The use of venetoclax-based salvage therapy for post-hematopoietic cell transplantation relapse of acute myeloid leukemia

For patients with high risk myeloid disease, allogeneic hematopoietic cell transplantation (HCT) is the only potentially curative therapy. Unfortunately, many of these patients relapse after HCT and have a limited survival. The recent approval of venetoclax, an orally bioavailable BCL-2 inhibitor, resulted in significant responses in treatment naïve acute myeloid leukemia (AML), and off-label use in the relapsed/refractory setting is increasing. We report the outcomes of 21 patients who underwent allogeneic HCT for myeloid disease, relapsed with AML, and were treated with venetoclax. Several patients had poor risk features including antecedent hematologic malignancy (6/21), complex karyotype (6/21), and TP53 mutations (5/21). The median age was 64.5 years and time from HCT to relapse was 5.7 months (range: 0.9 to 44.9 months). Of the 19 patients who were assessed for response, there were meaningful treatment responses seen in eight patients: five CR, three CRi, zero PR, for an ORR of 42.1%. Treatment effect was seen in six additional patients, including four in the morphologic leukemia-free state. Nine patients maintained their response for ≥3 months and eight were receiving therapy at data cut. Post-HCT AML relapse has an exceedingly poor outcome, and venetoclax-based therapy is a potent therapy option that should be studied prospectively in this setting.     

Optimizing Antithymocyte Globulin Dosing for Unrelated Donor Allogeneic Hematopoietic Cell Transplantation Based on Recipient Absolute Lymphocyte Count

Antithymocyte globulin (ATG) is used as prophylaxis against graft-versus-host disease (GVHD). Current dosing regimens for ATG are empiric and weight-based, and do not account for patient-specific factors. Furthermore, the target of ATG, recipient T cells post-cytotoxic chemotherapy, is not a function of recipient weight. We hypothesized the recipient peripheral blood absolute lymphocyte count (ALC) on the day of ATG administration would interact with the dose of ATG administered to predict transplantation outcomes. We retrospectively analyzed 135 patients who received ATG for GVHD prophylaxis for unrelated allogeneic hematopoietic cell transplantation at 3 different doses: 10?mg/kg, 7.5?mg/kg, and 5?mg/kg. There was no difference in 2-year overall survival (OS) among ATG dosing groups; however, deaths from infectious complications were significantly higher with higher doses of ATG (3.7% versus 19% versus 26.7%; P?=?.02). Severity of chronic GVHD was lower with higher doses of ATG (28% versus 24% versus 4%; P?=?.03). In multivariate analysis, the median peripheral blood ALC on day of ATG administration and the total amount of ATG interacted to predict OS (hazard ratio, .09; P?=?.03). For low recipient ALC (10th percentile, or .56 × 10²/µL), a higher total ATG dose was associated with a greater risk of death, whereas for high recipient ALC (90th percentile, or 24.96 × 10²/µL), a higher ATG dose was associated with a lower risk of death. Our findings suggest that the interaction between ATG and its target, the recipient lymphocyte, could represent a new paradigm for ATG dosing.     

Transplant Outcomes for Secondary Acute Myeloid Leukemia: Acute Leukemia Working Party of the European Society for Blood and Bone Marrow Transplantation Study

Secondary acute myeloid leukemia (sAML) has been associated with inferior outcomes compared with de novo AML. Little is known about patient risk factors and outcomes in sAML after allogeneic hematopoietic stem cell transplantation (HCT); thus, this large systemic analysis of the European Society for Blood and Bone Marrow Transplantation registry was performed. This study included 4997 patients with sAML who received HCT from 2000 to 2016. In univariate analysis the 2-year cumulative incidence of chronic graft-versus-host disease (GVHD), relapse, and nonrelapse mortality (NRM) were 33.5% (95% confidence interval [CI], 32% to 34.9%), 33.7% (95% CI, 32.3% to 35.1%), and 27.5% (95% CI, 26.1% to 28.7%), respectively. Overall survival (OS), leukemia-free survival (LFS), and GVHD-free, relapse-free survival (GRFS) at 2 years were 44.5% (95% CI, 43% to 46%), 38.8% (95% CI, 37.4% to 40.3%), and 27.2% (95% CI, 25.9% to 28.6%), respectively. In multivariate analysis, patients receiving myeloablative regimens had decreased relapse (hazard ratio, .859; 95% CI, .761 to .97; P?=?.01), higher NRM (hazard ratio, 1.175; 95% CI, 1.03 to 1.341; P?=?.02), and no differences in OS, LFS, and GRFS compared with patients receiving reduced-intensity conditioning regimens. Active disease, adverse cytogenetics, older age, Karnofsky performance status (≤80%), ex vivo T cell depletion, other malignant hematologic diseases, and patient cytomegalovirus seropositivity were associated with inferior OS and LFS. These variables should be considered in patients with sAML in need of HCT, and further study regarding the impact of conditioning regimens on relapse is needed.     

Reduced intensity conditioning allogeneic hematopoietic cell transplantation for adult acute myeloid leukemia in complete remission - a review from the Acute Leukemia Working Party of the EBMT

Acute myeloid leukemia is the most common indication for an allogeneic hematopoietic cell transplant. The introduction of reduced intensity conditioning has expanded the recipient pool for transplantation, which has importantly made transplant an option for the more commonly affected older age groups. Reduced intensity conditioning allogeneic transplantation is currently the standard of care for patients with intermediate or high-risk acute myeloid leukemia and is now most often employed in older patients and those with medical comorbidities. Despite being curative for a significant proportion of patients, post-transplant relapse remains a challenge in the reduced intensity conditioning setting. Herein we discuss the studies that demonstrate the feasibility of reduced intensity conditioning allogeneic transplants, compare the outcomes of reduced intensity conditioning versus chemotherapy and conventional myeloablative conditioning regimens, describe the optimal donor and stem cell source, and consider the impact of post-remission consolidation, comorbidities, center experience, and more intensive (reduced toxicity conditioning) regimens on outcomes. Additionally, we discuss the need for further prospective studies to optimize transplant outcomes.     

Time to explore preventive and novel therapies for bronchiolitis obliterans syndrome after allogeneic hematopoietic stem cell transplantation

Although allogeneic hematopoietic stem cell transplant (allo-HSCT) is performed to treat otherwise incurable and fatal diseases, transplantation itself can lead to life-threatening complications due to organ damage. Pulmonary complications remain a significant barrier to the success of allo-HSCT. Lung injury, a frequent complication after allo-HSCT, and noninfectious pulmonary deaths account for a significant proportion of non-relapse mortality. Bronchiolitis obliterans syndrome (BOS) is a common and potentially devastating complication. BOS is now considered a diagnostic criterion of chronic graft-versus-host-disease (cGVHD), and National Institutes of Health (NIH) consensus has been published to establish guidelines for diagnosis and monitoring of BOS. It usually occurs within the first 2 years but may develop as late as 5 years after transplantation. Recent prevalence estimates suggest that BOS is likely underdiagnosed, and when severe BOS does occur, current treatments have been largely ineffective. Prevention and effective novel approaches remain the primary tools in the clinician's arsenal in managing BOS. This article provides an overview of the currently available and novel strategies for BOS, and we also discuss specific preventive interventions to reduce severe BOS after allo-HSCT. Therapeutic trials continue to be needed for this orphan disease.