Pfizer's experimental antibody-drug conjugate sigvotatug vedotin, acquired through its $43 billion Seagen buyout, failed to meet its primary endpoint in a Phase 2 trial for non-small cell lung cancer. The drug, which targets the protein integrin beta-6, showed disappointing efficacy compared to standard chemotherapy in patients with advanced or metastatic disease.
The open-label study enrolled patients who had received prior platinum-based chemotherapy and a checkpoint inhibitor. While specific efficacy and safety data have not yet been disclosed, the company stated the results did not reach statistical significance for progression-free survival. Pfizer noted the drug's safety profile was consistent with earlier studies.
Despite this setback, Pfizer plans to continue development of sigvotatug vedotin. The company is awaiting results from a separate Phase 2 trial in ovarian cancer, which some analysts believe could still demonstrate meaningful activity. A pivotal Phase 3 trial in lung cancer remains under discussion with regulators.
Pfizer has not revised its full-year revenue guidance, which includes expectations for Seagen-acquired medicines. The drug was forecast to contribute significantly to the company's oncology portfolio, though investor sentiment had already tempered following recent pipeline challenges. Shares dipped slightly in premarket trading.
Some analysts remain cautiously optimistic, noting that the drug's mechanism targeting integrin beta-6 is still unproven in large trials. The ovarian cancer readout, expected later this year, will be critical in determining whether the broader Seagen deal retains its strategic value for Pfizer.