---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-26-229173"
form_type: "8-K"
ticker: "CGEM"
cik: "0001789972"
company_name: "Cullinan Therapeutics, Inc."
filed_at: "2026-05-18T21:30:08+00:00"
generated_at: "2026-05-18T21:32:59.253719+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.6
calibrated_materiality_score: 0.6
confidence: "high"
source: SEC EDGAR
---

# Cullinan reports initial Phase 1 data for CLN-978: B cell depletion and early efficacy in RA/SLE

## Summary
- As of Jan 14, 2026 cutoff, 14 patients dosed (5 RA, 9 SLE) across cohorts 1-3.
- B cell depletion >75% in 9/11 patients after 10 mcg; 3/6 below quantification after 20 mcg.
- 4/5 RA patients had DAS28-ESR decrease from high activity to moderate/remission.
- 5/6 SLE patients had SLEDAI score decrease >4 points; ultrasound synovitis improved in 3/4 RA.
- CLN-978 well tolerated; dose escalation continues; updated data at EULAR June 2026.

## SEC filing metadata
- accession: 0001193125-26-229173
- form_type: 8-K
- ticker: CGEM
- cik: 0001789972
- company_name: Cullinan Therapeutics, Inc.
- filed_at: 2026-05-18T21:30:08+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.6
- calibrated_materiality_score: 0.6
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1789972/000119312526229173/0001193125-26-229173-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1789972/000119312526229173/cgem-20260518.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-26-229173
- JSON: https://secwatch.observer/filing/0001193125-26-229173.json
- Plain text: https://secwatch.observer/filing/0001193125-26-229173.txt

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