SBRT-LDRT-Cadonilimab for Advanced Gastric, Colorectal and Ovarian Cancers With Peritoneal Metastases

Several studies have confirmed that the prognosis for advanced solid tumors for which there is no longer a standard of care is extremely poor, with optimal supportive care and an overall survival time of usually 1-5 months, and better treatment options are urgently needed to benefit patients' survival. For advanced solid tumors with peritoneal metastases, the prognosis is even worse. The peritoneal metastatic lesions respond poorly to chemotherapy, targeting, immunotherapy, surgical treatment, and other currently used treatments, and the expected survival time is short, so there is an urgent need to seek more effective treatment modalities. There is a synergistic effect between radiotherapy and immunotherapy, and several studies have explored the combination of radiotherapy and immune checkpoint inhibitors in the treatment of solid tumors, and the results have shown that this combination regimen has a good anti-tumor effect, but the optimal radiotherapy modality and dose of radiotherapy are still in the exploratory stage. At present, some preclinical studies and small sample studies have shown that the combination of high- and low-dose radiotherapy can change the tumor immune microenvironment, reverse the state of immunosuppression, and play a strong anti-tumor effect in combination with immune checkpoint inhibitors. Therefore, the investigators propose to conduct a single-arm, prospective clinical study of whole-abdominal low-dose radiotherapy (LDRT) combined with stereotactic body radiation therapy (SBRT) followed by Cadonilimab for the treatment of advanced gastric, colorectal, and ovarian cancers with peritoneal metastases. The study evaluates the efficacy of this combination therapy modality on peritoneal metastatic lesions, as well as the objective remission rate (ORR), disease control rate (DCR), duration of remission (DoR), progression-free survival (PFS), overall survival (OS), and safety of the patients. Our study aims to further explore the combination treatment options to improve the efficacy and prognosis of backline treatment for advanced tumors, and to provide more evidence for the clinical practice of radiotherapy combined with immunotherapy in advanced gastric, colorectal, and ovarian cancers with peritoneal metastases.