Xencor (XNCR) 10-Q 5 Aug 20 2020 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2020	Jul. 30, 2020
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 2020
Entity File Number	001-36182
Entity Registrant Name	Xencor Inc
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-1622502
Entity Address, Address Line One	111 West Lemon Avenue
Entity Address, City or Town	Monrovia
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	91016
City Area Code	626
Local Phone Number	305-5900
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	XNCR
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		57,242,886
Entity Central Index Key	0001326732
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 109,534	$ 50,312
Marketable securities	474,114	479,470
Equity securities	2,611
Accounts receivable	8,925	21,574
Income tax receivable	804	502
Prepaid expenses and other current assets	7,398	6,547
Total current assets	603,386	558,405
Property and equipment, net	16,239	15,805
Patents, licenses, and other intangible assets, net	15,162	14,421
Marketable securities - long term	1,145	71,526
Income tax receivable		402
Other assets	8,788	9,691
Total assets	644,720	670,250
Current liabilities
Accounts payable	10,513	10,189
Accrued expenses	9,157	8,995
Lease liabilities	2,094	2,169
Deferred revenue	44,685	45,205
Total current liabilities	66,449	66,558
Lease liabilities, net of current portion	7,626	8,565
Deferred revenue, net of current portion		1,926
Total liabilities	74,075	77,049
Commitments and contingencies
Stockholders' equity
Preferred stock, $0.01 par value: 10,000,000 authorized shares; -0- issued and outstanding shares at June, 2020 and December 31, 2019
Common stock, $0.01 par value: 200,000,000 authorized shares at June 30, 2020 and December 31, 2019; 57,214,253 issued and outstanding at June 30, 2020 and 56,902,301 issued and outstanding at December 31, 2019	572	569
Additional paid-in capital	908,084	887,873
Accumulated other comprehensive income	1,483	1,161
Accumulated deficit	(339,494)	(296,402)
Total stockholders' equity	570,645	593,201
Total liabilities and stockholders' equity	$ 644,720	$ 670,250

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
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 (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	57,214,253	56,902,301
Common stock, shares outstanding	57,214,253	56,902,301

Statements of Comprehensive Inc

Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue
Collaborations, licenses, milestones, and royalties	$ 13,089	$ 19,485	$ 45,474	$ 131,424
Operating expenses
Research and development	43,458	33,299	77,401	61,481
General and administrative	7,231	5,758	14,449	11,270
Total operating expenses	50,689	39,057	91,850	72,751
Income (loss) from operations	(37,600)	(19,572)	(46,376)	58,673
Other income (expenses)
Interest income, net	2,090	3,615	5,129	6,501
Other income (expense), net	492	(27)	(1,845)	(212)
Total other income, net	2,582	3,588	3,284	6,289
Net income (loss) before income tax expense	(35,018)	(15,984)	(43,092)	64,962
Income tax expense		50		950
Net income (loss)	(35,018)	(16,034)	(43,092)	64,012
Other comprehensive income
Net unrealized gain on marketable securities	427	1,284	322	2,600
Comprehensive income (loss)	$ (34,591)	$ (14,750)	$ (42,770)	$ 66,612
Net income (loss) per share attributable to common stockholders:
Basic net income (loss) (in dollars per share)	$ (0.61)	$ (0.28)	$ (0.76)	$ 1.14
Diluted net income (loss) (in dollars per share)	$ (0.61)	$ (0.28)	$ (0.76)	$ 1.10
Weighted average shares used to compute net income (loss) per share attributable to common stockholders:
Basic (in shares)	57,059,610	56,399,255	57,003,162	56,351,377
Diluted (in shares)	57,059,610	56,399,255	57,003,162	58,042,819

Statement of Stockholders' Equi

Statement of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Balance at Dec. 31, 2018	$ 563	$ 845,366	$ (971)	$ (323,277)	$ 521,681
Balance (in shares) at Dec. 31, 2018	56,279,542
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock awards	$ 1	666			667
Issuance of common stock upon exercise of stock awards (in shares)	58,536
Issuance of restricted stock units (in shares)	11,311
Comprehensive income (loss)			1,316	80,045	81,361
Stock-based compensation expense		5,856			5,856
Balance at Mar. 31, 2019	$ 564	851,888	345	(243,232)	609,565
Balance (in shares) at Mar. 31, 2019	56,349,389
Balance at Dec. 31, 2018	$ 563	845,366	(971)	(323,277)	521,681
Balance (in shares) at Dec. 31, 2018	56,279,542
Increase (Decrease) in Stockholders' Equity
Comprehensive income (loss)					66,612
Balance at Jun. 30, 2019	$ 565	865,163	1,629	(259,266)	608,091
Balance (in shares) at Jun. 30, 2019	56,529,398
Balance at Mar. 31, 2019	$ 564	851,888	345	(243,232)	609,565
Balance (in shares) at Mar. 31, 2019	56,349,389
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock awards	$ 1	3,238			3,239
Issuance of common stock upon exercise of stock awards (in shares)	143,504
Issuance of common stock under the Employee Stock Purchase Plan		734			734
Issuance of common stock under the Employee Stock Purchase Plan (in shares)	36,505
Comprehensive income (loss)			1,284	(16,034)	(14,750)
Stock-based compensation expense		9,303			9,303
Balance at Jun. 30, 2019	$ 565	865,163	1,629	(259,266)	608,091
Balance (in shares) at Jun. 30, 2019	56,529,398
Balance at Dec. 31, 2019	$ 569	887,873	1,161	(296,402)	593,201
Balance (in shares) at Dec. 31, 2019	56,902,301
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock awards	$ 1	1,470			1,471
Issuance of common stock upon exercise of stock awards (in shares)	79,930
Issuance of restricted stock units (in shares)	19,022
Comprehensive income (loss)			(105)	(8,074)	(8,179)
Stock-based compensation expense		6,512			6,512
Balance at Mar. 31, 2020	$ 570	895,855	1,056	(304,476)	593,005
Balance (in shares) at Mar. 31, 2020	57,001,253
Balance at Dec. 31, 2019	$ 569	887,873	1,161	(296,402)	593,201
Balance (in shares) at Dec. 31, 2019	56,902,301
Increase (Decrease) in Stockholders' Equity
Comprehensive income (loss)					(42,770)
Balance at Jun. 30, 2020	$ 572	908,084	1,483	(339,494)	570,645
Balance (in shares) at Jun. 30, 2020	57,214,253
Balance at Mar. 31, 2020	$ 570	895,855	1,056	(304,476)	593,005
Balance (in shares) at Mar. 31, 2020	57,001,253
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock awards	$ 2	3,273			3,275
Issuance of common stock upon exercise of stock awards (in shares)	181,856
Issuance of common stock under the Employee Stock Purchase Plan		725			725
Issuance of common stock under the Employee Stock Purchase Plan (in shares)	28,344
Issuance of restricted stock units (in shares)	2,800
Comprehensive income (loss)			427	(35,018)	(34,591)
Stock-based compensation expense		8,231			8,231
Balance at Jun. 30, 2020	$ 572	$ 908,084	$ 1,483	$ (339,494)	$ 570,645
Balance (in shares) at Jun. 30, 2020	57,214,253

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities
Net income (loss)	$ (43,092)	$ 64,012
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	2,816	2,003
Accretion of discount on marketable securities	(838)	(1,876)
Stock-based compensation	14,743	15,159
Abandonment of capitalized intangible assets	167	90
Equity received in connection with license agreement	(4,589)
Change in fair value of equity security	1,978
Loss on disposal of assets	5	5
Gain on sale of marketable securities available-for-sale	(153)
Changes in operating assets and liabilities:
Accounts receivable	12,649	122
Interest receivable	914	(154)
Prepaid expenses and other assets	(843)	(932)
Accounts payable	324	5,197
Accrued expenses	162	(3,436)
Income taxes	91	1,604
Lease liabilities and right of use (ROU) assets	(110)	(65)
Deferred revenue	(2,446)	8,699
Net cash provided by (used in) operating activities	(18,222)	90,428
Cash flows from investing activities
Purchase of marketable securities	(302,319)	(244,499)
Purchase of intangible assets	(1,467)	(2,164)
Purchase of property and equipment	(2,695)	(1,867)
Proceeds from maturities of marketable securities	378,454	159,773
Net cash provided by (used in) investing activities	71,973	(88,757)
Cash flows from financing activities
Proceeds from issuance of common stock upon exercise of stock awards	4,746	3,906
Proceeds from issuance of common stock under the Employee Stock Purchase Plan	725	734
Net cash provided by financing activities	5,471	4,640
Net increase in cash and cash equivalents	59,222	6,311
Cash and cash equivalents, beginning of period	50,312	26,246
Cash and cash equivalents, end of period	109,534	32,557
Cash paid during the period for:
Interest	11	7
Income taxes		150
Supplemental disclosures of non-cash investing activities
Net unrealized gain on marketable securities	$ 322	$ 2,600

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2020
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	1. Summary of Significant Accounting Policies ​ Basis of Presentation ​ The accompanying unaudited interim financial statements for Xencor, Inc. (the Company, Xencor, we or us) have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information. The financial statements include all adjustments (consisting only of normal recurring adjustments) that the management of the Company believes are necessary for a fair presentation of the periods presented. The preparation of interim financial statements requires the use of management’s estimates and assumptions that affect reported amounts of assets and liabilities at the date of the interim financial statements and the reported revenues and expenditures during the reported periods. These interim financial results are not necessarily indicative of the results expected for the full fiscal year or for any subsequent interim period. ​ The accompanying unaudited interim financial statements and related notes should be read in conjunction with the audited financial statements and notes thereto included in the Company’s 2019 Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on February 25, 2020. ​ Use of Estimates ​ The preparation of interim financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, other comprehensive gain (loss) and the related disclosures. On an ongoing basis, management evaluates its estimates, including estimates related to its accrued clinical trial and manufacturing development expenses, stock-based compensation expense, intangible assets and related amortization. Significant estimates in these interim financial statements include estimates made for royalties and accrued research and development expenses, stock-based compensation expenses, intangible assets and related amortization, estimated standalone selling price of performance obligations, the likelihood of recognizing variable consideration, and recoverability of deferred tax assets. ​ Intangible Assets ​ The Company maintains definite-lived intangible assets related to certain capitalized costs of acquired licenses and third-party costs incurred in establishing and maintaining its intellectual property rights to its platform technologies and development candidates. These assets are amortized over their useful lives, which are estimated to be the remaining patent life or the contractual term of the license. The straight-line method is used to record amortization expense. The Company assesses its intangible assets for impairment if indicators are present or changes in circumstances suggest that impairment may exist. There were no impairment charges recorded for the three and six months ended June 30, 2020 and 2019. ​ The Company capitalizes certain in-process intangible assets that are then abandoned when they are no longer pursued or used in current research activities. There was no material abandonment of in-process intangible assets during the three and six months ended June 30, 2020 and 2019. ​ Marketable and Equity Securities ​ The Company has an investment policy that includes guidelines on acceptable investment securities, minimum credit quality, maturity parameters, and concentration and diversification. The Company invests its excess cash primarily in marketable debt securities issued by investment grade institutions. ​ The Company considers its marketable debt securities to be available-for-sale and does not intend to sell these securities, and it is not more likely than not that the Company will be required to sell the securities before recovery of the amortized cost basis. These assets are carried at fair value and any impairment losses and recoveries related to the underlying issuer’s credit standing are recognized within other income (expense), while non-credit related impairment losses and recoveries are recognized within accumulated other comprehensive income (loss). There were no impairment losses or recoveries recorded for the three and six months ended June 30, 2020 and 2019. Accrued interest on marketable debt securities is included in marketable securities’ carrying value. Each reporting period, the Company reviews its portfolio of marketable debt securities, using both quantitative and qualitative factors, to determine if each security’s fair value has declined below its amortized cost basis. ​ The Company also has an investment in an equity security that is carried at fair value with changes in fair value recognized within other income (expense). For equity securities with a readily determinable fair value, the Company remeasures these equity investments at each reporting period until such time that the investment is sold or disposed. If the Company sells an investment, any realized gains and losses on the sale of the securities will be recognized within other income (expense) in the Statement of Comprehensive Income (Loss) in the period of sale. ​ Recent Accounting Pronouncements ​ Pronouncements Adopted in 2020 ​ Effective January 1, 2020, the Company adopted ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, as well as ASU No, 2018-19, Codification Improvements to Topic 326, Financial Instruments – Credit Losses. The standard amends guidance on reporting credit losses for assets held at amortized cost basis and also provides an available-for-sale (AFS) debt security impairment model that is a modified version of the other-than-temporary-impairment (OTTI) model. The AFS debt security impairment model no longer allows consideration of the length of time during which the fair value has been less than its amortized cost when determining whether a credit loss exists. The adoption of this standard did not have any impact on the Company’s financial statements. ​ Effective January 1, 2020, the Company adopted ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement, which modifies the disclosures for transfers between Level 1 and Level 2 of the fair value hierarchy, modifies the Level 3 disclosure requirements for non-public entities and requires additional disclosure for Level 3 fair value hierarchy. The adoption of this standard did not have any impact on the Company’s financial statements. ​ Effective January 1, 2020, the Company adopted ASU No. 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606, which provides guidance on how to assess whether certain transactions between collaborative arrangement participants should be accounted for within the revenue recognition standard. The adoption of this standard did not have any impact on the Company’s financial statements. ​ Pronouncements Not Yet Effective ​ In December 2019, the Financial Accounting Standards Board (FASB) issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ​ In January 2020, the FASB issued ASU No. 2020-01, which clarifies that a company should consider observable transactions that require a company to either apply or discontinue the equity method of accounting under Topic 323, Investment – Equity Method and Joint Ventures, for the purposes of applying the measurement alternative in accordance with Topic 321 immediately before applying or upon discontinuing the equity method. The amendment is effective for fiscal years beginning after December 15, 2020. The Company does not anticipate that the standard will have a significant impact on its financial statements. ​ There have been no other material changes to the significant accounting policies previously disclosed in the Company’s 2019 Annual Report on Form 10-K. ​

