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Failure of purged autologous bone marrow transplantation in high risk acute lymphoblastic leukaemia in first complete remission.

Patients in first remission of acute lymphoblastic leukaemia (ALL) considered to be at high risk of relapse were offered autologous bone marrow transplantation (ABMT) using purged marrow as a therapeutic alternative to cranial irradiation and maintenance chemotherapy. Twenty-seven bone marrows taken in remission, were purged using monoclonal antibodies (anti CD7 for T lineage and anti CD10 and/or anti CD19 for B lineage leukaemias) plus rabbit complement. Retrospective analysis of 19 purged marrows by immunophenotyping or immunoglobulin gene rearrangement studies demonstrated no evidence of disease. Engraftment was seen in 26 of the patients. No correlation was found between the numbers of infused nucleated cells or colony forming units-granulocyte-macrophage (CFU-GM) and subsequent engraftment kinetics. The actuarial disease-free survival (DFS) is 32% at 7 years (median follow-up 3.4 years). There were two transplant related deaths (actuarial risk 8%); the main cause of treatment failure has been disease recurrence with an overall actuarial risk of 67%; 76% for T-ALL (five of nine), 62% for common ALL (five of 10), two of five pre B and none of three patients with B-ALL. In these 27 high risk patients in vitro purging of remission marrow as part of ABMT appears not to improve patient outcome, although confirmation of this would require a randomized trial.

Adolescent↗

Purging autologous bone marrow with monoclonal antibodies for transplantation in acute myelogenous leukemia.

Myeloablative chemotherapy followed by allogeneic bone marrow rescue is considered curative therapy and offers an alternative approach to consolidate patients with acute myelogenous leukemia who achieve a first complete remission after standard induction chemotherapy. In patients transplanted during second or third complete remission, allogeneic transplantation can also be curative, although there is lower relapse-free survival. Despite the success of this treatment modality, only 10-20% of patients will be eligible to receive an allogeneic transplantation due to advanced age or lack of an HLA-matched donor. In this situation, autologous bone marrow transplantation allows therapy of comparable intensity to be administered with less morbidity and mortality due to the lack of graft-versus-host disease. In contrast to allografts, remission autografts may harbor residual occult malignant cells unable to be grossly detected. The infusion of these malignant cells following myeloablative therapy can contribute to leukemia relapse. Various in vitro approaches to 'purge' occult malignant leukemia cells from remission marrows have been developed. The two techniques that have been studied in preclinical and clinical trials include pharmacological and monoclonal antibody-mediated methods. The efficacy of using the latter to purge autografts compared with the use of unpurged autografts in patients with acute myelogenous leukemia undergoing autologous bone marrow transplantation is currently the focus of a prospective multicenter trial.

Antibodies, Monoclonal↗

Graft purging in autologous bone marrow transplantation: a promise not quite fulfilled.

Clonogenic tumor cells contained within hematopoietic stem cell (HPC) grafts may contribute to relapse following autologous transplantation. Graft purging involves either in vivo or ex vivo HPC manipulation in order to reduce the level of tumor cell contamination. Some phase II trials suggest that patients who receive purged products may have a superior transplant outcome. Phase I trials demonstrate the feasibility of purging methods including ex vivo graft incubation with chemotherapeutic drugs, monoclonal antibodies and complement, and CD34+ cell selection. A phase II trial in follicular non-Hodgkin's lymphoma demonstrates that patients who receive HPC products purged negative for bcl-2 gene rearrangements have a superior outcome, compared with patients who receive polymerase chain reaction (PCR)-positive products. This finding, however, has not been confirmed in a randomized trial. HPC purging has demonstrated no benefit in a phase III trial in myeloma. Phase II trials in acute myelogenous leukemia show comparable outcomes for patients who receive either purged or unpurged HPC grafts. Limitations of purging include possible progenitor cell loss, delayed engraftment, and qualitative immune defects following transplant. Data to justify routine use of HPC graft purging are insufficient. Phase I and II data support development of phase III trials of both in vivo and in vitro purging methods.

Antibodies, Monoclonal↗

Role of myeloablative therapy in improved outcome for high risk neuroblastoma: review of recent Children's Cancer Group results.

