Imatinib mesylate dose escalation is associated with durable responses in patients with chronic myeloid leukemia after cytogenetic failure on standard-dose imatinib therapy

Exploring treatment decision-making in chronic myeloid leukemia in chronic phase

The introduction of tyrosine kinase inhibitors (TKIs) has transformed the treatment of chronic myeloid leukemia (CML). Each approved TKI has its own risk-benefit profile, and patients have choices across lines of therapy. Identifying the initial and subsequent treatment that will lead to the best possible outcome for individual patients is challenging. In this review, we summarize data for each approved TKI across lines of therapy in patients with CML in chronic phase, highlighting elements of each agent's safety and efficacy profile that may impact patient selection, and provide insights into individualized treatment sequencing decision-making aimed at optimizing patient outcomes.

Screening and Activity Evaluation of Novel BCR-ABL/T315I Tyrosine Kinase Inhibitors

INTRODUCTION

Chronic myeloid leukemia (CML) is a kind of malignant tumor formed by the clonal proliferation of bone marrow hematopoietic stem cells. BCR-ABL fusion protein, found in more than 90% of patients, is a vital target for discovering anti- CML drugs. Up to date, imatinib is the first BCR-ABL tyrosine kinase inhibitor (TKI) approved by the FDA for treating CML. However, the drug resistance problems appeared for many reasons, especially the T135I mutation, a "gatekeeper" of BCR-ABL. Currently, there is no long-term effective and low side effect drug in clinical.

METHODS

This study intends to find novel TKIs targeting BCR-ABL with high inhibitory activity against T315I mutant protein by combining artificial intelligence technology and cell growth curve, cytotoxicity, flow cytometry and Western blot experiments.

RESULTS

The obtained compound was found to kill leukemia cells, which had good inhibitory efficacy in BaF3/T315I cells. Compound no 4 could induce cell cycle arrest, cause autophagy and apoptosis, and inhibit the phosphorylation of BCR-ABL tyrosine kinase, STAT5 and Crkl proteins.

CONCLUSION

The results indicated that the screened compound could be used as a lead compound for further research to discover ideal chronic myeloid leukemia therapeutic drugs.

Which Second-Line Tyrosine Kinase Inhibitor(s) for Chronic Myeloid Leukemia?

OPINION STATEMENT

In patients with chronic myeloid leukemia who require second-line tyrosine kinase inhibitor therapy, many options exist. These treatments include alternate generation tyrosine kinase inhibitors and in some cases consideration of allogeneic transplant. Although efficacious, each tyrosine kinase inhibitor possesses distinct side effects and pharmacological profiles that prevent a generalizable treatment approach. Furthermore, there is limited head-to-head trial data that would suggest the superiority of one tyrosine kinase inhibitor over another to help guide treatment decisions in specific clinical settings. Therefore, we treat each patient independently. A patient's treatment plan must be personalized by a variety of clinical factors to optimize response and tolerability. Our general approach is to first examine the reason for treatment failure, which may be due to either intolerance or relapse. Second, we consider the age and patient's comorbidities such as lung disease, diabetes, or cardiovascular disease. In patients who have inadequate responses, we analyze the patient's BCR-ABL1 mutational profile, which is beneficial if that patient harbors a specific tyrosine kinase inhibitor responsive mutation, such as T315I. Using these steps, we can provide a generalizable approach to choosing the appropriate second-line tyrosine inhibitor for chronic myeloid leukemia.

Chronic Myeloid Leukemia: 2022 Update on Diagnosis, Therapy and Monitoring

DISEASE OVERVIEW

Chronic Myeloid Leukemia (CML) is a myeloproliferative neoplasm with an incidence of 1-2 cases per 100,000 adults. It accounts for approximately 15% of newly diagnosed cases of leukemia in adults DIAGNOSIS: CML is characterized by a balanced genetic translocation, t (9;22) (q34;q11.2), involving a fusion of the Abelson gene (ABL1) from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11.2. This rearrangement is known as the Philadelphia chromosome. The molecular consequence of this translocation is the generation of a BCR::ABL1 fusion oncogene, which in turn translates into a BCR::ABL1 oncoprotein.

FRONTLINE THERAPY

Four tyrosine kinase inhibitors (TKIs), imatinib, dasatinib, bosutinib, and nilotinib are approved by the United States Food and Drug Administration for first-line treatment of newly diagnosed CML in chronic phase (CML-CP). Clinical trials with second generation TKIs reported significantly deeper and faster responses but had no impact on survival prolongation, likely because of the availability of effective TKIs salvage therapies for patients who have a cytogenetic relapse with frontline TKI therapy.

SALVAGE THERAPY

For CML post failure on frontline therapy, second-line options include second and third generation TKIs. Although potent and selective, these TKIs exhibit unique pharmacological profiles and response patterns relative to different patient and disease characteristics, such as patients' comorbidities, disease stage, and BCR::ABL1 mutational status. Patients who develop the T315I "gatekeeper" mutation display resistance to all currently available TKIs except ponatinib, asciminib, and olverembatinib. Allogeneic stem cell transplantation remains an important therapeutic option for patients with CML-CP and failure (due to resistance) of at least 2 TKIs, and for all patients in advanced phase disease. Older patients who have a cytogenetic relapse post failure on all TKIs can maintain long-term survival if they continue a daily most effective/least toxic TKI, with or without the addition of non-TKI anti-CML agents (hydroxyurea, omacetaxine, azacitidine, decitabine, cytarabine, busulfan, others). This article is protected by copyright. All rights reserved.

The Evolving Landscape of Frontline Therapy in Chronic Phase Chronic Myeloid Leukemia (CML)

PURPOSE OF REVIEW

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm characterized by uncontrolled proliferation of mature and maturing granulocytes. The disease is characterized by the presence of translocation t(9;22) leading to the abnormal BCR-ABL fusion. Historically, treatment options included hydroxyurea, busulfan, and interferon-α (IFN-α), with allogeneic stem cell transplant being the only potential curative therapy. More recently, the development of tyrosine kinase inhibitors (TKIs) has revolutionized the treatment of CML and turned a once fatal disease into a chronic and manageable disorder. This review aims to discuss the frontline treatment options in chronic-phase CML, provide recommendations for tailoring frontline treatment to the patient, and explore emerging therapies in the field.

RECENT FINDINGS

The first-generation TKI, imatinib, was FDA approved in 2001 for use in CML. Following the approval and success of imatinib, second- and third-generation TKIs have been developed providing deeper responses, faster responses, and different toxicity profiles. With numerous options available in the frontline setting, choosing the best initial treatment for each individual patient has become a more complex decision. When choosing a frontline therapy for patients with chronic-phase CML, one should consider disease risk, comorbid conditions, and the goal of therapy.

