Long-term outcome of chronic myeloid leukemia patients treated frontline with imatinib

Influence of genetic polymorphisms on imatinib concentration and therapeutic response in patients with chronic-phase chronic myeloid leukemia

BACKGROUND

Diminished bioavailability of imatinib in leukemic cells contributes to poor clinical response. We examined the impact of genetic polymorphisms of imatinib on the pharmacokinetics and clinical response in 190 patients with chronic myeloid leukaemia (CML).

METHODS

Single nucleotide polymorphisms were genotyped using pyrophosphate sequencing. Plasma trough levels of imatinib were measured using liquid chromatography-tandem mass spectrometry.

RESULTS

Patients carrying the TT genotype for ABCB1 (rs1045642, rs2032582, and rs1128503), GG genotype for CYP3A5-rs776746 and AA genotype for ABCG2-rs2231142 polymorphisms showed higher concentration of imatinib. Patients with T allele for ABCB1 (rs1045642, rs2032582, and rs1128503), A allele for ABCG2-rs2231142, and G allele for CYP3A5-rs776746 polymorphisms showed better cytogenetic response and molecular response. In multivariate analysis, carriers of the CYP3A5-rs776746 G allele exhibited higher rates of complete cytogenetic response (CCyR) and major molecular response (MMR). Similarly, patients with the T allele of ABCB1-rs1045642 and rs1128503 demonstrated significantly increased CCyR rates. Patients with the A allele of ABCG2-rs2231142 were associated with higher MMR rates. The AA genotype for CYP3A5-rs776746, and the CC genotype for ABCB1-rs104562, and rs1128503 polymorphisms were associated with a higher risk of imatinib failure. Patients with the G allele for CYP3A5-rs776746 exhibited a higher incidence of anemia, and T allele for ABCB1-rs2032582 demonstrated an increased incidence of diarrhea.

CONCLUSIONS

Genotyping of ABCB1, ABCG2, and CYP3A5 genes may be considered in the management of patients with CML to tailor therapy and optimize clinical outcomes.

Asciminib monotherapy in patients with chronic-phase chronic myeloid leukemia with the T315I mutation after ≥1 prior tyrosine kinase inhibitor: 2-year follow-up results

Asciminib targets the BCR::ABL1 myristoyl pocket, maintaining activity against BCR::ABL1T315I, which is resistant to most approved adenosine triphosphate-competitive tyrosine kinase inhibitors. We report updated phase I results (NCT02081378) assessing safety/tolerability and antileukemic activity of asciminib monotherapy 200 mg twice daily in 48 heavily pretreated patients with T315I-mutated chronic-phase chronic myeloid leukemia (CML-CP; data cutoff: January 6, 2021). With 2 years' median exposure, 56.3% of patients continued receiving asciminib. Overall, 62.2% of evaluable patients achieved BCR::ABL1 ≤1% on the International Scale (IS); 47.6% and 81.3% of ponatinib-pretreated and -naive patients, respectively, achieved BCR::ABL1IS ≤1%. Of 45 evaluable patients, 48.9% achieved a major molecular response (MMR, BCR::ABL1IS ≤0.1%), including 34.6% and 68.4% of ponatinib-pretreated and -naive patients, respectively. MMR was maintained until data cutoff in 19 of 22 patients who achieved it. The most common grade ≥3 adverse events (AEs) included increased lipase level (18.8%) and thrombocytopenia (14.6%). Five (10.4%) patients experienced AEs leading to discontinuation, including 2 who discontinued asciminib and died due to COVID-19; these were the only deaths reported. These results show asciminib's effectiveness, including in almost 50% of ponatinib pretreated patients, and confirm its risk-benefit profile, supporting its use as a treatment option for T315I-mutated CML-CP.

Drug resistance mechanisms and treatment strategies mediated by Ubiquitin-Specific Proteases (USPs) in cancers: new directions and therapeutic options

Drug resistance represents a significant obstacle in cancer treatment, underscoring the need for the discovery of novel therapeutic targets. Ubiquitin-specific proteases (USPs), a subclass of deubiquitinating enzymes, play a pivotal role in protein deubiquitination. As scientific research advances, USPs have been recognized as key regulators of drug resistance across a spectrum of treatment modalities, including chemotherapy, targeted therapy, immunotherapy, and radiotherapy. This comprehensive review examines the complex relationship between USPs and drug resistance mechanisms, focusing on specific treatment strategies and highlighting the influence of USPs on DNA damage repair, apoptosis, characteristics of cancer stem cells, immune evasion, and other crucial biological functions. Additionally, the review highlights the potential clinical significance of USP inhibitors as a means to counter drug resistance in cancer treatment. By inhibiting particular USP, cancer cells can become more susceptible to a variety of anti-cancer drugs. The integration of USP inhibitors with current anti-cancer therapies offers a promising strategy to circumvent drug resistance. Therefore, this review emphasizes the importance of USPs as viable therapeutic targets and offers insight into fruitful directions for future research and drug development. Targeting USPs presents an effective method to combat drug resistance across various cancer types, leading to enhanced treatment strategies and better patient outcomes.

Jak2V617F Reversible Activation Shows Its Essential Requirement in Myeloproliferative Neoplasms

Gain-of-function mutations activating JAK/STAT signaling are seen in the majority of patients with myeloproliferative neoplasms (MPN), most commonly JAK2V617F. Although clinically approved JAK inhibitors improve symptoms and outcomes in MPNs, remissions are rare, and mutant allele burden does not substantively change with chronic therapy. We hypothesized this is due to limitations of current JAK inhibitors to potently and specifically abrogate mutant JAK2 signaling. We therefore developed a conditionally inducible mouse model allowing for sequential activation, and then inactivation, of Jak2V617F from its endogenous locus using a combined Dre-rox/Cre-lox dual-recombinase system. Jak2V617F deletion abrogates MPN features, induces depletion of mutant-specific hematopoietic stem/progenitor cells, and extends overall survival to an extent not observed with pharmacologic JAK inhibition, including when cooccurring with somatic Tet2 loss. Our data suggest JAK2V617F represents the best therapeutic target in MPNs and demonstrate the therapeutic relevance of a dual-recombinase system to assess mutant-specific oncogenic dependencies in vivo.

SIGNIFICANCE

Current JAK inhibitors to treat myeloproliferative neoplasms are ineffective at eradicating mutant cells. We developed an endogenously expressed Jak2V617F dual-recombinase knock-in/knock-out model to investigate Jak2V617F oncogenic reversion in vivo. Jak2V617F deletion abrogates MPN features and depletes disease-sustaining MPN stem cells, suggesting improved Jak2V617F targeting offers the potential for greater therapeutic efficacy. See related commentary by Celik and Challen, p. 701. This article is featured in Selected Articles from This Issue, p. 695.

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.

Asciminib (Scemblix): A third-line treatment option for chronic myeloid leukemia in chronic phase with or without T315I mutation

PURPOSE

To review the pharmacology, efficacy, safety, dosing and administration, and place in therapy of asciminib, an oral tyrosine kinase inhibitor (TKI) used as a third-line treatment option for Philadelphia chromosome-positive chronic myeloid leukemia (CML) in chronic phase.

SUMMARY

CML is a rare cancer caused by a chromosomal translocation that forms a fusion of the BCR and ABL1 genes on chromosomes 22 and 9. Until recently, patients for whom first-line treatment options failed were treated with TKIs that bind to the adenosine triphosphate-binding site on BCR-ABL1. However, because of similar mechanisms of action, there continues to be an unmet need in patients for whom at least 2 TKIs have failed or those with a T315I mutation unable to tolerate ponatinib. In October 2021, the Food and Drug Administration approved asciminib (Scemblix), the first TKI specifically targeting the ABL1 myristoyl pocket (STAMP) via allosteric binding, as a third-line option for patients with chronic-phase (CP)-CML. Asciminib received accelerated approval due to meeting its primary endpoint at week 24, demonstrating a major molecular response rate of 25.5% for patients on asciminib compared to 13.2% for those receiving bosutinib. In addition, patients on asciminib achieved a higher rate of complete cytogenetic response at 40.8% compared to a rate of 24.2% for bosutinib. Clinicians prescribing asciminib should monitor for increased levels of pancreatic enzymes, hypertension, cardiovascular toxicity including ischemic and thromboembolic conditions, and decreased numbers of neutrophils and platelets, as these may require treatment interruption, dose reduction, or treatment discontinuation.

