How can we cure leukaemia?

High-dose chemotherapy in adult acute myeloid leukemia: rationale and results

Preclinical studies and retrospective evaluations of clinical trials of a number of cytotoxic drugs have provided a rationale for the use of high doses of chemotherapy in adults with acute myeloid leukemia (AML). To maximize cure and remission rates at an acceptable cost in toxicity, many schedules and combinations of dose-intensive chemotherapy have been tested in recent years in patients with de novo disease, cytosine arabinoside (Ara-C) being the most extensively evaluated drug. In this article we review the principal results of both randomized and non-controlled studies. Our analysis indicates that high-dose Ara-C (HIDAC) used during induction results is no substantial benefit relative to conventional doses of drug. On the other hand, consolidation with HIDAC is a major advance in the treatment of this disease. In fact, in individuals less than 60 years of age and a favorable or intermediate-risk karyotype, HIDAC-based regimens have resulted in survival estimates comparable to those of autologous or allogeneic bone marrow transplantation. Yet, the role of HIDAC is irrelevant in younger individuals with an unfavorable cytogenetic pattern and detrimental in patients greater than 60 years of age. Since recently new cytotoxic agents have expanded the armamentarium of antileukemic drugs, well conducted randomized trials of dose intensive chemotherapy still need to be performed to optimize schedules and combinations of drugs in patients with AML.

Minimally differentiated acute myeloid leukaemia (AML-M0): cytochemical, immunophenotypic and cytogenetic analysis of 19 cases

We describe our experience in the identification of 19 cases of AML-M0 categorized among 200 consecutive AML cases. Leukaemic cells from our cases were morphologically marked by agranular basophilic cytoplasm, finely dispersed chromatin and prominent nucleoli. In two cases heavily vacuolated and monocytoid-shaped blasts were also observed. Cytochemistry (MPO, SBB, alpha ANAE, alpha NBE, NASDCAE, AP, PAS) was negative in 14 cases, five cases expressing a very faint cytoplasmic positivity for alpha NBE (not exceeding 30% of the blasts) and alpha ANAE (not exceeding 41%) which was sodium fluoride resistant. In these five cases other monocytic markers (e.g. CD14) were not in favour of myelomonocytic differentiation. All the cases were anti-MPO positive at frequency > 10%. Phenotypic analysis also revealed myeloid features with all the patients having at least one myeloid antigen (CD13, CD33, CD15), Tdt was expressed in nine cases and CD7 in six cases. All cases but one were positive for CD34. Cytogenetic analysis, performed in 16 cases, showed no adequate growth in two cases and no consistent abnormality in four; among the remaining 10 cases no consistent abnormality was observed, the most common finding was trisomy 8 (two cases) and 4 (two cases) and aberrations of chromosomes 2, 3, 5, 7, 9, 12 and 21. No cases of (t9;22), Ph chromosome were observed. Interestingly three out of five patients with faint alpha NBE/alpha ANAE positivity relapsed as typical M4 (one case) or M5a (two cases).

Long-term results of autologous bone marrow transplantation in adult acute lymphoblastic leukemia

Autologous bone marrow transplantation (BMT) is widely performed in both adult and high-risk pediatric acute lymphoblastic leukemia (ALL). Nevertheless, there is still a lack of definitive data concerning its real effectiveness in prolonging the survival of these patients. Between 1984 and 1992, 20 ALL patients in first, second and third complete remission (CR) underwent autografting in the BMT Unit of the University of Milan. This series included 3 children in CR after one or more hematological relapses while all the other patients were adult. Autologous bone marrow was harvested during the same disease phase as that in which the autologous BMT was performed. The conditioning regimen included high-dose Ara-C, cyclophosphamide and TBI 1000 cGy. Successful engraftment occurred in all patients; no early deaths or deaths in CR were recorded, making disease-free survival and event-free survival (EFS) curves superimposable. The overall chance of EFS at 72 months was 41%: 57% for patients in first CR, 53% for patients autografted after one or more isolated meningeal relapse, 14% for patients autografted after one or more hematological relapse. The present data do not provide any evidence to support a role for autologous BMT in prolonging EFS in first CR ALL patients. Nevertheless, the results after meningeal relapse seem to be favourable when compared with the disappointing prospects of these patients after conventional chemotherapy. The EFS after hematological relapse revealed by this study does not significantly differ from that reported in the majority of other studies: the efficacy of autologous BMT in these ALL patients is doubtful.

