261MO - Real-world data on prevalence of MSI-H/dMMR across 6 solid tumor types in Asia

Background

Data on the prevalence of microsatellite instability-high (MSI-H)/deficient mismatch repair (dMMR) in patients with advanced solid tumors from Asia are limited and are needed to aid treatment decisions in the clinical setting. We present real-world data on MSI-H/dMMR across 6 tumor types in Asian patients.

Methods

Patients aged ≥18 y with advanced (stage III/IV) gastrointestinal (GI; biliary tract, gastric, pancreatic) and gynecologic (GYN; cervical, endometrial, ovarian) tumors, regardless of prior therapy, from 29 study centers in Asia-Pacific (Korea, Singapore, Taiwan) and Japan were analyzed. Biomarker testing was performed on archival formalin-fixed paraffin-embedded tissue samples using the Ventana MMR RxDx Panel in patients from Asia-Pacific. Retrospective data on MSI-H PCR status (via MSI-IVD Kit [FALCO]) in patients from Japan were collected. The primary objective was to evaluate the prevalence of MSI-H/dMMR status. Secondary objectives included assessment of clinicopathologic characteristics and treatment patterns.

Results

MSI-H/dMMR status was evaluable in 1970 patients; 980 (49.7%) had GI tumors and 990 (50.3%) had GYN tumors. Prevalence of MSI-H/dMMR was 5.4% (106/1970) in the overall population, 2.8% (27/980) in GI tumors, and 8.0% (79/990) in GYN tumors. Prevalence of MSI-H/dMMR was highest in endometrial cancer in Asia-Pacific (14.6%) and Japan (21.7%) (Table). Most patients in the MSI-H/dMMR population had ECOG PS of 0 or 1 (92.4%) and had undergone surgery (74.5%) and/or received chemotherapy (95.3%) since initial diagnosis. Notably, immune checkpoint inhibitors (ICIs) were administered to a greater proportion of patients with MSI-H/dMMR tumors (34.0%) than to patients with non–MSI-H/proficient MMR tumors (7.2%); most (77.8%) of the MSI-H/dMMR population received ICIs in the second-line or later setting. Table: 261MO

Prevalence of MSI-H/dMMR across tumor types in the overall population and regional cohorts

Conclusions

The prevalence of MSI-H/dMMR across the 6 tumor types in this analysis of Asian patients was consistent with literature reports on non-Asian patients.

Clinical trial identification

Editorial acknowledgement

Medical writing and/or editorial assistance was provided by Obinna T. Ezeokoli, PhD, and Holly C. Cappelli, PhD, CMPP, of ApotheCom (Yardley, PA, USA). This assistance was funded by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.

Legal entity responsible for the study

Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.

Funding

MSD International GmbH (Singapore Branch).

Disclosure

D.S.S.P. Tan: Financial Interests, Personal, Other, Consultancy fees: AstraZeneca, Roche, MSD, Merck Serono, Bayer, Eisai; Financial Interests, Institutional, Research Grant: AstraZeneca, Bayer, Roche, Karyopharm; Financial Interests, Personal, Stocks/Shares: Asian Microbiome Library (AMiLi); Financial Interests, Personal and Institutional, Funding: Singapore Ministry of Health’s National Medical Research Council Clinician Scientist Award and Pangestu Family Foundation Gynaecological Cancer Research Fund. Y.M. Kim: Financial Interests, Institutional, Research Grant: MSD, AstraZeneca, Roche, Regeneron, Clovis Oncology. C. Lu: Financial Interests, Institutional, Principal Investigator: Taichung Veterans General Hospital. M. Kanai: Financial Interests, Personal, Stocks/Shares: Therabiopharma Inc.; Financial Interests, Personal, Advisory Role: Therabiopharma Inc.; Financial Interests, Personal, Speaker’s Bureau: Chugai Pharmaceutical Co., Ltd.; Financial Interests, Institutional, Research Grant: Molecular Health. S.Y. Rha: Other, Personal, Advisory Role: Amgen, Daichii Sankyo, BMS, Indivumed, Merck, BeiGene, Eisai. R. Ramar, M. Wong: Financial Interests, Personal, Full or part-time Employment: MSD International GmbH; Financial Interests, Personal, Stocks/Shares: MSD International GmbH. All other authors have declared no conflicts of interest.