Autotransplants in chronic myelogenous leukaemia: strategies and results

The role of hematopoietic stem cell transplantation in chronic myeloid leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) is currently recommended as 2nd or 3rd line therapy for patients with chronic myeloid leukemia (CML) in first chronic phase or as salvage for patients with very advanced disease. As a consequence, numbers of HSCT in chronic phase have dropped significantly since the introduction of tyrosine kinase inhibitors (TKI), numbers of transplants in advanced disease to a lesser extent. These current recommendations consider primarily disease risk, defined as failure of TKI therapy; they might need to be adapted. We propose a more balanced appraisal of HSCT for individual patients which should include disease risk, transplant risk, and macroeconomic aspects. HSCT should be integrated into the treatment algorithms from diagnosis and be considered very early at first TKI failure for patients with high disease but low transplant risk. For patients with very advanced disease and high transplant risk in contrast, HSCT might only be recommended in a restricted research setting.

Expression of BCR/ABL and BCL-2 in myeloid progenitors leads to myeloid leukemias

Chronic myelogenous leukemia is a myeloproliferative disorder (MPD) that, over time, progresses to acute leukemia. Both processes are closely associated with the t(9;22) chromosomal translocation that creates the BCR/ABL fusion gene in hematopoietic stem cells (HSCs) and their progeny. Chronic myelogenous leukemia is therefore classified as an HSC disorder in which a clone of multipotent HSCs is likely to be malignantly transformed, although direct evidence for malignant t(9;22)+ HSCs is lacking. To test whether HSC malignancy is required, we generated hMRP8p210BCR/ABL transgenic mice in which expression of BCR/ABL is absent in HSCs and targeted exclusively to myeloid progenitors and their myelomonocytic progeny. Four of 13 BCR/ABL transgenic founders developed a chronic MPD, but only one progressed to blast crisis. To address whether additional oncogenic events are required for progression to acute disease, we crossed hMRP8p210BCR/ABL mice to apoptosis-resistant hMRP8BCL-2 mice. Of 18 double-transgenic animals, 9 developed acute myeloid leukemias that were transplantable to wild-type recipients. Taken together, these data indicate that a MPD can arise in mice without expression of BCR/ABL in HSCs and that additional mutations inhibiting programmed cell death may be critical in the transition of this disease to blast-crisis leukemia.

Chronic myelogenous leukemia as a paradigm of early cancer and possible curative strategies

The chronological history of the important discoveries leading to our present understanding of the essential clinical, biological, biochemical, and molecular features of chronic myelogenous leukemia (CML) are first reviewed, focusing in particular on abnormalities that are responsible for the massive myeloid expansion. CML is an excellent target for the development of selective treatment because of its highly consistent genetic abnormality and qualitatively different fusion gene product, p210(bcr-abl). It is likely that the multiple signaling pathways dysregulated by p210(bcr-abl) are sufficient to explain all the initial manifestations of the chronic phase of the disease, although understanding of the circuitry is still very incomplete. Evidence is presented that the signaling pathways that are constitutively activated in CML stem cells and primitive progenitors cooperate with cytokines to increase the proportion of stem cells that are activated and thereby increase recruitment into the committed progenitor cell pool, and that this increased activation is probably the primary cause of the massive myeloid expansion in CML. The cooperative interactions between Bcr-Abl and cytokine-activated pathways interfere with the synergistic interactions between multiple cytokines that are normally required for the activation of stem cells, while at the same time causing numerous subtle biochemical and functional abnormalities in the later progenitors and precursor cells. The committed CML progenitors have discordant maturation and reduced proliferative capacity compared to normal committed progenitors, and like them, are destined to die after a limited number of divisions. Thus, the primary goal of any curative strategy must be to eliminate all Philadelphia positive (Ph+) primitive cells that are capable of symmetric division and thereby able to expand the Ph+ stem cell pool and recreate the disease. Several highly potent and moderately selective inhibitors of Bcr-Abl kinase have recently been discovered that are capable of killing the majority of actively proliferating early CML progenitors with minimal effects on normal progenitors. However, like their normal counterparts, most of the CML primitive stem cells are quiescent at any given time and are relatively invulnerable to the Bcr-Abl kinase inhibitors as well as other drugs. We propose that survival of dormant Ph+ stem cells may be the most important reason for the inability to cure the disease during initial treatment, while resistance to the inhibitors and other drugs becomes increasingly important later. An outline of a possible curative strategy is presented that attempts to take advantage of the subtle differences in the proliferative behavior of normal and Ph+ stem cells and the newly discovered selective inhibitors of Bcr-Abl. Leukemia (2003) 17, 1211-1262. doi:10.1038/sj.leu.2402912

Current Treatment of Chronic Myeloid Leukemia

We are entering an exciting era in the management of chronic myeloid leukemia (CML). This, in part is related to our considerable understanding of the molecular lesion associated with the disease-arguably the best characterized of any malignancy. Although allogeneic hematopoietic cell transplantation remains the sole potentially curative therapy at present, newer agents such as the tyrosine kinase inhibitor STI571 show promise and may eventually replace less specific cytotoxic therapy. This review focuses on the numerous options currently available for treating CML and includes a treatment algorithm.