CONCLUSION

Asciminib is a unique targeted TKI that provides clinicians with an additional third-line and beyond treatment option for adults with CP-CML regardless of mutation status as well as a second TKI treatment option for patients harboring a T315I mutation.

The Impact of SKP2 Gene Expression in Chronic Myeloid Leukemia

Introduction: The prognosis of chronic myeloid leukemia (CML) patients has been dramatically improved with the introduction of imatinib (IM), the first tyrosine kinase inhibitor (TKI). TKI resistance is a serious problem in IM-based therapy. The human S-phase kinase-associated protein 2 (SKP2) gene may play an essential role in the genesis and progression of CML. Aim of the study: We try to explore the diagnostic/prognostic impact of SKP2 gene expression to predict treatment response in first-line IM-treated CML patients at an early response stage. Patients and methods: The gene expression and protein levels of SKP2 were determined using quantitative RT-PCR and ELISA in 100 newly diagnosed CML patients and 100 healthy subjects. Results: SKP2 gene expression and SKP2 protein levels were significantly upregulated in CML patients compared to the control group. The receiver operating characteristic (ROC) analysis for the SKP2 gene expression level, which that differentiated the CML patients from the healthy subjects, yielded a sensitivity of 86.0% and a specificity of 82.0%, with an area under the curve (AUC) of 0.958 (p < 0.001). The ROC analysis for the SKP2 gene expression level, which differentiated optimally from the warning/failure responses, yielded a sensitivity of 70.59% and a specificity of 71.21%, with an AUC of 0.815 (p < 0.001). Conclusion: The SKP2 gene could be an additional diagnostic and an independent prognostic marker for predicting treatment responses in first-line IM-treated CML patients at an early time point (3 months).

Questions concerning tyrosine kinase-inhibitor therapy and transplants in chronic phase chronic myeloid leukaemia

In this provocative commentary, we consider several questions posed by the late chronic myeloid leukaemia (CML) expert Prof. Michele Baccarani, which he challenged us to address after his death. He noted only a small proportion of people with chronic phase CML receiving tyrosine kinase-inhibitor (TKI)-therapy are likely to achieve sustained therapy-free remission (TFR) and even fewer are likely to be cured. Persons most likely to fail TKItherapy can be identified at diagnosis or soon after starting TKI-therapy. These persons are likely to need lifetime TKI-therapy with attendant risks of adverse events, cost and psychological consequences. Allogeneic transplants achieve much higher rates of leukaemia-free survival compared with TKI-therapy but are associated with transplant-related adverse events including an almost 20 percent risk of transplant-related deaths within 1 year post-transplant and a compromised quality-of-life because of complications such as chronic graft-versus-host disease. Subject-, disease- and transplant-related co-variates associated with transplant outcomes are known with reasonable accuracy. Not everyone likely to fail TKI-therapy is a transplant candidate. However, in those who candidates are physicians and patients need to weigh benefits and risks of TKI-therapy versus a transplant. We suggest transplants should be more often considered in the metric when counseling people with chronic phase CML unlikely to achieve TFR with TKI-therapy. We question whether we are discounting a possible important therapy intervention; we think so.

A phase 3, open-label, randomized study of asciminib, a STAMP inhibitor, vs bosutinib in CML after 2 or more prior TKIs

Patients with chronic myeloid leukemia in chronic phase (CML-CP) resistant/intolerant to ≥2 tyrosine kinase inhibitors (TKIs) are at high risk of experiencing poor outcomes because of disease biology and inadequate efficacy and/or safety of current therapies. Asciminib, a first-in-class BCR-ABL1 inhibitor Specifically Targeting the ABL Myristoyl Pocket (STAMP), has the potential to overcome resistance/intolerance to approved TKIs. In this phase 3, open-label study, patients with CML-CP previously treated with ≥2 TKIs were randomized (2:1) to receive asciminib 40 mg twice daily vs bosutinib 500 mg once daily. Randomization was stratified by major cytogenetic response (MCyR) status at baseline. The primary objective was to compare the major molecular response (MMR) rate at week 24 for asciminib vs bosutinib. A total of 233 patients were randomized to asciminib (n = 157) or bosutinib (n = 76). Median follow-up was 14.9 months. The MMR rate at week 24 was 25.5% with asciminib and 13.2% with bosutinib. The difference in MMR rate between treatment arms, after adjusting for MCyR at baseline, was 12.2% (95% confidence interval, 2.19-22.30; 2-sided P = .029). Fewer grade ≥3 adverse events (50.6% vs 60.5%) and adverse events leading to treatment discontinuation (5.8% vs 21.1%) occurred with asciminib than with bosutinib. The study showed a superior efficacy of asciminib compared with that of bosutinib, together with a favorable safety profile. These results support the use of asciminib as a new therapy in patients with CML-CP who are resistant/intolerant to ≥2 prior TKIs. This trial was registered at www.clinicaltrials.gov as #NCT03106779.

Statins Enhance the Molecular Response in Chronic Myeloid Leukemia when Combined with Tyrosine Kinase Inhibitors

Simple Summary

Approximately 50–60% of patients with chronic myeloid leukemia (CML) achieve a stable deep molecular response (DMR) after tyrosine kinase inhibitor (TKI) therapy. The achievement of DMR is a prerequisite for treatment-free remission. Repurposing statins is a straightforward strategy for enhancing molecular response in CML treatment. Second-generation TKIs have been reported to exhibit cardiovascular toxicity. Thus, statins have been widely prescribed for patients with CML undergoing second-generation TKI therapy for modifying cardiovascular risk factors, such as hyperlipidemia. Furthermore, the results of this study support the therapeutic benefit of the concomitant use of statins in TKI therapy for patients with CML. Additionally, the potential additive effects of statins and TKIs enhance the DMR rate in patients with CML, rendering these effects clinically relevant in these patients. In particular, this combination is a strong candidate for the achievement of DMR in patients with CML who have not achieved DMR with TKI therapy alone.

Abstract

Previous studies have suggested that statins can be repurposed for cancer treatment. However, the therapeutic efficacy of statins in chronic myeloid leukemia (CML) has not yet been demonstrated. In this study, we retrospectively evaluated the outcomes of 408 CML patients who underwent imatinib therapy. The deep molecular response rates in patients treated with the statin/TKI combination were significantly higher than those in patients treated with TKI alone (p = 0.0016). The statin/TKI combination exerted potent cytotoxic effects against wild-type and ABL1 mutant CML, BaF3, and K562/T315I mutant cells. Furthermore, the statin/TKI combination additively inhibited the colony-forming capacity of murine CML-KLS⁺ cells in vitro. In addition, we examined the additive growth-inhibitory effects of the statin/tyrosine kinase inhibitor (TKI) combination against CML patient-derived CD34⁺ cells. The growth-inhibitory effects of the statin/imatinib combination against CD34⁺/CML primary cells were higher than those against CD34⁺/Norm cells (p = 0.005), suggesting that the combination of rosuvastatin and imatinib exerted growth-inhibitory effects against CML CD34⁺ cells, but not against normal CD34⁺ cells. Furthermore, results from RNA sequencing of control and statin-treated cells suggested that statins inhibited c-Myc-mediated and hematopoietic cell differentiation pathways. Thus, statins can be potentially repurposed to improve treatment outcomes in CML patients when combined with TKI therapy.

Validation of CIP2A as a Biomarker of Subsequent Disease Progression and Treatment Failure in Chronic Myeloid Leukaemia

BACKGROUND

It would be clinically useful to prospectively identify the risk of disease progression in chronic myeloid leukaemia (CML). Overexpression of cancerous inhibitor of protein phosphatase 2A (PP2A) (CIP2A) protein is an adverse prognostic indicator in many cancers.

METHODS

We examined CIP2A protein levels in diagnostic samples from the SPIRIT2 trial in 172 unselected patients, of whom 90 received imatinib and 82 dasatinib as first-line treatment.

