Imatinib for newly diagnosed patients with chronic myeloid leukemia: incidence of sustained responses in an intention-to-treat analysis

What clinicians should know about surrogate end points in hematologic malignancies

ABSTRACT

Use of surrogates as primary end points is commonplace in hematology/oncology clinical trials. As opposed to prognostic markers, surrogates are end points that can be measured early and yet can still capture the full effect of treatment, because it would be captured by the true outcome (eg, overall survival). We discuss the level of evidence of the most commonly used end points in hematology and share recommendations on how to apply and evaluate surrogate end points in research and clinical practice. Based on the statistical literature, this clinician-friendly review intends to build a bridge between clinicians and surrogacy specialists.

A Comprehensive Review of Cancer Drug-Induced Cardiotoxicity in Blood Cancer Patients: Current Perspectives and Therapeutic Strategies

OPINION STATEMENT

Cardiotoxicity has emerged as a serious outcome catalyzed by various therapeutic targets in the field of cancer treatment, which includes chemotherapy, radiation, and targeted therapies. The growing significance of cancer drug-induced cardiotoxicity (CDIC) and radiation-induced cardiotoxicity (CRIC) necessitates immediate attention. This article intricately unveils how cancer treatments cause cardiotoxicity, which is exacerbated by patient-specific risks. In particular, drugs like anthracyclines, alkylating agents, and tyrosine kinase inhibitors pose a risk, along with factors such as hypertension and diabetes. Mechanistic insights into oxidative stress and topoisomerase-II-B inhibition are crucial, while cardiac biomarkers show early damage. Timely intervention and prompt treatment, especially with specific agents like dexrazoxane and beta-blockers, are pivotal in the proactive management of CDIC.

SOHO State of the Art Updates and Next Questions: Oral Therapy in Acute Myeloid Leukemia

With the recent development of several new effective agents, treatment of patients with acute myeloid leukemia (AML) is evolving. Molecularly targeted agents developed against leukemogenic pathways are demonstrating significant promise both as monotherapy and in combination with standard regimens. Although oral chemotherapeutic agents have long been used in the treatment of various malignancies, their use in patients with AML has been hitherto limited. The availability of most newly approved targeted agents in oral formulation has provided us with the potential for developing all oral regimens in AML. This is particularly important for the older, less fit patients allowing reduced requirements for hospital visits in order to administer therapy, especially when in remission and for continuation of therapy. A potential barrier to the success of such regimens is adherence to therapy with prior studies demonstrating increased success of therapy with high adherence. Strategies to develop completely oral regimens are likely to further revolutionize AML therapy especially in the elderly.

CX‑5461 potentiates imatinib‑induced apoptosis in K562 cells by stimulating KIF1B expression

The selective RNA polymerase I inhibitor CX-5461 has been shown to be effective in treating some types of leukemic disorders. Emerging evidence suggests that combined treatments with CX-5461 and other chemotherapeutic agents may achieve enhanced effectiveness as compared with monotherapies. Currently, pharmacodynamic properties of the combination of CX-5461 with tyrosine kinase inhibitors remain to be explored. The present study tested whether CX-5461 could potentiate the effect of imatinib in the human chronic myeloid leukemia cell line K562, which is p53-deficient. It was demonstrated that CX-5461 at 100 nM, which was non-cytotoxic in K562 cells, potentiated the pro-apoptotic effect of imatinib. Mechanistically, the present study identified that the upregulated expression of kinesin family member 1B (KIF1B) gene might be involved in mediating the pro-apoptotic effect of imatinib/CX-5461 combination. Under the present experimental settings, however, neither CX-5461 nor imatinib alone exhibited a significant effect on KIF1B expression. Moreover, using other leukemic cell lines, it was demonstrated that regulation of KIF1B expression by imatinib/CX-5461 was not a ubiquitous phenomenon in leukemic cells and should be studied in a cell type-specific manner. In conclusion, the results suggested that the synergistic interaction between CX-5461 and imatinib may be of potential clinical value for the treatment of tyrosine kinase inhibitor-resistant chronic myeloid leukemia.

The Contemporary Role of Hematopoietic Stem Cell Transplantation in the Management of Chronic Myeloid Leukemia: Is It the Same in All Settings?

Hematopoietic stem cell transplantation (HSCT) for chronic myeloid leukemia (CML) patients has transitioned from the standard of care to a treatment option limited to those with unsatisfactory tyrosine kinase inhibitor (TKI) responses and advanced disease stages. In recent years, the threshold for undergoing HSCT has increased. Most CML patients now have life expectancies comparable to the general population, and therefore, the goal of therapy is shifting toward achieving treatment-free remission (TFR). While TKI discontinuation trials in CML show potential for achieving TFR, relapse risk is high, affirming allogeneic HSCT as the sole curative treatment. HSCT should be incorporated into treatment algorithms from the time of diagnosis and, in some patients, evaluated as soon as possible. In this review, we will look at some of the recent advances in HSCT, as well as its indication in the era of aiming for TFR in the presence of TKIs in CML.

Long-Term Efficacy of High-Dose Imatinib in Hispanic Patients Without Access to Second-Generation Tyrosine Kinase Inhibitors Treated in LATAM Centers

BACKGROUND

While second-generation tyrosine kinase inhibitors (TKI) revolutionized treatment for patients with chronic myeloid leukemia (CML) who developed a suboptimal response to imatinib, many patients in developing countries are fixed to the latter due to socioeconomic barriers. Despite this scenario, scarce information is available to evaluate the clinical prognosis of these patients.

METHODS

We conducted a retrospective cohort analysis to compare the overall mortality of patients with CML who developed a suboptimal response to a standard dose of imatinib and were treated with either high-dose imatinib or a second-generation TKI. We created a marginal structural model with inverse probability weighting and stabilized weights. Our primary outcome was overall survival (OS) at 150 months. Our secondary outcomes were disease-free survival (DFS) at 150 months and adverse events.

RESULTS

The cohort included 148 patients, of which 32 received high-dose imatinib and 116 a second-generation TKI. No difference was found in the 150-month overall survival risk (RR: 95% CI 0.91, 0.55-1.95, P-value = .77; RD: -0.04, -0.3 to 0.21, P-value = .78) and disease-free survival (RR: 1.02, 95% CI 0.53-2.71, P-value = .96; RD: 0.01, -0.26 to 0.22, P-value = .96). There was also no difference in the incidence of adverse events in either group.

CONCLUSION

Ideally, patients who develop a suboptimal response to imatinib should be switched to a second-generation TKI. If impossible, however, our findings suggest that patients treated with high-dose imatinib have a similar overall survival and disease-free survival prognosis to patients receiving a second-generation TKI.

Project Confirm: Accelerated Drug Approvals for Chronic Myeloid Leukemia

The FDA has an accelerated approval program for drugs that have been identified as promising treatments for serious conditions when the available data suggest that the benefits outweigh the foreseeable risks. All of the currently available treatment options for chronic myeloid leukemia (CML) initially went through the accelerated approval program. Here, a group of academic CML experts, patient panelists, and members from the FDA convened to discuss the utility of the accelerated approval program as it pertains to CML, and the utility of this program in future drug development in this disease. The results of that discussion are summarized here.