Evaluation at single cell level of residual Philadelphia negative hemopoietic stem cells in chronic phase CML patients

In chronic myeloid leukemia, accurate determination of Ph(-) Hemopoietic stem cells (HSC) in peripheral blood (PB), bone marrow (BM) and leukapheresis products is important for the selection of patients for whom mobilization, collection, and autografting of Ph(-) HSC are envisaged. To this effect, the BCR/ABL fusion was assessed at the single cell level in 25 sets of PB and BM samples using dual-color I-FISH in immunophenotyped CD34(+) cells and RT-PCR of individual CFU-GM colonies. In 15 cases found to be 100% Ph(+), the respective BCR/ABL gene was absent in 30% of CD34(+) cells, while the respective transcripts could not be identified in 17% of CFU-GM. The mean percentage of BCR/ABL(-) CD34(+) cells and CFU-GM cells was higher (38% and 29%, respectively) in untreated patients than in treated patients (24% and 7%, respectively). In eight cases with cytogenetic response (CgR), the percentage of Ph(-) metaphases correlated with the level of BCR/ABL(-) colonies in BM and PB and with the proportion of BCR/ABL(-) CD34(+) cells in the BM. Immunophenotyping and FISH was fast, easy, always informative, and quantitative for the BCR/ABL(-) CD34(+) cells. Our results show that (a) at early diagnosis a high frequency of BCR/ABL(-) HSC circulate in the PB and that Ph(-) hematopoiesis is not completely suppressed; (b) although normal clonogenic cells decline rapidly within a few months after diagnosis, appreciable numbers of normal CD34(+) cells survive in chronic phase, especially in patients with CgR.

Effect of antisense oligonucleotides on CD34+ cells from chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a hematopoietic stem cell disorder characterized by a specific hybrid gene BCR-ABL (formed as a result of t(9;22)). This leads to two possible mRNA usually present in leukemic cells, either B2A2 or B3A2. Targeting these mRNA by antisense oligonucleotides (AS) might offer the opportunity to decrease leukemic growth. We have tested the ability of AS to inhibit the in vitro proliferation of CD34 positive (CD34+) blood cells from 16 patients with newly diagnosed CML. CD34+ cells were isolated by an immunomagnetic technique and incubated for 16 to 18 hours with an 18 mer AS (0.25 mM). Sense oligonucleotides served as controls. The effects of AS were evaluated by clonogenic test (production of CFU-GM). Moreover, colonies were picked out and studied by RT-PCR to analyse the presence of BCR-ABL transcript. For nine patients with B3A2 transcript, the median inhibition of CFU-GM formation at day 14 was 64.0 +/- 11.2% (68.0 +/- 11.4% at day 21) and for the seven patients with a B2A2 transcript: 59.0 +/- 11.4% (72.5 +/- 12.0% at day 21). AS showed no effect on CD34+ cells from three normal volunteer donor cells. However, for every patient studied, colonies picked out remained BCR-ABL positive with the RT-PCR technique.

Distinct effect of retroviral-mediated IFN-alpha gene transfer on human erythroleukemic and CD34+ cell growth and differentiation

Human interferon-alpha (IFN-alpha) has been used in the management of leukemia, but its diverse adverse effects may influence the ability of IFN-alpha to treat this disease. We constructed two retroviral vectors, LSN-IFN-alpha and LNC-IFN-alpha, in which IFN-alpha cDNA was driven by viral LTR and CMV promoters, respectively. After transduction into the PA317 and PG13 retroviral packaging cells, high titers of retrovirus were produced and were used to infect K562 and human BM CD34+ hematopoietic cells. The IFN-alpha gene expression in transduced K562 cells was confirmed by Northern blot, RT-PCR, RIA, and biologic assay. Cell proliferation and cell viability in IFN-alpha-transduced K562 cells were significantly suppressed as compared with control K562 cells. Although the IFN-alpha expression in K562 cells did not affect BCR/ABL expression, it apparently upregulated the production of adhesion molecules (VLA-4 and Mac-1). We evaluated the effect of IFN-alpha gene transfer on human CD34+ cells infected with LSN-IFN-alpha retrovirus with the aid of fibronectin (FN) fragment CH-296 and growth factors. RIA showed that IFN-alpha-transduced CD34+ cells produced 72.2+/-15 U/ml of IFN-alpha compared with 4.3+/-1.2 U/ml in control CD34+ cells. Methylcellulose clonogenic assay indicated that IFN-alpha-transduced CD34+ cells produced similar numbers of burst-forming units-erythrocytes (BFU-E)/colony-forming units-GM (CFU-GM) colonies as compared with control CD34+ cells. Selected colonies expressed IFN-alpha and neo(r) mRNA, as measured by RT-PCR. These studies indicate that retrovirus-mediated IFN-alpha gene transfer may provide a useful tool for studying the effect of IFN-alpha gene transfer on leukemic cells and long-lived CD34+ cells.

Long-Term Follow-Up of the Italian Trial of Interferon- Versus Conventional Chemotherapy in Chronic Myeloid Leukemia

