---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-22-188577"
form_type: "8-K"
ticker: "CTMX"
cik: "0001501989"
company_name: "CytomX Therapeutics, Inc."
filed_at: "2022-07-06T23:59:59+00:00"
generated_at: "2026-06-24T20:44:51.111704+00:00"
event_type: "other_material"
sentiment: "negative"
materiality_score: 0.7
calibrated_materiality_score: 0.7
confidence: "high"
source: SEC EDGAR
---

# CytomX Phase 2 breast cancer study: Arm A meets ORR endpoint but Arm B fails; program paused, partnership sought

## Summary
- Arm A in HR+/HER2- breast cancer met primary endpoint: ORR 15% (central review) in 47 patients unselected for CD166 expression.
- Arm B (TNBC) did not pass futility boundary (ORR <10%); enrollment in Arms B and C discontinued.
- Safety: 30% discontinued for AE; Grade 3+ ocular 15%, neuropathic 10%. Lower toxicity at 6 mg/kg dose.
- Company will not further advance program alone due to financial market conditions; seeking a partnership.
- CytomX intends to present full Phase 2 data at a medical conference in H2 2022.

## SEC filing metadata
- accession: 0001193125-22-188577
- form_type: 8-K
- ticker: CTMX
- cik: 0001501989
- company_name: CytomX Therapeutics, Inc.
- filed_at: 2022-07-06T23:59:59+00:00
- event_type: other_material
- sentiment: negative
- materiality_score: 0.7
- calibrated_materiality_score: 0.7
- confidence: high
- sec_items: 8.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1501989/000119312522188577/0001193125-22-188577-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1501989/000119312522188577/d259130d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-22-188577
- JSON: https://secwatch.observer/filing/0001193125-22-188577.json
- Plain text: https://secwatch.observer/filing/0001193125-22-188577.txt

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