Highly efficient elimination of Philadelphia leukemic cells by exposure to bcr/abl antisense oligodeoxynucleotides combined with mafosfamide

Synthetic oligodeoxynucleotides complementary to the break-point junction of bcr-abl transcripts selectively inhibit the proliferation of Philadelphia-positive leukemic cells, but residual leukemic cells persist in antisense oligodeoxynucleotides-treated cultures. Cyclophosphamide derivatives such as mafosfamide and 4-hydroperoxycyclophosphamide are used at high doses for purging of Philadelphia leukemic cells from marrows but such treatment can be associated with delayed engraftment and prolonged cytopenias. To develop a more effective procedure that might optimize the killing of leukemia cells and the sparing of normal hematopoietic progenitor cells, a 1:1 mixture of Philadelphia leukemic cells and normal bone marrow cells was exposed to a combination of a low dose of mafosfamide and bcr-abl antisense oligodeoxynucleotides and assayed for growth ability in clonogenic assays and in immunodeficient mice. Bcr-abl transcripts were not detected in residual colonies, and cytogenetic analysis of individual colonies revealed a normal karyotype. Normal but not leukemic hematopoietic colonies of human origin were also detected in marrows of immunodeficient mice 1 mo after injection of the treated cells. Our results indicate that a combination of a conventional chemotherapeutic agent and a tumor-specific antisense oligodeoxynucleotide is highly effective in killing leukemic cells and in sparing a much higher number of normal progenitor cells as compared with high-dose mafosfamide treatment. This offers the prospect of a novel and more selective ex vivo treatment of chronic myelogenous leukemia.

The management of recurrent acute myelogenous leukaemia at a single centre over a fifteen-year period

One hundred and sixty-two patients initially treated at St Bartholomew's Hospital between 1974 and 1988 developed recurrent acute myelogenous leukaemia (AML). In the majority, the intention was to administer intensive chemotherapy again; 22/162 were re-treated palliatively. A second complete remission (CR) was achieved in 50/126 (40%) evaluable patients. Several different regimens were employed over this time period; the treatment used was the only factor that correlated with achievement of second CR (P = 0.04). Ten of the 50 patients received myeloablative therapy with either allogeneic or autologous bone marrow transplantation in second CR. The median duration of second CR for those patients who did not proceed to intensive consolidation with bone marrow transplantation was 7 months. There was no correlation between second remission duration and age, or with the administration of either intensive or conventional consolidation therapy. The median survival from first recurrence for all patients was 4 months, increasing to only 5 1/2 months for those re-treated with chemotherapy and to 12 months for those patients in whom a second CR was achieved, confirming the very poor prognosis of these patients.

Intensive sequential post-induction therapy for adults with acute myelogenous leukemia in first remission: long-term follow-up and results

We designed a post-induction therapy including intensive sequential therapy with non-cross-resistant drugs in an effort to prolong disease-free survival (DFS) for adults with acute myelogenous leukemia. Forty-five patients entered this study and 33 of 35 patients entering complete remission received the post-induction therapy. With a median follow-up for survivors of 3.5 years from complete remission, the actuarial 5-year DFS was 46% +/- 19% (95% confidence interval). The five-year DFS for patients over 45 years of age was comparable to that for patients under 45 years of age (50% +/- 26% vs 47% +/- 28%). Furthermore, the actuarial 5-year DFS for patients who required two courses of induction therapy was comparable to that for patients who required only one course of induction therapy (45% +/- 29% vs 50% +/- 25%). The toxicity of post-induction therapy was tolerable and no patients died during complete remission.

Graft-versus-leukemia activity after bone marrow transplantation does not require graft-versus-host disease

Clinical data have suggested that graft-versus-host disease (GVHD) plays a crucial role in the antileukemic effects of bone marrow grafts. We investigated (a) whether bone marrow cells unable to induce GVHD can effect graft-versus-leukemia (GVL) activity and (b) whether such antileukemic capacity depends on the presence of T lymphocytes in the graft. Balb/c mice were inoculated with A20 cells, a B-cell lymphoma/leukemia of Balb/c origin. Four weeks after tumor inoculation the animals were lethally irradiated and received a bone marrow graft. Cells from (Balb/c x C57) F1 or (C3H x Balb/c) F1 hybrids were transplanted into parental-strain Balb/c mice. Since lymphocytes from F1 hybrids are unable to cause graft-versus-host reactivity against a parental-strain animal, we used this experimental setting to explore GVL effects in a GVHD-free system. In vitro incubation with monoclonal anti-Thy-1.2 antibody plus complement was used to eliminate Thy-1+ cells. After syngeneic transplantation, the death rate due to leukemia remained unchanged (91%) compared with that among untreated animals (86%). Following transplantation of F1 marrow cells of either (C57 x Balb/c) F1 or (C3H x Balb/c) F1 origin, death rates of 40% and 50% were observed; these were significantly lower. Depletion of Thy 1+ cells from bone marrow graft caused only a slight increase in the leukemic death rate after transplantation of bone marrow of (C57 x Balb/c) F1 hybrid origin (50%), but a high leukemic death rate was seen after transplantation of (C3H x Balb/c) F1 bone marrow (100%). Additional experiments with fully allogeneic, T-cell-depleted C57 bone marrow transplantation suggest an antileukemic effect that is comparable to that seen after transplantation of unmanipulated F1 bone marrow. Taken together, our results indicate that GVL activity can be dissociated from graft-versus-host reaction.

