Hanmi Pharmaceutical confirmed the potential for successful new drug development in a clinical trial administering the oral immuno-oncology drug Tibumeshirnon in conjunction with the immune checkpoint inhibitor Keytruda from the American pharmaceutical company Merck (MSD).
On the 17th, Hanmi Pharmaceutical presented the phase 2 trial stage 1 results of Tibumeshirnon at a poster session during the 2025 American Society of Clinical Oncology Gastrointestinal Cancers Symposium held in San Francisco at the end of January. Tibumeshirnon is an oral immuno-oncology substance introduced by Hanmi Pharmaceutical from RAPT Therapeutics in 2019, which blocks the 'CCR4 receptor protein' that induces the movement of regulatory T cells (immune cells) that suppress the immune response into tumors.
The company expects to reduce immune suppression signals in the tumor microenvironment and enhance immune system activity, leading to anti-tumor effects.
This clinical trial is a phase 2 trial conducted in collaboration with the American pharmaceutical companies RAPT and Merck (MSD). In initial findings from administering Tibumeshirnon and Merck's immune checkpoint inhibitor Keytruda to Epstein-Barr virus (EBV)-positive gastric cancer patients, the objective response rate (ORR) confirmed a 60% rate of patients showing objective responses, including one complete response (CR) where all cancer cells were eliminated and five partial responses (PR) where the measurable tumor size was reduced to less than half of the previous size.
The median time to tumor response (mTTR) was 2.7 months. The median duration of response (mDOR) for the chemotherapy response was 17.3 months. The median progression-free survival period (mPFS), indicating the time to recurrence in cohort 2, was 10.4 months. Hanmi Pharmaceutical explained that most adverse reactions observed in the 20 trial participants were manageable.
Professor Oh Do-yeon, the principal investigator of the phase 2 trial from Seoul National University Hospital’s Department of Hematology and Oncology, said, "The combination therapy of Tibumeshirnon and Keytruda showed positive anti-tumor effects in EBV-positive gastric cancer patients, and confirming both a high objective response rate and prolonged response duration is encouraging," adding, "These clinical results represent a significant advancement proving the potential of immuno-oncology treatment targeting the CCR4 receptor."