Authors:

Linlin Mao¹ , Wei Yi ¹ , Xu Alan Lin ¹ , Ying Gu ² , Zhenzhong Xia ¹ , Chuan Qi ¹ , Steven Yu ¹ , Caroline Germa ² , Xueming Qian ¹

¹Suzhou Transcenta Therapeutics Co., Limited, Suzhou, China;

² Transcenta Therapeutics Inc., Princeton, USA.

Background:

Claudin18.2(CLDN18.2),a tight junction protein highly specific to gastric mucosa, is a promising target for gastric cancer treatment[1]. Immunotherapy targeting PD-1 combined with chemotherapy has been approved as the first line treatment of gastric/gastroesophageal junction (G/GEJ) adenocarcinoma[2]. Understanding the expression profiles of CLDN18.2 and PD-L1 could offer guidance for the development of combination therapies that maximize the benefits of both agents. This study investigated the prevalence of CLDN18.2 expression from surgical resections of G/GEJ adenocarcinoma at diagnosis and its correlation with PD-L1 expression in Chinese patients.

Conclusions:

We have set up CLDN18.2 IHC assay using an in house anti CLDN18.2 antibody (Clone14G11) on the Leica Bond III IHC stainer

CLDN18.2 expression ≥10%/≥1+ was reported in the majority of G/GEJ adenocarcinoma samples, while PD L1 CPS ≥ 5 was only observed in 17% of the total samples. No correlation between the two markers expression was observed.

These results support the value of CLDN18.2 targeted therapy in gastric cancer, especially for those patients who may not benefit from anti PD 1/PD L1 immuno checkpoint therapy.

Limitation of this retrospective study: All tumor samples were from surgical resections of G/GEJ adenocarcinoma in Chinese patients, with limited samples from metastatic lesions and no clinical annotations. Further explorations of the expression of CLDN18.2, PD L1 CPS and their correlation, the impact of stage of disease, biopsy location and ethnicity is required.