Item 8.01 Other Events
On June 3, 2023, Cogent Biosciences, Inc. (the “Company”) announced positive lead-in data from its ongoing Phase 3 PEAK trial evaluating the selective KIT D816V inhibitor bezuclastinib in patients with Gastrointestinal Stromal Tumors (“GIST”) and presented the data results at the American Society of Clinical Oncology Annual Meeting in Chicago, IL.
PEAK Study Design
The PEAK study is a randomized, open-label, global, Phase 3 clinical trial evaluating bezuclastinib in combination with sunitinib in GIST patients previously treated with imatinib. As of the data cutoff date of March 29, 2023, 39 patients had been treated in Part 1, with 19 patients in Part 1a and 20 patients in Part 1b. Seven patients had received only imatinib as prior therapy, and 32 patients had received at least two prior tyrosine kinase inhibitor (“TKI”) therapies.
Safety Data
As of the cutoff date of March 29, 2023, the combination of bezuclastinib and sunitinib was generally well-tolerated with an encouraging safety profile. The majority of treatment-emergent adverse events (“TEAEs”) were low-grade and reversible, with a low rate of Grade 3 or higher events observed. 23% of patients experienced dose reductions of either medication, and only two patients discontinued treatment due to adverse events. Across Part 1a and Part 1b, there were only two patients with serious adverse events reported that were possibly associated with either study medication including one patient with Grade 2 neutrophil count decrease and pyrexia and Grade 3 platelet count decrease and one patient with Grade 2 bacterial peritonitis and Grade 3 febrile neutropenia. Overall, the safety and tolerability profile of the combination appears consistent with that of single-agent sunitinib, suggesting that bezuclastinib is not adding to the overall frequency or severity of adverse events associated with single-agent sunitinib.
Clinical Activity Data
As of the cutoff date, 39 patients had been treated for at least one 28-day cycle, with a range of 1-13 cycles, and 25 of the 39 patients continue to receive treatment. Data were immature to estimate median progression free survival. Across the efficacy evaluable patients in Part 1, the disease control rate (CR + PR + durable SD) is currently 55%; including a 100% disease control rate and 17% overall response rate among the efficacy evaluable 2nd-line patients in Part 1a. Across the study, 21 patients have demonstrated radiographic evidence of reduction in target lesion diameter, including four patients who have achieved partial response. Among those responders the time to first response was as long as eight cycles, suggesting that patients currently early in treatment may achieve responses over time.
As of June 1, 2023 four of the seven second-line patients in Part 1a remained on study with at least 10 cycles of therapy.
Bezuclastinib Clinical Development
The Company is actively enrolling patients in Part 2 of the Phase 3 registration-enabling PEAK trial, which is expected to include approximately 388 second-line, post-imatinib GIST patients. Additionally, the Company remains on track to present initial clinical data from SUMMIT, a randomized, double-blind, placebo-controlled, global, multicenter, Phase 2 trial of bezuclastinib in patients with nonadvanced systemic mastocytosis in the second half of 2023. Data will include safety/tolerability, pharmacokinetics, and measures of clinical activity. The Company also expects to present clinical data from approximately 30 patients in Part 1 of the Phase 2 APEX trial in patients with advanced systemic mastocytosis at a scientific meeting in the second half of 2023.
Forward Looking Statements
This Current Report on Form 8-K contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, including, but not limited to, statements regarding the potential for bezuclastinib to bring a new standard of care to imatinib-resistant GIST patients, the anticipated size of the Company’s Phase 3 PEAK trial, the Company’s plan to present initial clinical data from SUMMIT in the second half of 2023, and the Company’s plan to present clinical data from Part 1 of the APEX trial at a scientific meeting in the second half of 2023. The use of words such as, but not limited to, “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “will,” or “would” and similar words expressions are intended to identify forward-looking statements. Forward-looking statements are neither historical facts nor assurances of future performance. Instead, they are based on the Company’s current