RESULTS

High CIP2A levels correlated with inferior progression-free survival (p = 0.04) and with worse freedom from progression (p = 0.03), and these effects were confined to dasatinib recipients. High CIP2A levels were associated with a six-fold higher five-year treatment failure rate than low CIP2A levels (41% vs. 7.5%; p = 0.0002), in both imatinib (45% vs. 11%; p = 0.02) and dasatinib recipients (36% vs. 4%; p = 0.007). Imatinib recipients with low CIP2A levels had a greater risk of treatment failure (p = 0.0008). CIP2A levels were independent of Sokal, Hasford, EUTOS (EUropean Treatment and Outcome Study), or EUTOS long-term survival scores (ELTS) or the presence of major route cytogenetic abnormalities. No association was seen between CIP2A levels and time to molecular response or the levels of the CIP2A-related proteins PP2A, SET, SET binding protein 1 (SETBP1), or AKT.

CONCLUSIONS

These data confirm that high diagnostic CIP2A levels correlate with subsequent disease progression and treatment failure. CIP2A is a simple diagnostic biomarker that may be useful in planning treatment strategies.

Na+/K+-ATPase Revisited: On Its Mechanism of Action, Role in Cancer, and Activity Modulation

Maintenance of Na⁺ and K⁺ gradients across the cell plasma membrane is an essential process for mammalian cell survival. An enzyme responsible for this process, sodium-potassium ATPase (NKA), has been currently extensively studied as a potential anticancer target, especially in lung cancer and glioblastoma. To date, many NKA inhibitors, mainly of natural origin from the family of cardiac steroids (CSs), have been reported and extensively studied. Interestingly, upon CS binding to NKA at nontoxic doses, the role of NKA as a receptor is activated and intracellular signaling is triggered, upon which cancer cell death occurs, which lies in the expression of different NKA isoforms than in healthy cells. Two major CSs, digoxin and digitoxin, originally used for the treatment of cardiac arrhythmias, are also being tested for another indication—cancer. Such drug repositioning has a big advantage in smoother approval processes. Besides this, novel CS derivatives with improved performance are being developed and evaluated in combination therapy. This article deals with the NKA structure, mechanism of action, activity modulation, and its most important inhibitors, some of which could serve not only as a powerful tool to combat cancer, but also help to decipher the so-far poorly understood NKA regulation.

Tyrosine kinase inhibitors in chronic myeloid leukaemia and emergent cardiovascular disease

OBJECTIVES

(1) Describe how the risk of major adverse cardiovascular events (MACE) in individuals with chronic myeloid leukaemia (CML) has evolved; (2) evaluate the risk of MACE associated with the prescription of different CML tyrosine kinase inhibitors (TKI).

METHODS

A population-based retrospective study including all patients (n=4238) diagnosed with CML in Ontario, Canada between 1986 and 2017 and and age-matched and sex-matched individuals who received healthcare but who did not have CML (controls: n=42 380). The cohort was divided into those entering before 2001 vs from 2001 onwards (when TKIs were introduced). We developed competing risks models to compare time-to-event in CML cases versus controls. We adjusted for baseline comorbidities and present subdistribution HRs and 95% CIs. The relationship between TKI use and MACE was assessed by logistic regression.

RESULTS

Before 2001 and from 2001 on, patients with CML had a higher crude incidence of MACE than patients without CML (19.8 vs 15.3 and 20.3 vs 12.6 per 1000 person-years, respectively). After adjustment for cardiovascular risk factors, patients with CML had a lower subdistribution hazard for MACE (0.59, 95% CI 0.46 to 0.76) before 2001; but from 2001, the adjusted subdistribution HR for MACE (1.27, 95% CI 0.96 to 1.43) was similar to age-matched and sex-matched patients. The incidence (9.3 vs 13.8 per 1000 person-years) and subdistribution hazard for cardiovascular death (0.43, 95% CI 0.36 to 0.52) were lower in patients with CML than controls before 2001. From 2001 on, the incidence (6.3 vs 5.4 per 1000 person-years) and subdistribution hazard for cardiovascular death (0.99, 95% CI 0.84 to 1.18) were similar to age-matched and sex-matched patients without CML with a higher risk of cerebrovascular events (8.6 vs 5.6 per 1000 person-years; 1.35, 95% CI 1.00 to 1.83) and peripheral arterial events (6.9 vs 3.0 per 1000 person-years; 1.66 95% CI, 1.15 to 2.39) in patients with CML than patients without CML. Compared with imatinib, there was no difference in the risk of MACE among those prescribed dasatinib (OR 0.67, 95% CI 0.41 to 1.10) or nilotinib (OR 1.22, 95% CI 0.70 to 1.97).

CONCLUSIONS

In a contemporary CML population, the risk of MACE and cardiovascular death is at least as high as among age-matched and sex-matched patients without CML and may be higher for cerebrovascular and peripheral arterial events. No difference in the risk of MACE between imatinib, dasatinib and nilotinib was observed.

Managing chronic myeloid leukemia for treatment-free remission: a proposal from the GIMEMA CML WP

Several papers authored by international experts have proposed recommendations on the management of BCR-ABL1+ chronic myeloid leukemia (CML). Following these recommendations, survival of CML patients has become very close to normal. The next, ambitious, step is to bring as many patients as possible into a condition of treatment-free remission (TFR). The Gruppo Italiano Malattie EMatologiche dell'Adulto (GIMEMA; Italian Group for Hematologic Diseases of the Adult) CML Working Party (WP) has developed a project aimed at selecting the treatment policies that may increase the probability of TFR, taking into account 4 variables: the need for TFR, the tyrosine kinase inhibitors (TKIs), the characteristics of leukemia, and the patient. A Delphi-like method was used to reach a consensus among the representatives of 50 centers of the CML WP. A consensus was reached on the assessment of disease risk (EUTOS Long Term Survival [ELTS] score), on the definition of the most appropriate age boundaries for the choice of first-line treatment, on the choice of the TKI for first-line treatment, and on the definition of the responses that do not require a change of the TKI (BCR-ABL1 ≤10% at 3 months, ≤1% at 6 months, ≤0.1% at 12 months, ≤0.01% at 24 months), and of the responses that require a change of the TKI, when the goal is TFR (BCR-ABL1 >10% at 3 and 6 months, >1% at 12 months, and >0.1% at 24 months). These suggestions may help optimize the treatment strategy for TFR.

Treatment-free remission in chronic myeloid leukemia: the patient perspective and areas of unmet needs

In CML, treatment-free remission (TFR) refers to having a stable deep molecular response without the need for ongoing tyrosine kinase inhibitor treatment. Whilst recommendations exist about the technical management of stopping and re-starting therapy, much is still unknown about the experiences of those considering and undertaking TFR. This study sought to obtain the patient perspective, identify areas of unmet needs and create recommendations for improvements. Fifty-six percent of patients reported fear or anxiety during treatment discontinuation, whereas only 7% of patients were asked if they needed psychological support during this period. Where patients re-initiated treatment; 59% felt scared or anxious, and 56% felt depressed. Twenty-six percent of re-initiated patients received psychological and/or emotional support at this time. Sixty percent of patients experienced withdrawal symptoms whilst discontinuing treatment, however, 40% of patients who experienced withdrawal symptoms reported that they were not fully supported by their doctor in managing all the symptoms. Healthcare professionals should further consider how they monitor the psychological well-being of patients who are discontinuing or re-initiating treatment, and review what support is offered in response to identified concerns. Surveillance of withdrawal symptoms should be a priority during treatment discontinuation, along with how healthcare professionals assist in the management of these.

Cardiotoxicity of the BCR-ABL1 tyrosine kinase inhibitors: Emphasis on ponatinib

The advent of tyrosine kinase inhibitors (TKIs) targeted therapy revolutionized the treatment of chronic myeloid leukemia (CML) patients. However, cardiotoxicity associated with these targeted therapies puts the cancer survivors at higher risk. Ponatinib is a third-generation TKI for the treatment of CML patients having gatekeeper mutation T315I, which is resistant to the first and second generation of TKIs, namely, imatinib, nilotinib, dasatinib, and bosutinib. Multiple unbiased screening from our lab and others have identified ponatinib as most cardiotoxic FDA approved TKI among the entire FDA approved TKI family (total 50+). Indeed, ponatinib is the only treatment option for CML patients with T315I mutation. This review focusses on the cardiovascular risks and mechanism/s associated with CML TKIs with a particular focus on ponatinib cardiotoxicity. We have summarized our recent findings with transgenic zebrafish line harboring BNP luciferase activity to demonstrate the cardiotoxic potential of ponatinib. Additionally, we will review the recent discoveries reported by our and other laboratories that ponatinib primarily exerts its cardiotoxicity via an off-target effect on cardiomyocyte prosurvival signaling pathways, AKT and ERK. Finally, we will shed light on future directions for minimizing the adverse sequelae associated with CML-TKIs.

