Resistant mutations in CML and Ph(+)ALL - role of ponatinib

Angiogenic signaling pathways and anti-angiogenic therapy for cancer

Angiogenesis, the formation of new blood vessels, is a complex and dynamic process regulated by various pro- and anti-angiogenic molecules, which plays a crucial role in tumor growth, invasion, and metastasis. With the advances in molecular and cellular biology, various biomolecules such as growth factors, chemokines, and adhesion factors involved in tumor angiogenesis has gradually been elucidated. Targeted therapeutic research based on these molecules has driven anti-angiogenic treatment to become a promising strategy in anti-tumor therapy. The most widely used anti-angiogenic agents include monoclonal antibodies and tyrosine kinase inhibitors (TKIs) targeting vascular endothelial growth factor (VEGF) pathway. However, the clinical benefit of this modality has still been limited due to several defects such as adverse events, acquired drug resistance, tumor recurrence, and lack of validated biomarkers, which impel further research on mechanisms of tumor angiogenesis, the development of multiple drugs and the combination therapy to figure out how to improve the therapeutic efficacy. Here, we broadly summarize various signaling pathways in tumor angiogenesis and discuss the development and current challenges of anti-angiogenic therapy. We also propose several new promising approaches to improve anti-angiogenic efficacy and provide a perspective for the development and research of anti-angiogenic therapy.

Designing Novel BCR-ABL Inhibitors for Chronic Myeloid Leukemia with Improved Cardiac Safety

Development of tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL oncogene constitutes an effective approach for the treatment of chronic myeloid leukemia (CML) and/or acute lymphoblastic leukemia. However, currently available inhibitors are limited by drug resistance and toxicity. Ponatinib, a third-generation inhibitor, has demonstrated excellent efficacy against both wild type and mutant BCR-ABL kinase, including the "gatekeeper" T315I mutation that is resistant to all other currently available TKIs. However, it is one of the most cardiotoxic of the FDA-approved TKIs. Herein, we report the structure-guided design of a novel series of potent BCR-ABL inhibitors, particularly for the T315I mutation. Our drug design paradigm was coupled to iPSC-cardiomyocyte models. Systematic structure-activity relationship studies identified two compounds, 33a and 36a, that significantly inhibit the kinase activity of both native BCR-ABL and the T315I mutant. We have identified the most cardiac-safe TKIs reported to date, and they may be used to effectively treat CML patients with the T315I mutation.

JAK2 Alterations in Acute Lymphoblastic Leukemia: Molecular Insights for Superior Precision Medicine Strategies

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer, arising from immature lymphocytes that show uncontrolled proliferation and arrested differentiation. Genomic alterations affecting Janus kinase 2 (JAK2) correlate with some of the poorest outcomes within the Philadelphia-like subtype of ALL. Given the success of kinase inhibitors in the treatment of chronic myeloid leukemia, the discovery of activating JAK2 point mutations and JAK2 fusion genes in ALL, was a breakthrough for potential targeted therapies. However, the molecular mechanisms by which these alterations activate JAK2 and promote downstream signaling is poorly understood. Furthermore, as clinical data regarding the limitations of approved JAK inhibitors in myeloproliferative disorders matures, there is a growing awareness of the need for alternative precision medicine approaches for specific JAK2 lesions. This review focuses on the molecular mechanisms behind ALL-associated JAK2 mutations and JAK2 fusion genes, known and potential causes of JAK-inhibitor resistance, and how JAK2 alterations could be targeted using alternative and novel rationally designed therapies to guide precision medicine approaches for these high-risk subtypes of ALL.

Expression of chronic myeloid leukemia oncogenes BCR-ABL P210 and BCR-ABL T315I affect cellular and humoral innate immunity in Drosophila melanogaster

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm that results from a chromosomal translocation between chromosome 9 and chromosome 22. The resulting fusion gene ( BCR-ABL ) encodes a constitutively active BCR-ABL tyrosine kinase. Some mutations of this oncogene, especially the Threonine 315 to Isoleucine substitution of the ABL kinase is resistant to first and second-generation tyrosine kinase inhibitors (TKIs) conventionally used in CML therapy. We have previously validated a CML fruit fly model for drug screening using the adult fly compound eye. Here we expressed wild-type BCR-ABL ^P210 and mutated BCR-ABL ^T315I in Drosophila melanogaster hematopoietic system to understand the phenotypic consequences of this expression and its impact on innate immune pathways. Flies expressing both wild-type BCR-ABL^P210 and mutant BCR-ABL^T315I showed increased number of circulating hemocytes, disruption in sessile patterning of resident hemocytes, dysregulation in the humoral Toll, ImD, and JAK/STAT pathways at the mRNA level in both the 3 ^rd instar larva and adult stages. Of note, BCR-ABL^T315I flies presented more severe phenotypes and a higher deviation in humoral dysregulation than BCR -ABL^P210 flies pointing towards more complex oncogenic effect of this mutant which requires further investigation.

Mechanistic Insights Into Co-Administration of Allosteric and Orthosteric Drugs to Overcome Drug-Resistance in T315I BCR-ABL1

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm, driven by the BCR-ABL1 fusion oncoprotein. The discovery of orthosteric BCR-ABL1 tyrosine kinase inhibitors (TKIs) targeting its active ATP-binding pocket, such as first-generation Imatinib and second-generation Nilotinib (NIL), has profoundly revolutionized the therapeutic landscape of CML. However, currently targeted therapeutics still face considerable challenges with the inevitable emergence of drug-resistant mutations within BCR-ABL1. One of the most common resistant mutations in BCR-ABL1 is the T315I gatekeeper mutation, which confers resistance to most current TKIs in use. To resolve such conundrum, co-administration of orthosteric TKIs and allosteric drugs offers a novel paradigm to tackle drug resistance. Remarkably, previous studies have confirmed that the dual targeting BCR-ABL1 utilizing orthosteric TKI NIL and allosteric inhibitor ABL001 resulted in eradication of the CML xenograft tumors, exhibiting promising therapeutic potential. Previous studies have demonstrated the cooperated mechanism of two drugs. However, the conformational landscapes of synergistic effects remain unclear, hampering future efforts in optimizations and improvements. Hence, extensive large-scale molecular dynamics (MD) simulations of wide type (WT), WT-NIL, T315I, T315I-NIL, T315I-ABL001 and T315I-ABL001-NIL systems were carried out in an attempt to address such question. Simulation data revealed that the dynamic landscape of NIL-bound BCR-ABL1 was significantly reshaped upon ABL001 binding, as it shifted from an active conformation towards an inactive conformation. The community network of allosteric signaling was analyzed to elucidate the atomistic overview of allosteric regulation within BCR-ABL1. Moreover, binding free energy analysis unveiled that the affinity of NIL to BCR-ABL1 increased by the induction of ABL001, which led to its favorable binding and the release of drug resistance. The findings uncovered the in-depth structural mechanisms underpinning dual-targeting towards T315I BCR-ABL1 to overcome its drug resistance and will offer guidance for the rational design of next generations of BCR-ABL1 modulators and future combinatory therapeutic regimens.

Genetic Biomarkers in Chronic Myeloid Leukemia: What Have We Learned So Far?

