Condensed Statements of Operations (Unaudited) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Revenues (including amounts from related parties of $0 and $2,813 during the three and six months ended June 30, 2020, respectively, and $5,497 and $10,413 during the three and six months ended June 30, 2019, respectively)	[1],[2]	$ 9,469	$ 10,525	$ 16,621	$ 19,154
Operating expenses
Research and development		17,243	16,143	34,862	31,323
General and administrative		8,643	8,067	17,356	15,782
Total operating expenses		25,886	24,210	52,218	47,105
Loss from operations		(16,417)	(13,685)	(35,597)	(27,951)
Interest income		384	1,124	1,025	2,300
Unrealized gain on equity securities		48,860		48,860
Interest and other expense, net		(2,955)	(1,232)	(4,011)	(2,392)
Net income (loss)		$ 29,872	$ (13,793)	$ 10,277	$ (28,043)
Net income (loss) per share, basic	[3]	$ 1.00	$ (0.60)	$ 0.39	$ (1.22)
Net income (loss) per share, diluted	[3]	$ 0.94	$ (0.60)	$ 0.36	$ (1.22)

[1] Includes $0 and $2.8 million, respectively, for the three months and six months ended June 30, 2020 of related party revenue from Merck. Merck was a related party until the closing of the Company’s public offering on May 14, 2020.

[2] Includes $0 and $36,000, respectively, for the three months and six months ended June 30, 2020 of related party revenue from Vaxcyte (formerly SutroVax). Vaxcyte was a related party until the closing of its initial public offering on June 16, 2020.

[3] See Notes 2 and 10 for an explanation of the calculations of our basic and diluted net income (loss) per share, basic and diluted and the weighted-average number of shares used in the computation of the per share amounts.