Use of a reduced-intensity conditioning regimen for allogeneic transplantation in patients with chronic myeloid leukemia

Stem cell allografting for chronic Myeloid leukemia in the tyrosine kinase era - forgotten but not gone

Due to the remarkable success of tyrosine kinase inhibitors (TKI) in chronic myeloid leukemia (CML), allogeneic stem cell transplantation (alloSCT) is not first-line treatment for delivering durable, long-term survival. Consequently, alloSCT is reserved for patients with TKI-resistant or TKI-intolerant chronic phase CML (CP-CML) and advanced phase CML (AP-CML). Advances in transplant technology, such as high-resolution HLA typing, introduction of reduced intensity conditioning and increased alternative donor availability, coupled with improved supportive care, have significantly reduced transplant-related mortality and expanded the pool of transplant-eligible patients. Refinement of conditioning regimens, innovative use of post-transplant cellular and pharmacological therapies, and judicious post-transplant monitoring are important strategies for reducing risk of relapse. Given its potential to cure, alloSCT will invariably remain a key part of the treatment algorithm. This article reviews the data underpinning the role and outcomes of alloSCT and provides an update on current recommendations.

The Cure of Chronic Myeloid Leukemia: Are We There Yet?

PURPOSE OF REVIEW

A large number of chronic myeloid leukemia (CML) patients receiving tyrosine kinase inhibitors (TKIs) can now enjoy a deep molecular control of the disease and the life span could be approaching that of normal population. The purpose of the review is to evaluate current evidence and if we can talk of a cure.

RECENT FINDINGS

The revolution in the treatment of CML was apparent since the exquisite efficacy of imatinib mesylate, a tyrosine kinase inhibitor, was proven and received approval for newly diagnosed cases in 2001. Subsequent development of second-generation TKIs, nilotinib and dasatinib, has increased our armamentarium. These TKIs, because of their safety and efficacy, are now offered as first-line therapy, thus relegating use of allogeneic transplant to the second line or beyond. It has also been possible to stop TKIs in selected subsets in whom leukemia burden became undetectable and ~ 40% of them remain drug-free for a number of years-treatment-free remission (TFR). Nevertheless, much work needs to be done to eradicate leukemia stem cells as current TKIs appear unable to eradicate leukemia stem cells (LSC). Effective treatment of more advanced phase CML remains elusive. Further efforts to develop newer molecules targeting BCR-ABL and beyond must be continued. Although TKIs have revolutionized treatment of chronic phase CML, longer follow-up is necessary to realize their curative potential. Equally important is to explore newer targets and development of more potent small molecules for eradication of leukemia clone in all patients.

Allogeneic stem cell transplantation in chronic myeloid leukemia patients: Single center experience

Chronic myeloid leukemia (CML) is a myeloproliferative disease which leads the unregulated growth of myeloid cells in the bone marrow. It is characterized by the presence of Philadelphia chromosome. Reciprocal translocation of the ABL gene from chromosome 9 to 22 t (9; 22) (q34; q11.2) generate a fusion gene (BCR-ABL). BCR-ABL protein had constitutive tyrosine kinase activity that is a primary cause of chronic phase of CML. Tyrosine kinase inhibitors (TKIs) are now considered standard therapy for patients with CML. Even though, successful treatment with the TKIs, allogeneic stem cell transplantation (ASCT) is still an important option for the treatment of CML, especially for patients who are resistant or intolerant to at least one second generation TKI or for patients with blastic phase. Today, we know that there is no evidence for increased transplant-related toxicity and negative impact of survival with pre-transplant TKIs. However, there are some controversies about timing of ASCT, the optimal conditioning regimens and donor source. Another important issue is that BCR-ABL signaling is not necessary for survival of CML stem cell and TKIs were not effective on these cells. So, ASCT may play a role to eliminate CML stem cells. In this article, we review the diagnosis, management and treatment of CML. Later, we present our center’s outcomes of ASCT for patients with CML and then, we discuss the place of ASCT in CML treatment in the TKIs era.