Chronic Myeloid Leukemia (CML) is a rare malignant proliferative disease of the hematopoietic system, whose molecular hallmark is the Philadelphia chromosome (Ph). The Ph chromosome originates an aberrant fusion gene with abnormal kinase activity, leading to the buildup of reactive oxygen species and genetic instability of relevance in disease progression. Several genetic abnormalities have been correlated with CML in the blast phase, including chromosomal aberrations and common altered genes. Some of these genes are involved in the regulation of cell apoptosis and proliferation, such as the epidermal growth factor receptor (EGFR), tumor protein p53 (TP53), or Schmidt-Ruppin A-2 proto-oncogene (SRC); cell adhesion, e.g., catenin beta 1 (CTNNB1); or genes associated to TGF-β, such as SKI like proto-oncogene (SKIL), transforming growth factor beta 1 (TGFB1) or transforming growth factor beta 2 (TGFB2); and TNF-α pathways, such as Tumor necrosis factor (TNFA) or Nuclear factor kappa B subunit 1 (NFKB1). The involvement of miRNAs in CML is also gaining momentum, where dysregulation of some critical miRNAs, such as miRNA-451 and miRNA-21, which have been associated to the molecular modulation of pathogenesis, progression of disease states, and response to therapeutics. In this review, the most relevant genomic alterations found in CML will be addressed.

Acquired JAK2 mutations confer resistance to JAK inhibitors in cell models of acute lymphoblastic leukemia

Ruxolitinib (rux) Phase II clinical trials are underway for the treatment of high-risk JAK2-rearranged (JAK2r) B-cell acute lymphoblastic leukemia (B-ALL). Treatment resistance to targeted inhibitors in other settings is common; elucidating potential mechanisms of rux resistance in JAK2r B-ALL will enable development of therapeutic strategies to overcome or avert resistance. We generated a murine pro-B cell model of ATF7IP-JAK2 with acquired resistance to multiple type-I JAK inhibitors. Resistance was associated with mutations within the JAK2 ATP/rux binding site, including a JAK2 p.G993A mutation. Using in vitro models of JAK2r B-ALL, JAK2 p.G993A conferred resistance to six type-I JAK inhibitors and the type-II JAK inhibitor, CHZ-868. Using computational modeling, we postulate that JAK2 p.G993A enabled JAK2 activation in the presence of drug binding through a unique resistance mechanism that modulates the mobility of the conserved JAK2 activation loop. This study highlights the importance of monitoring mutation emergence and may inform future drug design and the development of therapeutic strategies for this high-risk patient cohort.

Side-effects profile and outcomes of ponatinib in the treatment of chronic myeloid leukemia

Ponatinib is associated with cardiovascular adverse events (CAEs), and its frequency in the real world is limited. In this retrospective study, we examined the survival outcomes and associated toxicities in 78 consecutive ponatinib-treated patients with chronic myeloid leukemia (CML) at the Moffitt Cancer Center from January 2011 through December 2017. The most common non-CAE was thrombocytopenia (39.7%), occurring in a dose-dependent fashion. Eighteen patients (23.1%) experienced some form of CAE, with the most common being arrhythmia (9%) and hypertension (7.7%), whereas 3 patients experienced myocardial infarction (3.8%). Before 2014, most patients were started on ponatinib 45 mg daily. There was an inverse correlation between cardio-oncology referral and the number of CAEs (P = .0440); however, a lower ponatinib starting dose, more frequent dose reduction, and increased cardio-oncology referral all were likely to have contributed to the observed decrease in CAEs after 2014. The response rate and 5-year overall survival (OS) were higher than those observed in the Ponatinib Ph+ ALL and CML Evaluation (PACE) trial (major molecular response, 58.7% vs 40% and OS, 76% vs 73%; median follow-up of 32.5 months). Ponatinib-treated patients with chronic phase-CML did not show a significant improvement with allogeneic stem cell transplantation, whereas those with accelerated phase/blast phase-CML had a much better outcome (median OS of 32.9 months vs 9.2 months; P = .01). These results demonstrate that ponatinib is highly effective. Dose adjustments and increased awareness of the cardiotoxicities associated with ponatinib may help maximize its benefits.

Autophagic flux inhibition enhances cytotoxicity of the receptor tyrosine kinase inhibitor ponatinib

Background

Despite reported advances, acquired resistance to tyrosine kinase inhibitors still represents a serious problem in successful cancer treatment. Among this class of drugs, ponatinib (PON) has been shown to have notable long-term efficacy, although its cytotoxicity might be hampered by autophagy. In this study, we examined the likelihood of PON resistance evolution in neuroblastoma and assessed the extent to which autophagy might provide survival advantages to tumor cells.

Methods

The effects of PON in inducing autophagy were determined both in vitro, using SK-N-BE(2), SH-SY5Y, and IMR-32 human neuroblastoma cell lines, and in vivo, using zebrafish and mouse models. Single and combined treatments with chloroquine (CQ)—a blocking agent of lysosomal metabolism and autophagic flux—and PON were conducted, and the effects on cell viability were determined using metabolic and immunohistochemical assays. The activation of the autophagic flux was analyzed through immunoblot and protein arrays, immunofluorescence, and transmission electron microscopy. Combination therapy with PON and CQ was tested in a clinically relevant neuroblastoma mouse model.

Results

Our results confirm that, in neuroblastoma cells and wild-type zebrafish embryos, PON induces the accumulation of autophagy vesicles—a sign of autophagy activation. Inhibition of autophagic flux by CQ restores the cytotoxic potential of PON, thus attributing to autophagy a cytoprotective nature. In mice, the use of CQ as adjuvant therapy significantly improves the anti-tumor effects obtained by PON, leading to ulterior reduction of tumor masses.

Conclusions

Together, these findings support the importance of autophagy monitoring in the treatment protocols that foresee PON administration, as this may predict drug resistance acquisition. The findings also establish the potential for combined use of CQ and PON, paving the way for their consideration in upcoming treatment protocols against neuroblastoma.

Philadelphia Chromosome-Positive Leukemia in the Lymphoid Lineage-Similarities and Differences with the Myeloid Lineage and Specific Vulnerabilities

Philadelphia chromosome (Ph) results from a translocation between the breakpoint cluster region (BCR) gene on chromosome 9 and ABL proto-oncogene 1 (ABL1) gene on chromosome 22. The fusion gene, BCR-ABL1, is a constitutively active tyrosine kinase which promotes development of leukemia. Depending on the breakpoint site within the BCR gene, different isoforms of BCR-ABL1 exist, with p210 and p190 being the most prevalent. P210 isoform is the hallmark of chronic myeloid leukemia (CML), while p190 isoform is expressed in majority of Ph-positive B cell acute lymphoblastic leukemia (Ph+ B-ALL) cases. The crucial component of treatment protocols of CML and Ph+ B-ALL patients are tyrosine kinase inhibitors (TKIs), drugs which target both BCR-ABL1 isoforms. While TKIs therapy is successful in great majority of CML patients, Ph+ B-ALL often relapses as a drug-resistant disease. Recently, the high-throughput genomic and proteomic analyses revealed significant differences between CML and Ph+ B-ALL. In this review we summarize recent discoveries related to differential signaling pathways mediated by different BCR-ABL1 isoforms, lineage-specific genetic lesions, and metabolic reprogramming. In particular, we emphasize the features distinguishing Ph+ B-ALL from CML and focus on potential therapeutic approaches exploiting those characteristics, which could improve the treatment of Ph+ B-ALL.