Chronic myeloid leukemia without major molecular response after 2 years of treatment with tyrosine kinase inhibitor

Achieving major molecular response (MMR) with BCR::ABL1 tyrosine kinase inhibitors (TKIs) is associated with lower chances of progression to advanced phase disease and higher chances of treatment-free remission (TFR) in patients with chronic myeloid leukemia (CML). Failure to achieve this molecular milestone after 1 year has been highlighted as "suboptimal" or "warning" sign of treatment failure in CML guidelines and recommendations and implied to predict a poor long-term outcome. In this analysis, we report the long-term outcome of 131 patients who did not achieve MMR within the first 2 years of TKI therapy. Patients who achieved a major cytogenetic response (MCyR; roughly equivalent to BCR::ABL1 transcript levels on the International Scale [IS] <10%) had good long-term overall survival (OS) (10-year OS of 88%) and CML-related overall survival (CML-OS) (10-year CML-OS of 95%). The achievement of MCyR within the first 2 years of treatment predicted a better OS (HR = 0.43, p = .03). The value of MMR was even less pronounced among patients aged 60 years or older at diagnosis, in whom mortality was primarily due to comorbidities unrelated to CML (10-year OS of 55% vs. 10-year CML-OS of 100%). In conclusion, achievement of MCyR within 2 years is a reasonable milestone in CML, and these patients can still have good outcomes even when MMR is not achieved.

Children with chronic myeloid leukaemia treated with front-line imatinib have a slower molecular response and comparable survival compared with adults: a multicenter experience in Taiwan

BACKGROUND

The direct comparison of molecular responses of front-line imatinib (IM) monitored at the same laboratory between children and adults with chronic phase (CP) of chronic myeloid leukaemia (CML) had not been reported. In this multicenter study, we compared the landmark molecular responses and outcomes of paediatric and adult CML-CP cohorts treated with front-line IM in whom the BCR::ABL1 transcript levels were monitored at the same accredited laboratory in Taiwan.

METHODS

Between June 2004 and July 2020, 55 newly diagnosed paediatric and 782 adult CML-CP patients, with molecular diagnosis and monitoring at the same reference laboratory in Taiwan, were enrolled. The criteria of 2020 European LeukemiaNet were applied to evaluate the molecular responses.

RESULTS

By year 5, the cumulative incidences of IS <1%, MMR, MR4.0 and MR4.5 of paediatric patients were all significantly lower than those of adult patients (58 vs 75%, 48 vs 66%, 25 vs 44%, 16 vs 34%, respectively). The 10-year progression-free survival (PFS) (90%) and overall survival (OS) (94%) of paediatric patients did not differ from those (92%) of adult patients.

CONCLUSIONS

We demonstrated the paediatric cohort had slower molecular responses to front-line IM and similar outcomes in 10-year PFS and OS in real-world practice.

Investigating the Activity of Indole-2-on Derivative Src Kinase Inhibitors Against Chronic Myeloid Leukemia Cells

BACKGROUND

Src family tyrosine kinases play a potential role in Bcr-Abl-induced leukemogenesis. Src kinase inhibitors are reported as selective inhibitors of chronic myeloid leukemia.

OBJECTIVE

Since Src kinase inhibitors have an inhibitive effect on chronic myeloid leukemia, indole derivatives (C-1, C-2, C-3) previously found as potent inhibitors of Src kinase were tested against chronic myeloid leukemia in this study.

METHODS

Cell viability of K562 and R/K562 cells, antiproliferative and antioxidant effects, and inhibition profiles of Bcr-Abl kinase of indole derivatives were determined compared to dasatinib and imatinib.

RESULTS

The results showed that compounds affected cell proliferation and decreased the levels of Bcr/Abl. These results confirmed that the antileukemic activity of compounds was related to Bcr/Abl expression. Docking studies also presented that compounds are inhibitors of both Src and Abl kinases. Calculation of drug-like properties showed that compounds could be potential drug candidates.

CONCLUSION

Among indole-2-on derivatives, previously identified as Src kinase inhibitors, C-2 has been discovered to be a strong anticancer drug that is active against susceptible and resistant K562 cell lines and induces apoptosis.

Imatinib plasma levels in patients with chronic myeloid leukaemia under routine clinical practice conditions

INTRODUCTION

The addition of imatinib to the therapeutic arsenal for chronic myeloid leukaemia (CML) has changed the natural course of the disease, in such a way that it is now considered a chronic pathology. However, to achieve therapeutic success, it is necessary to reach adequate plasma concentrations to ensure efficacy and safety.In this study, we aimed to evaluate the plasma concentration of imatinib, analysing its influence on effectiveness and safety in patients with CML.

METHODS

We performed a descriptive, multicentre study in which imatinib plasma levels from patients diagnosed with CML between 2019-2020 were analysed. An optimal therapeutic range of 750-1500 ng/mL was established for the stratification of patients, according to their minimum plasma concentrations measured at steady state (Cssmin).

RESULTS

A total of 28 patients were included, of whom only 39.3% (n = 11) showed Cssmin within the therapeutic range. 100% of patients with Cssmin >750 ng/mL achieved an optimal molecular response, while only 50% of patients with Cssmin <750 ng/mL achieved an optimal molecular response (p = 0.0004). The toxicity rate was 36.4% for patients with Cssmin >1500 ng/mL and 5.9% for those with Cssmin <1500 ng/mL (p = 0.039).

CONCLUSIONS

This study aimed to describe the correlation between the toxicity and effectiveness of imatinib according to its Cssmin in routine clinical practice conditions. Based on our findings, it would be certainly justified to monitor patient plasma concentrations of imatinib on a daily routine basis in our hospitals.

BCR/ABL1ΔE7-8-9 isoform contributes to tyrosine kinase inhibitor resistance in chronic myeloid leukemia

In chronic myeloid leukemia (CML) patients, the involvement of the BCR/ABL1 isoform in tyrosine kinase inhibitors (TKIs) resistance has attracted lots of attention. In this work, a novel isoform that encoded truncated protein due to the deletion of ABL1 exon7, 8, and 9 was reported and named BCR/ABL1ΔE7-8-9 here. This isoform was detected only in 10.2% of CML patients with inadequate responses to TKIs. BCR/ABL1Δexon7-8-9 isoform promoted S phase cell proliferation and reduced the expression of fusion gene and ABL1 phosphorylation level more slowly than that of control cells after TKIs treatment. The novel isoform has the qualities of a functional tyrosine kinase, localized in the cytoplasm, and could not be imported into the nucleus by TKIs. These results indicated that BCR/ABL1Δexon7-8-9 showed poorer sensitivity to imatinib and nilotinib than wild-type BCR/ABL1. According to molecular docking studies, nilotinib and imatinib present different binding sites and have a lower binding capacity with BCR/ABL1ΔE7-8-9 protein than the wild type. Our findings suggested that the novel isoform BCR/ABL1ΔE7-8-9 may contribute to TKIs resistance in CML due to its weakened TKIs binding ability. It enriched the mechanism of spliceosome involved in TKIs resistance. Monitoring the expression of BCR/ABL1ΔE7-8-9 helps guide the treatment of CML patients in the clinic.

