities, such as preclinical studies, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, preclinical site activations, or information provided to the Company by its vendors with respect to their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the consolidated financial statements as prepaid or accrued research and development expense, as the case may be.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements

	On August 27, 2014, the FASB issued ASU 2014-15 Presentation of Financial Statement-Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern, which provides guidance on determining when and how reporting entities must disclose going-concern uncertainties in their financial statements. The new standard requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date of issuance of the entity’s financial statements (or within one year after the date on which the financial statements are available to be issued, when applicable). Further, an entity must provide certain disclosures if there is “substantial doubt about the entity’s ability to continue as a going concern.” The FASB believes that requiring management to perform the assessment will enhance the timeliness, clarity, and consistency of related disclosures and improve convergence with IFRSs (which emphasize management’s responsibility for performing the going-concern assessment). However, the time horizon for the assessment (look-forward period) and the disclosure thresholds under U.S. GAAP and IFRSs will continue to differ. The Company does not anticipate that the adoption of this standard will have a material impact on its financial statements.

	On June 10, 2014, the FASB issued ASU No. 2014-10, Development Stage Entities (Topic 915): Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 810, Consolidation. The guidance is intended to reduce the overall cost and complexity associated with financial reporting for development stage entities without reducing the availability of relevant information. The Board also believes the changes will simplify the consolidation accounting guidance by removing the differential accounting requirements for development stage entities. As a result of these changes, there no longer will be any accounting or reporting differences in GAAP between development stage entities and other operating entities. For organizations defined as public business entities the presentation and disclosure requirements in Topic 915 will no longer be required starting with the first annual period beginning after December 15, 2014, including interim periods therein. Early application is permitted for any annual reporting period or interim period for which the entity’s financial statements have not yet been issued (public business entities) or made available for issuance (other entities). The Company early adopted this guidance during the three months ended June 30, 2014 and, as a result, the Company no longer presents inception-to-date information about the statements of operations, cash flows, and stockholders’ (deficit) equity.

	In June 2014, the FASB issued ASU No. 2014-12, Compensation - Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide that a Performance Target Could be Achieved after the Requisite Service Period, (“ASU 2014-12”). ASU 2014-12 requires that a performance target that affects vesting, and that could be achieved after the requisite service period, be treated as a performance condition. As such, the performance target should not be reflected in estimating the grant date fair value of the award. This update further clarifies that compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the period(s) for which the requisite service has already been rendered. The Company does not anticipate that the adoption of this standard will have a material impact on its financial statements.
Reclassifications	'
	Reclassifications

	Certain reclassifications were made to prior period amounts to correct the previous presentation. During the nine months ended September 30, 2014, certain expenses that had been previously classified as general and administrative were reclassified into research and development. The Company reclassified $56 and $167 of expenses related to the three months ended March 31, 2014 and June 30, 2014, respectively.

Net_Loss_Per_Common_Share_Tabl

Net Loss Per Common Share (Tables)	9 Months Ended
Net Loss Per Common Share (Tables)	Sep. 30, 2014
Net Loss Per Common Share	'
Schedule of computation of basic and diluted net loss per share	'
	The following table sets forth the computation of basic and diluted net loss per share for the periods indicated (in thousands, except share and per share data):

								Period From
		Three Months			Three Months			May 9, 2013			Nine Months
		Ended			Ended			(Date of Inception)			Ended
		September 30,			September 30,			to September 30,			September 30,
		2013			2014			2013			2014

	Basic and diluted net loss per common share calculation:
	Net loss	$	(8,345	)	$	(6,743	)	$	(8,435	)	$	(13,550	)
	Accretion of redeemable convertible preferred stock	—			(6		)	—			(34		)
	Net loss attributable to common stockholders	$	(8,345	)	$	(6,749	)	$	(8,435	)	$	(13,584	)
	Weighted average common shares outstanding	184,605			9,947,321			117,942			3,510,170
	Net loss per share of common stock—basic and diluted	$	(45.20	)	$	(0.68	)	$	(71.52	)	$	(3.87	)
Schedule of outstanding securities excluded from the computation of diluted weighted average shares outstanding, as they would have been anti-dilutive	'


		2013		2014
	Redeemable convertible preferred stock	3,313,201		—
	Unvested restricted stock	264,190		187,134
	Stock options	—		1,507,905
		3,577,391		1,695,039

Accrued_Expenses_Tables

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2014
Accrued Expenses	'
Schedule of accrued expenses	'
	Accrued expenses consisted of the following (in thousands):

		December 31,		September 30,
		2013		2014
	Research and development expenses	$	81	$	239
	General and administrative expenses	108		244
	Share repurchase obligation	—		37
		$	189	$	520

