Pacylex and Heidelberg Pharma Demonstrate Zelenirstat's Potential as Novel ADC Payload

Pacylex Pharmaceuticals Inc. and Heidelberg Pharma AG presented collaborative research demonstrating zelenirstat's effectiveness as a payload in antibody drug conjugates at the 16th Annual World ADC conference in San Diego. The data revealed that zelenirstat ADCs showed 20-fold to more than 1,000-fold higher potency against cancer cell lines compared to zelenirstat alone, representing a significant advancement in ADC technology development. The research addressed the critical need for new ADC payloads, as only a limited number have entered clinical practice despite the growing importance of ADC therapies in oncology.

Zelenirstat, a first-in-class N-myristoyltransferase inhibitor currently in clinical development, demonstrated an acceptable safety profile in Phase 1 studies involving patients with refractory/relapsed lymphoma and solid tumors. The compound's unique mechanism of action targets multiple processes essential to cancer cell growth and survival, making it particularly suitable for ADC applications. Dr. Michael Weickert, CEO of Pacylex, emphasized the significance of these findings, noting that deploying zelenirstat as an ADC payload markedly improves its potency against solid tumor cells while leveraging its established clinical safety profile.

The presented research evaluated multiple breast and prostate cancer cell lines using different ADC targeting molecules and linkers, showcasing the versatility of zelenirstat as a payload candidate. Pacylex's family of NMT inhibitors includes 28 compounds with single-digit nM IC50s against human NMT1, all potentially suitable for ADC development. The company plans to aggressively explore zelenirstat and other Pacylex molecules as targeted ADC payloads, building on the positive results presented at the conference. Additional information about Pacylex's research and development programs can be found at https://www.pacylex.com, while details about Heidelberg Pharma's ADC technologies are available at https://www.heidelberg-pharma.com.

The collaboration between these two clinical-stage companies represents an important step in advancing ADC technology, particularly given the limited number of effective payloads currently available. Zelenirstat's dual utility as both an oral therapy for hematologic cancers and as a potent ADC payload for solid tumors positions it as a versatile therapeutic candidate. The FDA has previously granted zelenirstat both Orphan Drug Designation and Fast Track Designation for AML, further validating its potential clinical significance. The ongoing clinical investigation in relapsed/refractory AML patients continues to accrue participants, with study details available through ClinicalTrials.gov.