Fair Value of Financial Instrum

Fair Value of Financial Instruments	6 Months Ended
	Jun. 30, 2020
Fair Value of Financial Instruments
Fair Value of Financial Instruments	2. Fair Value of Financial Instruments ​ Financial instruments included in the financial statements include cash equivalents, marketable securities, accounts receivable, accounts payable and accrued expenses. Marketable securities and cash equivalents are carried at fair value. The fair value of the other financial instruments closely approximates their fair value due to their short-term maturities. ​ The Company accounts for recurring and non-recurring fair value measurements in accordance with FASB Accounting Standards Codification ASC 820, Fair Value Measurements and Disclosures ​ Level 1— ​ Level 2— ​ Level 3— ​ The Company measures the fair value of financial assets using the highest level of inputs that are reasonably available as of the measurement date. The assets recorded at fair value are classified within the hierarchy as follows for the periods reported (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2020 ​ December 31, 2019 ​ Total ​ ​ ​ ​ Total ​ ​ ​ ​ ​ ​ Fair Value ​ Level 1 ​ Level 2 ​ Fair Value ​ Level 1 ​ Level 2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money Market Funds ​ $ 103,231 ​ $ 103,231 ​ $ — ​ $ 32,009 ​ $ 32,009 ​ $ — Corporate Securities ​ ​ 267,542 ​ ​ — ​ ​ 267,542 ​ ​ 281,751 ​ ​ — ​ ​ 281,751 Government Securities ​ ​ 207,717 ​ ​ — ​ ​ 207,717 ​ ​ 269,245 ​ ​ — ​ ​ 269,245 Equity Securities with Readily Determinable Fair Value ​ ​ 2,611 ​ ​ 2,611 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ $ 581,101 ​ $ 105,842 ​ $ 475,259 ​ $ 583,005 ​ $ 32,009 ​ $ 550,996 ​ Our policy is to record transfers of assets between Level 1 and Level 2 at their fair values as of the end of each reporting period, consistent with the date of the determination of fair value. During the three and six months ended June 30, 2020 and 2019, there were no transfers between Level 1 and Level 2. The Company does not have any Level 3 assets or liabilities.

Net Income (Loss) Per Share

Net Income (Loss) Per Share	6 Months Ended
	Jun. 30, 2020
Net Income (Loss) Per Share
Net Income (Loss) Per Share	3. Net Income (Loss) Per Share ​ We compute basic net income (loss) per common share by dividing the net income (loss) attributable to common stockholders by the weighted-average number of common shares outstanding during the period without consideration of common stock equivalents. Diluted net income (loss) per share is computed by dividing the net income (loss) attributable to common stockholders by the weighted-average number of common stock equivalents outstanding for the period. The treasury stock method is used to determine the dilutive effect of the Company’s stock option grants, employee stock purchase plan (ESPP) and restricted stock units (RSUs). Potentially dilutive securities consisting of stock issuable under options, ESPP and RSUs are not included in the per common share calculation in periods when the inclusion of such shares would have an antidilutive effect. ​ Basic and diluted net income (loss) per common share is computed as follows (in thousands except share and per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended Six Months Ended ​ ​ June 30, ​ June 30, ​ 2020 2019 2020 2019 ​ ​ (in thousands, except share and per share data) Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) attributable to common stockholders ​ $ (35,018) ​ $ (16,034) ​ $ (43,092) ​ $ 64,012 Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average common shares outstanding used in computing basic net income (loss) ​ 57,059,610 ​ 56,399,255 ​ ​ 57,003,162 ​ ​ 56,351,377 Effect of dilutive securities ​ ​ — ​ ​ — ​ ​ — ​ ​ 1,691,442 Weighted-average common shares outstanding used in computing diluted net income (loss) ​ ​ 57,059,610 ​ ​ 56,399,255 ​ ​ 57,003,162 ​ ​ 58,042,819 Basic net income (loss) per common share ​ $ (0.61) ​ $ (0.28) ​ $ (0.76) ​ $ 1.14 Diluted net income (loss) per common share ​ $ (0.61) ​ $ (0.28) ​ $ (0.76) ​ $ 1.10 ​ For the three and six months ended June 30, 2020, and the three months ended June 30, 2019, all outstanding potentially dilutive securities have been excluded from the calculation of diluted net loss per common share as the effect of including such securities would have been antidilutive. For the six months ended June 30, 2019, potentially dilutive securities consisting of 1,173,829 shares of stock awards are excluded from the calculation for the same period because the inclusion of such shares would have had an antidilutive effect.

Comprehensive Income

Comprehensive Income	6 Months Ended
	Jun. 30, 2020
Comprehensive Income
Comprehensive Income	4. Comprehensive Income ​ Comprehensive income is comprised of net income (loss) and other comprehensive income (loss). For the three and six months ended June 30, 2020 and 2019, the only component of other comprehensive income is net unrealized gain on marketable securities. There were no material reclassifications out of accumulated other comprehensive income (loss) during the three and six months ended June 30, 2020 and 2019.

