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STOCK-BASED COMPENSATION - Stock Option Activity (Details) - Common stock options - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Number of Shares Outstanding, Beginning Balance	7,686,233
Number of Shares, Granted	1,820,000
Number of Shares, Cancelled / Expired	(117,082)
Number of Shares Outstanding, Ending Balance	9,389,151	7,686,233
Number of Shares, Options vested and exercisable	4,798,325
Weighted Average Exercise Price per Share Outstanding, Beginning Balance	$ 5.47
Weighted Average Exercise Price per Share, Granted	0.51
Weighted Average Exercise Price per Share, Cancelled / Expired	2.60
Weighted Average Exercise Price per Share Outstanding, Ending Balance	4.54	$ 5.47
Weighted Average Exercise Price, Options vested and exercisable	$ 6.48
Weighted Average Remaining Contractual Life, Outstanding	7 years 10 months 24 days	7 years 8 months 12 days
Weighted Average Remaining Contractual Life, Options granted	9 years 9 months 18 days
Weighted Average Remaining Contractual Life, Options vested and exercisable	7 years 1 month 6 days

X

- Definition

Weighted average remaining contractual term for vested portions of options granted in period.

+ References

No definition available.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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- Definition

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for fully vested and expected to vest exercisable or convertible options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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