Treatment with dasatinib or nilotinib in chronic myeloid leukemia patients who failed to respond to two previously administered tyrosine kinase inhibitors--a single center experience

Therapeutic options for chronic myeloid leukemia following the failure of second-generation tyrosine kinase inhibitor therapy

The management of chronic myeloid leukemia in the chronic phase (CML-CP) has witnessed significant advancements since the identification of a common chromosomal translocation anomaly involving chromosomes 9 and 22, which results in the formation of the Philadelphia chromosome driven by the BCR-ABL1 fusion protein. This discovery paved the way for the development of tyrosine kinase inhibitors (TKIs) that target the adenosine triphosphate (ATP) binding site of ABL1 through the BCR-ABL-1 fusion protein. Following the approval of Imatinib by the Food and Drug Administration (FDA) as the first TKI for CML treatment in 2001, the median overall survival (OS) for chronic phase CML (CML-CP) has significantly improved, approaching that of the general population. However, achieving this milestone crucially depends on reaching certain treatment response milestones. Since the introduction of imatinib, five additional TKIs have been approved for CML-CP treatment. Despite the availability of these treatments, many patients may experience treatment failure and require multiple lines of therapy due to factors such as the emergence of resistance, such as mutations in the ATP binding site of ABL, or intolerance to therapy. This review will primarily focus on exploring treatment options for patients who fail second-generation TKI therapy due to true resistance.

Therapy for patients with chronic phase-chronic myeloid leukemia previously treated with ⩾2 tyrosine kinase inhibitors: a systematic literature review

Background

ATP-competitive tyrosine kinase inhibitors (TKIs) are the current standard of care for patients with chronic phase-chronic myeloid leukemia (CP-CML) in the first-line and second-line (2 L) setting. Treatment after 2 L is not clearly established.

Objective

The objective of this study was to summarize the available evidence to compare the efficacy and safety of interventions in the treatment of CP-CML patients who had received ⩾2 prior TKIs.

Design

A systematic literature review was performed.

Data source and methods

A systematic literature review (SLR) of studies published until May 2021, reporting clinical outcomes in adult patients with CP-CML who had received ⩾ 2 prior TKIs was performed. Studies were identified through the database searches via Ovid platform (Embase, MEDLINE Epub Ahead of Print, In-Process and Other Non-Indexed Citations, and Cochrane Central Register of Controlled Trials), the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP), bibliographic search of relevant reviews, and proceedings from the previous 3 years of the key conferences in the field of oncology.

Results

Our search identified 38 relevant studies. Among the identified studies of the current third-line treatments, the major molecular response (MMR) rate for ponatinib was 19.0-66.7%, 23.3-25.5% for asciminib, 19.2% for omacetaxine, and 13.2% for bosutinib at 6 months. The complete cytogenetic response (CCyR) rate was 21.4-64.8% for ponatinib, 38.7-40.8% for asciminib, 18-24.2% for bosutinib, and 16.1% for omacetaxine at 6 months.

Conclusion

The findings from current SLR demonstrated the lack of data for patients with CML treated with ⩾2 TKIs. TKIs such as asciminib, ponatinib, and bosutinib are valid options for those patients. Further research is needed to identify the best treatment option for patients with CML receiving later lines of therapy.

Matching-adjusted indirect comparison of asciminib versus other treatments in chronic-phase chronic myeloid leukemia after failure of two prior tyrosine kinase inhibitors

PURPOSE

The current standard of care for chronic-phase chronic myeloid leukemia (CP-CML) is tyrosine kinase inhibitors (TKIs). Treatment recommendations are unclear for CP-CML failing ≥ 2 lines of treatment, partly due to the paucity of head-to-head trials evaluating TKIs. Thus, matching-adjusted indirect comparisons (MAICs) were conducted to compare asciminib with competing TKIs in third- or later line (≥ 3L) CP-CML.

METHODS

Individual patient-level data for asciminib (ASCEMBL; follow-up: ≥ 48 weeks) and published aggregate data for comparator TKIs (ponatinib, nilotinib, and dasatinib) informed the analyses. Major molecular response (MMR), complete cytogenetic response (CCyR), and time to treatment discontinuation (TTD) were assessed, where feasible.

