Prognosis and prognostic factors for patients with chronic myeloid leukemia: Nontransplant therapy

A predictive scoring system for therapy-failure in persons with chronic myeloid leukemia receiving initial imatinib therapy

Data from 1,364 consecutive subjects with chronic-phase chronic myeloid leukemia (CML) receiving initial imatinib-therapy were interrogated to identify co-variates predicting therapy failure. Subjects were randomly divided into training (n = 908) and validation datasets (n = 456). In the training dataset, WBC count ≥120 × 10E + 9/L, haemoglobin concentration <115 g/L, blood basophils ≥12% and European Treatment and Outcome Study for CML Long-Term Survival (ELTS) risk score were significantly-associated with failure-free survival (FFS). Each co-variate was assigned 1 point to develop the imatinib-therapy failure (IMTF) model except ELTS high-risk category which was assigned 2 points based on multi-variable regression coefficients. Area under receiver-operator characteristic curve values in the IMTF model for 1-, 3- and 5-year FFS were 0.79-0.84 in the training dataset and 0.78-0.85 in the validation dataset. Calibration plots showed high agreement between predicted and observed outcomes. Decision curve analyses indicated subjects benefited from clinical use of this model. Cumulative incidences of imatinib-therapy failure and probabilities of FFS among the 5 risk cohorts (very low-, low-, intermediate-, high- and very high-risk) using the IMTF model were significantly different (all p values < 0.001). The IMTF model also correlated with probabilities of progression-free survival and survival (all p values < 0.001). These data should help physicians optimize TKI-therapy strategy at diagnosis in persons with chronic phase CML.

Intelligent Techniques Using Molecular Data Analysis in Leukaemia: An Opportunity for Personalized Medicine Support System

The use of intelligent techniques in medicine has brought a ray of hope in terms of treating leukaemia patients. Personalized treatment uses patient's genetic profile to select a mode of treatment. This process makes use of molecular technology and machine learning, to determine the most suitable approach to treating a leukaemia patient. Until now, no reviews have been published from a computational perspective concerning the development of personalized medicine intelligent techniques for leukaemia patients using molecular data analysis. This review studies the published empirical research on personalized medicine in leukaemia and synthesizes findings across studies related to intelligence techniques in leukaemia, with specific attention to particular categories of these studies to help identify opportunities for further research into personalized medicine support systems in chronic myeloid leukaemia. A systematic search was carried out to identify studies using intelligence techniques in leukaemia and to categorize these studies based on leukaemia type and also the task, data source, and purpose of the studies. Most studies used molecular data analysis for personalized medicine, but future advancement for leukaemia patients requires molecular models that use advanced machine-learning methods to automate decision-making in treatment management to deliver supportive medical information to the patient in clinical practice.

Standard treatment of Ph+ CML in 2010: how, when and where not to use what BCR/ABL1 kinase inhibitor?

Chronic myeloid leukaemia (CML) is a haematopoietic neoplasm characterised by the BCR/ABL1 oncoprotein. In chronic phase CML, the neoplastic clone exhibits multilineage differentiation and maturation capacity. The BCR/ABL1 kinase blocker imatinib shows major antileukaemic effects in most patients and is considered standard frontline therapy. However, not all patients have a long-lasting response to imatinib. Notably, resistance to imatinib has been recognised as an emerging problem and challenge in CML. Whereas CML stem cells are considered to exhibit intrinsic resistance, acquired resistance may, in addition, develop in subclones over time, resulting in an overt relapse. A key trigger of resistance in subclones are BCR/ABL1 mutations. For such patients, novel multikinase inhibitors such as nilotinib, dasatinib, bosutinib or bafetinib, which block the kinase activity of various BCR/ABL1 mutants, have been developed and reportedly exert antileukaemic effects in drug-resistant cells. For highly resistant patients, haematopoietic stem cell transplantation is an alternative option. Treatment decisions and the selection of drugs are based on the presence and type of BCR/ABL1 mutation(s), phase of disease, other disease-related variables and patient-related factors including age, compliance and co-morbidity. The current review provides an overview on standards in the diagnosis and therapy in CML, with special reference to novel BCR/ABL1 inhibitors.

