{
  "abstract": "Colorectal cancer with proficient mismatch repair (pMMR)/microsatellite stable (MSS) status is generally intrinsically resistant to immune checkpoint inhibitors; tumors with concomitant BRAF V600E mutations are highly aggressive, and conventional chemotherapy and targeted therapies have limited efficacy, resulting in a lack of effective personalized treatment options in clinical practice. This report describes a case of locally advanced right-sided colon adenocarcinoma that was pMMR/MSS, harbored a BRAF V600E mutation, and exhibited high programmed death-ligand 1 (PD-L1) expression (tumor proportion score [TPS] > 95%). The patient developed intestinal obstruction after failure of first-line conversion therapy. After undergoing palliative gastrojejunostomy and cecostomy, she developed gastroparesis and a liver abscess. Given the extremely high PD-L1 expression, tislelizumab monotherapy was initiated before the patient’s general condition had fully recovered. After three cycles, the patient’s performance status improved significantly. She then received a combination of tislelizumab and raltitrexed for two cycles; however, chemotherapy was discontinued due to raltitrexed-induced liver injury, and the patient continued maintenance therapy with tislelizumab monotherapy, achieving a partial response (PR) as the best outcome. After nine cycles of maintenance therapy, a new mass appeared in the right adnexal region, indicating disease progression; the overall progression-free survival (PFS) was 14 months. To the best of our knowledge, this is the first reported case of a patient with colorectal adenocarcinoma harboring a BRAF V600E mutation, characterized by extremely high PD-L1 expression and pMMR/MSS status, who achieved a PR with a regimen centered on programmed cell death protein 1 (PD-1) inhibitor monotherapy. This case suggests that for BRAF V600E-mutated colorectal cancer, assessment of PD-L1 expression levels should be considered regardless of mismatch repair status; if extremely high PD-L1 expression is present, even in the pMMR/MSS phenotype, PD-1 inhibitors may offer a potential personalized treatment option for these patients with poor prognosis and limited therapeutic choices.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Case Report",
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "name": "Chen Li"
    },
    {
      "name": "Mingyan Li"
    },
    {
      "name": "Simin Wang"
    },
    {
      "name": "Mingxin Xu"
    },
    {
      "name": "Haiyan Liu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1f2nv9wpza67x.bib",
  "cited_by": 0,
  "doi": "10.3389/fonc.2026.2004627",
  "fulltext_url": null,
  "id": "1f2nv9wpza67x",
  "issns": [
    "2234-943X"
  ],
  "landing_url": "https://www.frontiersin.org/articles/10.3389/fonc.2026.2004627",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "feed-journal",
      "medicine/oncology"
    ]
  ],
  "openalex": null,
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-06",
  "publisher": "Frontiers Media SA",
  "ris": "https://research.draconitic.com/paper/1f2nv9wpza67x.ris",
  "sources": [
    {
      "first_seen": "2026-11-06T06:20:07Z",
      "native_id": "10.3389/fonc.2026.2004627",
      "source": "feed-frontiers",
      "url": "https://www.frontiersin.org/articles/10.3389/fonc.2026.2004627"
    },
    {
      "first_seen": "2026-11-06T12:21:22Z",
      "native_id": "10.3389/fonc.2026.2004627",
      "source": "crossref",
      "url": "https://www.frontiersin.org/articles/10.3389/fonc.2026.2004627/full"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "feed-journal:medicine/oncology",
      "subfield": "oncology"
    }
  ],
  "title": "Case Report: Durable response to tislelizumab monotherapy in microsatellite-stable, BRAF V600E-mutant right-sided colon cancer with extremely high PD-L1 expression",
  "title_text": "Case Report: Durable response to tislelizumab monotherapy in microsatellite-stable, BRAF V600E-mutant right-sided colon cancer with extremely high PD-L1 expression",
  "type": "peer-reviewed",
  "updated_at": "2026-11-08T00:23:06Z",
  "url": "https://research.draconitic.com/paper/1f2nv9wpza67x",
  "venue": "Frontiers in Oncology",
  "versions": []
}