Cryoablation Combined With Tirelizumab and Bevacizumab in Liver Metastatic TNBC Patients Failed by Multiline Therapy

This is a prospective, single-arm, single-center phase II clinical trial in liver metastatic triple-negative breast cancer patients failed by multiline therapy. All subjects will receive cryoablation combined with tirelizumab + bevacizumab: 1. Cryoablation of liver metastases: Cryoablation of 1-2 typical metastatic lesions will be performed on D1 under general anesthesia and ultrasound guidance for two cycles. If the patient has no measurable lesions outside the liver, the measurable lesions should be retained after partial ablation of the liver lesions. 2. PD-1 antibody + anti vascular therapy: patients will receive 200mg Tirelizumab ( IV Q3W) + Bevacizumab 7.5mg/kg ( IV Q3W) at D14 after cryoablation until there is disease progression, intolerable toxic reaction, subject withdraws informed consent or the study ends (whichever comes first). 3. Puncture biopsy of liver metastases will completed 1-3 days before cryoablation, 1-3 days before the first treatment with tirelizumab + bevacizumab, 2 cycles after treatment with tirelizumab + bevacizumab and after disease progression, and blood samples (about 10ml) were collected for mutation load detection and immune function evaluation.