Clinical Scorecard: Haploidentical stem cell transplantation with αß T-cell depletion in pediatric and young adult patients suffering from transfusion-dependent beta-thalassemia

At a Glance

Key Highlights

• HSCT from matched donors is standard but limited by donor availability, especially in ethnic minorities
• Haploidentical HSCT with TCRαβ/CD19+ depletion offers a feasible alternative with promising survival outcomes
• Treosulfan-based conditioning regimen shows lower toxicity and effective myeloablation in non-malignant diseases including TDT

Guideline-Based Recommendations

Diagnosis

• Confirm transfusion-dependent beta-thalassemia via genetic and clinical assessment
• Assess iron overload and organ damage using MRI, ultrasound, and liver biopsy
• Classify patients by Pesaro risk classification to guide transplant timing

Management

• Prioritize HSCT before development of significant iron overload and organ complications, ideally before age 14
• Use haploidentical HSCT with ex vivo αß T-cell and CD19+ B-cell depletion when matched sibling donors are unavailable
• Employ treosulfan-based conditioning regimen combined with thiotepa and fludarabine for reduced toxicity
• Perform donor selection prioritizing absence of donor-specific antibodies and HLA compatibility
• Consider intensified iron chelation pre-transplant in patients with substantial iron overload

Monitoring & Follow-up

• Monitor for graft failure with backup autologous bone marrow available
• Regularly assess for graft-versus-host disease, especially acute and chronic forms
• Evaluate organ function post-transplant, focusing on liver and cardiac status
• Perform cross-match analyses for donor-specific antibodies pre-transplant

Risks

• Risk of graft failure increased by hyperplastic marrow, alloimmunization, and anti-HLA antibodies
• High incidence of sinusoidal obstruction syndrome/veno-occlusive disease exacerbated by busulfan conditioning
• Post-transplant cyclophosphamide regimens associated with high rates of acute and chronic GvHD
• Iron overload-related organ damage may complicate transplant outcomes

Patient & Prescribing Data

20 pediatric and young adult TDT patients (median age 10 years) including those with no matched sibling donor

TCRαβ/CD19+ depleted haplo-HSCT showed comparable overall survival and event-free survival to matched sibling donor HSCT with manageable toxicity

Clinical Best Practices

• Perform HSCT early in disease course before irreversible organ damage
• Use ex vivo αß T-cell and CD19+ B-cell depletion to reduce GvHD risk in haploidentical HSCT
• Apply treosulfan-based conditioning regimen for effective myeloablation with reduced toxicity
• Screen and select donors carefully to avoid donor-specific antibodies and major incompatibilities
• Prepare backup autologous bone marrow harvest in haplo-HSCT for graft failure rescue
• Intensify iron chelation therapy pre-transplant in patients with significant iron overload

References

• Beta-thalassemia overview and mutations
• HSCT standard of care and outcomes in TDT
• Treosulfan conditioning in non-malignant diseases
• Haploidentical HSCT with αß T-cell depletion
• Pesaro risk classification in thalassemia