An International Learning Collaborative Phase 2 Trial for Haploidentical Bone Marrow Transplant in Sickle Cell Disease.

In the setting of a learning collaborative, we conducted an international multicenter phase 2 clinical trial testing the hypothesis that non-myeloablative related haploidentical BMT with thiotepa and post-transplant cyclophosphamide (PTCy) will result in 2-year event-free survival (no graft failure or death) of at least 80%. A total of 70 participants (median age 19.1 (IQR 14.1 - 25.0) were evaluable based on the conditioning protocol. Graft failure occurred in 11.4% (8/70) and only in participants <18 years (p=0.001); all had autologous reconstitution. After a median follow-up of 2.4 years (IQR 1.5-3.9), the 2-year Kaplan-Meier-based probability of event-free survival was 82.6% (95% CI 71.4%-89.7%). The 2-year overall survival was 94.1% (95% CI 84.9%-97.7%) with no difference between the child and adult participants (p=0.889). After excluding participants with graft failure (n=8), participants with engraftment had median whole blood donor chimerism values at D+180 and D+365 post-transplant of 100.0% (IQR 99.8 - 100.0%; n=59) and 100.0% (IQR 100.0 - 100.0%; n=58), respectively, and 96.6% (57/59) were off immunosuppression at 1-year post-transplant. The 1-year grades III-IV acute graft versus host disease (GvHD) rate was 10.0% (95% CI 4.6 - 18.6%), and the 2-year moderate-severe chronic GvHD rate was 10.0% (95% CI 4.6 - 18.6%). Five participants (7.1%) died from infectious complications. We demonstrate that non-myeloablative haploidentical BMT with thiotepa and PTCy is a readily available curative therapy for most adults, even those with organ damage, instead of the more expensive myeloablative gene therapy and gene editing. Additional strategies are required for children to decrease graft failure rates (ClinicalTrials.gov identifier NCT01850108).

Creating an automated contemporaneous cohort in sickle cell anemia to predict survival after disease-modifying therapy.

The Food and Drug Administration requires contemporaneous controls to compare clinical outcomes for participants receiving experimental gene therapy or gene editing clinical trials. However, developing a contemporaneous cohort of rare diseases requires multiple person-hours. In a single referral center for sickle cell disease, we tested the hypothesis that we could create an automated contemporaneous cohort of children and adults with sickle cell anemia (SCA) to predict mortality. Data were obtained between 1 January 2004 and 30 April 2021. We identified 419 individuals with SCA with consistent medical care defined as followed continuously for >0.5 years with no visit gaps >3.0 years. The median age was 10.2 years (IQR, 1-24 years), with a median follow-up of 7.4 years (IQR, 3.6-13.5 years) and 47 deaths. A total of 98% (274 of 277) of the children remained alive at 18 years of age, and 34.3% (94 of 274) of those children were followed into adulthood. For adults, the median age of survival was 49.3 years. Treatment groups were mutually exclusive and in a hierarchical order: hematopoietic stem cell transplant (n = 22)>regular blood transfusion for at least 2 years (n = 56)>hydroxyurea for at least 1 year (n = 243)>no disease-modifying therapy (n = 98). Compared to those receiving no disease-modifying treatment, those treated with hydroxyurea therapy had a significantly lower hazard of mortality (hazard ratio = 0.38; P = 0.016), but no statistical difference for those receiving regular blood transfusions compared to no disease-modifying therapy (hazard ratio = 0.71; P = 0.440). An automated contemporaneous SCA cohort can be generated to estimate mortality in children and adults with SCA.

Reduction in the Prevalence of Thrombotic Events in Sickle Cell Disease after Allogeneic Hematopoietic Transplantation.

Thrombosis is a recognized complication in sickle cell disease (SCD). Allogeneic hematopoietic cell transplantation (allo-HCT) remains the sole curative option for patients with severe SCD phenotypes. Data describing the effects of allo-HCT on recurrent thrombotic events (venous and arterial events) are limited, however. We evaluated 31 patients with SCD who underwent allo-HCT with a median follow-up of 34.5 months (range, 13 to 115) post-transplantation. No patient continued anticoagulation or antiplatelet therapy after allo-HCT. There was an absolute difference of 32% (95% confidence interval [CI], 12.3% to 32.2%; P = .002) in the prevalence of venous thromboembolic (VTE) events before and after allo-HSCT. In addition, there was an absolute difference of 38.5% (95% CI, 10.63 to 45.96; P = .006) in the number of ischemic cerebrovascular accidents (CVAs) occurring before and after allo-HSCT. Patients with severe SCD who undergo allo-HCT are less likely to develop recurrent thrombotic events compared with a control cohort of patients matched for age and genotype (odds ratio, 0.22; 95% CI, 0.058 to 0.83; P = .025). Following curative therapy with allo-HCT, there is a reduction in recurrent arterial and venous thrombosis in patients with severe SCD phenotypes.