Mutations in the BCR-ABL1 kinase domain in patients with chronic myeloid leukaemia treated with TKIs or at diagnosis

The aim of the present study was to analyse the incidence of mutations in the BCR-ABL1 kinase region in patients with newly diagnosed or treated chronic myeloid leukaemia (CML), and the association between mutations clinicopathological characteristics. Samples were collected for mutation analysis from patients who exhibited tyrosine kinase inhibitor resistance following treatment or were in the accelerated or blast phase at diagnosis. The mutations in the breakpoint cluster region (BCR)-ABL proto-oncogene 1 (ABL1) kinase domain were evaluated using conventional sequencing or ultra-deep sequencing (UDS) of peripheral blood samples. Sanger sequencing and UDS of the cDNA region corresponding to the BCR-ABL1 kinase domain was performed. χ² test was used to assess the association of categorical variables between the mutated and non-mutated groups. In addition, the Kaplan-Meier method was applied to generate the survival curves. Sequencing detected 28 different mutations in 54 of the 175 (30.86%) patients with CML. A total of 14 (8.0%) patients presented with the T315I mutation, accounting for the largest proportion in the mutated group. Eight patients (4.6%) presented with more than one mutation, three (37.5%) of whom harboured T315I coexisting with other mutations, and for nine (5.1%) patients, the results differed between conventional sequencing and UDS, with the mutations being missed by conventional sequencing. The results form this study suggested that programing mutation analysis in patients with chronic myeloid leukaemia timely may guide the choice of TKIs.

The Role of Biomarkers in Cardio-Oncology

In the field of cardio-oncology, it is well recognised that despite the benefits of chemotherapy in treating and possibly curing cancer, it can cause catastrophic damage to bystander tissues resulting in a range of potentially of life-threatening cardiovascular toxicities, and leading to a number of damaging side effects including heart failure and myocardial infarction. Cardiotoxicity is responsible for significant morbidity and mortality in the long-term in oncology patients, specifically due to left ventricular dysfunction. There is increasing emphasis on the early use of biomarkers in order to detect the cardiotoxicity at a stage before it becomes irreversible. The most important markers of cardiac injury are cardiac troponin and natriuretic peptides, whilst markers of inflammation such as interleukin-6, C-reactive protein, myeloperoxidase, Galectin-3, growth differentiation factor-15 are under investigation for their use in detecting cardiotoxicity early. In addition, microRNAs, genome-wide association studies and proteomics are being studied as novel markers of cardiovascular injury or inflammation. The aim of this literature review is to discuss the evidence base behind the use of these biomarkers for the detection of cardiotoxicity.

Landscape of drug-resistance mutations in kinase regulatory hotspots

More than 48 kinase inhibitors (KIs) have been approved by Food and Drug Administration. However, drug-resistance (DR) eventually occurs, and secondary mutations have been found in the previously targeted primary-mutated cancer cells. Cancer and drug research communities recognize the importance of the kinase domain (KD) mutations for kinasopathies. So far, a systematic investigation of kinase mutations on DR hotspots has not been done yet. In this study, we systematically investigated four types of representative mutation hotspots (gatekeeper, G-loop, αC-helix and A-loop) associated with DR in 538 human protein kinases using large-scale cancer data sets (TCGA, ICGC, COSMIC and GDSC). Our results revealed 358 kinases harboring 3318 mutations that covered 702 drug resistance hotspot residues. Among them, 197 kinases had multiple genetic variants on each residue. We further computationally assessed and validated the epidermal growth factor receptor mutations on protein structure and drug-binding efficacy. This is the first study to provide a landscape view of DR-associated mutation hotspots in kinase's secondary structures, and its knowledge will help the development of effective next-generation KIs for better precision medicine.

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.

Management of a 75-Year-Old Lady with Refractory Chronic Myelogenous Leukemia

Chronic myelogenous leukemia (CML) is a hematopoietic disorder caused by the BCR/ABL gene or Philadelphia chromosome. The first Food and Drug Administration (FDA)-approved tyrosine kinase inhibitor for treatment of CML was imatinib in 2001. Since then, multiple therapies, such as nilotinib, dasatinib, bosutinib, and, more recently, ponatinib, have made their way as viable treatment options for first-line and secondary therapies. Most patients tend to respond to first-line treatment. Although there is a subset of patients who do not achieve complete molecular response with first line, newer options have proven beneficial. As we progress through therapies, there still remain some patients who do not adequately respond to current available therapies. The treatment options and guidelines become more difficult in such situations, not only with respect to cost but also patient quality of life and satisfaction. We discuss a 75-year-old white female with CML, who has had multiple therapies with hematological remission but has never achieved complete molecular remission, currently on bosutinib and tolerating it well.

The effects of combination treatments on drug resistance in chronic myeloid leukaemia: an evaluation of the tyrosine kinase inhibitors axitinib and asciminib

BACKGROUND

Chronic myeloid leukaemia is in principle a treatable malignancy but drug resistance is lowering survival. Recent drug discoveries have opened up new options for drug combinations, which is a concept used in other areas for preventing drug resistance. Two of these are (I) Axitinib, which inhibits the T315I mutation of BCR-ABL1, a main source of drug resistance, and (II) Asciminib, which has been developed as an allosteric BCR-ABL1 inhibitor, targeting an entirely different binding site, and as such does not compete for binding with other drugs. These drugs offer new treatment options.

METHODS

We measured the proliferation of KCL-22 cells exposed to imatinib-dasatinib, imatinib-asciminib and dasatinib-asciminib combinations and calculated combination index graphs for each case. Moreover, using the median-effect equation we calculated how much axitinib can reduce the growth advantage of T315I mutant clones in combination with available drugs. In addition, we calculated how much the total drug burden could be reduced by combinations using asciminib and other drugs, and evaluated which mutations such combinations might be sensitive to.

RESULTS

Asciminib had synergistic interactions with imatinib or dasatinib in KCL-22 cells at high degrees of inhibition. Interestingly, some antagonism between asciminib and the other drugs was present at lower degrees on inhibition. Simulations revealed that asciminib may allow for dose reductions, and its complementary resistance profile could reduce the risk of mutation based resistance. Axitinib, however, had only a minor effect on T315I growth advantage.

CONCLUSIONS

Given how asciminib combinations were synergistic in vitro, our modelling suggests that drug combinations involving asciminib should allow for lower total drug doses, and may result in a reduced spectrum of observed resistance mutations. On the other hand, a combination involving axitinib was not shown to be useful in countering drug resistance.

A Chemical Approach to Overcome Tyrosine Kinase Inhibitors Resistance: Learning from Chronic Myeloid Leukemia

BACKGROUND

The possibilities of treatment for oncological diseases are growing enormously in the last decades. Unfortunately, these developments have led to the onset of resistances with regards to the new treatments. This is particularly true if we face with the therapeutic field of Tyrosine Kinase Inhibitors (TKIs). This review gives an overview of possible TKI resistances that can occur during the treatment of an oncologic diesease and available strategies that can be adopted, taking cues from a successful example such as CML.

METHODS

We performed a literature search for peer-reviewed articles using different databases, such as PubMed and Scopus, and exploiting different keywords and different logical operators.

RESULTS

68 papers were included in the review. Twenty-four papers give an overview of the causes of TKIs resistances in the wide oncologic field. The remaining papers deal CML, deeply analysing the TKIs Resistances present in this pathology and the strategies adopted to overcome them.

CONCLUSION

The aim of this review is to furnish an overview and a methodological guideline for the approach and the overcoming of TKIs Resistances.