Capital_Stock_Redeemable_Conve1

Capital Stock, Redeemable Convertible Preferred Stock, and Stockholders' (Deficit) Equity (Tables)	9 Months Ended
	Sep. 30, 2014
Capital Stock, Redeemable Convertible Preferred Stock, and Stockholders' (Deficit) Equity	'
Summary of stock option activity under the 2013 and 2014 Plan	'


							Average
					Weighted-		Remaining	Aggregate
		Number			Average		Contractual	Intrinsic value
		of Shares			Exercise Price		Term (in years)	(in thousands)
	Outstanding at December 31, 2013	681,056			$	1.18	9.92
	Granted	941,667			5
	Exercised	(114,818		)	1.45
	Cancelled	—			—
	Forfeited	—			—
	Outstanding at September 30, 2014	1,507,905			$	3.54	9.51	$	14,358
	Vested and expected to vest at September 30, 2014	1,507,905			$	3.54	9.51	$	14,358
	Exercisable at September 30, 2014	187,835			$	2.07	9.38	$	2,077
	Weighted-average grant date fair value of options granted during the nine months ended September 30, 2014	$	9.54

Schedule of weighted-average assumptions under the Black-Scholes option pricing model estimate the fair value of option awards	'


		Nine Months
		Ended
		September 30, 2014
	Risk-free interest rate	2.02	%
	Expected dividend yield	0	%
	Expected stock price volatility	89.28	%
	Expected term of options (in years)	6.66
	Expected forfeiture rate	0	%
Schedule of Share-based compensation expense recognized	'
	Share-based compensation expense recognized was as follows (in thousands):

		Three Months			Nine Months
		Ended September 30,			Ended September
		2014			30, 2014
	Research and development	$	1,712		$	2,037
	General and administrative	323			535
		$	2,035		$	2,572

Organization_and_Description_o1

Organization and Description of the Business (Details) (USD $)

0 Months Ended

1 Months Ended

5 Months Ended

9 Months Ended

0 Months Ended

1 Months Ended

Jul. 03, 2013

Aug. 31, 2014

Jul. 31, 2014

Sep. 30, 2013

Sep. 30, 2014

Dec. 31, 2013

Aug. 06, 2014

Sep. 04, 2014

Aug. 31, 2014

item

Convertible Preferred Stock [Member]

Initial public offering

Private placement

Over-allotment option

Net offering proceeds

Offering expenses

Organization and Description of the Business

Number of operating segments

Organization and description of the business

Stock split ratio of the common stock

0.48309

1.5625

Shares of common stock sold

5,261,538

230,769

642,000

Initial public offering price (in dollars per share)

$13

Aggregate gross proceeds from shares sold

$68,400,000

$72,400,000

Aggregate gross proceeds from shares sold

3,000,000

Aggregate shares of common stock issued upon conversion of all outstanding convertible preferred stock

9,932,042

Underwriters underwriting discounts and commissions paid

5,600,000

Offering expense

1,700,000

Aggregate gross proceeds from shares sold

1,000

74,331,000

8,300,000

Working capital

119,300,000

Accumulated deficit

23,840,000

10,290,000

Cash and cash equivalents

$16,291,000

$118,621,000

$14,994,000

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended		5 Months Ended	9 Months Ended	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Sep. 30, 2014	Sep. 30, 2014
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2014	Research and development expenses	Research and development expenses	Minimum	Maximum
Property and equipment	'	'	'	'	'	'	'	'
Estimated useful lives of the assets	'	'	'	'	'	'	'3 years	'5 years
Depreciation expense	$1	$0	$0	$1	'	'	'	'
General and administrative expenses reclassified into research and development	'	'	'	'	$167	$56	'	'

Net_Loss_Per_Common_Share_Deta

Net Loss Per Common Share (Details) (USD $)	3 Months Ended		5 Months Ended	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Basic and diluted net loss per common share calculation:	'	'	'	'	'
Net loss	($6,743)	($8,345)	($8,435)	($13,550)	'
Accretion of redeemable convertible preferred stock	-6	'	'	-34	'
Net loss attributable to common stockholders	($6,749)	($8,345)	($8,435)	($13,584)	'
Weighted average common shares outstanding	9,947,321	184,605	117,942	3,510,170	'
Net loss per share of common stock-basic and diluted (in dollars per share)	($0.68)	($45.20)	($71.52)	($3.87)	'
Outstanding securities excluded from computation of diluted weighted average shares outstanding, as they would have been anti-dilutive	'	'	'	'	'
Total (in shares)	'	'	'	1,695,039	3,577,391
Redeemable convertible preferred stock	'	'	'	'	'
Outstanding securities excluded from computation of diluted weighted average shares outstanding, as they would have been anti-dilutive	'	'	'	'	'
Total (in shares)	'	'	'	'	3,313,201
Unvested restricted stock	'	'	'	'	'
Outstanding securities excluded from computation of diluted weighted average shares outstanding, as they would have been anti-dilutive	'	'	'	'	'
Total (in shares)	'	'	'	187,134	264,190
Stock options	'	'	'	'	'
Outstanding securities excluded from computation of diluted weighted average shares outstanding, as they would have been anti-dilutive	'	'	'	'	'
Total (in shares)	'	'	'	1,507,905	'

