Authors: 

Xiaotian Zhang¹, Zengqing, Guo², Jingdong, Zhang³, Weijian, Guo⁴, Meili, Sun⁵, Nong Xu⁶, Charlie Qi⁷, Xuelian, Zhu⁷, Lijuan Zhang⁷, Xueming, Qian⁷, Caroline, Germa⁸, Lin Shen¹

1. Peking University Cancer Hospital; 2. Fujian Cancer Hospital; 3. Liaoning Cancer Hospital; 4. Fudan University Shanghai Cancer Center; 5. Jinan Central Hospital; 6. Affiliated Hospital Zhejiang University; 7. Suzhou Transcenta Therapeutics Co, Ltd. 8. Transcenta Therapeutics, INC. USA

Background: 

Osemitamab (TST001) is a potential best-in-class antibody with improved claudin 18.2 (CLDN18.2) affinity and enhanced antibody-dependent cell-mediated cytotoxicity effect, leading to anti-tumor activity in CLDN18.2 positive gastric cancer animal models, including those with low to medium levels of expression. 

Animal models have demonstrated strong synergistic anti-cancer activities among osemitamab, anti-PD-1 antibodies and chemotherapies, regardless of the PD-L1 CPS levels. 

Promising efficacy of osemitamab plus CAPOX chemotherapy as first-line treatment for G/GEJ cancer has been observed in cohort C of TranStar102, which was reported previously at ASCO and ESMO-GI.

Conclusions:

The combination of osemitamab plus CAPOX and nivolumab as first-line treatment for patients with G/GEJ cancer is safe and well tolerated. The triple combination didn’t increase the safety risk compared with osemitamab combination with CAPOX. 

Preliminary efficacy data indicate that the combination of osemitamab plus CAPOX and nivolumab as the first-line treatment for patients with G/GEJ cancer had very encouraging anti-tumor activities regardless of PD-L1 expression, especially for the patients with H/M CLDN18.2 expression compared with the historical data.