Case report: Complete response to pembrolizumab in a liver metastatic colon adenocarcinoma patient with a novel likely pathogenic germline MSH2 mutation

• DOI: 10.3389/fimmu.2022.1064488
• Publication Date: 2022-11-28T06:58:50Z
• Authors: Yanjie Xu; Qin Li; Jiemin Zhao; Xuefeng Ni; Ping Li; Wenwei Hu
• Keywords: Lynch Syndrome; MSH2; MSH6; MLH1; Microsatellite Instability

Lynch syndrome (LS) is a genetic disorder mainly caused by germline mutations in mismatched repair (MMR) genes ( MSH2 , MLH1 MSH6 and PMS2 ) or deletions of the epithelial cell adhesion molecule gene EPCAM ). A 43-year-old Chinese male patient underwent radical surgery was pathologically confirmed to have stage IIIB colon adenocarcinoma. After four cycles standard adjuvant chemotherapy, tumor reoccurred situ with intestinal obstruction. The received secondary colectomy. Immunohistochemistry analysis revealed loss protein expression surgical specimen. Noticing that patient’s mother grandfather all were diagnosed LS-related cancers, we collected his mother’s peripheral blood for testing, result showed six-base deletion . Thus, concluded our had LS. Subsequently, accepted pembrolizumab as first-line systemic therapy after liver metastases. He achieved clinical complete response (cCR) within 2 months remained progression-free more than years. case report mutation (c.489_494deTGGGTA) likely pathogenic mutation, immunotherapy (pembrolizumab) effective this patient.