Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2022

Equity [Abstract]

Summary of Stock Option Activity

The following table summarizes stock option activity as of December 31, 2022:

	​Number of shares			​Weighted average exercise price		Weighted average contractual term		​Aggregate intrinsic value
Outstanding at December 31, 2021		5,090,377		$	28.89
Granted		2,222,866			38.62
Exercised		(340,149	)		18.38
Forfeited		(317,942	)		39.50
Expired		(37,424	)		54.76
Outstanding at December 31, 2022		6,617,728		$	31.80		7.3	$	300,653,467
Vested and expected to vest at December 31, 2022		6,617,728		$	31.80		7.3	$	300,653,467
Exercisable at December 31, 2022		3,470,813		$	21.43		5.8	$	193,768,216

Summary of Black-Scholes Option Valuation Assumptions

The relevant data used to determine the value of the stock option grants for the years ended December 31, 2022, 2021, and 2020 is as follows:

Black-Scholes option valuation assumptions	2022		2021		2020
Risk-free interest rates	1.46 - 4.31%		0.63 - 1.47%		0.3 - 1.7%
Dividend yield		—		—		—
Volatility	90 - 95%		89 - 93%		67 - 99%
Weighted average expected term	5.0 - 6.11 years		5.0 - 6.17 years		3.51 - 6.14 years

Schedule of RSU Activity

The following table sets forth the RSU activity for the year ended December 31, 2022:

	Number of shares			Weighted average grant date fair value
Outstanding at December 31, 2021		302,764		$	42.93
Granted		533,134			27.18
Vested		(81,639	)		42.49
Forfeited		(67,884	)		30.20
Outstanding at December 31, 2022		686,375		$	31.80

Schedule of Stock-Based Compensation Expense Recognized

Stock‑based compensation expense recognized for the years ended December 31, 2022, 2021, and 2020 was as follows:

	Year ended December 31,
	2022		2021		2020
Research and development	$	8,604,408	$	7,456,049	$	3,953,939
Selling, general and administrative		29,121,750		13,345,331		10,802,267
Total	$	37,726,158	$	20,801,380	$	14,756,206