Astellas is pulling out of its $1.6 billion biobucks partnership with CytomX Therapeutics six years after the two companies set out to explore T-cell-engaging bispecifics for the treatment of solid tumors.
The Bay Area-based biotech teamed up with the Japanese pharma back in 2020 to collaborate on CytomX’s Probody T-cell engager (TCE) platform, bispecific formats and CD3 modules. The deal saw CytomX receive an upfront payment of $80 million, with the potential for $1.6 billion to follow in milestones.
But the bulk of those milestone payments will now be forever out of reach, after CytomX revealed in its full-year earnings release Monday that Astellas has chosen not to advance the remaining preclinical assets, effectively calling time on the partnership.
At times, the collaboration had shown promise. Across March and April 2024, CytomX announced that a pair of T-cell bispecifics from the partnership had been nominated for further development, triggering a combined $10 million payday for the biotech.
Cytom X still has ongoing partnerships with the likes of Bristol Myers Squibb, Amgen, Regeneron and Moderna.
But the end of the Astellas pact comes after a difficult couple of years for CytomX. In March 2024, BMS stepped away from the checkpoint inhibitor portion of its own agreement with CytomX, wiping off $300 million in potential deal value after the partners had advanced a candidate into a phase 1/2 trial.
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In January 2025, CytomX laid off 40% of its workforce to focus resources on its lead antibody-drug conjugate (ADC). According to CEO Sean McCarthy today, the company’s “top priority” this year is to align with the FDA on a registrational path for that ADC, called varsetatug masetecan, for metastatic colorectal cancer. The asset includes a topoisomerase-1 inhibitor payload licensed from ImmunoGen.
CytomX entered 2026 with $137.1 million in cash and equivalents, which the company expects to last through the second quarter of 2027.
