HiberCell Announces Successful Completion of Dose Escalation and Enrollment Update for Ph1b Study Evaluating HC-7366 in Combination with WELIREG® (belzutifan) in Advanced ccRCC

BOSTON, May 27, 2025 (GLOBE NEWSWIRE) — HiberCell, Inc., a clinical-stage biotechnology company developing therapeutics to address cancer relapse, metastasis, and resistance, today announced the successful completion of the dose escalation portion of its Phase 1b study evaluating HC-7366—an activator of the integrated stress response (ISR) kinase GCN2—in combination with Merck’s (known as MSD outside the US and Canada) oral hypoxia-inducible factor-2 alpha (HIF-2α) inhibitor, WELIREG^® (belzutifan) for the treatment of advanced clear cell renal cell carcinoma (ccRCC).

The dose escalation phase enrolled 18 patients and was designed to evaluate the safety, tolerability, and pharmacokinetics (PK) of HC-7366 and to identify the recommended doses for expansion. Three dose levels of HC-7366 (20 mg, 40 mg, 60 mg) were assessed in combination with fixed-dose belzutifan (120 mg orally, once daily). All three dose levels tested cleared the respective dose-limiting toxicity (DLT) evaluations. Based on the favorable safety and PK/PD profile, the 40 mg and 60 mg doses of HC-7366 were selected for further evaluation in combination with belzutifan.

HiberCell also announced that enrollment in the 40 mg expansion cohort is now complete. Enrollment for the 60 mg cohort is ongoing and is expected to complete before the end of the second quarter of 2025. Each expansion cohort is designed to enroll 15 patients. In parallel, a separate cohort evaluating HC-7366 as monotherapy at the 60 mg dose is also actively enrolling patients.

“We’re pleased to announce the successful completion of the dose escalation phase of our trial, a key milestone in establishing the safety of combining HC-7366 with belzutifan,” said Steven Gillis, Ph.D., Chairman and Acting CEO of HiberCell. “We’re encouraged by the strong pace of enrollment and we’re grateful to the clinical sites, investigators, and patients participating in the study. We look forward to assessing additional safety, PK/PD, and preliminary efficacy data from the expansion cohorts, particularly as the 40 mg and 60 mg doses have been identified as the most likely to demonstrate efficacy based on preclinical models.”

HiberCell is continuing to advance its understanding of HC-7366’s mechanism of action and recently presented a poster at the American Association for Cancer Research (AACR) Annual Meeting titled “In Vivo Tumor Growth Control by General Control Nonderepressible 2 (GCN2) Targeting Agents Results from Kinase Activation,” highlighting that activation of the GCN2 pathway is associated with enhanced anti-tumor activity across multiple preclinical models.

WELIREG^® is a registered trademark of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.

About HC-7366

HC-7366 is a first-in-class, first-in-human, selective, potent, small molecule activator of the general control nonderepressible 2 (GCN2) kinase. GCN2 is one of the kinases of the integrated stress response (ISR) family, which responds to amino acid deprivation and is a key metabolic stress sensor in cells. While cancer cells utilize the ISR for survival, prolonged or hyperactivation of GCN2 with HC-7366 has been shown to have antitumor and immunomodulatory activity as a monotherapy and in combination with SOC agents in preclinical models of both solid and liquid tumors. HC-7366 is currently under clinical development in a Phase 1b study in clear cell renal cell carcinoma in combination with belzutifan.

About HiberCell

HiberCell is a clinical stage oncology company, dedicated to the advancement of first-in-class agents with the novel MOA of modulation of adaptive stress pathways. We believe that therapeutic modulation of these mechanisms allows us to address tumor metastasis, treatment resistance, and cancer relapse; all significant drivers of cancer-related deaths. Our GCN2 activator, HC-7366, is currently under investigation in two Phase 1b trials in renal cell carcinoma (RCC) and acute myeloid leukemia (AML). Meanwhile, our PERK inhibitor, HC-5404 is advancing into Phase 1b development. For more information about HiberCell, please visit hibercell.com.

For Media/Investor Inquiries:

IR@hibercell.com