Kura Oncology (KURA) 10-Q 6 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Aug. 03, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	KURA
Entity Registrant Name	Kura Oncology, Inc.
Entity Central Index Key	1,422,143
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		37,975,302

Condensed Balance Sheets (Unaud

Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	[1]
Current assets:
Cash and cash equivalents	$ 17,658	$ 11,433
Short-term investments	108,227	81,712
Accounts receivable, related party	230	216
Prepaid expenses and other current assets	2,420	1,280
Total current assets	128,535	94,641
Property and equipment, net	1	10
Other long-term assets	1,091	1,200
Total assets	129,627	95,851
Current liabilities:
Accounts payable and accrued expenses	9,330	8,284
Accounts payable and accrued expenses, related party	437	216
Current portion of long-term debt, net	2,813	1,531
Total current liabilities	12,580	10,031
Long-term debt, net	4,150	5,567
Other long-term liabilities	500	388
Total liabilities	17,230	15,986
Stockholders' equity:
Preferred stock, $0.0001 par value; 10,000 shares authorized; no shares issued and outstanding
Common stock, $0.0001 par value; 200,000 shares authorized; 33,375 and 30,217 shares issued as of June 30, 2018 and December 31, 2017, respectively; and 33,173 and 29,424 shares outstanding as of June 30, 2018 and December 31, 2017, respectively; excluding 202 and 793 shares subject to repurchase as of June 30, 2018 and December 31, 2017, respectively	3	3
Additional paid-in capital	231,120	169,201
Accumulated other comprehensive loss	(93)	(49)
Accumulated deficit	(118,633)	(89,290)
Total stockholders' equity	112,397	79,865
Total liabilities and stockholders' equity	$ 129,627	$ 95,851
[1]	The balance sheet data at December 31, 2017 has been derived from audited financial statements at that date. It does not include, however, all of the information and notes required by U.S. generally accepted accounting principles for complete financial statements.

Condensed Balance Sheets (Unau3

Condensed Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017	[1]
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	33,375,000	30,217,000
Common stock, shares outstanding	33,173,000	29,424,000
Number of shares, subject to repurchase	202,000	793,000
[1]	The balance sheet data at December 31, 2017 has been derived from audited financial statements at that date. It does not include, however, all of the information and notes required by U.S. generally accepted accounting principles for complete financial statements.

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Operating Expenses:
Research and development	$ 11,099	$ 5,158	$ 22,366	$ 10,378
Research and development, related party	377	494	676	787
General and administrative	3,736	2,217	7,102	4,292
General and administrative, related party	64	61	123	126
Total operating expenses	15,276	7,930	30,267	15,583
Other Income (Expense):
Management fee income, related party	180	195	375	390
Interest income	624	124	1,074	252
Interest expense	(267)	(209)	(525)	(412)
Total other income	537	110	924	230
Net Loss	$ (14,739)	$ (7,820)	$ (29,343)	$ (15,353)
Net loss per share, basic and diluted	$ (0.45)	$ (0.40)	$ (0.91)	$ (0.78)
Weighted average number of shares used in computing net loss per share, basic and diluted	32,971	19,789	32,403	19,627
Comprehensive Loss:
Net Loss	$ (14,739)	$ (7,820)	$ (29,343)	$ (15,353)
Other comprehensive loss	(25)	(3)	(44)	(4)
Comprehensive Loss	$ (14,764)	$ (7,823)	$ (29,387)	$ (15,357)

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017
Operating Activities
Net loss	$ (29,343)		$ (15,353)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	4,415		1,924
Non-cash interest expense	114		32
Depreciation expense	9		16
Amortization of premium and accretion of discounts on marketable securities	(703)		3
Changes in operating assets and liabilities:
Accounts receivable, related party	(14)		(9)
Prepaid expenses and other current assets	(1,026)		(462)
Other long-term assets	(42)		(117)
Accounts payable and accrued expenses	814		(502)
Accounts payable and accrued expenses, related party	221		(373)
Other long-term liabilities	112		109
Net cash used in operating activities	(25,443)		(14,732)
Investing Activities
Purchases of marketable securities	(106,850)		(19,360)
Maturities of marketable securities	80,993		36,327
Net cash (used in) provided by investing activities	(25,857)		16,967
Financing Activities
Proceeds from issuance of common stock, net	57,650		159
Proceeds from exercise of stock options	125		35
Repayment of long-term debt	(250)
Net cash provided by financing activities	57,525		194
Net increase in cash and cash equivalents	6,225		2,429
Cash and cash equivalents at beginning of period	11,433	[1]	9,725
Cash and cash equivalents at end of period	$ 17,658		$ 12,154
[1]	The balance sheet data at December 31, 2017 has been derived from audited financial statements at that date. It does not include, however, all of the information and notes required by U.S. generally accepted accounting principles for complete financial statements.

