Outcome of transplantation of highly purified peripheral blood CD34+ cells with T-cell add-back compared with unmanipulated bone marrow or peripheral blood stem cells from HLA-identical sibling donors in patients with first chronic phase chronic myeloid leukemia.

Outcomes of highly purified CD34(+) peripheral blood stem cell transplantation (PBSCT) for chronic phase chronic myeloid leukemia (CML) (n = 32) were compared with those of PBSCT (n = 19) and of bone marrow transplantation (BMT) (n = 22) in the HLA-compatible sibling donor setting. Median follow-up was 18 months after CD34(+)-PBSCT and unmanipulated PBSCT and 20 months after BMT. CD34(+)-PBSCT was associated with delayed T-cell immune reconstitution at 3 months and 12 months after transplantation compared with PBSCT (P <.001) or BMT (not significant [NS]). The estimated probability of grades II to IV acute graft-versus-host disease (GVHD) was 60% +/- 13% for the PBSCT group, 37% +/- 13% for the BMT group, and only 14% +/- 8% for the CD34(+)-PBSCT group (CD34-PBSCT versus BMT, P <.01; and CD34-PBSCT versus PBSCT, P <.001). The probabilities for molecular relapse were 88% for CD34(+)-PBSCT, 55% after BMT, and 37% after PBSCT (CD34(+)-PBSCT versus PBSCT, P <.03). Cytogenetic relapse probability was 58% after CD34(+)-PBSCT, 42% after BMT, and 28% after PBSCT (NS). After CD34(+)-PBSCT, 26 of 32 patients received a T-cell add-back. Hematologic relapse occurred in 4 of 22 patients after BMT, in 3 of 19 patients after PBSCT, and in only 1 of 32 patients after CD34(+)-PBSCT. The occurrence of a hematologic relapse in patients receiving CD34(+)-PBSC transplants was prevented by donor leukocyte infusions, which were applied at a median of 4 times (range, 1-7 times) with a median T-cell dose of 3.3 x 10(6) x kg/body weight [at a median] beginning at day 120 (range, 60-690 days). The estimated probability of 3-year survival after transplantation was 90% in the CD34(+)-PBSCT group, 68% in the PBSCT group, and 63% in the BMT group (CD34-PBSCT versus BMT, P <.01; and CD34-PBSCT versus PBSCT, P <.03). Transplantation of CD34(+)-PBSCs with T-cell add-back for patients with CML in first chronic phase seems to be safe and is an encouraging alternative transplant procedure to BMT or PBSCT.