Edmonton, Alberta, Canada May 5, 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 a proprietary, potent, NMTi under clinical investigation as a first-in-class targeted therapy for the treatment of hematologic cancers. Pacylex has 27 additional potent NMTis as potential payloads for antibody drug conjugates (ADCs) for the treatment of solid tumor cancers. Today, Pacylex announced that their CEO, Michael Weickert, will present a session at the 2nd Annual ADC Payload Summit, which will be held from May 6-8, 2025, in Boston, Massachusetts, USA. The session, entitled “How Clinical Signals From Oral Zelenirstat Apply to NMT Inhibitors as ADC Payloads: Leveraging Validated Mechanisms and a Known Safety Profile” will be presented May 8 at 11:15 EST.

Despite a long history of ADC development and commercial use, only a very limited number of ADC payloads have been used to kill cancer cells. NMT inhibitors simultaneously affect multiple processes critical to cancer cell growth and survival and have been shown to regress solid tumor cancers in animal models when used as the payload for ADCs. Pacylex has exclusive license to 503 NMTis, 28 of which have single-digit nM IC50s against human NMT1. One of these, zelenirstat, is the first-in-class myristoylation inhibitor in clinical studies. It inhibits myristoylation required for assembly, translocation, and/or function of validated targets, such as B-cell receptor, Flt3-cKit complex, EGFR, and VEGFR. Zelenirstat also blocks respiratory Complex I formation in the newly formed mitochondria of cancer cells, thereby shutting down oxidative phosphorylation, which is critical for metastasis and cancer stem cells. 

Zelenirstat was well tolerated in Phase 1 patients with refractory/relapsed lymphoma and refractory solid tumors. Phase 1 safety, PK, and drug exposure results with oral zelenirstat in 24 heavily pretreated NHL and solid tumor patients receiving the recommended Phase 2 dose (RP2D) or less showed no dose-limiting toxicities. Patients receiving the RP2D had significantly better progression-free and overall survival than those treated at lower doses; 57% had stable disease or better for 6-16 months, despite cancers originating in different organ systems. A Phase 2a patient with DLBCL achieved a partial response and partial metabolic response on zelenirstat. Acute myeloid leukemia patients are currently being dosed with oral zelenirstat in another study.

“As we continue to collect evidence that the mechanisms by which NMTis kill cancer cells work in many different cancer cell types, we are more convinced than ever that they have a place as payloads in ADC development for many cancers”, said Dr. Michael Weickert, CEO of Pacylex. “The correlation between genes predicting sensitivity to our lead drug zelenirstat and the ADC targets and ADC sensitivity genes is outstanding suggesting NMTis are likely to kill cells that ADCs target. We want to work with partners to explore our large and diverse collection of NMTis as novel and effective payloads for ADC programs.”

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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