Organization and Basis of Prese

Organization and Basis of Presentation	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation The Company Kura Oncology, Inc. is a clinical-stage biopharmaceutical company committed to realizing the promise of precision medicines for the treatment of cancer. Our pipeline consists of small molecule product candidates that target cancer signaling pathways, and we intend to pair them with molecular or cellular diagnostics to identify those patients most likely to respond to treatment. We intend to advance our product candidates through a combination of internal development and strategic partnerships and maintain significant development and commercial rights. References in these Notes to Unaudited Condensed Financial Statements to the “Company,” “we,” “our” or “us,” refer to Kura Oncology, Inc. Basis of Presentation The accompanying unaudited condensed financial statements should be read in conjunction with the audited financial statements and notes thereto in our Annual Report on Form 10-K for the fiscal year ended December 31, 2017, as filed with the Securities and Exchange Commission on March 12, 2018, from which we derived our balance sheet as of December 31, 2017. The accompanying condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP, for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, since they are interim statements, the accompanying condensed financial statements do not include all of the information and notes required by GAAP for complete financial statements. The accompanying condensed financial statements reflect all adjustments, consisting of normal recurring adjustments, that are, in the opinion of our management, necessary to a fair statement of the results for the interim periods presented. Interim results are not necessarily indicative of results for a full year. The preparation of the condensed financial statements in accordance with GAAP requires our management to make estimates and assumptions that affect the amounts reported on our condensed financial statements and accompanying notes. The amounts reported could differ under different estimates and assumptions. On an ongoing basis, we evaluate our estimates and judgments, which are based on historical and anticipated results and trends and on various other assumptions that management believes to be reasonable under the circumstances. By their nature, estimates are subject to an inherent degree of uncertainty and, as such, actual results may differ from management’s estimates.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Comprehensive Loss Comprehensive loss is defined as the change in equity during the period from transactions and other events and non-owner sources. For the periods presented, accumulated other comprehensive loss consists of unrealized gains and losses on marketable securities and foreign currency translation adjustments. Net Loss per Share Net loss per common share is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by dividing the net loss by the weighted-average number of common shares and common share equivalents outstanding for the period determined using the treasury-stock method. Dilutive common stock equivalents are comprised of unvested restricted stock awards, outstanding stock options and outstanding warrants. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the antidilutive effect of the securities. Because of our net loss, unvested restricted stock awards, outstanding stock options and outstanding warrants are excluded from the calculation of diluted net loss per common share for the periods presented, due to the anti-dilutive effect of the securities. The following table summarizes the number of potentially dilutive securities that were excluded from our calculation of diluted net loss per share, in thousands: Three and Six Months Ended 2018 2017 Stock options 3,097 2,214 Unvested restricted stock awards 202 1,387 Warrants 34 34 Total 3,333 3,635 Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2016-02, Leases (Topic 842), which requires lessees to recognize a right-to-use asset and a lease obligation for all leases. Additional qualitative and quantitative disclosures, including significant judgments made by management, will be required.

