Key Takeaways:
Pfizer's experimental antibody-drug conjugate sigvotatug vedotin failed to improve overall survival versus docetaxel in a Phase 3 trial of adults with previously treated metastatic non-squamous non-small cell lung cancer.
"Although the overall study results did not demonstrate superiority over docetaxel, it is encouraging that second-line patients treated with sigvotatug vedotin achieved strong efficacy outcomes compared to an established standard of care," Jeff Legos, Chief Oncology Officer at Pfizer, said.
The SigVie-002 study enrolled 703 adults with locally advanced, unresectable or metastatic non-squamous NSCLC who had received one or more prior lines of systemic therapy. In the overall population, sigvotatug vedotin did not show a statistically significant improvement in the primary endpoint of overall survival compared with docetaxel. The safety profile was manageable and consistent with prior studies. In an exploratory analysis, no clear relationship between integrin beta-6 expression and response was observed.
The miss is a setback for Pfizer's ADC ambitions in lung cancer, though the company pointed to a subgroup of patients who received only one prior line of therapy — representing two-thirds of the study population — where a stronger trend for both overall survival and progression-free survival was observed. Pfizer is pressing ahead with an ongoing Phase 3 trial evaluating sigvotatug vedotin in combination with Merck's Keytruda (pembrolizumab) in first-line advanced NSCLC patients with PD-L1 tumor proportion scores of 50 percent or higher.
Integrin beta-6, the target of sigvotatug vedotin, is expressed on approximately 90 percent of NSCLC tumors and is associated with poor prognosis. The ADC was designed for high target selectivity of IB6 and rapid internalization to limit binding to other integrins expressed in normal tissues, potentially reducing off-target toxicity.
Solange Peters, Chair of Medical Oncology and Thoracic Cancers Clinic at Lausanne University Hospital in Switzerland, said the ability of sigvotatug vedotin to induce immunogenic cell death provides a strong rationale for combination approaches with immunotherapy, particularly in earlier treatment settings where immune competence is better preserved. She noted that promising Phase 1 efficacy signals observed in treatment-naive patients with high PD-L1 expression warrant further evaluation.
Detailed results from SigVie-002 will be submitted for presentation at a future medical congress. Pfizer is also exploring sigvotatug vedotin in novel combinations, including with PF'4404, a bispecific antibody targeting PD-1 and VEGF, in early-stage lung cancers and other IB6-expressing tumors.
Since acquiring Seagen, Pfizer has advanced a broad ADC portfolio spanning marketed medicines and pipeline programs, including fetrastobart vedotin, a PD-L1-directed ADC currently in Phase 3 in NSCLC, and additional IB6-targeted ADCs with alternate payloads. The company has set a goal of delivering eight potential oncology breakthroughs by 2030.
The failed readout puts pressure on Pfizer's broader ADC strategy in thoracic cancers, though the second-line signal and ongoing first-line combination trial offer a path forward. Investors will watch for detailed data at an upcoming medical congress and for updates from the Phase 3 combination study with pembrolizumab.
This article is for informational purposes only and does not constitute investment advice.
