Pfizer has teamed up with Summit Therapeutics to assess whether one of the industry’s hottest cancer candidates works well with its antibody-drug conjugates (ADCs).
Miami-based Summit holds the rights to the PD-1xVEGF bispecific ivonescimab in territories including the U.S. and Europe. The biotech’s partner Akeso sent interest in the mechanism into the stratosphere in September, when ivonescimab beat Merck & Co.’s Keytruda in a midphase trial. Companies including BioNTech, Merck, Crescent Biopharma and Ottimo all later made or upped bets on the mechanism.
Ivonescimab remains the frontrunner, with Summit on track to report topline data from a phase 3 non-small cell lung cancer trial in the middle of 2025. The study is part of a broad clinical trial program that will soon be swelled further by ADC combination trials.
Summit is providing ivonescimab for use in trials run by Pfizer. Starting in mid-2025, the Big Pharma will kick off trials of Summit’s bispecific and its vedotin ADCs in individual, distinct solid tumor types. Vedotin is the payload in a clutch of ADCs that Pfizer acquired in the Seagen buyout, including the approved products Adcetris, Padcev and Tivdak.
Summit's stock price dropped by nearly 15% during Monday's trading. Investors were likely disappointed in the lack of a deep commitment from Pfizer given the relatively small scope of a trial collaboration compared with a licensing deal.
The combination trials could help future-proof ivonescimab. Chemotherapy remains part of the standard of care in many tumor types, leading Summit to include drugs such as carboplatin and pemetrexed in its phase 3 treatment regimens. Yet, ADC developers see the potential for their products to supplant chemo in cancer combinations and become part of the new standard of care.
An analyst queried Jack West, M.D., vice president of clinical development at Summit, about the biotech’s interest in combinations at an event in September. Noting that AstraZeneca and Merck are pairing PD-1 drugs with ADCs, the analyst asked if Summit was thinking about studying emerging combinations rather than just comparing ivonescimab to the historical standard of care. West left the door open to combos.
“Without giving any specific details, we're very interested. The safety profile of ivonescimab is such that it seems to be combinable with other products,” West said. “Our Akeso partners have done a wonderful job of developing it, combining it with multiple chemo regimens in their internal pipeline of novel bispecific and monoclonal antibodies, and it seems to be combinable with all of those agents.”
The Pfizer agreement positions Summit to find out if ADCs are among agents that ivonescimab plays well with. Pfizer and Summit are retaining the rights to their respective products and will both oversee the studies.
Editor's Note: The story was updated Feb. 25 to incorporate Summit's stock performance on Feb. 24.