---
schema_version: "secwatch.filing_event.v1"
accession: "0001628280-25-042245"
form_type: "8-K"
ticker: "CCCC"
cik: "0001662579"
company_name: "C4 Therapeutics, Inc."
filed_at: "2025-09-22T23:59:59+00:00"
generated_at: "2026-05-17T05:58:48.873067+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# C4 Therapeutics Phase 1 cemsidomide shows 50% ORR at 100 µg in RRMM; Phase 2 planned Q1 2026

## Summary
- 50% ORR at 100 µg and 40% ORR at 75 µg cemsidomide + dex in heavily pre-treated RRMM; median DOR 9.3 mo overall.
- No cemsidomide-related discontinuations; minimal dose reductions (6%); low rates of febrile neutropenia (4% Grade 3, 1% Grade 4).
- Phase 2 single-arm registrational trial in 4th line+ starts Q1 2026; Phase 1b with BCMA BiTE in 2nd line+ starts Q2 2026.
- 72 patients enrolled; median 7 prior therapies; 75% had prior CAR-T or T-cell engager therapy; data cutoff July 23, 2025.

## SEC filing metadata
- accession: 0001628280-25-042245
- form_type: 8-K
- ticker: CCCC
- cik: 0001662579
- company_name: C4 Therapeutics, Inc.
- filed_at: 2025-09-22T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1662579/000162828025042245/0001628280-25-042245-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1662579/000162828025042245/cccc-20250922.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001628280-25-042245
- JSON: https://secwatch.observer/filing/0001628280-25-042245.json
- Plain text: https://secwatch.observer/filing/0001628280-25-042245.txt

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