Investments

Investments	6 Months Ended
	Jun. 30, 2018
Investments All Other Investments [Abstract]
Investments	3. Investments We invest in available-for-sale securities consisting of money market funds, U.S. Treasury securities, corporate debt securities and commercial paper. Available-for-sale securities are classified as part of either cash and cash equivalents or short-term investments on our condensed balance sheets. The following tables summarize, by major security type, our investments that are measured at fair value on a recurring basis, in thousands: As of June 30, 2018 Maturities (years) Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents: Money market funds 1 or less $ 11,317 $ — $ — $ 11,317 Commercial paper 1 or less 3,997 — — 3,997 Total cash equivalents 15,314 — — 15,314 Short-term investments: U.S. Treasury securities 2 or less 49,620 1 (85 ) 49,536 Commercial paper 1 or less 47,281 — — 47,281 Corporate debt securities 1 or less 11,424 — (14 ) 11,410 Total short-term investments 108,325 1 (99 ) 108,227 Total $ 123,639 $ 1 $ (99 ) $ 123,541 As of December 31, 2017 Maturities (years) Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents: Money market funds 1 or less $ 5,848 $ — $ — $ 5,848 Commercial paper 1 or less 2,993 — — 2,993 Total cash equivalents 8,841 — — 8,841 Short-term investments: U.S. Treasury securities 2 or less 22,929 — (42 ) 22,887 Commercial paper 1 or less 50,929 — — 50,929 Corporate debt securities 1 or less 7,903 — (7 ) 7,896 Total short-term investments 81,761 — (49 ) 81,712 Total $ 90,602 $ — $ (49 ) $ 90,553 The available-for-sale investments are classified as current assets, even though the stated maturity date may be one year or more beyond the current balance sheet date, which reflects management’s intention to use the proceeds from sales of these securities to fund our operations, as necessary. As of June 30, 2018, $93.4 million of our short-term investments had maturities less than one year, and $14.8 million had maturities between one to two years. There were no realized gains or losses for the three and six months ended June 30, 2018. As of June 30, 2018, $51.0 million of our marketable securities were in gross unrealized loss positions, all of which had been in such position for less than 12 months. We reviewed our marketable securities as of June 30, 2018 and determined that the unrealized losses were not considered to be other-than-temporary based upon (i) the financial strength of the issuing institution and (ii) the fact that all securities have been in an unrealized loss position for less than 12 months. In addition, we do not intend to sell these securities and it is not more likely than not that we will be required to sell these securities before the recovery of their amortized cost basis. As of June 30, 2018, we did not recognize any such impairment in our condensed financial statements.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements As a basis for considering assumptions that market participants would use in pricing an asset or liability, the guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: • Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities; • Level 2 - Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable; and • Level 3 - Unobservable inputs in which little or no market activity exists, therefore requiring an entity to develop its own assumptions about the assumptions that market participants would use in pricing. Available-for-sale marketable securities consist of U.S. Treasury securities, which were measured at fair value using Level 1 inputs, and corporate debt securities and commercial paper, which were measured at fair value using Level 2 inputs. We determine the fair value of Level 2 related securities with the aid of valuations provided by third parties using proprietary valuation models and analytical tools. These valuation models and analytical tools use market pricing or prices for similar instruments that are both objective and publicly available, including matrix pricing or reported trades, benchmark yields, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids and/or offers. We validate the fair values of Level 2 financial instruments by comparing these fair values to a third-party pricing source. No transfers between levels have occurred during the periods presented. The following tables summarize, by major security type, our cash equivalents and short-term investments that are measured at fair value on a recurring basis and are categorized using the fair value hierarchy, in thousands: As of June 30, 2018 Balance Level 1 Level 2 Cash equivalents: Money market funds $ 11,317 $ 11,317 $ — Commercial paper 3,997 — 3,997 Total cash equivalents 15,314 11,317 3,997 Short-term investments: U.S. Treasury securities 49,536 49,536 — Commercial paper 47,281 — 47,281 Corporate debt securities 11,410 — 11,410 Total short-term investments 108,227 49,536 58,691 Total $ 123,541 $ 60,853 $ 62,688 As of December 31, 2017 Balance Level 1 Level 2 Cash equivalents: Money market funds $ 5,848 $ 5,848 $ — Commercial paper 2,993 — 2,993 Total cash equivalents 8,841 5,848 2,993 Short-term investments: U.S. Treasury securities 22,887 22,887 — Commercial paper 50,929 — 50,929 Corporate debt securities 7,896 — 7,896 Total short-term investments 81,712 22,887 58,825 Total $ 90,553 $ 28,735 $ 61,818 We believe that our term loan facility bears interest at a rate that approximates prevailing market rates for instruments with similar characteristics and, accordingly, the carrying value of the term loan facility approximates fair value. The fair value of our term loan facility is determined using Level 2 inputs in the fair value hierarchy.

