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Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Summary of Fair Value Measurement Financial Assets

Financial assets measured at fair value on a recurring basis were as follows (in thousands):

			Fair Value Measurement at December 31, 2020
									Quoted Prices in Active Markets for Identical Assets						Significant Other Observable Inputs						Significant Unobservable Inputs
			Total						Level 1						Level 2						Level 3
Assets:
Money market funds			$	49,004					$	49,004					$	—					$	—
U.S Treasury securities			60,623						—						60,623						—
Corporate debt securities			33,776						—						33,776						—
Total assets measured at fair value (a)			$	143,403					$	49,004					$	94,399					$	—

			Fair Value Measurement at December 31, 2019
									Quoted Prices in Active Markets for Identical Assets						Significant Other Observable Inputs						Significant Unobservable Inputs
			Total						Level 1						Level 2						Level 3
Assets:
Money market funds			$	46,149					$	46,149					$	—					$	—
Government-sponsored enterprises			13,222						—						13,222						—
Corporate debt securities			103,135						—						103,135						—
Total assets measured at fair value (b)			$	162,506					$	46,149					$	116,357					$	—

(a) Total assets measured at fair value at December 31, 2020 includes approximately $52.0 million reported in cash and cash equivalents on the balance sheet.

(b) Total assets measured at fair value at December 31, 2019 includes approximately $73.2 million reported in cash and cash equivalents on the balance sheet.

Summary of Percentage of Customer Concentration

The following table includes those collaborators that represent more than 10% of total revenue earned in the periods indicated:

			Year Ended December 31,
			2020						2019						2018
Incyte Corporation (Incyte)			47%						35%						68%
Janssen Biotech, Inc. (Janssen)			19%						*						*
Zai Lab Limited (Zai Lab)			11%						29%						*
Les Laboratoires Servier and Institut de Recherches Servier (Servier)			*						18%						*

* Balance is less than 10%

The following table includes those counterparties that represent more than 10% of accounts receivable at the date indicated:

			December 31,
			2020						2019
Janssen			87%						*
Incyte			*						62%
Zai Lab			*						23%

Estimated Useful Lives

Depreciation and amortization are computed using the straight-line method over the following estimated useful lives:

Computer equipment			3 years
Software			3 years
Furniture			10 years
Laboratory and office equipment			5 years
Leasehold improvements			Shorter of lease term or useful life

Schedule of Stock Options and RSUs Excluded from the Calculation of Net Loss Per Share

The following table presents the number of stock options and RSUs that were excluded from the calculation of net loss per share:

			Year Ended December 31,
			2020						2019						2018
Stock options and RSUs			7,467,603						7,159,494						5,273,964

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