Atypical activation of signaling downstream of inactivated Bcr-Abl mediates chemoresistance in chronic myeloid leukemia

Chronic myeloid leukemia (CML) epitomises successful targeted therapy, where inhibition of tyrosine kinase activity of oncoprotein Bcr-Abl1 by imatinib, induces remission in 86% patients in initial chronic phase (CP). However, in acute phase of blast crisis, 80% patients show resistance, 40% among them despite inhibition of Bcr-Abl1 activity. This implies activation of either Bcr-Abl1- independent signalling pathways or restoration of signalling downstream of inactive Bcr-Abl1. In the present study, mass spectrometry and subsequent in silico pathway analysis of differentiators in resistant CML-CP cells identified key differentiators, 14-3-3ε and p38 MAPK, which belong to Bcr-Abl1 pathway. Their levels and activity respectively, indicated active Bcr-Abl1 pathway in CML-BC resistant cells, though Bcr-Abl1 is inhibited by imatinib. Further, contribution of these components to resistance was demonstrated by inhibition of Bcr-Abl1 down-stream signalling by knocking-out of 14-3-3ε and inhibition of p38 MAPK activity. The observations merit clinical validation to explore their translational potential.

Chronic Myeloid Leukemia, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

Chronic myeloid leukemia (CML) is defined by the presence of Philadelphia chromosome (Ph) which results from a reciprocal translocation between chromosomes 9 and 22 [t(9;22] that gives rise to a BCR-ABL1 fusion gene. CML occurs in 3 different phases (chronic, accelerated, and blast phase) and is usually diagnosed in the chronic phase. Tyrosine kinase inhibitor therapy is a highly effective first-line treatment option for all patients with newly diagnosed chronic phase CML. This manuscript discusses the recommendations outlined in the NCCN Guidelines for the diagnosis and management of patients with chronic phase CML.

Chronic myeloid leukemia: 2020 update on diagnosis, therapy and monitoring

DISEASE OVERVIEW

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm with an incidence of 1-2 cases per 100 000 adults. It accounts for approximately 15% of newly diagnosed cases of leukemia in adults.

DIAGNOSIS

CML is characterized by a balanced genetic translocation, t(9;22)(q34;q11.2), involving a fusion of the Abelson gene (ABL1) from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11.2. This rearrangement is known as the Philadelphia chromosome. The molecular consequence of this translocation is the generation of a BCR-ABL1 fusion oncogene, which in turn translates into a BCR-ABL oncoprotein.

FRONTLINE THERAPY

Four tyrosine kinase inhibitors (TKIs), imatinib, nilotinib, dasatinib, and bosutinib are approved by the United States Food and Drug Administration for first-line treatment of newly diagnosed CML in chronic phase (CML-CP). Clinical trials with second generation TKIs reported significantly deeper and faster responses, but they had no impact on survival prolongation, likely because of the existence of highly effective salvage therapies for patients who have a cytogenetic relapse with frontline TKI.

SALVAGE THERAPY

For CML post failure on frontline therapy, second-line options include second and third generation TKIs. Although potent and selective, these exhibit unique pharmacological profiles and response patterns relative to different patient and disease characteristics, such as patients' comorbidities, disease stage, and BCR-ABL1 mutational status. Patients who develop the T315I "gatekeeper" mutation display resistance to all currently available TKIs except ponatinib. Allogeneic stem cell transplantation remains an important therapeutic option for patients with CML-CP who have failed at least 2 TKIs, and for all patients in advanced phase disease. Even among older patients who have a cytogenetic relapse post failure on all TKIs, they can maintain long-term survival if they continue on a daily most effective/less toxic TKI, with or without the addition of non-TKI anti-CML agents (hydroxyurea, omacetaxine, azacitidine, decitabine, cytarabine, busulfan, others).

Randomized study of imatinib for chronic myeloid leukemia: comparing standard dose escalation with aggressive escalation

In 2007, we conducted a prospective randomized study to compare an aggressive dose escalation (group B, n = 123) with the standard dose escalation proposed by European LeukemiaNet (group A, n = 122). In group B, if patients did not achieve a complete cytogenetic response (CCyR) at 3 months or did not achieve a major molecular response (MR3) at 6 months, imatinib was increased to 600 mg. At 6 months CCyR was achieved in 69.4% and 78.7% of patients in groups A and B, respectively. The rate of MR3 at 12 months and 24 months were similar in group A (52.1% and 70.0%) and group B (58.7% and 68.3%). The cumulative incidence of withdrawal by failure without accelerated/blast phase was higher in group A than in group B (9.2% vs 2.5% at 24 months). At 3 and 6 months, the protocol called for the imatinib dose to increase to 600 mg in 90 patients (74.4%) in group B. Among the 42 patients who received increased dose according to the protocol, 25 (60.0%) achieved MR3 at 12 months, whereas only 14 (35.0%) of 40 patients who did not receive an increased dose achieved MR3 (P < .05). The number of patients who withdrew from this study was similar (group A, 20%; group B, 21%). The early aggressive dose escalation failed to produce a better molecular response at 12 months. However, for patients who tolerate imatinib well, but show inadequate response at an early time point, aggressive dose escalation may contribute to achieving a better outcome. This study was registered at http://www.umin.ac.jp/ctr/ as #R000000965.

Cost effectiveness of therapeutic drug monitoring for imatinib administration in chronic myeloid leukemia

BACKGROUND

Imatinib mesylate (IM) is a first-line treatment option for patients with chronic myeloid leukemia (CML). Patients who fail or are intolerant to IM therapy are treated with more expensive second and third-generation tyrosine kinase inhibitors. Patients show wide variation in trough concentrations in response to standard dosing. Thus, many patients receive subtherapeutic or supratherapeutic doses. Therapeutic drug monitoring (TDM) may improve dose management that, in turn, may reduce costs and improve outcomes. However, TDM also adds to the cost of patient care. The objective of this study was to determine the cost-effectiveness of TDM for generic IM therapy.

METHODS

We developed a microsimulation model for the trough plasma concentration of IM which is related to a cytogenetic or molecular response. We compared two cohorts: one with TDM and one without TDM (NTDM). The lifetime incremental cost-effectiveness ratio (ICER) was calculated using quality-adjusted life years (QALYs) as the effectiveness measure. One-way and probabilistic sensitivity analyses were performed.

RESULTS

The lifetime cost and QALY of treatment with TDM were $2,137K [95% Ci: 2,079K; 2,174K] and 12.37 [95% CI: 12.07; 12.55], respectively. The cost and QALY of NTDM were $2,132K [95% CI: 2,091K; 2,197K] and 12.23 [95% CI: 11.96; 12.50], respectively. The incremental cost and QALY for TDM relative to NTDM was $4,417 [95% CI: -52,582; 32,097]) and 0.15 [95% CI: -0.13; 0.28]. The ICER for TDM relative to NTDM was $30,450/QALY. Probabilistic sensitivity analysis showed that TDM was cost-effective relative to NTDM in 90% of the tested scenarios at a willingness-to-pay threshold of $100,000/QALY.

