Autologous BMT in high risk patients with CALLA-positive ALL: possible efficacy of ex vivo marrow leukemia cell purging with monoclonal antibodies and complement.

Autologous BMT (auto-BMT) has been conducted for 17 high-risk common ALL antigen (CALLA)-positive non-T cell type ALL patients. Ex vivo purging of leukemia cells from infused BM cells was performed using complement and three kinds of mouse monoclonal antibodies reactive to CALLA-positive leukemia cells: NL-1 (IgG2a), NL-22 (IgM), and HL-47 (IgM). Minimal residual leukemia cells in BM were examined by PCR method in Philadelphia chromosome (Ph 1 )-positive ALL cases. BCR/ABL chimeric transcript, which was positive in BM samples before purging, was shown to be absent after ex vivo purging in all three cases tested. Among four Ph 1 -positive cases transplanted in first CR, three cases survived in CR remission 77, 29 and 26 months after BMT, and one case died without relapse 4 months after BMT