Marketable and Equity Securitie

Marketable and Equity Securities	6 Months Ended
	Jun. 30, 2020
Marketable and Equity Securities
Marketable and Equity Securities	5. Marketable and Equity Securities ​ The Company’s marketable debt securities held as of June 30, 2020 and December 31, 2019 are summarized below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ Amortized Unrealized ​ Unrealized ​ June 30, 2020 ​ Cost ​ Gains ​ Losses ​ Fair Value (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money Market Funds ​ $ 103,231 ​ $ — ​ $ — ​ $ 103,231 Corporate Securities ​ ​ 266,756 ​ ​ 786 ​ ​ — ​ ​ 267,542 Government Securities ​ ​ 207,010 ​ ​ 710 ​ ​ (3) ​ ​ 207,717 ​ ​ $ 576,997 ​ $ 1,496 ​ $ (3) ​ $ 578,490 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported as ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 103,231 Marketable securities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 475,259 Total investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 578,490 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ Amortized Unrealized ​ Unrealized ​ December 31, 2019 ​ Cost ​ Gains ​ Losses ​ Fair Value (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money Market Funds ​ $ 32,009 ​ $ — ​ $ — ​ $ 32,009 Corporate Securities ​ ​ 281,586 ​ ​ 195 ​ ​ (30) ​ ​ 281,751 Government Securities ​ ​ 268,239 ​ ​ 1,006 ​ ​ — ​ ​ 269,245 ​ ​ $ 581,834 ​ $ 1,201 ​ $ (30) ​ $ 583,005 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported as ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 32,009 Marketable securities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 550,996 Total investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 583,005 ​ The maturities of the Company’s marketable debt securities are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized Estimated June 30, 2020 ​ Cost ​ Fair Value (in thousands) ​ ​ ​ ​ ​ ​ Mature in one year or less ​ $ 472,639 ​ $ 474,114 Mature within two years ​ ​ 1,127 ​ ​ 1,145 ​ ​ $ 473,766 ​ $ 475,259 ​ ​ The unrealized losses on available-for-sale investments and their related fair values as of June 30, 2020 and December 31, 2019 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less than 12 months ​ 12 months or greater ​ ​ ​ ​ ​ Unrealized ​ ​ ​ ​ Unrealized June 30, 2020 ​ Fair value ​ losses ​ Fair value ​ losses (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Government Securities ​ ​ 49,973 ​ ​ (3) ​ ​ — ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less than 12 months ​ 12 months or greater ​ ​ ​ ​ ​ Unrealized ​ ​ ​ ​ Unrealized December 31, 2019 ​ Fair value ​ losses ​ Fair value ​ losses (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate Securities ​ $ 46,303 ​ $ (24) ​ $ 13,992 ​ $ (6) ​ The unrealized losses from the listed securities are primarily due to a change in the interest rate environment and not a change in the credit quality of the securities. ​ In connection with the Aimmune Agreement (as defined below) which we entered in February 2020, the Company received shares of Aimmune common stock which are classified as equity securities with a readily determinable fair value as of June 30, 2020. The Company recorded $0.3 million of unrealized gain and $2.0 million of unrealized loss related to these securities in other income (expense) during the three and six months ended June 30, 2020. We did not hold any equity securities in our investment portfolio during the year ended December 31, 2019.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2020
Stock-Based Compensation
Stock-Based Compensation	6. Stock Based Compensation ​ Our Board of Directors (the Board) and the requisite stockholders previously approved the 2010 Equity Incentive Plan (the 2010 Plan). In October 2013, the Board approved the 2013 Equity Incentive Plan (the 2013 Plan) and in November 2013 our stockholders approved the 2013 Plan which became effective as of December 3, 2013. As of December 2, 2013, we suspended the 2010 Plan and no additional awards may be granted under the 2010 Plan. Any shares of common stock covered by awards granted under the 2010 Plan that terminate after December 2, 2013 by expiration, forfeiture, cancellation or other means without the issuance of such shares will be added to the 2013 Plan reserve. ​ As of June 30, 2020, the total number of shares of common stock available for issuance under the 2013 Plan is 12,116,313, which includes 2,684,456 shares of common stock that were available for issuance under the 2010 Plan as of the effective date of the 2013 Plan. Unless otherwise determined by the Board, beginning January 1, 2014, and continuing until the expiration of the 2013 Plan, the total number of shares of common stock available for issuance under the 2013 Plan will automatically increase annually on January 1 of each year by 4% of the total number of issued and outstanding shares of common stock as of December 31 of the immediate preceding year. Pursuant to approval by the Board, the total number of shares of common stock available for issuance under the 2013 Plan was increased by 1,138,046 shares on January 1, 2020. As of June 30, 2020, a total of 10,327,214 shares of common stock subject to options have been granted under the 2013 Plan. ​ In November 2013, the Board and our stockholders approved the 2013 Employee Stock Purchase Plan (ESPP), which became effective as of December 5, 2013. We have reserved a total of 581,286 shares of common stock for issuance under the ESPP. Unless otherwise determined by the Board, beginning on January 1, 2014, and continuing until the expiration of the ESPP, the total number of shares of common stock available for issuance under the ESPP will automatically increase annually on January 1 by the lesser of (i) 1% of the total number of issued and outstanding shares of common stock as of December 31 of the immediately preceding year, or (ii) 621,814 shares of common stock. Pursuant to approval by our Board of Directors, there was no increase in the number of authorized shares in the ESPP from 2015 to 2020. As of June 30, 2020, we have issued a total of 445,621 shares of common stock under the ESPP. ​ During the six months ended June 30, 2020, the Company awarded 305,794 Restricted Stock Units (RSUs) to certain employees. Vesting of these awards is in three equal annual installments and is contingent on continued service to the Company. The fair value of these awards is determined based on the intrinsic value of the stock on the date of grant and will be recognized as stock-based compensation expense over the requisite service period. As of June 30, 2020, we have granted a total of 411,293 shares of common stock subject to RSUs. ​ Total employee, director and non-employee stock-based compensation expense recognized for the three and six months ended June 30, 2020 and 2019 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended Six Months Ended ​ ​ June 30, June 30, ​ 2020 2019 2020 2019 General and administrative ​ $ 2,804 ​ $ 2,008 ​ $ 5,095 ​ $ 3,862 Research and development ​ 5,427 ​ 7,295 ​ 9,648 ​ 11,297 ​ ​ $ 8,231 ​ $ 9,303 ​ $ 14,743 ​ $ 15,159 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ ​ 2020 2019 ​ 2020 2019 Stock options ​ $ 6,667 ​ $ 8,946 ​ $ 12,549 ​ $ 14,470 ESPP ​ ​ 213 ​ ​ 195 ​ ​ 407 ​ ​ 413 Restricted stock units ​ ​ 1,351 ​ ​ 162 ​ ​ 1,787 ​ ​ 276 ​ ​ $ 8,231 ​ $ 9,303 ​ $ 14,743 ​ $ 15,159 ​ The following table summarizes option activity under our stock plans and related information: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Weighted ​ ​ ​ ​ ​ ​ Average Average ​ ​ ​ ​ Number of ​ Exercise Remaining ​ Aggregate ​ ​ Shares Subject ​ Price Contractual ​ Intrinsic ​ ​ to Outstanding ​ (Per Term ​ Value ​ ​ Options ​ Share) (in years) ​ (in thousands) Balances at December 31, 2019 7,174,319 ​ $ 24.03 ​ ​ 7.32 ​ ​ ​ Options granted 1,433,699 ​ $ 32.10 ​ ​ ​ ​ ​ ​ Options forfeited (115,261) ​ $ 31.28 ​ ​ ​ ​ ​ ​ Options exercised (261,786) ​ $ 18.13 ​ ​ ​ ​ ​ ​ Balances at June 30, 2020 8,230,971 ​ $ 25.52 ​ ​ 7.33 ​ $ 65,362 Exercisable ​ 4,587,110 ​ $ 20.28 ​ ​ 6.10 ​ $ 58,544 ​ We calculate the intrinsic value as the difference between the exercise price of the options and the closing price of common stock of $32.39 per share as of June 30, 2020. ​ Weighted-average fair value of options granted during the six-month periods ended June 30, 2020 and 2019 were $16.44 and $20.74 per share, respectively. There were 1,700,583 options granted during the six-month period ended June 30, 2019. We estimated the fair value of each stock option using the Black-Scholes option-pricing model based on the date of grant of such stock option with the following weighted average assumptions for the three and six months ended June 30, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options ​ Options ​ ​ Three Months Ended ​ Six Months Ended ​ ​ ​ June 30, ​ June 30, ​ 2020 2019 2020 2019 Expected term (years) ​ 5.7 5.9 ​ 6.2 6.0 ​ Expected volatility ​ 56.1 % 61.3 % 54.3 % 61.3 % Risk-free interest rate ​ 0.41 % 2.07 % 0.84 % 2.43 % Expected dividend yield ​ — % — % — % — % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ESPP ​ ESPP ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ 2020 2019 2020 2019 Expected term (years) 0.5 - 2.0 0.5 - 2.0 ​ 0.5 - 2.0 0.5 - 2.0 ​ Expected volatility ​ 50.8 - 62.6 % 55.0 - 71.4 % 50.8 - 62.6 % 55.0 - 71.4 % Risk-free interest rate 0.18 - 1.65 % 1.47 - 2.70 % 0.18 - 1.65 % 1.47 - 2.70 % Expected dividend yield ​ — % — % — % — % ​ As of June 30, 2020, the unamortized compensation expense related to unvested stock options was $59.4 million. The remaining unamortized compensation expense will be recognized over the next 2.8 years. As of June 30, 2020, the unamortized compensation expense under our ESPP was $1.3 million. The remaining unamortized expense will be recognized over the next 1.4 years. ​ The following table summarizes the RSU activity for the six-month period ended June 30, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ Restricted ​ Average Grant ​ ​ Stock ​ Date Fair Value ​ ​ Units ​ (Per unit) ​ ​ ​ ​ ​ ​ Unvested at December 31, 2019 90,006 ​ $ 34.66 Granted 305,794 ​ ​ 31.64 Vested (21,822) ​ ​ 31.91 Forfeited (7,311) ​ ​ 31.47 Unvested at June 30, 2020 366,667 ​ $ 32.37 ​ As of June 30, 2020, the unamortized compensation expense related to unvested RSUs was $10.2 million. The remaining unamortized expense will be recognized over the next 2.3 years.

Leases

Leases	6 Months Ended
	Jun. 30, 2020
Leases
Leases	7. Leases ​ The Company leases office and laboratory space in Monrovia, CA under a lease that expires September 30, 2020; the original lease was a 66-month lease that expired June 2020. In April 2020, the Company entered into an amendment to the lease to extend the term of the lease under the original terms through September 2020. In July 2017, the Company entered into a lease agreement for additional space in the same building with a lease that continues through September 2022, with an option to renew for an additional five years . The Company assesses that it is likely to exercise the option of the lease term extension. The Company also leases office space in San Diego, CA that expired July 2020. The lease includes an option to renew for an additional five years and the Company did not exercise the option to extend this lease. ​ The Company leases additional office space in San Diego, CA through August 2022, with an option to extend for an additional five years . The Company assesses that it is unlikely to exercise the option to extend the lease term. ​ The Company’s lease agreements do not contain any residual value guarantees or restrictive covenants. As of June 30, 2020, the Company did not have additional operating leases that have not yet commenced. ​ The following table reconciles the undiscounted cash flows for the operating leases at June 30, 2020 to the operating lease liabilities recorded on the balance sheet (in thousands): ​ ​ ​ ​ ​ Years ending December 31, ​ ​ For the remainder of 2020 ​ $ 1,297 2021 ​ 2,583 2022 ​ ​ 2,203 2023 ​ ​ 1,347 2024 ​ ​ 1,366 2025 ​ ​ 1,212 Thereafter ​ ​ 1,238 Total undiscounted lease payments ​ ​ 11,246 Less: Imputed interest ​ ​ (1,526) Present value of lease payments ​ $ 9,720 ​ ​ ​ ​ Lease liabilities - short-term ​ $ 2,094 Lease liabilities - long-term ​ ​ 7,626 Total lease liabilities ​ $ 9,720 ​ The following table summarizes lease costs and cash disclosures for the three and six months ended June 30, 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ ​ 2020 2019 ​ 2020 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease cost ​ $ 648 ​ $ 650 ​ $ 1,297 ​ $ 1,299 Variable lease cost ​ ​ 38 ​ ​ 47 ​ ​ 59 ​ ​ 57 Total lease costs ​ $ 686 ​ $ 697 ​ $ 1,356 ​ $ 1,356 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash paid for amounts included in ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ the measurement of lease liabilities ​ $ 566 ​ $ 344 ​ $ 1,123 ​ $ 854 ​ The amendment to the Monrovia, CA lease is a lease modification. Non-cash activities involving ROU assets related to the lease modification were $0.1 million for three and six months ended June 30, 2020. ​ At June 30, 2020, the weighted-average remaining lease term for operating leases was 5.2 years, and the weighted-average discount rate for operating leases is 5.5%

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2020
Commitments and Contingencies
Commitments and Contingencies	8. Commitments and Contingencies ​ From time to time, the Company may be subject to various litigation and related matters arising in the ordinary course of business. The Company does not believe it is currently subject to any material matters where there is at least a reasonable possibility that a material loss may be incurred. ​ The Company is obligated to make future payments to third parties under in-license agreements, including sublicense fees, royalties, and payments that become due and payable on the achievement of certain development and commercialization milestones. As the amount and timing of sublicense fees and the achievement and timing of these milestones are not probable and estimable, such commitments have not been included on the Company’s balance sheet. The Company has also entered into agreements with third-party vendors which will require us to make future payments upon the delivery of goods and services in future periods.

