{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,25]],"date-time":"2026-03-25T17:15:40Z","timestamp":1774458940253,"version":"3.50.1"},"reference-count":13,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2021,5,25]],"date-time":"2021-05-25T00:00:00Z","timestamp":1621900800000},"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>Colorectal squamous cell carcinoma (SCC) is extremely rare and associated with a poor prognosis. And the pMMR\/MSS colorectal cancer is related to a limited response to programmed death ligand-1 (PD-1) blockade monotherapy. However, the clinical activity of PD-1 blockade monotherapy or combination therapy in colorectal SCC is unknown. One patient with rectosigmoid-junction SCC was treated with PD-1 blockade combined with chemotherapy. After 3 months of PD-1 blockade and chemotherapy, the computed tomography imaging showed that this patient achieved a partial response. The next generation sequencing and immunohistochemistry analysis showed that the patient had tumors with proficient mismatch repair (pMMR) and microsatellite stability (MSS), strong PD-L1 expression, and tumor mutational burden-high (TMB-High), respectively. This case suggests that PD-1 blockade combined with chemotherapy might be an effective therapy for colorectal SCC with pMMR\/MSS status. Moreover, the PD-L1 expression and TMB might be the potential predictors of PD-1 blockade response for colorectal SCC patients.<\/jats:p>","DOI":"10.3389\/fonc.2021.596342","type":"journal-article","created":{"date-parts":[[2021,5,25]],"date-time":"2021-05-25T06:37:25Z","timestamp":1621924645000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":6,"title":["Rectosigmoid-Junction Squamous Cell Carcinoma With pMMR\/MSS Achieved a Partial Response Following PD-1 Blockade Combined With Chemotherapy: A Case 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