ALLOGENEIC PERIPHERAL-BLOOD PROGENITOR CELLS FOR TREATMENT OF RELAPSEAFTER BONE-MARROW TRANSPLANTATION

Donor leukocyte infusions (DLI) are an effective therapy for patients who relapse with leukemia after bone marrow transplantation (BMT). Sev ere graft-versus-host disease and prolonged periods of pancytopenia co mpromise the success of this treatment in a substantial number of pati ents. We used filgrastim-mobilized peripheral blood progenitor cells ( PBPCs), in some cases preceded by cytoreductive therapy, to circumvent some of the problems associated with DLI. Eleven patients (median age 41 years) received a total of 20 donor cell infusions. Their diagnosi s was CML in hematological (two patients) or cytogenetic relapse (two patients), six patients suffered from acute myeloid leukemia (AM; n = 5) or Philadelphia chromosome-positive acute lymphoblastic leukemia (A LL Ph+). One patient had multiple myeloma (MM). All six patients with acute leukemias received cytoreductive therapy prior to PBPC infusions ; three patients with CML were pretreated with IFN alpha. Four of four patients with CML responded to PBPC infusions and currently are in co mplete clinical and molecular remission for time periods between 1 and 12 months. Six of six patients with acute leukemias achieved a comple te remission. All of them relapsed after a median remission duration o f 24 weeks (range 11-49 weeks). Three patients relapsed at extramedull ary sites (CNS, testes, skin). Four of six acute leukemia patients rec eived further cytoreductive therapy. All patients responded again and are in complete remission far time periods between 14 and 615 days. Tw o patients with acute leukemias have died due to dissemination of the disease. The patient with MM did not respond and is alive with disease . Severe (grade III) acute GVHD developed in two of 11 patients, three patients developed grade II disease, six patients did not show any si gns of GVHD. Extensive chronic GVHD has developed in two cases to date . Patients with chemotherapy prior to PBPC infusion developed neutrope nia and thrombocytopenia with a maximum duration of 20 and 14 days, re spectively; prolonged periods of neutropenia did not occur. Two patien ts developed long-lasting thrombocytopenia in spite of PBPC infusion, in one case followed by leukemic relapse. Repeated courses of chemothe rapy and PBPC infusion were generally tolerated well; no early deaths due to treatment-related toxicity or GVHD were observed. We conclude t hat the use of allogeneic PBPC instead of DLI in patients with relapse after BMT is technically feasible and safe. The efficacy of PBPC infu sions seems comparable to DLI in patients with CML. Patients with acut e leukemias also achieved complete albeit transient remissions. Aggres sive chemotherapy followed by PBPC infusions resulted in only limited duration of cytopenia. The usage of PBPC infusion instead of non G-CSF -mobilized donor cells for treatment of relapse after BMT may reduce p ancytopenia-related complications and merits further investigation.