Pushing the envelope-nonmyeloablative and reduced intensity preparative regimens for allogeneic hematopoietic transplantation

Allogeneic hematopoietic cell transplantation (HCT) was originally developed to allow delivery of myeloablative doses of chemotherapy and radiotherapy. With better understanding of disease pathophysiology, the graft vs malignancy (GVM) effect of allogeneic hematopoietic transplantation and toxicities associated with myeloablative conditioning (MAC) regimens, the focus shifted to developing less toxic conditioning regimens to reduce treatment-related morbidity without compromising survival. Although HCT with MAC is preferred to reduced intensity conditioning (RIC) for most patients ⩽60 years with AML/myelodysplastic syndrome and ALL, RIC and nonmyeloablative (NMA) regimens allow HCT for many otherwise ineligible patients. Reduced intensity preparative regimens have produced high rates of PFS for diagnoses, which are highly sensitive to GVM. Relapse of the malignancy is the major cause of treatment failure with RIC/NMA HCT. Incorporation of novel agents like bortezomib or lenalidomide, addition of cellular immunotherapy and use of targeted radiation therapies could further improve outcome. In this review, we discuss commonly used RIC/NMA regimens and promising novel regimens.

The role of stem cell transplantation for chronic myelogenous leukemia in the 21st century

The introduction of tyrosine kinase inhibitors (TKIs), a treatment of chronic myelogenous leukemia (CML), has largely replaced curative strategies based on allogeneic stem cell transplantation (SCT). Nevertheless, SCT still remains an option for accelerated/blastic-phase and selected chronic-phase CML. Transplant outcomes can be optimized by peritransplant TKIs, conditioning regimen, BCR-ABL monitoring, and relapse management. Controversies exist in transplant timing, pediatric CML, alternative donors, and economics. SCT continues to serve as a platform of "operational cure" for CML with TKIs and immunotherapies.

Indications and outcomes of reduced-toxicity hematopoietic stem cell transplantation in adult patients with hematological malignancies

Hematopoietic stem cell transplantation (HCT) utilizing non-myeloablative (NMA) and reduced-intensity conditioning (RIC) regimens (collectively referred to as reduced-toxicity HCT, RT-HCT) has become a viable therapeutic option for patients with hematological malignancies who are ineligible for standard myeloablative conditioning transplantation (MA-HCT). RT-HCT has been shown to induce stable engraftment with low toxicity, and to produce similar overall and progression-free survival (PFS) when compared to MA-HCT in acute myeloid leukemia and myelodysplastic syndrome. The best results for RT-HCT have been reported for patients with disease that is in remission, indolent and chemosensitive, and with a strong graft-versus-malignancy effect. Chronic graft-versus-host disease seems to correlate with a lower relapse rate and better PFS. RT-HCT is inferior when performed in poor risk or advanced disease, due to high relapse rates. A search for novel strategies that includes the most appropriate conditioning regimens and post-transplant immunomodulation protocols with more intensive anti-malignancy activity but limited toxicity is in progress. This review provides an update on the results of clinical studies of RT-HCT, and discusses possible indications and investigative strategies for improving the clinical outcomes of RT-HCT for the major hematological malignancies.

Chronic myelogenous leukemia: role of stem cell transplant in the imatinib era

In the pre-tyrosine kinase (TKI) era, allogeneic stem cell transplant (allo-SCT) was the front-line treatment of choice for young patients with chronic myelogenous leukemia (CML). Today, imatinib is well established as front-line therapy for CML, with excellent long-term outcomes. This has changed the role of allo-SCT and the number of patients undergoing allo-SCT has declined dramatically. Allo-SCT is currently recommended for patients in accelerated/blast phase disease, those who have failed a second-generation TKI and those with TKI-resistant mutations such as T315I. The role of allo-SCT in the management of CML will require continual reappraisal as medical therapies continue to evolve.

Case-matched comparison with standard versus reduced intensity conditioning regimen in chronic myeloid leukemia patients

This retrospective case-matched study evaluated the efficacy of reduced intensity conditioning (RIC) regimen on early and late allogeneic transplant outcome in chronic myeloid leukemia (CML) patients. Twenty-eight patients conditioned with RIC regimen were matched to 56 patients who received a myeloablative conditioning (MAC) regimen. The main criteria for case matching among our CML allotransplant cohort were the Gratwohl scoring system. The median score was 2 (1-4) in each group. The pretransplant disease status was first chronic phase (CP1, n = 20), CP2 (n = 2), and advanced phase (n = 6) in RIC, and CP1 (n = 46), CP2 (n = 3), and advanced phase (n = 7) in MAC. The duration of neutropenia and thrombocytopenia was shorter in RIC than MAC. The grade and duration of mucositis were less in RIC. The need for total parenteral nutrition (21% vs. 77%, p < 0.0001) and febrile neutropenic episodes (50% vs. 95%, p < 0.0001) were observed less frequently in RIC compared with MAC-given patients. Acute or chronic graft versus host diseases (GvHD) were not affected by the intensity of conditioning regimen. The incidence of transplant-related mortality was higher in MAC (7% vs. 14%, p = 0.01). Although more relapse/progression was observed in the RIC group, the probability of 5- and 10-year leukemia-free- and overall survival were similar regardless of conditioning regimen intensity (p > 0.05). In early first CP, the pair of female donor-male recipient and the development of chronic GvHD prolonged both leukemia-free survival and overall survival in multivariate analysis. According to our single-center matched-pair analysis, the use of RIC regimens in patients with low-risk CML results with toxicities less, responses later, and relapses more frequent than the MAC regimens.

