---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-24-134284"
form_type: "8-K"
ticker: "CTMX"
cik: "0001501989"
company_name: "CytomX Therapeutics, Inc."
filed_at: "2024-05-08T23:59:59+00:00"
generated_at: "2026-06-02T09:45:54.371145+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.7
calibrated_materiality_score: 0.7
confidence: "high"
source: SEC EDGAR
---

# CytomX reports positive Phase 1a data for CX-904: no CRS, 33% response rate in pancreatic cancer

## Summary
- CX-904 demonstrated favorable safety: no CRS of any grade in step-dosing; no Grade >1 CRS overall.
- In 6 efficacy-evaluable pancreatic cancer patients, 2 confirmed partial responses (33%) and all 6 had disease control.
- One patient achieved 83% tumor reduction at 6 mg; another 51% at 5 mg; both remained on treatment.
- Preliminary PK/PD data support PROBODY T-cell engager mechanism: maintained masking and CD8+ T-cell margination.
- Dose escalation continues; Phase 1b expansion in EGFR-positive tumors planned with partner Amgen.

## SEC filing metadata
- accession: 0001193125-24-134284
- form_type: 8-K
- ticker: CTMX
- cik: 0001501989
- company_name: CytomX Therapeutics, Inc.
- filed_at: 2024-05-08T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.7
- calibrated_materiality_score: 0.7
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1501989/000119312524134284/0001193125-24-134284-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1501989/000119312524134284/d835346d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-24-134284
- JSON: https://secwatch.observer/filing/0001193125-24-134284.json
- Plain text: https://secwatch.observer/filing/0001193125-24-134284.txt

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