Ponatinib-induced cardiotoxicity: delineating the signalling mechanisms and potential rescue strategies

AIMS

Tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of chronic myelogenous leukaemia (CML). However, cardiotoxicity of these agents remains a serious concern. The underlying mechanism of these adverse cardiac effects is largely unknown. Delineation of the underlying mechanisms of TKIs associated cardiac dysfunction could guide potential prevention strategies, rescue approaches, and future drug design. This study aimed to determine the cardiotoxic potential of approved CML TKIs, define the associated signalling mechanism and identify potential alternatives.

METHODS AND RESULTS

In this study, we employed a zebrafish transgenic BNP reporter line that expresses luciferase under control of the nppb promoter (nppb:F-Luciferase) to assess the cardiotoxicity of all approved CML TKIs. Our in vivo screen identified ponatinib as the most cardiotoxic agent among the approved CML TKIs. Then using a combination of zebrafish and isolated neonatal rat cardiomyocytes, we delineated the signalling mechanism of ponatinib-induced cardiotoxicity by demonstrating that ponatinib inhibits cardiac prosurvival signalling pathways AKT and extra-cellular-signal-regulated kinase (ERK), and induces cardiomyocyte apoptosis. As a proof of concept, we augmented AKT and ERK signalling by administration of Neuregulin-1β (NRG-1β), and this prevented ponatinib-induced cardiomyocyte apoptosis. We also demonstrate that ponatinib-induced cardiotoxicity is not mediated by inhibition of fibroblast growth factor signalling, a well-known target of ponatinib. Finally, our comparative profiling for the cardiotoxic potential of CML approved TKIs, identified asciminib (ABL001) as a potentially much less cardiotoxic treatment option for CML patients with the T315I mutation.

CONCLUSION

Herein, we used a combination of in vivo and in vitro methods to systematically screen CML TKIs for cardiotoxicity, identify novel molecular mechanisms for TKI cardiotoxicity, and identify less cardiotoxic alternatives.

European LeukemiaNet 2020 recommendations for treating chronic myeloid leukemia

The therapeutic landscape of chronic myeloid leukemia (CML) has profoundly changed over the past 7 years. Most patients with chronic phase (CP) now have a normal life expectancy. Another goal is achieving a stable deep molecular response (DMR) and discontinuing medication for treatment-free remission (TFR). The European LeukemiaNet convened an expert panel to critically evaluate and update the evidence to achieve these goals since its previous recommendations. First-line treatment is a tyrosine kinase inhibitor (TKI; imatinib brand or generic, dasatinib, nilotinib, and bosutinib are available first-line). Generic imatinib is the cost-effective initial treatment in CP. Various contraindications and side-effects of all TKIs should be considered. Patient risk status at diagnosis should be assessed with the new EUTOS long-term survival (ELTS)-score. Monitoring of response should be done by quantitative polymerase chain reaction whenever possible. A change of treatment is recommended when intolerance cannot be ameliorated or when molecular milestones are not reached. Greater than 10% BCR-ABL1 at 3 months indicates treatment failure when confirmed. Allogeneic transplantation continues to be a therapeutic option particularly for advanced phase CML. TKI treatment should be withheld during pregnancy. Treatment discontinuation may be considered in patients with durable DMR with the goal of achieving TFR.

Unraveling survivin expression in chronic myeloid leukemia: Molecular interactions and clinical implications

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by the BCR-ABL oncoprotein, known to drive leukemogenesis by orchestrating multiple signaling pathways ultimately involved in cell survival. Despite successful response rates of CML patients to tyrosine kinase inhibitors (TKIs), resistance eventually arises due to BCR-ABL-dependent and independent mechanisms. Survivin is an inhibitor of apoptosis protein acting in the interface between apoptosis deregulation and cell cycle progression. In CML, high levels of survivin have been associated with late stages of disease and therapy resistance. In this review, we provide an overview of important aspects concerning survivin subcellular localization and expression pattern in CML patients and cell lines. Moreover, we highlight the relevance of molecular networks involving survivin for disease progression and treatment resistance. Finally, we discuss the mechanisms accounting for survivin overexpression, as well as novel therapeutic interventions that have been designed to counteract survivin-associated malignancy in CML.

De-regulated STAT5A/miR-202-5p/USP15/Caspase-6 regulatory axis suppresses CML cell apoptosis and contributes to Imatinib resistance

BACKGROUND

STAT5 plays an important role in the transformation of hematopoietic cells by BCR-ABL. However, the downstream target genes activated by STAT5 in chronic myeloid leukemia (CML) cells remain largely unclear. Here, we investigated the mechanistic functional relationship between STAT5A-regulated microRNA and CML cell apoptosis.

METHODS

The expression of USP15, Caspase-6, STAT5A-regulated miR-202-5p and STAT5A was detected by qRT-PCR and Western blotting in CML cell lines and PBMCs of CML patients. Cell apoptosis was evaluated by flow cytometry. Both gain- and loss-of-function experiments were used to investigate the roles of USP15, miR-202-5p and STAT5A in CML. Luciferase reporter assay detected the effect of miR-202-5p on USP15 expression. Xenograft animal model was used to test the effect of anti-miR-202-5p and pimozide on K562 cell xenograft growth.

RESULTS

USP15 expression was significantly downregulated in CML cell lines and PBMCs of CML patients. Depletion of USP15 increased, whereas overexpression of USP15 reduced the resistance of CML cells to Imatinib. Further, decreased deubiquitinating activity of USP15 by USP15 downregulation led to reduced caspase-6 level, thus attenuating CML cell apoptosis. Mechanistically, miR-202-5p was upregulated in K562G cells and negatively regulated USP15 expression by directly targeting USP15 3'-UTR. Correspondingly, upregulation of miR-202-5p enhanced the resistance of CML cells to Imatinib by inhibiting cell apoptosis. Importantly, STAT5A was upregulated in CML cells and directly activated miR-202-5p transcription by binding to the pre-miR-202 promoter. Pimozide induced CML cell apoptosis and significantly reduced K562 cell xenograft growth in vivo by blocking STAT5A/miR-202-5p/USP15/Caspase-6 regulatory axis.

CONCLUSIONS

we provide the first evidence that de-regulated STAT5A/miR-202-5p/USP15/Caspase-6 regulatory axis suppresses the apoptosis of CML cells, targeting this pathway might be a promising therapeutic approach for the treatment of CML.

CDK4/CDK6 inhibition as a novel strategy to suppress the growth and survival of BCR-ABL1T315I+ clones in TKI-resistant CML

Purpose

Ponatinib is the only approved tyrosine kinase inhibitor (TKI) suppressing BCR-ABL1^T315I-mutated cells in chronic myeloid leukemia (CML). However, due to side effects and resistance, BCR-ABL1^T315I-mutated CML remains a clinical challenge. Hydroxyurea (HU) has been used for cytoreduction in CML for decades. We found that HU suppresses or even eliminates BCR-ABL1^T315I+ sub-clones in heavily pretreated CML patients. Based on this observation, we investigated the effects of HU on TKI-resistant CML cells in vitro.

Methods

Viability, apoptosis and proliferation of drug-exposed primary CML cells and BCR-ABL1+ cell lines were examined by flow cytometry and ³H-thymidine-uptake. Expression of drug targets was analyzed by qPCR and Western blotting.

Findings

HU was more effective in inhibiting the proliferation of leukemic cells harboring BCR-ABL1^T315I or T315I-including compound-mutations compared to cells expressing wildtype BCR-ABL1. Moreover, HU synergized with ponatinib and ABL001 in inducing growth inhibition in CML cells. Furthermore, HU blocked cell cycle progression in leukemic cells, which was accompanied by decreased expression of CDK4 and CDK6. Palbociclib, a more specific CDK4/CDK6-inhibitor, was also found to suppress proliferation in primary CML cells and to synergize with ponatinib in producing growth inhibition in BCR-ABL1^T315I+ cells, suggesting that suppression of CDK4/CDK6 may be a promising concept to overcome BCR-ABL1^T315I-associated TKI resistance.

