Autologous peripheral blood stem cell transplantation for acute leukaemias.

Initial interest in autologous blood stem cell transplants (ABSCT) in acute myeloid leukaemia (AML) was based on the postulate that there might be less malignant contamination than with bone marrow transplants. Although this remains presently uncertain, other advantages of ABSCT, such as a rapid haematopoietic recovery, were immediately recognized. In pilot studies, peripheral blood stem cells (PBSC) were collected after standard induction and consolidation courses of chemotherapy. The actuarial disease-free survival (DFS) and relapse rates (RR) at 2-3 years ranged from 28 to 39% and 57 to 60%, respectively. Recently, PBSC collection after high-dose cytarabine, with or without G-CSF, has been associated with DFS ranging from 47 to 57%. Thus, the timing of stem cell collection seems to be crucial in AML and it should be performed following an efficient in vivo purging but before the haematopoietic reserve is exhausted. Clinical results with ABSCT are similar to those seen after autologous bone marrow transplant (ABMT), although important issues such as potential contamination of stem cell collections and optimal timing of PBSC harvest remain to be clarified. Prospective randomized studies comparing ABMT and ABSCT are needed for definitive evaluation of the role of the source of stem cells in AML treatment.     

Haemopoietic reconstitution after autologous blood stem cell transplantation in patients with malignancies: a multicentre retrospective study

A retrospective study was undertaken to evaluate the efficacy of autologous blood stem cell transplantation (ABSCT) in terms of haemopoietic reconstitution after ablative chemotherapy or chemo-radiotherapy. 55 patients with malignancies, observed in four Italian institutions from January 1987 to June 1991, were eligible for evaluation. This series included 19 non-Hodgkin's lymphoma, 11 multiple myeloma, nine ovarian cancer, seven Hodgkin's disease, seven non-lymphocytic leukaemia, one acute lymphoblastic leukaemia, one neuroblastoma. 522 PBSC collections were performed on 55 patients. Following ABSCT, the rate of engraftment was positively related to the dose of CFU-GM infused and negatively to the presence of bone marrow involvement at conditioning. 48 patients out of 55 transplanted (87%) had rapid, complete and sustained engraftment. Three patients (5%) died of transplant-related complications. Considering that 60% of the patients in this series were in partial remission or in progressive disease at the time of ABSCT, we conclude that ABSCT is a safe approach for the use of ablative conditioning therapy in patients with a wide scope of malignancies, provided that a large number of CFU-GM have been collected after mobilizing treatment.     

Peripheral Blood Stem Cell Collection after Intermediate-Dose Cytarabine in Adult Patients with Acute Myeloblastic Leukemia Undergoing Autologous Blood Stem Cell Transplantation in First Complete Remission

Different strategies for collecting peripheral blood stem cells (PBSC) for autologous blood stem cell transplantation (ABSCT) have been reported for patients with acute myeloblastic leukemia (AML). We compared the clinical results of 2 consecutive protocols in 75 adult patients with AML in first complete remission who underwent ABSCT. In the first 56 patients (group A), PBSC were collected after induction and/or consolidation chemotherapy courses. In the subsequent 19 patients (group B), PBSC collection was done after a further intensification course with intermediate-dose cytarabine and mitoxantrone. Hematopoietic engraftment was similar in the 2 groups, with the median times to reach 0.5 x 10(9) neutrophils/L and 20 x 10(9) platelets/L being 13 days each in group A, and 12 days and 24 days, respectively, in group B. There were 3 graft failures (all in group A) and 5 transplantation-related deaths (6.6%, 4 in group A and 1 in group B). Although not statistically significant, the 3-year probabilities of both relapse (31% versus 66%; P = .12) and disease-free survival (60% versus 36%; P = .1) compared favorably for group B. Our study suggests that collection of PBSC after additional intensification can result in a better outcome for AML patients who undergo ABSCT.     

Circulating autologous stem cells collected in very early remission from acute non-lymphoblastic leukaemia produce prompt but incomplete haemopoietic reconstitution after high dose melphalan or supralethal chemoradiotherapy