CONCLUSIONS

Although the impact of TDM is modest, the cost-effectiveness over a lifetime horizon (societal perspective, ($30,450/QALY) falls within the acceptable range (< $100k/QALY).

Tyrosine kinase inhibitor interruptions, discontinuations and switching in patients with chronic-phase chronic myeloid leukemia in routine clinical practice: SIMPLICITY

SIMPLICITY (NCT01244750) is an observational study exploring tyrosine kinase inhibitor (TKI) use and management patterns in patients with chronic phase-chronic myeloid leukemia in the US and Europe in routine clinical practice. Herein we describe interruptions, discontinuations and switching of TKI therapy during the initial 2 years of treatment among 1121 patients prospectively enrolled between October 1, 2010 and March 7, 2017. Patient characteristics were broadly similar between the imatinib (n = 370), dasatinib (n = 376), and nilotinib (n = 375) cohorts. Treatment interruptions occurred in 16.4% (year 1) and 4.0% (year 2) of patients, mainly attributed to hematologic intolerances. Treatment discontinuations occurred in 21.8% (year 1) and 10.2% (year 2) of patients, with the highest rate within the first 3 months for intolerance. Switching of TKI was seen in 17.8% (year 1) and 9.5% (year 2) of patients. Significant associations were found between TKI switching and female gender (year 1), age ≥65 years at diagnosis (year 2) and treatment with imatinib (year 2). Intolerance was the most common reason given for patients discontinuing and for switching TKI therapy; however resistance was also cited. Lack of response monitoring in routine clinical practice may have resulted in lower identification of resistance in this dataset. Data from SIMPLICITY suggest that, in routine clinical practice, intolerance and resistance to TKIs influence decisions to change treatment. Changes in TKI therapy are frequent, with nearly a third of patients discontinuing their first-line TKI.

Comparative analyses of nilotinib versus high-dose imatinib versus sustained standard-dose imatinib in patients with chronic phase chronic myeloid leukemia following suboptimal molecular response to first-line imatinib

The aim of this study was to investigate the efficacy of nilotinib (NIL) versus high-dose imatinib (IM) versus sustained standard-dose IM for patients with chronic myeloid leukemia (CML) with suboptimal molecular response to first-line IM therapy. Patients with CML who achieved complete cytogenetic response (CCyR) but not major molecular response (MMR) after 18-24 months on first-line IM therapy were enrolled and divided into three treatment cohorts: NIL 800 mg/day (Cohort 1, n = 28) and IM 800 mg/day (Cohort 2, n = 28) in the RE-NICE study, and sustained IM 400 mg/day (Cohort 3, n = 52) in clinical practice. The primary efficacy variable of cumulative rate of MMR by 12 months was not different among the three cohorts. However, the cumulative incidence of MMR by 36 months was significantly higher in Cohort 1 than Cohort 3 (83.1% vs. 57.1%, P = 0.021), but there were no significant differences in Cohort 1 vs. 2 (P = 0.195) and Cohort 2 vs. 3 (P = 0.297). Different profile for adverse events was observed between NIL and high-dose IM therapy. In conclusion, our data suggested that switching to NIL may provide more effective long-term response than sustaining standard-dose IM for patients with suboptimal molecular response to first-line IM.

Chronic myeloid leukemia: 2018 update on diagnosis, therapy and monitoring

DISEASE OVERVIEW

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm with an incidence of 1-2 cases per 100 000 adults. It accounts for approximately 15% of newly diagnosed cases of leukemia in adults.

DIAGNOSIS

CML is characterized by a balanced genetic translocation, t(9;22)(q34;q11.2), involving a fusion of the Abelson gene (ABL1) from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11.2. This rearrangement is known as the Philadelphia chromosome. The molecular consequence of this translocation is the generation of a BCR-ABL1 fusion oncogene, which in turn translates into a BCR-ABL1 oncoprotein. Frontline therapy: Four tyrosine kinase inhibitors (TKIs), imatinib, nilotinib, dasatinib, and bosutinib are approved by the United States Food and Drug Administration for first-line treatment of patients with newly diagnosed CML in chronic phase (CML-CP). Clinical trials with second generation TKIs reported significantly deeper and faster responses; this has not translated into improved long-term survival, because of the availability of effective salvage therapies. Salvage therapy: For patients who fail frontline therapy, second-line options include second and third generation TKIs. Second and third generation TKIs, although potent and selective, exhibit unique pharmacological profiles and response patterns relative to different patient and disease characteristics, such as patients' comorbidities, disease stage, and BCR-ABL1 mutational status. Patients who develop the T315I "gatekeeper" mutation display resistance to all currently available TKIs except ponatinib. Allogeneic stem cell transplantation remains an important therapeutic option for patients with CML-CP who have failed at least 2 TKIs, and for all patients in CML advanced phases.

An economic analysis of high-dose imatinib, dasatinib, and nilotinib for imatinib-resistant chronic phase chronic myeloid leukemia in China: A CHEERS-compliant article

BACKGROUND

The aim of the study was to test the cost-effectiveness of dasatinib compared to high-dose imatinib and nilotinib in Chinese patients who were diagnosed with imatinib-resistant chronic myeloid leukemia in the chronic phase (CML-CP).

METHODS

A Markov model combined with clinical effectiveness, utility, and cost data was used. The sensitivity analyses were conducted to determine the robustness of the model outcomes. The impact of patient assistance programs (PAPs) was assessed.

RESULTS

Treatment with dasatinib is expected to produce 3.65, 0.59, and 0.15 more quality-adjusted life years (QALYs) in comparison with high-dose imatinib (600 and 800 mg) and nilotinib, respectively. When a PAP was available, dasatinib yielded an incremental cost of $16,417 per QALY compared to imatinib (600 mg) and was cost-saving compared to imatinib (800 mg) and nilotinib.

CONCLUSION

When PAP is available in the Chinese setting, dasatinib is likely to be a cost-effective strategy for patients with CML-CP standard-dose imatinib resistance. The results should be carefully explained due to the assumptions and limitations used in the study.

Use patterns of first-line inhibitors of tyrosine kinase and time to change to second-line therapy in chronic myeloid leukemia

Background Chronic myeloid leukemia (CML) has a low incidence but a high burden of disease, and is treated with high-cost tyrosine kinase inhibitors (TKI). Objective To determine the time from the start of a first-line TKI until it passes to second-line, and to establish the reasons for the change of therapy time. Setting Patients with Philadelphia-positive CML treated with some TKI. Methods Retrospective cohort study, between January 1 2007 and July 31 2015, with information obtained from medical records, the time to change initial drugs to secondline therapy, and the reasons for change, were identified. Kaplan-Meier survival analysis was carried out. Main outcome measure A change in therapy to the secondline TKI and the final reason for the change of therapy. Results A total of 247 patients treated were found in 22 cities in Colombia with a mean age of 53.2 ± 15.2 years. The drug most used as initial therapy was imatinib; 53.8% of cases had to change to another TKI. 50% of patients changed therapy in 42 months, men in 24 and women in 67 months (95% CI 14.314-33.686; p = 0.001). Being male (OR 2.23; 95% CI 1.291-3.854; p = 0.004) and receiving hydroxyurea (OR 3.65; 95% CI 1.601-8.326; p = 0.002) were associated with a higher probability of switching to nilotinib or dasatinib, while receiving a new-generation TKI (OR 0.15; 95% CI 0.071-0.341; p < 0.001) reduced this risk. Conclusions A high proportion of patients needed to change to a second line with nilotinib and dasatinib management. It is necessary to obtain more real world evidence, to improve the effectiveness, adherence and safety of the treatment.

