Pfizer's latest attempt to tackle a tough cancer just got a mixed report card. On Monday, the pharma giant announced results from its Phase 3 SigVie-002 trial testing sigvotatug vedotin, an antibody-drug conjugate (ADC), in patients with previously treated advanced non-squamous non-small cell lung cancer (NSCLC). The drug didn't hit its primary goal of improving overall survival across the entire study population compared to the chemo drug docetaxel. But the story isn't all bad.

The trial enrolled adults with locally advanced, unresectable, or metastatic non-squamous NSCLC who had already tried at least one prior line of therapy. While the overall numbers weren't statistically significant, Pfizer noted that patients who had received only one prior line of systemic therapy — roughly two-thirds of the participants — showed a stronger trend toward better overall survival and progression-free survival. That's a glimmer of hope, but an exploratory analysis failed to find a clear link between treatment response and levels of integrin beta-6 (IB6), the protein the drug targets.

The safety profile of sigvotatug vedotin was consistent with earlier studies and considered manageable. Detailed results are expected to be presented at a future medical meeting.

Pfizer's Chief Oncology Officer, Jeff Legos, acknowledged the challenge: "Patients with previously treated advanced NSCLC are a historically difficult-to-treat population, and there is clearly more work to be done to improve the outcomes for this population."

Despite the setback, Pfizer isn't giving up on the drug. The company is already running another Phase 3 trial testing sigvotatug vedotin in combination with pembrolizumab as a first-line treatment for advanced NSCLC — essentially moving the drug to an earlier stage of the disease, where it might have a better shot. This is a common strategy in oncology: if a drug doesn't work well in heavily pretreated patients, try it earlier when patients are stronger.

Pfizer also emphasized that it's expanding its ADC pipeline, a focus since its acquisition of Seagen. The company is developing several other oncology candidates, including additional IB6-targeted therapies and other investigational ADCs. All this supports Pfizer's goal of delivering eight potential oncology breakthroughs by 2030.

As for the stock, Pfizer shares were down 0.74% at $24.89 on Tuesday. Investors seem to be taking the mixed results in stride, perhaps waiting to see what the first-line data looks like.