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Investigators are using checkpoint inhibitors (CPIs) to treat aggressive hematologic malignancies in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) and in some patients with relapsed disease after allo-HSCT. CTLA-4 inhibitors and PD-1 inhibitors are 2 main types of CPIs, which work through activation of the immune system. On one hand, CPIs can achieve graft-versus-tumor effect, and on the other hand, there is a risk of graft-versus-host disease (GVHD). After a comprehensive literature review, we included data (n = 283) from 24 studies (11 original manuscripts and 13 case reports or case series) and evaluated the results to assess the safety and efficacy of CPI use in conjunction with allo-HSCT. Among the 283 patients, 107 received CPI before allo-HSCT, and 176 received CPI after allo-HSCT. The most common indication for CPI use was for Hodgkin lymphoma. The CPIs used in various studies included ipilimumab, nivolumab, and pembrolizumab. Among the patients exposed to CPI before allo-HSCT, 56% developed acute GVHD and 29% developed chronic GVHD. Investigators reported 20 deaths, 60% of which were GVHD-related. The overall mortality risk with GVHD is 11%. In this group, investigators noted an objective response rate (ORR) in 68% of patients, with complete remission (CR) in 47%, partial remission (PR) in 21%, and stable disease in 11%. Among the patients who received a CPI after allo-HSCT for disease relapse, 14% developed acute GVHD and 9% developed chronic GVHD. Investigators reported 40 deaths, 28% of which were GVHD-related. The mortality risk with GVHD is approximately 7%. Investigators reported ORR in 54% of patients, with CR in 33%, PR in 21%, and disease stabilization in 5%. After careful evaluation of collective data, we found that CPI use both before and after allo-HSCT can be highly effective, but exposure can lead to a significantly increased risk of GVHD-related morbidity and mortality in this patient population. Despite limited availability of data, there is need for extreme caution while making decisions regarding the use of CPIs. Detailed discussions and prospective well-designed clinical trials are needed to explore this issue further., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Patients undergoing allogenic hematopoietic stem cell transplantation (allo-HSCT) are at a very high risk of hepatitis B virus reactivation (HBVr). Lamivudine is commonly used as prophylaxis against HBVr in high-risk patients undergoing allo-HSCT. Unfortunately, its efficacy is diminishing due to the development of HBV mutant drug-resistant strains. With the availability of newer antiviral agents such as entecavir, telbivudine, adefovir, and tenofovir, it is important to assess their role in HBVr prophylaxis. A comprehensive search of 7 databases was performed to evaluate efficacy of antiviral prophylaxis against HBVr in allo-HSCT patients (PubMed/Medline, Embase, Scopus, Cochrane Library, Web of Science, CINAHL, and ClinicalTrials.gov (June 21, 2017)). We identified 10 studies, with 2067 patients undergoing allo-HSCT; these primarily evaluated the use of lamivudine and entecavir as prophylaxis against HBVr in patients undergoing allo-HSCT because there were little or no data about adefovir, telbivudine, or tenofovir as prophylaxis in this specific patient population. Thus, included studies were categorized into 2 main prophylaxis groups: lamivudine and entecavir. Results of our meta-analysis suggest that entecavir is very effective against HBVr, although further clinical trials are required to test efficacy of new antivirals and explore the emerging threat of drug resistance., (Copyright © 2018 The American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.)