Efficacy of nivolumab as checkpoint inhibitor drug on survival rate of patients with relapsed/refractory classical Hodgkin lymphoma: a meta-analysis of prospective clinical study Abstract Aims The primary standard treatment for classic Hodgkin's lymphoma (cHL) is chemotherapy and radiation therapy. However, some patients get relapsed, or their diseases become resistant. PD1 blocking antibodies have been used to increase the response of treatment in solid tumors, and led to potentially stable responses that are acceptable. Our purpose in this study is to investigate the effect of nivolumab as a PD1 blocking antibody on the survival rate of patients with Hodgkin's cancer. Methods Databases were found in International Medical Sciences, Web of Science, Medline, Scopus, Index Copernicus, PubMed, DOAJ, Google Scholar, EBSCO-CINAHL, and Persian databases containing SID and Magiran using keywords such as: “checkpoint inhibitor”, “nivolumab”, “Hodgkin lymphoma”, and “PD1 Blockade”. The risk of bias was determined by two external observers using the Cochrane checklists. After the search, the data provided in 51 documents was independently evaluated. Duplicate papers were excluded. Assessing the full texts of the remaining papers, 7 papers were approved. Results Pooled data of these seven studies revealed that the overall objective response rate was 68% (CI 64.1% to 72.1%; heterogeneity; I2 = 40.19%; p = 0.123) with partial remission (52%; CI 46.5% to 57.6%; heterogeneity; I2 = 28.36%; p = 0.212). In the pooled analysis, complete remission was 16.8 (CI 11.1% to 26.4%). Pooled data of six studies showed that stable disease was averaged to 19% (CI 16% to 23%; heterogeneity; I2 = 30%; p = 0.209; fixed-effect model). Conclusions The results of the study indicate that nivolumab as a PD1 pathway inhibitor can be effective in treating relapsed and refractory cHL patients compared to other therapies, and lead to more effective treatment over the long term. Furthermore, the adverse effects of nivolumab are controllable and have a good safety profile.