Stem cells in clinical practice: applications and warnings

Stem cells are a relevant source of information about cellular differentiation, molecular processes and tissue homeostasis, but also one of the most putative biological tools to treat degenerative diseases. This review focuses on human stem cells clinical and experimental applications. Our aim is to take a correct view of the available stem cell subtypes and their rational use in the medical area, with a specific focus on their therapeutic benefits and side effects. We have reviewed the main clinical trials dividing them basing on their clinical applications, and taking into account the ethical issue associated with the stem cell therapy.

Clinical outcomes and direct hospital costs of reduced-intensity allogeneic transplantation in chronic myeloid leukemia

A reduced-intensity conditioning allogeneic stem cell transplantation was given to 19 patients (aged 15-59 years) in the first chronic phase and one patient in the accelerated phase with chronic myeloid leukemia (CML) after a regimen consisting of fludarabine (Flu), busulfan (Bu) and ATG Fresenius. The median follow-up was 27 months. Until day +100, no transplant-related mortality was recorded. The incidence of acute and chronic graft-versus-host disease (GvHD) was 55 and 75%, respectively. Two patients (10%) died from GvHD. Fourteen (70%) patients achieved molecular remission. Additional post-transplant intervention (donor lymphocyte infusion, imatinib) was necessary, however, in 10 patients (50% of the patients; non-achievement of stable molecular remission or later relapses). The total direct cost of the transplantation treatment for all of the patients came to 1,572,880 euro. If the patients had been treated with imatinib and followed-up with the same time period as they were following a transplantation, the direct cost of the imatinib treatment would have been 2,005,117 euro. The transplantation treatment appears to be less expensive after approximately 2 years of follow-up. Flu+Bu+ATG is a low-toxicity regimen for patients with CML. However, a close follow-up is necessary and about 50% of the patients require further therapeutic intervention.

The early referral for reduced-intensity stem cell transplantation in patients with Ph1 (+) chronic myelogenous leukemia in chronic phase in the imatinib era: results of the Latin American Cooperative Oncohematology Group (LACOHG) prospective, multicenter study

Using a reduced-intensity stem cell transplantation (RIST) schedule, 24 patients with Philadelphia (Ph1) (+) chronic myelogenous leukemia (CML) in first chronic phase (CP) were prospectively allografted in four Latin American countries: México, Brazil, Colombia and Venezuela, using HLA-identical siblings as donors. The median age of the patients was 41 years (range 10-71 years); there were eight females. Patients received a median of 4.4 x 10(6)/kg CD34 cells. The median time to achieve above 0.5 x 10(9)/l granulocytes was 12 days, range 0-41 days, and the median time to achieve above 20 x 10(9)/l platelets was also 12 days, range 0-45 days. In all, 22 patients are alive 81-830 (median 497) days after RIST. The 830-day probability of survival is 92%, and the median survival has not been reached, being beyond 830 days. A total of 11 patients (46%) developed acute graft-versus-host disease (GVHD), and seven of 23 (30%) developed chronic GVHD. Two patients died 43 and 210 days after RIST, one as a result of sepsis and the other of chronic GVHD. The 100-day mortality was 4.4%, and transplant-related mortality was 8%. RIST for patients with CML in CP appears to be an adequate therapeutic option.

Stem cell transplantation in patients with chronic myelogenous leukemia: when should it be used?

