Pfizer's experimental lung cancer drug fails to extend survival in late-stage trial

Pfizer (PFE) has said that an experimental cancer drug acquired through its $43bn takeover of Seagen in 2023 failed to extend survival compared with chemotherapy in a late-stage trial of previously treated lung cancer patients, denting hopes for one of the assets underpinning the group's oncology pivot.

The drug, sigvotatug vedotin, did not achieve a statistically significant improvement in overall survival, the study's primary endpoint, among adults with locally advanced, unresectable or metastatic non-squamous non-small cell lung cancer, when measured against the chemotherapy docetaxel. Pfizer shares fell more than 1 percent in after-hours trading following the announcement.

Despite the setback, Pfizer said it remained confident in the drug's potential, pointing to a stronger survival trend among patients who had received only one prior line of therapy, along with encouraging early-stage data from a combination trial with Merck's (MRK) Keytruda. The company's chief oncology officer said the subgroup data showed favorable trends in both progression-free and overall survival, suggesting the drug is active and that its payload is reaching cancer cells directly.

Pfizer already has an ongoing late-stage trial testing the drug alongside Keytruda as a first-line treatment, and said it plans to explore combinations with other experimental therapies in its pipeline.

Sigvotatug vedotin targets integrin beta-6, a protein expressed in various solid tumors. Pfizer said the trial found no clear relationship between the level of protein expression in tumors and patients' response to treatment.

The Seagen deal gave Pfizer a portfolio of targeted therapies known as antibody-drug conjugates, a class the company has been counting on to help offset steep declines in COVID-19 product sales and generic competition facing several of its top-selling drugs. Pfizer said it continues to develop other ADCs, including some that also target integrin beta-6.

Pfizer shares have fallen more than 50 percent since early 2023 as the drugmaker has struggled to convince investors it can replace pandemic-era revenue with new growth drivers.