Double allogeneic peripheral stem cell transplants for patients at high risk of relapse

Patients with chronic myeloid leukemia (CML) relapsing in blast crisis after HLA-identical sibling bone marrow transplantation (BMT) are difficult to treat. Infusion of donor lymphocytes or retransplantation are unlikely to result in long-term disease-free survival. Treatment intensification with allogeneic double-BMT, made possible by using repeatedly mobilized peripheral blood stem cells, offers a new treatment option. We report two patients with Philadelphia chromosome positive CML transplanted in chronic phase, relapsing with CML in myeloid blast crisis. Both received intensive induction chemotherapy (ICE) followed by a first, T cell-depleted peripheral stem cell transplant from the initial donor. Both patients engrafted rapidly (day 15). Upon hematologic recovery, a second G-CSF mobilized non-T cell-depleted peripheral stem cell transplant from the same donor was given after pretransplant conditioning with busulphan and cyclophosphamide. Again, engraftment was rapid (days 18 and 16) and both patients are alive and disease-free 18 and 21 months after allogeneic double-BMT. G-CSF mobilized peripheral stem cells allow new ways of treatment intensification with double-BMT in refractory leukemias relapsing post-transplant. This approach warrants further study.