Hematopoietic stem cell transplantation has been a cornerstone of therapy for chronic myelogenous leukemia (CML) for more than 15 years and is still a standard treatment option for patients with CML. The advent of imatinib mesylate, an inhibitor of the molecular defect driving CML, the BCR-ABL tyrosine kinase, has rewritten treatment algorithms for this disease and has shifted focus away from allografting. Despite advances in stem cell transplantation, such as broader availability with the use of modified conditioning regimens, use of allografting has diminished. Also, the nearly universal patient exposure to imatinib or other kinase inhibitors before transplantation may affect the biology of the disease that is currently being treated with an allograft and ultimately may affect outcomes. Exceedingly high rates of meaningful and stable response with longer follow-up continue to drive enthusiasm for imatinib use, and understanding of resistance mechanisms has driven rapid investigation of second-generation tyrosine kinase inhibitors to address imatinib failure and suboptimal response. In most patients, imatinib reduces CML to a minimal residual disease state in which options to further deepen remission, such as immunotherapy, are sought; monitoring techniques and interpretation of response advance in parallel to meet demands; and uncertainty remains as a new natural history of CML is defined in an era of kinase inhibitor therapy. This review summarizes the state of transplant and nontransplant therapy for CML and discusses the decision making for patients with an aim to optimize the use of our best therapies for CML in an era of uncertainty.

Quo vadis haemapheresis. Current developments in haemapheresis

The techniques of haemapheresis originated in the development of centrifugal devices separating cells from plasma and later on plasma from cells. Subsequently membrane filtration was developed allowing for plasma-cell separation. The unspecificity of therapeutic plasma exchange led to the development of secondary plasma separation technologies being specific, semi-selective or selective such as adsorption, filtration or precipitation. In contrast on-line differential separation of cells is still under development. Whereas erythrocytapheresis, granulocytapheresis, lymphocytapheresis and stem cell apheresis are technically advanced, monocytapheresis may need further improvement. Also, indications such as erythrocytapheresis for the treatment of polycythaemia vera or photopheresis though being clinically effective and of considerable importance for an appropriate disease control are to some extent under debate as being either too costly or without sufficient understanding of the mechanism. Other forms of cell therapy are under development. Rheohaemapheresis as the most advanced technology of extracorporeal haemorheotherapy is a rapidly developing approach contributing to the treatment of microcirculatory diseases and tissue repair. Whereas the control of a considerable number of (auto-) antibody mediated diseases is beyond discussion, the indication of apheresis therapy for immune complex mediated diseases is quite often still under debate. Detoxification for artificial liver support advanced considerably during the last years, whereas conclusions on the efficacy of septicaemia treatment are debatable indeed. LDL-apheresis initiated in 1981 as immune apheresis is well established since 24 years, other semi-selective or unspecific procedures, allowing for the elimination of LDL-cholesterol among other plasma components are also being used. Correspondingly Lp(a) apheresis is available as a specific, highly efficient elimination procedure superior to techniques which also eliminate Lp(a). Quality control systems, more economical technologies as for instance by increasing automation, influencing the over-interpretation of evidence based medicine especially in patients with rare diseases without treatment alternative, more insight into the need of controlled clinical trials or alternatively improved diagnostic procedures are among others tools ways to expand the application of haemapheresis so far applied in cardiology, dermatology, haematology, immunology, nephrology, neurology, ophthalmology, otology, paediatrics, rheumatology, surgery and transfusion medicine.

Managing the Patient with Chronic Myeloid Leukemia Through and After Allogeneic Stem Cell Transplantation

Although the only curative therapy for chronic myeloid leukemia remains allogeneic stem cell transplantation (allo-SCT), early to mid-term results of imatinib in newly diagnosed patients are sufficiently impressive to have displaced allo-SCT to second- or third-line treatment. Patients now arrive at a decision for transplantation in a variety of disease situations: failing to achieve certain hematological, cytogenetic and molecular milestones by some pre-determined timepoint, having lost a previous best response or by progression to advanced phase. The decision, therefore, is not simply whether to transplant or not, but also how to transplant. Evolving transplant technology requires that the individual circumstances of each patient should be considered when recommending the procedure. Attempts to improve the safety of transplant are generally associated with a reduction in long-term disease control and patient monitoring, and management is life-long. The treatment of recurrent disease is no longer straightforward, with the choices being donor lymphocytes or tyrosine kinase inhibitors alone or in combination. This section will review the evidence supporting some of these decisions and highlight current controversies.

The hope and the reality of reduced intensity transplants in children with malignant diseases

Reduced intensity preparative regimens are increasingly used for conditioning prior to allogeneic stem cell transplantation. As opposed to classical methods of pre-transplant conditioning, patients receive predominantly immunosuppressive therapies that facilitate early engraftment, while cells within the graft itself promote continuation of the engraftment process. Despite early hopes that this form of transplant would be devoid of grade III and IV acute toxicities, there is a substantial amount of short-term morbidity associated with the technique. Although long-term follow-up is not yet available, it is hoped that these regimens will spare young patients many of the late effects (cataracts, growth retardation, endocrine and reproductive problems) that are often associated with classical pre-transplant conditioning regimens. Reliable engraftment and leukemic control have been demonstrated in a large number of both adult and pediatric transplant recipients of these regimens, many of whom were deemed at high risk for standard conditioning because of serious co-morbidities, previous autologous transplantation or multiply relapsed disease. A brief review of the state of the art of this technology as it applies to pediatric transplantation is presented. Preliminary results of a survey of pediatric transplant centers indicate that a variety of protocols are used for a variety of indications. The use of standardized criteria for implementation of reduced intensity preparative regimens, the use of a limited number of regimens, and more extensive data collection will permit the elaboration of prospective comparative studies of this new and exciting modality.

