Accrued Expenses

6 Months Ended

Jun. 30, 2021

Payables and Accruals [Abstract]

Accrued Expenses

9. Accrued Expenses

A summary of the components of accrued expenses is as follows (in thousands):

	June 30, 2021		December 31, 2020
Accrued payroll	$	6,411	$	686
Accrued professional fees		607		468
Accrued other		14		254
Accrued vendor expenses		18,385		—
Accrued legal cost		—		6,000
Total accrued expenses	$	25,417	$	7,408

As of June 30, 2021, accrued expenses include amounts owed to vendors but not yet invoiced in exchange for vendor purchases and research and development services and statutory withholdings for cash payments due to payroll tax agencies related to stock option exercises near the end of June 2021. Vendor purchases and research and development services are invoiced and included in accounts payable as of December 31, 2020. Certain estimates of accrued vendor expenses are based on actual costs incurred to date compared to expected total costs.