China-based biotech Transcenta Holdings Ltd (HKG: 6628) has presented updated efficacy data from the expansion cohort of the TranStar102 trial at the ESMO Congress 2023 in Madrid, Spain. The trial assessed osemitamab (TST001), a high affinity humanized anti-CLDN18.2 monoclonal antibody (mAb) with enhanced antibody-dependent cellular cytotoxicity (ADCC), in combination with CAPOX chemotherapy as a first-line treatment for advanced gastric/gastroesophageal (G/GEJ) cancer.
Study Design and Patient Outcomes
Cohort C of the TranStar102 study (NCT04495296) was designed to evaluate the safety and efficacy of osemitamab plus CAPOX as a first-line treatment in advanced G/GEJ cancer. The study enrolled and treated 49 patients with 6mg/kg Q3W osemitamab and CAPOX in the efficacy expansion cohort. With a median follow-up of 11.3 months, 28 out of 42 patients with measurable lesions achieved partial response, with 23 confirmed responses (54.8%). The median duration of response (DoR) for these responders was 12.7 months.
Efficacy and Safety Profile
Among the 49 patients, 20 had progression of disease or death, resulting in an estimated median progression-free survival (PFS) of 14 months. The median overall survival (OS) was not reached due to the limited number of events. The safety profile was characterized by manageable on-target-off-tumor effects, including nausea, hypoalbuminemia, and vomiting, most of which were grade 1 or 2 and occurred during the first two cycles.
Future Exploration and Dosing
The preliminary efficacy, safety, and PK/PD data of osemitamab demonstrate excellent risk-benefit characteristics, supporting future exploration at doses of 6mg/kg Q3W or 4mg/kg Q2W. These findings underscore the potential of osemitamab in combination with CAPOX as a promising treatment option for patients with advanced G/GEJ cancer.-Fineline Info & Tech
