Just weeks after Pfizer’s Seagen-acquired antibody-drug conjugate sigvotatug vedotin failed a Phase 3 non-small cell lung cancer study, the big pharma has quietly culled another program being developed by the ADC specialist.
Pfizer is scrapping an antibody-drug conjugate designed to treat advanced solid tumors, terminating a Phase 1 trial evaluating the drug coded SGN-MesoC2.
“We are no longer developing SGN-MesoC2 and the decision was due to business reasons, reflecting a strategic prioritization of resources toward programs we believe will deliver the greatest impact for patients,” a spokesperson told BioSpace on Wednesday via email.
The terminated open-label trial launched in 2024 and had enrolled 19 patients, according to ClinicalTrials.gov. The study discontinuation was not related to safety, according to the site.
SGN-MesoC2, also known as PF-08052666 or HBM9033, was designed to be a first-in-class antibody. Initially developed by Harbour BioMed (Nona Biosciences), SGN-MesoC2 was licensed to Pfizer for $53 million in upfront and near-term payments at the end of 2023—just hours after the pharma closed its $43 billion Seagen buyout. The mesothelin-targeted ADC’s trial was run by Seagen under the Pfizer umbrella. Pfizer had made the decision to purchase the biotech for its approved drugs, ADC platform and pipeline.
As of publication, Pfizer has not responded to BioSpace’s inquiry about potential workforce changes associated with the pipeline cull.
The quiet discontinuation follows the loud and disappointing miss of sigvotatug vedotin, Seagen’s investigational ADC that failed to improve overall survival compared to the chemotherapy docetaxel in a Phase 3 study of advanced non-squamous non-small cell lung cancer. Despite the disappointing readout, Pfizer said it would continue to test the asset in the indication and for other solid tumors.
At the time, Leerink Partners said sigvotatug vedotin showed “promising” signals of efficacy in a subgroup of patients who had undergone only one prior line of treatment. The analysts said they believe the drug “still has a chance to succeed” in combination with Merck’s PD-1 inhibitor Keytruda as a first-line NSCLC option.
