Salvage treatment of a metastatic colorectal cancer with pMMR/MSS in a 21-year-old man: a case report

In metastatic colorectal cancer (mCRC) patients with proficient mismatch repair (pMMR)/microsatellite stability (MSS), beyond third-line therapies were extremely limited. Here, we reported a case of a 21-year-old male patient with pMMR/MSS mCRC who failed to respond to both first- and second-line tr...

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Main Authors: Xuesong Li, Hao Liu, Zhuo Yu
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-08-01
Series:Frontiers in Oncology
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Online Access:https://www.frontiersin.org/articles/10.3389/fonc.2025.1567760/full
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author Xuesong Li
Hao Liu
Zhuo Yu
author_facet Xuesong Li
Hao Liu
Zhuo Yu
author_sort Xuesong Li
collection DOAJ
description In metastatic colorectal cancer (mCRC) patients with proficient mismatch repair (pMMR)/microsatellite stability (MSS), beyond third-line therapies were extremely limited. Here, we reported a case of a 21-year-old male patient with pMMR/MSS mCRC who failed to respond to both first- and second-line treatment and subsequently received non-standard third-line therapy at a local hospital. This patient was referred to our hospital, and we initiated salvage therapies. The fourth-line treatment, including tislelizumab, regorafenib, pemetrexed, and raltitrexed, was administered with a progression-free survival (PFS) of 13 months. Then, this patient received fifth-line treatment with chidamide, fruquintinib, toripalimab, raltitrexed, and nanoparticle albumin-bound paclitaxel with a PFS of 8 months. During the whole treatment, side effects were tolerable and significantly alleviated with appropriate symptomatic therapies. In addition, cystoscopy plus transurethral resection of a metastatic bladder tumor was successfully conducted to halt the bleeding. The sixth-line regimen was started, and he is still under follow-up. Collectively, this patient achieved long-term survival with a high quality of life through therapies beyond the third line.
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spelling doaj-art-b0cfd0b7beed47b0b21e41bc9d9220ea2025-08-22T04:10:33ZengFrontiers Media S.A.Frontiers in Oncology2234-943X2025-08-011510.3389/fonc.2025.15677601567760Salvage treatment of a metastatic colorectal cancer with pMMR/MSS in a 21-year-old man: a case reportXuesong Li0Hao Liu1Zhuo Yu2Department of Medical Oncology, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua Medicine, Tsinghua University, Beijing, ChinaDepartment of Pathology, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua Medicine, Tsinghua University, Beijing, ChinaDepartment of Medical Oncology, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua Medicine, Tsinghua University, Beijing, ChinaIn metastatic colorectal cancer (mCRC) patients with proficient mismatch repair (pMMR)/microsatellite stability (MSS), beyond third-line therapies were extremely limited. Here, we reported a case of a 21-year-old male patient with pMMR/MSS mCRC who failed to respond to both first- and second-line treatment and subsequently received non-standard third-line therapy at a local hospital. This patient was referred to our hospital, and we initiated salvage therapies. The fourth-line treatment, including tislelizumab, regorafenib, pemetrexed, and raltitrexed, was administered with a progression-free survival (PFS) of 13 months. Then, this patient received fifth-line treatment with chidamide, fruquintinib, toripalimab, raltitrexed, and nanoparticle albumin-bound paclitaxel with a PFS of 8 months. During the whole treatment, side effects were tolerable and significantly alleviated with appropriate symptomatic therapies. In addition, cystoscopy plus transurethral resection of a metastatic bladder tumor was successfully conducted to halt the bleeding. The sixth-line regimen was started, and he is still under follow-up. Collectively, this patient achieved long-term survival with a high quality of life through therapies beyond the third line.https://www.frontiersin.org/articles/10.3389/fonc.2025.1567760/fullcolorectal cancerproficient mismatch repair/microsatellite stabilityPD-1 inhibitorchidamidetreatment
spellingShingle Xuesong Li
Hao Liu
Zhuo Yu
Salvage treatment of a metastatic colorectal cancer with pMMR/MSS in a 21-year-old man: a case report
Frontiers in Oncology
colorectal cancer
proficient mismatch repair/microsatellite stability
PD-1 inhibitor
chidamide
treatment
title Salvage treatment of a metastatic colorectal cancer with pMMR/MSS in a 21-year-old man: a case report
title_full Salvage treatment of a metastatic colorectal cancer with pMMR/MSS in a 21-year-old man: a case report
title_fullStr Salvage treatment of a metastatic colorectal cancer with pMMR/MSS in a 21-year-old man: a case report
title_full_unstemmed Salvage treatment of a metastatic colorectal cancer with pMMR/MSS in a 21-year-old man: a case report
title_short Salvage treatment of a metastatic colorectal cancer with pMMR/MSS in a 21-year-old man: a case report
title_sort salvage treatment of a metastatic colorectal cancer with pmmr mss in a 21 year old man a case report
topic colorectal cancer
proficient mismatch repair/microsatellite stability
PD-1 inhibitor
chidamide
treatment
url https://www.frontiersin.org/articles/10.3389/fonc.2025.1567760/full
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