The Role of Mutation Testing in Patients with Chronic Myeloid Leukemia in Chronic Phase after Imatinib Failure and Their Outcomes after Treatment Modification: Single-institutional Experience Over 13 Years

Introduction:

BCR-ABL1 kinase domain mutations represent the most frequent mechanism of resistance to tyrosine kinase inhibitor (TKI) therapy, being detected in 40%–50% of imatinib-resistant patients with chronic myeloid leukemia in chronic phase (CML-CP). Over 100 BCR-ABL1 single-point mutations have been reported in patients with imatinib-resistant CML. There were few studies reported from India on BCR-ABL kinase mutations in imatinib failure patients. We present our data on imatinib resistance mutation analysis (IRMA) and use of imatinib dose hike and 2^nd-generation TKI at our institute.

Materials and Methods:

All patients with a diagnosis of CML in a university hospital from June 2003 to July 2016 and who were tested for IRMA in view of imatinib failure, those in CP, and age <18 years were included in the study.

Results:

A total of 2110 cases of CML reviewed and 269 cases of CML with imatinib failure were analyzed. The male to female ratio was 1.7:1. The median age at presentation was 36 years (range: 18–66 years). Among these, 26% were primary failures and 74% were secondary failures. The treatment was modified either as imatinib dose hike or nilotinib/dasatinib. Molecular response at 12 months was achieved in 25.7% in imatinib dose hike, 46.6% in nilotinib, and 53.8% in dasatinib arms. The 4-year overall survival in mutation detected group was 37.5% and in nonmutated group was 87.7%.

Conclusion:

Imatinib-resistant mutations were more common in the cases with secondary failure though not statistically significant. T315I mutation was the common mutation found in the study. Imatinib dose hike to the failure cases resulted in optimal hematological response rates.

Tyrosine kinase inhibitors in chronic myeloid leukaemia: which, when, for whom?

The therapeutic armamentarium for chronic myeloid leukaemia (CML) comprises mainly tyrosine kinase inhibitors (TKIs), with several agents available for frontline treatment, or for the treatment of disease resistance or intolerance to the first-choice or second-choice drug. The availability of different drugs is a major achievement, but means that choices must be made - which can be difficult and questionable at times. The most important end point considered in decision-making regarding treatment for any cancer is overall survival, but additional factors (such as age, prognostic category, safety, or the possibility of achieving treatment-free remission) should be considered when selecting an agent for frontline treatment. Regardless of the TKI selected for first-line treatment, guidelines that define the importance of reaching specific response indicators and procedures for vigilant follow-up monitoring are established to ensure timely implementation of second-line TKIs. Herein, we discuss the benefits and risks of the different TKIs available for the treatment of patients with CML, and how to decide when to employ these agents at different treatment settings.

Analysis of 2013 European LeukaemiaNet (ELN) responses in chronic phase CML across four frontline TKI modalities and impact on clinical outcomes

This study assessed the relevance of 2013 European LeukaemiaNet (ELN) response categories on patients treated with common frontline tyrosine kinase inhibitors (TKI) in chronic myeloid leukaemia in chronic phase (CML-CP). Four hundred and eighty-seven patients treated with imatinib (400 mg; IM 400, n = 70; 800 mg; IM800, n = 201), dasatinib (n = 107) or nilotinib (n = 109) were analysed. Intention to treat (ITT) analysis indicated that the proportion of patients falling into optimal, warning and failure ELN categories were 89%, 6%, 6% at 3 months, 78%, 17% and 6% at 6 months, and 75%, 13% and 13% at 12 months, respectively. Rates of optimal response at 3 months were 75% for IM400, 90% for IM800, 89% for dasatinib and 97% for nilotinib; 41%, 80%, 86% and 89% at 6 months; and 47%, 77%, 76% and 87% at 12 months, respectively. Patients achieving optimal response had longer eventfree (EFS), failurefree (FFS), transformationfree (TFS) and overall survival (OS) compared to warning and failure responses at all-time points. Treatment with imatinib 800, dasatinib or nilotinib predicted for achieving an optimal response. Optimal response predicted for significantly longer EFS, FFS, TFS and OS at 3, 6 and 12 months, irrespective of the TKI modality used. ELN response categories reliably predicted outcomes in CML patients receiving commonly used TKIs.

Chronic myeloid leukemia: 2016 update on diagnosis, therapy, and monitoring

DISEASE OVERVIEW

Chronic Myeloid Leukemia (CML) is a myeloproliferative neoplasm with an incidence of 1-2 cases per 100,000 adults. It accounts for approximately 15% of newly diagnosed cases of leukemia in adults.

DIAGNOSIS

CML is characterized by a balanced genetic translocation, t(9;22)(q34;q11.2), involving a fusion of the Abelson gene (ABL1) from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11.2. This rearrangement is known as the Philadelphia chromosome. The molecular consequence of this translocation is the generation of a BCR-ABL1 fusion oncogene, which in turn translates into a BCR-ABL oncoprotein. Frontline therapy: Three tyrosine kinase inhibitors (TKIs), imatinib, nilotinib, and dasatinib are approved by the United States Food and Drug Administration for first-line treatment of patients with newly diagnosed CML in chronic phase (CML-CP). Clinical trials with 2nd generation TKIs reported significantly deeper and faster responses; their impact on long-term survival remains to be determined. Salvage therapy: For patients who fail frontline therapy, second-line options include second and third generation TKIs. Although second and third generation TKIs are potent and selective TKIs, they exhibit unique pharmacological profiles and response patterns relative to different patient and disease characteristics, such as patients' comorbidities, disease stage, and BCR-ABL1 mutational status. Patients who develop the T315I "gatekeeper" mutation display resistance to all currently available TKIs except ponatinib. Allogeneic stem cell transplantation remains an important therapeutic option for patients with CML-CP who have failed at least two TKIs, and for all patients in advanced phase disease.

