Encouraging Outcomes of Hematopoeitic Stem Cell Transplantation in Pediatric Sickle Cell Disease- A Decade-Long Experience from the Developing World.

Abstract

Sickle cell disease (SCD) is the most common hemoglobinopathy, affecting approximately 300,000 newborns worldwide each year. Hematopoietic stem cell transplantation (HSCT) is the only current curative option for the disease. Still, it is hindered by the availability of suitable donors, socio-economic issues, transplant failure and long-term complications of transplant, including graft-versus-host disease-acute and chronic. To date, there is no standardized protocol for conditioning regimens in SCD patients. A total of 100 pediatric patients diagnosed with sickle cell disease (SCD) underwent allogeneic hematopoietic stem cell transplantation (HSCT) between January 2015 and December 2024. Fifty-five patients (59.8%) underwent HLA-identical sibling-donor, and 37(40.2%) underwent haploidentical transplants. Eighty-three (91.2%) had stable engraftment. The median follow-up time was 31.6 months. Overall survival was 86.9%(95% CI: 79.3%-93.4%) in our cohort of 92 patients transplanted for SCD from either HLA-matched siblings or haploidentical donors, with a median follow-up of 53 months, with EFS of 77% without death or rejection. The survival rates were significantly higher in MSD HSCT (53/55, 96.4% vs 27/37, 78.3%, p < 0.01). The outcomes in haploidentical outcomes have significantly improved (2014-2018 vs 2019 to 2023). The cumulative incidence of acute graft-versus-host-disease (GVHD) was 26% (95% CI - 17.9% to 36.8%) and of chronic GVHD was 8.4% (95% CI - 3.7% to 17.1%) at 2-year post-transplant. Viral reactivations were seen in 18 patients. In haploidentical transplants, we gradually drifted toward reduced toxicity conditioning, including Thio-Flu-Cy-TBI-ATG and found better outcomes through the years. The use of post-transplantation (PTCy) has led to a significantly reduced risk of GVHD.