Reduced Intensity Transplantation for Severe Sickle Cell Disease

  • End date
    Jul 1, 2025
  • participants needed
  • sponsor
    St. Jude Children's Research Hospital
Updated on 29 May 2022
cell transplantation
cerebral blood flow
acute chest syndrome
chest syndrome
transcranial doppler ultrasonography
sickle cell trait
splenic sequestration


This study is being done to test a transplant method that may have fewer side effects (or less toxic, less harmful) than conventional high dose chemotherapy conditioning-based transplants for children and young adults with Sickle Cell Disease (SCD). Patients less than or equal to 25 years old with SCD who would likely benefit from allogeneic hematopoietic cell transplantation (HCT) will be included in this study. Patients with a suitable HLA matched sibling donor (MSD) will be enrolled on the MSD arm while patients without an eligible MSD who have a suitable haploidentical (HAPLO) donor available will be enrolled on the HAPLO arm of the study.

Primary Objective

To assess the donor T-cell chimerism at 1-year post transplant in each respective arm (MSD, HAPLO) of the trial.

Secondary Objectives

  • Assess the overall survival and 1-year, 2-year and 3-year post-transplant graft versus host disease (GVHD)-free SCD-free survival.
  • Estimate the primary and secondary graft rejection rate at 1-year, 2-year and 3-year post- transplant.
  • Estimate the incidence and severity of acute and chronic (GVHD).
  • Estimate the incidence of SCD recurrence after transplant
  • Assess the neutrophil and platelet recovery kinetics post-transplant.

Exploratory Objectives

  • Record immune reconstitution parameters, including chimerism analysis, quantitative lymphocyte subsets, T cell receptor excision circle (TREC) analysis, V-beta spectratyping, and lymphocyte phenotype and function.
  • Conduct longitudinal examination of impact of HCT on patient health-related quality of life (HRQL) and adjustment, and parental adjustment.
  • Examine impact of HCT on patient cognitive and academic function.
  • Determine factors that influenced the decision to undergo HCT, explore perceptions of the HCT experience, and assess decisional satisfaction/regret.
  • Develop and evaluate an objective/quantitative imaging biomarker to assess organ (liver and heart) function/disease status and changes following HCT.
  • Develop and evaluate an objective/quantitative imaging biomarker to determine cerebral blood flow and oxygen extraction fraction following HCT.


This is a prospective single center phase II study of a reduced intensity conditioning based hematopoietic cell transplant for patients with sickle cell disease. In this study, patients with SCD who would be expected to benefit from an allogeneic HCT will receive an unmanipulated peripheral blood derived hematopoietic stem and progenitor cell (HSPC) graft from either an MSD or HAPLO donor after a reduced intensity conditioning regimen comprising of alemtuzumab, thiotepa and low dose total body irradiation. All patients will receive a pre-conditioning phase comprising of hydroxyurea and azathioprine to reduce the risk of graft rejection. GVHD prophylaxis will consist of sirolimus. Patients on the HAPLO arm will also receive two doses of post-transplant cyclophosphamide. All patients will receive regularly scheduled low dose donor lymphocyte infusions till donor lymphocyte chimerism reaches at least 90% donor. The main objective of this study is to improve graft function and immune reconstitution after a reduced intensity conditioning based transplant.

Condition Sickle Cell Disease
Treatment hydroxyurea, azathioprine, alemtuzumab, thioptepa, low dose total body irradiation and sirolimus, hydroxyurea, azathioprine, alemtuzumab, thiotepa, plerixafor, low dose total body irradiation, cyclophosphamide and sirolimus
Clinical Study IdentifierNCT04362293
SponsorSt. Jude Children's Research Hospital
Last Modified on29 May 2022


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