Accrued_Expenses_Details

Accrued Expenses (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Accrued Expenses	'	'
Accrued expenses	$520	$189
Research and development expenses	'	'
Accrued Expenses	'	'
Accrued expenses	239	81
General and administrative expenses	'	'
Accrued Expenses	'	'
Accrued expenses	244	108
Shares repurchase obligation	'	'
Accrued Expenses	'	'
Accrued expenses	$37	'

Capital_Stock_Redeemable_Conve2

Capital Stock, Redeemable Convertible Preferred Stock, and Stockholders' (Deficit) Equity (Details) (USD $)

0 Months Ended

9 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

2 Months Ended

In Millions, except Share data, unless otherwise specified

Aug. 06, 2014

Sep. 30, 2014

Jul. 21, 2014

Dec. 31, 2013

Aug. 06, 2014

Aug. 07, 2014

Jul. 21, 2014

Aug. 07, 2014

Jul. 03, 2013

Jun. 28, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Jul. 21, 2014

Dec. 31, 2013

Aug. 07, 2014

Sep. 30, 2014

Jul. 21, 2014

Mar. 31, 2014

Dec. 31, 2013

Mar. 18, 2014

Sep. 19, 2013

Feb. 28, 2014

Jul. 03, 2013

Sep. 30, 2014

Jul. 21, 2014

Dec. 31, 2013

Jul. 03, 2013

Jul. 21, 2014

Jun. 30, 2014

Apr. 30, 2014

Jun. 24, 2014

Apr. 24, 2014

Jun. 24, 2014

Initial public offering

Common stock

Preferred stock

Series A preferred stock

Series A-1 preferred stock

Series B preferred stock

Initial public offering

Co-founders

Two co-founders

Initial public offering

Investors

Collaboration agreement

Stock purchase agreement

item

Vesting on July 3, 2014

Vesting in equal monthly installments over a specific period thereafter

Stock purchase agreement

Array

Maximum

Capitalization

Capital stock, shares authorized

31,010,691

15,031,954

130,000,000

Common stock, shares authorized

125,000,000

9,375,000

22,187,500

125,000,000

Common stock, par value (in dollars per share)

$0.00

Preferred stock, shares authorized

8,823,191

5,656,954

5,000,000

5,156,250

2,812,497

500,704

3,166,237

Preferred stock, par value (in dollars per share)

$0.00

Shares issued

5,261,538

452,896

501,890

2,664,343

Number of co-founders to whom stock is issued and is subject to vesting pursuant to the restricted stock agreements

Number of shares issued that are subject to vesting pursuant to the restricted stock agreements

264,190

Vesting percentage

25.00%

75.00%

Vesting term

'3 years

Shares issued

2,812,497

1,249,997

2,343,753

1,562,500

500,704

Net proceeds

$15

$17.80

$28.40

Estimated fair value

Share purchase price (in dollars per share)

$6.40

$8.97

Number of shares of common stock into which outstanding convertible preferred stock are converted

9,932,042

Capital_Stock_Redeemable_Conve3

Capital Stock, Redeemable Convertible Preferred Stock, and Stockholders' (Deficit) Equity (Details 2) (USD $)

Aug. 06, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Jul. 02, 2014

Sep. 30, 2014

Jul. 31, 2014

Initial public offering

2013 and 2014 Equity Incentive Plans

2013 Equity Incentive Plan

2014 Equity Incentive Plan

2014 Employee Stock Purchase Plan

Stock option

Minimum

Stock option

First day of trading

Last day of trading in offering period

Minimum

Maximum

2013 and 2014 Equity Incentive Plan

Shares authorized for issuance

1,544,615

905,796

1,092,085

Shares available for future issuance

224,734

1,013,960

Term of award

'10 years

Combined voting power of all classes of stock owned used to determine term of award (as a percent)

10.00%

Shares that could be required to be repurchased

10,166

Price of shares that could be required to be repurchased

$3.65

Shares subject to repurchase liability, amount recorded in accrued expenses

$37,000

Increase in common stock reserved for issuance as percentage of the aggregate number of outstanding shares of common stock

3.00%

Number of Shares

Outstanding at the beginning of the period (in shares)

681,056

Granted (in shares)

941,667

Exercised (in shares)

-114,818

Outstanding at the end of the period (in shares)

1,507,905

681,056

Vested and expected to vest at the end of the period (in shares)

1,507,905

Exercisable at the end of the period (in shares)

187,835

Weighted average grant date fair value of options granted (in dollars per share)