Interpretation

HU and the CDK4/CDK6-blocker palbociclib inhibit growth of CML clones expressing BCR-ABL1^T315I or complex T315I-including compound-mutations. Clinical studies are required to confirm single drug effects and the efficacy of `ponatinib+HU´ and ´ponatinib+palbociclib´ combinations in advanced CML.

Funding

This project was supported by the Austrian Science Funds (FWF) projects F4701-B20, F4704-B20 and P30625.

Chronic myeloid leukemia: the concepts of resistance and persistence and the relationship with the BCR-ABL1 transcript type

Chronic myeloid leukemia is driven by a hybrid gene, BCR-ABL1, that codes for a leukemogenic tyrosine kinase (TK) protein of 210 KDa (p210^BCR-ABL1). Resistance to TK inhibitor (TKI) therapy occurs in relatively few patients, no more than 10%, while persistence of minimal residual disease during TKI therapy occurs in the great majority of patients. Resistance is a cause of death, persistence is compatible with a fairly normal length and quality of life, but may require lifelong treatment. The causes of resistance are heterogeneous, including the development of other genomic abnormalities or the altered expression of other genes, requiring different treatments. The causes of persistence may not be the same as those of resistance. We hypothesize that the variability in breakpoint position within the Major-breakpoint cluster region (M-bcr), resulting in two different messenger RNAs that may or may not include exon 14 of BCR (e13a2 and e14a2, respectively), and, as a consequence, in two p210^BCR-ABL1 proteins that differ by 25 amino acids, may be a cause of persistence. The hypothesis is based on a critical review of the relationships between the BCR-ABL1 transcript types, the response to TKIs, the outcome of treatment, and the immune response, suggesting that the e14a2 transcript is associated with more and deeper molecular responses, hence with a higher probability of achieving treatment-free remission (TFR). Investigating this putative cause of persistence may help bringing more patients into stable TFR.

Salidroside enhances the anti-cancerous effect of imatinib on human acute monocytic leukemia via the induction of autophagy-related apoptosis through AMPK activation

As the typical tyrosine kinase inhibitor, imatinib has been the first-line antineoplastic agent for both chronic myeloid leukemia and acute lymphoblastic leukemia. However, a large number of patients are still resistant to the benefits of imatinib, and they have a dissatisfactory prognosis. Salidroside, a compound that is extracted from natural plants, has been reported to have an excellent anticancer effect and few side effects. In the present study, we have developed a new combination therapy strategy of salidroside and imatinib for combating the growth of acute lymphoblastic leukemia. As demonstrated by the anti-proliferation assay, salidroside exhibited excellent cytotoxicity against myeloid leukemia cells. Moreover, cells treated by the combination therapy of salidroside and imatinib displayed a clear lower growth rate than cells only treated by imatinib, indicating that salidroside has a positive effect on enhancing the cytotoxicity of imatinib against leukemia cells. Subsequently, the underlying mechanisms were investigated. The results revealed that autophagy marker proteins in leukemia cells, including LC3, p62, and Beclin1, displayed a significant expression change after treating them with salidroside plus imatinib, with the levels of LC3 and Beclin1 dramatically increasing while the expression of p62 was significantly decreased. Moreover, an obvious down-regulation of p-PI3K, p-AKT and p-mTOR expression levels in leukemia cells after treatment with salidroside plus imatinib suggested that the PI3K/mTOR pathway plays an important role in the process of cell apoptosis induced by salidroside or imatinib. Further studies showed that pre-incubating the cells with an autophagy inhibitor dramatically inhibited the ability of imatinib to induce autophagy, but did not inhibit the ability of salidroside. The underlying causes were subsequently explored and the results showed that silencing AMPKα1, the most important regulator of autophagy, dramatically attenuates the ability of salidroside to induce cell apoptosis. These results together indicated that salidroside enhances the cytotoxicity of imatinib on acute monocytic leukemia via the induction of autophagy-related apoptosis through AMPK activation. The unique advantages of combination therapy were further confirmed by in vivo experiments, with the tumor-bearing cells treated with salidroside plus imatinib achieving the best anti-tumor effect.

Generic Imatinib in Chronic Myeloid Leukemia Treatment: Long-Term Follow-up

BACKGROUND

Similar to the application of other generic drugs, the use of generic imatinib in the treatment of chronic myeloid leukemia (CML) leads to significant cost savings, but it also raises issues related to efficacy, safety, and quality. This study assessed the long-term outcome of CML patients after administration of generic imatinib.

PATIENTS AND METHODS

The cohort of 83 patients was divided into 2 groups depending on whether generic imatinib was applied in the front-line setting or after switching from original imatinib. The groups were compared regarding rates of optimal treatment response, adverse events, and survival.

RESULTS

In the first group, at the time of switching, rates of complete cytogenetic response experienced, and major molecular response were 95% and 87.5% of patients in the front-line generic imatinib group and the group that switched from original to generic imatinib, respectively. After 24 months of treatment with generic imatinib, the rates of sustained, lost, and experienced major molecular response were 72.5%, 15%, and 12.5%, respectively. In the group treated with front-line generic imatinib at 6 months, 67.4% experienced complete cytogenetic response, while for major molecular response at 12 and 24 months, it was 58.1% and 69.8%, respectively. Estimated 5-year overall survival in the group treated with front-line generic imatinib was 86.1%, while 10-year overall survival in the group treated with second-line generic imatinib was 93.8%.

CONCLUSION

Results of this study with long-term follow-up are further evidence that generic imatinib is at least noninferior to original imatinib regarding efficacy and survival, both when provided initially and as a subsequent replacement for original imatinib.

Somatic variants in epigenetic modifiers can predict failure of response to imatinib but not to second-generation tyrosine kinase inhibitors

There are no validated molecular biomarkers to identify newly-diagnosed individuals with chronic-phase chronic myeloid leukemia likely to respond poorly to imatinib and who might benefit from first-line treatment with a more potent second-generation tyrosine kinase inhibitor. Our inability to predict these ‘high-risk’ individuals reflects the poorly understood heterogeneity of the disease. To investigate the potential of genetic variants in epigenetic modifiers as biomarkers at diagnosis, we used Ion Torrent next-generation sequencing of 71 candidate genes for predicting response to tyrosine kinase inhibitors and probability of disease progression. A total of 124 subjects with newly-diagnosed chronic-phase chronic myeloid leukemia began with imatinib (n=62) or second-generation tyrosine kinase inhibitors (n=62) and were classified as responders or non-responders based on the BCRABL1 transcript levels within the first year and the European LeukemiaNet criteria for failure. Somatic variants affecting 21 genes (e.g. ASXL1, IKZF1, DNMT3A, CREBBP) were detected in 30% of subjects, most of whom were non-responders (41% non-responders, 18% responders to imatinib, 38% non-responders, 25% responders to second-generation tyrosine kinase inhibitors). The presence of variants predicted the rate of achieving a major molecular response, event-free survival, progression-free survival and chronic myeloid leukemia-related survival in the imatinib but not the second-generation tyrosine kinase inhibitors cohort. Rare germline variants had no prognostic significance irrespective of treatment while some pre-leukemia variants suggest a multi-step development of chronic myeloid leukemia. Our data suggest that identification of somatic variants at diagnosis facilitates stratification into imatinib responders/non-responders, thereby allowing earlier use of second-generation tyrosine kinase inhibitors, which, in turn, may overcome the negative impact of such variants on disease progression.

Monitoring and Analysis of Chinese Chronic Myeloid Leukemia Patients Who Have Stopped Tyrosine Kinase Inhibitor Therapy

Discontinuation of tyrosine kinase inhibitor (TKI) therapy after achieving a persistent deep molecular response (DMR) is an urgently needed treatment goal for chronic myeloid leukemia (CML) patients and has been included in the National Comprehensive Cancer Network (NCCN) guidelines (version 2.2017) for CML. Indeed, various studies have confirmed the feasibility of discontinuing TKI therapy. In this study, we analyzed data from 45 CML patients who had discontinued TKI therapy. Univariate analysis was performed to predict factors that were potentially related to treatment-free remission (TFR) and identify the differences between early relapse and late relapse. Out of the 45 patients, 20 exhibited molecular relapse after a median follow-up of 18 months (range, 1-54 months), and the estimated TFR at 24 months was 40%. The univariate analysis revealed that a high Sokal score and interruptions or dose reductions during TKI treatment were the only baseline factors associated with poor outcomes. Our results indicate that TKI discontinuation could be successfully put into practice in China.

