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Node-sparing modified short-course Radiotherapy Combined with CAPOX and Tislelizumab for locally Advanced MSS of Middle and low rectal Cancer (mRCAT): an open-label, single-arm, prospective, multicentre clinical trial

Authors :
Cheng Cai
Xia Zhang
Xiaonan Sun
Huogang Wang
Engeng Chen
Li Chen
Benxing Gu
Jianping Wang
Xuefeng Huang
Weifeng Lao
Xiaowei Wang
Min Chen
Shubo Ding
Jinlin Du
Zhangfa Song
Source :
BMC Cancer, Vol 24, Iss 1, Pp 1-7 (2024)
Publication Year :
2024
Publisher :
BMC, 2024.

Abstract

Abstract Background Neoadjuvant chemoradiotherapy followed by total mesorectal excision is a standard treatment for locally advanced rectal cancer. Mismatch repair-deficient locally advanced rectal cancer (LARC) was highly sensitive to PD-1 blockade. However, most rectal cancers are microsatellite stable (MSS) or mismatch repair-proficient (pMMR) subtypes for which PD-1 blockade is ineffective. Radiation can trigger the activation of CD8 + T cells, further enhancing the responses of MSS/pMMR rectal cancer to PD-1 blockade. Radioimmunotherapy offers a promising therapeutic modality for rectal cancer. Progenitor T exhausted cells are abundant in tumour-draining lymph nodes and play an important role in immunotherapy. Conventional irradiation fields include the mesorectum and regional lymph nodes, which might cause considerable damage to T lymphocytes and radiation-induced fibrosis, ultimately leading to a poor response to immunotherapy and rectal fibrosis. This study investigated whether node-sparing modified short-course irradiation combined with chemotherapy and PD-1 blockade could be effective in patients with MSS/ pMMR LARC. Methods This was a open-label, single-arm, multicentre, prospective phase II trial. 32 LARC patients with MSS/pMMR will receive node-sparing modified short-course radiotherapy (the irradiated planned target volume only included the primary tumour bed but not the tumour-draining lymph nodes, 25 Gy/5f, 5 Gy/f) followed by CAPOX and tislelizumab. CAPOX and tislelizumab will be started two days after the completion of radiotherapy: oxaliplatin 130 mg/m2 intravenous infusion, day 1; capecitabine 1000 mg/m2 oral administration, days 1–14; and tislelizumab 200 mg, intravenous infusion, day 1. There will be four 21-day cycles. TME will be performed at weeks 14–15. We will collect blood, tumour, and lymphoid specimens; perform flow cytometry and in situ multiplexed immunofluorescence detection; and analyse the changes in various lymphocyte subsets. The primary endpoint is the rate of pathological complete response. The organ preservation rate, tumour regression grade, local recurrence rate, disease-free survival, overall survival, adverse effects, and quality of life will also be analysed. Discussion In our research, node-sparing modified radiotherapy combined with immunotherapy probably increased the responsiveness of immunotherapy for MSS/pMMR rectal cancer patients, reduced the occurrence of postoperative rectal fibrosis, and improved survival and quality of life. This is the first clinical trial to utilize a node-sparing radiation strategy combined with chemotherapy and PD-1 blockade in the neoadjuvant treatment of rectal cancer, which may result in a breakthrough in the treatment of MSS/pMMR rectal cancer. Trial registration This study was registered at www.clinicaltrials.gov . Trial registration number: NCT05972655. Date of registration: 31 July 2023.

Details

Language :
English
ISSN :
14712407
Volume :
24
Issue :
1
Database :
Directory of Open Access Journals
Journal :
BMC Cancer
Publication Type :
Academic Journal
Accession number :
edsdoj.298fbfc86d9f426ea7c57f5b038fe729
Document Type :
article
Full Text :
https://doi.org/10.1186/s12885-024-12994-0