RESULTS

Asciminib was associated with statistically significant improvements in MMR by 6 (relative risk [RR]: 1.55; 95% confidence interval [CI]: 1.02, 2.36) and 12 months (RR: 1.48; 95% CI: 1.03, 2.14) vs ponatinib. For CCyR, the results vs ponatinib were similar by 6 (RR: 1.11; 95% CI: 0.81, 1.52) and 12 months (RR: 0.97; 95% CI: 0.73, 1.28). Asciminib was associated with improvements in MMR by 6 months vs dasatinib but with a CI overlapping one (RR 1.52; 95% CI: 0.66, 3.53). Asciminib was associated with statistically significant improvements in CCyR by 6 (RR: 3.57; 95% CI: 1.42, 8.98) and 12 months (RR: 2.03; 95% CI: 1.12, 3.67) vs nilotinib/dasatinib. Median TTD was unreached for asciminib in ASCEMBL. However, post-adjustment asciminib implied prolonged TTD vs nilotinib and dasatinib, but not vs ponatinib.

CONCLUSION

These analyses demonstrate favorable outcomes with asciminib versus competing TKIs, highlighting its therapeutic potential in ≥ 3L CP-CML.

Asciminib monotherapy in patients with CML-CP without BCR::ABL1 T315I mutations treated with at least two prior TKIs: 4-year phase 1 safety and efficacy results

Asciminib is approved for patients with Philadelphia chromosome-positive chronic-phase chronic myeloid leukemia (CML-CP) who received ≥2 prior tyrosine kinase inhibitors or have the T315I mutation. We report updated results of a phase 1, open-label, nonrandomized trial (NCT02081378) assessing the safety, tolerability, and antileukemic activity of asciminib monotherapy 10-200 mg once or twice daily in 115 patients with CML-CP without T315I (data cutoff: January 6, 2021). After ≈4-year median exposure, 69.6% of patients remained on asciminib. The most common grade ≥3 adverse events (AEs) included increased pancreatic enzymes (22.6%), thrombocytopenia (13.9%), hypertension (13.0%), and neutropenia (12.2%); all-grade AEs (mostly grade 1/2) included musculoskeletal pain (59.1%), upper respiratory tract infection (41.7%), and fatigue (40.9%). Clinical pancreatitis and arterial occlusive events (AOEs) occurred in 7.0% and 8.7%, respectively. Most AEs occurred during year 1; the subsequent likelihood of new events, including AOEs, was low. By data cutoff, among patients without the indicated response at baseline, 61.3% achieved BCR::ABL1 ≤ 1%, 61.6% achieved ≤0.1% (major molecular response [MMR]), and 33.7% achieved ≤0.01% on the International Scale. MMR was maintained in 48/53 patients who achieved it and 19/20 who were in MMR at screening, supporting the long-term safety and efficacy of asciminib in this population.

Long-term outcomes of third-line therapy with tyrosine kinase inhibitors in chronic phase chronic myeloid leukemia: A real-life experience

Introduction

Tyrosine kinase inhibitor (TKI) therapy has greatly improved the prognosis of patients with chronic myeloid leukemia (CML), improving the survival expectancy of patients with chronic phase (CP) CML to that of the general population. However, despite these advances, nearly 50% of patients with CP CML experience failure to respond to frontline therapy, and most fail to respond to the subsequent second-line TKI. Treatment guidelines for patients failing second-line therapy are lacking. This study aimed to determine the efficacy of TKIs as third-line therapy in a “real-world” clinical practice setting and identify factors favorably influencing the long-term outcomes of therapy.

Methods

We have retrospectively analyzed the medical records of 100 patients with CP CML.

Results

The median age of the patients was 51 (range, 21–88) years, and 36% of the patients were men. The median duration of the third-line TKI therapy was 22 (range, 1– 147) months. Overall, the rate of achieving complete cytogenetic response (CCyR) was 35%. Among the four patient groups with different levels of responses at baseline, the best results were achieved in the groups with any CyR at the baseline of third-line therapy. Thus, СCyR was reached in all 15 and 8/ 16 (50%) patients with partial cytogenetic response (PCyR) or minimal or minor CyR (mmCyR), respectively, whereas CCyR was detected only in 12/69 (17%) patients without any CyR at baseline (p < 0.001). Univariate regression analysis revealed that the factors negatively associated with CCyR achievement in thirdline TKI therapy were the absence of any CyR on first- or second-line TKI therapy (p < 0.001), absence of CHR prior to third-line TKI (p = 0.003), and absence of any CyR prior to third-line TKI (p < 0.001). During the median observation time from treatment initiation to the last visit [56 (4–180) months], 27% of cases progressed into accelerated phase or blast phase CML, and 32% of patients died.

