Theseus Pharmaceuticals Terminates Development Of THE-630

(RTTNews) - Theseus Pharmaceuticals, Inc. (THRX), a clinical-stage biopharmaceutical company, Thursday announced that it is discontinuing enrollment in the ongoing phase 1/2 study and terminating the development of THE-630 in patients with gastrointestinal stromal tumors (GIST).

The decision was based on two dose-limiting toxicities related to hand-foot skin reactions observed in the study.

Theseus previously released initial dose escalation data from the ongoing phase 1/2 trial, which employs a standard 3 + 3 dose escalation design, on May 25, 2023.

As of the April 21, 2023 data cutoff date, 23 patients had been dosed through Cohort 6 (18 mg) and 2 patients had been enrolled in Cohort 7 (27 mg). As of May 25, those 2 patients in Cohort 7 had cleared the dose-limiting toxicity (DLT) observation period without experiencing a DLT.

Following the data release on May 25, the third patient enrolled in Cohort 7 experienced grade 3 hand-foot skin reaction (HFSR), which required an expansion of the cohort to 6 patients. Subsequently, one of the patients enrolled in the Cohort 7 expansion group experienced grade 2 HFSR, which required a dose interruption of =7 days.