Efficacy and safety of camrelizumab plus apatinib compared to apatinib monotherapy as third-line or above therapy for metastatic colorectal cancer patients: A retrospective cohort study

What Is Known and Objective: Programmed cell death protein-1 (PD-1) inhibitors synergize apatinib for anti-tumour effect by regulating tumour microenvironment, vascular endothelial growth factor, hypoxia condition, immune response, etc. This study aimed to investigate the treatment efficacy and safety of camrelizumab (PD-1 inhibitor) plus apatinib as third-line or above therapy in metastatic colorectal cancer (mCRC) patients. Methods: Totally, 64 unresectable mCRC patients receiving camrelizumab plus apatinib (N = 31) and apatinib (N = 33) were retrospectively enrolled. Results: Disease control rate (80.6% vs. 57.6%) (P = 0.047) was elevated in camrelizumab plus apatinib group compared to apatinib group; however, objective response rate (22.6% vs. 6.1%) (P = 0.078) only showed an increasing trend but did not achieve statistical significance. Besides, the median (95% confidence interval [CI]) progressive-free survival (PFS) and overall survival (OS) were 6.9 (3.7-10.1) and 11.5 (7.7-15.3) months in camrelizumab plus apatinib group; meanwhile, the median (95% CI) PFS and OS were 3.6 (1.7-5.5) and 6.7 (5.0-8.4) months in the apatinib group. Additionally, PFS (P = 0.017) and OS (P = 0.006) were prolonged in camrelizumab plus apatinib group compared with apatinib group, which was confirmed by further multivariate Cox's proportional hazards regression analysis (hazard ratio [HR] = 0.340, P < 0.001 for PFS; HR = 0.271, P < 0.001 for OS). The incidence of total, grade 1-2, and grade 3-4 adverse events did not differ between groups (all P > 0.05). Conclusion: Camrelizumab (PD-1 inhibitor) plus apatinib achieves a better treatment efficacy than apatinib as third-line or above therapy with a good safety profile in mCRC patients.