Use of copula to model within-study association in bivariate meta-analysis of binomial data at the aggregate level: A Bayesian approach and application to surrogate endpoint evaluation

Bivariate meta-analysis provides a useful framework for combining information across related studies and has been utilized to combine evidence from clinical studies to evaluate treatment efficacy on two outcomes. It has also been used to investigate surrogacy patterns between treatment effects on the surrogate endpoint and the final outcome. Surrogate endpoints play an important role in drug development when they can be used to measure treatment effect early compared to the final outcome and to predict clinical benefit or harm. The standard bivariate meta-analytic approach models the observed treatment effects on the surrogate and the final outcome outcomes jointly, at both the within-study and between-studies levels, using a bivariate normal distribution. For binomial data, a normal approximation on log odds ratio scale can be used. However, this method may lead to biased results when the proportions of events are close to one or zero, affecting the validation of surrogate endpoints. In this article, we explore modeling the two outcomes on the original binomial scale. First, we present a method that uses independent binomial likelihoods to model the within-study variability avoiding to approximate the observed treatment effects. However, the method ignores the within-study association. To overcome this issue, we propose a method using a bivariate copula with binomial marginals, which allows the model to account for the within-study association. We applied the methods to an illustrative example in chronic myeloid leukemia to investigate the surrogate relationship between complete cytogenetic response and event-free-survival.

Real-world efficacy and safety outcomes of imatinib treatment in patients with chronic myeloid leukemia: An Australian experience

Tyrosine kinase inhibitors (TKI) have revolutionized the treatment of chronic myeloid leukemia (CML), but patients still experience treatment-limiting toxicities or therapeutic failure. To investigate the real-world use and outcomes of imatinib in patients with CML in Australia, a retrospective cohort study of patients with CML commencing imatinib (2001-2018) was conducted across two sites. Prescribing patterns, tolerability outcomes, and survival and molecular response were evaluated. 86 patients received 89 imatinib treatments. Dose modifications were frequently observed (12-month rate of 58%). At last follow-up, 62 patients (5-year rate of 55%) had permanently discontinued imatinib treatment, of which 44 switched to another TKI (5-year rate of 46%). Within 3 months of starting imatinib, 43% (95% CI, 32%-53%) of patients experienced imatinib-related grade ≥3 adverse drug reactions (ADRs). Higher comorbidity score, lower body weight, higher imatinib starting dose, and Middle Eastern or North African ancestry were associated with a higher risk of grade ≥3 ADR occurrence on multivariable analysis (MVA). Estimated overall survival and event-free survival rates at 3 years were 97% (95% CI, 92%-100%) and 81% (95% CI, 72%-92%), respectively. Cumulative incidence of major molecular response (MMR) at 3 years was 63% (95% CI, 50%-73%). On MVA, imatinib starting dose, ELTS score, BCR-ABL1 transcript type, pre-existing pulmonary disease, and potential drug-drug interactions were predictive of MMR. In conclusion, imatinib induced deep molecular responses that translated to good survival outcomes in a real-world setting, but was associated with a higher incidence of ADRs, dose modifications and treatment discontinuations than in clinical trials.

Patient-specific molecular response dynamics can predict the possibility of relapse during the second treatment-free remission attempt in chronic myelogenous leukemia

In chronic myelogenous leukemia (CML), treatment-free remission (TFR) is defined as maintaining a major molecular response (MMR) without a tyrosine kinase inhibitor (TKI), such as imatinib (IM). Several studies have investigated the safety of the first TFR (TFR₁) attempt and suggested recommendation guidelines for such an attempt. However, the plausibility and predictive factors for a second TFR (TFR₂) have yet to be reported. The present study included 21 patients in chronic myeloid leukemia who participated in twice repeated treatment stop attempts. We develop a mathematical model to analyze and explain the outcomes of TFR₂. Our mathematical model framework can explain patient-specific molecular response dynamics. Fitting the model to longitudinal BCR-ABL1 transcripts from the patients generated patient-specific parameters. Binary tree decision analyses of the model parameters suggested a model based predictive binary classification factor that separated patients into low- and high-risk groups of TFR₂ attempts with an overall accuracy of 76.2% (sensitivity of 81.1% and specificity of 69.9%). The low-risk group maintained a median TFR₂ of 28.2 months, while the high-risk group relapsed at a median time of 3.25 months. Further, our model predicted a patient-specific optimal IM treatment duration before the second IM stop that could achieve the desired TFR₂ (e.g., 5 years).

A Ten-Year Experience of Treating Chronic Myeloid Leukemia in Rural Rwanda: Outcomes and Insights for a Changing Landscape

PURPOSE

In describing our ten-year experience with treating chronic myeloid leukemia (CML) as part of the Glivec Patient Assistance Program (GIPAP) in rural Rwanda, we evaluate (1) patient characteristics and treatment outcomes, (2) resource-adapted management strategies, and (3) the impact of diagnostic capacity development.

METHODS

We retrospectively reviewed all patients with BCR-ABL-positive CML enrolled in this GIPAP program between 2009 and 2018. Clinical data were analyzed using descriptive statistics, Kaplan-Meier methods, proportional hazards regression, and the Kruskal-Wallis test.

RESULTS

One hundred twenty-four patients were included. The median age at diagnosis was 34 (range 8-81) years. On imatinib, 91% achieved complete hematologic response (CHR) after a median of 49 days. Seven (6%) and 12 (11%) patients had primary and secondary imatinib resistance, respectively. The 3-year overall survival was 80% (95% CI, 72 to 87) for the cohort, with superior survival in imatinib responders compared with those with primary and secondary resistance. The median time from imatinib initiation to CHR was 59 versus 38 days (P = .040) before and after in-country diagnostic testing, whereas the median time to diagnosis (P = .056) and imatinib initiation (P = .170) was not significantly different.

CONCLUSION

Coupling molecular diagnostics with affordable access to imatinib within a comprehensive cancer care delivery program is a successful long-term strategy to treat CML in resource-constrained settings. Our patients are younger and have higher rates of imatinib resistance compared with historic cohorts in high-income countries. High imatinib resistance rates highlight the need for access to molecular monitoring, resistance testing, and second-generation tyrosine kinase inhibitors, as well as systems to support drug adherence. Hematologic response is an accurate resource-adapted predictor of survival in this setting. Local diagnostic capacity development has allowed for continuous, timely CML care delivery in Rwanda.