Cardiac Complications in the Adult Bone Marrow Transplant Patient

PURPOSE OF REVIEW

Due to advancements in oncologic treatment strategies and techniques, the number of survivors who have undergone hematopoetic stem cell transplant (HCT) continues to increase in the United States; this number is projected to reach 502,000 by the year 2030. There is significant interest within the field of cardio-oncology to identify cardiotoxicity and cardiovascular disease in the HCT population. Epidemiologic studies analyzing both short- and long-term cardiovascular effects, risk stratification modeling, cardioprotective strategies, and expert consensus documents for cardiotoxicity surveillance recommendations are reviewed.

RECENT FINDINGS

Patients who have undergone HCT are at increased risk of cardiovascular events and mortality compared to matched controls. The type of cardiotoxicity and the incidence rates vary based on specific therapeutic regimens and pre-existing cardiovascular risk factors. Life-threatening cardiotoxicity can present during HCT as acute heart failure, arrhythmias, pericardial tamponade, or cardiac arrest; or it can present late after treatment as cardiomyopathy, ischemic heart disease, vascular disease, stroke, or comorbid conditions, such as hypertension and diabetes mellitus that are associated with cardiac events. HCT is associated with excess cardiovascular risk partially due to exposure to cardiotoxic chemotherapy and radiation, as well as indirect and direct detrimental effects on cardiovascular reserve. This review discusses the epidemiology and the known cardiotoxic effects of historical chemoradiation agents in addition to newer targeted therapies. Recent expert consensus statements from cardiology and hematology/oncology societies are reviewed in regard to risk stratification of the cancer patient based on the type of treatments. Finally, gaps in knowledge are identified with proposed avenues of research that will allow for more accurate risk assessment, prediction, and potential treatment of the HCT patient in attenuating the risk of developing both short- and long-term cardiovascular comorbidities.

Insights into the optimal use of ponatinib in patients with chronic phase chronic myeloid leukaemia

There are five tyrosine kinase inhibitors (TKIs) that are currently approved (in the European Union and the United States) for the treatment of chronic myeloid leukaemia (CML) in the chronic phase (CP) and each of them has its own efficacy and toxicity profile. Oral ponatinib (Iclusig^®) is a third-generation TKI structurally designed to inhibit native BCR-ABL1 tyrosine kinase and several BCR-ABL1 mutants, including T315I. Ponatinib is now approved for patients with CML who are resistant or intolerant to prior TKI therapy (European Union) or for whom no other TKI therapy is indicated (United States). Despite achieving results in heavily treated patients, which led to its approval, the drug may induce cardiovascular events, requiring a careful baseline assessment of predisposing risk factors and specific management during treatment. Pharmacokinetic analysis has indicated the possibility of reducing the starting dose of ponatinib to 15 mg/day and preliminary data showed advantages in terms of safety while maintained its efficacy. This review summarizes the results achieved and drug-related side effects reported in all clinical trials and real-life experiences, testing ponatinib in patients with CP-CML. In addition, we focus on the appropriate use of ponatinib in clinical practice suggesting some useful recommendations on the proper management of this drug.

Mutations in the breakpoint cluster region-Abelson murine leukemia 1 gene in Brazilian patients with chronic myeloid leukemia

Introduction

Mutations in the breakpoint cluster region-Abelson murine leukemia 1 gene are the leading cause of resistance to treatment with tyrosine kinase inhibitors in chronic myeloid leukemia patients. Mutations have been detected throughout the extension of the kinase domain of this gene and it is important to investigate their positions because there may be a difference in clinical relevance.

Objective

To evaluate mutations in the transcripts of the BCR-ABL1 gene in Brazilian patients with chronic myeloid leukemia under tyrosine kinase inhibitor treatment in the Hospital de Clínicas of the Universidade Federal do Paraná.

Methods

This retrospective observational cross-sectional study analyzed mutation data of BCR-ABL1 gene transcripts. Three hundred and thirty peripheral blood samples from 193 patients were evaluated with the search for mutations being achieved by Sanger sequencing.

Results

Sixteen mutation types were identified in 48/193 (24.87%) patients with T315I (20.83%) being the most common. Furthermore, four polymorphisms (T240T, K247R, E275E and Y275Y) were identified. The highest incidence of mutations (19/53: 35.85%) occurred in the P-loop of the tyrosine kinase domain, whereas no mutation was found in the A-loop. In 43/48 (89.58%) patients only one mutation was found and more than one mutation was found in 5/48 (10.42%). The simultaneous presence of two mutations (E189G/V299L and E255K/T315I) was observed in 2/5 patients while the different mutations were seen in sequential samples of the other three patients (Y253Y/T315I, T315I/E255K and E255K/T315I).

Conclusions

This molecular characterization contributed to the identification of the resistance profile to tyrosine kinase inhibitors in Brazilian patients, thus enabling the use of adequate therapeutic strategies in a timely manner.

Ponatinib Activates an Inflammatory Response in Endothelial Cells via ERK5 SUMOylation

Ponatinib is a multi-targeted third generation tyrosine kinase inhibitor (TKI) used in the treatment of chronic myeloid leukemia (CML) patients harboring the Abelson (Abl)-breakpoint cluster region (Bcr) T315I mutation. In spite of having superb clinical efficacy, ponatinib triggers severe vascular adverse events (VAEs) that significantly limit its therapeutic potential. On vascular endothelial cells (ECs), ponatinib promotes EC dysfunction and apoptosis, and inhibits angiogenesis. Furthermore, ponatinib-mediated anti-angiogenic effect has been suggested to play a partial role in systemic and pulmonary hypertension via inhibition of vascular endothelial growth factor receptor 2 (VEGFR2). Even though ponatinib-associated VAEs are well documented, their etiology remains largely unknown, making it difficult to efficiently counteract treatment-related adversities. Therefore, a better understanding of the mechanisms by which ponatinib mediates VAEs is critical. In cultured human aortic ECs (HAECs) treated with ponatinib, we found an increase in nuclear factor NF-kB/p65 phosphorylation and NF-kB activity, inflammatory gene expression, cell permeability, and cell apoptosis. Mechanistically, ponatinib abolished extracellular signal-regulated kinase 5 (ERK5) transcriptional activity even under activation by its upstream kinase mitogen-activated protein kinase kinase 5α (CA-MEK5α). Ponatinib also diminished expression of ERK5 responsive genes such as Krüppel-like Factor 2/4 (klf2/4) and eNOS. Because ERK5 SUMOylation counteracts its transcriptional activity, we examined the effect of ponatinib on ERK5 SUMOylation, and found that ERK5 SUMOylation is increased by ponatinib. We also found that ponatibib-mediated increased inflammatory gene expression and decreased anti-inflammatory gene expression were reversed when ERK5 SUMOylation was inhibited endogenously or exogenously. Overall, we propose a novel mechanism by which ponatinib up-regulates endothelial ERK5 SUMOylation and shifts ECs to an inflammatory phenotype, disrupting vascular homeostasis.

Targeted therapy for fusion-driven high-risk acute leukemia

Despite continued progress in drug development for acute leukemias, outcomes for patients with some subtypes have not changed significantly in the last decade. Recurrent chromosomal translocations have long been recognized as driver events in leukemia, and many of these oncogenic fusions portend high-risk disease. Improved understanding of the molecular underpinnings of these fusions, coupled with novel chemistry approaches, now provide new opportunity for therapeutic inroads into the treatment of leukemia driven by these fusions.

