A pilot study of cytoreductive chemotherapy combined with infusion of additional peripheral blood stem cells reserved at time of harvest for transplantation in case of relapsed hematologic malignancies after allogeneic peripheral blood stem cell transplant.

Reharvesting leukocytes from donors for a donor leukocyte infusion (DLI) is inconvenient and occasionally impossible in case of unrelated donors. It is well known that the effect of a growth factor-primed DLI is comparable to that of a nonprimed DLI. In total, 42 patients with hematologic malignancies and a high risk of relapse were allocated, on an intent-to-treat basis, a peripheral blood stem cell transplantation (PBSCT) from HLA-matched sibling donors, and then at the time of harvest, additional peripheral blood stem cells (PBSCs) were also reserved for a therapeutic primed DLI in case of relapse. In all, 12 patients who relapsed after allogeneic PBSCT were treated with mainly cytarabine-based chemotherapy followed by a cryopreserved PBSC infusion. The median dose of CD3+ and CD34+ cells for the primed DLIs was 1.43 x 10(8)/kg and 4.75 x 10(6)/kg, respectively. Six of the 12 relapsed patients exhibited a complete response after the primed DLI, plus their 1-year survival rate was 33%. The new development or progression of graft-versus-host disease after a primed DLI was observed in 50% of the patients. Overall, the survival at 1 year was 16.7%. Accordingly, the induction of a graft-versus-leukemia effect through a primed DLI, using additional PBSCs reserved at the original time of harvest, would appear to be feasible for patients with relapsed hematologic malignancies. Furthermore, this approach is also more convenient for donors.