Several prospective randomized studies have shown that the treatment of chronic myeloid leukemia with interferon- (IFN-) prolongs the survival by comparison with conventional chemotherapy. However, although IFN- can induce cytogenetic responses, true complete remissions are rarely achieved and information on the long-term effects of IFN- treatment is limited. For that purpose, we updated and analyzed a prospective comparative trial of IFN- and conventional chemotherapy that was initiated in 1986. The first analysis of the trial was already published, and showed a survival advantage for IFN- (N Engl J Med 12:820, 1994). The observation period of living patients now ranges between 95 and 129 months and we examined the long-term effects of IFN- treatment, always by comparison with conventional chemotherapy and according to the intention-to-treat principle. The patients who were submitted to allogeneic bone marrow transplantation (BMT) in chronic phase (38 of 322 or 12%) were censored at the date of BMT. Seventy-three of the original 284 nontransplanted patients were alive, 56 (30%) in the IFN- arm and 17 (18%) in the chemotherapy arm. Forty-one patients overall (14%) were still receiving IFN-. In the IFN- arm 9 patients were in continuous complete cytogenetic remission and 11 were in major or minor cytogenetic remission. Median and 10-year survival of low-risk patients were 104 months (95% CI, 85 to 127 months) and 47% (95% CI, 36% to 59%) in IFN- arm versus 64 months (95% CI, 49 to 98 months) and 30% (95% CI, 16% to 44%) in chemotherapy arm (P = .03). Median and ten-year survival of non–low-risk patients were 69 months (95% CI, 56 to 76 months) and 16% (95% CI, 8% to 24%) in IFN- arm versus 46 months (95% CI, 39 to 61 months) and 5% (95% CI, 0% to 11%) in chemotherapy arm (P = .006). A low Sokal’s risk, hematologic response, and cytogenetic response were associated with a longer survival. No major or unusual side effects were recorded after the 5th year of IFN- treatment. Fourteen patients died in chronic phase, 9 (4%) in IFN- arm and 5 (5%) in chemotherapy arm, mainly of cardiovascular accidents (6 cases) and of other cancers (5 cases). We conclude that a policy of chronic treatment with IFN- maintained a significant survival advantage over conventional chemotherapy on a long-term basis and irrespective of the risk. However, the great majority of the long-term survivors were in the low-risk group. The question of treatment discontinuation was not addressed in this study.

© 1998 by The American Society of Hematology.

Long-Term Follow-Up of the Italian Trial of Interferon- Versus Conventional Chemotherapy in Chronic Myeloid Leukemia

Several prospective randomized studies have shown that the treatment of chronic myeloid leukemia with interferon- (IFN-) prolongs the survival by comparison with conventional chemotherapy. However, although IFN- can induce cytogenetic responses, true complete remissions are rarely achieved and information on the long-term effects of IFN- treatment is limited. For that purpose, we updated and analyzed a prospective comparative trial of IFN- and conventional chemotherapy that was initiated in 1986. The first analysis of the trial was already published, and showed a survival advantage for IFN- (N Engl J Med 12:820, 1994). The observation period of living patients now ranges between 95 and 129 months and we examined the long-term effects of IFN- treatment, always by comparison with conventional chemotherapy and according to the intention-to-treat principle. The patients who were submitted to allogeneic bone marrow transplantation (BMT) in chronic phase (38 of 322 or 12%) were censored at the date of BMT. Seventy-three of the original 284 nontransplanted patients were alive, 56 (30%) in the IFN- arm and 17 (18%) in the chemotherapy arm. Forty-one patients overall (14%) were still receiving IFN-. In the IFN- arm 9 patients were in continuous complete cytogenetic remission and 11 were in major or minor cytogenetic remission. Median and 10-year survival of low-risk patients were 104 months (95% CI, 85 to 127 months) and 47% (95% CI, 36% to 59%) in IFN- arm versus 64 months (95% CI, 49 to 98 months) and 30% (95% CI, 16% to 44%) in chemotherapy arm (P = .03). Median and ten-year survival of non–low-risk patients were 69 months (95% CI, 56 to 76 months) and 16% (95% CI, 8% to 24%) in IFN- arm versus 46 months (95% CI, 39 to 61 months) and 5% (95% CI, 0% to 11%) in chemotherapy arm (P = .006). A low Sokal’s risk, hematologic response, and cytogenetic response were associated with a longer survival. No major or unusual side effects were recorded after the 5th year of IFN- treatment. Fourteen patients died in chronic phase, 9 (4%) in IFN- arm and 5 (5%) in chemotherapy arm, mainly of cardiovascular accidents (6 cases) and of other cancers (5 cases). We conclude that a policy of chronic treatment with IFN- maintained a significant survival advantage over conventional chemotherapy on a long-term basis and irrespective of the risk. However, the great majority of the long-term survivors were in the low-risk group. The question of treatment discontinuation was not addressed in this study.

© 1998 by The American Society of Hematology.

Autografting as first line treatment for chronic myeloid leukaemia

Interest in autografting for chronic myeloid leukaemia and its clinical relevance has revived in recent years. This followed observations that with various chemotherapeutic regimens it was possible to achieve, temporarily at least, peripheral blood and bone marrow that were Philadelphia negative. Bone marrow or peripheral blood progenitor cells could then be harvested and reinfused following a high dose procedure, hopefully eliminating any residual disease, and resulting in prolonged disease free survival. This ideal has not yet been successfully achieved with current strategies. Recent results indicate that eliminating residual disease with current chemotherapy is not normally achievable. The use of more sensitive technologies such as polymerase chain reaction has revealed persistent disease in most if not all apparently Philadelphia negative cases. This is confirmed by results where disease relapse occurs following transplant in these cases. Despite this, clinically relevant remissions are obtained and further trials are indicated. In this review present treatment is discussed and future strategies, using novel techniques as an adjunct to current treatment, are proposed that might improve on present results or even lead to the elusive goal of cure.