Collaboration and Licensing Agr

Collaboration and Licensing Agreements	6 Months Ended
	Jun. 30, 2020
Collaboration and Licensing Agreements
Collaboration and Licensing Agreements	9. Collaboration and Licensing Agreements ​ The following is a summary description of the material revenue arrangements, including arrangements that generated revenue in the three and six months ended June 30, 2020 and 2019. ​ Genentech In February 2019, the Company entered into a collaboration and license agreement (the Genentech Agreement) with Genentech, Inc. and F. Hoffman-La Roche Ltd (collectively, Genentech) for the development and commercialization of novel IL-15 collaboration products (Collaboration Products), including XmAb24306 (also named RG6323), the Company’s IL-15/IL-15Ra candidate. The Genentech Agreement became effective March 8, 2019. Under the terms of the Genentech Agreement, Genentech received an exclusive worldwide license to XmAb24306 and other Collaboration Products, including any new IL-15 programs identified during the joint research collaboration. Genentech and the Company will jointly collaborate on worldwide development of XmAb24306 and potentially other Collaboration Products with Genentech maintaining all worldwide commercialization rights, subject to the Company having an option to co-promote in the United States. The Company has the right to perform clinical studies of Collaboration Products in combination with other therapeutic agents at its own cost, subject to certain requirements. The Company received a $120.0 million upfront payment and is eligible to receive up to an aggregate of $160.0 million in clinical milestone payments for each Collaboration Product that advances to Phase 3 clinical trials. The Company is also eligible to receive 45% share of net profits for sales of XmAb24306 and other Collaboration Products, while also sharing in net losses at the same percentage rate. The parties will jointly share in development and commercialization costs for all programs designated as a development program under the Genentech Agreement at the same percentage rate, while Genentech will bear launch costs entirely. The initial 45% profit-cost share percent is subject to ratchet down at the Company’s discretion and convertible to a royalty under certain restrictions. Pursuant to the Genentech Agreement, XmAb24306 is designated as a development program and all costs incurred for developing XmAb24306 from March 8, 2019, the effective date of the Genentech Agreement, are being shared with Genentech under the initial cost-sharing percentage of 45%. Pursuant to the Genentech Agreement, the Company and Genentech will conduct joint research activities for a two -year period to identify and discover additional IL-15 candidates developed from the Company’s cytokine and bispecific technologies. The two-year research term may be extended an additional year if both parties agree. The Company and Genentech are each responsible for their own costs in conducting the research activities. The Company is eligible for clinical milestone payments for new Collaboration Products identified from the research efforts. The Company recognized the $111.7 million allocated to the license when it satisfied its performance obligation and transferred the license to Genentech in March 2019. A total of $8.3 million of the transaction price was allocated to the research activities and is being recognized over a period of time through the end of the research term that services are rendered. A total of $0.8 million and $1.5 million of revenue related to the research activities was recognized in the three- and six-month periods ended June 30, 2020, respectively. For the three months ended June 30, 2020 and 2019, the Company recognized $0.8 million and $0.6 million of income, respectively, from the Genentech Agreement. For the six months ended June 30, 2020 and 2019, the Company recognized $1.5 million and $112.5 million of income, respectively. As of June 30, 2020, there is a $1.3 million payable related to cost-sharing development activities during the second quarter of 2020 for the XmAb24306 program. There is $4.6 million in deferred revenue as of June 30, 2020 which reflects the Company’s obligation to perform research services during the remaining research term. Astellas Effective March 29, 2019, the Company entered into a Research and License Agreement (Astellas Agreement) with Astellas Pharma Inc. (Astellas) pursuant to which the Company and Astellas will conduct a discovery program to characterize compounds and products for development and commercialization. Under the Astellas Agreement, Astellas was granted a worldwide exclusive license, with the right to sublicense products in the field created by the research activities. Pursuant to the Astellas Agreement, the Company will apply its bispecific Fc technology to research antibodies provided by Astellas to generate bispecific antibody candidates and will conduct limited testing and characterization of the bispecific candidates and return the candidates to Astellas for development and commercialization. The activities will be conducted under a research plan agreed to by both parties to the Astellas Agreement. Astellas will assume full responsibility for development and commercialization of the antibody candidate. Pursuant to the Astellas Agreement, the Company received an upfront payment of $15.0 million and is eligible to receive up to $240.0 million in milestones which include $32.5 million in development milestones, $57.5 million in regulatory milestones and $150.0 million in sales milestones. If commercialized, the Company is eligible to receive royalties on net sales that range from the high-single to low-double digit percentages. The Company recognized the $13.6 million allocated to the bispecific antibodies when it satisfied its performance obligation and transferred the bispecific antibodies to Astellas in June 2019. The $1.4 million allocated to the research activities is being recognized as the research services are being completed over the period of time the Company expects to complete the activities under the research plan. The Company completed the remaining activities under the research plan during the second quarter of 2020. For the three months ended June 30, 2020 and 2019, the Company recognized $0.7 million and $13.8 million of revenue related to the arrangement, respectively. For the six months ended June 30, 2020 and 2019, the Company recognized $0.9 million and $13.8 million of revenue, respectively. There is no deferred revenue as of June 30, 2020 related to the arrangement. Novartis In June 2016, the Company entered into a Collaboration and License Agreement (Novartis Agreement) with Novartis Institutes for BioMedical Research, Inc. (Novartis), to develop and commercialize bispecific and other Fc engineered antibody drug candidates using the Company’s proprietary XmAb technologies and drug candidates. The Company received an upfront payment of $150.0 million and is eligible to receive additional development, regulatory and sales milestones. Pursuant to the Novartis Agreement: ● The Company granted Novartis certain exclusive rights to research, develop and commercialize vibecotamab (XmAb14045) and plamotamab (XmAb13676), two development stage products that incorporate the Company’s bispecific Fc technology; ● The Company will apply its bispecific technology in up to four target pair antibodies identified by Novartis (each a Global Discovery Program); and ● The Company will provide Novartis with a non-exclusive license to certain of its Fc technologies to apply against up to ten targets identified by Novartis. Under the Novartis Agreement, the Company and Novartis are co-developing vibecotamab worldwide and sharing development costs. In December 2018, Novartis notified the Company it was terminating its rights with respect to the plamotamab program, which became effective June 2019. The Company has completed delivery of two target pair antibodies under the Agreement and in December 2019 Novartis initiated a Phase 1 study with one of the target pair antibodies. No revenue was recognized during the three and six months ended June 30, 2020 and 2019. As of June 30, 2020, there is a receivable of $1.0 million related to cost-sharing of development activities for the second quarter of 2020 for the vibecotamab program, and $40.1 million in deferred revenue related to the obligation to deliver two additional Global Discovery Programs to Novartis under the arrangement. Amgen Inc. In September 2015, the Company entered into a research and license agreement (the Amgen Agreement) with Amgen Inc. (Amgen) to develop and commercialize bispecific antibody product candidates using the Company’s proprietary XmAb bispecific Fc technology. Under the Amgen Agreement, the Company granted an exclusive license to Amgen to the rights to our CD38 x CD3 preclinical program and developed AMG 424. Amgen also applied our bispecific Fc technology to create AMG 509, a STEAP1 x CD3 XmAb 2+1 bispecific antibody. The Company has received a total of $60.5 million in upfront payments and milestone payments and is eligible to receive up to $255.0 million in future development, regulatory and sales milestone payments in total for the STEAP1 x CD3 program and is eligible to receive royalties on any global net sales of products. In May 2020, Amgen notified the Company that it was terminating its rights with respect to the CD38 x CD3 program, including AMG 424, which termination became effective July 2020. Under the terms of the Agreement, the rights to the AMG 424 program revert to the Company in connection with the termination. No revenue was recognized under the arrangement during the three and six months ended June 30, 2020 or 2019. As of June 30, 2020, there is no deferred revenue related to the arrangement. MorphoSys AG In June 2010, the Company entered into a Collaboration and License Agreement with MorphoSys AG (MorphoSys), which was subsequently amended. Under the agreement, we granted MorphoSys an exclusive worldwide license to the Company’s patents and know-how to research, develop and commercialize the XmAb5574 product candidate (subsequently renamed MOR208 and tafasitamab) with the right to sublicense under certain conditions. If certain developmental, regulatory and sales milestones are achieved, the Company is eligible to receive future milestone payments and royalties. In February 2020, the U.S. Food and Drug Administration (FDA) accepted MorphoSys’ Biologics License Application (BLA) for tafasitamab and the Company received a milestone payment of $12.5 million. The Company recognized the payment as revenue in the period that the milestone event occurred. On July 31, 2020, the FDA approved MorphoSys’ BLA for tafasitamab (now Monjuvi®). In connection with the approval, the Company will receive a milestone payment of $25.0 million. The Company will recognize the payment as revenue in the period that the milestone event occurs. No revenue was recognized under this arrangement for the three months ended June 30, 2020. The Company recognized $12.5 million of milestone revenue for the six months ended June 30, 2020. No revenue was recognized under this arrangement for the three and six months ended June 30, 2019. As of June 30, 2020, there is no deferred revenue related to this agreement. Alexion Pharmaceuticals, Inc. In January 2013, the Company entered into an option and license agreement with Alexion Pharmaceuticals, Inc. (Alexion). Under the terms of the agreement, the Company granted to Alexion an exclusive research license, with limited sublicensing rights, to make and use the Company’s Xtend technology to evaluate and advance compounds. Alexion exercised its rights to one target program, ALXN1210, which is now marketed as Ultomiris®. The Company is eligible to receive contractual milestones for certain commercial achievements and is also entitled to receive royalties based on a percentage of net sales of Ultomiris sold by Alexion, its affiliates or its sublicensees, which percentage is in the low single digits. Alexion’s royalty obligations continue on a product-by-product and country-by-country basis until the expiration of the last-to-expire valid claim in a licensed patent covering the applicable product in such country. Under ASC 606, the Company recognizes revenue for sales-based royalties upon the subsequent sale of the product. We began earning royalty revenue from the sale of Ultomiris in 2019. The Company recognized $3.8 million and $1.1 million of royalty revenue under this arrangement for the three months ended June 30, 2020 and 2019, respectively. The Company also recognized $4.0 million of milestone revenue for the three months ended June 30, 2019. The Company recognized total revenue of $7.2 million and $5.1 million for the six months ended June 30, 2020 and 2019, respectively. As of June 30, 2020, there is a receivable of $7.4 million related to royalties due under the arrangement. There is no deferred revenue related to this agreement. INmune Bio, Inc. In October 2017, the Company entered into a License Agreement (Agreement) with INmune Bio, Inc. (INmune). Under the terms of the agreement, the Company provided INmune with an exclusive license to certain rights to a proprietary protein, XPRO1595. Under the agreement the Company received an upfront payment of $100,000, 1,585,000 shares of INmune common stock and an option to acquire additional shares of INmune. The Company is also eligible to receive a percentage of sublicensing revenue received for XPRO1595 and royalties in the mid-single digit percent range on the sale of approved products. The option has a six-year term from the date of the Agreement and provides the Company the option to purchase up to 10% of the fully diluted outstanding shares of INmune for $10.0 million. The Company has recorded its equity interest in INmune at cost pursuant to ASC 323. The Company did not record its share of the net loss from INmune during the three and six months ended June 30, 2020 or 2019, respectively, as the carrying value of this investment has been reduced to zero . The Company did not recognize any revenue related to the agreement for the three and six months ended June 30, 2020 and 2019. There is no deferred revenue as of June 30, 2020 related to this agreement. Vir Biotechnology, Inc. In the third quarter of 2019, the Company entered into a Patent License Agreement (the VirBio Agreement) with Vir Biotechnology (VirBio) pursuant to which the Company provided a non-exclusive license to its Xtend technology for up to two targets. Under the terms of the VirBio Agreement, the Company received an upfront payment and is eligible to receive total milestones of $155.25 million which include $5.25 million of development milestones, $30.0 million of regulatory milestones and $120.0 million of sales milestones. In addition, the Company is eligible to receive royalties on the net sales of approved products in the low single digit percent range. The Company evaluated the VirBio Agreement and determined that the single performance obligation was access to a non-exclusive license to certain patents of the Company which were transferred to VirBio upon execution of the VirBio Agreement in July 2019. VirBio initiated a Phase 1 study with a licensed antibody in 2019 and in the second quarter of 2020 it initiated a Phase 1 study with a second licensed antibody. In March 2020, the Company entered into a second Patent License Agreement (the Second VirBio Agreement) with VirBio pursuant to which the Company provided a non-exclusive license to its Xtend technology to extend the half-life of novel antibodies VirBio is investigating as potential treatments for patients with SARS-CoV-2, which causes COVID-19. Under the terms of the Second VirBio Agreement, VirBio is responsible for all research, development, regulatory and commercial activities for the antibody, and the Company is eligible to receive royalties on the net sales of approved products in the mid-single digit percent range. The Company determined that the Second VirBio Agreement was a modification of the original agreement and the transfer of the license occurred at inception of the VirBio Agreement. The total consideration under the arrangement did not change with the Second VirBio Agreement as the Company will potentially receive additional royalty revenue which is variable consideration and is not included in the transaction price. The Company recognized $0.3 million milestone revenue for the three and six months ended June 30, 2020. The Company did not recognize revenue related to the agreement for the three and six months ended June 30, 2019. There is no deferred revenue as of June 30, 2020 related to this agreement. Aimmune Therapeutics, Inc. On February 4, 2020, the Company entered into a License, Development and Commercialization Agreement (the Aimmune Agreement) with Aimmune Therapeutics, Inc. (Aimmune) pursuant to which the Company granted Aimmune an exclusive worldwide license to XmAb7195, which was renamed AIMab7195. Under the Aimmune Agreement, Aimmune will be responsible for all further development and commercialization activities for XmAb7195. The Company received an upfront payment of $5.0 million and 156,238 shares of Aimmune common stock with an aggregate value of $4.6 million on the closing date. Under the Aimmune Agreement, the Company is also eligible to receive up to $385.0 million in milestones, which include $22.0 million in development milestones, $53.0 million in regulatory milestones and $310.0 million in sales milestones, and tiered royalties on net sales of approved products from high-single to mid-teen percent range. Under the Aimmune Agreement, Aimmune received exclusive worldwide rights to manufacture, develop and commercialize XmAb7195. They also received the rights to all data, information and research materials related to the XmAb7195 program. The Company evaluated the Aimmune Agreement under the revenue recognition standard ASC 606 and identified the following performance obligations that it deemed to be distinct at the inception of the contract: ● License to the rights to the XmAb7195 drug candidate; and ● Rights to material, data and information that the Company had accumulated in connection with manufacturing, testing and conducting clinical trials for the XmAb7195 program and intellectual property filings and information (XmAb7195 data). The Company considered the licenses as functional intellectual property as Aimmune has the right to use XmAb7195 at the time that the Company transfers such rights. The rights to the XmAb7195 data are not considered to be separate from the license to XmAb7195 as Aimmune cannot benefit from the license without the supporting data and documentation. The Company determined the transaction price at inception is $9.6 million which consists of the $5.0 million upfront payment and the 156,238 shares of Aimmune common stock which had a value of $4.6 million on the closing date. The Company determined that the transaction price is to be allocated to the performance obligations. The Aimmune Agreement includes variable consideration for potential future milestones and royalties that were contingent on future success factors for the XmAb7195 program. The Company used the “most likely amount” method to determine the variable consideration. None of the development, regulatory or sales milestones or royalties were included in the transaction price. The Company will re-evaluate the transaction price in each reporting period as uncertain events are resolved or other changes in circumstances occur. The Company determined the transaction price at inception of the Aimmune Agreement and allocated it to the performance obligation, delivery of the XmAb7195 license. The Company completed delivery of its performance obligations in March 2020. The license to XmAb7195 was transferred to Aimmune at inception of the Aimmune Agreement, and the XmAb7195 data was transferred to Aimmune in March 2020. No revenue was recognized in the three months ended June 30, 2020. The Company recognized $9.6 million of revenue related to the agreement for the six months ended June 30, 2020. There is no deferred revenue as of June 30, 2020 related to this agreement. Gilead Sciences, Inc. In January 2020, the Company entered into a Technology License Agreement (the Gilead Agreement) with Gilead Sciences, Inc. (Gilead), in which the Company provided an exclusive license to its Cytotoxic Fc and Xtend Fc technologies for an initial identified antibody and options for up to three additional antibodies directed to the same molecular target. The Company retains the right to grant licenses for other antibodies directed to the target, subject to the Company’s approval. Gilead is responsible for all development and commercialization activities for all target candidates. The Company received an upfront payment of $6.0 million and is eligible to receive up to $67.0 million in milestones, which include $10.0 million in development milestones, $27.0 million in regulatory milestones and $30.0 million in sales milestones for each product incorporating the antibodies selected. In addition, the Company is eligible to receive royalties in the low-single digit percentage range on net sales of approved products. In March 2020, Gilead exercised options on two additional antibody compounds and in April 2020 it exercised the option on the third antibody available under the Gilead Agreement. In April 2020, we received a total of $7.5 million in payment of the three options. The Company evaluated the Gilead Agreement under the revenue recognition standard ASC 606 and identified the following performance obligations that it deemed to be distinct at the inception of the contract: ● Non-exclusive license to its Cytotoxic Fc and Xtend Fc technologies; and, ● Options for four exclusive commercial licenses to incorporate the licensed technologies on approved target compounds The Company considered the licenses as functional intellectual property as Gilead has the right to use the technologies at the time that the Company transfers such rights. Each of the four options is considered a separate performance obligation as the arrangement does not confer material rights to the options without payment of the option exercise fee. Gilead will benefit from each option upon exercise of each of the four options and payment of each option fee as Gilead has access to each technology at inception of the arrangement and the rights are transferred upon payment of each option fee. The total transaction price is $13.5 million which includes the upfront payment of $6.0 million and the option fee payment of $7.5 million which was contractually due with the exercise of the three options by Gilead. The milestone payments are variable consideration to which the Company applied the “most likely amount” method and concluded at inception of the Gilead Agreement it is unlikely that the Company will collect such payments. The milestone payments were not included in the transaction price and the Company will review this conclusion and update at each reporting period. The Company allocated $3.5 million of the transaction price to the licenses to the cytotoxic Fc and Xtend Fc technologies and recognized income for the licenses at inception of the arrangement when Gilead began benefiting access to them. The Company allocated The Company recognized ​ Revenue earned The revenues recorded for the three and six months ended June 30, 2020 were earned principally from the following licensees (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended Six Months Ended ​ ​ June 30, June 30, ​ ​ 2020 ​ 2019 2020 ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ Aimmune ​ $ — $ — ​ $ 9.6 ​ $ — Alexion ​ 3.8 ​ ​ 5.1 ​ ​ 7.2 ​ 5.1 Astellas ​ ​ 0.7 ​ ​ 13.8 ​ ​ 0.9 ​ ​ 13.8 Genentech ​ ​ 0.8 ​ ​ 0.6 ​ ​ 1.5 ​ ​ 112.5 Gilead ​ ​ 7.5 ​ ​ — ​ ​ 13.5 ​ ​ — MorphoSys ​ ​ — ​ ​ — ​ ​ 12.5 ​ ​ — Vir Biotechnology ​ ​ 0.3 ​ — ​ ​ 0.3 ​ — Total ​ $ 13.1 ​ $ 19.5 ​ $ 45.5 ​ $ 131.4 ​ The table below summarizes the disaggregation of revenue recorded for the three and six months ended June 30, 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended Six Months Ended ​ ​ June 30, June 30, ​ ​ 2020 ​ 2019 2020 ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ Research collaboration $ 1.5 $ 14.4 ​ $ 2.4 $ 14.7 Milestone ​ ​ 0.3 ​ 4.0 ​ ​ 12.8 ​ 4.0 Licensing ​ ​ 7.5 ​ — ​ ​ 23.1 ​ 111.6 Royalties ​ ​ 3.8 ​ ​ 1.1 ​ ​ 7.2 ​ ​ 1.1 Total ​ $ 13.1 ​ $ 19.5 ​ $ 45.5 ​ $ 131.4 ​ Remaining Performance Obligations and Deferred Revenue The Company’s remaining performance obligations are delivery of two Global Discovery Programs under the Novartis Agreement and conducting research activities pursuant to research plans under the Genentech Agreement. We have completed the remaining research activities pursuant to the research plan under the Astellas Agreement in the three-month period ended June 30, 2020. As of June 30, 2020 and 2019, the Company has deferred revenue of $44.7 million and $48.8 million, respectively. As of June 30, 2020, all deferred revenue is classified as current liabilities as the Company’s obligations to perform services are due on demand when requested by Novartis under the Novartis Agreement and the Company’s obligation to perform research services to Genentech will end upon expiration of the research term within one year . As of June 30, 2019, $45.5 million was classified as current liabilities for the same reason, and $3.3 million of the deferred revenue liability was classified as long-term for the portion of obligations to perform research services to Genentech after one year .