The use of new strategies for dose intensification using peripheral blood stem cell or autologous purged bone marrow rescue has raised expectations for cure in advanced neuroblastoma, although conflicting reports exist regarding the efficacy of these approaches. Using risk groups based on both biological and clinical staging, the Children's Cancer Group (CCG) has conducted a series of pilot studies to test new induction, consolidation and myeloablative regimens to attempt to improve outcome. We summarise below the outcome and prognostic factor analysis for the pilot chemotherapy trial, CCG-(CCG-321P2), and the use of high dose myeloablative chemoradiotherapy with allogeneic (CCG-321P1) or autologous purged bone marrow rescue (CCG-321P3) for high risk neuroblastoma patients who were progression-free at the end of induction chemotherapy. After autologous bone marrow transplantation (ABMT), progression-free survival (PFS) at 4 years was 38% (median follow-up 4 years). Prognostic factors for relapse after ABMT included pre-BMT disease status, bone marrow tumour content at harvest, extent of primary resection at diagnosis, and time to ABMT. MYCN amplification, age, stage, and pre-BMT myeloablative regimen were not significant. Allogeneic BMT did not have a better outcome than ABMT. In a retrospective, non-randomised comparison of ABMT and chemotherapy, there was a significant difference in PFS for stage IV patients. High risk subgroups possibly benefiting from ABMT could be identified, including those with tumour MYCN amplification, over 2 years at diagnosis, and those not in complete remission at the end of induction. A randomised prospective trial comparing myeloablative therapy with ABMT to continuous infusion consolidation chemotherapy is currently underway in CCG to determine the relative benefit.

Adolescent↗

Autologous bone marrow transplantation with marrow purged by mafosfamide in seven patients with myelodysplastic syndromes in transformation (AML-MDS): a pilot study.

Seven patients with acute myeloblastic leukemia (AML) occurring on myelodysplastic syndromes (MDS) were consolidated while in complete remission (CR) by autologous bone marrow transplantation (ABMT) with a marrow purged in vitro by mafosfamide. The median age of population was 44 years (range 39-55). MDS FAB diagnosis was established before progression to AML in five patients: refractory anaemia with excess of blast (RAEB) in three patients, RAEB in transformation (RAEB-t) in one patient, and chronic myelomonocytic leukemia (CMML) in one patient. In the remaining two patients, the diagnosis of MDS (as a secondary malignancy in one) was made retrospectively at time of overt AML. Three out the seven patients had karyotypic abnormalities. The median interval between the obtention of CR and ABMT was 7 months (range 6-18). One patient died from transplant related toxicity. Engraftment occurred at a median of 41 days (range 27-60), for white blood cells (> 10(9)/l) and 120 days (range 60-180) for platelets (> 50 x 10(9)/l). Four patients relapsed at 2.5, 6.8, and 25 months post-ABMT. Two patients are alive and well at 10 and 28 months, respectively. ABMT with marrow purged by mafosfamide is feasible in patients with AML following MDS with a prospect of cure. However, further studies are needed to assess the real value of this approach.

Adult↗

Lymphokine-activated killer (LAK) cell purging of bone marrow.

The in vitro incubation of NK cells with the lymphokine IL-2 stimulates the development of a population of activated cytotoxic lymphocytes (LAK cells). These activated cells have the capacity to recognize and kill a wide range of neoplastic cells. The cytotoxic activity of LAK cells does not appear to be directed against normal, non-neoplastic cells and we have recently examined the potential for using LAK cells as a method of purging bone marrow for autologous transplantation in patients with widespread neoplastic diseases. We have utilized an experimental system consisting of the incubation of LAK cells from inbred F344 rats and normal bone marrow and demonstrated that this procedure does not interfere with the ability of the treated bone marrow to reconstitute lethally-conditioned recipients. The frequency and rate of reconstitution is the same in treatment and control groups, including incubation periods that extend up to 18 hours. When RNK-16 leukemia cell line (a spontaneous large granular lymphocyte leukemia that is syngeneic to the F344 strain) is added to the incubation mixture, the LAK cells have the ability in vitro to recognize the neoplastic cells and prevent the transmission of the leukemia to naive animals following bone marrow transplantation. As expected from the in vitro LAK cytotoxic activity, these activated cells are capable of recognizing and eliminating a variety of neoplasms. To date we have tested three different hematopoietic tumor lines derived from the F344 strain and one that was induced in an unrelated BN strain. In each case, the F344 LAK cells demonstrated an ability to prevent the transmission of a fatal leukemia and significantly prolong the survival of animals that had received larger numbers of neoplastic cells. The tumor lines examined included the RNK-16 line (NK cells), the Dunning leukemia (monocyte-lymphoblastic leukemia), a T-lymphocyte lymphoma and the acute myelogenous leukemia of BN rats (BN AML). Comparison of the results of these purging experiments to those seen when control animals are injected with graded doses of the individual tumors indicate that the LAK cells are eliminating approximately 2-3 logs of neoplastic cells. The ability of LAK cells to kill a wide range of tumors without damage to the ability of the recipient stem cells to reconstitute the bone marrow may allow for an important application for this type of purging technique in patients with neoplasms for which specific immunological or chemical therapies do not exist.