Myelodysplasia and the leukemias

The armistice after World War II marked the beginning of an era that was to last to the end of the present century. It was an era in which many changes in medicine and nursing combined to alter the entire philosophy of managing malignant disease. More specifically, the fluid-phase tumors, which comprise myelodysplasia and the leukemias, were singled out for special attention. First there was the ease with which blood and bone marrow could be sampled, making serial investigations simple and practical. Second, cytotoxic drugs became available ranging from nitrogen mustard through cytosine arabinoside, the anthracycline antibiotics, and the epi-podophyllotoxins. Although cytomorphology of the hematopoietic tissue had been exquisitely defined with the use of Romanowsky stains coupled with electron microscopy, the diagnosis of leukemia was, before 1945, a death sentence for want of effective therapy. This changed dramatically with the introduction of the folate antagonists, and progress was unremitting as the range of new products expanded. Suddenly responses could be obtained with single agents, and fairly rapidly combinations were developed for cumulative antitumor effect. Many agents had undesirable toxicity among different organs. Although slightly different for myeloblastic or lymphoblastic variants, this approach produced apparent disease eradication. The concept of complete remission, both clinical and hematologic, was born. Some of our early enthusiasm has had to be tempered with the somber appreciation that not all patients can improve and many others experience relapses. Where then do we stand? Leukemic cells themselves seldom kill. It is the relentless and uncontrolled expansion of a neoplastic clone that leads to bone marrow failure, albeit at different rates in the various subtypes. In the acute forms, the common presentation remains symptomatic anemia, neutropenic sepsis, and thrombocytopenic bleeding. Differentiation from marrow aplasia may not be possible at first on clinical grounds, although bone tenderness, gingival hypertrophy, and skin infiltration are among the general useful differential signs. Findings in the circulation and the marrow are of cardinal importance in diagnosis; they provide the basis for classification. Improved accuracy has followed the introduction of cytochemical stains, and a widening range of monoclonal antibodies, and greater recourse to karyotyping, have enhanced diagnostic acumen. Treatment decisions rest on many variables or prognostic factors that include age, performance status, comorbidity, and disease category, with an ever increasing regard for the part played by cellular and molecular genetics. Despite skillful utilization of this wealth of information for optimal management, outcome often leaves much to be desired. Myelodysplasia encompasses a number of different syndromes in which the refractory anemias are indolent, whereas those with excess blasts progress toward overt leukemia. Considerable judgment is necessary in selecting patients for whom supportive therapy alone is appropriate and recognizing others, up to one third of patients for whom use growth factors that include erythropoietin, granulocyte or granulocyte monocyte-colony stimulating factors, and thrombopoietin can be justified. The often unfavorable result has been a stimulus to current investigations that examine the value of intensive chemotherapy or the more innovative bone marrow transplantation and its peripheral blood equivalent. Autografting is a newer alternative that does not have proved potential. Acute leukemia, whether myeloblastic or lymphoblastic, has been managed with mixed success. Remission rates have steadily increased and, notably among children, moved toward 100% in certain groupings. The downside of nonspecific drug regimens is that some patients simply may not respond, whereas others experience remissions and then relapses. (ABSTRACT TRUNCATED)

Multi-unit anti-BCR-ABL ribozyme therapy in chronic myelogenous leukemia

In this review, we summarize and update our data on the development of a multi-unit anti-BCR/ABL ribozyme. In vitro studies comparing several anti-BCR/ABL ribozymes demonstrated that a triple-unit ribozyme is the most efficient. Detailed kinetic analysis revealed this ribozyme to have a lower Kcat, most likely due to non homologous bases at restriction enzyme sites used in ribozyme construction. Delivery of this ribozyme to a BCR/ABL transformed cell line by a novel vehicle targeting the folate receptor resulted in a 3 log reduction in BCR/ABL mRNA when analyzed by RT-PCR. This delivery strategy reversed the IL-3 independence of this cell line. Retroviral vectors containing genes coding for the multi-unit ribozyme have been constructed and their use to effect BCR/ABL transformed cell biology is discussed.

Rationalizing autotransplant strategies for chronic myeloid leukemia

The molecular genetic basis of chronic myeloid leukemia (CML) is well-defined, but until recently therapeutic approaches have been largely empiric. Conventional chemotherapy and interferon offer palliation, but only bone marrow transplantation provides for cure. Because the majority of CML patients are not candidates for allogeneic transplantation, autologous strategies have emerged as an alternative. Data from murine models of CML provide insights into the mechanisms by which autotransplant might be effective in the treatment of CML. Further dissection of the molecular pathways by which the BCR/ABL protein can induce leukemia offers the promise of a more targeted, rationally-designed therapy. When used for remission maintenance therapy following autologous bone marrow transplantation, specific inhibitors of BCR/ABL should provide for long term disease-free survival.

Cytokines and bone marrow transplantation

This article summarizes the various current uses of cytokines, and bone marrow and peripheral blood stem cell transplantation for cancer treatment. Interferons, interleukin-2 and hematopoietic growth factors are extensively used for the treatment of hematopoietic as well as nonhematopoietic malignancies, either as the main therapeutic agents or as an adjuvant. Research on gene therapy using cytokines is in progress. Stem cell transplantation is also discussed in the context of gene therapy of cancer. Gene therapy is expected to become a future modality in cancer treatment.

The role of natural killer cells in the treatment of chronic myeloid leukemia

The success of chemotherapy in patients with leukemia whose marrow appears to be replaced by leukemia cells must be due to the persistence of normal stem cells. In this normal population are the progenitors of the cells of the immune system. Natural killer (NK) cells originate in the bone marrow. On maturation and activation with interleukin 2 (IL-2) or other cytokines, NK cells develop cytotoxic activity against a variety of leukemic blasts, including those from patients with chronic myeloid leukemia (CML). In the past few years, bone marrow transplantation (BMT) and alpha-interferon (IFN-alpha) have proved to be the most promising therapies for the treatment of CML. In both these therapies, NK cells may play a prominent role. In this article, we discuss the antitumor/antileukemia activity of human NK cells, the presence of benign NK cell precursors in the different stages of CML, the role of NK cells in BMT and IFN-alpha treatment, and the potential therapeutic applications of NK cells in patients with hematologic malignancies.