Alkynylnicotinamide-Based Compounds as ABL1 Inhibitors with Potent Activities against Drug-Resistant CML Harboring ABL1(T315I) Mutant Kinase

The introduction of imatinib into the clinical scene revolutionized the treatment of chronic myelogenous leukemia (CML). The overall eight-year survival rate for CML has increased from about 6 % in the 1970s to over 90 % in the imatinib era. However, about 20 % of CML patients harbor primary or acquired resistance to tyrosine kinase inhibitors. ABL1 point mutations in the BCR-ABL1 fusion protein, such as ABL1(T315I), typically emerge after prolonged kinase inhibitor treatment. Ponatinib (AP24534) is currently the only approved CML drug that is active against the ABL1(T315I) mutation. However, ponatinib has severe cardiovascular toxicities; hence, there have been efforts to find safer CML drugs that work against ABL1 secondary mutations. We reveal that isoquinoline- or naphthyridine-based compounds, such as HSN431, HSN576, HSN459, and HSN608 potently inhibit the enzymatic activities of ABL1, ABL1(T315I), and ABL1(E255K). These compounds inhibit the proliferation of ABL1-driven CML cell lines, K652 and KCL22 as well as the drug-resistant cell line, KCL22-IR, which harbors the secondary mutated ABL1(T315I) kinase.

Hitting two oncogenic machineries in cancer cells: cooperative effects of the multi-kinase inhibitor ponatinib and the BET bromodomain blockers JQ1 or dBET1 on human carcinoma cells

In recent years, numerous new targeted drugs, including multi-kinase inhibitors and epigenetic modulators have been developed for cancer treatment. Ponatinib blocks a variety of tyrosine kinases including ABL and fibroblast growth factor receptor (FGFR), and the BET bromodomain (BRD) antagonists JQ1 and dBET1 impede MYC oncogene expression. Both drugs have demonstrated substantial anti-cancer efficacy against several hematological malignancies. Solid tumors, on the other hand, although frequently driven by FGFR and/or MYC, are often unresponsive to these drugs. This is due, at least in part, to compensatory feedback-loops in the kinome and transcription network of these tumors, which are activated in response to drug exposure. Therefore, we hypothesized that the combination of the multi-kinase inhibitor ponatinib with transcription modulators such as JQ1 or dBET1 might overcome this therapeutic recalcitrance. Using ³H-thymidine uptake, cell cycle analysis, and caspase-3 or Annexin V labeling, we demonstrate that single drugs induce moderate dose-dependent growth-inhibition and/or apoptosis in colon (HCT116, HT29), breast (MCF-7, SKBR3) and ovarian (A2780, SKOV3) cancer cells. Ponatinib elicited primarily apoptosis, while JQ1 and dBET1 caused G0/G1 cell cycle arrest and very mild cell death. Phospho-FGFR and MYC, major targets of ponatinib and BET inhibitors, were downregulated after treatment with single drugs. Remarkably, ponatinib was found to sensitize cells to BET antagonists by enhancing apoptotic cell death, and this effect was associated with downregulation of MYC. In summary, our data shows that ponatinib sensitizes colon, breast, and ovarian cancer cells to BET bromodomain inhibitors. Further studies are warranted to determine the clinical value of this phenomenon.

HDAC1,2 inhibition and doxorubicin impair Mre11-dependent DNA repair and DISC to override BCR-ABL1-driven DSB repair in Philadelphia chromosome-positive B-cell precursor acute lymphoblastic leukemia

Philadelphia chromosome-positive (Ph+) B-cell precursor acute lymphoblastic leukemia (ALL) expressing BCR-ABL1 oncoprotein is a major subclass of ALL with poor prognosis. BCR-ABL1-expressing leukemic cells are highly dependent on double-strand break (DSB) repair signals for their survival. Here we report that a first-in-class HDAC1,2 selective inhibitor and doxorubicin (a hyper-CVAD chemotherapy regimen component) impair DSB repair networks in Ph+ B-cell precursor ALL cells using common as well as distinct mechanisms. The HDAC1,2 inhibitor but not doxorubicin alters nucleosomal occupancy to impact chromatin structure, as revealed by MNase-Seq. Quantitative mass spectrometry of the chromatin proteome along with functional assays showed that the HDAC1,2 inhibitor and doxorubicin either alone or in combination impair the central hub of DNA repair, the Mre11-Rad51-DNA ligase 1 axis, involved in BCR-ABL1-specific DSB repair signaling in Ph+ B-cell precursor ALL cells. HDAC1,2 inhibitor and doxorubicin interfere with DISC (DNA damage-induced transcriptional silencing in cis)) or transcriptional silencing program in cis around DSB sites via chromatin remodeler-dependent and -independent mechanisms, respectively, to further impair DSB repair. HDAC1,2 inhibitor either alone or when combined with doxorubicin decreases leukemia burden in vivo in refractory Ph+ B-cell precursor ALL patient-derived xenograft mouse models. Overall, our novel mechanistic and preclinical studies together demonstrate that HDAC1,2 selective inhibition can overcome DSB repair 'addiction' and provide an effective therapeutic option for Ph+ B-cell precursor ALL.

Spotlight on ponatinib in the treatment of chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia: patient selection and perspectives

Ponatinib, a third-generation tyrosine kinase inhibitor that inhibits BCR/ABL independent of the mutation status, is currently approved for the treatment of patients with chronic myeloid leukemia or acute lymphoblastic leukemia that are either resistant or unable to tolerate another tyrosine kinase inhibitor. Its US Food and Drug Administration approval was based on results from long-term follow-up of the pivotal Phase II PACE trial, which demonstrated deep and durable molecular responses in the treated patients. Despite the remarkable responses, ponatinib has been associated with high frequency of severe vascular events, which led to its withdrawal from the market in 2013. Following analysis of the risk factors of patients who developed vascular side effects, ponatinib was reintroduced in the market 1 year later with specific dose-reduction recommendations and carrying a black box warning. Thus, careful patient selection with identification of patients whose potential benefit from ponatinib exceeds the potential risks associated with its use is crucial. Ongoing and future studies are focusing on earlier detection of mutations, strategies to minimize side effects, and potential expansion of the treatment indications. Clinical trials testing the safety and efficacy of ponatinib as frontline therapy are ongoing.

4-Nerolidylcatechol: apoptosis by mitochondrial mechanisms with reduction in cyclin D1 at G0/G1 stage of the chronic myelogenous K562 cell line

CONTEXT

4-Nerolidylcatechol (4-NRC) has showed antitumor potential through apoptosis. However, its apoptotic mechanisms are still unclear, especially in leukemic cells.

OBJECTIVES

To evaluate the cytotoxic potential of 4-NRC and its cell death pathways in p53-null K562 leukemic cells.

MATERIALS AND METHODS

Cytotoxicity of 4-NRC (4.17-534.5 μM) over 24 h of exposure was evaluated by MTT assay. 4-NRC-induced apoptosis in K562 cells was investigated by phosphatidylserine (PS) externalization, cell cycle, sub-G1, mitochondrial evaluation, cytochrome c, cyclin D1 and intracellular reactive oxygen species (ROS) levels, and caspase activity analysis.

