Patients with severe sickle cell disease (SCD) experienced fewer thrombotic events after allogeneic hematopoietic cell transplantation (allo-HCT), according to the results of a study published in Transplantation and Cellular Therapy.

There was an absolute reduction of 32% (P =.002) in venous thromboembolic (VTE) events and an absolute 38.5% reduction in ischemic cerebrovascular accidents (CVA) when comparing pre- and post-allo-HCT. Prior to allo-HCT therapy, a total of 10 patients had experienced VTE events and 11 had ischemic CVA.

After transplantation, 3 patients experienced deep vein thrombosis (DVT) and 1 of those also experienced an embolic CVA. A history of provoked VTE was present in 2 of these patients. The patient who experienced both a DVT and embolic stroke had venous catheter use with patent foramen ovale.

All thrombotic events after allo-HCT occurred within the first 30 days. The 3 patients who experienced DVT were given either direct oral anticoagulants (n=2) or low molecular weight heparin (n=1) to prevent further thrombotic events. The median follow-up time was 78.5 months (range, 14-216 months).

“Perhaps the most intriguing aspect of the data presented is the apparent durable reduction in thrombosis recurrence in allo-HSCT patients who had a severe prior thrombotic history,” the authors said. “This highlights a salient but critical point that transplantation has the potential to free patients from lifelong anticoagulation and the financial or bleeding complications associated with it.”

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When compared to matched controls, patients who received allo-HSCT were less likely to develop recurrent thrombotic events with a hazard ratio (HR) of 0.0006 (95% CI, .0002-.00015; P =.00001) of patients developing recurrent arterial events and an HR of 0.38 (95% CI, .15-.92; P =.05) for venous events.

A total of 9 patients developed acute graft versus host disease (GVHD) with only 2 patients experiencing moderate chronic GVHD after day 100 of the study. The authors noted that the occurrence of GVHD was not positively associated with the recurrence of thrombosis in this cohort as patients who developed GVHD did so much later after their thrombotic event.

A total of 31 patients with severe SCD who received allo-HCT met the inclusion criteria and were included in the study. Of these, 28 underwent human leukocyte antigen-haploidentical bone marrow transplant and the other 3 had myeloablative matched sibling donor transplants. A total of 53 patients with severe SCD were included in the age- and genotype-matched control group.


Patel A, Wilkerson K, Chen H, et al. Reduction in prevalence of thrombotic events in sickle cell disease after allogeneic hematopoietic transplantation. Transplantation and Cellular Therapy. Published online February 15, 2022. doi:10.1016/j.jtct.2022.02.010