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2020
Income Taxes
Income Taxes	10. Income taxes ​ On March 27, 2020, the president signed the Coronavirus Aid, Relief and Economic Security (CARES) Act. The legislation provides several changes to corporation income taxes including: ​ ● Modification of the rules applicable to the deductibility of net operation losses (NOLs) incurred in tax years beginning in 2018, 2019 and 2020, and ● Acceleration of the corporate minimum tax credit. ​ The Company reviewed the new legislation and determined that certain provisions would provide income tax benefits: ​ ● The Company has NOL and income tax credit carryforwards which are subject to a valuation allowance, due to uncertainty about the ability to utilize such losses and credits in future periods. Accordingly, the Company does not expect the changes in the NOL provisions in the legislation to provide any benefit in the near-term. ● As of December 31, 2019, the Company had recorded a receivable of $0.8 million related to the corporate minimum tax credit. Under previous income tax provisions, one-half of the minimum tax credit would be received in 2020 and the remainder in subsequent years. As a result of the new legislation, the Company will receive a refund for the entire $0.8 million minimum tax credit in 2020. ​ There was no provision for income taxes for the three and six months ended June 30, 2020. The provision for income taxes of $0.9 million for the six months ended June 30, 2019 represents the interim period tax allocation of the state alternative minimum tax based on the Company’s projected year-end effective income tax rates which cannot be offset by the Company’s net operating loss carryforwards. The Company has a federal income tax receivable of $0.8 million at June 30, 2020 related to refundable alternative minimum tax credits. As of June 30, 2020, the Company’s deferred income tax assets, consisting primarily of net operating loss and tax credit carryforwards, have been fully offset by a valuation allowance. ​

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Polices)	6 Months Ended
	Jun. 30, 2020
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation ​ The accompanying unaudited interim financial statements for Xencor, Inc. (the Company, Xencor, we or us) have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information. The financial statements include all adjustments (consisting only of normal recurring adjustments) that the management of the Company believes are necessary for a fair presentation of the periods presented. The preparation of interim financial statements requires the use of management’s estimates and assumptions that affect reported amounts of assets and liabilities at the date of the interim financial statements and the reported revenues and expenditures during the reported periods. These interim financial results are not necessarily indicative of the results expected for the full fiscal year or for any subsequent interim period. ​ The accompanying unaudited interim financial statements and related notes should be read in conjunction with the audited financial statements and notes thereto included in the Company’s 2019 Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on February 25, 2020.
Use of Estimates	Use of Estimates ​ The preparation of interim financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, other comprehensive gain (loss) and the related disclosures. On an ongoing basis, management evaluates its estimates, including estimates related to its accrued clinical trial and manufacturing development expenses, stock-based compensation expense, intangible assets and related amortization. Significant estimates in these interim financial statements include estimates made for royalties and accrued research and development expenses, stock-based compensation expenses, intangible assets and related amortization, estimated standalone selling price of performance obligations, the likelihood of recognizing variable consideration, and recoverability of deferred tax assets.
Intangible Assets	Intangible Assets ​ The Company maintains definite-lived intangible assets related to certain capitalized costs of acquired licenses and third-party costs incurred in establishing and maintaining its intellectual property rights to its platform technologies and development candidates. These assets are amortized over their useful lives, which are estimated to be the remaining patent life or the contractual term of the license. The straight-line method is used to record amortization expense. The Company assesses its intangible assets for impairment if indicators are present or changes in circumstances suggest that impairment may exist. There were no impairment charges recorded for the three and six months ended June 30, 2020 and 2019. ​ The Company capitalizes certain in-process intangible assets that are then abandoned when they are no longer pursued or used in current research activities. There was no material abandonment of in-process intangible assets during the three and six months ended June 30, 2020 and 2019.
Marketable and Equity Securities	Marketable and Equity Securities ​ The Company has an investment policy that includes guidelines on acceptable investment securities, minimum credit quality, maturity parameters, and concentration and diversification. The Company invests its excess cash primarily in marketable debt securities issued by investment grade institutions. ​ The Company considers its marketable debt securities to be available-for-sale and does not intend to sell these securities, and it is not more likely than not that the Company will be required to sell the securities before recovery of the amortized cost basis. These assets are carried at fair value and any impairment losses and recoveries related to the underlying issuer’s credit standing are recognized within other income (expense), while non-credit related impairment losses and recoveries are recognized within accumulated other comprehensive income (loss). There were no impairment losses or recoveries recorded for the three and six months ended June 30, 2020 and 2019. Accrued interest on marketable debt securities is included in marketable securities’ carrying value. Each reporting period, the Company reviews its portfolio of marketable debt securities, using both quantitative and qualitative factors, to determine if each security’s fair value has declined below its amortized cost basis. ​ The Company also has an investment in an equity security that is carried at fair value with changes in fair value recognized within other income (expense). For equity securities with a readily determinable fair value, the Company remeasures these equity investments at each reporting period until such time that the investment is sold or disposed. If the Company sells an investment, any realized gains and losses on the sale of the securities will be recognized within other income (expense) in the Statement of Comprehensive Income (Loss) in the period of sale.
Recent Accounting Pronouncements	Recent Accounting Pronouncements ​ Pronouncements Adopted in 2020 ​ Effective January 1, 2020, the Company adopted ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, as well as ASU No, 2018-19, Codification Improvements to Topic 326, Financial Instruments – Credit Losses. The standard amends guidance on reporting credit losses for assets held at amortized cost basis and also provides an available-for-sale (AFS) debt security impairment model that is a modified version of the other-than-temporary-impairment (OTTI) model. The AFS debt security impairment model no longer allows consideration of the length of time during which the fair value has been less than its amortized cost when determining whether a credit loss exists. The adoption of this standard did not have any impact on the Company’s financial statements. ​ Effective January 1, 2020, the Company adopted ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement, which modifies the disclosures for transfers between Level 1 and Level 2 of the fair value hierarchy, modifies the Level 3 disclosure requirements for non-public entities and requires additional disclosure for Level 3 fair value hierarchy. The adoption of this standard did not have any impact on the Company’s financial statements. ​ Effective January 1, 2020, the Company adopted ASU No. 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606, which provides guidance on how to assess whether certain transactions between collaborative arrangement participants should be accounted for within the revenue recognition standard. The adoption of this standard did not have any impact on the Company’s financial statements. ​ Pronouncements Not Yet Effective ​ In December 2019, the Financial Accounting Standards Board (FASB) issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ​ In January 2020, the FASB issued ASU No. 2020-01, which clarifies that a company should consider observable transactions that require a company to either apply or discontinue the equity method of accounting under Topic 323, Investment – Equity Method and Joint Ventures, for the purposes of applying the measurement alternative in accordance with Topic 321 immediately before applying or upon discontinuing the equity method. The amendment is effective for fiscal years beginning after December 15, 2020. The Company does not anticipate that the standard will have a significant impact on its financial statements. ​ There have been no other material changes to the significant accounting policies previously disclosed in the Company’s 2019 Annual Report on Form 10-K.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2020
Fair Value of Financial Instruments
Schedule of assets recorded at fair value	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2020 ​ December 31, 2019 ​ Total ​ ​ ​ ​ Total ​ ​ ​ ​ ​ ​ Fair Value ​ Level 1 ​ Level 2 ​ Fair Value ​ Level 1 ​ Level 2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money Market Funds ​ $ 103,231 ​ $ 103,231 ​ $ — ​ $ 32,009 ​ $ 32,009 ​ $ — Corporate Securities ​ ​ 267,542 ​ ​ — ​ ​ 267,542 ​ ​ 281,751 ​ ​ — ​ ​ 281,751 Government Securities ​ ​ 207,717 ​ ​ — ​ ​ 207,717 ​ ​ 269,245 ​ ​ — ​ ​ 269,245 Equity Securities with Readily Determinable Fair Value ​ ​ 2,611 ​ ​ 2,611 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ $ 581,101 ​ $ 105,842 ​ $ 475,259 ​ $ 583,005 ​ $ 32,009 ​ $ 550,996

