Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Net operating loss carryforwards	$ 75,005	$ 67,043
Capitalized research and development costs	16,911	0
Orphan drug credit carryforwards	14,628	6,679
Research and development credit carryforwards	10,140	8,774
Intangible assets	6,918	6,192
Accrued expenses and other	5,232	4,537
Operating lease liability	3,613	0
Deferred revenue	251	1,061
Deferred lease incentive	0	832
Deferred rent	0	471
Gross deferred tax assets	132,698	95,589
Valuation allowance	(129,512)	(94,630)
Net deferred tax assets	3,186	959
Deferred tax liability	(3,186)	(959)
Net deferred tax assets	$ 0	$ 0