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Commitments and Contingencies - Additional Information (Detail)		3 Months Ended		12 Months Ended
	Nov. 04, 2021 ft²	Mar. 31, 2022 USD ($) ft² Milestone	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($) Milestone	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2015 USD ($)
Other Commitments [Line Items]
Rental expense		$ 100,000	$ 100,000
Indemnification obligations amount		0
Contingent Liabilities		$ 0
Office of Chief Scientist of Israeli Ministry of Economy and Industry [Member]
Other Commitments [Line Items]
Grants received							$ 500,000
ALS Therapy Development Foundation, Inc. License Agreement [Member]
Other Commitments [Line Items]
Fee due for milestones achieved					$ 1,000,000.0	$ 1,000,000.0
Common stock issued in lieu of making a cash payment					$ 1,000,000.0	$ 1,000,000.0
Number of Milestones Achieved | Milestone		0		0
Remaining milestone payments for first licensed product		$ 6,000,000.0
Annual License Maintenance Fee				$ 100,000
ALS Therapy Development Foundation, Inc. License Agreement [Member] | Achievement of 500 Million Aggregate Sales [Member]
Other Commitments [Line Items]
Reaching of aggregate net sales		500,000,000.0
Amount of one-time milestone payment		15,000,000.0
ALS Therapy Development Foundation, Inc. License Agreement [Member] | Achievement of 1 Billion Aggregate Sales [Member]
Other Commitments [Line Items]
Reaching of aggregate net sales		1,000,000,000.0
Amount of one-time milestone payment		$ 30,000,000.0
Minimum [Member]
Other Commitments [Line Items]
Remaining term of office lease		9 months
Maximum [Member]
Other Commitments [Line Items]
Remaining term of office lease		3 years
Maximum [Member] | ALS Therapy Development Foundation, Inc. License Agreement [Member]
Other Commitments [Line Items]
Development and regulatory milestone payments		$ 2,500,000
Irvine, California [Member]
Other Commitments [Line Items]
Area of office space | ft²		5,197
Lease expiration date		Dec. 31, 2022
Burlington, Massachusetts [Member]
Other Commitments [Line Items]
Area of office space | ft²	6,138
Lease expiration date	Nov. 20, 2024

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