Authors:

Jifang Gong¹, Dan Liu¹, Zengqing Guo², Jingdong Zhang³, Weijian Guo⁴, Meili Sun⁵, Nong Xu⁶, Chuan Qi⁷, Lijuan Zhang⁷, Zhenzhong Xia⁷, Jianming Wang⁸, Li Xu⁸, 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 is a humanized monoclonal antibody with improved affinity to CLDN18.2，reduced fucosylation and enhanced antibody-dependent cell-mediated cytotoxicity activity and has been observed to upregulate PD-L1 expression on CLDN18.2-positive tumor cells. 

In vivo anti-tumor activity of combination of osemitamab plus an anti-PD-1/PD-L1 antibody and chemotherapies was significantly stronger than any of the doublet combinations, regardless of the PD-L1 CPS levels, making the triple combination of osemitamab, nivolumab and CAPOX an attractive combination to explore. 

Promising efficacy of osemitamab plus CAPOX and nivolumab as first-line treatment for G/GEJ cancer has been observed and reported previously at ESMO. Here we report the updated results including overall survival.

Conclusions:

The updated data indicate that the combination of TST001 plus nivolumab and CAPOX for first-line treatment of patients with G/GEJ cancer is safe and well tolerated. 

Preliminary efficacy data indicate that the combination of osemitamab plus CAPOX and nivolumab as first-line treatment for patients with G/GEJ cancer had very encouraging durable PFS and overall survival regardless of PD-L1 expression, especially for the patients with CLDN18.2 (≥40%, ≥2+) expression compared with the historical data of existing or emerging therapies.