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For patients with locally recurrent rectal cancer (LRRC), the response rate to chemoradiotherapy is 40%–50%. Additionally, only approximately 40%–50% of patients with recurrent rectal cancer are able to undergo R0 resection. Recent studies in locally advanced rectal cancer (LARC) have shown promising synergistic effects when combining immunotherapy (PD-1/PD-L1 antibodies) with neoadjuvant chemoradiotherapy (nCRT). Therefore, incorporating immunotherapy into the treatment regimen for LRRC patients has the potential to further improve response rates and prognosis. To investigate this, the TORCH-R trial was conducted. This prospective, single-arm, two-cohort, phase II trial focuses on the use of hypofractionated radiotherapy, chemotherapy, and immunotherapy in LRRC patients without or with oligometastases. The trial will include two cohorts: cohort A consists of rectal cancer patients who are treatment-naive for local recurrence, and cohort B includes patients with progressive disease after first-line chemotherapy. Cohort A and cohort B patients will receive 25–40 Gy/5 Fx irradiation or 15–30 Gy/5 Fx reirradiation for pelvic recurrence, respectively. Subsequently, they will undergo 18 weeks of chemotherapy, toripalimab, and stereotactic ablative radiotherapy (SABR) for all metastatic lesions between chemoimmunotherapy cycles. Decisions regarding follow-up of complete response (CR), radical surgery, sustained treatment of non-resection, or exiting the trial are made by a multidisciplinary team (MDT). The primary endpoint of this study is the local objective response rate (ORR). The secondary endpoints include the extrapelvic response rate, duration of response, local recurrence R0 resection rate, progression-free survival (PFS), overall survival (OS), and safety and tolerability. Notably, this trial represents the first clinical exploration of inducing hypofractionated radiotherapy, chemotherapy, and immunotherapy in LRRC patients.Clinical trial registrationhttps://clinicaltrials.gov/study/NCT05628038, identifier NCT05628038.

Combination strategies to improve immunotherapy response in microsatellite stable metastatic colorectal cancer (MSS mCRC) remain an unmet need. Several single-arm clinical trials have shown promising synergistic effects between regorafenib and ICIs; however, some contradictory results have also been reported. Randomized controlled trials are needed to further validate the combination of regorafenib with ICIs. In addition, low-dose radiotherapy has been demonstrated to induce local immune responses by reprogramming the tumor microenvironment when combined with high-dose radiotherapy and ICIs. In this study, we designed a prospective, randomized, controlled phase II trial to investigate the efficacy and safety of regorafenib in combination with high/low-dose radiotherapy plus toripalimab in MSS mCRC compared to regorafenib alone. Patients with MSS metastatic adenocarcinoma of the colon or rectum will be enrolled and randomly assigned into two arms: a control arm and an experimental arm. Patients in the control arm will receive regorafenib monotherapy (120 mg once daily on days 1-21 of each 28 days cycle). Patients in the experimental arm will first receive one cycle of regorafenib (80 mg once daily on days 1-21 of each 28 days cycle) and toripalimab (240mg, q3w), followed by high-dose (4-8 fractions of 8-12Gy) and low-dose (1-10Gy at 0.5-2Gy/fraction) radiotherapy, and then continue regorafenib and toripalimab treatment. The primary endpoint is the objective response rate, and the secondary endpoints are disease control rate, duration of remission, median progress-free survival, median overall survival, and adverse events. Recruitment started in August 2023 and is ongoing.Clinical Trial Registrationhttps://clinicaltrials.gov/study/NCT05963490?cond=NCT05963490&rank=1, identifier NCT05963490.

Abstract Background For patients with locally advanced (T3-4/N +) rectal cancer (LARC), the standard treatment is neoadjuvant chemoradiotherapy combined with total mesorectal resection, which greatly decreases local recurrence but does not improve overall survival. For patients who achieve a complete clinical response (cCR) after nCRT, a “Watch & Wait” (W&W) approach can be received to improve quality of life. Currently, total neoadjuvant therapy (TNT) has been demonstrated to increase the complete response rate and achieve early control of distant metastasis. Recent studies have shown promising synergistic effects of the combination of immunotherapy (PD-1/PD-L1 antibodies) and radiotherapy. Thus, for LARC patients, the combination of immunotherapy and TNT is likely to further improve the rate of complete response and prognosis. The disparities between induction therapy and consolidation therapy need to be investigated. Methods TORCH is a randomized, prospective, multicentre, double-arm, phase II trial of short-course radiotherapy (SCRT) combined with chemotherapy and immunotherapy in LARC. 130 LARC patients will be treated with the TNT approach and assigned to the consolidation arm and induction arm. The consolidation arm will receive SCRT, followed by 6 cycles of capecitabine plus oxaliplatin (CAPOX) and Toripalimab. The induction arm will first receive 2 cycles of CAPOX and Toripalimab, then receive SCRT, followed by 4 cycles of CAPOX and Toripalimab. Both groups will receive curative surgery or the W&W strategy. The primary endpoint is the complete response rate (rate of pCR plus cCR). The secondary endpoints include the grade 3–4 acute adverse effects rate, 3-year disease-free survival (DFS) rate, 3-year local recurrence-free survival (LRFS) rate, 3-year OS rate, rate of surgical complications and quality of life (QoL) scores. The “pick the winner” method is used to investigate the better treatment regimen. The trial was opened on 13th April 2021, and the first patient was recruited on 6th May 2021. Discussion TORCH will investigate whether SCRT combined with chemotherapy and Toripalimab can achieve better complete response rates, good tolerance and prognosis in LARC patients. This is the first clinical trial to compare the efficacy of induced immunotherapy and consolidative immunotherapy based on the TNT strategy. Trial registration Trial Registration Number and Date of Registration: ClinicalTrials.gov NCT04518280 , August 15, 2020.

For locally advanced (T3-4/N+M0) rectal cancer (LARC), neoadjuvant chemoradiotherapy (nCRT) followed by total mesorectal excision (TME) is the standard treatment. It was demonstrated to decrease the local recurrence rate and increase the tumor response grade. However, the distant metastasis remains an unresolved issue. And the demand for anus preservation and better quality of life increases in recent years. Radiotherapy and immunotherapy can be supplement to each other and the combination of the two treatments has a good theoretical basis. Recently, multiple clinical trials are ongoing in terms of the combination of nCRT and immunotherapy in LARC. It was reported that these trials achieved promising short-term efficacy in both MSI-H and MSS rectal cancers, which could further improve the rate of clinical complete response (cCR) and pathological complete response (pCR), so that increase the possibility of ‘Watch and Wait (W&W)’ approach. However, the cCR and pCR is not always consistent, which occurs more frequent when nCRT is combined with immunotherapy. Thus, the efficacy evaluation after neoadjuvant therapy is an important issue for patient selection of W&W approach. Evaluating the cCR accurately needs the combination of multiple traditional examinations, new detective methods, such as PET-CT, ctDNA-MRD and various omics studies. And finding accurate biomarkers can help guide the risk stratification and treatment decisions. And large-scale clinical trials need to be performed in the future to demonstrate the surprising efficacy and to explore the long-term prognosis.