Accounts Payable and Accrued Li

Accounts Payable and Accrued Liabilities	6 Months Ended
	Jun. 30, 2018
Payables And Accruals [Abstract]
Accounts Payable and Accrued Liabilities	5. Accounts Payable and Accrued Liabilities Accounts payable and accrued liabilities consisted of the following, in thousands: June 30, 2018 December 31, 2017 Accounts payable $ 1,755 $ 1,248 Accrued research and development expenses 5,242 3,852 Accrued compensation and benefits 1,563 2,345 Other accrued expenses 770 839 Total accounts payable and accrued expenses $ 9,330 $ 8,284

Stockholders_ Equity

Stockholders’ Equity	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Stockholders’ Equity	6. Stockholders’ Equity In January 2018, we sold an aggregate of 3,136,722 shares of our common stock under our at-the-market issuance sales agreement with Cowen In July 2018, we completed a public offering in which we sold an aggregate of 4,600,000 shares of common stock at a price of $16.75 per share. Net proceeds from the public offering, after deducting underwriting discounts, commissions and offering expenses, were approximately $74.5 million.

Equity Incentive Plan

Equity Incentive Plan	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity Incentive Plan	7. Equity Incentive Plan The following table summarizes share-based compensation expense for all share-based compensation arrangements, in thousands: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Research and development $ 1,369 $ 678 $ 2,808 $ 1,266 General and administrative 867 352 1,607 658 Total share-based compensation expense $ 2,236 $ 1,030 $ 4,415 $ 1,924 Restricted stock awards: Employee $ 33 $ 33 $ 66 $ 66 Nonemployee 798 445 1,799 828 Total $ 831 $ 478 $ 1,865 $ 894 Stock options: Employee $ 1,349 $ 530 $ 2,429 $ 989 Nonemployee 50 22 115 41 Total $ 1,399 $ 552 $ 2,544 $ 1,030 Employee stock purchase plan: Employee $ 6 $ — $ 6 $ — Total $ 6 $ — $ 6 $ — Pursuant to our , we commenced the first purchase period in the second quarter of 2018. As of June 30, 2018, unrecognized compensation costs related to employee stock options and restricted stock awards were approximately $15.6 million and $0.1 million, respectively, which are expected to be recognized over a weighted average period of approximately 2.7 years and 0.2 years, respectively.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions	8. Related Party Transactions Our president and chief executive officer is also the sole managing member of Araxes Pharma LLC, or • Asset Purchase Agreement Under our asset purchase agreement with Araxes, in the three and six months ended June 30, 2017, we paid a milestone payment of $0.2 million to Araxes following dosing of the first patient in the first KO-947 Phase 1 clinical trial in April 2017. • Facility Sublease We subleased office space in La Jolla, California from Wellspring Biosciences, Inc., or Wellspring, a wholly owned subsidiary of Araxes pursuant to a sublease agreement that expired in June 2017. In December 2016, we entered into a new sublease agreement with Wellspring for office space in San Diego, California, or New Sublease. The New Sublease will expire on October 31, 2019. • Management Fees Effective April 2018, we amended our management services agreement with Araxes. Under the amendment, Araxes pays us a fixed fee of $60,000 per month for management services, which is reduced from the fixed fee of $65,000 per month. In addition, the agreement allows for Araxes to reimburse us an amount equal to the number of full time equivalents, or FTE, performing research and development services for Araxes, at an annual FTE rate of approximately $367,000, plus actual expenses as reasonably incurred. The initial term of this agreement expired on December 31, 2015 but, pursuant to the terms of the agreement, renews automatically for additional consecutive one-year periods. The agreement may be terminated by either party with a notice of at least 30 days prior to the expiration of the then-renewal term. For the three months ended June 30, 2018 and 2017, we recorded reimbursements of approximately $0.1 million in each period, and for the six months ended June 30, 2018 and 2017, we recorded reimbursements of approximately $0.1 million and $0.2 million, respectively, for research and development services provided to Araxes, which was recorded as a reduction to research and development expenses on our condensed statements of operations and comprehensive loss. As of June 30, 2018 and December 31, 2017, approximately $0.2 million related to management fees and reimbursements of research and development services are included in accounts receivable, related party on our condensed balance sheets. • Services Agreement We have a services agreement with Wellspring pursuant to which we pay Wellspring for research and development services provided to us in an amount equal to the number of FTE’s performing the services, at an annual FTE rate of $400,000, plus actual expenses as reasonably incurred. The initial term of this services agreement expired on December 31, 2015 but, pursuant to the terms of the agreement, renews automatically for additional consecutive one-year periods. The agreement may be terminated by either party with a notice of at least 30 days prior to the expiration of the then-renewal term. For the three months ended June 30, 2018 and 2017, we recognized approximately $0.4 million and $0.3 million, respectively, and for both the six months ended June 30, 2018 and 2017, we recognized $0.7 million from research and development services provided to us under this agreement as research and development expense, related party on our condensed statements of operations and comprehensive loss. As of June 30, 2018 and December 31, 2017, approximately $0.4 million and $0.2 million, respectively, related to research and development services under this agreement are included in accounts payable and accrued expenses, related party on our condensed balance sheets.

