Intensive combination chemotherapy and autologous bone marrow transplantation leads to the reappearance of Philadelphia chromosome-negative cells in chronic myelogenous leukemia

Autologous stem cell transplantation for patients with chronic myeloid leukemia. The Argentine Group of Bone Marrow Transplantation (GATMO) experience

BACKGROUND

The objective of this analysis was to evaluate the role of autologous stem cell transplantation (ASCT) in prolonging disease free survival (DFS) and overall survival (OS) in patients with chronic myeloid leukemia (CML) who received autografts of Philadelphia chromosome (Ph) positive or Ph negative cell harvests.

METHODS

Over a 4-year period (1994-1999), 53 patients who underwent ASCT for CML were reported to the Argentine Group of Bone Marrow Transplantation (GATMO) Registry.

RESULTS

Ph negative cell products were harvested in only 18 patients (34%). Comparison of disease status at the time of autograft, duration of neutropenia, thrombocytopenia, days of antibiotics, and transfusional requirements of red blood cells and platelets did not reveal statistical significant differences between the Ph positive group and the Ph negative group. Only days of hospitalization were increased significantly in patients who received Ph positive autografts. Although DFS at 36 months was significantly longer after infusion of Ph negative cell products (54% vs. 14%; P <or= 0.005), OS differences between the Ph negative group and the Ph positive group (68% vs. 53%; P <or= 0.134) were not significant.

CONCLUSIONS

ASCT with Ph negative cell harvests after myeloablative chemotherapy resulted in prolonged periods of hematologic and cytogenetic remission or stable disease after cytogenetic/molecular recurrence in some patients with CML. A superior DFS was observed without any benefit observed for OS.

Second chronic phase before transplantation is crucial for improving survival of blastic phase chronic myeloid leukaemia

Because successful outcome after transplantation seems to depend in acute myeloid leukaemia (AML) and in chronic phase chronic myeloid leukaemia (CML) on disease status at the time of transplantation, we investigated whether FLAN (fludarabine, cytosine arabinoside, mitoxantrone) induction before allogeneic stem cell transplantation (allo-SCT) may be useful in blastic phase (BP)-CML. Twenty patients with BP-CML were studied: 10 patients received FLAN induction chemotherapy before proceeding to early allo-SCT, whereas 10 patients were submitted to bone marrow transplantation (BMT) without remission induction. Eight out of 10 (80%) patients achieved second chronic phase after one course of therapy with FLAN and seven patients (six in second chronic phase and one with partial response) were then submitted to allo-SCT. Of the six patients transplanted in the second chronic phase, all achieved molecular remission, four are still in second chronic phase, with intervals ranging from 10 to 54 months, whereas one patient died from infection having relapsed 14 months after SCT and one died of transplant-related complications in the second chronic phase. Mean durations of second chronic phase and survival after allo-SCT were both significantly longer than in the group of 10 BP-CML patients submitted to allo-SCT without FLAN remission induction treatment [22.4 (range 1-61) vs. 3.5 months (range 1-10) with FLAN and 22.7 (range 2-61) vs. 6.4 (range 1-16) months without FLAN]. We conclude that FLAN induction therapy followed by early allo-SCT appears to be effective in the treatment of BP-CML and could provide a curative possibility for BP-CML patients.

Safe mobilization of normal progenitors in advanced chronic myeloid leukemia with intensive chemotherapy and granulocyte-colony stimulating factor

Twenty-one patients with advanced chronic myeloid leukemia (late chronic phase (n = 8), accelerated phase (n = 11) and blast crisis (n = 2)) were treated with idarubicin, cytarabine, and etoposide followed by G-CSF and subsequent collection of peripheral blood progenitor cells in the early recovery phase. Treatment was reasonably well tolerated with no deaths or intensive care admissions. Despite the advanced phase of disease and heavy pretreatment with cytotoxics and interferon-alfa, 11 of 21 patients (52%) achieved a cytogenetic response. Of the nine major cytogenetic responses (complete (n = 3) and partial (n = 6)), seven achieved adequate progenitor collections for consideration for autologous transplantation. The only predictor of response was disease duration (P = 0.02). With a median follow-up of 1171 days from treatment it appears unlikely that G-CSF contributed to disease progression. Survival post-IcE was predicted by disease stage (P = 0.0001). Intensive chemotherapy followed by G-CSF allowed adequate yields of predominantly Philadelphia chromosome negative progenitor cells to be obtained from one-third of patients with advanced CML.