Brazilian chronic myeloid leukemia working group recommendations for discontinuation of tyrosine kinase inhibitors in chronic myeloid leukemia in clinical practice

Introduction

Treatment-free remission (TFR) is a new goal of chronic myeloid leukemia (CML) therapy. TFR is feasible when the patient has achieved a deep and stable molecular response and met the criteria required to ensure its success. Treatment discontinuation should not be proposed to the CML patient if minimum conditions are not met. In Brazil, for example, molecular tests (BCR::ABL1) are not broadly available, making it difficult to monitor the patients adequately.

Objective

In this sense, providing TFR recommendations for Brazilian physicians are therefore necessary. These recommendations include the main criteria checklist to start the TKIs treatment discontinuing process in patients diagnosed with CML and the population-eligible characteristics for treatment discontinuation.

Method

Age, risk score at diagnosis, TKI treatment duration, BCR::ABL1 transcripts type, depth of the molecular response for treatment discontinuation, treatment adherence, patient monitoring and withdrawal syndrome are essential factors to consider in TFR. After TKI discontinuation, BCR::ABL1 transcripts monitoring should be more frequent. When a major molecular response loss is observed during the monitoring of a patient in TFR, the TKI treatment should be resumed.

Conclusion

These recommendations should serve as a basis for medical professionals interested in proposing TKI discontinuation for CML patients in clinical practice. It is important to highlight that, despite the benefits of TFR for the patients and the health system, it should only be feasible following the minimum standards proposed in this recommendation.

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.

Eliminating chronic myeloid leukemia stem cells by IRAK1/4 inhibitors

Leukemia stem cells (LSCs) in chronic myeloid leukemia (CML) are quiescent, insensitive to BCR-ABL1 tyrosine kinase inhibitors (TKIs) and responsible for CML relapse. Therefore, eradicating quiescent CML LSCs is a major goal in CML therapy. Here, using a G₀ marker (G₀M), we narrow down CML LSCs as G₀M- and CD27- double positive cells among the conventional CML LSCs. Whole transcriptome analysis reveals NF-κB activation via inflammatory signals in imatinib-insensitive quiescent CML LSCs. Blocking NF-κB signals by inhibitors of interleukin-1 receptor-associated kinase 1/4 (IRAK1/4 inhibitors) together with imatinib eliminates mouse and human CML LSCs. Intriguingly, IRAK1/4 inhibitors attenuate PD-L1 expression on CML LSCs, and blocking PD-L1 together with imatinib also effectively eliminates CML LSCs in the presence of T cell immunity. Thus, IRAK1/4 inhibitors can eliminate CML LSCs through inhibiting NF-κB activity and reducing PD-L1 expression. Collectively, the combination of TKIs and IRAK1/4 inhibitors is an attractive strategy to achieve a radical cure of CML.

Enabling access to molecular monitoring for chronic myeloid leukemia patients is cost effective in China

Objective

To determine the cost effectiveness of molecular monitoring in patients with chronic myeloid leukemia in the chronic phase (CML-CP) compared to no molecular monitoring from a Chinese payer perspective.

Methods

Analyses were conducted using a semi-Markov model with a 50-year time horizon. Population data from multicenter registry-based studies of Chinese patients with CML-CP informed the model. Transition probabilities were based on time-to-event data from the literature. Utility values were obtained from published studies and were assumed to be the same for patients with and without molecular monitoring. Costs were based on values commonly used in the Chinese healthcare system, including drug acquisition, drug administration, follow-up, treatment for disease progression, molecular monitoring, and terminal care costs, and were in the local currency (2020 Chinese Yuan RMB [¥]). Outcomes were total life-years (LYs) and quality-adjusted life years (QALYs), lifetime costs, and incremental cost-effectiveness ratio.

Results

Molecular monitoring was dominant to no molecular monitoring, with increased LYs (1.52) and QALYs (1.90) and costs savings (¥93,840) over a lifetime compared to no monitoring in discounted analyses. The opportunity of patients that receive molecular monitoring to discontinue treatment during treatment-free remission, an opportunity not afforded to those without molecular monitoring, was the principle driver of this result. Results were similar across multiple clinical scenarios. Particularly, molecular monitoring remained dominant even if the proportion of patients achieving deep molecular response (DMR) was reduced by 10%-30%, or the proportion of patients maintaining DMR for 1 year was reduced by 10%-30% or increased by 10%. Cost savings in these scenarios ranged from ¥62,230 to ¥103,964.

Conclusions

Overall, this analysis demonstrates that adherence to guideline recommendations of regular molecular monitoring of patients with CML-CP treated with TKIs provides significant clinical benefit that leads to substantial cost savings compared to no molecular monitoring from the perspective of a Chinese payer. In a time where healthcare systems have limited resources to allocate to optimal patient care, investment in molecular monitoring is an ideal choice for improving patient benefits at a reduced cost.

Analysis of ceRNA networks and identification of potential drug targets for drug-resistant leukemia cell K562/ADR

Background

Drug resistance is the main obstacle in the treatment of leukemia. As a member of the competitive endogenous RNA (ceRNA) mechanism, underlying roles of lncRNA are rarely reported in drug-resistant leukemia cells.

Methods

The gene expression profiles of lncRNAs and mRNAs in doxorubicin-resistant K562/ADR and sensitive K562 cells were established by RNA sequencing (RNA-seq). Expression of differentially expressed lncRNAs (DElncRNAs) and DEmRNAs was validated by qRT-PCR. The potential biological functions of DElncRNAs targets were identified by GO and KEGG pathway enrichment analyses, and the lncRNA-miRNA-mRNA ceRNA network was further constructed. K562/ADR cells were transfected with CCDC26 and LINC01515 siRNAs to detect the mRNA levels of GLRX5 and DICER1, respectively. The cell survival rate after transfection was detected by CCK-8 assay.

Results

The ceRNA network was composed of 409 lncRNA-miRNA pairs and 306 miRNA-mRNA pairs based on 67 DElncRNAs, 58 DEmiRNAs and 192 DEmRNAs. Knockdown of CCDC26 and LINC01515 increased the sensitivity of K562/ADR cells to doxorubicin and significantly reduced the half-maximal inhibitory concentration (IC₅₀) of doxorubicin. Furthermore, knockdown of GLRX5 and DICER1 increased the sensitivity of K562/ADR cells to doxorubicin and significantly reduced the IC₅₀ of doxorubicin.

Conclusions

The ceRNA regulatory networks may play important roles in drug resistance of leukemia cells. CCDC26/miR-140-5p/GLRX5 and LINC01515/miR-425-5p/DICER1 may be potential targets for drug resistance in K562/ADR cells. This study provides a promising strategy to overcome drug resistance and deepens the understanding of the ceRNA regulatory mechanism related to drug resistance in CML cells.

