The Company’s stock option awards generally vest over four years and typically have a contractual life of ten years. At March 31, 2021, there was $10.1 million of unrecognized compensation cost related to stock options, which is expected to be recognized over a weighted-average period of 2.9 years. During the three months ended March 31, 2021, the Company granted 669,000 stock options with a weighted average exercise price of $16.73 and per share weighted average grant date fair value of $13.76.

Information related to stock options outstanding at March 31, 2021 is as follows:

	Number of Stock Options		Weighted- average Exercise Price		Weighted- average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding		2,293,367	$	8.11		6.0	$	16,651,695
Exercisable		773,781	$	5.35		5.8	$	7,855,753
Unvested		1,519,586	$	9.51		6.0	$	8,795,942

Restricted Stock

At March 31, 2021, the Company had unvested restricted stock of 134,545 shares with total unrecognized compensation expense of $0.5 million, which the Company expects to recognize over a weighted average period of approximately 1.7 years. During the three months ended March 31, 2021, the Company released 20,181 shares of common stock from restriction as a result of the vesting of restricted stock.

In February 2021, the Company granted 181,279 shares of restricted stock units which vest over four years. At March 31, 2021, the Company had unvested restricted stock units of 196,279 shares with total unrecognized compensation expense of $2.8 million, which the Company expects to recognize over a weighted average period of approximately 3.8 years.

2019 Employee Stock Purchase Plan

Under the Employee Stock Purchase Plan, employees purchased 8,733 shares for $0.1 million during the three months ended March 31, 2021. During the three months ended March 31, 2021, the Company recognized compensation expense of $0.1 million.

Stock-based Compensation Expense

Stock-based compensation expense is classified in the unaudited consolidated statements of operations and comprehensive loss for the three months ended March 31, 2021 and 2020 as follows:

	For the Three Months Ended March 31,
	2021		2020
Research and development	$	321,338	$	29,000
General and administrative		897,013		185,921
Total	$	1,218,351	$	214,921