Clinical studies of ABMT in acute myeloid leukaemia

Differential effects of IL-2 incubation on hematopoietic potential of autologous bone marrow and mobilized PBSC from patients with hematologic malignancies

Culturing of hematopoietic progenitor cells for 24 h with IL-2 generates cytotoxic effector cells that mediate in vitro and possibly in vivo antitumor activity. We examined the effect of IL-2 incubation on progenitor cells from 24 patients with hematologic malignancies using paired autologous bone marrow (ABM) and PBSC to determine differences in hematopoietic potential. Cells were cryopreserved and stored in liquid nitrogen until conditioning therapy was completed. After thawing, cells were incubated with IL-2 for 24 h at 37 degrees C. Paired samples of ABM and PBSC from the same patient were analyzed for nucleated and mononuclear cell number, CD34 antigen expression, and colony-forming unit (CFU) activity before and after IL-2 incubation. There was a significant decrease in the average number of mononuclear cells (MNC) (x10(8)/kg) (<0.001) and CD34+ cells (x10(6)/kg) (0.006) from both ABM and PBSC after 24 h IL-2 culture (ABM MNC: 0.6+/-0.1 vs. 0.4+/-0.0, p = <0.001; PBSC MNC: 4.4+/-0.5 vs. 3.7+/-0.4, p = 0.03; ABM CD34+: 2.4+/-0.5 vs. 1.3+/-0.3, p = <0.001; PBSC CD34+: 6.6+/-1.8 vs. 5.0+/-1.2, p = 0.05). However, whereas ABM CFU/10(5) MNC plated (269.3+/-47.2 vs. 385.6+/-70.6) were significantly increased (p = 0.005), there was no change in PBSC CFU (271.0+/-47.2 vs. 257.3+/-48.5). The mean plating efficiency (%) of ABM CD34+ cells was markedly increased after IL-2 incubation (10.1+/-3.3 vs. 19.0+/-7.2, p = 0.04), although it was lower than that of PBSC CD34+ cells, which did not change significantly in culture (29.4+/-5.5 vs. 36.0+/-6.5). Additional work is in progress to determine the cause and significance of the enhanced plating efficiency of the ABM progenitor cells.

Immunomodulation following chemotherapy

In the last decade, immunomodulation has emerged as a mode of therapy capable of mediating the regression of cancer in some patients. This article reviews our experience with immunomodulation following transplant and non-transplant chemotherapy. We used interferon and cyclosporine A following conventional chemotherapy in a non-transplant setting for a B16 melanoma in a murine model. This combination generated cells with MHC-unrestricted cytotoxicity. We have also used immunotherapy in the transplant setting with IL-2 activated PBSC in patients with breast cancer. Of the 28 patients treated, 20 developed GVHD and the average time to reconstitution was 12 days (comparable to a control group). This article also raises the possibility of extending immunomodulation to breast cancer patients in the nontransplant setting to induce an antitumor immune response following cytoreductive chemotherapy.

Autologous bone marrow transplant in the treatment of acute leukaemia

For a minority of patients with acute leukaemia, usually in children and predominantly with acute lymphoblastic leukaemia, existing chemotherapy protocols are curative. For a minority of the remaining group myeloablative chemoradiotherapy supported by allogeneic marrow from an HLA-matched donor can cure the disease. Major efforts are being made to free the potential benefit of this approach from the limitations imposed by the associated immune-biological complications, and limited donor availability. In the last decade the resurgence of autologous transplantation in remission has been a major new source of hope for further progress. Many groups have produced encouraging results, which now that they have substantial follow-up, suggest that this approach is altering the normal pattern of relapse. Almost all the experience, however, while producing consistent results, at least in AML, is anecdotal. The possibility of selection bias, particularly by the time-censoring effect, cannot be excluded, and prospective controlled trials are needed. The data available suggest which investigations could be expected to yield clear results. Other questions, particularly whether or not to purge the marrow, are only practical to investigate in well-defined patient subgroups. The opportunity to identify predictive parameters in this new clinical setting, using the more powerful techniques now becoming available should not be missed. National and international trials now in progress will yield crucial data in the next 2 or 3 years.

Comparison of allogeneic or autologous bone marrow transplantation and chemotherapy in patients with acute myeloid leukaemia in first remission: a prospective controlled trial

Eighty-five adult patients under the age of 50 years with acute myeloid leukaemia (AML) were entered into a prospective controlled study conducted to compare the effectiveness of allogeneic or autologous bone marrow transplantation and intensive chemotherapy for patients in first complete remission. Sixty-one patients (72%) achieved complete remission then received a consolidation treatment. After consolidation, 58 patients who were still in remission were assigned to three different therapeutic modalities. Fifty-two patients were evaluable: 20 patients who had an HLA-identical sibling donor underwent allogeneic bone marrow transplantation within 3 months after achievement of complete remission; the other 32 patients were randomized to receive autologous bone marrow transplantation or intensive sequential chemotherapy. The actuarial risk of relapse at 3 years was 18% for the allogeneic patients, 50% for the autologous patients and 83% in the chemotherapy group. The difference was highly significant (P less than 0.0002). The disease-free survival was respectively 66% (95% confidence interval 41-85%), 41% (95% confidence interval 16-66%) and 16% (95% confidence interval 0-31%) (P less than 0.004). We conclude that allogeneic bone marrow transplantation is presently the best therapeutic approach for patients with AML in first complete remission.

