Radiotherapy-Induced Immune Priming

To explore the efficacy and toxicity of spatially fractionated radiotherapy in the treatment of tumors.

To learn if low doses of radiation therapy can help the drug elranatamab enhance the killing effect of the cancer cells.

The goal of this clinical trial is to learn whether a high- and low-dose radiotherapy regimen followed by anti-angiogenic TKI and anti-PD-1 antibody therapy works to treat advanced metastatic colorectal cancer. It will also evaluate long-term survival outcomes and explore potential biomarkers associated with tumor response and immune modulation. The main questions it aims to answer are: Does the high- and low-dose radiotherapy regimen followed by sequential anti-angiogenic TKI and anti-PD-1 therapy improve the objective response rate (ORR) in patients with advanced metastatic colorectal cancer? What are the disease control rate (DCR) and survival outcomes following this treatment strategy? Are tumor response and long-term survival associated with specific biomarkers related to systemic immune modulation induced by radiotherapy to different metastatic organs? How does this radiotherapy pattern affect tumor immune infiltration in metastatic lesions? This is a single-arm, single-center, prospective Phase II clinical study designed to evaluate the efficacy of a high- and low-dose radiotherapy regimen targeting metastatic lesions followed by sequential anti-angiogenic TKI and anti-PD-1 antibody therapy in patients with advanced metastatic colorectal cancer. Participants will: Receive high- and low-dose radiotherapy to metastatic lesions. Subsequently receive anti-angiogenic TKI combined with anti-PD-1 antibody therapy. Undergo regular clinical assessments and imaging evaluations to determine tumor response. Provide blood and tumor samples for biomarker and immune infiltration analysis. Be followed for survival outcomes and disease progression.