Using novel magnetic resonance imaging methods to predict stroke risk in individuals with sickle cell anemia.

Sickle cell anemia (SCA) is a well-characterized monogenetic disorder with a high prevalence of cerebral vasculopathy, silent cerebral infarcts, and strokes. A significant mechanism for cerebral infarction in SCA is hemodynamic imbalance. To compensate for reduced oxygen-carrying capacity due to anemia, individuals with SCA have chronically elevated cerebral blood flow to maintain viable oxygen delivery to the brain tissue. Often the oxygen extraction fraction (ratio of oxygen consumed to oxygen delivered) is increased in more severely affected individuals. Subsequently, cerebrovascular reserve capacity, the ability of arterioles to dilate and further increase the cerebral blood volume and flow, will be reduced. These hemodynamic profiles have been associated with prior cerebral infarcts and increased evidence of disease severity. These cerebral hemodynamic parameters can be assessed noninvasively with noncontrast magnetic resonance imaging (MRI) of the brain utilizing specific MRI methods. This review focuses on using advanced neuroimaging methods to assess stroke risk in individuals with SCA, and such methods may be utilized before and after bone marrow or hematopoietic stem cell transplant to assess cerebral hemodynamic response. This manuscript is part of the Proceeding of The European Group for Blood and Marrow Transplantation (EBMT) Congress on Sickle Cell Disease, 16th-17 May 2019, Regensburg, Germany.

Phase 2 trial of montelukast for prevention of pain in sickle cell disease.

Cysteinyl leukotrienes (CysLTs) are lipid mediators of inflammation. In patients with sickle cell disease (SCD), levels of CysLTs are increased compared with controls and associated with a higher rate of hospitalization for pain. We tested the hypothesis that administration of the CysLT receptor antagonist montelukast would improve SCD-related comorbidities, including pain, in adolescents and adults with SCD. In a phase 2 randomized trial, we administered montelukast or placebo for 8 weeks. The primary outcome measure was a >30% reduction in soluble vascular cell adhesion molecule 1 (sVCAM), a marker of vascular injury. Secondary outcome measures were reduction in daily pain, improvement in pulmonary function, and improvement in microvascular blood flow, as measured by laser Doppler velocimetry. Forty-two participants with SCD were randomized to receive montelukast or placebo for 8 weeks. We found no difference between the montelukast and placebo groups with regard to the levels of sVCAM, reported pain, pulmonary function, or microvascular blood flow. Although montelukast is an effective treatment for asthma, we did not find benefit for SCD-related outcomes. This clinical trial was registered at www.clinicaltrials.gov as #NCT01960413.

Risk Factors for 30-Day Readmission in Adults with Sickle Cell Disease.

BACKGROUND: Readmission to the hospital within 30 days is a measure of quality care; however, only few modifiable risk factors for 30-day readmission in adults with sickle cell disease are known. METHODS: We performed a retrospective review of the medical records of adults with sickle cell disease at a tertiary care center, to identify potentially modifiable risk factors for 30-day readmission due to vasoocclusive pain episodes. A total of 88 patients ≥18 years of age were followed for 3.5 years between 2010 and 2013, for 158 first admissions for vasoocclusive pain episodes. Of these, those subsequently readmitted (cases) or not readmitted (controls) within 30 days of their index admissions were identified. Seven risk factors were included in a multivariable model to predict readmission: age, sex, hemoglobin phenotype, median oxygen saturation level, listing of primary care provider, type of health insurance, and number of hospitalized vasoocclusive pain episodes in the prior year. RESULTS: Mean age at admission was 31.7 (18-59) years; median time to readmission was 11 days (interquartile range 20 days). Absence of a primary care provider listed in the electronic medical record (odds ratio 0.38; 95% confidence interval, 0.16-0.91; P = .030) and the number of vasoocclusive pain episodes requiring hospitalization in the prior year were significant risk factors for 30-day readmission (odds ratio 1.30; 95% confidence interval, 1.16-1.44; P <.001). CONCLUSION: Improved discharge planning and ensuring access to a primary care provider may decrease the 30-day readmission rate in adults with sickle cell disease.