ABCB1 and BMI1 mRNA expression in patients with chronic myeloid leukemia: impact on imatinib efficacy

Background

ATP-binding cassette transporters are important in the mechanism of multidrug resistance. ABCB1 displays a high affinity for imatinib. BMI1 is a polycomb group protein thought to be overexpressed in leukemic cells.

Methods

This study was conducted to investigate the prognostic value of ABCB1 and BMI1 expressions in chronic myeloid leukemia (CML). Expression levels were measured in 81 patients newly diagnosed with CML and 20 healthy controls by real time reverse transcription- PCR.

Results

The ABCB1 expression levels did not differ between patients with CML and controls. Low ABCB1 mRNA levels were observed in patients who achieved an optimal response compared to suboptimal and resistant cases (P=0.005). Non-responders showed the highest ABCB1 levels. ABCB1 expression did not affect the progression-free survival (PFS) of patients. BMI1 expression was higher in patients than that in controls (P=0.001). Patients in advanced phases expressed higher levels of BMI1 than those in the chronic phase (P=0.004). High BMI1 expression was associated with a shorter PFS.

Conclusion

ABCB1 mRNA expression may serve as a predictor of the optimal response to imatinib treatment in patients with CML. BMI1 expression was higher in the accelerated and blastic crisis phases of CML and associated with a shorter PFS.

Diagnostic performance of the molecular BCR-ABL1 monitoring system may impact on inclusion of CML patients in stopping trials

In chronic myeloid leukemia (CML), the duration of deep molecular response (MR) before treatment cessation (MR⁴ or deeper, corresponding to BCR-ABL1 ≤ 0.01% on the International Scale (IS)) is considered as a prognostic factor for treatment free remission in stopping trials. MR level determination is dependent on the sensitivity of the monitoring technique. Here, we compared a newly established TaqMan (TM) and our so far routinely used LightCycler (LC) quantitative reverse transcription (qRT)-PCR systems for their ability to achieve the best possible sensitivity in BCR-ABL1 monitoring. We have comparatively analyzed RNA samples from peripheral blood mononuclear cells of 92 randomly chosen patients with CML resembling major molecular remission (MMR) or better and of 128 CML patients after treatment cessation (EURO-SKI stopping trial). While our LC system utilized ABL1, the TM system is based on GUSB as reference gene. We observed 99% concordance with respect to achievement of MMR. However, we found that 34 of the 92 patients monitored by TM/GUSB were re-classified to the next inferior MR log level, especially when LC/ABL1-based results were borderline to thresholds. Thirteen patients BCR-ABL1 negative in LC/ABL1 became positive after TM/GUSB analysis. In the 128 patients included in the EURO-SKI trial identical molecular findings were achieved for 114 patients. However, 14 patients were re-classified to the next inferior log-level by the TM/GUSB combination. Eight of these patients relapsed after treatment cessation; two of them were re-classified from MR⁴ to MMR and therefore did not meet inclusion criteria anymore. In conclusion, we consider both methods as comparable and interchangeable in terms of achievement of MMR and of longitudinal evaluation of clinical courses. However, in LC/ABL1 negative samples, slightly enhanced TM/GUSB sensitivity may lead to inferior classification of clinical samples in the context of TFR.

Analysis of cause of death: Competing risks or progressive illness-death model?

The analysis of cause of death is increasingly becoming a topic in oncology. It is usually distinguished between disease-related and disease-unrelated death. A frequently used approach is to define death as disease-related when a progression to advanced phases has occurred before, otherwise as disease-unrelated. The data are often analyzed as competing risks, while a progressive illness-death model might in fact describe the situation more precisely. In this study, we investigated under which circumstances this misspecification leads to biased estimations of the state occupation probabilities. We simulated data according to the progressive illness-death model in various settings, analyzed them with a competing risks model and with a progressive illness-death model and compared them to the true state occupation probabilities. Censoring was either added independently of the status or based on the patients' status. The simulations showed that the censoring mechanism was decisive for the bias while neither the progression hazard nor the Markov property was important. Further, we found a slightly increased standard deviation for the competing risk estimator when censoring was independent of the patients' status. For illustration, both methods were applied to two practical examples of chronic myeloid leukemia (CML): one randomized controlled trial and one registry data set. While in the first case both estimators yielded almost identical results, in the latter case, visible differences were found between both methods.

The proportion of different BCR-ABL1 transcript types in chronic myeloid leukemia. An international overview

There are different BCR-ABL1 fusion genes that are translated into proteins that are different from each other, yet all leukemogenic, causing chronic myeloid leukemia (CML) or acute lymphoblastic leukemia. Their frequency has never been systematically investigated. In a series of 45503 newly diagnosed CML patients reported from 45 countries, it was found that the proportion of e13a2 (also known as b2a2) and of e14a2 (also known as b3a2), including the cases co-expressing e14a2 and e13a2, was 37.9% and 62.1%, respectively. The proportion of these two transcripts was correlated with gender, e13a2 being more frequent in males (39.2%) than in females (36.2%), was correlated with age, decreasing from 39.6% in children and adolescents down to 31.6% in patients ≥ 80 years old, and was not constant worldwide. Other, rare transcripts were reported in 666/34561 patients (1.93%). The proportion of rare transcripts was associated with gender (2.27% in females and 1.69% in males) and with age (from 1.79% in children and adolescents up to 3.84% in patients ≥ 80 years old). These data show that the differences in proportion are not by chance. This is important, as the transcript type is a variable that is suspected to be of prognostic importance for response to treatment, outcome of treatment, and rate of treatment-free remission.

Effect of Tyrosin Kinase Inhibitors on NK Cell and ILC3 Development and Function

Tyrosin kinase inhibitors (TKI) sharply improved the prognosis of Chronic Myeloid Leukemia (CML) and of Philadelphia+ Acute Lymphoblastic Leukemia (Ph+ALL) patients. However, TKI are not curative because of the development of resistance and lack of complete molecular remission in the majority of patients. Clinical evidences would support the notion that patient's immune system may play a key role in preventing relapses. In particular, increased proportions of terminally differentiated CD56+CD16+CD57+ NK cells have been reported to be associated with successful Imatinib therapy discontinuation or with a deep molecular response in Dasatinib-treated patients. In view of the potential role of NK cells in immune-response against CML, it is important to study whether any TKI have an effect on the NK cell development and identify possible molecular mechanism(s) by which continuous exposure to in vitro TKI may influence NK cell development and repertoire. To this end, CD34+ hematopoietic stem cells (HSC) were cultured in the absence or in the presence of Imatinib, Nilotinib, or Dasatinib. We show that all compounds exert an inhibitory effect on CD56+ cell recovery. In addition, Dasatinib sharply skewed the repertoire of CD56+ cell population, leading to an impaired recovery of CD56+CD117-CD16+CD94/NKG2A+EOMES+ mature cytotoxic NK cells, while the recovery of CD56+CD117+CD94/NKG2A-RORγt+ IL-22-producing ILC3 was not affected. This effect appears to involve the Dasatinib-mediated inhibition of Src kinases and, indirectly, of STAT5-signaling activation in CD34+ cells during first days of culture. Our studies, reveal a possible mechanism by which Dasatinib may interfere with the proliferation and maturation of fully competent NK cells, i.e., by targeting signaling pathways required for differentiation and survival of NK cells but not of ILC3.