Discussion

Progression-free survival (PFS) and overall survival (OS) were significantly higher in patients with CCyR on third-line than in the group without CCyR on third-line therapy. At the last visit, third-line TKI therapy was ongoing in 18% of patients, with a median time of treatment exposure of 58 (range, 6–140) months; 83% of these patients had stable and durable CCyR, suggesting that patients without CHR at baseline and without CCyR at least by 12 months on third-line TKI should be candidates for allogeneic stem cell transplantation, third-generation TKIs, or experimental therapies.

From bench to bedside: bridging the gaps in best practices for real-world chronic myeloid leukemia care

INTRODUCTION

Although tyrosine kinase inhibitors (TKIs) determined an improvement of responses and overall survival (OS) in chronic phase chronic myeloid leukemia (CP-CML) patients, some patients still fail the achievement of important milestones.

AREAS COVERED

In this review, we focus on the need of appropriate molecular and mutational monitoring during TKI treatment with new laboratory tools and on new compounds developed to counteract the unmet clinical need in CP-CML.

EXPERT OPINION

The appropriate identification of BCR::ABL1 dependent and independent mechanisms of resistance with Next Generation Sequencing (NGS) and digital droplet PCR (ddPCR) can allow to improve the therapeutic strategies and prevent the onset of a failure to treatment. New compounds have been recently approved or are still in investigational trials to improve the response in some critical forms of resistance and/or intolerance to available TKIs.

Chronic Myeloid Leukemia: Part II-Cost of Care Among Patients in Advanced Phases or Later Lines of Therapy in Chronic Phase in the United States from a Commercial Perspective

Background: Tyrosine kinase inhibitors (TKIs) are the standard-of-care treatment for chronic myeloid leukemia in chronic phase (CML-CP). Despite advances in therapy, there remains a proportion of patients with CML-CP that are refractory/intolerant to TKIs, and these patients cycle through multiple lines of therapy. Moreover, even with TKIs, some patients progress to accelerated phase/blast crisis (AP/BC), which is associated with particularly poor clinical outcomes. Objectives: To describe real-world treatment patterns, healthcare resource utilization (HRU), and costs of patients with CML-CP reaching later lines of therapy or progressing to AP/BC in the United States. Methods: Adult CML patients from administrative claims data (January 1, 2000-June 30, 2019) were classified by health state: on third-line (CML-CP On Treatment), on fourth or later lines (CML-CP Post-Discontinuation), or progressed to AP/BC (CML-AP/BC). Outcomes were assessed by health state. Results: There were 296 (4620 patient-months), 83 (1644 patient-months), and 949 (25 593 patient-months) patients classified in the CML-CP On Treatment, CML-CP Post-Discontinuation, and CML-AP/BC cohorts, respectively. Second-generation TKIs (nilotinib, dasatinib, and bosutinib) were most commonly used in the CML-CP On Treatment (69.1% of patient-months) and CML-CP Post-Discontinuation cohorts (59.1% of patient-months). Three-month outpatient incidence rates (IRs) were 7.6, 8.3, and 7.0 visits in the CML-CP On Treatment, CML-CP Post-Discontinuation, and CML-AP/BC cohort, respectively, with mean costs of $597 per service. Three-month inpatient IRs were 0.6, 0.7, and 1.4 days in the CML-CP On Treatment, CML-CP Post-Discontinuation, and CML-AP/BC cohort, respectively, with mean costs of $5892 per day. Mean hematopoietic stem cell transplantation cost was $352 333; mean 3-month terminal care cost was $107 013. Discussion: Cost of CML care is substantial among patients with CML reaching third-line, fourth or later lines, or progressing to AP/BC, suggesting that the disease is associated with a significant economic and clinical burden. From third-line to fourth or later lines, HRU was observed to increase, and the incidence of inpatient days was particularly high for those who progressed to AP/BC. Conclusion: In this study, patients with CML cycling through TKIs in later lines of therapy or progressing to AP/BC experienced substantial HRU and costs, suggesting unmet treatment needs.

Ponatinib for the treatment of adult patients with resistant or intolerant Chronic-Phase Chronic Myeloid Leukemia

INTRODUCTION

Patients with chronic myeloid leukemia in chronic phase (CP-CML) who are resistant or intolerant to second-generation tyrosine kinase inhibitors (TKIs) may benefit from treatment with a third-generation TKI, like ponatinib.

