The impact of the conditioning intensity and TBI on acute GVHD (aGVHD) is still a matter of debate. We analyzed 6848 adult recipients who received allogeneic hematopoietic cell transplants (HCT) between 2006 and 2011 in Japan. The subjects were divided into groups who had received myeloablative conditioning (MAC) or reduced-intensity conditioning (RIC), either with or without TBI. There was a significant difference in the incidence of aGVHD 2–4 among the different conditioning types: 39% in TBI-MAC, 35% in TBI-RIC and 32% in both no-TBI MAC and no-TBI-RIC (P<0.001). In a multivariate analysis, TBI-MAC, but not no-TBI MAC, was significantly associated with an increased risk of aGVHD 2–4 (hazard ratio (HR) 1.33, P<0.01), whereas TBI-RIC was associated with an increased risk of GVHD 3–4 (HR 1.36, P=0.048). TBI-MAC and TBI-RIC were significantly associated with skin and gastrointestinal aGVHD. Subgroup analyses demonstrated that not only TBI-MAC, but also TBI-RIC, was significantly associated with aGVHD 2–4 in older patients. Furthermore, high-dose TBI only had an adverse impact on aGVHD 2–4 in HLA-matched HCT. Impacts of intensity and TBI on aGVHD differ by patient backgrounds, and this difference should be considered to establish a risk-adapted strategy for the prevention of aGVHD.

Cryptogenic organizing pneumonia (COP), previously known as bronchiolitis obliterans organizing pneumonia (BOOP), is a significant complication after allogeneic hematopoietic SCT (HCT). However, the pathogenesis of this complication has not yet been elucidated. Therefore, we identified the pre-transplant risk factors for the development of COP/BOOP using the Japan transplant registry database between 2005 and 2009. Among 9550 eligible recipients, 193 experienced COP/BOOP (2%). HLA disparity (odds ratio (OR) 1.51, P=0.05), female-to-male HCT (OR 1.53, P=0.023), and PBSC transplant (OR 1.84, P=0.0076) were significantly associated with an increased risk of COP/BOOP. On the other hand, BU-based myeloablative conditioning (OR 0.52, P=0.033), or fludarabine-based reduced-intensity conditioning (OR 0.50, P=0.0011) in comparison with a TBI-based regimen and in vivo T-cell depletion (OR 0.46, P=0.055) were associated with a lower risk. Of the 193 patients with COP/BOOP, 77 died, including non-relapse death in 46 (59%). Pulmonary failure and fatal infection accounted for 41% (n=19) and 26% (n=12) of the non-relapse death. Allogeneic immunity and conditioning toxicity could be associated with COP/BOOP. Prospective studies are required to elucidate the true risk factors for COP/BOOP and to develop a prophylactic approach.

Cytomegalovirus reactivation (CMVR) after allogeneic hematopoietic cell transplantation (HCT) is a frequent complication related to survival outcomes; however, its impact on relapse remains unclear, especially in acute lymphoblastic leukemia (ALL). In this nationwide retrospective study, we included patients with acute myeloid leukemia (AML) and ALL in the first or second complete remission who underwent their first HCT using a pre-emptive strategy for CMVR. Because 90% of cases with CMVR had occurred by day 64 and 90% of cases with grades 2 to 4 acute graft-versus-host disease (GVHD) had occurred by day 58, a landmark point was set at day 65. In landmark analyses, 3793 patients with AML and 2213 patients with ALL who survived without relapse for at least 65 days were analyzed. Multivariate analyses showed that CMVR was associated with a lower incidence of relapse in both AML (hazard ratio [HR], 0.81; 95% confidence interval [CI], 0.69-0.95; P = .009) and ALL (HR, 0.81; 95% CI, 0.66-0.99; P = .045). These findings were confirmed when CMVR was used as the time-dependent covariate. Moreover, our study suggests that the protective effect of CMVR on relapse was independent of acute GVHD. A post-hoc subgroup analysis of combined AML and ALL showed that CMVR had a mild antileukemia effect without effect modification, in contrast to the impact of CMVR on NRM. Our findings may provide important implications for strategies used for CMV prophylaxis after HCT.

A preemptive strategy has successfully decreased cytomegalovirus (CMV) disease after allogeneic hematopoietic cell transplantation (HCT). However, some recipients still develop CMV gastroenteritis, especially after acute graft-versus-host disease (aGVHD), and its incidence, risk factors, and prognostic impact remain to be elucidated. We retrospectively analyzed 3759 consecutive adult patients who developed grade II-IV aGVHD using a Japanese registry database. The cumulative incidence of CMV gastroenteritis was 5.7% by day 365 from the development of grade II-IV aGVHD. Advanced age (hazard ratio [HR], 1.60; 95% confidence interval [CI], 1.16-2.22; P = .004), GVHD prophylaxis with mycophenolate mofetil and calcineurin inhibitor (HR, 1.73; 95% CI, 1.08-2.77; P = .024), lower-gut aGVHD (HR, 2.17; 95% CI, 1.58-2.98; P < .001), and the use of systemic steroids (HR, 1.78; 95% CI, 1.16-2.74; P = .008) were independent risk factors for CMV gastroenteritis. Development of CMV gastroenteritis was associated with an increased risk of nonrelapse mortality (HR, 1.89; 95% CI, 1.50-2.39; P < .001). Moreover, letermovir prophylaxis significantly reduced both the incidence of CMV gastroenteritis (HR, 0.50; 95% CI, 0.25-0.99; P = .047) and the risk of nonrelapse mortality (HR, 0.72; 95% CI, 0.52-0.99; P = .043). In summary, CMV gastroenteritis is a life-threatening complication that sets the need for preventive strategies with letermovir and targeted surveillance.

The impact of hepatitis C virus (HCV) infection on outcomes following allogeneic hematopoietic cell transplantation (HCT) remains a matter of debate. We have retrospectively examined the significance of HCV infection among recipients who received allogeneic HCT, using a Japan transplant outcome registry database between 2006 and 2009. Among 7,831 recipients, 136 were HCV‐positive. The rate of hematopoietic recovery was lower in the HCV‐positive group (neutrophil recovery of 500 × 10⁶/L or higher: 79% vs. 87% at Day 30, P = 0.087; platelet recovery of 50 × 10⁹/L or higher: 57% vs. 65% at Day 60, P = 0.012). The HCV‐positive group had a significantly higher incidence of nonrelapse mortality 38% vs. 25% at 2 years, P < 0.01) and inferior overall survival (41% vs. 51% at 2 years, P < 0.01). A multivariate analysis revealed that HCV seropositivity was associated with an independent risk for higher nonrelapse mortality (hazard ratio: 1.65, P < 0.01) and inferior overall survival (hazard ratio: 1.39, P < 0.01). The incidences of death due to hepatic problems (8% vs. 2%, P < 0.01), bacterial infection (10% vs. 4%, P < 0.01), or graft failure (5% vs. 2%, P = 0.084) tended to be higher in the HCV‐positive group. HCV infection had an adverse impact on the clinical outcome following HCT, especially in the setting of unrelated transplantation. Careful evaluation before embarking on HCT and intensive assessment against complications are warranted in HCV‐infected recipients. Am. J. Hematol. 88:477–484, 2013.