The risks of hematological toxicities of nivolumab in cancer patients: A PRISMA-compliant meta-analysis

Background: Nivolumab is the human programmed cell death-1 (PD-1)-blocking antibody showing significant effect in many refractory cancers. However, little is known about its risks of hematological toxicities, rare but clinically serious and potentially life-threatening adverse events. We want to explore whether nivolumab can increase the risks of hematological toxicities compared with other immunotherapy or chemotherapy drugs. Method: The databases of PubMed, Embase, Web of science, and CNKI were searched. We used the medical subject heading terms “Nivolumab” plus keyword “Nivolumab” to search studies published from August 1990 to October 2021. For the included articles, we calculated the relative risks and the corresponding 95% confidence intervals (CIs) for the risks of anemia, neutropenia, and leukopenia in patients treated with nivolumab versus control drugs. Results: Five original articles on the nivolumab trials were identified with 2399 patients enrolled in this meta-analysis. The relative risks of anemia, neutropenia, and leukopenia were 0.343 (95% CI: 0.177–0.663; P = .001), 0.020 (95% CI: 0.008–0.053; P = .000), and 0.054 (95% CI: 0.015–0.191; P = .000), respectively. Conclusion: The PD-1 inhibitor-nivolumab did not increase the risk of anemia, neutropenia and leukopenia. It may enhance awareness about lower risks of hematological toxicities when choosing nivolumab as PD-1 inhibitor among clinicians.