Predicting the response of CML patients to tyrosine kinase inhibitor therapy

Tyrosine kinase inhibitor (TKI) therapy has significantly changed the treatment paradigm for patients with chronic myeloid leukemia (CML). The first-generation inhibitor, imatinib, has demonstrated remarkable efficacy in most chronic-phase patients. Disease progression remains a significant risk for the first 2 to 3 years of TKI therapy, but the risk falls significantly thereafter. Early recognition of each individual's risk of progression may facilitate a customized approach to TKI therapy. Using such an approach, drug selection and treatment intensity would be adjusted on the basis of each patient's disease profile. Currently available prognostic indicators have limited value in the setting of the potent kinase inhibition afforded by TKIs. Furthermore, these indicators provide little guidance regarding optimal drug choice and dose intensity. In the future, assays that directly assess the efficacy of the protein-drug interaction, taking into account factors intrinsic to the patient and the amount of drug freely available in the plasma, are likely to be of greater value.

Development of a predictive population survival model according to the cytogenetic response rate for patients with chronic myeloid leukemia in the chronic phase

This study sets out to investigate whether the proportion of patients with chronic myeloid leukemia (CML) in the chronic phase who achieve a major cytogenetic response (MCR) can be used as the basis for estimating long-term survival through the use of modeling. Data from seven randomized controlled trials of drugs to treat patients with CML in the chronic phase were used to explore the association between MCR and survival by way of regression analysis. The estimated weighted odds ratio for the survival of those who achieved an MCR when compared with those who did not was 7 (95% CI 5 - 11) at 2 years and 5 (95% CI 3 - 8) at 4 years. Four long-term survival models were subsequently constructed. All models were found to be robust to variations in the data included. Model D was favored using the 'Ockham's razor' principle; it suggests that the median survival may be increased by 1.8 years for every 25 percentage point increase in MCR rate. The results support the use of the proportion of patients with CML in the chronic phase with an MCR to estimate overall long-term survival.

Natural history of Southeast Asian chronic myeloid leukemia patients with different BCR-ABL gene variants

Little evidence exists regarding the prognostic impact of the major BCR-ABL gene variants (e13a2 and e14a2) in chronic myeloid leukemia (CML) patients diagnosed and treated in the developing Asian countries. In this study, 139 Thai CML patients were followed for a median period of 3 years (range 18-43 months). Clinical presentations of both BCR-ABL gene variant groups (73% e14a2+ and 27% e13a2+) were similar, although e14a2+ patients tended to be older (42 vs. 37 years) and had higher white blood cell counts than e13a2+ patients. The majority of patients in both groups presented with Sokal stage 2-3 (score >0.8) and were categorized as Hasford's intermediate- to high-risk groups (score >780). All patients received oral chemotherapy and 13% underwent allogeneic stem cell transplantation. None received oral tyrosine kinase inhibitors. In the conventional chemotherapy group, the overall survival (OS) rate was slightly better in e14a2+ than in e13a2+ patients (p = n.s.). The median survival in e14a2+ and e13a2+ patients who did not receive stem cell transplantation was 49 and 33 months, respectively (p = n.s.). The type of blastic crisis in e14a2+ and e13a2+ patients was similar, being predominantly myeloid. In conclusion, CML patients in Thailand, despite being much younger, had a comparable OS with those in the Western countries, with no different OS between e14a2+ and e13a2+ patients. Future studies should focus on the impact of novel oral BCR-ABL tyrosine kinase inhibitors on the outcome of Thai CML patients with different BCR-ABL gene variants.