Summary of Significant Accoun14

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Comprehensive Loss	Comprehensive Loss Comprehensive loss is defined as the change in equity during the period from transactions and other events and non-owner sources. For the periods presented, accumulated other comprehensive loss consists of unrealized gains and losses on marketable securities and foreign currency translation adjustments.
Net Loss per Share	Net Loss per Share Net loss per common share is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by dividing the net loss by the weighted-average number of common shares and common share equivalents outstanding for the period determined using the treasury-stock method. Dilutive common stock equivalents are comprised of unvested restricted stock awards, outstanding stock options and outstanding warrants. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the antidilutive effect of the securities. Because of our net loss, unvested restricted stock awards, outstanding stock options and outstanding warrants are excluded from the calculation of diluted net loss per common share for the periods presented, due to the anti-dilutive effect of the securities. The following table summarizes the number of potentially dilutive securities that were excluded from our calculation of diluted net loss per share, in thousands: Three and Six Months Ended 2018 2017 Stock options 3,097 2,214 Unvested restricted stock awards 202 1,387 Warrants 34 34 Total 3,333 3,635
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2016-02, Leases (Topic 842), which requires lessees to recognize a right-to-use asset and a lease obligation for all leases. Additional qualitative and quantitative disclosures, including significant judgments made by management, will be required.

Summary of Significant Accoun15

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Summary of Number of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share	The following table summarizes the number of potentially dilutive securities that were excluded from our calculation of diluted net loss per share, in thousands: Three and Six Months Ended 2018 2017 Stock options 3,097 2,214 Unvested restricted stock awards 202 1,387 Warrants 34 34 Total 3,333 3,635

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2018
Investments All Other Investments [Abstract]
Investments Measured at Fair Value on Recurring Basis	The following tables summarize, by major security type, our investments that are measured at fair value on a recurring basis, in thousands: As of June 30, 2018 Maturities (years) Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents: Money market funds 1 or less $ 11,317 $ — $ — $ 11,317 Commercial paper 1 or less 3,997 — — 3,997 Total cash equivalents 15,314 — — 15,314 Short-term investments: U.S. Treasury securities 2 or less 49,620 1 (85 ) 49,536 Commercial paper 1 or less 47,281 — — 47,281 Corporate debt securities 1 or less 11,424 — (14 ) 11,410 Total short-term investments 108,325 1 (99 ) 108,227 Total $ 123,639 $ 1 $ (99 ) $ 123,541 As of December 31, 2017 Maturities (years) Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents: Money market funds 1 or less $ 5,848 $ — $ — $ 5,848 Commercial paper 1 or less 2,993 — — 2,993 Total cash equivalents 8,841 — — 8,841 Short-term investments: U.S. Treasury securities 2 or less 22,929 — (42 ) 22,887 Commercial paper 1 or less 50,929 — — 50,929 Corporate debt securities 1 or less 7,903 — (7 ) 7,896 Total short-term investments 81,761 — (49 ) 81,712 Total $ 90,602 $ — $ (49 ) $ 90,553