Recovery of T-lymphocytes for adoptive immunotherapy by lymphapheresis of HIV-infected patients without alterations of virological, immunological or clinical parameters

We performed repeated continuous flow cytaphereses (CFC) on 13 asymptomatic HIV-1-infected patients to study the feasibility of cell separation procedures to recover high yields of peripheral blood T-lymphocytes for adoptive immunotherapy in HIV-infected patients and to determine immunological and virological alterations following such procedures. A mean yield of 6.23 x 10(9) lymphocytes could be obtained by each cytapheresis, containing 1.82 x 10(9) CD4+, 3.23 x 10(9) CD8+ T-lymphocytes and 8.39 x 10(6) CD34+ peripheral progenitor cells. The CD4/CD8 ratio (mean 0.53, SD +/- 0.15) in the cell samples reflected the distribution of the lymphocyte subsets in vivo. Absolute lymphocyte counts decreased at a mean of 404/mm3 (25%) immediately after CFC but were replaced from the extravascular pool within 1 h. The CD4/CD8 ratios, p24-antigenaemia, HLA-DR expression and neopterin levels did not change significantly after cell separation. No alteration of the number of T-cells with integrated proviral DNA copies (1/10(3) to 1/10(6)) could be detected in peripheral T-helper cells by PCR after lymphapheresis. We conclude that high yields of peripheral T-lymphocytes can be obtained by continuous flow lymphapheresis for cell-mediated immunotherapy, without deterioration of virological or immunological parameters in HIV-infected patients. The separated T-cells are fully replaced from extravascular pools after 1 h.

High-dose cyclophosphamide for mobilization of circulating stem cells in chronic myeloid leukemia

Experimental and clinical data suggest that Ph-negative myeloid progenitor cells are present, albeit suppressed, in the bone marrow of chronic myeloid leukemia (CML) patients. These residual Ph-negative cells might, in certain circumstances, regain their proliferative advantage over the leukemic Ph-positive clone. Treating CML patients with intensive chemotherapy might allow the harvest, in the early phase of recovery, of Ph-negative stem cells to be used as graft after myeloablative regimen. In our study, 6 CML patients were admitted to a program of autograft with circulating stem cells (CSC) collected after high-dose (5 or 7 g/m2) cyclophosphamide (HD-CY) mobilization. All were autografted, using busulphan 16 mg/kg and melphalan 60 mg/m2. As graft, 4 patients received CSC only, while 2 patients were also given bone marrow, as their peripheral blood CFU-GM yield was unsatisfactory. Two previously alpha-IFN-responding patients showed a slow hematologic recovery, but achieved a marked and further reduction of their Ph-positive metaphases post-graft. Moreover, in one of them, cytogenetic analyses performed on apheresis product showed a more pronounced reduction of his Ph-positive metaphases, as compared to bone marrow samples, suggesting a potential purging effect of the mobilization procedure.

Retroviral mediated gene transfer in chronic myelogenous leukaemia

Gene therapy for chronic myelogenous leukaemia (CML) may provide a therapeutic option for patients who are ineligible for bone marrow transplantation. To determine the feasibility of such an approach we evaluated the transduction efficiency of CML progenitor colonies from seven patients in chronic phase. Vector transduction was optimized using the CML-derived K562 cell line and applied to CML mononuclear cells. After vector exposure, optimal gene transfer was noted when CML mononuclear cell cultures contained stem cell factor, IL-3, GM-CSF and erythropoietin. The addition of IL-6 to this combination decreased transduction efficiency. Using these conditions, 20.4% +/- 2.4 (SE) of erythroid colonies (CFU-GEMM and BFU-E) and 20.2% +/- 4.7 of CFU-GM colonies were G418 resistant. This compares with a transduction efficiency of 5.9% +/- 1.1 and 6.4% +/- 1.5, respectively, for erythroid and CFU-GM colonies using marrow obtained from normal donors. Only a modest increase in gene transfer was noted when CML cells were stimulated with cytokines for the 24 h preceding vector exposure. Vector DNA in colonies expressing the BCR/ABL transcript was documented by performing PCR analysis on individual colonies. The relatively high gene transfer rate in CML suggests that this disease might be very suitable for gene therapy.

Long-term survivors in chronic granulocytic leukaemia: a study by the International CGL Prognosis Study Group. Italian Cooperative CML Study Group

The purpose of the present work were to identify the initial characteristics associated with long-term survival in chronic granulocytic leukaemia (CGL) and to analyse the accuracy of prognostic models in identifying long-term survivors. 813 Philadelphia (Ph) chromosome-positive, nonblastic CGL patients from six American and European institutions, the majority treated conventionally, with a minimum follow-up > 10 years, were studied. Stepwise logistic regression was performed to ascertain the association between the initial clinicohaematological variables and survival > or = 8 years, and a prognostic index was derived. The usefulness of both Sokal's and the new prognostic index to identify long-term survivors was assessed by calculating their positive and negative predictive accuracies, sensitivity and specificity. Median survival of the series was 45 months (range 1-255), with 784 patients (96.4%) having died and 109 (13.4%) surviving 8 years or longer. Younger age, smaller spleen, platelets < or = 600 x 10(9)/l, and lower blood blast percentage were associated with survival > or = 8 years; platelets < or = 600 x 10(9)/l and lower blood blast percentage were the predictive factors in patients 50 years old or younger. Two-thirds of long survivors belonged to Sokal's low-risk group, but the positive predictive accuracy and specificity for prolonged survival of Sokal's index were very low. This was also the case for the new predictive index.(ABSTRACT TRUNCATED AT 250 WORDS)

Autologous peripheral stem cell transplantation of the blastic phase of chronic myeloid leukemia following sequential high-dose cytosine arabinoside and melphalan

