Pfizer Inc. (PFE) shared encouraging data from its BREAKWATER cancer trial on Saturday, and the numbers tell a pretty compelling story about tumor shrinkage. The Phase 3 trial looked at whether adding Braftovi (encorafenib) and cetuximab to chemotherapy could help patients with a particularly stubborn form of advanced colorectal cancer—the kind driven by a BRAF V600E mutation.

Turns out, it can help quite a bit.

What the Numbers Show

The trial's third cohort evaluated Braftovi combined with cetuximab and FOLFIRI chemotherapy in patients who hadn't yet received treatment for their metastatic colorectal cancer. The results showed a confirmed objective response rate of 64.4% with the Braftovi combination, compared to just 39.2% for standard treatment using FOLFIRI with or without bevacizumab. That difference was both clinically meaningful and statistically significant, with an odds ratio of 2.76 and a p-value of 0.001.

For context, confirmed objective response rate means the percentage of patients whose tumors actually shrank and stayed shrunk when doctors checked again at least four weeks later. It's one thing for a tumor to respond initially, but confirmation matters.

The data were presented at the 2026 American Society of Clinical Oncology Gastrointestinal Cancers Symposium, where oncologists gather to compare notes on what's working and what isn't.

Even more interesting: the durability of these responses. Among patients receiving the Braftovi combination with cetuximab and FOLFIRI, 57.4% maintained their response for at least six months. That compares to just 34.5% for those on standard treatment with FOLFIRI, with or without Roche Holdings AG's (RHHBY) Avastin (bevacizumab).

The researchers couldn't yet estimate the median duration of response for either treatment arm, which tells you the data is still maturing. Overall survival data is being analyzed descriptively for now, and the BREAKWATER trial continues with an estimated completion date in 2027.

Regulatory Context

The FDA granted Braftovi accelerated approval in December 2024 when combined with cetuximab and a different chemotherapy backbone called mFOLFOX6 for patients with BRAF V600E-mutant metastatic colorectal cancer. That approval hinged on the drug's ability to significantly improve tumor response rates in treatment-naive patients, which was one of the study's primary endpoints.

The "accelerated" part means something specific: Pfizer still needs to prove the drug delivers actual clinical benefit to keep that approval. That's what the ongoing BREAKWATER trial is designed to confirm.

Other Pipeline News

This isn't Pfizer's only recent oncology win. Back in December 2025, the company released detailed Phase 3 results for Tukysa (tucatinib) as a first-line maintenance treatment for HER2-positive metastatic breast cancer. That trial, called HER2CLIMB-05, included patients following chemotherapy-based induction and tested Tukysa combined with trastuzumab and pertuzumab.

The primary endpoint showed a 35.9% reduction in the risk of disease progression or death for patients treated with the Tukysa combination compared to those who received placebo instead of Tukysa alongside the same antibody drugs.

Pfizer shares were down 0.26% at $25.41 on Monday at the time of publication.