Haemopoietic reconstitution (HR) using autologous peripheral blood stem cells (PBSC) was attempted after intensive chemotherapy or chemoradiotherapy in two patients with relapsed acute non-lymphoblastic leukaemia (ANLL). The PBSC were collected by leukapheresis very early in first remission and cryopreserved in liquid nitrogen. Both patients demonstrated early evidence of trilineage engraftment. The first patient received melphalan 200 mg/m2 followed by rescue with 1.3 X 10(8) mononuclear cells/kg body weight containing 29 X 10(4) granulocyte-macrophage progenitor cells (CFU-GM)/kg, and HR was evident by Day 14. The second patient was treated with supralethal chemoradiotherapy followed by rescue with 3.0 X 10(8) mononuclear cells/kg containing 23 X 10(4) CFU-GM/kg. He demonstrated early engraftment with near normal peripheral blood counts by Day 16. There was a subsequent fall in both bone marrow cellularity and peripheral blood counts to a level of low but persistent activity. There was a further phase of haematological recovery from 8 weeks following transplantation with an increase in peripheral blood counts and bone marrow cellularity until final relapse at 13 weeks. This study demonstrates that circulating stem cells have haemopoietic reconstitutive capacity, previously only shown with buffy coat cells from chronic granulocytic leukaemia. The minimum number of PBSC required for satisfactory engraftment remains unknown, although it seems probable that the ratio of pluripotent stem cells to committed progenitor cells is lower in very early remission peripheral blood than in either allogeneic normal bone marrow or autologous bone marrow collected later in stable remission. The question of leukaemic contamination of the PBSC remains to be answered.     

Chemotherapy plus G-CSF mobilized peripheral blood stem cell harvests from acute myeloid leukaemia patients contain large amounts of polyclonal myeloid linnegCD11cpos dendritic precursor cells

Dendritic cells (DC) are potent antigen-presenting cells that can induce effective tumour-specific T-cell responses. This study investigated leucapheresis products as source of DC precursors in 48 patients undergoing autologous peripheral blood stem cell (PBSC) transplantation for haematological malignancies. Strikingly, high-dose cytarabine and etoposide plus granulocyte colony stimulating factor (G-CSF) mobilized PBSC harvests from acute myeloid leukaemia (AML) patients containing the highest number of myeloid lin(neg)CD11c(pos) DC (mean: 7.04 x 106/kg, range: 1.46-19.67) which was 18.1-fold higher than in non-AML patients mobilized using chemotherapy (CT) regimens plus G-CSF. Clonality of purified lin(neg)CD11c(pos) DC from CT plus G-CSF mobilized AML patients (n = 8 ) was assessed using the human androgen-receptor locus methylation, disclosing a polyclonal pattern in five female patients. These cells displayed morphological and phenotypic features of myeloid DC precursors with expression of HLA-DR, HLA-ABC, CD86, CCR5 and CD54 molecules but lacking CD80, CD83, CD1a and CD40 antigens. Short-term culture with autologous leukaemic cell lysates plus tumour necrosis factor-alpha yielded maturated myeloid DC capable of triggering interleukin-2 and interferon-gamma production by autologous T-lymphocytes. These findings suggest that the use of post-remission CT and G-CSF as mobilizing regimen in AML patients generates PBSC containing high doses of polyclonal myeloid lin(neg)CD11c(pos) DC precursors, which could be used to design feasible immunotherapy protocols.     

Autologous blood stem cell transplantation for acute myeloblastic leukemia in first complete remission. Intensification therapy before transplantation does not prolong disease-free survival

BACKGROUND AND OBJECTIVE: To compare the clinical results of two consecutive therapeutic protocols including autologous blood stem cell transplantation (ABSCT) for patients with de novo acute myeloblastic leukemia (AML) in first complete remission (CR1). DESIGN AND METHODS: Between November 1989 and January 1997, 50 patients with AML in CR1 underwent ABSCT using two consecutive protocols. In the first one (Group A, 25 patients) peripheral blood stem cells (PBSC) were collected after induction and consolidation chemotherapy courses, and ABSCT was performed immediately thereafter. In the subsequent 25 patients (Group B), PBSC were collected after consolidation alone, and a further chemotherapy course with intermediate dose cytarabine (Ara-C 1 g/m2/12 h x3 days) and mitoxantrone (12 mg/m2/d x3 days) was administered as early intensification. The conditioning regimen consisted of busulfan (16 mg/kg) and cyclophosphamide (200 mg/kg) in every case. RESULTS: Hematopoietic engraftment was slightly quicker in Group B, with median times to reach 0.5 x 10(9) neutrophils/L and 20 x 10(9) platelets/L being 13 and 12 days in Group A and 12 and 11 days in Group B, respectively. There were three graft failures (8%) (2 in Group A and 1 in Group B) and three transplant-related deaths (8%) (2 in Group A and 1 in Group B). No significant differences were observed between the groups in terms of relapse (64% at 4-years in Group A and 81% in Group B). Likewise, the actuarial 4-year disease-free survival (DFS) was not significantly different between the two groups (32% v 18%). INTERPRETATION AND CONCLUSIONS: Our study confirms that AML patients in CR1 receiving ABSCT have rapid engraftment with low mortality. However, autologous transplants with PBSC collected after consolidation chemotherapy were still associated with a high rate of relapse (RR). This RR was not apparently reduced by the administration of intermediate dose Ara-C before transplantation.