Astellas Ends Partnership with CytomX Despite Positive Phase 1 Data for Probody Platform

Astellas Pharma terminated its collaboration with CytomX Therapeutics effective Q2 2026, choosing not to advance remaining preclinical programs despite positive early data124

The 2020 partnership provided CytomX $80 million upfront with potential for $1.6 billion in milestones and royalties for Probody-based bispecific antibodies in solid tumors12

CytomX's lead asset varsetatug masetecan (Varseta-M) showed 32% confirmed response rate, 7.1 months median PFS, and 84% disease control rate in Phase 1 metastatic CRC at 10 mg/kg dose14

CytomX maintains partnerships with Regeneron, Amgen, Bristol Myers Squibb, and Moderna, and reported $137.1 million cash lasting to Q2 2027234

Ongoing Varseta-M trials include Phase 1 with bevacizumab and planned Phase 1b/2 with bevacizumab plus chemotherapy by end of 202614

Sources:

1. https://www.biospace.com/business/astellas-divorces-cytomx-despite-positive-phase-1-data-for-antibody-platform

2. https://www.fiercebiotech.com/biotech/astellas-ends-16-billion-t-cell-engager-discovery-pact-cytomx

3. https://marketchameleon.com/articles/b/2026/3/16/cytomx-2025-results-strong-financial-position-pipeline-advances

4. https://natlawreview.com/press-releases/cytomx-therapeutics-announces-2025-financial-results-and-provides-business