{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,29]],"date-time":"2026-05-29T12:56:56Z","timestamp":1780059416330,"version":"3.54.0"},"reference-count":14,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,4,20]],"date-time":"2026-04-20T00:00:00Z","timestamp":1776643200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Oncol."],"abstract":"<jats:p>Patients with metastatic colorectal cancer (mCRC) harboring both microsatellite instability\u2013high\/deficient mismatch repair (MSI-H\/dMMR) and the BRAF V600E mutation represent a distinct clinicomolecular subgroup characterized by aggressive biology and distinct therapeutic challenges. While MSI-H\/dMMR predicts sensitivity to immune checkpoint inhibitors (ICIs), the concurrent BRAF V600E mutation may contribute to secondary resistance or shortened durability of response in a subset of patients treated with ICI monotherapy. Here, we present the case of an 85-year-old female with locally advanced ascending colon cancer who experienced rapid recurrence and metastasis only four months after radical surgery. Molecular profiling confirmed MSI-H, dMMR, and BRAF V600E mutation. Given her advanced age and frailty, she was treated with a first-line combination of pembrolizumab, dabrafenib, and trametinib. Although the targeted therapy (dabrafenib\/trametinib) was discontinued after approximately two months due to recurrent high-grade pyrexia, the patient continued on pembrolizumab maintenance. She achieved a radiographic complete response (CR) and has remained progression-free for over 26 months. This case highlights the potential synergy between MAPK pathway inhibition and immunotherapy, suggesting that even short-course targeted therapy may favorably remodel the tumor microenvironment to enable durable disease control in high-risk MSI-H\/BRAF-mutant mCRC.<\/jats:p>","DOI":"10.3389\/fonc.2026.1764072","type":"journal-article","created":{"date-parts":[[2026,4,20]],"date-time":"2026-04-20T04:14:15Z","timestamp":1776658455000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Durable complete response to pembrolizumab after BRAF\/MEK inhibition in recurrent MSI-H\/dMMR, BRAF V600E\u2013mutant colon cancer: a case report"],"prefix":"10.3389","volume":"16","author":[{"given":"Wenyan","family":"Yu","sequence":"first","affiliation":[{"name":"Department of Oncology, Shanghai Fourth People\u2019s Hospital, Tongji University School of Medicine","place":["Shanghai, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kaichun","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Oncology, Shanghai Fourth People\u2019s Hospital, Tongji University School of Medicine","place":["Shanghai, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,4,20]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1126\/science.aan6733","article-title":"Mismatch repair deficiency predicts response of solid tumors to PD-1 blockade","volume":"357","author":"Le","year":"2017","journal-title":"Science"},{"key":"B2","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa2017699","article-title":"Pembrolizumab in microsatellite-instability-high advanced colorectal cancer","volume":"383","author":"Andre","year":"2020","journal-title":"N Engl J 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Oncology"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fonc.2026.1764072\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,20]],"date-time":"2026-04-20T04:14:17Z","timestamp":1776658457000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fonc.2026.1764072\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,4,20]]},"references-count":14,"alternative-id":["10.3389\/fonc.2026.1764072"],"URL":"https:\/\/doi.org\/10.3389\/fonc.2026.1764072","relation":{},"ISSN":["2234-943X"],"issn-type":[{"value":"2234-943X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,4,20]]},"article-number":"1764072"}}