Philadelphia-positive metaphases in the marrow after bone marrow transplantation for chronic granulocytic leukemia

Graft-vs.-malignancy with allogeneic blood stem cell transplantation: a potential primary treatment modality

The high-dose chemotherapy and radiation typically used as the preparative regimen for bone marrow transplantation produces considerable morbidity and mortality. An alternative strategy is to utilize a low-dose, non-myeloablative, preparative regimen designed not to eradicate the malignancy, but to provide sufficient immunosuppression to achieve engraftment of an allogeneic hematopoietic graft and allow subsequent development of a graft-vs.-malignancy effect. We studied this approach in patients who were ineligible for standard myeloablative preparative regimens because of advanced age or comorbidities and demonstrated that purine analog (fludarabine or 2-CDA) containing non-myeloablative chemotherapy allows engraftment of HLA-compatible hematopoietic progenitor cells, and extended remissions were observed in approximately half of chemosensitive patients with recurrent AML or CML. Patients with CLL or lymphoma have been effectively treated using a non-myeloablative regimen of fludarabine/cyclophosphamide of fludarabine, cytarabine, cisplatin. This chemotherapy is known to be non-myeloablative and mixed chimerism was anticipated. All patients with engraftment have responded and 67% have achieved complete remission. Maximal responses are slow to develop and occur gradually over a period of several months to one year. Long-term efficacy must still be determined and controlled trials are necessary comparing this approach with alternative therapies as well as standard transplantation regimens.

Allogeneic hematopoietic transplantation as adoptive immunotherapy. Induction of graft-versus-malignancy as primary therapy

An immune-mediated graft-versus-malignancy effect is important to prevent relapse after allogeneic bone marrow transplant for a range of hematologic malignancies and potentially some solid tumors. Graft-versus-leukemia (GVL) effects as seen in response to donor lymphocyte infusions have been most prominent against indolent malignancies including chronic myelogenous leukemia, chronic lymphocytic leukemia, and low-grade lymphoma. Acute myelogenous leukemia and multiple myeloma may also respond. An alternative strategy for allogeneic transplantation is to avoid the toxicity of high-dose chemoradiotherapy and use a relatively nontoxic, nonablative preparative regimen to achieve engraftment, allowing subsequent infusion of additional donor lymphocytes to mediate GVL. Fludarabine-based nonablative chemotherapy agents, using standard dose combinations, produce moderate myelosuppression but are sufficiently immunosuppressive to allow engraftment of an allogeneic hematopoietic transplant and generation of graft-versus-malignancy effects.

Clinical significance of bcr-abl gene rearrangement detected by the polymerase chain reaction after allogeneic bone marrow transplantation in chronic myelogenous leukemia

Although serial detection of bcr-abl positive cells by PCR appears able to identify distinct patient groups with different risks of relapse following BMT, there remain many unanswered questions regarding the clinical utility and biological significance of PCR detectable cells in this disease. Many of the studies summarized have conflicting results and the influence of various clinical parameters which are known to affect the risk of relapse post-BMT has not yet been consistently associated with the ability to detect bcr-abl positive cells by PCR. These clinical parameters include GVHD, T-cell depletion and intensity of immunosuppression following BMT. Prospective studies with larger patient numbers will be necessary to define the impact of these factors in PCR status and relapse. The answers to all these questions will increase our understanding of the biology of chronic myelogenous leukemia and help provide more effective therapies for the future.

Increased risk of relapse in patients with chronic myelogenous leukemia given T-cell depleted marrow compared to methotrexate combined with cyclosporin or monotherapy for the prevention of graft-versus-host disease

Fifty-two patients with chronic myelogenous leukemia (CML) who underwent bone marrow transplantation (BMT) at Huddinge Hospital were analyzed retrospectively regarding type of graft-versus-host disease (GvHD) prophylaxis. With T-cell depletion (TCD) (n = 13) the incidence of grade II-IV acute GvHD was 8% compared to 27% among patients given short course methotrexate (MTX) + cyclosporin (CSA) (n = 23) (ns) and 60% in patients who received MTX or CSA alone (n = 16) (p = 0.006 vs TCD and 0.03 vs MTX + CSA). The incidence of chronic GvHD was 56%, 31% and 75%, in the three groups, respectively (p = 0.02 combination vs monotherapy). Probability of relapse differed significantly, with most relapses in the TCD group, 62% compared to 20% in the MTX + CSA group (p = 0.02) and no relapse in the monotherapy group (p = 0.01 TCD vs monotherapy). Patient survival at 6 years was 54%, 59% and 38%, in the three groups, respectively (ns). Relapse-free survival was 23% in the TCD group, 55% in the combination group (p = 0.06) and 38% in the monotherapy group (ns). We conclude that TCD in patients with CML is correlated with an increased risk of relapse and a tendency towards a decreased long-term relapse-free survival compared to patients receiving other kind of GvHD prophylaxis.

