CytomX's Varseta-M shows breakthrough potential in colorectal cancer trials

CytomX Therapeutics has unveiled promising results for its experimental drug, Varseta-M, in treating colorectal cancer. The antibody drug conjugate, targeting the EpCAM protein, has shown strong response rates and improved survival estimates in early trials. The company now plans to accelerate its development with multiple studies set to begin by 2027.

In recent Phase I trials, Varseta-M demonstrated a 32% overall response rate at a 10 mg/kg dose and 20% at 8.6 mg/kg. Updated data also revealed progression-free survival estimates of 6.8 to 7.1 months, an improvement from the 5.8 months reported in May 2025. Unlike earlier EpCAM-targeting treatments, the drug has not produced the same toxic side effects, with only a 10% rate of grade 3 diarrhoea observed in early cohorts using updated preventative measures.

The company now aims to launch its first registrational study in the first half of 2027, with overall survival as the primary endpoint. Before then, CytomX plans to start combination studies with bevacizumab and chemotherapy by the end of 2026. Additionally, the drug's potential will be explored beyond colorectal cancer, with a first study in another tumour type expected later in the year.

CytomX has described Varseta-M as a key asset that could generate billions in revenue. Projections suggest up to 45,000 treatable patients in third-line colorectal cancer alone by 2040. Further data from the ongoing Phase I study will be shared in the second half of 2026.

Varseta-M's progress marks a significant step in CytomX's pipeline, with multiple trials and expansion plans underway. The drug's improved survival rates and manageable side effects position it as a potential major treatment option. The company's next updates will arrive in late 2026, ahead of the registrational study's launch in early 2027.