AREAS COVERED

In this review, the authors discuss the role of ponatinib, an oral pan-inhibitor of BCR-ABL1, with potent activity in heavily pretreated patients, including T315I mutation. In the long-term follow-up of the PACE trial, 60% of patients with prior TKIs exposure achieved a major cytogenetic response with ponatinib and 40% a major molecular response; 5-year overall survival was 73%. Cardiovascular adverse events represent the major toxicity associated with ponatinib. Adopting a dose-reduction approach appeared to be safe: starting with 45 or 30 mg and decreasing to 15 mg once BCR-ABL1/ABL1≤1% is achieved. In patients who are not candidates for ponatinib therapy, asciminib or other novel TKIs like HQP1351, represent alternative options.

EXPERT OPINION

In patients with CP-CML resistant or intolerant to second-generation TKIs, we favor using a third-generation TKI such as ponatinib. Although we initiate a donor search as soon as a patient fails a second-generation TKI, we still prefer treating patients with ponatinib and will only consider transplantation in the event of no response or disease progression.

Third-line therapy for chronic myeloid leukemia: current status and future directions

Chronic myeloid leukemia (CML) is driven by the BCR-ABL1 fusion protein, formed by a translocation between chromosomes 9 and 22 that creates the Philadelphia chromosome. The BCR-ABL1 fusion protein is an optimal target for tyrosine kinase inhibitors (TKIs) that aim for the adenosine triphosphate (ATP) binding site of ABL1. While these drugs have greatly improved the prognosis for CML, many patients ultimately fail treatment, some requiring multiple lines of TKI therapy. Mutations can occur in the ATP binding site of ABL1, causing resistance by preventing the binding of many of these drugs and leaving patients with limited treatment options. The approved TKIs are also associated with adverse effects that may lead to treatment discontinuation in some patients. Efficacy decreases with each progressive line of therapy; data suggest little clinical benefit of treatment with a third-line (3L), second-generation tyrosine kinase inhibitor (2GTKI) after failure of a first-generation TKI and a 2GTKI. Novel treatment options are needed for the patient population that requires treatment in the 3L setting and beyond. This review highlights the need for clear guidelines and new therapies for patients requiring 3L treatment and beyond.

Current Treatment Options for Chronic Myeloid Leukemia Patients Failing Second-Generation Tyrosine Kinase Inhibitors

Despite the excellent overall survival (OS) of patients with chronic myeloid leukemia (CML), a significant proportion will not achieve optimal response to imatinib or second-generation tyrosine kinase inhibitors (2GTKI). For patients with inadequate response to 2GTKIs, alternative 2GTKIs or ponatinib are widely available treatment options in daily clinical practice. Treatment decisions should be guided by correct identification of the cause of treatment failure and accurate distinction between resistant from intolerant or nonadherence patients. This review aims to provide practical advice on how to select the best treatment option in each clinical scenario.

Expert opinion-management of chronic myeloid leukemia after resistance to second-generation tyrosine kinase inhibitors

Regardless of line of therapy, treatment goals in chronic phase chronic myeloid leukemia (CML) are: avoid progression to accelerated phase or blast crisis CML such that patients achieve a life expectancy comparable with that of the general population; avoid adverse events (AEs); and restore and maintain quality of life. The most important prognostic factor for achieving these goals is response to tyrosine kinase inhibitors (TKIs) at key milestones. For patients failing a TKI, a treatment change is mandatory to limit the risk of progression and death. There is currently no precise guideline for patients that fail a second-generation TKI, and there is a paucity of data to guide clinical decision making in this setting. There is, therefore, an unmet need for practical and actionable guidance on how to manage patients who fail a second-generation TKI. Although the term 'failure' includes patients failing for resistance or intolerance, the focus of this paper is failure of a second-generation TKI because of resistance. CML patients who fail their first second-generation TKI for true resistance need a more potent therapy. In these patients, the key issues to consider are the relative appropriateness of early allogeneic hematopoietic stem cell transplantation or the use of a further TKI. Selection of the next line of treatment after second-generation TKI resistance should be individualized and must be based on patient-specific factors including cytogenetics, mutation profile, comorbidities, age, previous history of AEs with prior TKI therapy, and risk profile for AEs on specific TKIs. This expert opinion paper is not in conflict with existing recommendations, but instead represents an evolution of previous notions, based on new data, insights, and clinical experience. We review the treatment options for patients resistant to second-generation TKI therapy and provide our clinical opinions and guidance on key considerations for treatment decision making.