Real-life comparison of nilotinib versus dasatinib as second-line therapy in chronic phase chronic myeloid leukemia patients

Tyrosine kinase inhibitors (TKIs), the backbone of treatment for chronic phase chronic myeloid leukemia patients (CP-CML), have changed the long-term outcome of the disease. Nonetheless, over 20% of patients fail front-line therapy due to intolerance or resistance. A head-to-head comparison of dasatinib and nilotinib as second-line treatment outside of sponsored clinical trials has not been reported. We retrospectively analyzed 131 CP-CML patients who, after front-line imatinib failure, switched to a second-line therapy with nilotinib (59, 45%) or dasatinib (72, 55%). Median duration of second-line treatment was 33 months (range 2-100). The reason for switching therapy was resistance in 83.2% and intolerance in 16.8% of patients. The overall survival of the entire cohort at 7 years was 78.9%, while it was 72% and 85.6% for patients treated with dasatinib and nilotinib, respectively (p=0.287). With regard to efficacy after 12 months of treatment, 108 patients were evaluable for molecular response: 47% achieved a major molecular response and 18.2% a deep molecular response with dasatinib, compared to 38% and 16.2% with nilotinib (p=ns). We observed 35% of grade 3-4 adverse events, more frequently in the dasatinib group (47%) compared to the nilotinib group (22%), without affecting molecular responses. Our study suggests that, in the real-life setting, dasatinib and nilotinib used as second-line treatment in CP-CML are equally effective, with high molecular response rates and an acceptable tolerability.

The regulation of bcr-abl in hypoxia is through the mTOR pathway

Chronic myeloid leukemia (CML) is usually characterized by the formation of the fusion onco-protein bcr-abl. Therefore, the majority of CML treatments are bcr-abl specific tyrosine kinase inhibitors (TKIs). TKI resistance in CML treatment is becoming a major obstacle in managing this disease. One well-studied form of drug resistance is hypoxia-induced drug resistance, a phenomenon observed in many other cancers. This study aimed to determine the efficacy of TKIs in CML cells cultured in hypoxia. It was observed that bcr-abl translation was severely halted in hypoxia, rendering TKIs ineffective. We found that the mechanism by which bcr-abl protein levels were being suppressed in hypoxia was through the mTOR pathway, specifically via ribosomal protein S6 (RPS6). This information is vital to the improvement of CML treatments, as it can be used to determine how to best combat hypoxia-induced drug resistance in CML and subsequently to identify new targets for treatment.

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

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

Bcr-Abl Tyrosine Kinase Inhibitors in the Treatment of Pediatric CML

The therapeutic approach to Chronic Myeloid Leukemia (CML) has changed since the advent of the tyrosine kinase inhibitor (TKI) imatinib, which was then followed by the second generation TKIs dasatinib, nilotinib, and, finally, by ponatinib, a third-generation drug. At present, these therapeutic options represent the first-line treatment for adults. Based on clinical experience, imatinb, dasatinib, and nilotinib have been approved for children even though the studies that were concerned with efficacy and safety toward pediatric patients are still awaiting more specific and high-quality data. In this scenario, it is of utmost importance to prospectively validate data extrapolated from adult studies to set a standard therapeutic management for pediatric CML by employing appropriate formulations on the basis of pediatric clinical trials, which allow a careful monitoring of TKI-induced adverse effects especially in growing children exposed to long-term therapy.

How many chronic myeloid leukemia patients who started a frontline second-generation tyrosine kinase inhibitor have to switch to a second-line treatment? A retrospective analysis from the monitoring registries of the italian medicines agency (AIFA)

The frequency of patients who switch to a second‐line therapy from a frontline second‐generation (2gen) tyrosine kinase inhibitor (TKI) such as dasatinib and nilotinib, is still substantially unknown. We retrospectively investigated a large series of chronic phase chronic myeloid leukemia (CP‐CML) patients initially treated with 2gen TKIs monitored through the Italian Medicines Agency (AIFA Agenzia Italiana del farmaco) registries. Overall, 2420 patients were analyzed over a period of 6 years. One hundred and fifty‐seven patients (16.3%) treated with dasatinib and 164 treated with nilotinib (11.3%) have switched to another drug, with an overall frequency of 13.2%. In the dasatinib cohort, 39.4% of patients changed treatment for failure and 36.3% for intolerance as compared to 45.7% and 27.4% respectively in the nilotinib cohort. Overall, the median time to switch due to resistance was 293 days, whereas it was 317 days in case of intolerance. Resistance was observed mainly in younger male patients with high‐risk features, while intolerance was not related to any baseline parameter. After resistance/intolerance to nilotinib, the majority of patients switched to dasatinib (53.8%) whereas in case of frontline dasatinib to ponatinib (43.2%). To the best of our knowledge these data provide the first report on the frequency of discontinuation of frontline 2gen TKIs and on the main causes and pattern of choice to a second‐line therapy in the real‐life setting.

Validation of the EUTOS Long-Term Survival Score in Chinese Chronic Myeloid Leukemia Patients Treated with Imatinib: A Multicenter Real-World Study

Purpose

To validate the clinical efficacy of the recently developed EUTOS long-term survival (ELTS) score in a real-world setting.

Patients and Methods

A total of 479 chronic myeloid leukemia (CML) patients treated with frontline imatinib between January 2010 and December 2017 were enrolled in this retrospective study. The ELTS score was evaluated on the end-points including complete cytogenetic response (CCyR), progression-free survival (PFS), overall survival (OS) and CML-related death, and the efficiency of the ELTS score was further compared with the historical Sokal, Hasford, EUTOS scores.

Results

With a median follow-up of 69 months (range, 9–112 months), 462 evaluable patients were stratified into the ELTS low-risk (n = 230), ELTS intermediate-risk (n = 168) and ELTS high-risk (n = 64) groups. For the regular assessment indicators like CCyR, PFS and OS, the ELTS scoring system could effectively identify the corresponding risk groups, similarly with the results provided by previous scoring systems. With respect to the CML-related death, the ELTS score could accurately identify a high-risk group with a significantly higher risk of dying of CML, and the 5-year cumulative incidence occurred in the ELTS high-, intermediate-, and low-risk groups was 11% (95% CI: 3–19%), 5% (95% CI: 1–9%) and 2% (95% CI: 0–4%), respectively. Most notably, the ELTS score outperformed the Sokal, Hasford and EUTOS scores without statistical difference among different risk groups.

Conclusion

The ELTS score could effectively predict the prognosis of imatinib-treated CML patients in real-life settings.

