52% ORR per mIWG criteria, including 83% ORR for patients receiving 100 mg BID
88% ORR per PPR criteria, including 100% ORR for patients receiving 100 mg BID
Median time to response 2.2 months with median duration of response and median PFS not yet reached
Top-line data from APEX Part 2 on-track for mid-2025
Cogent to host investor webcast on Monday, December 9 at 8:00 a.m. ET
Dec. 08, 2024 -- Cogent Biosciences, Inc. (Nasdaq: COGT), a biotechnology company focused on developing precision therapies for genetically defined diseases, today reported positive updated data from Part 1 of the Company’s ongoing Phase 2 APEX clinical trial evaluating bezuclastinib in patients with advanced systemic mastocytosis (AdvSM) at the 66th American Society of Hematology (ASH 2024) Annual Meeting & Exposition taking place December 7-10, 2024 in San Diego, CA.
“Bezuclastinib has the potential to transform the treatment landscape for people living with advanced systemic mastocytosis,” said Daniel J. DeAngelo, M.D., Ph.D., Chief of the Division of Leukemia at the Dana-Farber Cancer Institute and Professor of Medicine, Harvard Medical School. “The impressive clinical data presented today from APEX Part 1 demonstrates a combination of rapid and deep clinical responses, with a safety profile that avoids several of the most concerning side effects for AdvSM patients today.”
“We are excited to share today the updated clinical data from APEX Part 1 studying bezuclastinib in patients with advanced systemic mastocytosis,” said Andrew Robbins, Cogent’s President and Chief Executive Officer. “These results show the enormous promise that a highly potent, highly selective, non-brain penetrant KIT inhibitor may provide to this patient population. We look forward to completing enrollment in APEX Part 2 and sharing the results from that study in mid-2025.”
APEX is a global, open-label, multi-center, two-part Phase 2 clinical trial in patients with AdvSM evaluating the safety, efficacy, pharmacokinetic, and pharmacodynamic profiles of bezuclastinib. Thirty-two patients were treated in Part 1 at one of four dose levels (50 mg BID, 100 mg BID, 200 mg BID or 400 mg QD). Earlier this year, Cogent announced APEX Part 2 would be conducted at the optimized 150mg QD dose, which closely matches the exposure from 100 mg BID dose in APEX Part 1. The median age of patients at study entry was 68 years (ranging from 33-87 years). Patients were enrolled with the following sub-types: seven patients with aggressive systemic mastocytosis (ASM), 23 patients with systemic mastocytosis with associated hematologic neoplasm (SM-AHN), and two patients with mast cell leukemia (MCL). Five patients had received prior avapritinib and 10 patients had received prior midostaurin treatment.
As of the data cutoff date of October 11, 2024, 32 patients enrolled were evaluated for signs of clinical activity, 27 of whom were mIWG-MRT-ECNM evaluable. Clinical activity analyzed across dose levels and focused on 100 mg BID cohort showed:
52% ORR (CR+CRh+PR+CI) per mIWG-MRT-ECNM criteria, including 61% ORR for TKI-treatment-naïve patients
83% ORR for patients treated at 100 mg BID dose cohort
88% ORR (CR+PR) per pure pathological response (PPR) criteria
100% ORR for patients treated at 100 mg BID dose cohort
Median time to achieve response was 2.2 months and median duration of response has not yet been reached
Median PFS was not yet reached at median follow-up of 20 months; PFS rate at 24 months was 82%
Nearly all patients demonstrated a significant improvement in biomarkers associated with disease burden. Patients without post baseline biomarker data were excluded from relevant analyses.
94% of patients achieved ≥50% reduction in serum tryptase levels
100% of patients receiving ≥2 cycles achieved ≥50% reduction
66% of patients achieved reduction of serum tryptase below 20 ng/mL
93% of KITD816V-positive patients achieved ≥50% reduction in KIT D816V variant allele fraction (VAF)
100% of evaluable patients achieved a ≥50% reduction in bone marrow mast cell burden
83% achieved complete clearance of mast cell aggregates by central review
Cogent is actively enrolling patients into APEX Part 2 which is anticipated to complete enrollment in Q1 2025 with top-line results expected in mid-2025.
Cogent will present 24-week follow-up data from patients who participated in the Open Label Extension portion of the ongoing SUMMIT trial on Monday, December 9, 2024 at ASH. SUMMIT is a randomized, double-blind, placebo-controlled, global, multicenter Phase 2 trial evaluating bezuclastinib in patients with Nonadvanced Systemic Mastocytosis (NonAdvSM).
Cogent Biosciences is a biotechnology company focused on developing precision therapies for genetically defined diseases. The most advanced clinical program, bezuclastinib, is a selective tyrosine kinase inhibitor that is designed to potently inhibit the KIT D816V mutation as well as other mutations in KIT exon 17. KIT D816V is responsible for driving systemic mastocytosis, a serious disease caused by unchecked proliferation of mast cells. Exon 17 mutations are also found in patients with advanced gastrointestinal stromal tumors (GIST), a type of cancer with strong dependence on oncogenic KIT signaling. In addition to bezuclastinib, the Cogent Research Team is developing a portfolio of novel targeted therapies to help patients fighting serious, genetically driven diseases initially targeting mutations in FGFR2, ErbB2, PI3Kα and KRAS. Cogent Biosciences is based in Waltham, MA and Boulder, CO. Visit our website for more information at www.cogentbio.com. Follow Cogent Biosciences on social media: X (formerly known as Twitter) and LinkedIn. Information that may be important to investors will be routinely posted on our website and X.
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