CytomX announced positive Phase 1 expansion data for varsetatug masetecan (Varseta-M), an EpCAM PROBODY antibody-drug conjugate, in late-line metastatic colorectal cancer on March 16, 20262
The preliminary data are from the CTMX-2051-101 Phase 1 study with a data cutoff of January 16, 2026, including 93 patients with late-line metastatic CRC enrolled23
At the 10 mg/kg dose, the confirmed response rate was 32% with an estimated median progression-free survival of 7.1 months; at 8.6 mg/kg, the confirmed response rate was 20% with estimated median PFS of 6.8 months2
Disease control rate was 88% across the expansion doses of 7.2-10 mg/kg2
Grade 3 diarrhea rate was 10% in dose optimization cohorts, characterized as manageable and reversible2
Enrolled patients had previously received a median of 3 prior lines of therapy in the metastatic setting, with 96% previously treated with irinotecan2
CytomX plans FDA interactions targeted for mid-year 2026 to align on potential registrational trial design in late-line colorectal cancer2
The company is initiating a Phase 1 study evaluating combination with bevacizumab and planning to initiate a Phase 1b/2 chemotherapy combination study by end of 20262
Sources:
2. https://www.globenewswire.com/news-release/2026/03/16/3256138/37704/en/CytomX-s-Varsetatug-Masetecan-EpCAM-PROBODY-ADC-Continues-to-Demonstrate-Positive-Data-Supporting-Potential-as-a-New-Treatment-Option-in-Late-Line-Colorectal-Cancer.html
3. https://www.marketscreener.com/news/cytomx-therapeutics-inc-announces-positive-data-for-varsetatug-masetecan-in-late-line-colorectal-c-ce7e5edadc81f327