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

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

Clinical efficacy and safety of imatinib treatment in children and adolescents with chronic myeloid leukemia: A single-center experience in China

Chronic myeloid leukemia (CML) is relatively rare in childhood and few studies have reported the clinical use of imatinib (IM) in pediatric CML. In this study, we evaluated the efficacy and tolerability of IM in children and adolescents with CML.We investigated 21 patients under 18 years of age with newly diagnosed CML and treated with IM in Children's Hospital of Chongqing Medical University between May 2014 and February 2018. The disease was staged according to the European LeukemiaNet criteria and the IM dose was determined based on the disease stage. Cumulative responses and survival probabilities were estimated according to the Kaplan-Meier method.The estimated complete hematologic response rate of chronic phase-chronic myeloid leukemia (CML-CP) was 89.5% at 3 months. The complete cytogenetic response rates increased with time, reaching 47.4%, 73.7%, and 80.3% at 6, 12, and 24 months, respectively. The cumulative major molecular response rates were 42.1% and 76.3% at 12 and 24 months, respectively. With a median follow-up time of 33.8 months (range, 3.2-61.7 months), the estimated 2-year overall survival (OS) rate for CML was 95.2% (95% confidence interval [CI], 70.7%-99.3%). None of the CML-CP patients progressed to the accelerated phase or had a blast crisis. The 2-year OS and progression-free survival rates for the CML-CP cohort were both 100%, while the estimated 2-year event-free survival rate was 68% (95% CI, 42.1%-84.2%). None of the patients in this group had treatment-related deaths or IM discontinuation due to drug toxicities, and only 1 patient had a grade III-IV nonhematologic adverse event. Overall, anemia was the most common adverse effect and 42.9% of patients had a decrease in bone mineral density.IM was effective and the adverse effects were well-tolerated throughout the follow-up period in Chinese CML patients under 18 years of age.

Betulinic acid restores imatinib sensitivity in BCR-ABL1 kinase-independent, imatinib-resistant chronic myeloid leukemia by increasing HDAC3 ubiquitination and degradation

Although imatinib (IM) has been demonstrated to be an efficient treatment in chronic myeloid leukemia (CML), some patients still experience IM resistance and disease relapse. Through in vitro studies, we observed that HDAC3 levels were elevated in BCR-ABL1 kinase-independent, IM-resistant primary cells from CML patients and in IM-resistant K562 (K562R) cells and that downregulation of HDAC3 could enhance IM efficacy in K562R cells. Furthermore, betulinic acid (BA), a lupane-type pentacyclic triterpenoid saponin isolated from birch trees, restored IM sensitivity in the BCR-ABL1 kinase-independent, IM-resistant primary cells and in K562R cells, as well as in primary CD34⁺ bone marrow cells from CML patients. We found that BA restored IM sensitivity through inhibition of HDAC3 accumulation in cells, and that this was mediated by BA-dependent ubiquitination and degradation of HDAC3. BA at low dosage significantly increased IM antitumor effects on murine xenografts bearing K562R cells and inhibited HDAC3 expression in tumor tissue. Our findings demonstrated that HDAC3 is an essential factor in BCR-ABL1 kinase-independent IM resistance, and that BA in combination with IM may be a novel treatment strategy for overcoming IM resistance in CML.

A second-generation TKI should always be used as initial therapy for CML

This article has a companion Point by Hantel and Larson.

Assessing Measurable Residual Disease in Chronic Myeloid Leukemia. BCR-ABL1 IS in the Avant-Garde of Molecular Hematology

Chronic myelogenous leukemia (CML) is a malignancy of the myeloid cell lineage characterized by a recurrent chromosomal abnormality: the Philadelphia chromosome, which results from the reciprocal translocation of the chromosomes 9 and 22. The Philadelphia chromosome contains a fusion gene called BCR-ABL1. The BCR-ABL1 codes for an aberrantly functioning tyrosine kinase that drives the malignant proliferation of the founding clone. The advent of tyrosine kinase inhibitors (TKI) represents a landmark in the treatment of CML, that has led to tremendous improvement in the remission and survival rates. Since the introduction of imatinib, the first TKI, several other TKI have been approved that further broadened the arsenal against CML. Patients treated with TKIs require sensitive monitoring of BCR-ABL1 transcripts with quantitative real-time polymerase chain reaction (qRT-PCT), which has become an essential part of managing patients with CML. In this review, we discuss the importance of the BCR-ABL1 assay, and we highlight the growing importance of BCR-ABL1 dynamics. We also introduce a mathematical correction for the BCR-ABL1 assay that could help homogenizing the use of the ABL1 as a control gene. Finally, we discuss the growing body of evidence concerning treatment-free remission. Along with the continuous improvement in the therapeutic arsenal against CML, the molecular monitoring of CML represents the avant-garde in the struggle to make CML a curable disease.

Effect of low-level BCR-ABL1 kinase domain mutations identified by next-generation sequencing in patients with chronic myeloid leukaemia: a population-based study

BACKGROUND

Kinase domain mutations in BCR-ABL1 are associated with resistance to tyrosine kinase inhibitors in patients with chronic myeloid leukaemia. Next-generation sequencing (NGS) allows detection of low-level kinase domain mutations, but its relevance in clinical practice remains debated. We aimed to examine the clinical effects of low-level kinase domain mutations identified using NGS in patients with chronic myeloid leukaemia.

METHODS

In this population-based study, we included consecutive patients newly diagnosed with chronic myeloid leukaemia treated with first-line tyrosine kinase inhibitors, and patients identified at the time of resistance to first-line treatment with imatinib at six institutions (teaching hospitals and district hospitals) in southeast England. We screened patients for BCR-ABL1 kinase domain mutations using NGS, irrespective of patient response to tyrosine kinase inhibitor therapy. When we detected a mutation with NGS, we retrospectively analysed all previous samples to establish the date of first occurrence and subsequent kinetics of the mutant subclone (or subclones). The primary endpoints of this study were progression-free and event-free survival at 5 years.

FINDINGS

Between Feb 1, 2007, and Dec 31, 2014, we screened 121 patients with chronic myeloid leukaemia for BCR-ABL1 kinase domain mutation. 99 consecutive patients were newly diagnosed, with available sequential RNA stored. The remaining 22 patients were diagnosed between June 1, 1999, and June 30, 2006, and were screened at the time of resistance to first-line treatment with imatinib. Imatinib was the first-line treatment for 111 patients, nilotinib for seven patients, and dasatinib for three patients. We detected a kinase domain mutation in 25 (21%) of 121 patients. Low-level kinase domain mutations were first identified in 17 (68%) of 25 patients with mutation. For patients with a complete cytogenetic response, 13 (14%) of 93 patients screened had a mutation. Five (71%) of the seven patients with a clinically relevant mutation lost complete cytogenetic response compared with 15 (17%) of 86 patients without a clinically relevant mutation (80 patients without mutation and six patients with a tyrosine kinase inhibitor-sensitive mutation, p=0·0031). Patients harbouring a mutant clone had poorer 5-year progression-free survival (65·3% [95% CI 40·5-81·8] vs 86·9% [75·8-93·2]; p=0·0161) and poorer 5-year event-free survival (22·2% [CI 5·6-45·9] vs 62·0% [50·4-71·6]; p<0·0001) than did patients without a mutation. We identified a kinase domain mutation in four (10%) of 41 patients with samples available at 3 months after starting first-line tyrosine kinase inhibitor treatment; all four subsequently progressed to accelerated phase disease compared with only three (8%) of 37 without a mutation (p<0·0001).

