Allogeneic hematopoietic stem-cell transplantation from haploidentical donors using 'ex-vivo' T-cell depletion in pediatric patients with hematological malignancies: state of the art review.

PURPOSE OF REVIEW: Nowadays, T-cell-depleted haploidentical transplantation is considered a valid approach for children lacking a human leukocyte antigen (HLA) identical donor for allogeneic transplantation. This kind of allogeneic transplant is now widely used especially for pediatric patients with high-risk hematological malignancies. However, relapsing disease and life-threatening viral infections are still relevant clinical problems as a consequence of delayed immune reconstitution. Adoptive cell therapies have been proposed to overcome this problem.

RECENT FINDINGS: After initial clinical approach using CD34+ selection as method for T-cell depletion (TCD), it was observed that immune reconstitution was delayed and it resulted on high incidence of opportunistic infections and nonrelapse mortality. It is now evident that development over time of graft manipulation techniques for TCD, have provide clinicians a useful tool for overcoming transplant complication such as graft failure, severe graft-vs.-host disease and opportunistic infections. As such, several procedures of almost total or partial TCD have been developed including CD3/CD19 depletion, T cell receptor αβ/CD19 depletion and more recently CD45RA+ depletion. Recent studies showed that immune reconstitution is associated with transplant outcomes. Based on this, haploidentical transplantation is now been explored as platform for cellular therapy to prevent disease recurrence or to treat clinical complications.

SUMMARY: Allogeneic transplantation still remains a standard of care for pediatric patients with high-risk hematological malignancies. In absence of an HLA identical donor, T-cell-depleted haploidentical transplant is now considered a valid option and provide a platform for cellular therapy to prevent relapse disease or to treat opportunistic infections.