Net Income (Loss) Per Share (Ta

Net Income (Loss) Per Share (Tables)	6 Months Ended
	Jun. 30, 2020
Net Income (Loss) Per Share
Schedule of basic and diluted net income (loss) per common share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended Six Months Ended ​ ​ June 30, ​ June 30, ​ 2020 2019 2020 2019 ​ ​ (in thousands, except share and per share data) Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) attributable to common stockholders ​ $ (35,018) ​ $ (16,034) ​ $ (43,092) ​ $ 64,012 Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average common shares outstanding used in computing basic net income (loss) ​ 57,059,610 ​ 56,399,255 ​ ​ 57,003,162 ​ ​ 56,351,377 Effect of dilutive securities ​ ​ — ​ ​ — ​ ​ — ​ ​ 1,691,442 Weighted-average common shares outstanding used in computing diluted net income (loss) ​ ​ 57,059,610 ​ ​ 56,399,255 ​ ​ 57,003,162 ​ ​ 58,042,819 Basic net income (loss) per common share ​ $ (0.61) ​ $ (0.28) ​ $ (0.76) ​ $ 1.14 Diluted net income (loss) per common share ​ $ (0.61) ​ $ (0.28) ​ $ (0.76) ​ $ 1.10

Marketable and Equity Securit_2

Marketable and Equity Securities (Tables)	6 Months Ended
	Jun. 30, 2020
Marketable and Equity Securities
Schedule of marketable securities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ Amortized Unrealized ​ Unrealized ​ June 30, 2020 ​ Cost ​ Gains ​ Losses ​ Fair Value (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money Market Funds ​ $ 103,231 ​ $ — ​ $ — ​ $ 103,231 Corporate Securities ​ ​ 266,756 ​ ​ 786 ​ ​ — ​ ​ 267,542 Government Securities ​ ​ 207,010 ​ ​ 710 ​ ​ (3) ​ ​ 207,717 ​ ​ $ 576,997 ​ $ 1,496 ​ $ (3) ​ $ 578,490 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported as ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 103,231 Marketable securities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 475,259 Total investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 578,490 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ Amortized Unrealized ​ Unrealized ​ December 31, 2019 ​ Cost ​ Gains ​ Losses ​ Fair Value (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money Market Funds ​ $ 32,009 ​ $ — ​ $ — ​ $ 32,009 Corporate Securities ​ ​ 281,586 ​ ​ 195 ​ ​ (30) ​ ​ 281,751 Government Securities ​ ​ 268,239 ​ ​ 1,006 ​ ​ — ​ ​ 269,245 ​ ​ $ 581,834 ​ $ 1,201 ​ $ (30) ​ $ 583,005 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reported as ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 32,009 Marketable securities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 550,996 Total investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 583,005
Schedule of maturities of marketable securities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized Estimated June 30, 2020 ​ Cost ​ Fair Value (in thousands) ​ ​ ​ ​ ​ ​ Mature in one year or less ​ $ 472,639 ​ $ 474,114 Mature within two years ​ ​ 1,127 ​ ​ 1,145 ​ ​ $ 473,766 ​ $ 475,259
Schedule of unrealized losses on available-for-sale investments	​ The unrealized losses on available-for-sale investments and their related fair values as of June 30, 2020 and December 31, 2019 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less than 12 months ​ 12 months or greater ​ ​ ​ ​ ​ Unrealized ​ ​ ​ ​ Unrealized June 30, 2020 ​ Fair value ​ losses ​ Fair value ​ losses (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Government Securities ​ ​ 49,973 ​ ​ (3) ​ ​ — ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less than 12 months ​ 12 months or greater ​ ​ ​ ​ ​ Unrealized ​ ​ ​ ​ Unrealized December 31, 2019 ​ Fair value ​ losses ​ Fair value ​ losses (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate Securities ​ $ 46,303 ​ $ (24) ​ $ 13,992 ​ $ (6)

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2020
Stock-Based Compensation
Schedule of total employee, director and non-employee stock-based compensation expense recognized	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended Six Months Ended ​ ​ June 30, June 30, ​ 2020 2019 2020 2019 General and administrative ​ $ 2,804 ​ $ 2,008 ​ $ 5,095 ​ $ 3,862 Research and development ​ 5,427 ​ 7,295 ​ 9,648 ​ 11,297 ​ ​ $ 8,231 ​ $ 9,303 ​ $ 14,743 ​ $ 15,159 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ ​ 2020 2019 ​ 2020 2019 Stock options ​ $ 6,667 ​ $ 8,946 ​ $ 12,549 ​ $ 14,470 ESPP ​ ​ 213 ​ ​ 195 ​ ​ 407 ​ ​ 413 Restricted stock units ​ ​ 1,351 ​ ​ 162 ​ ​ 1,787 ​ ​ 276 ​ ​ $ 8,231 ​ $ 9,303 ​ $ 14,743 ​ $ 15,159
Summary of stock option activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Weighted ​ ​ ​ ​ ​ ​ Average Average ​ ​ ​ ​ Number of ​ Exercise Remaining ​ Aggregate ​ ​ Shares Subject ​ Price Contractual ​ Intrinsic ​ ​ to Outstanding ​ (Per Term ​ Value ​ ​ Options ​ Share) (in years) ​ (in thousands) Balances at December 31, 2019 7,174,319 ​ $ 24.03 ​ ​ 7.32 ​ ​ ​ Options granted 1,433,699 ​ $ 32.10 ​ ​ ​ ​ ​ ​ Options forfeited (115,261) ​ $ 31.28 ​ ​ ​ ​ ​ ​ Options exercised (261,786) ​ $ 18.13 ​ ​ ​ ​ ​ ​ Balances at June 30, 2020 8,230,971 ​ $ 25.52 ​ ​ 7.33 ​ $ 65,362 Exercisable ​ 4,587,110 ​ $ 20.28 ​ ​ 6.10 ​ $ 58,544
Schedule of weighted average assumptions used for estimation of fair value of stock options	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options ​ Options ​ ​ Three Months Ended ​ Six Months Ended ​ ​ ​ June 30, ​ June 30, ​ 2020 2019 2020 2019 Expected term (years) ​ 5.7 5.9 ​ 6.2 6.0 ​ Expected volatility ​ 56.1 % 61.3 % 54.3 % 61.3 % Risk-free interest rate ​ 0.41 % 2.07 % 0.84 % 2.43 % Expected dividend yield ​ — % — % — % — %
Schedule of weighted average assumptions used for estimation of fair value of ESPP	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ESPP ​ ESPP ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ 2020 2019 2020 2019 Expected term (years) 0.5 - 2.0 0.5 - 2.0 ​ 0.5 - 2.0 0.5 - 2.0 ​ Expected volatility ​ 50.8 - 62.6 % 55.0 - 71.4 % 50.8 - 62.6 % 55.0 - 71.4 % Risk-free interest rate 0.18 - 1.65 % 1.47 - 2.70 % 0.18 - 1.65 % 1.47 - 2.70 % Expected dividend yield ​ — % — % — % — %
Summary of restricted stock unity activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ Restricted ​ Average Grant ​ ​ Stock ​ Date Fair Value ​ ​ Units ​ (Per unit) ​ ​ ​ ​ ​ ​ Unvested at December 31, 2019 90,006 ​ $ 34.66 Granted 305,794 ​ ​ 31.64 Vested (21,822) ​ ​ 31.91 Forfeited (7,311) ​ ​ 31.47 Unvested at June 30, 2020 366,667 ​ $ 32.37

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2020
Leases
Schedule of operating lease liabilities maturities	The following table reconciles the undiscounted cash flows for the operating leases at June 30, 2020 to the operating lease liabilities recorded on the balance sheet (in thousands): ​ ​ ​ ​ ​ Years ending December 31, ​ ​ For the remainder of 2020 ​ $ 1,297 2021 ​ 2,583 2022 ​ ​ 2,203 2023 ​ ​ 1,347 2024 ​ ​ 1,366 2025 ​ ​ 1,212 Thereafter ​ ​ 1,238 Total undiscounted lease payments ​ ​ 11,246 Less: Imputed interest ​ ​ (1,526) Present value of lease payments ​ $ 9,720 ​ ​ ​ ​ Lease liabilities - short-term ​ $ 2,094 Lease liabilities - long-term ​ ​ 7,626 Total lease liabilities ​ $ 9,720
Summary of lease costs and cash disclosures	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ ​ 2020 2019 ​ 2020 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease cost ​ $ 648 ​ $ 650 ​ $ 1,297 ​ $ 1,299 Variable lease cost ​ ​ 38 ​ ​ 47 ​ ​ 59 ​ ​ 57 Total lease costs ​ $ 686 ​ $ 697 ​ $ 1,356 ​ $ 1,356 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash paid for amounts included in ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ the measurement of lease liabilities ​ $ 566 ​ $ 344 ​ $ 1,123 ​ $ 854

Collaboration and Licensing A_2

Collaboration and Licensing Agreements (Tables)	6 Months Ended
	Jun. 30, 2020
Collaboration and Licensing Agreements
Schedule of revenue by licensees	The revenues recorded for the three and six months ended June 30, 2020 were earned principally from the following licensees (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended Six Months Ended ​ ​ June 30, June 30, ​ ​ 2020 ​ 2019 2020 ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ Aimmune ​ $ — $ — ​ $ 9.6 ​ $ — Alexion ​ 3.8 ​ ​ 5.1 ​ ​ 7.2 ​ 5.1 Astellas ​ ​ 0.7 ​ ​ 13.8 ​ ​ 0.9 ​ ​ 13.8 Genentech ​ ​ 0.8 ​ ​ 0.6 ​ ​ 1.5 ​ ​ 112.5 Gilead ​ ​ 7.5 ​ ​ — ​ ​ 13.5 ​ ​ — MorphoSys ​ ​ — ​ ​ — ​ ​ 12.5 ​ ​ — Vir Biotechnology ​ ​ 0.3 ​ — ​ ​ 0.3 ​ — Total ​ $ 13.1 ​ $ 19.5 ​ $ 45.5 ​ $ 131.4
Schedule of disaggregation of revenue	The table below summarizes the disaggregation of revenue recorded for the three and six months ended June 30, 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended Six Months Ended ​ ​ June 30, June 30, ​ ​ 2020 ​ 2019 2020 ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ Research collaboration $ 1.5 $ 14.4 ​ $ 2.4 $ 14.7 Milestone ​ ​ 0.3 ​ 4.0 ​ ​ 12.8 ​ 4.0 Licensing ​ ​ 7.5 ​ — ​ ​ 23.1 ​ 111.6 Royalties ​ ​ 3.8 ​ ​ 1.1 ​ ​ 7.2 ​ ​ 1.1 Total ​ $ 13.1 ​ $ 19.5 ​ $ 45.5 ​ $ 131.4