$9.54

Weighted Average Exercise Price

Outstanding at the beginning of the period (in dollars per share)

$1.18

Granted (in dollars per share)

Exercised (in dollars per share)

$1.45

Outstanding at the end of the period (in dollars per share)

$3.54

$1.18

Vested and expected to vest at the end of the period (in dollars per share)

$3.54

Exercisable at the end of the period (in dollars per share)

$2.07

Average Remaining Contractual Term

Outstanding at the beginning of the period

'9 years 6 months 4 days

'9 years 11 months 1 day

Outstanding at the end of the period

'9 years 6 months 4 days

'9 years 11 months 1 day

Vested and expected to vest at the end of the period

'9 years 6 months 4 days

Exercisable at the end of the period

'9 years 4 months 17 days

Aggregate Intrinsic value

Outstanding at the end of the period

14,358,000

Vested and expected to vest at the end of the period

14,358,000

Exercisable at the end of the period

2,077,000

Additional disclosures

Unrecognized compensation expense

10,400,000

Weighted-average period for recognition

'3 years 5 months 8 days

Weighted average assumptions used to estimate fair value of option awards using Black Scholes option pricing model

Risk-free interest rate

2.02%

Expected dividend yield

0.00%

Expected stock price volatility

89.28%

Expected term of options (in years)

'6 years 7 months 6 days

Expected forfeiture rate

0.00%

Fair value of common stock (in dollars per share)

$13

Shares of common stock reserved for issuance under the plan

149,600

Employment period required to participate in the plan

'6 months

Period per week on a regular schedule required to participate in the plan

'20 hours

Maximum shares which may be purchased by eligible employee

1,000

Maximum value of shares which may be purchased by eligible employee

$25,000

Purchase price as percentage of fair market value of a share of common stock

85.00%

Award term

'P10Y

Shares issued under the plan

Capital_Stock_Redeemable_Conve4

Capital Stock, Redeemable Convertible Preferred Stock, and Stockholders' (Deficit) Equity (Details 3) (Plan, USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2014
Stock based compensation expense	'	'
Share-based compensation expense	$2,035	$2,572
Research and development	'	'
Stock based compensation expense	'	'
Share-based compensation expense	1,712	2,037
General and administrative	'	'
Stock based compensation expense	'	'
Share-based compensation expense	$323	$535

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)

3 Months Ended

5 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

3 Months Ended

5 Months Ended

3 Months Ended

5 Months Ended

9 Months Ended

8 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Oct. 13, 2014

Sep. 30, 2014

Jul. 03, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Dec. 31, 2013

Series A-1 preferred stock

Collaboration agreement

Array

Maximum

Series A-1 preferred stock

Product candidates directed to TRK

Product candidates directed to targets other than TRK

Related party

Subsequent event

Array

Research and development

Array

Product candidates directed to targets other than TRK

item

Research and development

Array

Commitments and contingencies

Number of additional renewal periods options available to the entity to extend agreement term

Term of additional renewal periods options available to the entity to extend agreement term

'1 year

Number of discovery targets designated by the parties

Number of discovery targets which are to be selected for additional study on or before January 2015

Number of discovery targets which are to be selected for additional study on or before October 2015

Maximum number of candidates which can be selected by the entity for modest additional payment

Related party research and development expenses

$2,400,000

$5,400,000

$8,100,000

$8,200,000

$2,400,000

$8,100,000

$8,200,000

$5,400,000

Maximum milestone payments which the entity could be required to pay

222,000,000

213,000,000

Research and development

$2,623,000

$37,000

$43,000

$4,412,000

$7,000,000

Shares issued

500,704

Redeemable convertible preferred stock, par value (in dollars per share)

$0.00

Related_Party_Transactions_Det

Related Party Transactions (Details) (USD $)

9 Months Ended

0 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

5 Months Ended

3 Months Ended

5 Months Ended

9 Months Ended

Sep. 30, 2014

Oct. 23, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Dr. Lori Kunkel

Collaboration agreement

Accounts payable

Subsequent event

Research and development

Array

Related party

Research and development

Array

Research and development

Related party transactions

Related party research and development expenses

$2,400,000

$5,400,000

$8,100,000

$8,200,000

$2,400,000

$8,100,000

$8,200,000

$5,400,000

Prepaid expenses

600,000

Maximum monthly fees for consulting work

15,000

Expenses recognized for consulting work

168,000

30,000

51,000

Amount payable to related parties

$15,000

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Oct. 23, 2014
			Dr. Lori Kunkel
			Subsequent event
Subsequent events	'	'	'
Common stock held (in shares)	16,634,063	452,896	26,840
Right to purchase common stock (in shares)	'	'	109,374
Total common stock held	'	'	$1,700,000
Maximum monthly fees for consulting work	'	'	15,000
Additional compensation	'	'	$0