Fluorescent in situ hybridization in the diagnosis, prognosis, and treatment monitoring of chronic myeloid leukemia

The unique molecular characteristic of chronic myeloid leukemia (CML), the disease-causing ABL (9q34) to BCR (22q11) translocation, has provided an invaluable tool for disease diagnosis and monitoring of treatment response. The traditional standard in this regard is bone marrow karyotype, also known as conventional cytogenetics (CC), which reveals a shortened chromosome 22, the Philadelphia chromosome, t(9;22)(q34;q11). CC in CML has also been effectively used for monitoring the response to drug therapy. However, this particular laboratory test misses submicroscopic BCR/ABL translocations and is suboptimal for minimal residual disease (MRD) assessment. Both fluorescence in situ hybridization (FISH) and reverse-transcriptase polymerase chain reaction (RT-PCR) feature higher sensitivity in terms of both diagnosis and MRD assessment in CML, compared to CC. Another advantage of these alternative tests is their effective applicability to peripheral blood specimens. The current review highlights the practical literature with respect to the use of FISH for CML whereas the use of RT-PCR has been extensively covered in recent communications.

Quantitative molecular monitoring of BCR-ABL and MDR1 transcripts in patients with chronic myeloid leukemia during Imatinib treatment

Different mechanisms could sustain Imatinib resistance, including overexpression of MDR1, a gene already known to be responsible for multidrug resistance in other hematologic malignancies. In search for a possible correlation, BCR-ABL and MDR1 expression were measured in 115 serial bone marrow samples from 33 CML patients during Imatinib treatment. All patients achieved complete hematologic responses, and 22 patients also achieved complete cytogenetic responses, with median BCR-ABL mRNA values significantly lower than those observed in the group of cases that were persistently Philadelphia positive. All three cases treated during the accelerated phase showed disease progression after an initial period of remission; all presented either increased levels of BCR-ABL or MDR1 3 months before clinical progression. In the subgroup of cases treated during the chronic phase, BCR-ABL and MDR1 levels were significantly correlated after 3 and 6 months (88 and 80%, respectively) but not after 12 months of treatment (32%). Reported data maintain that MDR1 expression would play an important role in Imatinib resistance when the disease is not fully controlled (e.g., progressive disease or during the first months of treatment).

Combination of Imatinib Mesylate with Autologous Leukocyte-Derived Heat Shock Protein and Chronic Myelogenous Leukemia

PURPOSE

To test the feasibility, safety, immunogenicity, and clinical efficacy of an autologous vaccine of leukocyte-derived heat shock protein 70-peptide complexes (Hsp70PC), in conjunction with imatinib mesylate, in patients with chronic myeloid leukemia (CML) in chronic phase.

EXPERIMENTAL DESIGN

Patients had cytogenetic or molecular evidence of disease, despite treatment with imatinib mesylate for all except one patient, at the beginning of study. Hsp70PCs were purified from the leukopheresed peripheral blood mononuclear cells and were administered in eight weekly intradermal injections at 50 microg/dose without adjuvant. Clinical responses were assessed by bone marrow analysis before and after vaccinations. An IFN-gamma enzyme-linked immunospot assay was used to estimate the effect of treatment on natural killer cells and T cells against CML.

RESULTS

Twenty patients were treated. The manufacturing of Hsp70PCs was successful and the administration was safe for all patients. Minimal or no side effects were reported. Clinical responses were seen in 13 of 20 patients as measured by cytogenetic analysis of bone marrow Philadelphia chromosome-positive cells in metaphases and/or, when possible, the level of Bcr/Abl transcript by PCR. Immunologic responses were observed in 9 of 16 patients analyzed, characterized by an increase in the frequency of CML-specific IFN-gamma-producing cells and IFN-gamma-secreting natural killer cells in the blood. A significant correlation between clinical responses and immunologic responses was observed.

CONCLUSIONS

Autologous Hsp70PC vaccination is feasible and safe. When combined with imatinib mesylate, it is associated with immunologic and possible clinical responses against CML in chronic phase.

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.

