{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T20:14:52Z","timestamp":1789676092719,"version":"4.0.1"},"reference-count":37,"publisher":"American Society of Clinical Oncology (ASCO)","issue":"9","content-domain":{"domain":["ascopubs.org"],"crossmark-restriction":true},"short-container-title":["JCO Precis Oncol"],"published-print":{"date-parts":[[2026,9]]},"abstract":"<jats:sec>\n                    <jats:title>PURPOSE<\/jats:title>\n                    <jats:p>Microsatellite instability-high (MSI-H) and deficient mismatch repair (dMMR) gastric or gastroesophageal junction (GEJ) adenocarcinomas are biologically distinct tumors with established sensitivity to immune checkpoint inhibitors (ICIs). However, real-world treatment patterns, response heterogeneity, and predictors of durable benefit remain poorly defined.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>METHODS<\/jats:title>\n                    <jats:p>We retrospectively analyzed patients with biopsy-confirmed MSI-H\/dMMR gastric\/GEJ adenocarcinoma treated at a single center. Clinicopathologic, genomic, treatment, and outcome data were collected. Molecular profiling included ARID1A, RNF43, TP53, PIK3CA, KRAS, TGFBR2, and human epidermal growth factor 2 (HER2). ICIs-treated patients were classified as achieving clinical benefit (complete response, partial response, or durable stable disease \u226516 weeks) or no clinical benefit using iRECIST v1.1 and clinical assessment. Overall survival (OS) was estimated by using the Kaplan-Meier method.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>RESULTS<\/jats:title>\n                    <jats:p>\n                      Thirty-four patients were identified (median age, 66 years; 53% male), including 21 with stage IV disease. Tumors were predominantly poorly differentiated (65%) and HER2-negative (94%), and 18% of patients had Lynch syndrome. Among 22 ICI-treated patients, 55% achieved clinical benefit, which was strongly associated with prolonged OS (\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      &lt; .01). Most responses occurred at the first radiographic assessment (approximately 12 weeks). Elevated tumor mutational burden (TMB; \u226520 mutations\/Mb) was present in 56% of patients but was not associated with clinical benefit (\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      = .40), and no individual genomic alteration significantly correlated with treatment outcome. Exploratory analyses suggested longer OS among patients with liver versus peritoneal metastases. Treatment was well tolerated, with predominantly low-grade immune-related adverse events. Baseline Eastern Cooperative Oncology Group performance status (0-1\n                      <jats:italic toggle=\"yes\">v<\/jats:italic>\n                      \u2265 2) was associated with clinical benefit (\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      = .049).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>CONCLUSION<\/jats:title>\n                    <jats:p>Approximately half of the patients with MSI-H\/dMMR gastric\/GEJ adenocarcinoma cancers derived durable clinical benefit from ICIs, and treatment response was strongly associated with survival. Conventional genomic features, including TMB, did not predict clinical benefit, highlighting the need for additional biomarkers.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1200\/po-26-00543","type":"journal-article","created":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T19:59:13Z","timestamp":1789675153000},"update-policy":"https:\/\/doi.org\/10.1200\/crossmark","source":"Crossref","is-referenced-by-count":0,"title":["Clinicopathologic Features, Treatment Patterns, and Outcomes of Microsatellite Instability-High Gastric and Gastroesophageal Junction Adenocarcinoma: A Single-Institution Retrospective Analysis"],"prefix":"10.1200","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5762-6683","authenticated-orcid":true,"given":"Dani","family":"Castillo","sequence":"first","affiliation":[{"name":"Department of Medical Oncology and Therapeutics