INTERPRETATION

NGS reliably and consistently detected early appearance of kinase domain mutations that would not otherwise be detected by Sanger sequencing. For the first time, to our knowledge, we report the presence of kinase domain mutations after only 3 months of therapy, which could have substantial clinical implications. NGS will allow early clinical intervention and our findings will contribute to the establishment of new recommendations on the frequency of kinase domain mutation analysis to improve patient clinical care.

FUNDING

None.

Phosphorylation of BECLIN-1 by BCR-ABL suppresses autophagy in chronic myeloid leukemia

Autophagy is a genetically regulated process of adaptation to metabolic stress and was recently shown to be involved in the treatment response of chronic myeloid leukemia (CML). However, in vivo data are limited and the molecular mechanism of autophagy regulators in the process of leukemogenesis is not completely understood. Here we show that Beclin-1 knockdown, but not Atg5 deletion in a murine CML model leads to a reduced leukemic burden and results in a significantly prolonged median survival of targeted mice. Further analyses of murine cell lines and primary patient material indicate that active BCR-ABL directly interacts with BECLIN-1 and phosphorylates its tyrosine residues 233 and 352, resulting in autophagy suppression. By using phosphorylation-deficient and phosphorylation-mimic mutants, we identify BCR-ABL induced BECLIN-1 phosphorylation as a crucial mechanism for BECLIN-1 complex formation: interaction analyses exhibit diminished binding of the positive autophagy regulators UVRAG, VPS15, ATG14 and VPS34 and enhanced binding of the negative regulator Rubicon to BCR-ABL-phosphorylated BECLIN-1. Taken together, our findings show interaction of BCR-ABL and BECLIN-1 thereby highlighting the importance of BECLIN-1-mediated autophagy in BCR-ABL⁺ cells.

Newer-Generation EGFR Inhibitors in Lung Cancer: How Are They Best Used?

The FLAURA trial established osimertinib, a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), as a viable first-line therapy in non-small cell lung cancer (NSCLC) with sensitizing EGFR mutations, namely exon 19 deletion and L858R. In this phase 3 randomized, controlled, double-blind trial of treatment-naïve patients with EGFR mutant NSCLC, osimertinib was compared to standard-of-care EGFR TKIs (i.e., erlotinib or gefinitib) in the first-line setting. Osimertinib demonstrated improvement in median progression-free survival (18.9 months vs. 10.2 months; hazard ratio 0.46; 95% CI, 0.37 to 0.57; p < 0.001) and a more favorable toxicity profile due to its lower affinity for wild-type EGFR. Furthermore, similar to later-generation anaplastic lymphoma kinase (ALK) inhibitors, osimertinib has improved efficacy against brain metastases. Despite this impressive effect, the optimal sequencing of osimertinib, whether in the first line or as subsequent therapy after the failure of earlier-generation EGFR TKIs, is not clear. Because up-front use of later-generation TKIs may result in the inability to use earlier-generation TKIs, this treatment paradigm must be evaluated carefully. For EGFR mutant NSCLC, considerations include the incidence of T790M resistance mutations, quality of life, whether there is a potential role for earlier-generation TKIs after osimertinib failure, and overall survival. This review explores these issues for EGFR inhibitors and other molecularly targeted therapies.

Stem cell persistence in CML is mediated by extrinsically activated JAK1-STAT3 signaling

Tyrosine kinase inhibitor (TKI) therapy effectively blocks oncogenic Bcr-Abl signaling and induces molecular remission in the majority of CML patients. However, the disease-driving stem cell population is not fully targeted by TKI therapy in the majority of patients, and leukemic stem cells (LSCs) capable of re-inducing the disease can persist. In TKI-resistant CML, STAT3 inhibition was previously shown to reduce malignant cell survival. Here, we show therapy-resistant cell-extrinsic STAT3 activation in TKI-sensitive CML cells, using cell lines, HoxB8-immortalized murine BM cells, and primary human stem cells. Moreover, we identified JAK1 but not JAK2 as the STAT3-activating kinase by applying JAK1/2 selective inhibitors and genetic inactivation. Employing an IL-6-blocking peptide, we identified IL-6 as a mediator of STAT3 activation. Combined inhibition of Bcr-Abl and JAK1 further reduced CFUs from murine CML BM, human CML MNCs, as well as CD34⁺ CML cells, and similarly decreased LT-HSCs in a transgenic CML mouse model. In line with these observations, proliferation of human CML CD34⁺ cells was strongly reduced upon combined Bcr-Abl and JAK1 inhibition. Remarkably, the combinatory therapy significantly induced apoptosis even in quiescent LSCs. Our findings suggest JAK1 as a potential therapeutic target for curative CML therapies.

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.

Mitochondrial Hyperactivation and Enhanced ROS Production are Involved in Toxicity Induced by Oncogenic Kinases Over-Signaling

Targeted therapy is an effective, rational, and safe approach to solid and hematological tumors treatment. Unfortunately, a significant fraction of patients treated with tyrosine kinase inhibitors (TKI) relapses mainly because of gene amplification, mutations, or other bypass mechanisms. Recently a growing number of papers showed how, in some cases, resistance due to oncogene overexpression may be associated with drug addiction: cells able to proliferate in the presence of high TKI doses become also TKI dependent, undergoing cellular stress, and apoptosis/death upon drug withdrawal. Notably, if a sub-cellular population survives TKI discontinuation it is also partially re-sensitized to the same drug. Thus, it is possible that a subset of patients relapsing upon TKI treatment may benefit from a discontinuous therapeutic schedule. We focused on two different hematologic malignancies, chronic myeloid leukemia (CML) and anaplastic large cell lymphoma (ALCL), both successfully treatable with TKIs. The two models utilized (LAMA and SUP-M2) differed in having oncogene overexpression as the sole cause of drug resistance (CML), or additionally carrying kinase domain mutations (ALCL). In both cases drug withdrawal caused a sudden overload of oncogenic signal, enhanced mitochondria activity, induced the release of a high amount of reactive oxygen species (ROS), and caused genotoxic stress and massive cell death. In LAMA cells (CML) we could rescue the cells from death by partially blocking downstream oncogenic signaling or lowering ROS detrimental effect by adding reduced glutathione.

Sequential use of second-generation tyrosine kinase inhibitors following imatinib therapy in pediatric chronic myeloid leukemia: A report from the Japanese Pediatric Leukemia/Lymphoma Study Group

BACKGROUND

The details of the sequential use of imatinib for first-line treatment followed by second-generation tyrosine kinase inhibitors (2G-TKIs) for pediatric chronic myeloid leukemia (CML) are still unknown. This study analyzed clinical responses and adverse effects of the use of 2G-TKIs following imatinib in pediatric chronic phase (CP)-CML.

PROCEDURES

The Japanese Pediatric Leukemia/Lymphoma Study Group conducted a retrospective study of patients with newly diagnosed CML from 1996 to 2011. A total of 152 cases that received imatinib as first-line therapy were analyzed.

