Pfizer's Lung Cancer Drug Sigvotatug Vedotin Misses Primary Endpoint in Phase 3 Trial
Alina Collins
Pfizer's ADC drug sigvotatug vedotin failed to beat chemotherapy on overall survival in a late-stage lung cancer trial, but a subgroup of first-line-only patients showed a stronger signal — the upcoming Keytruda combo trial will now decide the program's fate.
What exactly went wrong in this trial?
Sigvotatug vedotin — an antibody-drug conjugate that straps a chemo warhead onto an antibody to deliver it directly into tumor cells — failed to significantly extend overall survival versus docetaxel across the full patient population.
This means → under the current trial design, Pfizer does not have the data to file for regulatory approval. The path to a standalone label is blocked.
The trial enrolled patients with locally advanced, unresectable, or metastatic non-squamous non-small cell lung cancer who had already received at least one prior line of systemic therapy.
Why hasn't Pfizer abandoned the program?
Pfizer disclosed a subgroup analysis: among patients who had received only one prior line of therapy, the drug showed a stronger improvement trend in both overall survival and progression-free survival.
In plain terms = the drug worked notably better in patients whose bodies were less beaten up by prior treatment.
Pfizer said this bolsters its confidence in the program — but subgroup data is a signal, not proof. It still needs validation in a separate, dedicated trial.
What is the next decision point?
Pfizer is advancing a late-stage trial combining sigvotatug vedotin with Merck's Keytruda — a PD-1 immune checkpoint inhibitor and currently the world's top-selling cancer drug.
This means → Pfizer's bet is that the monotherapy isn't strong enough alone, but an ADC + immunotherapy combo might break through.
This reflects a broader strategic pivot in Pfizer's oncology pipeline — from single-agent gambles to combination plays. Whether the subgroup signal holds up in the combo trial will determine this program's commercial value.
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