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.
Ability to understand and willingness to sign a written informed consent form.
Age 18-80 years, male or female.
Histologically confirmed microsatellite stable (MSS) / proficient mismatch repair (pMMR) colorectal adenocarcinoma.
Failure after first-line triplet chemotherapy containing platinum and irinotecan; Or failure after first-line platinum-based chemotherapy followed by second-line irinotecan-based chemotherapy.
History of severe hypersensitivity to monoclonal antibodies or anti-angiogenic agents.
Prior exposure to immune checkpoint inhibitors (including anti-PD-1, anti-PD-L1, anti-CTLA-4 antibodies), immune checkpoint agonists (e.g., targeting ICOS, CD40, CD137, GITR, OX40), or any prior cancer immunotherapy.
Active autoimmune disease or history of autoimmune disease, including but not limited to interstitial pneumonitis, colitis, hepatitis, hypophysitis, vasculitis, nephritis, hyperthyroidism, or hypothyroidism (patients on stable hormone replacement therapy may be eligible). Patients with psoriasis or childhood asthma/allergy that has completely resolved and requires no adult intervention may be eligible; patients requiring bronchodilator therapy are excluded.
History of immunodeficiency, including positive HIV test, congenital or acquired immunodeficiency, prior organ transplantation, or allogeneic bone marrow transplantation.
Single group
High- and Low-Dose Radiotherapy
RadiationParticipants will receive a stratified high- and low-dose radiotherapy regimen to metastatic lesions based on lesion size, followed by sequential anti-angiogenic tyrosine kinase inhibitor (TKI) and anti-PD-1 antibody therapy. Metastatic lesions with a maximum diameter ≤2 cm will be treated with stereotactic body radiotherapy (SBRT) at 8 Gy per fraction for 3 consecutive fractions (total dose 24 Gy) prior to initiation of the first cycle of targeted and immunotherapy. The total cumulative volume of lesions treated with SBRT will not exceed 100 cm². Metastatic lesions with a maximum diameter \>2 cm will receive low-dose radiotherapy (LDRT) at 3 Gy per fraction for 5 fractions. LDRT will be administered rhythmically, with one fraction delivered prior to each cycle of targeted and immunotherapy, for a total of five fractions. The total cumulative volume of lesions treated with LDRT will not exceed 500 cm². Within 7 days after completion of radiotherapy, participants will initiate systemi
Anti-Angiogenic TKI and Anti-PD-1 Therapy
DrugParticipants will receive systemic therapy consisting of an oral anti-angiogenic tyrosine kinase inhibitor (TKI) in combination with an intravenous anti-PD-1 monoclonal antibody. The anti-angiogenic TKI will be administered orally according to the approved dosing schedule. The anti-PD-1 antibody will be administered intravenously at standard dosing intervals. Treatment will begin within 7 days after completion of radiotherapy and will continue until disease progression, unacceptable toxicity, withdrawal of consent, or investigator decision. Safety will be monitored throughout treatment, and adverse events will be graded according to CTCAE version 5.0.
Objective Response Rate (ORR)
Disease Control Rate (DCR)
Disease Control Rate is defined as the proportion of participants achieving Complete Response (CR), Partial Response (PR), or Stable Disease (SD) according to RECIST version 1.1.
Progression-Free Survival (PFS)
Overall Survival (OS)
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