Research, City of Hope, Duarte, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-0331-892X","authenticated-orcid":true,"given":"Pranati","family":"Shah","sequence":"additional","affiliation":[{"name":"Loma Linda University Medical Center, Internal Medicine, Loma Linda, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-9416-0555","authenticated-orcid":true,"given":"Natasha","family":"Setia","sequence":"additional","affiliation":[{"name":"Department of Medical Oncology and Therapeutics Research, City of Hope, Duarte, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sofia","family":"Guzman","sequence":"additional","affiliation":[{"name":"Department of Medical Oncology and Therapeutics Research, City of Hope, Duarte, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sadia","family":"Mlamba","sequence":"additional","affiliation":[{"name":"Department of Ambulatory Care, City of Hope, Duarte, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6461-5560","authenticated-orcid":true,"given":"Derek","family":"Tai","sequence":"additional","affiliation":[{"name":"Loma Linda University Medical Center, Internal Medicine, Loma Linda, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fei","family":"Fei","sequence":"additional","affiliation":[{"name":"Department of Pathology, City of Hope, Duarte, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dalilah","family":"Perez","sequence":"additional","affiliation":[{"name":"Department of Ambulatory Care, City of Hope, Duarte, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-5496-4362","authenticated-orcid":true,"given":"Cecilia","family":"Lau","sequence":"additional","affiliation":[{"name":"Department of Pharmacy Services, City of Hope, Duarte, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0438-8626","authenticated-orcid":true,"given":"Max","family":"Hazeltine","sequence":"additional","affiliation":[{"name":"Department of Surgery, City of Hope, Duarte, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6676-0593","authenticated-orcid":true,"given":"Yanghee","family":"Woo","sequence":"additional","affiliation":[{"name":"Department of Surgery, City of Hope, Duarte, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3174-311X","authenticated-orcid":true,"given":"Gagandeep","family":"Brar","sequence":"additional","affiliation":[{"name":"Department of Medical Oncology and Therapeutics Research, City of Hope, Duarte, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6554-5488","authenticated-orcid":true,"given":"Marwan","family":"Fakih","sequence":"additional","affiliation":[{"name":"Department of Medical Oncology and Therapeutics Research, City of Hope, Duarte, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shengyang Peter","family":"Wu","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, Mount Sinai Comprehensive Cancer Care, Paramus, NJ"},{"name":"Department of Radiation Oncology, Icahn School of Medicine at Mount Sinai, New York, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rifat","family":"Mannan","sequence":"additional","affiliation":[{"name":"Department of Pathology, City of Hope, Duarte, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"233","reference":[{"key":"e_1_3_8_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.seminoncol.2025.152341"},{"key":"e_1_3_8_3_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(20)31288-5"},{"key":"e_1_3_8_4_2","doi-asserted-by":"publisher","DOI":"10.1001\/jamaoncol.2021.0275"},{"key":"e_1_3_8_5_2","doi-asserted-by":"publisher","DOI":"10.1158\/1078-0432.CCR-21-1935"},{"key":"e_1_3_8_6_2","doi-asserted-by":"publisher","DOI":"10.3389\/fonc.2022.908026"},{"key":"e_1_3_8_7_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.ctrv.2021.102175"},{"key":"e_1_3_8_8_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(25)00052-2"},{"key":"e_1_3_8_9_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.dnarep.2020.102918"},{"key":"e_1_3_8_10_2","first-page":"948","article-title":"Global burden, risk factors, clinicopathological characteristics, molecular biomarkers and outcomes of microsatellite