RESULTS

IC50 values obtained were 11.40, 27.31, 15.93 and 15.70 μM for lymphocytes, K562, HL-60 and Jurkat cells, respectively. In K562 cells, 4-NRC (27 μM) promoted apoptosis as verified by cellular morphological changes, a significant increase in PS externalization and sub-G1 cells. Moreover, it significantly arrested the cells at the G0/G1 phase due to a reduction in cyclin D1 expression. These effects of 4-NRC also significantly promoted a reduction in mitochondrial activity and membrane depolarization, accumulation of cytosolic cytochrome c and ROS overproduction. Additionally, it triggered an increase in caspases -3/7, -8 and -9 activities. When the cells were pretreated with N-acetyl-l-cysteine ROS scavenger, 4-NRC-induced apoptosis was partially blocked, which suggests that it exerts cytotoxicity though not exclusively through ROS-mediated mechanisms.

DISCUSSION AND CONCLUSION

4-NRC has antileukemic properties, inducing apoptosis mediated by mitochondrial-dependent mechanisms with cyclin D1 inhibition. Given that emerging treatment concepts include novel combinations of well-known agents, 4-NRC could offer a promising alternative for chemotherapeutic combinations to maximize tumour suppression.

Combination of Emricasan with Ponatinib Synergistically Reduces Ischemia/Reperfusion Injury in Rat Brain Through Simultaneous Prevention of Apoptosis and Necroptosis

Apoptosis and receptor-interacting protein kinase 1/3(RIPK1/3)-mediated necroptosis contribute to the cerebral ischemia/reperfusion (I/R) injury. Emricasan is an inhibitor of caspases in clinical trials for liver diseases while ponatinib could be a potential inhibitor for RIPK1/3. This study aims to investigate the effect of emricasan and/or ponatinib on cerebral I/R injury and the underlying mechanisms. Firstly, we evaluated the status of apoptosis and necroposis in a rat model of cerebral I/R under different conditions, which showed noticeable apoptosis and necroptosis under condition of 2-h ischemia and 24-h reperfusion; next, the preventive or therapeutic effect of emricasan or ponatinib on cerebral I/R injury was tested. Administration of emricasan or ponatinib either before or after ischemia could decrease the neurological deficit score and infarct volume; finally, the combined therapeutic effect of emricasan with ponatinib on I/R injury was examined. Combined application of emricasan and ponatinib could further decrease the I/R injury compared to single application. Emricasan decreased the activities of capase-8/-3 in the I/R-treated brain but not the protein levels of necroptosis-relevant proteins: RIPK1, RIPK3, and mixed lineage kinase domain-like (MLKL), whereas ponatinib suppressed the expressions of these proteins but not the activities of capase-8/-3. Combination of emricasan with ponatinib could suppress both capase-8/-3 and necroptosis-relevant proteins. Based on these observations, we conclude that combination of emricasan with ponatinib could synergistically reduce I/R injury in rat brain through simultaneous prevention of apoptosis and necroptosis. Our findings might lay a basis on extension of the clinical indications for emricasan and ponatinib in treating ischemic stroke.

Novel Pathways of Ponatinib Disposition Catalyzed By CYP1A1 Involving Generation of Potentially Toxic Metabolites

Ponatinib, a pan-BCR-ABL tyrosine kinase inhibitor for the treatment of chronic myeloid leukemia (CML), causes severe side effects including vascular occlusions, pancreatitis, and liver toxicity, although the underlying mechanisms remain unclear. Modifications of critical proteins through reactive metabolites are thought to be responsible for a number of adverse drug reactions. In vitro metabolite screening of ponatinib with human liver microsomes and glutathione revealed unambiguous signals of ponatinib-glutathione (P-GSH) adducts. Further profiling of human cytochrome P450 (P450) indicated that CYP1A1 was the predominant P450 enzyme driving this reaction. P-GSH conjugate formation paralleled the disappearance of hydroxylated ponatinib metabolites, suggesting the initial reaction was epoxide generation. Mouse glutathione S-transferase p1 (mGstp1) further enhanced P-GSH adduct formation in vitro. Ponatinib pharmacokinetics were determined in vivo in wild-type (WT) mice and mice humanized for CYP1A1/2 and treated with the CYP1A1 inducers 2,3,7,8-tetrachlorodibenzodioxin or 3-methylcholanthrene. Ponatinib exposure was significantly decreased in treated mice compared with controls (7.7- and 2.2-fold for WT and humanized CYP1A1/2, respectively). Interestingly, the P-GSH conjugate was only found in the feces of CYP1A1-induced mice, but not in control animals. Protein adducts were also identified by liquid chromatography-tandem mass spectrometry analysis of mGstp1 tryptic digests. These results indicate that not only could CYP1A1 be involved in ponatinib disposition, which has not been previously reported, but also that electrophilic intermediates resulting from CYP1A1 metabolism in normal tissues may contribute to ponatinib toxicity. These data are consistent with a recent report that CML patients who smoke are at greater risk of disease progression and premature death.

Characteristics and mutation analysis of Ph-positive leukemia patients with T315I mutation receiving tyrosine kinase inhibitors

Background

TKIs are the first-line treatment for patients with Ph-positive (Ph+) leukemia. However, drug resistance is frequently observed, mainly due to mutations within the breakpoint cluster region-Abelson leukemia virus (BCR-ABL) kinase domain. The T315I substitution confers complete resistance to TKIs. The aim of this study was to analyze the clinical characteristics of 17 patients with T315I mutation after TKI treatment and provide a basis for prognosis.

Patients and methods

The clinical data of 17 TKI-resistant Ph+ leukemia patients who were found to have a ABL kinase domain mutation from September 2008 to January 2017 were collected. Karyotypes and BCR-ABL fusion gene were analyzed by R-banding and fluorescence in situ hybridization, respectively. Total RNA was extracted by TRIzol reagent, and the ABL kinase domain mutation was detected by direct sequencing.

Results

A total of 17 patients reached effective remission including major molecular response and complete cytogenetic response. However, all the patients subsequently developed a T315I mutation after treatment with TKIs. The rate of the BCR-ABL fusion gene in most of the patients who developed the T315I mutation was significantly higher than that before the mutation. At initial diagnosis, patients average platelet count was 149.7×10⁹/L, whereas the average platelet count was only 53.88×10⁹/L after the T315I mutation (P<0.01). The results also showed that the survival time of patients with a high proportion of blast cells or a high number of white blood cells was obviously shortened.

Conclusion

Patients platelet count decreased when detected with the T315I mutation compared with the initial diagnosis. Combined use of different TKIs and complex chromosomal karyotypes may promote the development of the T315I mutation. When the ratio of blast cells was >50% and the number of white blood cells was >20×10⁹/L, poor survival prognosis was observed.

