Secondary failure of platelet recovery (SFPR), a late decrease in the platelet count after primary platelet recovery that is not due to relapse or graft rejection, occasionally occurs after allogeneic hematopoietic stem cell transplantation (HSCT). The risk factors and impact of SFPR on transplantation outcomes are not well known in the clinical setting. Therefore, we retrospectively evaluated 184 adult patients who underwent their first allogeneic HSCT and achieved primary platelet recovery. The cumulative incidence of SFPR, defined as a decrease in the platelet count to below 20,000/µL for more than 7 days, was 12.2% at 3 years, with a median onset of 81 days (range, 39 to 729) after HSCT. Among patients who developed SFPR (n = 23), 19 (82.6%) showed recovery to a sustained platelet count of more than 20,000/µL without transfusion support, and the median duration of SFPR was 23 days (range, 7 to 1048 days). A multivariate analysis showed that in vivo T cell depletion (hazard ratio [HR], 6.92; 95% confidence interval [CI], 2.31 to 20.7; P < .001), grades II to IV acute graft-versus-host disease (HR, 3.99; 95% CI, 1.52 to 10.5; P = .005), and the use of ganciclovir or valganciclovir (HR, 2.86; 95% CI, 1.05 to 7.77; P = .039) were associated with an increased risk for SFPR. The occurrence of SFPR as a time-dependent covariate was significantly associated with inferior overall survival (HR, 2.29; 95% CI, 1.18 to 4.46; P = .015) in a multivariate analysis. These findings may help to improve the management and treatment strategy for SFPR.

Limited data are available on prophylaxis for herpes simplex virus (HSV) and varicella zoster virus (VZV) disease following autologous hematopoietic stem cell transplantation (auto-HCT). We retrospectively reviewed the clinical charts of 105 consecutive patients who underwent their first auto-HCT at our institution between September 2007 and June 2014. Before August 2009, 30 patients received oral acyclovir at 1000 mg/day until engraftment, whereas after September 2009, 69 patients received oral acyclovir at 200 mg/day. After engraftment, acyclovir was continued at 200 mg/day at the discretion of the attending physicians in both groups. The cumulative incidence of HSV disease at 1 year after auto-HCT was 7.7 and 4.5 % in patients who received oral acyclovir at 1000 and 200 mg/day, respectively (P = 0.75). Patients were next divided into three groups according to the timing at which acyclovir prophylaxis was stopped after auto-HCT; at engraftment, between engraftment and 1 year after auto-HCT, and later than 1 year. The cumulative incidence of VZV disease was 25.8, 7.7, and 0.0 % at 1 year, respectively. This study suggests that low-dose acyclovir prophylaxis may be effective for preventing HSV and VZV disease after auto-HCT. Our findings support the recommendation of acyclovir prophylaxis within the first year after auto-HCT.

Aplastic anemia patients who received rabbit antithymocyte globulin exhibited response and survival rates inferior to those who received horse antithymocyte globulin in several studies. Therefore, we conducted a meta-analysis to compare rabbit and horse antithymocyte globulin as immunosuppressive therapy for aplastic anemia. We searched online databases for studies that compared antithymocyte globulin regimens as first-line treatment for aplastic anemia, including both randomized and non-randomized controlled trials. The early mortality rate at 3 months and overall response rate at 6 months were evaluated. Thirteen studies were included in the analysis. The risk ratio (RR) of early mortality for rabbit vs. horse antithymocyte globulin was 1.33 [95% confidence interval (CI) 0.69-2.57; P = 0.39], with significant heterogeneity. A sensitivity analysis suggested higher early mortality rate in patients who received rabbit antithymocyte globulin. The overall response rate was significantly higher in patients who received horse antithymocyte globulin (RR 1.27; 95% CI 1.05-1.54; P = 0.015). In conclusion, in aplastic anemia patients treated with ATG, early mortality rate was not significantly different in patients receiving horse or rabbit ATG, although a sensitivity analysis showed higher early mortality in the rabbit ATG group. Horse ATG was associated with significantly higher response rate than rabbit ATG.

Delayed platelet recovery (DPR) despite prompt neutrophil engraftment is frequently observed after allogeneic hematopoietic stem cell transplantation (HSCT). However, few studies have evaluated the risk factors and long-term outcome. Therefore, we retrospectively analysed 219 adult patients who underwent their first allogenic HSCT with neutrophil engraftment. Of these 219 patients, 50 (22.8%) had DPR that was defined as relapse-free survival at day 60 after HSCT without primary platelet recovery despite neutrophil engraftment. The results of a multivariate analysis showed that a high-risk underlying disease (odds ratio [OR], 2.38; 95% confidence interval [CI], 1.04-5.48; P = .041) and human leukocyte antigen-mismatched HSCT (OR, 2.63; 95% CI, 1.28-5.43; P = .009) were associated with an increased risk of DPR. In univariate analyses, the occurrence of DPR was significantly associated with inferior overall survival, high nonrelapse mortality, and a low incidence of chronic graft-versus-host disease (GVHD), despite a comparable relapse rate. In multivariate analyses, DPR was associated with inferior overall survival (hazard ratio [HR], 2.00; 95% CI, 1.23-3.27; P = .005) and a low incidence of chronic GVHD (HR, 0.42; 95% CI, 0.22-0.78; P = .002). In conclusion, DPR was a strong predictor of shorter survival but also less frequent chronic GVHD.

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