Hematopoietic cell transplantation from HLA-identical sibling donors after low-dose radiation-based conditioning for treatment of CML

A total of 24 patients (median age 58; range, 27-71 years) with chronic myeloid leukemia (CML) in first chronic (CP1) (n=14), second chronic (n=4), or accelerated phase (n=6) who were not candidates for conventional hematopoietic cell transplantation (HCT), received nonmyeloablative HCT from HLA-matched siblings a median of 28.5 (range, 11-271) months after diagnosis. They were conditioned with 2 Gy total body irradiation (TBI) alone (n=8) or combined with fludarabine, 90 mg/m(2) (n=16). Postgrafting immunosuppression included cyclosporine and mycophenolate mofetil. All patients initially engrafted. However, 4 of 8 patients not given fludarabine experienced nonfatal rejection while all others had sustained engraftment. With a median follow-up of 36 (range, 4-49) months, 13 of 24 patients (54%) were alive and in complete remission. There were five (21%) deaths from nonrelapse mortality, one (4%) during the first 100 days after transplant. The proportions of grade II, III, and IV acute GVHD were 38, 4, and 8%, respectively. The 2-year estimate of chronic GVHD was 32%. The 2-year survival estimates for patients in CP1 (n=14) and beyond CP1 (n=10) were 70 and 56%, respectively. This study shows encouraging remission rates for patients with CML not eligible for conventional allografting.

Chronic myeloid leukemia: current application of cytogenetics and molecular testing for diagnosis and treatment

Chronic myeloid leukemia provides an illustrative disease model for both molecular pathogenesis of cancer and rational drug therapy. Chronic myeloid leukemia is a clonal stem cell disease caused by an acquired somatic mutation that fuses, through chromosomal translocation, the abl and bcr genes on chromosomes 9 and 22, respectively. The bcr/abl gene product is an oncogenic protein that localizes to the cytoskeleton and displays an up-regulated tyrosine kinase activity that leads to the recruitment of downstream effectors of cell proliferation and cell survival and consequently cell transformation. Such molecular information on pathogenesis has facilitated accurate diagnosis, the development of pathogenesis-targeted drug therapy, and most recently the application of molecular techniques for monitoring minimal residual disease after successful therapy. These issues are discussed within the context of clinical practice.

Current indications for reduced-intensity allogeneic stem cell transplantation

Stem cell transplantation preceded by reduced-intensity conditioning (RIC) is based on the use of immunosuppressive agents as the sine qua non to ensure donor cell engraftment. It is a curative option for select patients suffering from haematological and non-haematological malignancies. The most beneficial results are observed when a full donor engraftment is achieved with 'tolerable' graft-vs-host disease (GVHD). To date, a vast amount of clinical data has been published, but in an uncontrolled manner. This review summarizes the currently known outcome of allogeneic transplants with RIC, with every disease category analysed separately. Unresolved problems include the optimal combination of immunosuppressive agents, the degree of infectious complications, and GVHD that may appear in some patients. Directions to overcome these complications are discussed. Despite the paucity of controlled clinical data, the current indications for RIC allogeneic transplantation are summarized based on the best-available phase II data.

Hematopoietic stem cells in chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a malignant myeloproliferative disorder originating from a pluripotent hematopoietic stem cell that acquires a Philadelphia (Ph) chromosome encoding the BCR-ABL oncogenic fusion protein. This molecular abnormality that is thought to be causative in CML was the first acquired chromosome translocation associated with a human malignancy. This chromosomal translocation also makes it possible to precisely distinguish between residual normal (i.e., Ph-, BCR-ABL-) progenitor or stem cells and their leukemic counterpart, Ph+ or BCR-ABL+ progenitor/stem cells in every given sample of a patient with CML. This has provided seminal insights into the molecular and cellular biology of leukemia and also of the process of normal hematopoiesis. CML has become a fascinating model disease for malignancy in general.