Alectinib Dose Escalation Reinduces Central Nervous System Responses in Patients with Anaplastic Lymphoma Kinase-Positive Non-Small Cell Lung Cancer Relapsing on Standard Dose Alectinib

The central nervous system (CNS) is an important and increasingly recognized site of treatment failure in anaplastic lymphoma kinase (ALK)-positive, non-small cell lung cancer (NSCLC) patients receiving ALK inhibitors. In this report, we describe two ALK-positive patients who experienced initial improvements in CNS metastases on standard dose alectinib (600 mg twice daily), but who subsequently experienced recurrences with symptomatic leptomeningeal metastases. Both patients were dose-escalated to alectinib 900 mg twice daily, resulting in repeat clinical and radiographic responses. Our results suggest that dose intensification of alectinib may be necessary to overcome incomplete ALK inhibition in the CNS and prolong the durability of responses in patients with CNS metastases, particularly those with leptomeningeal carcinomatosis.

Cost-effectiveness analysis of second-line tyrosine kinase inhibitor treatment for chronic myelogenous leukemia

AIM

A cost-effectiveness analysis was performed for sequential treatments of chronic myelogenous leukemia (CML) with tyrosine kinase inhibitors (TKIs) after failure of 1st line imatinib, from a commercial payer perspective in the US.

METHODS

A Markov model was developed to simulate lifetime treatment costs and health outcomes for TKI sequences for treatment of patients resistant or intolerant to 1st-line imatinib. Five health states were included, chronic phase 2nd-line TKI, chronic phase 3rd-line TKI, chronic phase post-TKI, advanced phases, and death. Efficacy (response achievement, loss of response, transformation, death) and safety (adverse events incidence, discontinuation) data are based on clinical trials. Resource utilization, costs, and utilities were based on product labels and publically available data. Uncertainty analyses were conducted for key inputs.

RESULTS

In patients failing imatinib, dasatinib-initiating treatment sequences provide the most survival (ΔLYs = 0.2-2.0), QALYs (ΔQALYs = 0.2-1.9), and accrue highest CML-related costs (ΔCosts = $64,000-$222,000). The average ICER per QALY for dasatinib- vs imatinib-initiating sequences is $100,000 for an imatinib-resistant population. The average ICER per QALY for dasatinib- vs nilotinib-initiating sequences is $170,000 for an imatinib-resistant population, and $160,000 for an imatinib-intolerant population.

CONCLUSIONS

This analysis suggests that dasatinib is associated with increased survival and quality of life compared to high dose imatinib and to a smaller extent with nilotinib, among patients resistant or intolerant to 1st-line imatinib, primarily based on higher cytogenetic response rates observed in clinical studies of dasatinib. Head-to-head studies of sequential use of dasatinib and nilotinib are needed to validate the model findings of improved survival (LYs) with better quality-of-life (QALYs) for patients initiating dasatinib in 2nd-line. However, the model findings (in light of higher cytogenetic response rates with dasatinib) are supported by other studies showing improved quality-of-life for responders, and improved survival for patients achieving cytogenetic response.

Chronic myeloid leukemia: Second-line drugs of choice

The efficacy of second-line treatment for chronic myeloid leukemia (CML) plays an important role in allowing CML patients to enjoy a normal life expectancy. Four tyrosine kinase inhibitors (TKIs) are presently available: bosutinib, dasatinib, nilotinib, ponatinib. Each one has different safety and activity profiles, which are reviewed here. No controlled studies are available to guide treatment decision, which must be based on the characterization of leukemic cells, especially in cases of resistance to TKI, coupled with the safety profile of each TKI. Patient comorbidities also play an important role in the treatment decision, which can achieve a new durable response in over 50% of treated patients.

Detection of BCR/ABL Fusion Gene by Hematological and Cytogenetical Analysis in Chronic Myeloid Leukemia Patients in Quetta, Pakistan

BACKGROUND

Chronic myeloid leukemia (CML) is a myeloproliferative disorder of pluripotent stem cells, caused by reciprocal translocation between the long arms of chromosomes 9 and 22, t(9;22)(q34;q11), known as the Philadelphia chromosome.

MATERIALS AND METHODS

A total of 51 CML patients were recruited in this study. Complete blood counts of all CML patients were performed to find out their total leukocytes, hemoglobin and platelets. FISH was performed for the detection of BCR-ABL fusion and cryptogenic tests using bone marrow samples were performed for the conformation of Ph (9;22)(q34;q11) and variant translocation mechanisms.

RESULTS

In cytogenetic analysis we observed that out of 51 CML patients 40 (88.9%) were Ph positive and 4 (8.88%) had Ph negative chromosomes. Mean values of WBC 134.5 103/μl, hemoglobin 10.44 mg/dl, and platelets 288.6 103/μl were observed in this study.

CONCLUSIONS

In this study, Ph positive translocation between chromosome (9:22)(q34;q11) were observed in 40 (88.9%) CML patients.

Practical issues surrounding the explosion of tyrosine kinase inhibitors for the management of chronic myeloid leukemia

The advent of tyrosine kinase inhibitors (TKIs) has drastically changed the treatment outcome of chronic myeloid leukemia (CML). Imatinib was the first TKI approved, and has been considered the standard of care for more than a decade. Second generation compounds, namely dasatinib and nilotinib, are highly effective in newly diagnosed patients as well as those who fail imatinib. Bosutinib and ponatinib have also become available as second line options. With five agents from which to choose, selecting a TKI has become a challenge. Multiple tests are now available to determine a patient's disease status, making the ideal monitoring strategy unclear. The gold standard for response to TKI therapy remains the achievement of complete cytogenetic response. This review will discuss the practical aspects of selecting a TKI and monitoring a patient once on therapy, including when to consider a treatment change. Other relevant issues, including cost, compliance, role of allogeneic hematopoietic cell transplantation, and discontinuation of TKIs will also be covered.

Imatinib: a breakthrough of targeted therapy in cancer

Deregulated protein tyrosine kinase activity is central to the pathogenesis of human cancers. Targeted therapy in the form of selective tyrosine kinase inhibitors (TKIs) has transformed the approach to management of various cancers and represents a therapeutic breakthrough. Imatinib was one of the first cancer therapies to show the potential for such targeted action. Imatinib, an oral targeted therapy, inhibits tyrosine kinases specifically BCR-ABL, c-KIT, and PDGFRA. Apart from its remarkable success in CML and GIST, Imatinib benefits various other tumors caused by Imatinib-specific abnormalities of PDGFR and c-KIT. Imatinib has also been proven to be effective in steroid-refractory chronic graft-versus-host disease because of its anti-PDGFR action. This paper is a comprehensive review of the role of Imatinib in oncology.

Chronic myeloid leukemia: 2014 update on diagnosis, monitoring, and management

DISEASE OVERVIEW

Chronic Myeloid Leukemia (CML) is a myeloproliferative neoplasm with an incidence of 1-2 cases per 100,000 adults, and accounts for ∼15% of newly diagnosed cases of leukemia in adults.

