---
schema_version: "secwatch.filing_event.v1"
accession: "0001104659-24-126758"
form_type: "8-K"
ticker: "RIGL"
cik: "0001034842"
company_name: "RIGEL PHARMACEUTICALS INC"
filed_at: "2024-12-09T23:59:59+00:00"
generated_at: "2026-05-29T05:27:31.559187+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.65
calibrated_materiality_score: 0.65
confidence: "high"
source: SEC EDGAR
---

# Rigel reports initial Phase 1b data for R289 in LR-MDS; 40% response rate in evaluable TD patients at ≥500 mg QD

## Summary
- 22 LR-MDS patients enrolled; median age 76, median 3 prior therapies; 73% high transfusion burden.
- R289 well tolerated; most common AEs diarrhea/fatigue (27%), chills/nausea/pruritus (23%), all Grade 1/2.
- Among evaluable TD patients at doses ≥500 mg QD, 40% (4/10) achieved RBC-TI/HI-E; 3 achieved RBC-TI ≥8 weeks.
- Two HTB patients achieved RBC-TI >24 weeks; median RBC-TI duration 29 weeks (range 12.7-51.9 weeks).
- FDA granted Fast Track designation for R289 in previously-treated transfusion-dependent LR-MDS.

## SEC filing metadata
- accession: 0001104659-24-126758
- form_type: 8-K
- ticker: RIGL
- cik: 0001034842
- company_name: RIGEL PHARMACEUTICALS INC
- filed_at: 2024-12-09T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.65
- calibrated_materiality_score: 0.65
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1034842/000110465924126758/0001104659-24-126758-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1034842/000110465924126758/tm2430504d1_8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001104659-24-126758
- JSON: https://secwatch.observer/filing/0001104659-24-126758.json
- Plain text: https://secwatch.observer/filing/0001104659-24-126758.txt

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