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Schedule Of Fair Value Measurements, By Major Security Type	The following tables summarize, by major security type, our cash equivalents and short-term investments that are measured at fair value on a recurring basis and are categorized using the fair value hierarchy, in thousands: As of June 30, 2018 Balance Level 1 Level 2 Cash equivalents: Money market funds $ 11,317 $ 11,317 $ — Commercial paper 3,997 — 3,997 Total cash equivalents 15,314 11,317 3,997 Short-term investments: U.S. Treasury securities 49,536 49,536 — Commercial paper 47,281 — 47,281 Corporate debt securities 11,410 — 11,410 Total short-term investments 108,227 49,536 58,691 Total $ 123,541 $ 60,853 $ 62,688 As of December 31, 2017 Balance Level 1 Level 2 Cash equivalents: Money market funds $ 5,848 $ 5,848 $ — Commercial paper 2,993 — 2,993 Total cash equivalents 8,841 5,848 2,993 Short-term investments: U.S. Treasury securities 22,887 22,887 — Commercial paper 50,929 — 50,929 Corporate debt securities 7,896 — 7,896 Total short-term investments 81,712 22,887 58,825 Total $ 90,553 $ 28,735 $ 61,818

Accounts Payable and Accrued 18

Accounts Payable and Accrued Liabilities (Tables)	6 Months Ended
	Jun. 30, 2018
Payables And Accruals [Abstract]
Accounts Payable and Accrued Liabilities	Accounts payable and accrued liabilities consisted of the following, in thousands: June 30, 2018 December 31, 2017 Accounts payable $ 1,755 $ 1,248 Accrued research and development expenses 5,242 3,852 Accrued compensation and benefits 1,563 2,345 Other accrued expenses 770 839 Total accounts payable and accrued expenses $ 9,330 $ 8,284

Equity Incentive Plan (Tables)

Equity Incentive Plan (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Share-based Compensation Expense	The following table summarizes share-based compensation expense for all share-based compensation arrangements, in thousands: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Research and development $ 1,369 $ 678 $ 2,808 $ 1,266 General and administrative 867 352 1,607 658 Total share-based compensation expense $ 2,236 $ 1,030 $ 4,415 $ 1,924 Restricted stock awards: Employee $ 33 $ 33 $ 66 $ 66 Nonemployee 798 445 1,799 828 Total $ 831 $ 478 $ 1,865 $ 894 Stock options: Employee $ 1,349 $ 530 $ 2,429 $ 989 Nonemployee 50 22 115 41 Total $ 1,399 $ 552 $ 2,544 $ 1,030 Employee stock purchase plan: Employee $ 6 $ — $ 6 $ — Total $ 6 $ — $ 6 $ —

Summary of Significant Accoun20

Summary of Significant Accounting Policies - Summary of Number of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Detail) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	3,333	3,635	3,333	3,635
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	3,097	2,214	3,097	2,214
Unvested Restricted Stock Awards
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	202	1,387	202	1,387
Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	34	34	34	34

Investments - Investments Measu

Investments - Investments Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Schedule Of Available For Sale Securities [Line Items]
Short-term investments	$ 108,227	$ 81,712	[1]
Fair Value Measurements on Recurring Basis
Schedule Of Available For Sale Securities [Line Items]
Cash equivalents, Amortized Cost	15,314	8,841
Cash equivalents, Fair Value	15,314	8,841
Short-term investments, Amortized Cost	108,325	81,761
Short-term investments, Unrealized Gains	1
Short-term investments, Unrealized Losses	(99)	(49)
Short-term investments	108,227	81,712
Cash equivalents and Short-term investments, Amortized Cost	123,639	90,602
Cash equivalents and Short-term investments, Fair Value	$ 123,541	$ 90,553
Fair Value Measurements on Recurring Basis | Money Market Funds
Schedule Of Available For Sale Securities [Line Items]
Maturities (years)	1 or less	1 or less
Cash equivalents, Amortized Cost	$ 11,317	$ 5,848
Cash equivalents, Fair Value	$ 11,317	$ 5,848
Fair Value Measurements on Recurring Basis | Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Maturities (years)	1 or less	1 or less
Cash equivalents, Amortized Cost	$ 3,997	$ 2,993
Cash equivalents, Fair Value	$ 3,997	$ 2,993
Maturities (years)	1 or less	1 or less
Short-term investments, Amortized Cost	$ 47,281	$ 50,929
Short-term investments	$ 47,281	$ 50,929
Fair Value Measurements on Recurring Basis | U.S. Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Maturities (years)	2 or less	2 or less
Short-term investments, Amortized Cost	$ 49,620	$ 22,929
Short-term investments, Unrealized Gains	1
Short-term investments, Unrealized Losses	(85)	(42)
Short-term investments	$ 49,536	$ 22,887
Fair Value Measurements on Recurring Basis | Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Maturities (years)	1 or less	1 or less
Short-term investments, Amortized Cost	$ 11,424	$ 7,903
Short-term investments, Unrealized Losses	(14)	(7)
Short-term investments	$ 11,410	$ 7,896
[1]	The balance sheet data at December 31, 2017 has been derived from audited financial statements at that date. It does not include, however, all of the information and notes required by U.S. generally accepted accounting principles for complete financial statements.