Clinical course and therapy of chronic myelogenous leukemia with interferon-alpha and chemotherapy

This article begins with a review of the natural history of chronic myelogenous leukemia (CML), with an emphasis on prognostic features. Current standard therapy of CML with interferon-alpha based regimens, and interferon-alpha, in the context of allogenic stem cell transplantation is then discussed. Finally, some potentially effective novel agents including homoharringtonine, decitabine, ATRA, and topotecan are described.

Chronic myelogenous leukemia: a review

Chronic myelogenous leukemia (CML) is a chronic myeloproliferative disorder with an initially chronic course lasting for 3-5 years. It eventually transforms into accelerated and blastic phases, which are generally fatal. CML was one of the first diseases in which a specific chromosomal abnormality was identified, a t(9;22)(q34;q11) or Philadelphia chromosome. CML had been traditionally treated with conventional chemotherapy with hydroxyurea or busulfan. Although these agents can achieve hematologic remissions in most patients, no evidence of sustained disappearance of the chromosomal abnormality was evident. Interferon alpha (IFN-alpha) has been able to achieve hematologic and cytogenic remissions in a significant number of patients, and recent studies show a survival advantage for patients treated with IFN-alpha compared with those treated with conventional chemotherapy. The results of these studies are discussed, and the reasons for discordance among different investigators analyzed in this review. Allogeneic bone marrow transplantation (BMT) may be curative in some patients with CML. The benefits and limitations of this approach in the treatment of CML are also discussed and the results of different alternatives compared. Other alternatives of therapy, including newer chemotherapeutic agents, combinations of IFN-alpha with other agents, and autologous BMT, are presented. The availability of very sensitive techniques for detection of the Philadelphia chromosome at the molecular level has allowed the detection of minimal residual disease. The information available on these measurements is also analyzed. Finally, we discuss the alternatives for patients with accelerated and blastic phase CML, as well as the clinical characteristics and prognosis for patients with Philadelphia-chromosome-negative CML.

Interferon-alpha therapy for chronic myelogenous leukemia

PURPOSE

To provide a status report on the use of interferon (IFN)-alpha in patients with chronic myelogenous leukemia (CML).

DATA SOURCES

Data on IFN-alpha therapy for CML collected from published articles identified in a MEDLINE computer search.

RESULTS

Previously untreated patients with low-risk factors and early-stage disease consistently had the best results in clinical trials. A dose response was seen, with patients treated with dosages of 5 million units (MU)/m2 per day showing the greatest incidence of cytogenetic remissions. In addition, randomized trials showed a survival advantage for IFN-alpha-treated patients. In studies comparing IFN-alpha therapy to chemotherapy, IFN-alpha produced significantly more major and durable cytogenetic responses than chemotherapy did. In studies combining IFN-alpha and chemotherapy, patients had significantly more cytogenetic responses, although more patient accrual and follow-up data are needed to offer conclusive statements concerning durability of response. IFN-alpha also showed activity in maintaining remissions after both chemotherapy and bone marrow transplantation.

CONCLUSIONS

IFN-alpha has significant activity in patients with CML, with best results at dosages of 5 MU/m2 per day. At these dosages, in patients with early-stage, Philadelphia+ CML, hematologic response rates of 70% to 80% and cytogenetic response rates of 50% (approximately 20% of which were complete) are seen. One randomized trial shows a survival advantage with cytogenetic response in IFN-alpha-treated patients, and this advantage appears to be unrelated to the degree of that response. These questions remain under study.

