On May 30, 2026 Cogent Biosciences, Inc. (Nasdaq: COGT), a biotechnology company focused on developing precision therapies for genetically defined diseases, reported detailed clinical data from the primary analysis of the PEAK Phase 3 trial of bezuclastinib in combination with sunitinib in patients with Gastrointestinal Stromal Tumors (GIST) who have received prior treatment with imatinib.

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The presentation titled Primary Results of the Phase 3 Peak Study of Bezuclastinib + Sunitinib vs Sunitinib Monotherapy in Advanced Gastrointestinal Stromal Tumors (GIST) ​will be presented by Andrew Wagner, M.D., Ph.D., Senior Physician, Center for Sarcoma and Bone Oncology, Dana-Farber Cancer Institute, and Associate Professor of Medicine, Harvard Medical School at the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) annual meeting and will be available on the Cogent website at View Source

"We are thrilled with the results from the PEAK Phase 3 trial demonstrating a statistically significant and clinically meaningful improvement in progression-free survival and objective response rate with bezuclastinib in combination with sunitinib compared to sunitinib alone," said Andrew Robbins, President and Chief Executive Officer of Cogent Biosciences. "Importantly, there was a clear benefit across all mutational patient subgroups, coupled with a safety profile generally consistent with the known profile of single agent sunitinib. Building on our announcement that the bezuclastinib combination was granted FDA Priority Review earlier this week, we plan to launch bezuclastinib later this year and are well prepared to ensure bezuclastinib combination access for GIST patients in need."

"The results presented today clearly demonstrate that the combination of bezuclastinib and sunitinib provides impressive clinical activity for patients with KIT-driven gastrointestinal stromal tumors," said Andrew Wagner, M.D., Ph.D., Senior Physician, Center for Sarcoma and Bone Oncology, Dana-Farber Cancer Institute, and Associate Professor of Medicine, Harvard Medical School. "I am very excited about the potential for this combination and expect it will be rapidly adopted as the new standard of care for patients with second-line GIST."

PEAK Phase 3 Trial Results

As reported in November 2025, PEAK is a global, randomized Phase 3 clinical trial evaluating bezuclastinib in combination with sunitinib vs. sunitinib monotherapy in patients with imatinib-resistant or intolerant GIST. As of the cutoff date, September 30, 2025, the bezuclastinib combination demonstrated a substantial and highly statistically significant clinical benefit on the primary endpoint of PFS, reducing risk of disease progression or death compared to the current standard of care by 50% (hazard ratio of 0.50, 95% CI: 0.39 – 0.65). mPFS, as assessed by blinded independent central review, was 16.5 months for the bezuclastinib combination vs. 9.2 months for sunitinib monotherapy. Additionally, the bezuclastinib combination demonstrated an unprecedented ORR in imatinib-resistant patients, with 46% of patients treated with the bezuclastinib combination achieving an objective response compared to 26% of patients treated with sunitinib. Data for overall survival remains immature.

Based on the ongoing patients receiving treatment on the bezuclastinib arm as of March 31, 2026, the mean duration of treatment for the bezuclastinib combination is now estimated to be 21.4 months.

Results of Genotype Subgroup Analysis

Using all genotyping information available at baseline, a comparative analysis of PFS was performed across several patient subgroups based on their primary and secondary KIT mutation status. Across all subgroups, the bezuclastinib combination demonstrated a clear advantage over sunitinib monotherapy.

Cogent_Genotype Subgroup

PFS2 Results

Additional data presented today demonstrate impressive benefit for patients receiving the bezuclastinib combination when measuring PFS2, defined as the time from randomization to progression on the next line of therapy or death. Median PFS2 was not reached versus 21 months (HR=0.57, 95% CI: 0.41-0.78) for patients initially treated with the bezuclastinib combination compared with sunitinib monotherapy. This finding reinforces the durability of clinical benefit for patients receiving the bezuclastinib combination.

Safety Data

As of the data cutoff, the bezuclastinib combination was generally well tolerated, and no unique risks were observed with the novel combination when compared to the known safety profile of sunitinib. The most commonly reported Grade 3+ treatment emergent adverse events in either arm (bezuclastinib combination vs. sunitinib) included: Hypertension (29.4% vs. 27.4%), Neutropenia (15.2% vs. 15.4%), ALT/AST increased (10.8% vs. 1.4%), Anemia (9.3% vs. 4.8%) and Diarrhea (7.8% vs. 7.2%). 7.4% of patients on the bezuclastinib combination and 3.8% of patients on sunitinib monotherapy discontinued study treatment(s) due to treatment related adverse events. Hepatic adverse events were predominantly transient and manageable lab abnormalities; the majority of which were asymptomatic, low grade, non-serious and reversible. In the combination arm, ALT/AST elevations led to bezuclastinib dose reductions in 12.7% of patients with only 3 subjects (1.5%) discontinuing bezuclastinib for ALT/AST elevations. All Grade 3 ALT/AST elevations resolved, and no Grade 4 elevations were reported.

Bezuclastinib Combination in Exon 9 First Line GIST Patients

Cogent also announced today the initiation of a single-arm, 40 patient extension cohort of the PEAK trial investigating the safety and efficacy of the bezuclastinib combination in first-line GIST patients with KIT exon 9 primary mutations who have received limited or no imatinib treatment. This cohort is designed to prospectively measure ORR and PFS in this patient population, building upon the 25.1 mPFS reported in a subgroup of 32 patients with detectable exon 9 mutations treated with the bezuclastinib combination in the Phase 3 PEAK trial.

Bezuclastinib – Expanded Access Program

Working with the FDA, Cogent has established active Expanded Access Programs (EAPs) for U.S. patients with GIST or SM who meet disease-specific criteria and could benefit from treatment with bezuclastinib or the combination of bezuclastinib and sunitinib. For more information please visit: View Source

(Press release, Cogent Biosciences, MAY 30, 2026, View Source [SID1234666243])