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Summary of Significant Accounting Policies
Impairment of intangible assets	$ 0	$ 0	$ 0	$ 0
Impairment loss or recoveries	$ 0	$ 0	$ 0	$ 0

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Fair Value of Financial Instruments
Money Market Funds	$ 109,534	$ 50,312
Marketable Securities	475,259
Equity Securities with Readily Determinable Fair Value	2,611
Total Fair Value	581,101	583,005
Transfers from level 1 to level 2	0		$ 0
Transfers from level 2 to level 1	0		$ 0
Money Market Funds
Fair Value of Financial Instruments
Money Market Funds	103,231	32,009
Corporate Securities
Fair Value of Financial Instruments
Marketable Securities	267,542	281,751
Government Securities
Fair Value of Financial Instruments
Marketable Securities	207,717	269,245
Level 1
Fair Value of Financial Instruments
Equity Securities with Readily Determinable Fair Value	2,611
Total Fair Value	105,842	32,009
Level 1 | Money Market Funds
Fair Value of Financial Instruments
Money Market Funds	103,231	32,009
Level 2
Fair Value of Financial Instruments
Total Fair Value	475,259	550,996
Level 2 | Corporate Securities
Fair Value of Financial Instruments
Marketable Securities	267,542	281,751
Level 2 | Government Securities
Fair Value of Financial Instruments
Marketable Securities	$ 207,717	$ 269,245

Net Income (Loss) Per Share (De

Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator:
Net income (loss) attributable to common stockholders	$ (35,018)	$ (16,034)	$ (43,092)	$ 64,012
Denominator:
Weighted average common shares outstanding, basic	57,059,610	56,399,255	57,003,162	56,351,377
Effect of dilutive securities				1,691,442
Weighted average common shares outstanding, diluted	57,059,610	56,399,255	57,003,162	58,042,819
Basic net income (loss) (in dollars per share)	$ (0.61)	$ (0.28)	$ (0.76)	$ 1.14
Diluted net income (loss) (in dollars per share)	$ (0.61)	$ (0.28)	$ (0.76)	$ 1.10

Net Income (Loss) Per Share - A

Net Income (Loss) Per Share - Anti-dilutive securities (Details)	6 Months Ended
	Jun. 30, 2019shares
Net Income (Loss) Per Share
Securities excluded in calculation of EPS	1,173,829

Marketable Securities (Details)

Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities
Cash and cash equivalents	$ 109,534	$ 50,312
Investments, amortized cost	576,997	581,834
Investments	578,490	583,005
Total amortized cost	473,766
Gross unrealized gains	1,496	1,201
Gross unrealized losses	(3)	(30)
Marketable Securities	475,259
Marketable securities
Schedule of Available-for-sale Securities
Marketable Securities	475,259	550,996
Money Market Funds
Schedule of Available-for-sale Securities
Cash and cash equivalents	103,231	32,009
Corporate Securities
Schedule of Available-for-sale Securities
Total amortized cost	266,756	281,586
Gross unrealized gains	786	195
Gross unrealized losses		(30)
Marketable Securities	267,542	281,751
Government Securities
Schedule of Available-for-sale Securities
Total amortized cost	207,010	268,239
Gross unrealized gains	710	1,006
Gross unrealized losses	(3)
Marketable Securities	207,717	269,245
Cash and Cash Equivalents
Schedule of Available-for-sale Securities
Cash and cash equivalents	$ 103,231	$ 32,009

Marketable Securities - Maturit

Marketable Securities - Maturities (Details) $ in Thousands	Jun. 30, 2020USD ($)
Amortized Cost
Maturing in one year or less	$ 472,639
Maturing within two years	1,127
Total amortized cost	473,766
Estimate Fair Value
Maturing in one year or less	474,114
Maturing within two years	1,145
Total estimated fair value	$ 475,259

Marketable Securities - Unreali

Marketable Securities - Unrealized losses (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Unrealized losses
Equity securities, net unrealized losses	$ 300	$ (1,978)
Corporate Securities
Fair value
Fair value, less than 12 months			$ 46,303
Fair value, 12 months or greater			13,992
Unrealized losses
Unrealized losses, Less than 12 months			(24)
Unrealized losses, 12 months or greater			$ (6)
Government Securities
Fair value
Fair value, less than 12 months	49,973	49,973
Unrealized losses
Unrealized losses, Less than 12 months	$ (3)	$ (3)

Stock Based Compensation (Detai

Stock Based Compensation (Details)	Dec. 02, 2013shares	Jun. 30, 2020itemshares	Jun. 30, 2019shares
Employee stock options
Stock-based compensation
Options granted (in shares)		1,433,699	1,700,583
ESPP
Stock-based compensation
Total number of shares of common stock available for issuance		581,286
Awards issued under the plan (in shares)		445,621
Increase in shares of common stock available for issuance (in shares)		0
ESPP | Maximum
Stock-based compensation
Annual percentage increase in shares of common stock available for issuance		1.00%
Annual increase in shares of common stock available for issuance (in shares)		621,814
Restricted stock units
Stock-based compensation
Awards issued under the plan (in shares)		411,293
Granted		305,794
Annual installment vesting periods | item		3
The 2013 Plan
Stock-based compensation
Total number of shares of common stock available for issuance		12,116,313
Annual percentage increase in shares of common stock available for issuance		4.00%
Awards issued under the plan (in shares)		10,327,214
Increase in shares of common stock available for issuance (in shares)		1,138,046
The 2010 Plan
Stock-based compensation
Total number of shares of common stock available for issuance		2,684,456
Options granted (in shares)	0

Stock-Based Compensation - Empl

Stock-Based Compensation - Employee expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Stock-based compensation
Total employee, director and non-employee stock-based compensation expense	$ 8,231	$ 9,303	$ 14,743	$ 15,159
Employee stock options
Stock-based compensation
Total employee, director and non-employee stock-based compensation expense	6,667	8,946	12,549	14,470
ESPP
Stock-based compensation
Total employee, director and non-employee stock-based compensation expense	213	195	407	413
Restricted stock units
Stock-based compensation
Total employee, director and non-employee stock-based compensation expense	1,351	162	1,787	276
General and administrative
Stock-based compensation
Total employee, director and non-employee stock-based compensation expense	2,804	2,008	5,095	3,862
Research and development
Stock-based compensation
Total employee, director and non-employee stock-based compensation expense	$ 5,427	$ 7,295	$ 9,648	$ 11,297

Stock-Based Compensation - Opti

Stock-Based Compensation - Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 02, 2013	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Employee stock options
Number of Shares subject to outstanding options
Balance at the beginning of the period (in shares)		7,174,319
Options granted (in shares)		1,433,699	1,700,583
Options forfeited (in shares)		(115,261)
Options exercised (in shares)		(261,786)
Balance at the end of the period (in shares)		8,230,971		7,174,319
Exercisable options (in shares)		4,587,110
Weighted Average Exercise Price (Per Share)
Balance at the beginning of the period (in dollars per share)		$ 24.03
Options granted (in dollars per share)		32.10
Options forfeited (in dollars per share)		31.28
Options exercised (in dollars per share)		18.13
Balance at the end of the period (in dollars per share)		25.52		$ 24.03
Exercisable (in dollars per share)		$ 20.28
Weighted-average remaining contractual life		7 years 3 months 29 days		7 years 3 months 25 days
Weighted-average remaining contractual life of awards exercisable		6 years 1 month 6 days
Aggregate intrinsic value of options outstanding		$ 65,362
Aggregate intrinsic value of options exercisable		$ 58,544
Closing price of common stock (in dollars per share)		$ 32.39
Weighted average fair value of options granted (in dollars per share)		$ 16.44	$ 20.74
The 2010 Plan
Number of Shares subject to outstanding options
Options granted (in shares)	0

Stock-Based Compensation - FV o

Stock-Based Compensation - FV of employee stock options (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Employee stock options
Weighted average assumptions for estimated fair value of employee stock options
Expected volatility (as a percent)	56.10%	61.30%	54.30%	61.30%
Risk-free interest rate (as a percent)	0.41%	2.07%	0.84%	2.43%
Expected term (years)	5 years 8 months 12 days	5 years 10 months 24 days	6 years 2 months 12 days	6 years
Compensation expense
Unamortized compensation expense related to unvested options	$ 59.4		$ 59.4
Period to recognize unamortized compensation expense			2 years 9 months 18 days
ESPP
Weighted average assumptions for estimated fair value of employee stock options
Expected volatility, low end of range (as a percent)	50.80%	55.00%	50.80%	55.00%
Expected volatility, high end of range (as a percent)	62.60%	71.40%	62.60%	71.40%
Risk-free interest rate, low end of range (as a percent)	0.18%	1.47%	0.18%	1.47%
Risk-free interest rate, high end of range (as a percent)	1.65%	2.70%	1.65%	2.70%
Compensation expense
Unamortized compensation expense related to unvested options	$ 1.3		$ 1.3
Period to recognize unamortized compensation expense			1 year 4 months 24 days
ESPP | Minimum
Weighted average assumptions for estimated fair value of employee stock options
Expected term (years)	6 months	6 months	6 months	6 months
ESPP | Maximum
Weighted average assumptions for estimated fair value of employee stock options
Expected term (years)	2 years	2 years	2 years	2 years

Stock Based Compensation - Rest

Stock Based Compensation - Restricted stock units (Details) - Restricted stock units $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2020USD ($)$ / sharesshares
Stock-based compensation
Beginning balance | shares	90,006
Granted | shares	305,794
Vested | shares	(21,822)
Forfeited | shares	(7,311)
Ending balance | shares	366,667
Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	$ 34.66
Weighted Average Grant Date Fair Value, Granted | $ / shares	31.64
Weighted Average Grant Date Fair Value, Vested | $ / shares	31.91
Weighted Average Grant Date Fair Value, Forfeited | $ / shares	31.47
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 32.37
Compensation expense
Unamortized compensation expense related to unvested restricted stock units | $	$ 10,200
Period to recognize unamortized compensation expense	2 years 3 months 18 days

Leases (Details)

Leases (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jul. 31, 2017
Lessee, Lease, Description [Line Items]
Option to extend	true
For the remainder of 2020	$ 1,297
2021	2,583
2022	2,203
2023	1,347
2024	1,366
2025	1,212
Thereafter	1,238
Total undiscounted lease payments	11,246
Less: Imputed interest	(1,526)
Present value of lease payments	$ 9,720
Monrovia, CA - office and laboratory space
Lessee, Lease, Description [Line Items]
Lease term	66 months
Monrovia, CA - office and laboratory space with additional space
Lessee, Lease, Description [Line Items]
Renewal term		5 years
San Diego, CA - office space
Lessee, Lease, Description [Line Items]
Renewal term	5 years
San Diego, CA - second office space
Lessee, Lease, Description [Line Items]
Renewal term	5 years

Leases - Operating lease liabil

Leases - Operating lease liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Leases
Lease liability - short-term	$ 2,094	$ 2,169
Lease liability - long-term	7,626	$ 8,565
Operating lease liabilities	$ 9,720

