Selective T cell‐depleted haploidentical hematopoietic stem cell transplantation for relapsed/refractory neuroblastoma

Abstract Relapsed/refractory NB carries a bleak outcome, warranting novel treatment options. HaploHSCT induces a graft‐versus‐ NB effect via natural killer cell alloreactivity. Review of patients with relapsed/refractory NB who underwent haplo HSCT with ex vivo T‐cell depletion in our unit from 2013 through 2018. Ten patients were identified (male=5; median age at haplo HSCT =6.45 y, range: 3.49‐11.02 y). Indications were relapsed in 7 and refractoriness in 3; disease status at haplo HSCT was CR in 2, PR in 6, and PD in 2. All patients received peripheral blood stem cell grafts after ex vivo T‐cell depletion ( CD 3/ CD 19‐depletion=1; TCR ‐αβ/ CD 19‐depletion=4; CD 3/ CD 45 RA ‐depletion=4; and TCR ‐αβ/ CD 45 RA ‐depletion=1). Conditioning regimens were fludarabine‐based. Neutrophils engrafted on median D + 10 (range: D + 9 to +13), and platelets engrafted (≥20 × 10 9 /L) on median D + 8 (range: D + 5 to D + 14). Early T‐ and NK ‐cell recovery were evident. Of the 10 patients, acute rejection developed in 1 (who died of PD despite rescue HSCT ), and 1 died of sepsis before engraftment; 8 experienced full donor‐chimerism post‐ HSCT . Among the 8, 6 experienced CR , 1 died of PD , and 1 died of pulmonary hypertensive crisis before evaluation. At publication, 4 were in remission (2.8, 7.4, 28.5, and 58.9 months). No significant Gv HD occurred. Haplo HSCT with selective ex vivo T‐cell depletion may be a safe and useful salvage strategy for relapsed/refractory NB .