By transferring a neomycin resistance marker gene into the marrow cells of 20 patients before transplantation, we were able to trace the pattern of haemopoietic reconstitution postinfusion. The marker gene was present and expressed in all haemopoietic lineages in vivo in 15 of 18 evaluable patients at 1 month post-transplantation, in 8 of 9 patients at 6 months, and in 5 of 5 at 1 year. The marker has remained detectable for up to 18 months-the duration of our study.

Our findings indicate that harvested bone marrow consistently contributes to long-term multilineage recovery of haemopoiesis after autologous marrow transplantation in cancer patients. These results, provide a rationale for the continued exploration of more ablative preparative regimens with single or sequential autologous marrow transplants.