Animals↗

Hematological recovery after autologous bone marrow transplantation in acute leukemia: predictive factors.

The kinetics of hematological recovery after autologous marrow transplantation have been studied in 70 patients with acute leukemia (38 acute nonlymphoblastic leukemia [ANNL] and 32 acute lymphoblastic leukemia [ALL]). The incidence of graft failure in this group was 3.2%, and a persistent severe thrombocytopenia was observed in 24% of the cases. Variables influencing engraftment have been studied using univariate and multivariate statistical analysis. Analysis of the entire group showed a correlation between graft colony-forming unit granulocyte-macrophage (CFU-GM) content and granulocyte recovery (p < 0.001). Marrow purging was associated with a delayed engraftment (p < 0.001). In ANLL patients, we found that high cummulated AraC doses before marrow cryopreservation correlated with poor granulocyte recovery after marrow infusion (p < 0.002). Platelet recovery was essentially affected by age, with shorter thrombocytopenia periods in younger patients (p < 0.001). Finally, excluding autotransplants with purged marrows, ALL patients showed better platelet recoveries than ANLL patients (p < 0.005). These findings will be useful to evaluate the risk of delayed engraftment after autologous bone marrow transplantation (ABMT) in patients with acute leukemia.

Acute Disease↗

Immunomagnetic purging of bone marrow: a model for negative cell selection.

Many in vitro techniques have been developed for removing cancer cells from the marrow of patients who are to undergo autologous bone marrow transplantation (ABMT). These purging techniques can be classified as immunological or pharmacological. The immunomagnetic technique has been widely used in neuroblastoma patients. It depends on an interaction between target neuroblastoma cells in the marrow and a complex of specific monoclonal antibodies and magnetized microspheres, the target cells being selectively removed by passage through a magnetic field. Laboratory studies with neuroblastoma and acute lymphoblastic leukemia cells have shown the high efficiency of this technique in selectively removing cancer cells while retaining adequate numbers of normal hematopoietic cells for subsequent reinfusion into the patient. Clinical studies in several hundred neuroblastoma patients, as well as small numbers of acute lymphoblastic leukemia, breast cancer, and myeloma patients, suggest that this is a clinically safe and effective technique. However, no clinical trial has been conducted comparing ABMT with and without in vitro marrow purging. Until such time, we will regard immunomagnetic purging as "standard of care" for neuroblastoma patients receiving ABMT.

Bone Marrow↗

Successful engraftment after autologous transplantation of 10-day cultured bone marrow activated by interleukin 2 in patients with acute lymphoblastic leukemia.

Disease recurrence remains the major problem in autologous bone marrow transplantation (BMT) for hematologic malignancies. To improve the therapeutic efficiency of autologous BMT, we investigated the use of autologous marrow activated in vitro with interleukin 2 (IL-2) to generate killer cells for in vivo purging. A feasibility trial was initiated in 5 patients with poor prognosis acute lymphoblastic leukemia, who were transplanted, after marrow ablative therapy, with autologous marrow cultured for 10 days with 10(3) units of IL-2/ml. A highly significant increase in NK activity and an induction of LAK activity were observed after incubation. Patients received 0.64 to 1.56 X 10(8) cultured BM cells/kg and 1.87 to 44.8 x 10(4) CFU-GM/kg. Four patients engrafted and achieved granulocyte counts > 0.5 x 10(9)/l on days 35, 24, 36 and 22 after transplant. Three of these patients showed platelet recovery to > 50 x10(9)/l on days 25, 42 and 40 after transplant. One patient remained thrombocytopenic until relapse. One patient died on day 12 after transplant. This study demonstrates that cultured BM activated with IL-2 can be used successfully for hematological rescue in the clinical setting.

Bone Marrow↗

Overview of autologous stem cell transplantation.

There has been a dramatic increase in the number of autologous peripheral blood stem cell transplants over the last decade. Faster recovery of cell counts, lesser transplant morbidity, shorter hospital stay and reduced cost compared with marrow autografts have been the main advantages of autologous peripheral blood cell over marrow transplants. In this paper we attempt to review the advances in the biology and mobilization of stem cells, and focus on clinical results of autologous peripheral stem cell and marrow transplants for disease specific sites such as breast cancer, myeloma, autoimmune diseases, germ cell tumors, the acute and chronic leukemias, the non-Hodgkin's lymphomas and Hodgkin's disease. We also discuss transplant related complications, gene therapy and the different methods of purging. This review was intended for autologous peripheral stem cell transplants, however, unavoidably, it also discusses autologous marrow transplantation and aspects common to both procedures.

Bone Marrow Purging↗