PD-1 Inhibitors Combined With VEGF Inhibitors for Locally Advanced dMMR/MSI-H Colorectal Cancer

This is an open-label phase II study, with the aim of determining the efficacy of PD-1 inhibitors (Camrelizumab) plus VEGF inhibitor (Apatinib) as a neoadjuvant therapy for dMMR/MSI-H locally advanced colorectal cancer. Patients will be evaluated for eligibility within 14 days prior to study initiation with CT (for colon cancer) and/or MRI (for rectal cancer). Patients will be given four cycles of Camrelizumab (200mg iv every 3 weeks) plus Apatinib (250mg QD day1-14) before being evaluated for response. For patients with colon cancer, if a SD/PD is achieved and the tumor is deemed unresectable, they will be offered chemotherapy±radiotherapy, while if a CR or PR is achieved, they will be offered another four cycles of Camrelizumab + Apatinib. After completing 8 cycles of treatment, if a CR is achieved they will be offered the choice of Watch \& Wait. For patients with rectal cancer who have a SD/PD (after 4 cycles), chemoradiotherapy will be offered, while for those with a CR/PR, another four cycles of the treatment will be given. After completing 8 cycles of treatment, if a CR is achieved patients will be offered the choice of Watch \& Wait.