Cullinan Oncology, Inc. announced first monotherapy clinical data from its Phase 1 study of CLN-619 in patients with advanced solid tumors. Findings from the clinical trial will be shared at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting as a poster presentation during the “Developmental Therapeutics—Immunotherapy” session (poster # 2532) on June 3, 2023. CLN-619 is being studied in an ongoing Phase 1 clinical trial both as a monotherapy and in combination with pembrolizumab in patients with advanced solid tumors.

Summary of Key Clinical Results from Monotherapy Arm of Phase 1 Clinical Trial in Patients with Solid Tumors: Monotherapy dose escalation demonstrates acceptable safety profile of CLN-619 across all doses assessed (0.1, 0.3, 1, 3, 6, 10mg/kg): No dose-limiting toxicities were observed; Consistent with other monoclonal antibodies, infusion-related reactions were limited to the first dose and all grade 1/2 in patients receiving mandated pre-medication One CR was observed in a patient with parotid gland cancer whose cancer had progressed on prior checkpoint inhibitor therapy; Two PRs (pending confirmation) were observed in patients with endometrial cancer, one whose cancer had progressed on prior checkpoint inhibitor therapy; Stable disease was observed in patients across multiple tumor types, including cervical, ovarian, salivary gland, and breast cancers; Patients were heavily pre-treated with a median of 3 prior systemic therapies (1 – 7), and 54% had received prior immune checkpoint inhibitor therapy and The trial continues to enroll in both the monotherapy and combination arms. CLN-619 is being studied in an ongoing Phase 1 clinical trial both as a monotherapy and in combination with pembrolizumab. The study design allows dose level extensions as well as expansion in tumor-specific cohorts. Consistent with prespecified criteria and based on initial safety and efficacy observations, Cullinan will initiate monotherapy expansion cohorts in endometrial cancer and cervical cancer.

Additional expansion cohorts may be initiated based upon clinical activity observed in the current trial.