Investments - Additional Inform

Investments - Additional Information (Detail)	3 Months Ended	6 Months Ended
	Jun. 30, 2018USD ($)	Jun. 30, 2018USD ($)
Investments All Other Investments [Abstract]
Available-for-sale securities, realized gains or losses	$ 0	$ 0
Marketable securities gross unrealized loss positions for less than twelve months	51,000,000	$ 51,000,000
Short-term investments maturities, description		As of June 30, 2018, $93.4 million of our short-term investments had maturities less than one year, and $14.8 million had maturities between one to two years.
Short-term investments with maturities less than one year	93,400,000	$ 93,400,000
Short-term investments with maturities between one to two years	$ 14,800,000	$ 14,800,000

Fair Value Measurements - Fair

Fair Value Measurements - Fair Values of Investment Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	$ 108,227	$ 81,712	[1]
Fair Value Measurements on Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	15,314	8,841
Short-term investments	108,227	81,712
Cash equivalents and short-term investments	123,541	90,553
Fair Value Measurements on Recurring Basis | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	11,317	5,848
Short-term investments	49,536	22,887
Cash equivalents and short-term investments	60,853	28,735
Fair Value Measurements on Recurring Basis | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	3,997	2,993
Short-term investments	58,691	58,825
Cash equivalents and short-term investments	62,688	61,818
Fair Value Measurements on Recurring Basis | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	11,317	5,848
Fair Value Measurements on Recurring Basis | Money Market Funds | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	11,317	5,848
Fair Value Measurements on Recurring Basis | Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	3,997	2,993
Short-term investments	47,281	50,929
Fair Value Measurements on Recurring Basis | Commercial Paper | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	3,997	2,993
Short-term investments	47,281	50,929
Fair Value Measurements on Recurring Basis | U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	49,536	22,887
Fair Value Measurements on Recurring Basis | U.S. Treasury Securities | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	49,536	22,887
Fair Value Measurements on Recurring Basis | Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	11,410	7,896
Fair Value Measurements on Recurring Basis | Corporate Debt Securities | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	$ 11,410	$ 7,896
[1]	The balance sheet data at December 31, 2017 has been derived from audited financial statements at that date. It does not include, however, all of the information and notes required by U.S. generally accepted accounting principles for complete financial statements.

Accounts Payable and Accrued 24

Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Accounts payable	$ 1,755	$ 1,248
Accrued research and development expenses	5,242	3,852
Accrued compensation and benefits	1,563	2,345
Other accrued expenses	770	839
Total accounts payable and accrued expenses	$ 9,330	$ 8,284	[1]
[1]	The balance sheet data at December 31, 2017 has been derived from audited financial statements at that date. It does not include, however, all of the information and notes required by U.S. generally accepted accounting principles for complete financial statements.

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	Feb. 28, 2018	Jul. 31, 2018	Mar. 31, 2018	Jan. 31, 2018	Jun. 30, 2018	Jun. 30, 2017
Stockholders' Equity Note [Abstract]
Proceeds from issuance of common stock, net					$ 57,650,000	$ 159,000
Subsequent Event
Stockholders' Equity Note [Abstract]
Common stock, shares issued		4,600,000
Proceeds from issuance of common stock, net		$ 74,500,000
Common stock, issued price per share		$ 16.75
Cowen and Company, LLC | At-The-Market Facility
Stockholders' Equity Note [Abstract]
Common stock, shares issued				3,136,722
Common stock weighted average price per share				$ 18.85
Proceeds from issuance of common stock, net				$ 57,700,000
Proceeds from issuance of common stock, gross				$ 59,300,000
Cowen and Company, LLC | At-The-Market Facility | Maximum
Stockholders' Equity Note [Abstract]
Aggregate offering price	$ 100,000,000		$ 160,000,000

