在先天性非恶性疾病患儿中，TCR-αβ(+) 和 CD19(+) 细胞去除后的单倍体相合干细胞移植

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) represents a valuable alternative for children with nonmalignant disease and ex vivo negative selection of TCR-αβ + cells is an emerging graft manipulation option that carries several potential advantages in terms of reduced risk of graft-versus-host disease (GvHD) and improved immune reconstitution.

We report all consecutive patients with a diagnosis of nonmalignant disease who received a TCR-αβ + and CD19 + depleted haplo-HSCT at "IRCCS Istituto Giannina Gaslini" from 2013 to 2019; the conditioning regimen was myeloablative or non-myeloablative, depending on underlying disease; all patients received antithymocyte globulin and rituximab. No post-transplantation GvHD prophylaxis was given in presence of a TCR-αβ + cell dose in the graft lower than the threshold of 1 × 10 5 /kg of the recipient's weight. Among 20 HSCTs, engraftment occurred in 17 (85%) after a median of 14 and 12 days from graft infusion for neutrophils and platelets, respectively. Primary graft failure was diagnosed in 3 (15%) patients, and 2 (10%) experienced secondary rejection; all of these patients underwent a second HSCT.

The cumulative incidence of a-GvHD and c-GvHD was 15% (2 = grade 1, 1 = grade 4) at 90 days and 5% (1 = grade 1) at 7 months, respectively. Cytomegalovirus reactivation requiring pre-emptive treatment was observed in 9 patients (45%). One patient developed a JC virus-related progressive multifocal leukoencephalopathy, successfully managed with donor-derived virus-specific T-cell infusions. A complete immunological recovery was reached in most patients within 6 months.

After a median follow-up of 4 years, 18 patients are alive, with a cumulative survival probability of 90%. Haplo-HSCT after ex vivo TCR-αβ + /CD19 + negative selection may be considered a good option for children with nonmalignant diseases because it ensures a high engraftment rate with an acceptable risk of graft failure, very low incidence of significant GvHD, and good immune reconstitution with low frequency of severe virus-related disease.

However, the control of viral infection/reactivation should be kept high to promptly provide pre-emptive treatments and approaches of antiviral adoptive immunotherapy.