DIAGNOSIS

CML is characterized by a balanced genetic translocation, t(9;22)(q34;q11.2), involving a fusion of the Abelson oncogene (ABL) from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11.2. This rearrangement is known as the Philadelphia chromosome. The molecular consequence of this translocation is the generation of a BCR-ABL fusion oncogene, which in turn translates into a Bcr-Abl oncoprotein.

FRONTLINE THERAPY

Three tyrosine kinase inhibitors (TKIs), imatinib, nilotinib, and dasatinib have been approved by the US Food and Drug Administration for the first-line treatment of patients with newly diagnosed CML in chronic phase (CML-CP). Clinical trials with second generation TKIs reported significantly deeper and faster responses; their impact on long-term survival remains to be determined.

SALVAGE THERAPY

For patients who fail frontline therapy, second-line options include second and third generation TKIs. Although second and third generation TKIs are potent and specific BCR-ABL TKIs, they exhibit unique pharmacological profiles and response patterns relative to different patient characteristics, such as patients comorbidities, disease stage, and BCR-ABL mutational status. Patients who develop the T315I "gatekeeper" mutation display resistance to all currently available TKIs except ponatinib. Allogeneic transplantation remains an important therapeutic option for CML-CP who have failed at least 2 TKIs, and for all patients in advanced phase disease.

Definition and treatment of resistance to tyrosine kinase inhibitors in chronic myeloid leukemia

Resistance to tyrosine kinase inhibitors (TKIs) has many facets. The causes of resistance include low patient compliance, low plasma or intracellular drug concentration, BCR-ABL1 mutations, and clonal chromosome abnormalities in Ph+ cells, but in at least 50% of patients the causes are currently unknown. Primary resistance occurs when a predefined response level is not achieved within a prespecified period of time. Not achieving a complete hematologic response (CHR) within 3 months, not achieving a partial cytogenetic response and/or a BCR-ABL1 transcripts level ≤10% (international standard) within 6 months, and not achieving a complete cytogenetic response (CCyR) and/or a BCR-ABL1 transcripts level <1% within 12 months, define primary resistance. Secondary resistance is defined by a loss of CHR, or CCyR, or major molecular response. Resistance to imatinib calls without exceptions for a second-generation TKI. In case of resistance to two TKIs, an allogeneic stem cell transplantation should be considered.

Safety and efficacy of switching to nilotinib 400 mg twice daily for patients with chronic myeloid leukemia in chronic phase with suboptimal response or failure on front-line imatinib or nilotinib 300 mg twice daily

In a randomized, phase III trial of nilotinib versus imatinib in patients with newly diagnosed Philadelphia chromosome positive chronic myeloid leukemia in chronic phase, more patients had suboptimal response or treatment failure on front-line imatinib than on nilotinib. Patients with suboptimal response/treatment failure on imatinib 400 mg once or twice daily or nilotinib 300 mg twice daily could enter an extension study to receive nilotinib 400 mg twice daily. After a 19-month median follow up, the safety profile of nilotinib 400 mg twice daily in patients switching from imatinib (n=35) was consistent with previous reports, and few new adverse events occurred in patients escalating from nilotinib 300 mg twice daily (n=19). Of patients previously treated with imatinib or nilotinib 300 mg twice daily, respectively, 15 of 26 (58%) and 2 of 6 (33%) without complete cytogenetic response at extension study entry, and 11 of 34 (32%) and 7 of 18 (39%) without major molecular response at extension study entry, achieved these responses at any time on nilotinib 400 mg twice daily. Estimated 18-month rates of freedom from progression and overall survival after entering the extension study were lower for patients switched from imatinib (85% and 87%, respectively) versus nilotinib 300 mg twice daily (95% and 94%, respectively). Nilotinib dose escalation was generally well tolerated and improved responses in about one-third of patients with suboptimal response/treatment failure. Switch to nilotinib improved responses in some patients with suboptimal response/treatment failure on imatinib, but many did not achieve complete cytogenetic response (clinicaltrials.gov identifiers: 00718263, 00471497 - extension).

Kinase domain mutations and responses to dose escalation in chronic myeloid leukemia resistant to standard dose imatinib mesylate

Imatinib has shown unprecendeted success in the treatment of chronic myeloid leukemia (CML). However, over few years there have been reports regarding the primary and secondary resistance to Imatinib dampening the overall outcome in CML patients. In this study we have tried to assess the effect of dose escalation in patients resistant to standard dose of Imatinib and correlate it with presence of ABL kinase domain (KD) mutations. There were 90 patients resistant to imatinib, out which 29 patients were identified with KD mutations. The most common mutation was T315I , 9 out of 29 patients had it. 35 (38%) responded to dose escalation and had 67% event free survival (EFS) at estimated 2 years. Our results showed that dose escalation can over come resistance in some patients especially those in cytogenetic failure.

BCR-ABL inhibitors: updates in the management of patients with chronic-phase chronic myeloid leukemia

OBJECTIVES

This article reviews recent clinical experiences with first-line and second-line second-generation BCR-ABL inhibitors and discusses considerations for selection of therapy for patients with chronic-phase chronic myeloid leukemia.

METHODS

We reviewed recent publications on PubMed and abstracts from major congresses relevant to the topic.

RESULTS

Therapeutic options for front-line treatment have increased with the approval of two second-generation BCR-ABL inhibitors, dasatinib and nilotinib. Both agents are also treatment options for patients with resistance or intolerance to front-line imatinib. More recently, bosutinib, ponatinib, and omacetaxine have also been approved for patients with resistance or intolerance to prior therapy.

DISCUSSION

Expanded treatment options coupled with rapidly changing treatment guidelines have led to numerous questions regarding the selection and monitoring of therapy. Common concerns include how to best select therapy based upon patient-specific comorbidities, monitoring and interpretation of treatment outcomes, and optimization of dosing when side effects occur.

Targeted therapies in hematology and their impact on patient care: chronic and acute myeloid leukemia

Advances in the genetic and molecular characterizations of leukemias have enhanced our capabilities to develop targeted therapies. The most dramatic example of targeted therapy in cancer to date is the use of targeted BCR-ABL protein tyrosine kinase inhibitors (TKI), which has revolutionized the treatment of chronic myeloid leukemia (CML). Inhibition of the signaling activity of this kinase has proved to be a highly successful treatment target, transforming the prognosis of patients with CML. In contrast, acute myeloid leukemia (AML) is an extremely heterogeneous disease with outcomes that vary widely according to subtype of the disease. Targeted therapy with monoclonal antibodies and small molecule kinase inhibitors are promising strategies to help improve the cure rates in AML. In this review, we will highlight the results of recent clinical trials in which outcomes of CML and AML have been influenced significantly. Also, novel approaches to sequencing and combining available therapies will be covered.

