Eucure Biopharma, a subsidiary of Biocytogen, announced its anti-CTLA-4 antibody (YH001), in combination with Junshi Biosciences' anti-PD-1 monoclonal antibody, Toripalimab Injection (TUOYI?), has demonstrated encouraging anti-tumor activity in a dose-escalation Phase I clinical trial in Australia. The study was designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary efficacy of YH001 therapy in combination with Toripalimab in patients with solid tumors.

A 64-year-old male with a gastroesophageal junction tumor and liver/lung metastases who failed three prior lines of chemotherapy was enrolled in the 0.3 mg/kg dose cohort on September 17, 2020. The subject received one cycle (21 days) of YH001 monotherapy, followed by combination therapy with 240 mg Toripalimab for 7 cycles (21 weeks). Imaging assessments at 8 weeks post study treatment indicated stable disease with a 12.7% reduction in the summary of diameter of all target lesions relative to baseline. At 15 weeks post study treatment, imaging assessments indicated a partial response, with a 60.9% reduction in the summary of diameter of all target lesions relative to baseline. No dose-limiting toxicity events were observed, and only a Grade 1 adverse event (fatigue) was reported.

"We are very pleased to see patients experiencing partial remission of tumor target lesions in this clinical study, which is progressing smoothly in Australia," said Dr. Yuelei Shen, Chairman of Biocytogen and CEO of Eucure Biopharma. Dr. Shen added that a YH001 trial in China will commence "as soon as possible, so as to bring effective and innovative products to Chinese patients."

YH001 is an anti-cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) humanized monoclonal antibody that blocks the interaction between CTLA4 and CD80/CD86. YH001 can trigger antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) to remove CTLA-4 expressing cells, especially regulatory T cells, to enhance T-cell-mediated antitumor responses. Preclinical data indicates that YH001 outperforms Ipilimumab (a currently approved CTLA-4 drug) in CTLA-4 binding affinity and inducing ADCC activity.