Karyotype at relapse following allogeneic bone marrow transplantation for chronic myelogenous leukemia

Eighty-four patients underwent allogeneic or syngeneic bone marrow transplantation as therapy for chronic myelogenous leukemia (CML) during a 5-year period at The Johns Hopkins Oncology Center. We describe the karyotype at relapse in 19 patients who were Ph chromosome positive (Ph+) at diagnosis. Eighty-four percent of patients demonstrated clonal and/or nonclonal chromosome abnormalities in addition to the t(9;22)(q34;q11) at first detection of relapse or later during relapse. These abnormalities included: Ph plus additional clonal abnormalities (three patients), Ph plus nonclonal abnormalities (five patients), Ph plus additional clonal and nonclonal abnormalities (eight patients). Three patients had only the original Ph+ clone. The additional chromosome abnormalities were primarily structural, and entirely different from those most frequently observed during karyotypic evolution in conventionally treated CML. Chromosome 1 was most frequently involved, with 1q32 being the location of three clonal and two nonclonal abnormalities. Other sites included 6p21-22 (the site of two clonal abnormalities), 7p21-22, and 10q21 (the site of two clonal and one nonclonal abnormality each). Chromosomes 5 and 7q, regions of frequent involvement in acute nonlymphocytic leukemia that follows chemotherapy for other malignancies, were infrequently involved. The clinical significance of these additional abnormalities remains undetermined at this time.

Cytogenetic events after bone marrow transplantation for Philadelphia chromosome positive chronic myeloid leukemia

Allogeneic bone marrow transplantation is the only way to cure patients with Ph1+ chronic myeloid leukemia. It is commonly assumed that, in order to obtain a cure for the patients, the leukemic clone must be completely destroyed by the conditioning treatment and the donor's bone marrow must repopulate the hemopoietic niches leading to a "complete chimera". However, cytogenetic analyses, supported by molecular ones, indicate that Ph1+ cells, far from being completely destroyed by chemo-radiotherapy may persist for a long time, probably in the majority of the patients. As demonstrated by the outcome of patients receiving T-cell depleted marrow, immune mechanisms must be involved in controlling and progressively reducing the size of the residual leukemic clone. Furthermore, immunodulating therapeutic strategies, represented by cyclosporin-A discontinuation or alpha interferon treatment, may successfully reduce the Ph1+ cell population even after a full relapse.

Spontaneous complete remission of chronic myeloid leukaemia following haematological relapse after allogeneic bone marrow transplantation

A 31-year-old woman with Philadelphia (Ph) chromosome-positive chronic myeloid leukaemia (CML) underwent allogenic bone marrow transplantation during accelerated phase. Non-T-cell-depleted marrow from a male sibling mismatched at one Class 2 histocompatibility locus was infused after conditioning with total body irradiation and intravenous cyclophosphamide. Cyclosporin and methotrexate were given for prevention of graft-versus-host disease (GVHD). Prompt engraftment occurred with donor karyotype cells, followed by transient moderate acute GVHD. However, by day 60 after BMT, haematological relapse occurred with increasing splenomegaly, leucocytosis, increasing marrow fibrosis, and cytogenetic mosaicism, consisting of 47% donor metaphases with 53% Ph-positive host metaphases, some containing additional structural changes. Thirty days later further cytogenetic progression was evident. A slowly progressive fungal pneumonia concurrently present was treated with intravenous amphotericin and gradual reduction of cyclosporin. Subsequently, without further cytotoxic chemotherapy, pancytopenia and bone marrow hypoplasia developed, and on day 144 only donor karyotype marrow cells were seen. Chromosomes have remained of donor type on subsequent occasions, and the patient has a normal performance status 25 months after BMT. The patient's course illustrates that factors operating after allogeneic BMT contribute to longterm control of CML. The factors potentially responsible for this spontaneous remission, after early relapse, are discussed.

Detection of residual BCR/ABL transcripts in chronic myeloid leukaemia patients in complete remission using the polymerase chain reaction and nested primers

We sought evidence of BCR/ABL transcripts in the peripheral blood of nine CML patients in complete clinical and cytogenetic remission after treatment by bone marrow transplantation (BMT) or interferon and in one patient who entered spontaneous remission. Six patients were investigated at different times during their follow-up. We compared results obtained with the polymerase chain reaction (PCR) using (a) a single-stage PCR comprising 30 cycles of amplification with selected oligomers, and (b) a two-stage procedure in which the reaction product from the first stage was subjected to a further 30 cycles with nested amplimers. Special care was taken to assess contamination, including for each patient simultaneous co-extraction of a negative control. Blood cells from all patients showed no evidence of BCR/ABL transcripts in the one-stage PCR but 9/17 specimens were positive in the two-stage procedure. Patients in complete remission for a long time (greater than 2 years) appeared negative. These results serve in part to explain the discordant findings reported in other studies and emphasize the importance of carefully selecting the technical conditions most likely to give results that are prognostically relevant for individual patients.

