On April 18, 2024 Pacylex Pharmaceuticals Inc. (Pacylex) is a clinical-stage pharmaceutical company focused on the development of a new class of targeted therapies, N-myristoyltransferase inhibitors (NMTi) for the treatment of hematologic and solid tumor cancers, reported that the first patient has been dosed in a Phase 2a expansion study in patients with refractory metastatic colorectal cancer (Press release, Pacylex Pharmaceuticals, APR 18, 2024, View Source [SID1234645052]).

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The Phase 1 dose escalation safety and tolerability study was conducted in 29 heavily pre-treated solid tumor and lymphoma patients who averaged 4 lines of prior drug therapy on which they relapsed or were refractory. Eight colorectal cancer patients were among those included in the study. The most common treatment related adverse events identified in the trial were mild to moderate gastrointestinal side effects which were self-limiting and occurred in a minority of patients. A recommended Phase 2 dose (RP2D) for expansion studies was established. Zelenirstat prolonged progression free and overall survival in Phase 1 solid tumor patients receiving the RP2D, compared to those receiving lower doses. Prolonged Stable Disease of 6 months or longer was observed in 57% (4/7) of the patients receiving RP2D, including a patient with metastatic colorectal cancer continuing on treatment for more than 1 year with reductions of approximately 50% in CEA (carcinoembryonic antigen) and tumor volumes.

"Given the patient benefits and excellent tolerability seen in our Phase 1 study, and particularly in our sentinel colorectal cancer patient, we are eager to see if other colorectal cancer patients receiving our Phase 2 dose will also benefit," said Dr. John Mackey, CMO of Pacylex. "People with refractory colorectal cancer desperately need new treatment options, and we are investigating whether zelenirstat can provide that."

"Adding colorectal cancer as our first solid tumor indication explores the broad potential for zelenirstat, a first-in-class oral cancer therapy, in both hematologic cancers and solid tumors," said Pacylex CEO Dr. Michael Weickert. "The importance of myristoylation to many cancer processes is underappreciated, and Pacylex is way ahead in developing this novel therapeutic class, NMT inhibitors, to treat cancer refractory to available treatments."

The Company has an ongoing Phase 2a study of patients with B-cell non-Hodgkin lymphoma. This colorectal cancer Phase 2a expansion study will enroll up to 20 subjects to assess the preliminary clinical activity and confirm the safety of zelenirstat in refractory colorectal cancer.