RESULTS

Excluding 46 cases treated with hematopoietic stem cell transplantation before nilotinib and dasatinib became available, 31 of 106 patients changed to 2G-TKIs. The primary reason for changing from imatinib was poor response, followed by intolerance, with the main reason for the latter being musculoskeletal events. Switches from imatinib to 2G-TKIs with intolerance occurred significantly earlier than switches with poor response. Sixteen and 15 patients were treated with nilotinib and dasatinib, respectively, following imatinib therapy. After switching to 2G-TKIs, the response status improved in 63% of evaluable patients. The adverse effect profiles of nilotinib and dasatinib tended to be different, with hyperbilirubinemia observed in 33% of nilotinib-treated patients, but in none of the cases with dasatinib.

CONCLUSION

This retrospective study represents the first series of children and adolescents in whom sequential use of imatinib followed by 2G-TKIs was reported. These data provide useful insights into the selection of 2G-TKIs as first-line treatment for children and adolescents with CP-CML.

Comparative analysis of the Sokal, Euro and European Treatment and Outcome Study score in prognostication of Indian chronic myeloid leukemia-chronic phase patients on imatinib

Introduction:

The ultimate goal for CML management is risk stratification of the patients to design the appropriate treatment approach. The Sokal, Euro and EUTOS risk scores were established to prognosticate the patients on therapy.

Aim:

To perform a comparative assessment of the Sokal, Euro and EUTOS prognostic score in Indian CML-CP patients on imatinib.

Methods:

This is a retrospective study performed in 260 Ph+ CML-CP patients who were administered oral imatinib (400 mg/day).

Results:

166/260 were males and 94/260 were females (M: F::1.6:1) with median age 35 years (range 20-70). 92 (35.38%), 125 (48.07%) and 43 (16.5%) patients were divided into low, intermediate and high risk Sokal score respectively. 102 (39.23%), 106 (40.76%) and 52 (20%) patients were discriminated into low, intermediate and high risk Euro score respectively. 210 (80.7%) and 50 (19.2%) patients were divided into low and high risk EUTOS score. Cumulative incidence of MMR for low, intermediate and high-risk Sokal score was 87%, 76% and 84% respectively (P = 0.016). Incidence of MMR in low, intermediate and high-risk Euro score was 93%, 85% and 68% respectively (P = 0.001). Incidence of MMR was 80 % and 81% for low and high risk EUTOS score (P = 0.764). Both EFS and OS are significantly correlated with Sokal score (P = 0.004, P = 0.007) and Euro score (P = 0.009, P = 0.001) but not with EUTOS score (P = 0.581, P = 0.927).

Conclusion:

The present study highlights the significant prognostic role of Sokal and Euro score in predicting the treatment outcome of the CML- CP patients on imatinib.

The significance of enzyme and transporter polymorphisms for imatinib plasma levels and achieving an optimal response in chronic myeloid leukemia patients

INTRODUCTION

Imatinib mesylate is the drug of choice for patients with chronic myeloid leukemia (CML). Imatinib pharmacokinetics is affected by a number of transport proteins and enzymes.

MATERIAL AND METHODS

In the present study we evaluated the association of eight polymorphisms in the seven genes CYP3A5*3 (rs776746), CYP3A4*1 (rs2740574), CYP2C9*3 (rs1057910), SLC22A1 (rs683369), ABCB1 (rs1045642, rs1128503), ABCG2 (rs2231142) and ABCC2 (rs717620) with imatinib plasma level and achieving an optimal clinical response in 112 CML patients (53 men and 59 women).

RESULTS

No association was found between the examined polymorphisms in rs776746, rs2740574, rs1057910, rs683369, rs1045642, rs1128503, rs2231142, rs717620 and the achieved imatinib plasma level. The influence of rs776746 (CYP3A5*3) on the achievement of a complete cytogenetic response (CCyR) at 6 months was borderline non-significant (p = 0.06). Furthermore, no association was demonstrated between rs776746 polymorphisms and the achievement of a major molecular response (MMR) at 12 or 18 months. Polymorphisms rs776746, rs2740574, rs1057910, rs683369, rs1045642, rs1128503, rs2231142, rs717620 showed no impact on the optimal therapeutic response.

CONCLUSIONS

Despite the results of some other studies, no other polymorphism we analyzed was associated with imatinib plasma level or clinical response. The treatment outcomes cannot be predicted using the candidate gene approach and treatment decisions cannot be made according to the polymorphisms investigated in this study.

Four-year follow-up of patients with imatinib-resistant or intolerant chronic myeloid leukemia receiving dasatinib: efficacy and safety

Dasatinib is a highly effective second-generation tyrosine kinase inhibitor used to treat chronic myeloid leukemia (CML). In 2007, a pivotal phase-2 study of dasatinib as second-line treatment was initiated in 140 Chinese CML patients. This report from the 4-year follow-up revealed that 73% of 59 patients in chronic phase (CML-CP) and 32% of 25 patients in accelerated phase (CML-AP) remained under treatment. The initial dosage of dasatinib for CML-CP and CML-AP patients were 100 mg once daily and 70 mg twice daily (total = 140 mg/ day), respectively. The cumulative major cytogenetic response (MCyR) rate among patients with CML-CP was 66.1% (versus 50.8% at 18 months), and the median time to MCyR was 12.7 weeks. All CML-CP patients who achieved MCyR after a 4-year follow-up also achieved a complete cytogenetic response. The cumulative complete hematological response (CHR) rate among patients with CML-AP was 64% (16/25), with three CML-AP patients achieving CHR between 18 months and 4 years of follow-up; the median time to CHR was 16.4 weeks. The adverse event (AE) profile of dasatinib at 4 years was similar to that at 6 and 18 months. The most frequently reported AEs (any grade) included pleural effusion, headache, and myelosuppression. These long-term follow-up data continue to support dasatinib as a second-line treatment for Chinese patients with CML.

Imatinib trough levels: a potential biomarker to predict cytogenetic and molecular response in newly diagnosed patients with chronic myeloid leukemia

Therapeutic drug monitoring of imatinib in patients with chronic myeloid leukemia (CML) is an ongoing debate. We studied the influence of imatinib trough levels on therapeutic response in 206 newly diagnosed patients with CML. We also compared the drug levels in patients taking branded and generic imatinib. Imatinib levels were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Marked inter-individual variability was seen in imatinib levels (coefficient of variation = 69%). Trough levels were significantly higher in patients who attained complete cytogenetic response than those who did not (2213.9 ± 1101 vs. 1648.6 ± 1403.4ng/mL; p < .001). Patients with major molecular response (MMR) had higher trough levels than those without MMR (2333.4 ± 1112 vs. 1643.4 ± 1383.9ng/mL; p = .001). Patients with trough levels ≤1000ng/mL were at high risk for failure of imatinib therapy [RR =1.926; 95%CI (1.562, 2.374); p < .001]. Trough levels emerged as an independent predictor of imatinib response in multivariate analysis. To conclude, imatinib trough levels significantly influence cytogenetic and molecular response and might emerge as a potential biomarker for therapeutic response in CML.