1562P - Claudin 18.2 expression in resected gastric cancer

Background

Zolbetuximab showed efficacy for gastric cancer with Claudin (CLDN)18.2 expression. CLDN18.2 is reported to be expressed in about 20-50% of gastric cancer, but the definitions varied in previous reports and the relationship with prognosis is controversial. The present study aimed to examine the expression of CLDN18.2 based on SPOTLIGHT/GLOW study and the relationship with prognosis and clinical/molecular characteristics in resected gastric cancer.

Methods

We used a tissue microarray set including gastric cancer samples resected in our institution between July 1989 and September 2009. VENTANA CLDN18 (43-14A) assay was used for immunohistochemistry (IHC) of CLDN18.2. CLDN18.2 expression was judged as positive when ≥75% of the tumor cell membrane was stained in moderate-to-strong intensity by IHC. The Combined Positive Score (CPS) was evaluated using Dako PD-L1 28-8 pharmDx assay.

Results

CLDN18.2 was evaluable in 366 samples and expressed in 139 samples (38%). Clinical data was available in 129 patients (pts) with CLDN18.2+ vs 191 CLDN18.2- pts. Patient characteristics in the CLDN18.2+ group vs the CLDN18.2- group were as follows; median age (range), 64 (27 - 85) vs 66 (35 - 83); gender male 94 (73%) vs 139 (73%); HER2 positive 11 (10%) vs 19 (10%); CPS ≥5, 64 (50%) vs 88 (46%); dMMR, 4 (3.1%) vs 5 (2.6%); Lauren classification diffuse, 71 (55%) vs 107 (56%); pTstage 1/2/3/4, 13/15/17/84 vs 17/34/28/112; pNstage 0/1/2/3, 27/31/32/39 vs 41/39/50/61; pStage I/II/III, 13/36/80 vs 14/68/109; and adjuvant S-1, 43 (33%) vs 54 (28%). Three-year RFS was 56.8% in the CLDN18.2+ group vs 60.3% in the CLDN18.2- group (HR = 1.07 [95% CI 0.77-1.49], p = 0.68). Three-year OS was 66.9% in the CLDN18.2+ group vs 68.7% in the CLDN18.2- group (HR = 1.13 [95% CI 0.80-1.59], p = 0.49).

Conclusions

CLDN18.2 expression was observed in 38% of resected gastric cancer samples, which was consistent with previous reports. CLDN18.2 expression was not related to prognosis and specific relationship was not observed in clinical/molecular characteristics of resected gastric cancer.

Clinical trial identification

Editorial acknowledgement

The Authors would like to thank Charles McKay for English language editing.

Legal entity responsible for the study

M. Furuta.

Funding

Has not received any funding.

Disclosure

M. Furuta: Financial Interests, Personal, Invited Speaker: Eli Lilly, Bristol Myers Squibb, Merck & Co., Inc., Ono Pharamceutical Co. Ltd., , Takeda Pharmaceutical Company Limited. N. Machida: Financial Interests, Personal, Invited Speaker: Bristol Myers Squibb, Ono, Taiho, MSD, Daiichi Sankyo, Yakult, Eli Lilly Japan, Chugai, Astellas, Takeda, Merck biopharma, Nichi-Iko, Nippon-Kayaku; Financial Interests, Institutional, Local PI: Bristol Myers Squibb, Ono, Daiichi Sankyo, Astellas, MSD, Amgen, ALX Oncology, Seagen. J. Furuse: Financial Interests, Personal, Invited Speaker: Ono Pharmaceutical, Bayer, Eisai, Eli Lilly Japan, MSD, Yakult Honsha, Chugai Pharma, Novartis Pharma, AstraZeneca, Pfizer, Takeda, Taiho Pharmaceutical, Sanofi, Mylan EPD, EA Pharma, Kyowa Hakko Kirin, Daiichi Sankyo, Teijin pharma, Servier Japan, Incyte; Financial Interests, Personal, Advisory Board: Fuji film, Mudi Pharma, Onco Therapy Science, Merck Bio, Ono Pharmaceutical, MSD, Taiho Pharmaceutical, Chugai Pharma, Astellas, AstraZeneca, Takara bio, Delta-Fly-Pharma, Incyte Japan; Financial Interests, Institutional, Research Grant: Ono Pharmaceutical, MSD, Merck Bio, J-Pharma, Taiho Pharmaceutical, Takeda, Chugai Pharma, AstraZeneca, Yakult Honsha, Eisai, Daiichi Sankyo, Mochida, Sanofi, Sumitomo Dainippon Bayer, Astellas, Incyte Japan; Financial Interests, Personal, Steering Committee Member: Merck Bio, Ono Pharmaceutical, MSD, Taiho Pharmaceutical, Astellas, AstraZeneca, Incyte Japan. All other authors have declared no conflicts of interest.