Trifolium Repens Blocks Proliferation in Chronic Myelogenous Leukemia via the BCR-ABL/STAT5 Pathway

Some species of clover are reported to have beneficial effects in human diseases. However, little is known about the activity of the forage plant Trifolium repens, or white clover, which has been recently found to exert a hepatoprotective action. Scientific interest is increasingly focused on identifying new drugs, especially natural products and their derivatives, to treat human diseases including cancer. We analyzed the anticancer effects of T. repens in several cancer cell lines. The phytochemical components of T. repens were first extracted in a methanol solution and then separated into four fractions by ultra-high-performance liquid chromatography. The effects of the total extract and each fraction on cancer cell proliferation were analyzed by MTT assay and Western blotting. T. repens and, more robustly, its isoflavonoid-rich fraction showed high cytotoxic effects in chronic myelogenous leukemia (CML) K562 cells, with IC₅₀ values of 1.67 and 0.092 mg/mL, respectively. The block of cell growth was associated with a total inhibition of BCR-ABL/STAT5 and activation of the p38 signaling pathways. In contrast, these strongly cytotoxic effects did not occur in normal cells. Our findings suggest that the development of novel compounds derived from phytochemical molecules contained in Trifolium might lead to the identification of new therapeutic agents active against CML.

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).

What happens to intolerant, relapsed or refractory chronic myeloid leukemia patients without access to clinical trials?

Objective

To assess clinical outcomes of intolerant, relapsed or refractory patients who could not be treated with new tyrosine kinase inhibitors or experimental therapies.

Methods

A retrospective cohort of 90 chronic myeloid leukemia patients in all phases of the disease treated with imatinib mesylate as their first TKI therapy, and with dasatinib or nilotinib as the next line of therapy. We evaluated clinical outcomes of these patients, with special focus on the group that needed more than two therapy lines.

Results

Thirty-nine percent of patients were refractory or intolerant to imatinib. An 8-year overall survival rate of the patients who went through three or more lines of treatment was significantly lower, compared to those who were able to maintain imatinib as their first-line therapy (83% and 22%, respectively p < 0.01). Decreased overall survival was associated with advanced-phase disease (p < 0.01), failure to achieve major molecular response in first-line treatment (p < 0.01) and interruption of first-line treatment due to any reason (p = 0.023). Failure in achieving complete cytogenetic response and major molecular response and treatment interruption were associated with the progression to the third-line treatment.

Conclusion

The critical outcome observed in relapsed, intolerant or refractory chronic phase CML patients reflects the unmet need for this group of patients without an alternative therapy, such as new drugs or experimental therapies in clinical trials. Broader access to newer treatment possibilities is a crucial asset to improve survival among CML patients, especially those refractory or intolerant to first-line therapies.

Benefits and risks of ponatinib versus bosutinib following treatment failure of two prior tyrosine kinase inhibitors in patients with chronic phase chronic myeloid leukemia: a matching-adjusted indirect comparison

OBJECTIVE

Comparing the benefit-risk profiles of ponatinib vs. bosutinib in third-line (3L) treatment of chronic phase chronic myeloid leukemia (CP-CML) is challenging because their pivotal trials lacked comparator arms. To characterize the overall benefit-risk profile in 3L CP-CML patients treated with bosutinib vs. ponatinib, a matching-adjusted indirect comparison (MAIC) was performed to compare efficacy outcomes and treatment duration after adjusting for trial subjects' baseline characteristics, and tolerability was assessed with an unadjusted comparison of study-drug discontinuation.

METHODS

The MAIC was performed using published data from the pivotal bosutinib trial and the most recent individual-patient-level data on file from the pivotal ponatinib trial.

RESULTS

Responses were more frequent and durable with ponatinib (n = 70 MAIC-adjusted) than with bosutinib (n = 119) - complete cytogenetic response (CCyR): 61% vs. 26%; Kaplan-Meier estimate of maintaining CCyR at 4 years: 89% vs. 54%. Median treatment duration was longer with ponatinib than with bosutinib: 38.4 vs. 8.6 months. Only 9% of ponatinib patients (n = 97 unadjusted) vs. 42% of bosutinib patients discontinued due to death, disease progression or unsatisfactory response; 19% vs. 24% discontinued due to adverse events.

CONCLUSIONS

Based on these surrogate measures of patient benefit-risk profiles, ponatinib appears to provide a net overall benefit vs. bosutinib in 3L CP-CML.