Influence of severe combined immunodeficiency phenotype on the outcome of HLA non-identical, T-cell-depleted bone marrow transplantation - A retrospective European survey from the European Group for Bone Marrow Transplantation and the European Society for Immunodeficiency

We analyzed the outcomes of 214 HLA non-identical T-cell-depleted bone marr ow transplantations (BMTs), performed in 178 consecutive patients for treat ment of severe combined immunodeficiencies (SCID). Patients were treated in 18 European centers between 1981 and March 1995. SCID variants, that is, a bsence of T and B lymphocytes (B-) or absence of T cells with presence of B lymphocytes (B+) were found to have a major influence on outcome. The dise ase-free survival was significantly better for patients with B+ SCID (60%) as compared with patients with B-SCID (35%) (P = .002), with a median follo w-up of 57 months and 52 months, respectively. Other factors associated wit h a poor prognosis were the presence of a lung infection before BMT (odds r atio = 2.47 [1.99-2.94]) and the use of monoclonal antibodies for T-cell de pletion of the graft (odds ratio = 1.67 [1.18-2.15]). Additional factors in fluencing outcome were age at BMT (<6 months) and period during which BMT w as performed. Better results were achieved after 1991. Reduced survival of patients with B- SCID was associated with a higher incidence of early death s from infection, a diminished rate of marrow engraftment, a trend to a hig her incidence of chronic graft-versus-host disease, and slower kinetics of T/B immune function development. In both groups of patients, the use of bus ulfan (8 mg/kg total dose) and cyclophosphamide (200 mg/kg total dose) as a conditioning regimen provided the best cure rate (74% for patients with B SCID and 43% for patients with B- SCID, respectively), although results we re not statistically significantly different from other regimens. This retr ospective analysis should lead to the design of adapted measures to the per formance of HLA non-identical BMT in patients with distinct SCID conditions .