Sorafenib inhibits therapeutic induction of necroptosis in acute leukemia cells

Induction of necroptosis has emerged as an alternative approach to trigger programmed cell death, in particular in apoptosis-resistant cancer cells. Recent evidence suggests that kinase inhibitors targeting oncogenic B-RAF can also affect Receptor-interacting serine/threonine-protein kinase (RIP)1 and RIP3. Sorafenib, a multi-targeting kinase inhibitor with activity against B-RAF, is used for the treatment of acute leukemia. In the present study, we therefore investigated whether Sorafenib interferes with therapeutic induction of necroptosis in acute leukemia. Here, we report that Sorafenib inhibits necroptotic signaling and cell death in two models of necroptosis in acute leukemia. Sorafenib significantly reduces Second mitochondria-derived activator of caspases (Smac) mimetic-induced necroptosis in apoptosis-resistant acute myeloid leukemia (AML) cells as well as Smac mimetic/Tumor Necrosis Factor (TNF)α-induced necroptosis in FADD-deficient acute lymphoblastic leukemia (ALL) cells. Sub- to low micromolar concentrations of Sorafenib corresponding to its plasma levels reported in cancer patients are sufficient to inhibit necroptosis, emphasizing the clinical relevance of our findings. Furthermore, Sorafenib blocks Smac mimetic-mediated phosphorylation of mixed-lineage kinase domain-like protein (MLKL) that marks its activation, indicating that Sorafenib targets components upstream of MLKL such as RIP1 and RIP3. Intriguingly, Sorafenib reduces the Smac mimetic/TNFα-stimulated interaction of RIP1 with RIP3 and MLKL, demonstrating that it interferes with the assembly of the necrosome complex. Importantly, Sorafenib significantly protects primary, patient-derived AML blasts from Smac mimetic-induced necroptosis. By demonstrating that Sorafenib limits the anti-leukemic activity of necroptosis-inducing drugs in acute leukemia cells, our study has important implications for the use of Sorafenib in the treatment of acute leukemia.

Data driven polypharmacological drug design for lung cancer: analyses for targeting ALK, MET, and EGFR

Drug design of protein kinase inhibitors is now greatly enabled by thousands of publicly available X-ray structures, extensive ligand binding data, and optimized scaffolds coming off patent. The extensive data begin to enable design against a spectrum of targets (polypharmacology); however, the data also reveal heterogeneities of structure, subtleties of chemical interactions, and apparent inconsistencies between diverse data types. As a result, incorporation of all relevant data requires expert choices to combine computational and informatics methods, along with human insight. Here we consider polypharmacological targeting of protein kinases ALK, MET, and EGFR (and its drug resistant mutant T790M) in non small cell lung cancer as an example. Both EGFR and ALK represent sources of primary oncogenic lesions, while drug resistance arises from MET amplification and EGFR mutation. A drug which inhibits these targets will expand relevant patient populations and forestall drug resistance. Crizotinib co-targets ALK and MET. Analysis of the crystal structures reveals few shared interaction types, highlighting proton-arene and key CH–O hydrogen bonding interactions. These are not typically encoded into molecular mechanics force fields. Cheminformatics analyses of binding data show EGFR to be dissimilar to ALK and MET, but its structure shows how it may be co-targeted with the addition of a covalent trap. This suggests a strategy for the design of a focussed chemical library based on a pan-kinome scaffold. Tests of model compounds show these to be compatible with the goal of ALK, MET, and EGFR polypharmacology.

Tyrosine kinase inhibitors: potential use and safety considerations in HIV-1 infection

INTRODUCTION

Infection caused by HIV-1 is nowadays a chronic disease due to a highly efficient antiretroviral treatment that is nevertheless, unable to eliminate the virus from the organism. New strategies are necessary in order to impede the formation of the viral reservoirs, responsible for the failure of the antiretroviral treatment to cure the infection. Areas covered: The purpose of this review is to discuss the possibility of using tyrosine kinase inhibitors (TKIs) for the treatment of HIV-1 infection. These inhibitors are successfully used in patients with distinct cancers such as chronic myeloid leukemia. The most relevant papers have been selected and commented. Expert opinion: The family of TKIs are directed against the activation of tyrosine kinases from the Src family. Some of these kinases are essential for the activation of CD4 + T cells, the major target of HIV-1. During acute or primary infection the CD4 + T cells are massively activated, which is mostly responsible for the generation of the reservoirs, the spread of the infection and the destruction of activated CD4 + T cells, infected or not. Consequently, we discuss the possibility of using TKIs as adjuvant of the antiretroviral treatment against HIV-1 infection mostly, but not exclusively, during the acute/recent phase.

Overall survival with ponatinib versus allogeneic stem cell transplantation in Philadelphia chromosome-positive leukemias with the T315I mutation

BACKGROUND

Effective treatment options for patients with chronic myeloid leukemia (CML) or Philadelphia‐positive (Ph+) acute lymphoblastic leukemia (ALL) who have the threonine to isoleucine mutation at codon 315 (T315I) are few. The objective of this study was to compare overall survival (OS) between patients with CML and those with Ph+ ALL who received treatment with ponatinib versus allogeneic stem cell transplantation (allo‐SCT).

METHODS

A post hoc, retrospective, indirect comparison of OS among patients who received single‐agent ponatinib in the Ponatinib Ph+ ALL and CML Evaluation (PACE) trial with those who underwent allo‐SCT as reported to the European Bone Marrow Transplant registry, stratified by CML disease phase and Ph+ ALL, was conducted. Kaplan‐Meier survival curves and multivariate Cox proportional‐hazards models were used to compare OS between intervention groups, adjusting for time from diagnosis to intervention, age, sex, and geographic region; 24‐month and 48‐month OS rates and median OS were reported.

RESULTS

After adjustment for potential confounders, 24‐month and 48‐month OS rates were significantly higher in patients with chronic‐phase CML (CP‐CML) who received ponatinib compared with those who underwent allo‐SCT (24 months: 84% vs 60.5%, respectively; P = .004; 48 months: 72.7% vs 55.8%, respectively; P = .013), with a hazard ratio (HR) of 0.37 (95% confidence interval [CI], 0.16‐0.84; P = .017). In patients who had accelerated‐phase CML, OS rates were not significantly different between the groups (HR, 0.90; 95% CI, 0.20‐4.10; P = .889). In patients who had blast‐crisis CML and those with Ph+ ALL, ponatinib was associated with shorter OS compared with allo‐SCT (blast‐crisis CML: HR, 2.29 [95% CI, 1.08‐4.82; P = .030]; Ph+ ALL: HR, 2.77 [95% CI, 0.73‐10.56; P = .146]).

CONCLUSIONS

Although allo‐SCT remains an important treatment option for patients with T315I‐positive advanced CML and Ph+ ALL, ponatinib represents a valuable alternative for patients with T315I‐positive CP‐CML. Cancer 2017;123:2875–80. © 2017 American Cancer Society.

In patients who have chronic‐phase chronic myeloid leukemia (CML) with the Philadelphia chromosome threonine to isoleucine mutation at codon 315, single‐agent ponatinib is associated with significantly longer overall survival compared with allogenic stem cell transplantation. In those who have accelerated‐phase CML, blast‐crisis CML, and Philadelphia chromosome‐positive acute lymphoblastic leukemia with the T315I mutation, single‐agent ponatinib is associated with similar or shorter overall survival compared with stem cell transplantation.