Chronic myeloid leukemia: pathophysiology, diagnostic parameters, and current treatment concepts

Chronic myeloid leukemia (CML) is a stem cell disease characterized by excessive accumulation of clonal myeloid (precursor) cells in hematopoietic tissues. CML cells display the translocation t(9; 22) that creates the bcr/abl oncogene. The respective oncoprotein (= BCR/ABL) exhibits constitutive tyrosine kinase activity and promotes growth and survival in CML cells. Clinically, CML can be divided into three phases: the chronic phase (CP), the accelerated phase (AP), and the blast phase (BP) that resembles acute leukemia. Progression to AP and BP is associated with occurrence of additional genetic defects that cooperate with bcr/abl in leukemogenesis and lead to resistance against antileukemic drugs. The prognosis in CML is variable depending on the phase of disease, age, and response to therapy. The only curative approach available to date is stem cell transplantation. For those who cannot be transplanted, the BCR/ABL tyrosine kinase inhibitor STI571 (Glivec, Imatinib), interferon-alpha (with or without ARAC), or other cytoreductive drugs are prescribed. Currently available data show that STI571 is a superior compound compared to other drugs in producing complete cytogenetic and molecular responses. However, despite superior initial data and high expectations for an effect on survival, long term results are not available so far, and resistance against STI571 has been reported. Forthcoming strategies are therefore attempting to prevent or counteract STI571 resistance by co-administration of other antileukemic drugs. Whether these strategies will lead to curative drug therapy in CML in the future remains at present unknown.

Randomized comparison of interferon alpha and hydroxyurea with hydroxyurea monotherapy in chronic myeloid leukemia (CML-study II): prolongation of survival by the combination of interferon alpha and hydroxyurea

The optimum treatment conditions of interferon (IFN) alpha therapy in chronic myeloid leukemia (CML) are still controversial. To evaluate the role of hydroxyurea (HU) for the outcome of IFN therapy, we conducted a randomized trial to compare the combination of IFN and HU vs HU monotherapy (CML-study II). From February 1991 to December 1994, 376 patients with newly diagnosed CML in chronic phase were randomized. In all, 340 patients were Ph/BCR-ABL positive and evaluable. Randomization was unbalanced 1:2 in favor of the combination therapy, since study conditions were identical to the previous CML-study I and it had been planned in advance to add the HU patients of study I (n=194) to the HU control group. Therefore, a total of 534 patients were evaluable (226 patients with IFN/HU and 308 patients with HU). Analyses were according to intention-to-treat. Median observation time of nontransplanted living patients was 7.6 years (7.9 years for IFN/HU and 7.3 years for HU). The risk profile (new CML score) was available for 532 patients: 200 patients (38%) were low, 239 patients (45%) intermediate, and 93 patients (17%) high risk. Complete hematologic response rates were higher in IFN/HU-treated patients (59 vs 32%). Of 169 evaluable IFN/HU-treated patients (75%), 104 patients (62%) achieved a cytogenetic response that was complete in 12% (n=21), major in 14% (n=24), and at least minimal in 35% (n=59). Of the 534 patients, 105 (20%) underwent allogeneic stem cell transplantation in first chronic phase. In the low-risk group, 65 of 200 patients were transplanted (33%), 30 (13%) in the intermediate-risk group, and nine (10%) in the high-risk group. Duration of chronic phase was 55 months for IFN/HU and 41 months for HU (P<0.0001). Median survival was 64 months for IFN/HU and 53 months for HU-treated patients (P=0.0063). We conclude that IFN in combination with HU achieves a significant long-term survival advantage over HU monotherapy. In view of the data of CML-study I, these results suggest that IFN/HU is also superior to IFN alone. HU should be combined with IFN in IFN-based therapies and for comparisons with new therapies.

Advances in targeted therapy for chronic myeloid leukemia

Despite the lack of long-term survival data, the impressive results obtained with imatinib mesylate (Gleevec) therapy and the lack of serious adverse events have significantly altered the management of patients with chronic myeloid leukemia. Nevertheless, a large proportion of patients with more advanced disease will develop resistance to imatinib mesylate monotherapy. To prevent the development of resistance, an understanding of the pathophysiology of chronic myeloid leukemia, including the signaling pathways that are activated by the BCR-ABL fusion protein, and the mechanisms of resistance to imatinib are required. This review summarizes the pathogenesis of chronic myeloid leukemia and the potential therapeutic impact of small molecule inhibitors that target pathways critical to the growth or survival of the leukemic cells in patients with chronic myeloid leukemia.