High remission rate in acute myeloblastic leukemia in children treated with high-dose methylprednisolone

Since the differentiating effect of high-dose methylprednisolone (HDMP) on myeloid leukemic cells has been shown in one of our patients with acute myeloblastic leukemia (AML-M4), 27 previously untreated children with AML were given HDMP (20-30 mg/kg per day) combined with cytosine arabinoside (Ara-C; 3 mg/kg) for the first 2 weeks of induction therapy. Marked clinical improvement was observed in all patients with the exception of one who died within 24 hours of the treatment. Enlarged liver and spleen (greater than 5 cm) became nonpalpable in 3 (37%) out of 8 and 5 (100%) out of 5 patients, respectively, and bone marrow blasts decreased below 5% in 7 patients (27%) within 2 wk of HDMP and Ara-C treatment. Adriamycin (1 mg/kg) was added 2 wk after initiation of induction therapy. Twenty-two (84.6%) of the 26 patients achieved complete remission, 3 (11.5%) had partial remission and no response was obtained in one. Treatment was well tolerated. The addition of HDMP as a differentiating and/or cytolytic agent to conventional anti-leukemic chemotherapy increased the complete remission rate and prolonged the duration of remission of our AML patients.

Etoposide in combination with intermediate dose cytosine arabinoside (ID ARA C) given with the intention of further myeloablative therapy for the treatment of refractory or recurrent hematological malignancy

Thirty-four patients with refractory or recurrent high grade non-Hodgkin's lymphoma (NHL) or acute leukemia were treated with a combination of etoposide, 100 mg/m2 daily, and ara C, 1 g/m2 twice daily, for 5 days (VPARAC). This therapy was given in the anticipation that remissions thus achieved would be 'consolidated' with myeloablative therapy supported by bone marrow transplantation (BMT). The complete remission rate (CR) in patients with NHL was 3/18 (17 per cent) with partial responses (PR) seen in a further four patients, giving an overall response rate of 39 per cent. Four patients (three in CR, one in PR) proceeded to the planned consolidation treatment. Complete remission was achieved in 2/8 (25 per cent) patients with acute myelogenous leukemia (AML) and in 2/8 patients with acute lymphoblastic leukemia (ALL). Three of these patients subsequently had myeloablative consolidation therapy with BMT. There were four treatment-related deaths (NHL, two; AML, one; ALL, one). In poor risk patients with high grade NHL and acute leukemia, VPARAC is an effective remission induction programme in 21 per cent of patients. Seven of the original 34 patients received the intended 'curative' therapy, of whom only four are alive and well 1 year later.

