---
schema_version: "secwatch.filing_event.v1"
accession: "0001628280-26-042365"
form_type: "8-K"
ticker: "CCCC"
cik: "0001662579"
company_name: "C4 Therapeutics, Inc."
filed_at: "2026-06-11T11:04:42+00:00"
generated_at: "2026-06-11T11:10:24.251832+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# C4T Phase 1 cemsidomide in RRMM shows 53% ORR at RP2D, MRD negativity, well-tolerated

## Summary
- 53% ORR at 100 µg RP2D; 36% ORR across all doses (73 patients, median 7 prior lines).
- MRD negativity achieved in two patients at RP2D (sCR and CR); responses deepened over time.
- Median PFS 3.9 months (95% CI 3.2–5.6); median DOR 7.9 months (95% CI 3.0–NE).
- No treatment discontinuations related to cemsidomide; manageable neutropenia (58% Grade 3/4).
- ORR consistent across subgroups: prior CAR-T/TCE 53% at RP2D; prior BCMA 47% at RP2D.

## SEC filing metadata
- accession: 0001628280-26-042365
- form_type: 8-K
- ticker: CCCC
- cik: 0001662579
- company_name: C4 Therapeutics, Inc.
- filed_at: 2026-06-11T11:04:42+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.75
- calibrated_materiality_score: 0.75
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1662579/000162828026042365/0001628280-26-042365-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1662579/000162828026042365/cccc-20260611.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001628280-26-042365
- JSON: https://secwatch.observer/filing/0001628280-26-042365.json
- Plain text: https://secwatch.observer/filing/0001628280-26-042365.txt

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