Resistance to tyrosine kinase inhibition therapy for chronic myelogenous leukemia: a clinical perspective and emerging treatment options

The development of tyrosine kinase inhibitors (TKIs) has led to extended lifespans for many patients with chronic myelogenous leukemia (CML). However, 20% to 30% of patients fail to respond, respond suboptimally, or experience disease relapse after treatment with imatinib. A key factor is drug resistance. The molecular mechanisms implicated in this resistance include those that involve upregulation or mutation of BCR-ABL kinase and those that are BCR-ABL independent. The clinical consequences of these molecular mechanisms of resistance for disease pathogenesis remain open for debate. This review summarizes the molecular mechanisms and clinical consequences of TKI resistance and addresses the current and future treatment approaches for patients with TKI-resistant CML.

Study of Imatinib Treatment Patterns and Outcomes Among US Veteran Patients With Philadelphia Chromosome–Positive Chronic Myeloid Leukemia

The authors found that in this population, a substantial number of imatinib-treated patients, including those with disease progression, either discontinued or interrupted imatinib use without switching to other therapies.

Genetic aberrations in imatinib-resistant dermatofibrosarcoma protuberans revealed by whole genome sequencing

Dermatofibrosarcoma protuberans (DFSP) is a very rare soft tissue sarcoma. DFSP often reveals a specific chromosome translocation, t(17;22)(q22;q13), which results in the fusion of collagen 1 alpha 1 (COL1A1) gene and platelet-derived growth factor-B (PDGFB) gene. The COL1A1-PDGFB fusion protein activates the PDGFB receptor and resultant constitutive activation of PDGFR receptor is essential in the pathogenesis of DFSP. Thus, blocking PDGFR receptor activation with imatinib has shown promising activity in the treatment of advanced and metastatic DFSP. Despite the success with targeted agents in cancers, acquired drug resistance eventually occurs. Here, we tried to identify potential drug resistance mechanisms against imatinib in a 46-year old female with DFSP who initially responded well to imatinib but suffered rapid disease progression. We performed whole-genome sequencing of both pre-treatment and post-treatment tumor tissue to identify the mutational events associated with imatinib resistance. No significant copy number alterations, insertion, and deletions were identified during imatinib treatment. Of note, we identified newly emerged 8 non-synonymous somatic mutations of the genes (ACAP2, CARD10, KIAA0556, PAAQR7, PPP1R39, SAFB2, STARD9, and ZFYVE9) in the imatinib-resistant tumor tissue. This study revealed diverse possible candidate mechanisms by which imatinib resistance to PDGFRB inhibition may arise in DFSP, and highlights the usefulness of whole-genome sequencing in identifying drug resistance mechanisms and in pursuing genome-directed, personalized anti-cancer therapy.

Management options for refractory chronic myeloid leukemia: considerations for the elderly

Despite the excellent results obtained with standard-dose imatinib as first-line therapy for chronic myeloid leukemia in the chronic phase, one third of patients do not achieve an optimal response and require alternative therapies due to the emergence of drug resistance. Studies of resistance mechanisms, first tested in vitro and then in vivo, have driven the development of second-generation tyrosine kinase inhibitors (TKIs), dasatinib and nilotinib. These agents have been proven effective in a large number of patients resistant to imatinib and are also effective in older patients. The use of second-generation TKIs in first-line treatment has increased the rate of cytogenetic and molecular responses and reduced the number of patients experiencing disease progression. In this review, we detail the various mechanisms of resistance and management options for refractory patients, in particular in older patients. No differences in terms of efficacy were reported in this subset of patients when treated with nilotinib or dasatinib after imatinib resistance. Results of trials that tested second-generation TKIs as first-line treatment showed similar results in older and younger patients.

Management of imatinib-resistant patients with chronic myeloid leukemia

Since its approval in 2001 for frontline management of chronic myelogenous leukemia (CML), imatinib has proven to be very effective in achieving high remission rates and improving prognosis. However, up to 33% of patients will not achieve optimal response. This has led researchers to develop new second- and third-generation tyrosine kinase inhibitors. In this article, we review the mechanisms of resistance, recommendations for monitoring, assessment of milestones, and management options for patients with CML who are resistant to imatinib therapy. We further explain the potential pitfalls that can lead to unnecessary discontinuation, the prognosis of patients whose condition fails to respond to treatment, and the upcoming therapies.

Chronic myeloid leukemia: 2012 update on diagnosis, monitoring, and management

DISEASE OVERVIEW

Chronic Myeloid Leukemia (CML) is a myeloproliferative neoplasm with an incidence of one-two cases per 100,000 adults and accounts for ∼15% of newly diagnosed cases of leukemia in adults.

DIAGNOSIS

CML is characterized by a balanced genetic translocation, t(9;22)(q34;q11.2), involving a fusion of the Abelson oncogene (ABL) from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11.2. This rearrangement is known as the Philadelphia chromosome. The molecular consequence of this translocation is the generation of a BCR-ABL fusion oncogene, which in turn translates into a Bcr-Abl oncoprotein.

FRONTLINE THERAPY

Three tyrosine kinase inhibitors (TKIs), imatinib, nilotinib, and dasatinib, have been approved by the US Food and Drug Administration for the first-line treatment of patients with newly diagnosed CML in chronic phase (CML-CP). Clinical trials with 2nd generation TKIs reported significantly deeper and faster responses; their impact on long-term survival remains to be determined.

SALVAGE THERAPY

For patients who fail standard-dose imatinib therapy, imatinib dose escalation is a second-line option. Alternative second-line options include 2nd generation TKIs. Although both are potent and specific BCR-ABL TKIs, dasatinib and nilotinib exhibit unique pharmacological profiles and response patterns relative to different patient characteristics, such as disease stage and BCR-ABL mutational status. Patients who develop the T315I "gatekeeper" mutation display resistance to all currently available TKIs and are candidate for clinical trials. Allogeneic transplantation remains an important therapeutic option for CML-CP harboring the T315I mutation, patients who fail 2nd generation TKIs, and for all patients in advanced phase disease.

Advances in treatment of chronic myeloid leukemia with tyrosine kinase inhibitors: the evolving role of Bcr–Abl mutations and mutational analysis

Over the last decade, the treatment of chronic myeloid leukemia has progressed tremendously. The first-generation tyrosine kinase inhibitor imatinib is now flanked by two second-generation molecules, dasatinib and nilotinib – and others are in advanced clinical development. One of the reasons for such intensive research on novel compounds is the problem of resistance, that is thought to be caused, in a proportion of cases, by point mutations in Bcr–Abl. In this article, the authors review how the biological and clinical relevance of Bcr–Abl mutations has evolved in parallel with the availability of more and more therapeutic options. The authors also discuss the practical relevance of Bcr–Abl mutation analysis and how this tool should best be integrated in the optimal clinical management of chronic myeloid leukemia patients.