Autotransplants in acute leukaemia

The data we review indicate that in adults with ALL in first remission intensive chemotherapy and radiation given before a transplant is more effective in eradicating leukaemia than current chemotherapy. This is not so in adults with AML in first remission where more intensive therapy does not reduce the likelihood of relapse. Furthermore, leukaemia relapse because of re-infused leukaemia cells is an important issue in autotransplants for ALL. Whether re-infusing leukaemia cells would be important in AML were more effective pretransplant therapy developed is unknown. Presently, there appears to be little sense to test in vitro approaches to remove leukaemia cells in autotransplants for AML because efficacy cannot be evaluated. (A randomized trial is an exception but would not be expected to show a difference.) Another conclusion is that attempts to induce GVHD in autotransplant recipients, such as by using cyclosporine post-transplant (Jones et al, 1989), are more likely to succeed in AML than ALL since the impact of GVHD is substantially greater (Horowitz et al, 1990). However, the GVHD-related antileukaemia effect in AML is associated with chronic GVHD whereas cyclosporine treatment of autotransplant recipients results in acute GVHD. Also, attempts to separate clinical and antileukaemia effects of GVHD were unsuccessful (Sullivan et al, 1989). Another caution is that in AML we detected an immune antileukaemia effect distinct from GVHD (termed GVL) only after HLA-identical sibling transplants. Since GVL was absent in twins it is unlikely to operate after autotransplants. In summary, there is sense in studying autotransplants in adults with acute leukaemia in first remission. However, there are currently no convincing data that autotransplants are superior to current therapy. More intensive treatment seems effective in ALL; the focus should be on increasing the antileukaemia efficacy of pretransplant therapy and on attempts to remove leukaemia cells from the graft. In AML, there is no evidence that more intensive therapy is more effective. This problem needs resolution before evaluating attempts to remove leukaemia cells from the graft. The best place to test new pretransplant regimens is in twins and recipients of HLA-identical sibling transplants without GVHD. The data and ideas we review and discuss should be useful in planning clinical trials.

Autotransplants in leukemia: current state, future progress

Autotransplants in leukemia are controversial; their rationale and results have been questioned. Here we consider several issues central to this debate: (1) Are there convincing data to suggest that more intensive therapy increases cures? (2) Are results post-autotransplant a consequence of the transplant, or do they reflect subject-selection and time-to-treatment (time censoring) biases? (3) Does leukemia relapse after an autotransplant develop from persisting leukemia cells in the subject or the graft? (4) Do autotransplants using hematopoietic stem cells from different sources have distinct outcomes? (5) Are immune-mediated anti-leukemia mechanisms likely to prevent relapse after autotransplants? and (6) Can comparably intensive therapy be given without an autotransplant?

Clinicopathological features of acute undifferentiated leukaemia with a stem cell phenotype

Over a 4 1/2-year period, 141 patients with acute leukaemia had morphologic, immunophenotypic and cytochemical studies performed at King's College Hospital. Seven cases were noted to have blast cells which did not express myeloid or lymphoid antigens or cytochemical staining indicative of differentiation but were HLA DR and CD 34 positive. Based on these criteria we have used the term stem cell acute leukaemia to denote these patients. There were five women and two men with a median age of 61 years (16-86). Presentation marrows were heavily infiltrated with blasts (greater than 95% in 6/7) which were usually pleomorphic. Type 2 blasts. Auer rods and dysplastic features were absent. Two of six cases studied showed clonal karyotypic abnormalities. Four patients were treated with high dose chemotherapy. Three of these achieved a complete remission but relapsed at 3, 6 and 7 months respectively. The median survival of the group was 7 months (2-12). We conclude that the stem cell acute leukaemias are a distinct clinicomorphological group which appear to have a poor prognosis with conventional chemotherapy.

Successful adoptive immunotherapy of minimal residual disease after chemoradiotherapy and transplantation of bone marrow purged of leukaemia with mafosfamide

The effectiveness of adoptive immunotherapy in eliminating minimal residual disease in tumour-bearing mice after bone marrow transplantation was tested. This model mimics the human clinical condition when autologous bone marrow was purged ex vivo of leukaemia with mafosfamide or was not purged, and stored in liquid nitrogen before transplantation. Animals with minimal residual disease were prepared with marrow-ablative but leukaemia-noncurative doses of cyclophosphamide (CY) and total body irradiation followed by bone marrow transplantation. The next day after transplantation the recipients were injected with splenocytes immunized against the leukaemia cells (Imm-SPL) or monoclonal antibody (mAb). All the control mice died from leukaemia relapse, but 51% of purged bone marrow recipients, which received Imm-SPL, were cured. In similar conditions mAb did not exert a therapeutic effect. Imm-SPL were not able to eradicate minimal residual disease in the recipients of nonpurged bone marrow. Thus, in an animal model, we demonstrated that purging of bone marrow before grafting seems to be indispensable for successful adoptive immunotherapy of minimal residual disease (MRD) after autologous bone marrow transplantation.

Autotransplants in leukaemia

With bone marrow autotransplants, favourable results are reported in subjects with leukaemia in first and second remission but not in those with advanced disease. Whether autotransplants are equivalent or superior to other therapies such as chemotherapy and allogeneic transplants is uncertain, since prospective trials are not reported and data analysis is confounded by selection of subjects and time-censoring. Major problems of autotransplants include difficulty in eradicating leukaemia in the subject, lack of the graft-versus-leukaemia effect associated with allotransplants, and reinfusion of leukaemia cells.