The site reports on new, positive Phase 1 data on Varsetatug Masetecan (Varseta-M)an EpCAM-targeted PROBODY® ADC from CytomX, which is being investigated as a potential new therapy for therapy for late-stage metastatic colorectal cancer (CRC). is being developed. ir.cytomx.com
Key results of the study
- Clinical efficacy
- 32 % confirmed response rate at 10 mg/kg Q3W.
- 20 % response rate at 8.6 mg/kg Q3W.
- Median progression-free survival (PFS):7.1 months (10 mg/kg)
- 6.8 months (8.6 mg/kg)
- Disease control rate: 88% across all expansion doses.
- Patients were heavily pretreated (median 3 prior therapies; 96 % irinotecan-pretreated).
- Safety profile
- Overall well manageablepredominantly Grade 1/2 side effects.
- Most common side effect: Diarrheamostly reversible.
- With new prophylaxis (loperamide/diphenoxylate + budesonide), grade 3 diarrhea decreased to Grade 3 diarrhea to 10 %.
- An earlier grade 5 case of acute renal failure at 7.2 mg/kg, but no further fatal events.
Significance of the results
- The data indicate a consistent and durable response in a patient in a patient group that otherwise has very limited options.
- Varseta-M could represent a new treatment option for late-treated CRC patients.
- EpCAM has been difficult to target because it also occurs on healthy tissue; the PROBODY® technology is expected to solve this problem.
Next steps for CytomX
- FDA discussions in mid-2026 for a possible registrational study (relevance for approval).
- Phase 1 combination study with bevacizumab already started.
- Phase 1b/2 combination with chemo + bevacizumab planned until the end of 2026.
- Expansion into further EpCAM-positive tumor types from 2H 2026.
- Further data presentations at medical congresses in 2026.
Company context
- CytomX develops masked, locally activated biologics (PROBODY® platform).
- Pipeline includes ADCs, cytokines and T-cell engagers.
- Varseta-M was jointly discovered with ImmunoGen (now AbbVie).
- Further programs: e.g. CX-801 (masked IFN-α2b) for metastatic melanoma.