---
schema_version: "secwatch.filing_event.v1"
accession: "0000950170-22-018936"
form_type: "8-K"
ticker: "RLYB"
cik: "0001739410"
company_name: "Rallybio Corp"
filed_at: "2022-09-28T23:59:59+00:00"
generated_at: "2026-06-23T07:00:28.449866+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.65
calibrated_materiality_score: 0.65
confidence: "high"
source: SEC EDGAR
---

# Rallybio: RLYB212 Phase 1b rapidly eliminates HPA-1a platelets; proof-of-concept data Q1 2023

## Summary
- RLYB212 showed >90% reduction in mean platelet elimination half-life vs placebo in Phase 1b.
- Single subcutaneous dose eliminated transfused HPA-1a positive platelets rapidly one week after dosing.
- No serious adverse events; safety and tolerability acceptable.
- Protocol amended to increase dose and expand PK/PD sampling; registrational trial dosing expected to be informed.
- Proof-of-concept data from Phase 1b study expected in Q1 2023.

## SEC filing metadata
- accession: 0000950170-22-018936
- form_type: 8-K
- ticker: RLYB
- cik: 0001739410
- company_name: Rallybio Corp
- filed_at: 2022-09-28T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.65
- calibrated_materiality_score: 0.65
- confidence: high
- sec_items: 7.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1739410/000095017022018936/0000950170-22-018936-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1739410/000095017022018936/rlyb-20220928.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000950170-22-018936
- JSON: https://secwatch.observer/filing/0000950170-22-018936.json
- Plain text: https://secwatch.observer/filing/0000950170-22-018936.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.