instability-high gastric cancer","volume":"16","author":"Zhang Z","year":"2024","unstructured":"Zhang Z, Huang J, Li Y, et al: Global burden, risk factors, clinicopathological characteristics, molecular biomarkers and outcomes of microsatellite instability-high gastric cancer. Aging (Albany NY) 16:948-963, 2024","journal-title":"Aging (Albany NY)"},{"key":"e_1_3_8_11_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-023-48157-7"},{"key":"e_1_3_8_12_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.esmoop.2020.100036"},{"key":"e_1_3_8_13_2","doi-asserted-by":"publisher","DOI":"10.3748\/wjg.v30.i21.2734"},{"key":"e_1_3_8_14_2","doi-asserted-by":"publisher","DOI":"10.1002\/cam4.3417"},{"key":"e_1_3_8_15_2","doi-asserted-by":"publisher","DOI":"10.1097\/SLA.0000000000005501"},{"key":"e_1_3_8_16_2","doi-asserted-by":"publisher","DOI":"10.1200\/JCO.22.02331"},{"key":"e_1_3_8_17_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejca.2008.10.026"},{"key":"e_1_3_8_18_2","doi-asserted-by":"publisher","DOI":"10.1016\/0197-2456(96)00075-X"},{"key":"e_1_3_8_19_2","doi-asserted-by":"publisher","DOI":"10.1177\/17588359241231259"},{"key":"e_1_3_8_20_2","doi-asserted-by":"publisher","DOI":"10.1007\/s00018-018-2906-9"},{"key":"e_1_3_8_21_2","doi-asserted-by":"publisher","DOI":"10.1007\/s10689-021-00235-3"},{"key":"e_1_3_8_22_2","doi-asserted-by":"publisher","DOI":"10.1007\/s10120-024-01523-4"},{"key":"e_1_3_8_23_2","doi-asserted-by":"publisher","DOI":"10.1177\/17588359231162577"},{"key":"e_1_3_8_24_2","doi-asserted-by":"publisher","DOI":"10.3390\/jcm12072636"},{"key":"e_1_3_8_25_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41698-021-00172-5"},{"key":"e_1_3_8_26_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41591-018-0101-z"},{"key":"e_1_3_8_27_2","doi-asserted-by":"publisher","DOI":"10.3390\/curroncol30020145"},{"key":"e_1_3_8_28_2","doi-asserted-by":"publisher","DOI":"10.1158\/2159-8290.CD-21-0219"},{"key":"e_1_3_8_29_2","doi-asserted-by":"publisher","DOI":"10.1186\/s13045-024-01578-x"},{"key":"e_1_3_8_30_2","doi-asserted-by":"publisher","DOI":"10.3389\/fimmu.2023.1210164"},{"key":"e_1_3_8_31_2","doi-asserted-by":"publisher","DOI":"10.1136\/jitc-2021-004001"},{"key":"e_1_3_8_32_2","doi-asserted-by":"publisher","DOI":"10.1186\/s13045-019-0738-1"},{"key":"e_1_3_8_33_2","doi-asserted-by":"publisher","DOI":"10.1093\/oncolo\/oyae152"},{"key":"e_1_3_8_34_2","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa2400634"},{"key":"e_1_3_8_35_2","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa2404512"},{"key":"e_1_3_8_36_2","doi-asserted-by":"publisher","unstructured":"Sahwan O Jamal F Pai R et al: Immune checkpoint inhibitors for mismatch repair-deficient gastroesophageal adenocarcinoma: Outcomes and feasibility of nonoperative management at Mayo Clinic. JCO Precis Oncol 10.1200\/PO-25-00492","DOI":"10.1200\/PO-25-00492"},{"key":"e_1_3_8_37_2","doi-asserted-by":"publisher","DOI":"10.1186\/s12885-019-6150-y"},{"key":"e_1_3_8_38_2","doi-asserted-by":"publisher","DOI":"10.21873\/invivo.12281"}],"container-title":["JCO Precision Oncology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/ascopubs.org\/doi\/pdfdirect\/10.1200\/PO-26-00543","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T19:59:21Z","timestamp":1789675161000},"score":1,"resource":{"primary":{"URL":"https:\/\/ascopubs.org\/doi\/10.1200\/PO-26-00543"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9]]},"references-count":37,"journal-issue":{"issue":"9","published-print":{"date-parts":[[2026,9]]}},"alternative-id":["10.1200\/PO-26-00543"],"URL":"https:\/\/doi.org\/10.1200\/po-26-00543","relation":{},"ISSN":["2473-4284"],"issn-type":[{"value":"2473-4284","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9]]},"assertion":[{"value":"2026-05-08","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-07-13","order":1,"name":"revised","label":"Revised","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-07-31","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-09-17","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"e2600543"}}