Phase I SBRT combined with AK104 treatment Target area and dose of SBRT: Select a relapsed or metastatic lymph node or lesion that has little effect on surrounding normal tissues and has not been irradiated before, and then perform radiation therapy with a total dose of 24-50Gy/8-12.5Gy/3-4f per lesion (the specific target area and dose range will be decided by the treating physician). AK104 is administered within one week after SBRT, and the regimen for AK104 is 10 mg/kg as a single dose. If multiple target lesions are treated with SBRT, multiple cycles of 21 days each are possible. When patients are treated with multiple courses of radiotherapy, it is difficult to ensure the accuracy of the overlapping doses of the re-course of radiotherapy, and the cumulative dose of organs at risk (OAR) is evaluated using the deformable image registration (DIR) technique.~Phase II AK104 monotherapy maintenance phase Monotherapy maintenance with AK104 10 mg/kg every 21 days until progression, up to one year if no progression. Patients were enrolled in Phase I and Phase II for a minimum of three cycles.~In addition, 10 mL of peripheral blood was drawn from patients before each cycle of treatment and analyzed by flow cytometry for lymphocyte subpopulation. And the changes of HMGB1 and cytokines IL-8, IL-6, IL-12, IFN-α, IFN-β, IL-2, IL-4, IL-5, INF-γ, TNF-α, IL-10, TGF-β were detected by ELISA test. By testing the above indicators, they are used to respond to the immune status after treatment as well as to screen for valid indicators that can be used to assess efficacy.~Throughout the study period, the assessment should be performed as much as possible according to the imaging assessment plan time points specified in the protocol. Tumor imaging assessments will be performed every 6 weeks during the first phase of treatment and every 9 weeks during the second phase of treatment. This project used velosity software to perform clinical tumor imaging assessment according to RECIST 1.1 criteria and irRECIST and iRECIST criteria assessment every 6 weeks; NCI-CTCAE 5.0 was used for safety assessment and adverse events were recorded throughout the study until 30 days after the end of treatment.~After the end of treatment, all subjects will be followed for survival every 3 months until death, loss to follow-up, withdrawal of knowledge, or the sponsor's decision to terminate the study.
The entire treatment process is divided into two phases: Phase I SBRT combined with PD-1/CTLA-4 bispecific antibody (AK104) and Phase II AK104 single-agent maintenance therapy.