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BUSINESS AND LIQUIDITY (Details) - USD ($) $ in Thousands |  | 3 Months Ended | 6 Months Ended |
--- | --- | --- | --- | ---
May 04, 2026 | Jun. 30, 2026 | Jun. 30, 2025 | Jun. 30, 2026 | Jun. 30, 2025 | May 31, 2026
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |
Termination fee |  | $ 50,000 | $ 0 | $ 50,000 | $ 0 |
Cash, cash equivalents and marketable securities |  | $ 92,800 |  | $ 92,800 |  |
Pre-Merger Equityholders of Avenzo |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |
Merger valuation amount |  |  |  |  |  | $ 300,000
Rallybio |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |
Concurred financing |  |  |  |  |  | $ 215,000
Rallybio | Pre-Merger Equityholders of Avenzo |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |
Merger and reorganization, combined ownership percentage |  |  |  |  |  | 56.60%
Avenzo Therapeutics, Inc | Pre-Merger Equityholders of Avenzo |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |
Merger and reorganization, combined ownership percentage |  |  |  |  |  | 2.80%
Concurrent Financing | Pre-Merger Equityholders of Avenzo |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |
Merger and reorganization, combined ownership percentage |  |  |  |  |  | 40.60%
Pre-Merger Equityholders of Rallybio | Rallybio |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |
Merger valuation amount |  |  |  |  |  | $ 15,000
Rallybio |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |
Termination fee | $ 50,000 |  |  |  |  |
Reimbursement of transaction costs | $ 400 |  |  |  |  |
Avenzo Therapeutics, Inc |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |
Concurred financing |  |  |  |  |  | $ 215,000

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