Haematological recovery following high-dose cyclophosphamide with autologous bone marrow transplantation

A total of 31 patients with previously untreated small-cell carcinoma of the lung were treated with very-high-dose cyclophosphamide, using autologous bone marrow transplantation (ABMT) to assist haematological recovery. The period of neutropenia was shorter with 40 mg/kg cyclophosphamide x 4 (7 patients) than when the dose of cyclophosphamide was increased to 50 mg/kg x 4 (11 patients), despite ABMT 2 days after chemotherapy in each group. In all, 13 patients were treated with 50 mg/kg cyclophosphamide x 4, with infusion of bone marrow delayed to day 4, 6 or 8 after chemotherapy to determine the contribution of ABMT to haematological recovery. The period of neutropaenia was increased when marrow was returned 6 days following chemotherapy, confirming that ABMT contributed to haematological recovery after this schedule of treatment. A total of 11 patients had a second cycle of 50 mg/kg cyclophosphamide x 4 after recovery from the first cycle of high-dose chemotherapy. The period of myelosuppression was greater with the second cycle of chemotherapy, although ABMT was carried out during both cycles. The results show that ABMT contributes to haematological recovery when the dose of cyclophosphamide is high enough to produce prolonged hypoplasia. The increased myelosuppression observed after a second high-dose treatment in spite of ABMT suggests either that both transplanted and endogenous marrow activity contribute to recovery of myelopoiesis or that there is residual damage to marrow stroma after the first cycle of treatment. The data indicate the necessity of carefully assessing the role of ABMT in haematological recovery with high-dose chemotherapy regimens.

Autologous bone marrow transplantation in children

Autologous bone marrow transplantation is a procedure that allows for the delivery of high doses of chemotherapy and radiation to treat pediatric malignancies. There have been many studies showing a dose-response curve for many of the drugs that have been used for cytoreductive therapy in autologous bone marrow transplantation. These dosage ranges are achievable in many of the preparative regimens used in autologous bone marrow transplantation. The results in neuroblastoma, Hodgkin's disease, non-Hodgkin's lymphoma, Ewing's sarcoma, rhabdomyosarcoma, osseous sarcoma, other soft tissue sarcomas, and acute leukemias (acute lymphoblastic leukemia and acute non-lymphoblastic leukemia) are reviewed. The question of purging of bone marrow during autologous bone marrow transplantation is addressed. The different techniques of purging are reviewed and the advantages and disadvantages of each are discussed. Finally, new areas of treatment and future directions of autologous bone marrow transplantation are addressed.

Heterogeneity among the acute nonlymphocytic leukemias: value of immunophenotype for diagnosis, prognosis, and therapy

Immunophenotyping of acute nonlymphocytic leukemia has confirmed previous observations on the heterogeneity of this disease. The lack of leukemia-specific monoclonal antibodies as well as antibodies reactive with early myeloid cells is reflected in poor correlation of morphologically and cytochemically defined FAB classes with the immunophenotype of the leukemic cells. Possible exceptions are the microgranular variant of FAB-M3, megakaryocytic leukemia (FAB-M7), and early erythroid leukemias (FAB-M6). The use of antibody panels can alleviate the differential diagnosis of acute lymphoid and myeloid leukemias, especially those occurring in infants, and the discrimination of FAB-L2 and FAB-M1. Also, the immunophenotyping of presumptive hybrid leukemias can help to resolve the many questions about these leukemias with a particularly poor prognosis. The challenge for multiinstitutional groups is to define those clinically relevant subgroups of acute nonlymphocytic leukemia in children that have general acceptance and could provide the basis for new treatment strategies.

Prospects for cure in leukaemia

Patients with acute leukaemia have normal or near normal numbers of haemopoietic stem cells in their marrow at diagnosis. Remission is achieved when the administration of cytotoxic drugs eradicates the bulk of the leukaemic population while sparing normal haemopoiesis. The mechanism by which chemotherapy seems to act in this selective manner is essentially unknown. Nevertheless, remission rates of 80-95% can be achieved in children and in 50-80% of adults with acute leukaemia. Attempts to cure patients in remission may entail either "continuing curative chemotherapy" or "supralethal" doses of chemoradiotherapy followed by autologous or allogeneic bone marrow transplantation. The relative merits of these different methods remain highly controversial but chemotherapy is usually the preferred method of continuing treatment for children with acute lymphoblastic leukaemia in first remission; and allogeneic transplantation is recommended for younger adults with acute myeloid leukaemia who have suitable HLA-identical sibling donors. The role of autografting is still experimental. Patients with chronic myeloid leukaemia can achieve long term remission and probably cure following allogeneic bone marrow transplantation but the resultant risks of mortality are still appreciable. Chronic lymphocytic leukaemia currently remains incurable.

Comparison of the sensitivity of normal and leukaemic myeloid progenitors to in-vitro incubation with cytotoxic drugs: a study of pharmacological purging

The sensitivity of myeloid leukaemic colony forming cells (AML-CFC), to five cytotoxic drugs has been compared in two culture systems with the sensitivity of normal myeloid progenitor cells (GM-CFC). No increased sensitivity was found for AML-CFC to any of the chemotherapeutic agents studied. AML-CFC were significantly less sensitive than normal GM-CFC to mafosfamide at the doses commonly used to purge bone marrow autografts. It is suggested that AML cells probably display similar sensitivity to cytotoxic agents as normal myelopoietic cells at a similar stage of differentiation. Hence complete elimination of the leukemic clone by pharmacological purging may be incompatible with bone marrow re-engraftment. We conclude that purging AML autografts with any of the agents examined has little scientific basis.