Safety and efficacy of switching from branded to generic imatinib in chronic phase chronic myeloid leukemia patients treated in Italy

The use of generic drugs after patent expiration of their originators is a relative novelty in the treatment of chronic cancer patients in Western countries. In this observational study we analyzed a cohort of 294 Italian chronic phase chronic myeloid leukemia patients treated frontline with branded imatinib (Glivec®) for at least 6 months and then uniformly switched to generic imatinib upon requirement of health authorities in early 2017. Median age at diagnosis was 57 years (range 19-87). Sokal risk was low/intermediate/high in 55%, 32% and 8% of cases, respectively. Median duration of branded imatinib treatment was 7.4 years (range 0.5-16.7). At a median follow-up of 7.5 months after switch to generic imatinib, 17% of patients reported new or worsening side effects, but grade 3-4 non-hematological adverse events were rare. Six patients switched back to branded imatinib, with improvement in the side effect profile, and 4 pts moved to bosutinib or nilotinib for resistance/intolerance. The majority of patients were in major (26%) or deep molecular response (66%) at the time of switch. Molecular responses remained stable, improved or worsened in 61%, 25% and 14% of patients, respectively. We conclude that switch to generic imatinib for patients who have been receiving branded imatinib appears to be effective and safe. Molecular responses may continue to improve over time. Some patients experienced new or worsened side effects but less than 5% of the whole cohort needed to switch back to branded imatinib or move to other treatments. Savings were around 3 million Euros.

Chronic Myeloid Leukemia: Long-Term Outcome Data in the Imatinib Era

Recent reports suggest that in the TKI era, the survival of chronic myeloid leukemia approaches that of general population. The real-world situation may be different. We analyzed patients (≥ 18 years) with chronic phase (CP) CML enrolled over a 7-year period (2002-2008) in an imatinib access program. Event was defined as non-achievement/loss of complete hematological response (CHR), loss of cytogenetic response or progression to accelerated (AP)/blast phase (BC). Progression was defined as development of AP/BC. Any delay of ≥ 1 week in reporting for drug refills was categorized as non-adherence. Of the 443 patients with CP-CML who started imatinib [median age: 36 years (18-70); High risk: 32% (Sokal) and 14% (Hasford/EUTOS)], 162 (37%) had received prior therapy [mostly hydroxyurea (N = 153]. CHR was achieved by 430 (97%). After a median follow up of 109.5 months (3.4-184.3), the EFS, PFS and OS at 10 years was 43%, 75% and 76% respectively. Superior EFS was predicted by low-risk Hasford score and adherence to therapy. Adherence to therapy was the only factor which predicted EFS on multivariate analysis (HR 0.64, 95% CI 0.50-0.83, P = 0.001). Long-term follow up of patients with CP-CML reflects poorer survival than those reported from clinical trials and reflects multiple issues that affect "real-world" patients. The continued drop in EFS, noted during long-term follow up, might take time to impact the PFS and OS due to the chronic nature of the disease. Sustained adherence to therapy is important for optimum long-term outcomes.

Long-term follow-up of de novo chronic phase chronic myelogenous leukemia patients on front-line imatinib

For the last 15years, imatinib mesylate (IM) has represented the gold standard treatment for chronic-phase chronic myelogenous leukemia (CP-CML); however, outcomes in the very long term remain unknown. We retrospectively analyzed the outcome of 418 IM first-line treated CP-CML patients followed in three reference centers over 15years in and outside of clinical trials, which is believed to represent the "real-life" care of such patients. Molecular analyses were standardized over the years. In case of intolerance or resistance or IM cessation and progression, all clinical data were collected and analyzed. After a median follow-up of 83 months (range 1-194), the overall survival (OS) rates were 91% and 82%, the progression-free survival (PFS) rates were 88.5% and 81%, and the event-free survival rates, including switching to another tyrosine kinase inhibitor, were 65% and 51%, respectively, at 5 and 10years. Thirteen patients (3%) entered blast crisis (BC) with a median survival of 2.2years after BC onset. Forty-nine percent of patients were in major molecular response at 1 year. Univariate analysis failed to detect any impact on survival of molecular response at 3 and 6 months. Sokal score had a significant impact on OS and PFS in a Cox model. Age had a significant impact on OS and PFS, mainly due to deaths in elderly patients unrelated to CML. Overall, 21% of patients reached a stable (≥1 year) molecular response 4 (MR4) and 6.5% reached MR4.5. At last follow-up, 63% of patients were still on IM and 19% were in treatment-free remission. We conclude that IM is an excellent therapeutic option providing impressive long-term OS rates.

Imatinib and polypharmacy in very old patients with chronic myeloid leukemia: effects on response rate, toxicity and outcome

Background

About 40% of all patients with chronic myeloid leukemia are currently old or very old. They are effectively treated with imatinib, even though underrepresented in clinical studies. Furthermore, as it happens in the general population, they often receive multiple drugs for associated chronic illnesses. Aim of this study was to assess whether or not in imatinib-treated patients aged >75 years the exposure to polypharmacy (5 drugs or more) had an impact on cytogenetic and molecular response rates, event-free and overall survival, as well as on hematological or extra-hematological toxicity.

Methods

296 patients at 35 Italian hematological institutions were evaluated.

Results

Polypharmacy was reported in 107 patients (36.1%), and drugs more frequently used were antiplatelets, diuretics, proton pump inhibitors, ACE-inhibitors, beta-blockers, calcium channel blockers, angiotensin II receptors blockers, statins, oral hypoglycemic drugs and alpha blockers. Complete cytogenetic response was obtained in 174 patients (58.8%), 78 (26.4%) within 6 month, 63 (21.3%) between 7 and 12 months. Major molecular response was obtained in 153 patients (51.7%), 64 (21.6%) within the 12 month. One hundred and twenty-eight cases (43.2%) of hematological toxicity were recorded, together with 167 cases (56.4%) of extra-hematological toxicity. Comparing patients exposed to polypharmacy to those without, no difference was observed pertaining to the dosage of imatinib, cytogenetic and molecular responses and hematological and extra-hematological toxicity.

Conclusion

Notwithstanding the several interactions reported in the literature between imatinib and some of the medications considered herewith, this fact does not seem to have a clinical impact on response rate and outcome.

[Effect of MDR1 and CYP3A5 gene polymorphisms on outcomes of patients receiving imatinib treatment for chronic myeloid leukemia]

OBJECTIVE

To study the effect of MDR1 and CYP3A5 gene polymorphisms on the outcomes of imatinib treatment in patients with chronic myeloid leukemia (CML).

METHODS

A total of 100 patients with CML treated with imatinib were enrolled in this study, including 50 patients with cytogenetic relapse (study group) and 50 without cytogenetic relapse (control group) during the follow-up for 45 months. For all the patients, single nucleotide polymorphisms (SNPs) of C1236T, C3435T, and G2677T/A loci in the MDR1 gene and A6986G locus in CYP3A5 gene were genotyped and the trough levels of imatinib was measured using LC-MS/MS. The relationship between SNPs of the loci and the risk of cytogenetic relapse were analyzed.

RESULTS

The risk of cytogenetic recurrence was significantly higher in patients with CC genotypes of MDR1-C1236T and MDR1-C3435T than in those with CT + TT genotypes (P < 0.05). The median survival time of the patients with TT genotypes of MDR1-C3435T and MDR1-C1236T was significantly higher than that of patients with CC genotypes and CT genotypes (P < 0.05). The incidences of hematologic toxicity and neutropenia were significantly higher in patients with cytogenetic relapse than in those without cytogenetic relapse (P < 0.05). MDR1-C3435T genotype and imatinib concentration were independent predictors of cytogenetic relapse of CML.

CONCLUSIONS

The risk of cytogenetic relapse of CML was significantly affected by SNPs of C1236T and C3435T loci of MDR1 gene and blood imatinib concentration. MDR1-C3435T genotype can be used as a potential biomarker for predicting cytogenetic relapse in CML patients.

Towards Comprehension of the ABCB1/P-Glycoprotein Role in Chronic Myeloid Leukemia

Abstract: The introduction of imatinib (IM), a BCR-ABL1 tyrosine kinase inhibitor (TKI), has represented a significant advance in the first-line treatment of chronic myeloid leukemia (CML). However, approximately 30% of patients need to discontinue IM due to resistance or intolerance to this drug. Both resistance and intolerance have also been observed in treatment with the second-generation TKIs-dasatinib, nilotinib, and bosutinib-and the third-generation TKI-ponatinib. The mechanisms of resistance to TKIs may be BCR-ABL1-dependent and/or BCR-ABL1-independent. Although the role of efflux pump P-glycoprotein (Pgp), codified by the ABCB1 gene, is unquestionable in drug resistance of many neoplasms, a longstanding question exists about whether Pgp has a firm implication in TKI resistance in the clinical scenario. The goal of this review is to offer an overview of ABCB1/Pgp expression/activity/polymorphisms in CML. Understanding how interactions, associations, or cooperation between Pgp and other molecules-such as inhibitor apoptosis proteins, microRNAs, or microvesicles-impact IM resistance risk may be critical in evaluating the response to TKIs in CML patients. In addition, new non-TKI compounds may be necessary in order to overcome the resistance mediated by Pgp in CML.