Blast-phase chronic myelogenous leukemia (CML) is the terminal phase in CML and is uniformly fatal. We treated 12 patients with blast-phase CML with a program of high-dose cytarabine 3.0 g/m2 and melphalan 140 mg/m2, followed by reinfusion of stem cells obtained from peripheral blood during the chronic phase. Seven patients achieved either a partial or complete hematologic remission, while five patients showed no response to therapy. One patient returned to chronic phase features with loss of a chromosomal abnormality acquired at blast phase, restoration of hematopoiesis, and a decrease in the amount of bone marrow blasts to less than 10%. Six patients cleared their peripheral blasts and showed recovery of their myeloid and platelet lineages, but all six required treatment for acceleration within 3 months. Of the five nonresponding patients, three died with aplastic bone marrow, one patient never cleared peripheral blasts after chemotherapy, and one patient had evidence of peripheral blasts 3 weeks after the autologous stem cell reinfusion. None of the patients returned to a normal karyotype. The ablative regimen was effective in eradicating bone marrow blasts to < 10% in 8 of 10 patients in whom interpretable bone marrow samples were performed following chemotherapy. Overall, the median survival for all patients from the time of stem cell reinfusion was 5.5 months. We conclude that autotransplants with peripheral blood can successfully be used to support hematopoiesis during high-dose therapy for CML blast crisis, however, has no role by itself in the curative therapy of blast crisis CML. A small number of patients can be restored to chronic phase features, and this may provide an opportunity to administer subsequent alternative treatments designed to eradicate the malignant stem cell population. Autotransplants with stem cells may also be used as therapy for patients without a histocompatible marrow donor. However, the autotransplant may be more effective when used during the chronic phase of CML, with the use of hematopoietic growth factors, and with reinfusion of stem cells depleted of the malignant Philadelphia chromosome-positive clone.

Persistence of bcr-abl mRNA-expressing cells in long-term cultures established from chronic myeloid leukemic bone marrow or blood

Long-term cultures (LTC) established from chronic myeloid leukemic (CML) bone marrow or blood contain bcr-abl mRNA-expressing cells, as demonstrated by the polymerase chain reaction (PCR). Bcr-abl sequences were detectable in cultures from all of nine patients investigated. In LTC from two patients, in which a cytogenetic conversion from Ph+ to Ph- was noted at day 20 and 40, respectively, the PCR for bcr-abl remained positive, at least up to day 112 and 245, respectively, in vitro. The differences between the results of cytogenetic and PCR analyses was explained by the fact that the metaphases studied were obviously derived from spontaneously EBV-transformed bcr-abl mRNA-negative B cells, which may become the dominating cell type very early in LTC from bone marrow or blood. LTCs cloned for EBV-transformed B cells which no longer harbor admixed macrophages are bcr-abl mRNA negative. In conclusion, bcr-abl mRNA-expressing cells may show long-term persistence in LTC established from CML bone marrow or blood.

Bone marrow transplantation in leukemia

Bone marrow transplants are increasingly being used as treatment for leukemia. Several IBMTR studies have identified variables predicting outcome in allogeneic transplants. These studies have also identified factors like GVL that increase our understanding of leukemia treatment. Following the success of HLA-identical sibling transplants, allografts from related and unrelated donors are now performed frequently and achieve long-term LFS. The use of autologous transplants, with and without marrow treatment, is also increasing and continues to be investigated as an alternative therapy for leukemia.

What really cures in autologous bone marrow transplantation? A possible role for dimethylsulfoxide

Dimethylsulfoxide has long been known to be a potent inducer of differentiation of various malignant cells in animals and human beings. It is a toxic agent, and high concentrations are needed to induce differentiation. Other compounds that also have methylene groups and a polar/apolar architecture, and are needed in much smaller concentrations to induce differentiation, like hexamethylene bisacetamide have been developed. They are already used in trials in human beings. However dimethylsulfoxide still has a very important role in bone marrow transplantation, being added to the frozen marrow as a cryoprotectant. We suggest that dimethylsulfoxide may induce differentiation of malignant cells present in the marrow or alternatively in the body when it is infused back with the transplanted marrow. This may be an additional factor contributing to the success rate achieved in various malignancies treated by transplantation, especially autologous, complementing the traditional explanations which are based mainly on the high dose chemotherapy and the immunological manipulations that occur during transplantation.

Synergistic cytotoxicity of AZT plus alpha and gamma interferon in chronic myeloid leukemia cell line K562

We have previously reported that the antineoplastic activity of 3'-azido 3' deoxythymidine (AZT) can be increased by drugs that inhibit "de novo" thymidylate synthesis, such as 5-fluorouracil, methotrexate and hydroxyurea. In the present study we tested the combinations AZT+alpha interferon (IFN) and AZT+gamma IFN on in vitro growth of the human acute-phase chronic myeloid leukemia (CML) cell line K562. After 72 hours incubation, not only AZT+alpha-IFN but also AZT+gamma-IFN were synergistic in inhibiting K562 growth, as demonstrated by isobologram analysis of the data. This enhanced cytotoxicity was confirmed by the evaluation of [3H]AZT incorporation into cellular DNA, that was increased by 50% and 222% in the presence of alpha- and gamma-IFN, respectively. The addition of 50 mumol/l thymidine to the culture medium was able to reduce the cytotoxicity of the drug combinations to the degree observed with each compound alone; furthermore, the increased incorporation of AZT into DNA was completely reversed. These data indicate the existence of a biochemical interaction between AZT and IFNs that results in an increased cytotoxic effect. While the combination AZT+alpha-IFN is currently being tested in HIV-related malignancies, AZT+gamma-IFN is new and deserves further study in human CML acute and chronic phase models, in view of possible clinical applications.

