A closely watched, experimental cancer drug Pfizer sees as a key revenue contributor in the future has failed a key clinical trial in lung cancer.
Pfizer said Monday that the therapy, an antibody-drug conjugate called sigvotatug vedotin, didn’t significantly extend survival compared to a common chemotherapy in a Phase 3 study in people with advanced, non-squamous non-small cell lung cancer. The company didn’t provide specifics, only noting that they’ll be presented at a future medical meeting.
The readout represents a notable setback for a drug involved in Pfizer’s $43 billion buyout of ADC specialist Seagen. Pfizer has been looking to oncology, and the ADCs it inherited in that deal, as a important source of revenue growth in the years ahead. But the company has already recorded about $4.5 billion in write-offs related to development setbacks, emerging competition, and lower commercial expectations, wrote RBC Capital Markets analyst Trung Huynh, in a Monday client note. Sigvotatug vedotin’s study failure is “unlikely to help confidence” in the Seagen deal and could result in another impairment charge, he added.
Still, Pfizer is optimistic about sigvotatug vedotin, an ADC aimed at the “integrin beta-6” protein expressed on about 90% of tumors. One closely watched study is evaluating the drug alongside Merck & Co.’s Keytruda in first-line lung cancer. Expected to produce results in 2027, that study is one of several industry trials testing a regimen that could challenge regimens widely used in advanced lung cancer.
The bar for success is high. A different kind of ADC from Gilead Sciences failed in the first-line setting, and AstraZeneca and Daiichi Sankyo’s Datroway obtained narrower-than-expected use in second-line lung cancer following disappointing study results. An ongoing study is evaluating Datroway in newly diagnosed patients, and a highly anticipated trial of a dual-targeting drug from Akeso and Summit Therapeutics could soon produce results.
In its statement, Pfizer pointed to a “stronger trend” on survival as well as tumor progression in patients who’d previously received only one line of treatment, as opposed to more than one. That apparent benefit “reinforces our confidence” in the sigvotatug vedotin’s potential, including its prospects in that all-important study in first-line lung cancer, said Chief Oncology Officer Jeff Legos, in the statement.
Pfizer management has previously said that the first-line study might have a better shot at success based on the patients enrolled, wrote David Risinger, an analyst at Leerink Partners. Pfizer’s drug “still has a chance” there, he added, also noting that that trial has a different comparator — Keytruda rather than the chemotherapy docetaxel.
RBC’s Huynh added, meanwhile, that Monday’s negative readout eliminates one of two major potential catalysts for Pfizer this year. A second, of the drug mevrometostat in prostate cancer, is now the “sole remaining binary event this year and carries heightened importance for the growth narrative,” he wrote.