Long-Term Side Effects of Tyrosine Kinase Inhibitors in Chronic Myeloid Leukemia

Most patients with chronic myeloid leukemia have deep and durable responses when treated with BCR-ABL1 tyrosine kinase inhibitors (TKIs). Imatinib (the first approved TKI), nilotinib, and dasatinib are used in newly diagnosed, relapsed or intolerant patients, while bosutinib and ponatinib are used only in relapsed or intolerant patients. Previously the drug of choice was related to the likelihood of response and, to a small extent, patient comorbidities. The long-term toxicities, particularly cardiopulmonary side effects, are now impacting treatment choice, making patient comorbidities of significant concern. About 10 % of patients do not tolerate their initial BCR-ABL1 TKI and an increasing number are developing long-term side effects, particularly with the second generation drugs. Side effects of the five drugs reviewed here highlight the differences between cardiovascular, pulmonary, gastrointestinal, and endocrine toxicities, as well as possible second malignancies. There is increasing evidence that patients whose disease is controlled by TKI's will have greater impact on their quality of life from comorbidities or drug adverse events than from the disease itself. Research into management of long-term toxicities is needed.

Frontline Dasatinib Treatment in a "Real-Life" Cohort of Patients Older than 65 Years with Chronic Myeloid Leukemia

Dasatinib (DAS) has been licensed for the frontline treatment in chronic myeloid leukemia (CML). However, very few data are available regarding its efficacy and toxicity in elderly patients with CML outside clinical trials. To address this issue, we set out a “real-life” cohort of 65 chronic phase CML patients older than 65 years (median age 75.1 years) treated frontline with DAS in 26 Italian centers from June 2012 to June 2015, focusing our attention on toxicity and efficacy data. One third of patients (20/65: 30.7%) had 3 or more comorbidities and required concomitant therapies; according to Sokal classification, 3 patients (4.6%) were low risk, 39 (60.0%) intermediate risk, and 20 (30.8%) high risk, whereas 3 (4.6%) were not classifiable. DAS starting dose was 100 mg once a day in 54 patients (83.0%), whereas 11 patients (17.0%) received less than 100 mg/day. Grade 3/4 hematologic and extrahematologic toxicities were reported in 8 (12.3%) and 12 (18.5%) patients, respectively. Overall, 10 patients (15.4%) permanently discontinued DAS because of toxicities. Pleural effusions (all WHO grades) occurred in 12 patients (18.5%) and in 5 of them occurred during the first 3 months. DAS treatment induced in 60/65 patients (92.3%) a complete cytogenetic response and in 50/65 (76.9%) also a major molecular response. These findings show that DAS might play an important role in the frontline treatment of CML patients >65 years old, proving efficacy and having a favorable safety profile also in elderly subjects with comorbidities.

The BCR-ABL1 transcript type influences response and outcome in Philadelphia chromosome-positive chronic myeloid leukemia patients treated frontline with imatinib

The most frequent BCR-ABL1 fusion transcripts in chronic myeloid leukemia (CML) are the e13a2 (b2a2) and the e14a2 (b3a2) ones. In the imatinib era few studies addressing the prognostic significance of the BCR-ABL1 transcript type in early chronic phase CML have been published. Overall, these studies suggest that in e14a2 patients the response to imatinib is faster and deeper. To evaluate if the BCR-ABL1 transcript type (e13a2 compared to e14a2) affect the response to imatinib and the clinical outcome in newly diagnosed adult CML patients, 559 patients enrolled in 3 prospective studies (NCT00514488, NCT00510926, observational study CML/023) were analyzed. A qualitative PCR was performed at baseline: 52% patients had a e14a2 transcript, 37% a e13a2 transcript, 11% co-expressed both transcripts and 1% had other rare transcripts. The median follow-up was 76 months (95% of the patients had at least a 5-year observation). The complete cytogenetic response rates were comparable in e14a2 and e13a2 patients. The median time to MR^3.0 (6 and 12 months) and MR^4.0 (41 and 61 months) was significantly shorter for e14a2 patients compared to e13a2 patients, with a higher cumulative probability of MR^3.0 (88% and 83%, P < .001) and MR^4.0 (67% and 52%, P = .001). The 7-year overall survival (90% and 83%, P = .017), progression-free survival (89% and 81%, P = .005) and failure-free survival (71% and 54%, P < .001) were significantly better in patients with e14a2 transcript. In conclusion, patients with e13a2 transcript had a slower molecular response with inferior response rates to imatinib and a poorer long-term outcome.

ASXL1 and BIM germ line variants predict response and identify CML patients with the greatest risk of imatinib failure

Scoring systems used at diagnosis of chronic myeloid leukemia (CML), such as Sokal risk, provide important response prediction for patients treated with imatinib. However, the sensitivity and specificity of scoring systems could be enhanced for improved identification of patients with the highest risk. We aimed to identify genomic predictive biomarkers of imatinib response at diagnosis to aid selection of first-line therapy. Targeted amplicon sequencing was performed to determine the germ line variant profile in 517 and 79 patients treated with first-line imatinib and nilotinib, respectively. The Sokal score and ASXL1 rs4911231 and BIM rs686952 variants were independent predictors of early molecular response (MR), major MR, deep MRs (MR⁴ and MR^4.5), and failure-free survival (FFS) with imatinib treatment. In contrast, the ASXL1 and BIM variants did not consistently predict MR or FFS with nilotinib treatment. In the imatinib-treated cohort, neither Sokal or the ASXL1 and BIM variants predicted overall survival (OS) or progression to accelerated phase or blast crisis (AP/BC). The Sokal risk score was combined with the ASXL1 and BIM variants in a classification tree model to predict imatinib response. The model distinguished an ultra-high-risk group, representing 10% of patients, that predicted inferior OS (88% vs 97%; P = .041), progression to AP/BC (12% vs 1%; P = .034), FFS (P < .001), and MRs (P < .001). The ultra-high-risk patients may be candidates for more potent or combination first-line therapy. These data suggest that germ line genetic variation contributes to the heterogeneity of response to imatinib and may contribute to a prognostic risk score that allows early optimization of therapy.

Incidence of second primary malignancies and related mortality in patients with imatinib-treated chronic myeloid leukemia

The majority of patients with chronic myeloid leukemia are successfully managed with life-long treatment with tyrosine kinase inhibitors. In patients in chronic phase, other malignancies are among the most common causes of death, raising concerns on the relationship between these deaths and the off-target effects of tyrosine kinase inhibitors. We analyzed the incidence of second primary malignancies, and related mortality, in 514 chronic myeloid leukemia patients enrolled in clinical trials in which imatinib was given as first-line treatment. We then compared the observed incidence and mortality with those expected in the age- and sex-matched Italian general population, calculating standardized incidence and standardized mortality ratios. After a median follow-up of 74 months, 5.8% patients developed second primary malignancies. The median time from chronic myeloid leukemia to diagnosis of the second primary malignancies was 34 months. We did not find a higher incidence of second primary malignancies compared to that in the age- and sex-matched Italian general population, with standardized incidence ratios of 1.06 (95% CI: 0.57–1.54) and 1.61 (95% CI: 0.92–2.31) in males and females, respectively. Overall, 3.1% patients died of second primary malignancies. The death rate in patients with second primary malignancies was 53% (median overall survival: 18 months). Among females, the observed cancer-related mortality was superior to that expected in the age- and sex-matched Italian population, with a standardized mortality ratio of 2.41 (95% CI: 1.26 – 3.56). In conclusion, our analysis of patients with imatinib-treated chronic myeloid leukemia did not reveal a higher incidence of second primary malignancies; however, the outcome of second primary malignancies in such patients was worse than expected. Clinicaltrials.gov: NCT00514488, NCT00510926.