Durable and complete hematopoietic reconstitution after autografting of rhGM-CSF exposed peripheral blood progenitor cells.

Two patients with poor prognosis stage III multiple myeloma have been treated with myeloablative chemoradiotherapy, i.e. 10 Gy fractionated total body irradiation plus 120 mg/m2 intravenous melphalan, and then transplanted with autologous peripheral blood cells harvested by four leukaphereses during the phase of rapid hematopoietic recovery following induction therapy with high-dose (2 g/m2) etoposide and recombinant human glycosylated granulocyte macrophage-colony stimulating factor (rhGM-CSF). Following myeloablative therapy and autologous peripheral blood cell transplantation, both patients experienced brief pancytopenia followed by rapid hematopoietic recovery of leukocytes (time to greater than 500 x 10(6)/l = 12 days) and platelets (time to greater than 100 x 10(9)/l = 14 days). In particular, single donor platelet transfusion requirements were limited to one and two transfusions per patient, respectively. Reconstitution has so far been maintained throughout the follow-up period for the two patients (9 and 6 months, respectively). These two cases show that rhGM-CSF-exposed peripheral blood cells are capable of producing prompt and sustained hematopoietic reconstitution in patients treated with myeloablative chemoradiotherapy.