Leases - Lease costs (Details)

Leases - Lease costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Leases
Operating lease cost	$ 648	$ 650	$ 1,297	$ 1,299
Variable lease cost	38	47	59	57
Total lease costs	686	697	1,356	1,356
Cash paid for amounts included in the measurement of lease liabilities	566	$ 344	1,123	$ 854
ROU assets exchanged for lease liabilities	$ 100		$ 100
Remaining lease term	5 years 2 months 12 days		5 years 2 months 12 days
Discount rate	5.50%		5.50%

Collaboration and Licensing A_3

Collaboration and Licensing Agreements (Details)	Feb. 04, 2020USD ($)shares	Mar. 29, 2019USD ($)	Mar. 08, 2019	Apr. 30, 2020USD ($)item	Mar. 31, 2020item	Feb. 29, 2020USD ($)	Jan. 31, 2020USD ($)item	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Feb. 28, 2019USD ($)	Oct. 31, 2017USD ($)shares	Jun. 30, 2016USD ($)item	Sep. 30, 2015USD ($)	Jan. 31, 2013Program	Jun. 30, 2006item	Jun. 30, 2020USD ($)	Sep. 30, 2019USD ($)item	Jun. 30, 2019USD ($)	Jun. 30, 2020USD ($)Optionitem	Jun. 30, 2019USD ($)	Jul. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Collaboration research and licensing agreements
Deferred revenue								$ 48,800,000								$ 44,700,000		$ 48,800,000	$ 44,700,000	$ 48,800,000
Revenue recorded																13,089,000		19,485,000	45,474,000	131,424,000
Current portion of deferred revenue								45,500,000								44,685,000		45,500,000	44,685,000	45,500,000		$ 45,205,000
Non Current portion of deferred revenue								3,300,000										3,300,000		3,300,000		$ 1,926,000
Licensing
Collaboration research and licensing agreements
Revenue recorded																7,500,000			23,100,000	111,600,000
Royalty
Collaboration research and licensing agreements
Revenue recorded																3,800,000		1,100,000	7,200,000	1,100,000
Milestone
Collaboration research and licensing agreements
Revenue recorded																300,000		4,000,000	12,800,000	4,000,000
Genentech
Collaboration research and licensing agreements
Revenue recorded																800,000		600,000	1,500,000	$ 112,500,000
Genentech | Maximum
Collaboration research and licensing agreements
Term of revenue recognized																				1 year
Astellas
Collaboration research and licensing agreements
Revenue recorded																700,000		13,800,000	$ 900,000	$ 13,800,000
Novartis
Collaboration research and licensing agreements
Number of performance obligations																			2
MorphoSys
Collaboration research and licensing agreements
Revenue recorded																			$ 12,500,000
Alexion
Collaboration research and licensing agreements
Revenue recorded																3,800,000		5,100,000	7,200,000	5,100,000
VIR Biotechnology
Collaboration research and licensing agreements
Revenue recorded																300,000			300,000
Aimmune
Collaboration research and licensing agreements
Revenue recorded																			9,600,000
Gilead
Collaboration research and licensing agreements
Revenue recorded																7,500,000			13,500,000
Collaboration and License Agreement | Genentech
Collaboration research and licensing agreements
Nonrefundable upfront payment										$ 120,000,000
Percentage of profits on net sales of the product										45.00%
Initial cost-sharing percentage			45.00%
Research license term										2 years
Revenue recognized																800,000		600,000	1,500,000	112,500,000
Collaboration and License Agreement | Genentech | XmAb24306
Collaboration research and licensing agreements
Cost sharing receivable (payable)																(1,300,000)			(1,300,000)
Collaboration and License Agreement | Genentech | Research service
Collaboration research and licensing agreements
Performance obligation										$ 8,300,000
Revenue recognized																800,000
Deferred revenue																4,600,000			4,600,000
Collaboration and License Agreement | Genentech | Licensing
Collaboration research and licensing agreements
Revenue recognized									$ 111,700,000
Collaboration and License Agreement | Genentech | Maximum
Collaboration research and licensing agreements
Potential milestone payment										$ 160,000,000
Collaboration and License Agreement | Novartis
Collaboration research and licensing agreements
Nonrefundable upfront payment												$ 150,000,000
Revenue recognized																0		0	0	0
Deferred revenue																40,100,000			40,100,000
Cost sharing receivable (payable)																1,000,000			$ 1,000,000
Collaboration and License Agreement | Novartis | Bispecific
Collaboration research and licensing agreements
Number of development stage products | item															2				1
Collaboration and License Agreement | Novartis | Discovery Program
Collaboration research and licensing agreements
Number of performance obligations | item																			2
Collaboration and License Agreement | Novartis | Bispecific FC Technologies
Collaboration research and licensing agreements
Number of development stage products | item												2
Collaboration and License Agreement | Novartis | Bispecific FC Technologies | Maximum
Collaboration research and licensing agreements
Number of antibody targets for which bispecific technology applied | item												4
Collaboration and License Agreement | Novartis | FC Licenses | Maximum
Collaboration research and licensing agreements
Number of targets against which non-exclusive license is provided | item												10
Collaboration and License Agreement | MorphoSys
Collaboration research and licensing agreements
Revenue recognized																0		0	$ 12,500,000	0
Deferred revenue																0			0
Collaboration and License Agreement | MorphoSys | Milestone
Collaboration research and licensing agreements
Revenue recognized						$ 12,500,000
Collaboration and License Agreement | MorphoSys | Forecast
Collaboration research and licensing agreements
Potential milestone payment																					$ 25,000,000
Research and License Agreement | Genentech | Research service
Collaboration research and licensing agreements
Revenue recognized																			1,500,000
Research and License Agreement | Astellas
Collaboration research and licensing agreements
Nonrefundable upfront payment		$ 15,000,000
Potential milestone payment		240,000,000
Revenue recognized																700,000		13,800,000	900,000	13,800,000
Deferred revenue																0			0
Research and License Agreement | Astellas | Bispecific
Collaboration research and licensing agreements
Revenue recognized								13,600,000
Research and License Agreement | Astellas | Research service
Collaboration research and licensing agreements
Performance obligation		1,400,000
Research and License Agreement | Amgen, Inc.
Collaboration research and licensing agreements
Upfront and milestone payment													$ 60,500,000
Potential milestone payment													$ 255,000,000
Revenue recognized																0		0	0	0
Deferred revenue																0			0
Research and License Agreement | VIR Biotechnology
Collaboration research and licensing agreements
Potential milestone payment																	$ 155,250,000
Revenue recognized																300,000		0	300,000	0
Deferred revenue																0			0
Number of different target programs | item																	2
Option and License Agreement | Alexion
Collaboration research and licensing agreements
Proceeds from milestone payments																		4,000,000
Revenue recognized																			7,200,000	5,100,000
Deferred revenue																0			0
Cost sharing receivable (payable)																7,400,000			7,400,000
Number of different target programs | Program														1
Option and License Agreement | Alexion | Royalty
Collaboration research and licensing agreements
Revenue recognized																3,800,000		1,100,000
License Agreement | INmune
Collaboration research and licensing agreements
Nonrefundable upfront payment											$ 100,000
Revenue recognized																0		0	0	0
Deferred revenue																0			0
Equity issued in shares | shares											1,585,000
Equity issues, value											$ 10,000,000
Option term											6 years
Carrying value								$ 0								0		$ 0	0	$ 0
License Agreement | INmune | Maximum
Collaboration research and licensing agreements
Additional equity interests (as a percentage)											10.00%
License Agreement | Gilead
Collaboration research and licensing agreements
Performance obligation							$ 13,500,000
Nonrefundable upfront payment							6,000,000
Potential milestone payment							$ 67,000,000									7,500,000			7,500,000
Revenue recognized				$ 7,500,000												7,500,000			13,500,000
Deferred revenue																0			$ 0
Options exercised				3	2														3
Number of compounds | item							3
Number of commercial licenses | item																			4
License Agreement | Gilead | Cytotoxic Fc and Xtend Fc Technologies
Collaboration research and licensing agreements
Performance obligation																3,500,000			$ 3,500,000
License Agreement | Gilead | Initial Option Exercises
Collaboration research and licensing agreements
Performance obligation																2,500,000			2,500,000
License, Development, and Commercialization Agreement | Aimmune
Collaboration research and licensing agreements
Performance obligation	$ 9,600,000
Nonrefundable upfront payment	5,000,000
Potential milestone payment	$ 385,000,000
Revenue recognized																0			9,600,000
Deferred revenue																$ 0			$ 0
Equity issued in shares | shares	156,238
Equity issues, value	$ 4,600,000
Development-based | Research and License Agreement | Astellas
Collaboration research and licensing agreements
Potential milestone payment		32,500,000
Development-based | Research and License Agreement | VIR Biotechnology
Collaboration research and licensing agreements
Potential milestone payment																	$ 5,250,000
Development-based | License Agreement | Gilead
Collaboration research and licensing agreements
Potential milestone payment							$ 10,000,000
Development-based | License, Development, and Commercialization Agreement | Aimmune
Collaboration research and licensing agreements
Potential milestone payment	22,000,000
Regulatory-based | Research and License Agreement | Astellas
Collaboration research and licensing agreements
Potential milestone payment		57,500,000
Regulatory-based | Research and License Agreement | VIR Biotechnology
Collaboration research and licensing agreements
Potential milestone payment																	30,000,000
Regulatory-based | License Agreement | Gilead
Collaboration research and licensing agreements
Potential milestone payment							27,000,000
Regulatory-based | License, Development, and Commercialization Agreement | Aimmune
Collaboration research and licensing agreements
Potential milestone payment	53,000,000
Sales-based | Research and License Agreement | Astellas
Collaboration research and licensing agreements
Potential milestone payment		$ 150,000,000
Sales-based | Research and License Agreement | VIR Biotechnology
Collaboration research and licensing agreements
Potential milestone payment																	$ 120,000,000
Sales-based | License Agreement | Gilead
Collaboration research and licensing agreements
Potential milestone payment							$ 30,000,000
Sales-based | License, Development, and Commercialization Agreement | Aimmune
Collaboration research and licensing agreements
Potential milestone payment	$ 310,000,000

Collaborative and Licensing Agr

Collaborative and Licensing Agreements - Revenue Recognition (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recorded	$ 13,089,000	$ 19,485,000	$ 45,474,000	$ 131,424,000
Deferred revenue	44,700,000	48,800,000	44,700,000	48,800,000
Current portion of deferred revenue	44,685,000	45,500,000	44,685,000	45,500,000	$ 45,205,000
Non Current portion of deferred revenue		3,300,000		3,300,000	$ 1,926,000
Research collaboration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recorded	1,500,000	14,400,000	2,400,000	14,700,000
Milestone
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recorded	300,000	4,000,000	12,800,000	4,000,000
Licensing
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recorded	7,500,000		23,100,000	111,600,000
Royalty
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recorded	3,800,000	1,100,000	7,200,000	1,100,000
Aimmune
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recorded			9,600,000
Alexion
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recorded	3,800,000	5,100,000	7,200,000	5,100,000
Astellas
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recorded	700,000	13,800,000	900,000	13,800,000
Genentech
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recorded	800,000	$ 600,000	1,500,000	$ 112,500,000
Gilead
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recorded	7,500,000		13,500,000
MorphoSys
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recorded			12,500,000
VIR Biotechnology
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recorded	300,000		$ 300,000
Novartis
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of performance obligations			2
Collaboration and License Agreement | MorphoSys
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue	0		$ 0
Collaboration and License Agreement | Novartis
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue	$ 40,100,000		$ 40,100,000
Minimum | Genentech
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Term of revenue recognized			1 year
Maximum | Genentech
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Term of revenue recognized				1 year

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Jun. 30, 2020	Dec. 31, 2019
Reconciliation of federal statutory income tax to effective income tax
Income tax expense	$ 50	$ 950
Federal
Reconciliation of federal statutory income tax to effective income tax
Income tax receivable			$ 800	$ 800