Benign hematopoietic progenitors in chronic myeloid leukemia: current status and future prospects

Many patients with chronic myeloid leukemia (CML) retain a certain degree of normal hematopoiesis at disease presentation. This fact, suspected on the basis of cytogenetic findings, has been confirmed by long-term bone marrow cultures (LTBMC) and the combined use of phenotypic and molecular studies. Based on the lack of HLA-DR expression, it has been possible to recognize a benign subpopulation within the stem-cell compartment in CML. Different in vitro techniques have been developed for the selection of these benign progenitors, including LTBMC, marrow incubation with cytolytic drugs or interferon, positive selection based on their phenotypic characteristics, and exposure to synthetic antisense oligodeoxynucleotides. In vivo selection with interferon or intensive chemotherapy is also possible. The primary goal of the selection of benign hematopoietic progenitors is their use for autotransplantation. To date, a few hundred CML patients have been submitted to the latter procedure using bone marrow or peripheral blood. The fact that the majority of them show evidence of persistent disease emphasizes the necessity for better selection methods of the benign progenitors, for intensifying the conditioning regimen to reduce the tumor burden as much as possible, and for the use of adjuvant therapy post-transplantation. Future trends include the refinement of positive selection methods, negative selection by taking advantage of the different stromal adhesiveness of the benign and malignant progenitors, or the use of autologous natural killer cells, antisense oligodeoxynucleotides, or specific antibodies to the bcr/abl junction region, and retroviral marking to determine the origin of relapse in autologous transplantation.

Automated enumeration of CD34+ cells in peripheral blood and bone marrow

We have developed a rapid and accurate method to enumerate the number of CD34+ cells in peripheral blood, bone marrow, and leukopheresis samples. The method consists of a two-tube assay and a dedicated software program for data acquisition and analysis. The first reagent combination consists of (a) a nucleic acid dye to identify nucleated cells, (b) a CD45 monoclonal antibody labeled with PE/CY5 to discriminate progenitor cells from mature lymphoid, neutrophil, erythroid, and monocytic cells, (c) an IgG1 control antibody labeled with PE to establish the boundary between specific and nonspecific staining, and (d) a known number of fluorescent beads to determine an absolute count of cells. In the second reagent combination the IgG1 control antibody is replaced by a CD34 antibody labeled with PE that is used to identify the CD34+ cells in the location established by the control reagent combination. The software program uses the fluorescent beads to adjust the forward light scatter, orthogonal light scatter, and three fluorescence detectors of the flow cytometer. The expected location of the CD34+ cells is then established with the control reagent combination followed by the enumeration of the CD34+ cells per microliter of sample with the reagent combination containing the CD34 antibody. This method is sensitive enough to detect CD34+ cells in peripheral blood of normal donors and can reliably determine an increase in CD34+ cells in the peripheral blood of patients treated with chemotherapy and/or growth factors. The method alleviates some of the difficulties encountered when small numbers of CD34+ cells are enumerated. The system allows for more precise evaluations of the grafts used for bone marrow transplantation.

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.

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.

Molecular analysis of retroviral transduction in chronic myelogenous leukemia

We have developed a polymerase chain reaction (PCR) assay for detection of integrated retroviral transgenomes containing the neo G418 resistance gene in colonies (40 cells or more) grown in G418 selection after exposure to the neo-positive retrovirus LNL6. This assay also provides for simultaneous characterization of these colonies as belonging to a chronic myelogenous leukemic (bcr-abl positive) or nonleukemic population (bcr-abl negative). Using these techniques, we assessed transduction of the LNL6 retrovirus into the normal and leukemic cells of a blast-crisis chronic myelogenous leukemia (CML) patient. This work was designed to support the use of the LNL6 retroviral marker to help identify the origin of relapse after autologous marrow infusion. The data from these experiments show that the majority of CML blast crisis cells that, following exposure to the LNL6 virus, produce colonies under rigorous G418 selection are indeed transduced by the virus, as shown by the presence of the neo retroviral gene. Most of these colonies are also shown to be leukemic by PCR detection of the bcr-abl RNA. This demonstrates the feasibility of the study of CML marrow for retroviral marking. These procedures will be of use in establishing if relapse arises from leukemic blasts which contaminate purged autologous bone marrow infused following intensive therapy for leukemia.