Slow evolution of chronic myeloid leukaemia relapsing after BMT with T-cell depleted donor marrow

Thirty-three patients with Philadelphia positive (Ph+) chronic myeloid leukaemia (CML) treated in chronic phase by bone marrow transplantation (BMT) with T-cell depleted HLA-identical sibling marrow were evaluable for relapse at a median follow up of 41 months (range 16-59 months). Twenty-six (78%) had Ph+ marrow metaphases demonstrated at some time post BMT. The subsequent pattern of disease was variable. In 15 of these cases haematological relapse occurred within 24 months of BMT. Four patients proceeded to haematological relapse more slowly. Seven patients had only cytogenetic evidence of relapse. Of the 19 patients with haematological relapse, five received second transplants and two survive; 13 of the other 14 survive in chronic phase at median times from allografting and from recognition of haematological relapse of 41 months (range 25-59 months) and 18 months (range 5-36 months) respectively. For these 13 patients disease progression after relapse seems to be relatively indolent. In the four patients we could study, blood lymphocytes were almost all of donor origin. We suggest that even in patients with cytogenetic or haematological evidence of relapse after T-cell depleted BMT, leukaemic cell proliferation may still be restrained to some extent by a graft-versus-leukaemia effect mediated by donor-derived lymphoid cells.

Detection of residual bcr/abl translocation by polymerase chain reaction in chronic myeloid leukaemia patients after bone-marrow transplantation

The polymerase chain reaction was used to evaluate minimum residual disease in chronic myelogenous leukaemia (CML) patients after bone-marrow transplantation, by amplification of the transcript of the specific bcr/abl hybrid gene. Strict precautions were taken to avoid contamination. Peripheral blood cells from 22 patients transplanted for haematological malignant disorders were analysed. The results were clearcut for positive controls (patients with CML in relapse) and negative controls (patients with malignant disorders other than CML). In 11 of 12 CML patients in clinical and cytogenetic remission the bcr/abl transcript was detected 3 months to 6 years after transplantation. Thus, it appears that cells expressing the bcr/abl mRNA are not eradicated from the blood of CML patients in complete clinical remission even years after bone-marrow transplantation.

Cytogenetic follow-up after bone marrow transplantation for Philadelphia-positive chronic myeloid leukemia

Forty-eight consecutive patients affected by chronic myelogenous leukemia (CML) Philadelphia (Ph) chromosome positive during the chronic phase of the disease underwent allogeneic bone marrow transplantation (BMT). Thirty-five patients had a follow-up over 12 months and were included in a cytogenetic study in order to evaluate the Ph clone eradication. In 25 cases, the Ph chromosome disappeared in all cytogenetic studies, and their hematologic picture is at present apparently normal. Ten patients showed cytogenetic relapse. In one case, the cytogenetic relapse was transitory without any clinical sign of the disease; in three cases, after a transitory cytogenetic relapse, a persistent relapse with clinical picture of progression of the disease occurred; in six cases cytogenetic and a clinical relapse were coincident. Structural chromosomal abnormalities other than Ph were temporarily seen in three cases. The so-called "nonrandom" chromosomal changes typical of the blastic phase were never detected. The reappearing Ph-positive clone spontaneously disappeared in three patients, and their hematologic picture reverted to complete chimerism. The present study confirms that the eradication of the Ph clone is often defective with BMT, and cytogenetic analysis can detect the competition between donor and residual host marrow. Furthermore, the karyotype evolution is different from that found in CML patients treated with conventional chemotherapy.

Polymerase chain reaction for detection of residual leukaemia

The occasional finding of cells positive for the Philadelphia (Ph) chromosome months or years after bone-marrow transplantation for chronic myeloid leukaemia raises the possibility that the Ph-positive clone may never be eradicated. The polymerase chain reaction with probes able to detect the transcript of the bcr/abl hybrid gene at very low levels was used to study marrow cells from seven patients in continuing haematological and cytogenetic remission 5-7 years after allogeneic bone-marrow transplantation for chronic myeloid leukaemia. No evidence of the leukaemic mRNA was found. Thus, it seems that all leukaemic cells were eradicated in these patients and that they are truly cured.

Myelodysplastic relapse of de novo acute myeloid leukaemia with trilineage myelodysplasia: a previously unrecognized correlation

We describe the occurrence of an unusual mode of relapse in six of 24 patients who presented with de novo acute myeloid leukaemia (AML) associated with trilineage myelodysplasia (TMDS). After the induction of complete remission (CR) by intensive chemotherapy in five patients and following bone marrow transplantation (BMT) in one, the myelodysplastic state, but not overt AML, recurred. Relapse of myelodysplasia occurred at a median of 147 weeks (50-520) from presentation and in two instances was followed a year later by AML. In five cases, myelodysplastic relapse was treated with low-dose cytosine arabinoside given alone or with other chemotherapeutic agents. Three patients remain in CR after 1, 2 and 5 years. The reappearance of myelodysplastic features in these six patients was strongly correlated with the presence of TMDS at presentation of the AML. It was not observed once in the 136 AML patients, treated similarly, who did not have associated TMDS at presentation (P less than 0.001). Thus, relapse with myelodysplasia is not an effect of chemotherapy as has been previously postulated.

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.