Residual Ph-negative stem cells in chronic myeloid leukemia--sometimes or always?

Some patients with Philadelphia (Ph) chromosome-positive chronic myeloid leukemia (CML) may achieve partially or completely Ph-negative hemopoiesis after treatment with high doses of cytotoxic drugs or interferon-alpha at standard dosage. This observation leads to three important questions: 1) are Ph-negative myeloid cells in such patients strictly normal? 2) can such Ph-negative cells be identified in all newly diagnosed patients or only in a minority? and 3) what is the basis for the proliferative advantage manifested by CML cells and why might it be temporarily lost as a result of treatment? The mechanisms that might prevent the proliferation of normal cells in an environment of Ph-positive cells and the relevance of these questions to the design of a strategy aimed at obtaining complete remission in the majority of patients are considered. Such a strategy might incorporate autografting with Ph-negative stem cells harvested during the recovery phase of high dose chemotherapy.

Autografting in chronic myelogenous leukemia followed by immunotherapy

Patients with chronic myelogenous leukemia (CML) can be cured with allogeneic bone marrow transplantation. Over the past decade, it has become clear that immunological mechanisms, in the form of graft-versus-leukemia, constitute an integral part of this therapy. Because of limitations imposed by a lack of suitable donors, age, and toxicity, only a minority of patients can be offered allogeneic bone marrow transplantation (BMT). Recently, attempts have been made to employ autologous bone marrow transplantation (ABMT) for the therapy of CML using a variety of pre- and post-transplantation manipulations. This report describes the rationale for an ongoing clinical trial using the immunomodulator roquinimex (Linomide), following autologous bone marrow transplantation, in an attempt to stimulate the immunological responses thought to be critical for successful therapy in CML.

Hematologic remission and cytogenetic improvement after treatment of stable-phase chronic myelogenous leukemia with continuous infusion of low-dose cytarabine

Prolonged exposure to low concentrations of cytarabine preferentially inhibits in vitro growth of neoplastic myeloid progenitors from patients with chronic myelogenous leukemia (CML) compared to that of normal myeloid progenitors. Continuous infusions of cytarabine in doses of 15-30 mg/m2/day were therefore administered for extended periods to patients with CML in stable phase to determine if this treatment could achieve selective cytoreduction of Philadelphia chromosome (Ph)-positive cells. Five patients demonstrating > 90% Ph-positive metaphases before treatment received a total of 43 cycles of cytarabine infusional therapy. Cytarabine was administered on an outpatient basis using a portable, battery-operated syringe pump until the total leukocyte count reached 2500/microliters or the platelet count reached 75,000/microliters. A new cycle was begun when the total leukocyte count exceeded 4,000/microliters and the platelet count exceeded 100,000/microliters. The median duration of cytarabine administration per cycle was 29 days (range 15-72 days). Leukocytosis was readily controlled by low-dose cytarabine therapy in all patients. All five patients experienced complete hematologic responses during cytarabine therapy. The fraction of Ph-positive metaphases in the marrow of the five patients was reduced to 0, 10%, 43%, 72%, and 84%, respectively, during therapy. The median time to achieve optimal cytogenetic response was 4.8 months (range 2.8-8.6 months). One patient demonstrated a complete cytogenetic response after three cycles of cytarabine. Another patient demonstrated persistent cytogenetic improvement during 20 cycles of cytarabine, with a median 38% Ph-positive marrow metaphases (range 10-53%) over 32 months. Cytarabine therapy was generally well-tolerated, but was discontinued in one patient because of persistent asymptomatic elevations in hepatic enzymes, which resolved within 2 months after discontinuing therapy. There were no episodes of fever during neutropenia, and platelet transfusions were not required. However, symptomatic anemia requiring transfusion of red cells occurred during most cycles of treatment. In summary, treatment of CML with low-dose cytarabine can induce prolonged cytogenetic improvement in some patients with acceptable toxicity. Further evaluation is needed to ascertain the effect of this treatment on duration of stable phase and overall survival.

High dose hydroxyurea in collection of Philadelphia chromosome-negative stem cells in chronic myeloid leukaemia

High dose hydroxyurea (HU) was used in a pilot study to assess its efficacy in mobilizing Philadelphia (Ph) chromosome negative progenitor cells in chronic myeloid leukaemia (CML). Five patients received 12 g/M2 oral HU in divided doses. Side effects were minimal, allowing outpatient administration. Nine to fourteen days later 4 patients achieved a mean leukocyte nadir of 3.5 x 10(9)/L (Range 2.4-4.9) and a mean platelet nadir of 99 x 10(9)/L (Range 95-108). Peripheral blood mononuclear cells (PB-MNC) sampled prior to the HU priming were 100% Ph positive. Between 10 and 18 days post HU, 3 patients achieved a marked reduction (80-100%) in the number of Ph positive metaphases in PB-MNC collected by apheresis. One patient failed to achieve any Ph suppression. Polymerase chain reaction analysis (PCR) for the bcr-abl fusion product remained positive in all samples. Rapid rises in CFU-GM numbers were associated with a return to 100% Ph positive metaphases however slower rises represented recovery with predominantly Ph negative cells, allowing apheresis collection of these cells. We conclude that HU induces a reproducible leukocyte nadir with sufficient stem cell mobilization for potential autologous transplantation. Higher doses of HU together with early and intensive apheresis is required to maximize Ph negative progenitor cell harvests.