Equity Incentive Plan - Summary

Equity Incentive Plan - Summary of Share-based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	$ 2,236	$ 1,030	$ 4,415	$ 1,924
Research and development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	1,369	678	2,808	1,266
General and administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	867	352	1,607	658
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	831	478	1,865	894
Employee	33	33	66	66
Nonemployee	798	445	1,799	828
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	1,399	552	2,544	1,030
Nonemployee	50	22	115	41
Employee	1,349	$ 530	2,429	$ 989
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	6		6
Employee	$ 6		$ 6

Equity Incentive Plan - Additio

Equity Incentive Plan - Additional Information (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized Expense	$ 15.6
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized Expense	$ 0.1
Weighted average service period	2 months 12 days
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average service period	2 years 8 months 12 days

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($)	Apr. 30, 2016	Oct. 01, 2014	Apr. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Accounts receivable, related party				$ 230,000		$ 230,000		$ 216,000	[1]
Research and development, related party				377,000	$ 494,000	676,000	$ 787,000
Accounts payable and accrued expenses, related party				437,000		$ 437,000		216,000	[1]
Araxes Pharma LLC
Related Party Transaction [Line Items]
Asset purchase agreement milstone payment					200,000		200,000
Araxes Pharma LLC | Management Fees | Management Service
Related Party Transaction [Line Items]
Management Fee, Description						Effective April 2018, we amended our management services agreement with Araxes. Under the amendment, Araxes pays us a fixed fee of $60,000 per month for management services, which is reduced from the fixed fee of $65,000 per month.
Research and development services reimbursement, description						In addition, the agreement allows for Araxes to reimburse us an amount equal to the number of full time equivalents, or FTE, performing research and development services for Araxes, at an annual FTE rate of approximately $367,000, plus actual expenses as reasonably incurred. The initial term of this agreement expired on December 31, 2015 but, pursuant to the terms of the agreement, renews automatically for additional consecutive one-year periods. The agreement may be terminated by either party with a notice of at least 30 days prior to the expiration of the then-renewal term.
Service Agreement for research and development, FTE rate	$ 367,000
Agreement expiration date		Dec. 31, 2015
Agreement termination notice period		30 days
Amount received on research and development services				100,000	100,000	$ 100,000	200,000
Accounts receivable, related party				200,000		200,000		200,000
Araxes Pharma LLC | Management Service Agreement, Fixed | Management Fees
Related Party Transaction [Line Items]
Management service agreement, fixed			$ 60,000			$ 65,000
Wellspring Biosciences Inc | Services Agreement
Related Party Transaction [Line Items]
Research and development expense payment, description						We have a services agreement with Wellspring pursuant to which we pay Wellspring for research and development services provided to us in an amount equal to the number of FTE’s performing the services, at an annual FTE rate of $400,000, plus actual expenses as reasonably incurred. The initial term of this services agreement expired on December 31, 2015 but, pursuant to the terms of the agreement, renews automatically for additional consecutive one-year periods. The agreement may be terminated by either party with a notice of at least 30 days prior to the expiration of the then-renewal term.
Agreement expiration date		Dec. 31, 2015
Agreement termination notice period		30 days
Research and development services expense at full time equivalents rate		$ 400,000
Research and development, related party				400,000	300,000	$ 700,000	700,000
Accounts payable and accrued expenses, related party				400,000		400,000		$ 200,000
Wellspring Biosciences Inc | Sublease
Related Party Transaction [Line Items]
Rent expense related to office space sublease				$ 100,000	$ 100,000	$ 200,000	$ 100,000
Sublease agreement description						We subleased office space in La Jolla, California from Wellspring Biosciences, Inc., or Wellspring, a wholly owned subsidiary of Araxes pursuant to a sublease agreement that expired in June 2017. In December 2016, we entered into a new sublease agreement with Wellspring for office space in San Diego, California, or New Sublease.
Wellspring Biosciences Inc | San Diego California
Related Party Transaction [Line Items]
Sublease expiration date						Oct. 31, 2019
[1]	The balance sheet data at December 31, 2017 has been derived from audited financial statements at that date. It does not include, however, all of the information and notes required by U.S. generally accepted accounting principles for complete financial statements.