Clinical trials in chronic myeloid leukemia

The introduction of the tyrosine kinase inhibitor (TKI) imatinib in the treatment of Philadelphia chromosome-positive chronic myeloid leukemia (CML) has substantially improved the outcome of CML patients. Despite the positive results, problems and questions remained. This was the rationale to setup trials for treatment optimization, where imatinib was administered in higher dose and/or in combination with other therapy but where also new and potentially more efficacious second-generation TKI, nilotinib and dasatinib, were investigated. This review summarizes data of recently published first-line studies with the standard treatment imatinib 400 mg as one study arm. Results of randomized comparisons to higher-dose imatinib treatment, nilotinib or dasatinib are discussed. With regard to outcome interpretation, general aspects on statistical issues and endpoint definitions are put into focus. Considering decidedly increased longevity thanks to TKI treatment, future research should include the evaluation of the quality of life (QoL). Relating also to QoL, safe ways of drug discontinuation need to be investigated.

Mechanisms and novel approaches in overriding tyrosine kinase inhibitor resistance in chronic myeloid leukemia

Chronic myeloid leukemia is a stem cell-initiated but progenitor-driven disease induced by the BCR-ABL oncogene. Tyrosine kinase inhibitors (TKIs) were introduced in the late 1990s and have revolutionized the management of chronic myeloid leukemia in chronic phase. The majority of patients can now expect to live a normal life as long as they continue to comply with TKI treatment. However, in a significant proportion of cases TKI resistance develops over time, requiring a switch of therapy. The most frequent mechanism for drug resistance is the development of kinase domain mutations that reduce or completely ablate drug efficacy. Fortunately, the last 10 years have seen an impressive array of new drugs, some modeled on the mechanism of action of imatinib, others employing more novel approaches, for these patients.

TAT-CC fusion protein depresses the oncogenicity of BCR-ABL in vitro and in vivo through interrupting its oligomerization

Chronic myeloid leukemia (CML) is a clonal hematologic malignancy characterized by the BCR-ABL protein. BCR-ABL is a constitutively active tyrosine kinase and plays a critical role in the pathogenesis of CML. Imatinib mesylate, a selective tyrosine kinase inhibitor, is effective in CML, but drug resistance and relapse occur. The coiled-coil (CC) domain located in BCR(1-72) mediates BCR-ABL tetramerization, which is essential for the activation of tyrosine kinase and transformation potential of BCR-ABL. CC domain is supposed to be a therapeutic target for CML. We purified a TAT-CC protein competively binding with the endogenous CC domain to reduce BCR-ABL kinase activity. We found that TAT-CC co-located and interacted with BCR-ABL in Ba/F3-p210 and K562 cells. It induced apoptosis and inhibited proliferation in these cells. It increased the sensitivity of these cells to imatinib and reduced the phosphorylation of BCR-ABL, CRKL and STAT5. We confirmed that TAT-CC could attenuate the oncogenicity of Ba/F3-p210 cells and diminish the volume of K562 solid tumor in mice. We conclude targeting the CC may provide a complementary therapy to inhibit BCR-ABL oncogenicity.

Treatment options for chronic myeloid leukemia

INTRODUCTION

The bcr-abl tyrosine kinase inhibitors (TKIs) are the cornerstone treatment for chronic myeloid leukemia (CML). However, there are many topics related to therapy that remain debated.

AREAS COVERED

The aim of this paper is to give the reader a comprehensive review of how to treat CML at diagnosis, how to monitor the disease and a brief read of special populations and case scenarios. It describes the first-line (imatinib) and second-line (nilotinib and dasatinib) TKIs currently used for the treatment of CML, including landmark studies proving their efficacy, side effect profile, dosage and use in special populations. It also reviews the current guidelines regarding treatment and monitoring of the disease while on TKIs, along with an overview of treatment in advanced stages, the role of allogeneic stem cell transplantation and investigational drugs.

EXPERT OPINION

Although imatinib represented a mayor therapeutic advancement over conventional chemotherapy, second-generation TKIs offer higher rates of optimal response and should be used as the frontline therapy. Patients with the T315I mutation carry a worse prognosis and should be offered allogeneic stem cell transplantation. The treatment in advanced stages of CML remains suboptimal and bench, translational and clinical research is encouraged.

Plasma exposure of imatinib and its correlation with clinical response in the Tyrosine Kinase Inhibitor Optimization and Selectivity Trial

BACKGROUND

This study evaluates the correlation between imatinib trough plasma concentrations (C(min)) and clinical response and safety in patients with newly diagnosed Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase in the Tyrosine Kinase Inhibitor OPtimization and Selectivity (TOPS) trial.

DESIGN AND METHODS

Patients were randomized 1:2 to 400 mg/day or 800 mg/day imatinib. Imatinib C(min) levels were collected at pre-dose before treatment, and at the end of months 1 (day 29), 6, 9, and 12.

RESULTS

Imatinib C(min) were stable over time in the 400 mg/day dose arm, but showed a slight decrease in the 800 mg/day arm due to dose adjustments between months 1-6. The overall median imatinib C(min) levels were 1040, 1200, 1935, and 2690 ng/mL for the actual 300, 400, 600, and 800 mg/day doses, respectively. The rates of major molecular response (MMR) at 3, 6, 9, and 12 months, and complete cytogenetic response (CCyR) at 6 and 12 months were significantly lower among patients with the lowest imatinib C(min) levels at Day 29 (<1165 ng/mL, 25th percentile). There was an apparent association between high imatinib C(min) and the occurrence of grade 3/4 neutropenia and all-grade rash, diarrhea, arthralgia/myalgia, and all-cause edema. Conclusions Imatinib C(min) levels were relatively stable over time and proportional to the dose administered. Patients with an imatinib C(min) above 1165 ng/mL on Day 29 achieved MMR faster and had higher MMR and CCyR rates at 12 months. There appeared to be an association between imatinib C(min) and the frequency of some adverse events. This trial was registered at http://www.clinicaltrials.gov as NCT00124748.

How I treat childhood CML

Chronic myeloid leukemia (CML) is composed of 3% of pediatric leukemias, making evidence-based recommendations difficult. Imatinib has revolutionized the treatment for adult CML by eliminating allogeneic stem cell transplantation for almost all patients in chronic phase. Shown effective in pediatric CML, imatinib and successive tyrosine kinase inhibitors (TKI) have provided more therapeutic options. Because stem cell transplantation has been better tolerated in children and adolescents, the decision to treat by either TKI or transplantation is controversial. We present a recent case of a 12-month-old boy diagnosed with BCR-ABL(+) CML to highlight the controversies in treatment recommendations. We review the pediatric stem cell transplantation outcomes as well as the pediatric experience with imatinib and other TKIs. Finally, we compare the side effects as well as costs associated with allogeneic stem cell transplantation versus TKI therapy. We recommend that frontline therapy for pediatric CML in chronic phase is TKI therapy without transplantation. Patients in accelerated or blast crisis or who fail to reach landmarks on TKIs either because of intolerance or resistance should pursue stem cell transplantation. Although we recommend adopting adult clinical experience to guide therapeutic decision making, the issues of infant CML, drug formulation, pharmacokinetics, and adolescent compliance merit clinical investigation.