---
schema_version: "secwatch.filing_event.v1"
accession: "0001104659-25-119976"
form_type: "8-K"
ticker: "RIGL"
cik: "0001034842"
company_name: "RIGEL PHARMACEUTICALS INC"
filed_at: "2025-12-10T23:59:59+00:00"
generated_at: "2026-05-16T13:36:59.479912+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.65
calibrated_materiality_score: 0.65
confidence: "high"
source: SEC EDGAR
---

# Rigel reports R289 Phase 1b data: 33% RBC-TI in evaluable lower-risk MDS patients

## Summary
- 33 patients enrolled (median age 75, median 3 prior therapies); 61% high transfusion burden at baseline.
- 6/18 evaluable transfusion-dependent patients at doses ≥500 mg QD achieved RBC-TI >8 weeks; median duration 22.9 weeks.
- R289 generally well tolerated; most common Grade 3/4 AEs: anemia (18%), neutropenia and pneumonia (each 15%).
- Dose expansion phase ongoing; RP2D selection expected H2 2026.
- R289 granted FDA Orphan Drug and Fast Track designations for MDS.

## SEC filing metadata
- accession: 0001104659-25-119976
- form_type: 8-K
- ticker: RIGL
- cik: 0001034842
- company_name: RIGEL PHARMACEUTICALS INC
- filed_at: 2025-12-10T23:59:59+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/1034842/000110465925119976/0001104659-25-119976-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1034842/000110465925119976/tm2533140d1_8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001104659-25-119976
- JSON: https://secwatch.observer/filing/0001104659-25-119976.json
- Plain text: https://secwatch.observer/filing/0001104659-25-119976.txt

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