Hanmi Pharmaceutical Confirms Antitumor Activity of Next-Generation Dual Inhibitor Anticancer Drug

Phase 1 Clinical Trial Results Presented at the European Society for Medical Oncology

Hanmi Pharmaceutical has reported positive results in global clinical development by confirming the initial safety profile and antitumor activity of its next-generation targeted anticancer innovative drug, the “EZH1/2 dual inhibitor (HM97662),” in a Phase 1 clinical trial.

Professor Beomseok Kim of the Department of Hematology and Oncology at Seoul National University Hospital (left) and Senior Researcher Dongjun Lee of the ONCO Clinical Team at Hanmi Pharmaceutical (right) are explaining the Phase 1 clinical study results of HM97662 at the European Society for Medical Oncology (ESMO Congress 2025) held in Berlin, Germany, on the 17th. Hanmi Pharmaceutical

Hanmi Pharmaceutical announced on the 22nd that it participated in the European Society for Medical Oncology (ESMO Congress 2025), held in Berlin, Germany, from October 17 to 21, and presented the results of its Phase 1 clinical study on HM97662 in a poster session.

HM97662 is being developed as a next-generation innovative targeted therapy with a “dual inhibition mechanism” that simultaneously blocks both EZH1 and EZH2 proteins, offering superior anticancer efficacy and the potential to overcome resistance compared to existing EZH2-selective inhibitors.

EZH1 and EZH2 proteins, known as “genetic regulatory switches,” are key factors in regulating cancer cell growth and differentiation. By controlling both proteins at the same time, it is possible to more effectively block the function of the “Polycomb Repressive Complex 2 (PRC2),” thereby enhancing the suppression of cancer cell growth.

In fact, when only EZH2 is selectively inhibited, EZH1 may become complementarily activated, potentially contributing to drug resistance. As a result, the dual inhibition approach targeting both EZH2 and EZH1 is gaining attention as a more promising therapeutic strategy.

At the congress, Hanmi Pharmaceutical presented the results of its Phase 1 clinical trial, which evaluated the safety, tolerability, and pharmacokinetic characteristics of HM97662 in patients with advanced or metastatic solid tumors. Initial antitumor activity was observed in some patients. A total of 28 patients participated in the Phase 1 trial, receiving once-daily doses across seven dose groups ranging from 50 to 350 mg. Most patients had undergone four or more lines of standard therapy and belonged to high-risk groups with limited alternative treatment options.

HM97662 demonstrated a manageable safety profile without severe toxicity leading to treatment discontinuation or death. Some patients experienced “partial response (PR)” and “long-term stable disease (SD).”

Cases confirming antitumor activity included a patient with SMARCA4-deficient uterine sarcoma (300 mg dose), who achieved a partial response (-39%) according to RECIST v1.1 criteria, and an ovarian cancer patient (200 mg dose), who maintained stable disease for over 15 months and experienced up to a 26% reduction in tumor size.

Kim Beomseok, Professor of Hematology and Oncology at Seoul National University Hospital and lead investigator for the Phase 1 study of HM97662, stated, “It is noteworthy that positive antitumor effects were observed in patients with advanced or metastatic solid tumors, with some patients achieving partial responses and maintaining long-term stable disease while continuing anticancer treatment. We hope that subsequent clinical studies will establish HM97662 as an effective treatment option for various types of cancer.”

Hanmi Pharmaceutical also plans to gradually establish clinical evidence by designing tailored combination therapy strategies that reflect the biological characteristics and molecular mutation profiles of each cancer type. Noh Youngsoo, Director of the ONCO Clinical Team at Hanmi Pharmaceutical, commented, “The results of the Phase 1 study of HM97662 are significant in that they suggest the EZH1/2 dual inhibition strategy, which has been validated in preclinical research, can also demonstrate antitumor activity in actual clinical treatment. We expect to expand indications to various cancer types in the future and present a new paradigm in anticancer therapy.”