NBS is a DNA repair disorder with immunodeficiency and high predisposition to malignancies.
From 2012 to 2019 22 NBS patients received HSCT in our center (MSD –5, MUD –17), 12 of them had malignancies before transplantation: 4 –ALL, 7 –non-Hodgkin B-cell lymphomas, 2 –T-cell lymphoma. All were in complete remission at the time of HSCT. Conditioning regimen (CR) consisted of busulfan (4 mg/kg) or treosulfan (30 mg/m2) with fludarabine (150 mg/m2), cyclophosphamide (40 mg/m2), r-ATG (5 mg/kg) and rituximab (100 mg/m2).
The median follow-up time after HSCT was 2.38 years (0,73–5,54). All patients had primary engraftment. Four of 22 patients had neoplasms after HSCT, all patients received low dose busulfan-based CR. Two patients died, 1 of T-cell lymphoma relapse on d+41. One patient rejected graft 11 months after HSCT and died 6 months later from newly developed high-grade T-cell lymphoma. Two patients developed PTLD. In one, PTLD was limited to peripheral lymph nodes at 6 months after HSCT. He received rituximab 375 mg/m2/week №4 with complete response. Second had small lung focus of EBV-associated lymphomatoid granulomatosis before HSCT, but the radiologic enlargement of this mass was detected at d+41. Lesion biopsy showed CD30+ B-cell PTLD, patient received brentuximab vedotin (1,2 mg/m2 every 3 wks №6) accompanied by CD45RA+ depleted donor lymphocyte infusions, which resulted in PTLD resolution.
HSCT is a potential option to reduce the risk of lymphoid malignancies development and relapses in NBS patients, but longer follow-up and bigger cohort of patients are needed to evaluate HSCT efficacy.