Photodynamic elimination of clonogenic Ph+ chronic myeloid leukemia cells

Benzoporphyrin derivative (BPD) and light is a potent photosensitizer. We investigated this modality as a means to selectively eliminate clonogenic Ph(+) chronic myeloid leukemia (CML) cells. BPD at 10 ng/ml and 10.8 J/cm2 broad spectrum light eliminates from 5 to 6 logs of Ph(+) EM-2 cells. Long-term marrow culture studies of treated mixtures of normal and CML cells indicate that multipotent progenitor cell viability is retained while cells transcribing BCR-ABL are not detected. We conclude that BPD and light may offer a means of providing CML autografts potentially free of Ph(+) clonogenic cells.

Clinical models of autotransplants in chronic myelogenous leukemia

We analysed relapse risk after syngeneic and allogeneic T cell depleted transplants to predict the outcome after autotransplants in chronic myelogenous leukemia (CML). These data suggest that high dose pre-transplant conditioning may cure about 50% of the persons in chronic phase and about 10% of those in more advanced phases. The expected relapse rate would be about 50-90%. However, additional relapses might occur from infusing leukemia cells with the graft. Different approaches are being attempted to eliminate leukemia cells from the graft. It is however unlikely that their effect could be demonstrated in clinical trials. Recent analyses in persons relapsing after allogeneic T depleted transplants suggest that reducing the CML cell mass by high dose chemotherapy may prolong duration of survival.

Management of chronic myeloid leukemia in chronic phase with autologous stem cell transplantation and alpha-2 interferon: cytogenetic and clinical results

Forty-eight patients with chronic myeloid leukemia (CML) in chronic phase (CP) were treated by autologous stem cells transplantation (ASCT) and alpha Interferon (IFN) with three approaches: 1) ASCT at diagnosis followed by IFN, 2) ASCT post IFN with cells collected after an interval from IFN discontinuance, followed by IFN, 3) ASCT in patients selected by cytoconversion obtained with IFN, performed soon after IFN discontinuance. Following ASCT, a major karyotype response (more than 65% Ph1 negative cells, MKR) was observed at least once in 40%, 53% and 83% of patients from the three groups, respectively. At last follow-ups (median 39, 40 and 21 months, respectively) 19%, 13% and 67% of patients still present a MKR with 2 patients from group 1 and 4 patients from group 3 being 100% Ph' negative. Projected survival from diagnosis is 77% at 52 months for patients from group 1 and 47% at 75 months for patients from group 2. Present data indicate that 1) IFN can stabilize results obtained with ASCT, 2) ASCT can potentiate responses to IFN, 3) combined ASCT and IFN can improve survival. Longer follow-up of patients and randomized studies are required to define the real impact on disease outcome by these treatment approaches.

Chronic myeloid leukaemia treated by allogeneic bone marrow transplantation from histocompatible sibling donors--an invariably fatal malignancy rendered highly curable

Twenty-eight patients aged 16-50 years with chronic myeloid leukaemia (CML) underwent allogeneic bone marrow transplantation (BMT) using human leukocyte antigen (HLA)-identical sibling donors. Of the 28 patients, 21 were in chronic phase, five were in accelerated phase and two were in blast phase at the time of BMT. Twenty-three of the patients survived more than 63-2187 days after BMT, 21 in continuous complete remission and two with haematologic relapse of CML. Two patients died of interstitial pneumonitis and one died of relapsed CML, cerebral aspergillosis and cytomegalovirus enterocolitis. The overall probability of survival at six years was 78% +/- 9% (mean +/- standard error) and of disease free survival 66 +/- 11%. For patients transplanted in chronic phase, the survival probability was 90 +/- 6%, while all of the patients undergoing BMT in chronic phase within the first year after diagnosis were alive with a relapse-free survival of 88 +/- 12%. The actuarial probability of occurrence of acute graft-versus-host disease (GVHD) was 57 +/- 9%, while for Grades II and III GVHD it was 28 +/- 9%. Chronic GVHD occurred in 18 of 25 patients at risk. The majority of patients had a Karnofsky performance score at latest follow-up of at least 90% (range 50-100). We conclude that allogeneic BMT is effective, curative therapy for CML and that BMT performed earlier in the natural history of the disease is associated with the best outcome.

The scientific bases of cancer management: at the interface between fundamental research and clinical practice

From 1950 to 1985 the 5-year survival rate of cancer patients in industrialized countries, has slowly increased from 25% in 1950 to 50% in 1985. This progress has been due to earlier diagnosis and to a gradual improvement of treatment modalities. Clinical needs have stimulated basic research and clinical investigation. In turn, biological research has introduced new concepts and new agents. Clinical investigation and applied research have brought about an improvement in therapeutic methods and a better understanding of the growth and progression of human cancers which has, in particular, led to the concept of adjuvant treatment of occult metastases. The major recent breakthroughs in fundamental research have reinforced the value of close cooperation between clinicians and fundamentalists. Most of the new biologic tools are specific and only active on tumors cells with well-defined characteristics. Furthermore some new techniques such as adoptive immunotherapy can induce complete tumor regression in some patients and have no detectable effects in other patients with apparently similar tumors. Some cytokines have different effects on experimental and human tumors. The cytokine network is so complex that the administration of one of them can induce unpredictable effects. It has been recognized that experimental tumors and in vitro studies can be misleading and there is no substitute for clinical studies on patients. Moreover clinical experience has documented the amazing ability of tumors to become resistant to all these new agents. Numerous new therapeutic methods are being explored, however with the current state of knowledge it appears that although they can help to control tumors, they still fail to eradicate them. We must therefore learn how to integrate them with conventional therapies. Advances in therapy shall be achieved only by well-designed clinical trials. Thus at the interface between fundamental research and clinical practice there is an urgent need for oncologists with a strong scientific background and laboratory scientists with a deep interest in clinical investigations.

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?