Edmonton, Alberta, Canada March 17, 2025. Pacylex Pharmaceuticals Inc. (Pacylex) is a clinical-stage pharmaceutical company and world leader in developing N-myristoyltransferase inhibitors (NMTis) for cancer. Oral zelenirstat is under clinical investigation as a first-in-class targeted therapy for the treatment of hematologic cancers. Pacylex has 27 additional potent NTMis as potential payloads for antibody drug conjugates (ADCs) for the treatment of solid tumor cancers. Today, Pacylex announced the launch of a new clinical trial of oral zelenirstat in refractory/relapsed Acute Myeloid Leukemia (AML) patients and the dosing of the first patient. 

Dr. Naveen Pemmaraju is the principal investigator for the AML clinical study at The University of Texas MD Anderson Cancer Center. It will enroll AML patients whose disease has progressed or relapsed after other treatments. The clinical study is supported in part by a grant from the US Department of Defense (DOD) awarded to MD Anderson. Pacylex recently published several mechanisms by which zelenirstat efficiently kills AML cancer cells including cancer stem cells, in vitro and in vivo, supporting the launch of the clinical study. “Because preclinical results suggest AML cells are particularly sensitive to zelenirstat, we are eager to see it tested in people with AML”, said Dr. John Mackey, CMO of Pacylex. “Our Phase 1 dose escalation safety and tolerability study in solid tumor and lymphoma patients showed excellent safety and signs of efficacy even though these patients were less likely to respond to zelenirstat than those with AML.” 

A published Phase 1 dose escalation safety and tolerability study in 29 heavily pre-treated (median of 4 prior lines of drug therapy) solid tumor and lymphoma patients showed self-limited adverse events in a minority of patients without dose limiting toxicities below a daily dose of 280mg. Zelenirstat prolonged progression free and overall survival Phase 1 solid tumor patients receiving the recommended Phase 2 dose (210mg), compared to those receiving lower doses. 

Details of the new AML study are on ClinicalTrials.gov, ID NCT06613217.

For more information:

Pacylex Pharmaceuticals Contact: Michael J. WeickertCEO, Pacylex Pharmaceuticals, Inc.E: michael.weickert@pacylex.comP: 650-218-1840Twitter @Pacylex (https://twitter.com/pacylex) LinkedIn (www.linkedin.com/company/pacylex-pharma)Facebook (https://www.facebook.com/pacylex)

About zelenirstat (aka PCLX-001 or DDD86481)

Zelenirstat (formerly identified as PCLX-001 or DDD86481) is a first-in-class, oral, small-molecule NMTi being developed to treat patients with leukemia, lymphoma, and for the treatment of solid tumors when used as a payload for ADCs. Zelenirstat selectively kills cancer cells in vitro and has been shown to regress hematologic malignancies and inhibit the growth of lung and breast cancer tumors in animal models. 

Pacylex completed and published a Phase 1 multiple ascending dose safety, tolerability, and pharmacokinetics study on zelenirstat in patients with relapsed/refractory lymphoma and refractory solid tumors (NCT04836195). Zelenirstat demonstrated an acceptable safety and tolerability profile, pharmacokinetics consistent with once-daily oral dosing, and early signs of efficacy. A clinical study in relapsed/refractory AML patients is now underway (ClinicalTrials.gov ID NCT06613217).

About Pacylex Pharmaceuticals

Pacylex is the world leader in developing N-myristoyltransferase inhibitors (NMTis) as targeted therapies for the treatment of hematologic cancers and as payloads for antibody drug conjugates (ADCs) for solid tumors. Pacylex is conducting clinical studies of its lead drug, oral Zelenirstat, the first and only clinically validated NMTi. The FDA has granted zelenirstat both Orphan Drug Designation and Fast Track Designation for AML. The US Department of Defense is supporting the initial clinical investigation of zelenirstat in AML patients. Pacylex is headquartered in Edmonton, Alberta, Canada, but also has an office in the San Francisco Bay area. The Cure Cancer Foundation, Alberta Cancer Foundation, and Alberta Innovates supported the initial clinical studies. For additional information, please visit www.pacylex.com.

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