Presence of novel compound BCR-ABL mutations in late chronic and advanced phase imatinib sensitive CML patients indicates their possible role in CML progression

BCR-ABL kinase domain (K_D) mutations are well known for causing resistance against tyrosine kinase inhibitors (TKIs) and disease progression in chronic myeloid leukemia (CML). In recent years, compound BCR-ABL mutations have emerged as a new threat to CML patients by causing higher degrees of resistance involving multiple TKIs, including ponatinib. However, there are limited reports about association of compound BCR-ABL mutations with disease progression in imatinib (IM) sensitive CML patients. Therefore, we investigated presence of ABL-K_D mutations in chronic phase (n = 41), late chronic phase (n = 33) and accelerated phase (n = 16) imatinib responders. Direct sequencing analysis was used for this purpose. Eleven patients (12.22%) in late-CP CML were detected having total 24 types of point mutations, out of which 8 (72.72%) harbored compound mutated sites. SH2 contact site mutations were dominant in our study cohort, with E355G (3.33%) being the most prevalent. Five patients (45%) all having compound mutated sites, progressed to advanced phases of disease during follow up studies. Two novel silent mutations G208G and E292E/E were detected in combination with other mutants, indicating limited tolerance for BCR-ABL1 kinase domain for missense mutations. However, no patient in early CP of disease manifested mutated ABL-K_D. Occurrence of mutations was found associated with elevated platelet count (p = 0.037) and patients of male sex (p = 0.049). The median overall survival and event free survival of CML patients (n = 90) was 6.98 and 5.8 y respectively. The compound missense mutations in BCR-ABL kinase domain responsible to elicit disease progression, drug resistance or disease relapse in CML, can be present in yet Imatinib sensitive patients. Disease progression observed here, emphasizes the need of ABL-K_D mutation screening in late chronic phase CML patients for improved clinical management of disease.

Ponatinib Induces a Persistent Molecular Response and Graft-versus-Host Disease/Graft-versus-Leukemia Effect in a Patient with Philadelphia-Positive Acute Lymphoblastic Leukemia with a T315I Mutation following Early Relapse after Allogeneic Transplant

We describe the case of a patient with a Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL) treated with dasatinib plus steroids as the first-line therapy who achieved a molecular complete remission and then underwent a matched, unrelated donor allogeneic transplant. Five months after the transplant, he experienced a disease relapse with an T315I mutation, which was resistant to salvage chemotherapy. Once the details of the T315I mutation were acquired, we initiated ponatinib treatment at a standard dosage and observed a rapid decrease of minimal residual disease (MRD) at molecular assessment. The bone marrow evaluation after 2, 3, 6, 10 and 13 months was negative for MRD. After starting ponatinib, the patient experienced a skin graft-versus-host disease (GVHD), whereas no occurrence of GVHD was observed after transplant, suggesting that the efficacy of ponatinib could be related not only to the direct antileukemic effect, but also to its ability to promote an indirect graft-versus-leukemia effect. Ponatinib was well tolerated but a thyroid dysfunction mimicking a cardiovascular toxicity was observed and solved with hormonal substitutive treatment.

The novel kinase inhibitor ponatinib is an effective anti-angiogenic agent against neuroblastoma

Background High-risk neuroblastoma has poor outcomes with high rates of relapse despite aggressive treatment, and novel therapies are needed to improve these outcomes. Ponatinib is a multi-tyrosine kinase inhibitor that targets many pathways implicated in neuroblastoma pathogenesis. We hypothesized that ponatinib would be effective against neuroblastoma in preclinical models. Methods We evaluated the effects of ponatinib on survival and migration of human neuroblastoma cells in vitro. Using orthotopic xenograft mouse models of human neuroblastoma, we analyzed tumors treated with ponatinib for growth, gross and histologic appearance, and vascularity. Results Ponatinib treatment of neuroblastoma cells resulted in decreased cell viability and migration in vitro. In mice with orthotopic xenograft neuroblastoma tumors, treatment with ponatinib resulted in decreased growth and vascularity. Conclusions Ponatinib reduces neuroblastoma cell viability in vitro and reduces tumor growth and vascularity in vivo. The antitumor effects of ponatinib suggest its potential as a novel therapeutic agent for neuroblastoma, and further preclinical testing is warranted.

Biophysical differences between chronic myelogenous leukemic quiescent and proliferating stem/progenitor cells

The treatment of chronic myeloid leukemia (CML), a clonal myeloproliferative disorder has improved recently, but most patients have not yet been cured. Some patients develop resistance to the available tyrosine kinase treatments. Persistence of residual quiescent CML stem cells (LSCs) that later resume proliferation is another common cause of recurrence or relapse of CML. Eradication of quiescent LSCs is a promising approach to prevent recurrence of CML. Here we report on new biophysical differences between quiescent and proliferating CD34+ LSCs, and speculate how this information could be of use to eradicate quiescent LSCs. Using AFM measurements on cells collected from four untreated CML patients, substantial differences are observed between quiescent and proliferating cells in the elastic modulus, pericellular brush length and its grafting density at the single cell level. The higher pericellular brush densities of quiescent LSCs are common for all samples. The significance of these observations is discussed.

[Clinical and laboratory characteristics and treatment option for Philadelphia positive acute lymphoblastic leukemia patients with ABL kinase domain mutations]

目的

探讨Ph染色体阳性急性淋巴细胞白血病(Ph⁺ ALL)ABL激酶区突变患者的临床、分子遗传学特征和生存情况，分析异基因造血干细胞移植(allo-HSCT)联合酪氨酸激酶抑制剂(TKI)在突变患者中的应用价值。

方法

回顾性分析2010年2月至2014年8月检出ABL激酶区突变Ph⁺ ALL患者初诊阶段的临床、分子遗传学特征及突变分布、预后，并比较allo-HSCT联合不同类型TKI的疗效。

结果

88例Ph⁺ ALL患者于维持治疗阶段行ABL激酶区突变监测，42例患者检出突变，中位突变时间为8个月。突变组患者中位发病年龄为40岁，较非突变组(32.5岁)大(P=0.023)；染色体复杂核型发生率高于非突变组(P=0.043)，其中以累及7号、5号染色体以及＋Ph更常见。42例突变患者共检出18个突变位点、21种突变类型，T315I突变比例最高，其余依次为E255K/V、Y253H/F、E459K。突变患者诱导治疗完全缓解率与非突变组相比差异无统计学意义，但主要分子生物学反应率显著低于非突变组(P=0.015)。突变患者2年及5年总体生存(OS)率分别为45.4%、35.0%，明显低于非突变组患者(67.8%、63.3%)(P=0.047)。存在T315I、E255K/V突变的患者中位OS时间分别为19和10个月，较其他类型突变者短(P=0.024)。42例突变患者中14例行allo-HSCT并于移植前即检出突变，其中位OS时间为29个月，长于非移植(巩固化疗联合TKI治疗)患者的17个月(P=0.034)。移植患者中14例突变检出时更换使用尼洛替尼或达沙替尼治疗，但中位OS时间与未更换者差异无统计学意义(P=0.862)。

结论

ABL激酶区突变与初诊发病年龄较高以及高基因组不稳定性紧密相关。突变类型呈现多样性和复杂性，其中以T315I和E255K/V突变更常见，且较其他类型突变者预后更差。allo-HSCT能够改善突变患者预后，但复发耐药阶段更换使用二代TKI不能明显改善突变患者生存。

Drugging the unfolded protein response in acute leukemias

The unfolded protein response (UPR), an endoplasmic reticulum (ER) stress-induced signaling cascade, is mediated by three major stress sensors IRE-1α, PERK, and ATF6α. Studies described the UPR as a critical network in selection, adaptation, and survival of cancer cells. While previous reviews focused mainly on solid cancer cells, in this review, we summarize the recent findings focusing on acute leukemias. We take into account the impact of the underlying genetic alterations of acute leukemia cells, the leukemia stem cell pool, and provide an outline on the current genetic, clinical, and therapeutic findings. Furthermore, we shed light on the important oncogene-specific regulation of individual UPR signaling branches and the therapeutic relevance of this information to answer the question if the UPR could be an attractive novel target in acute leukemias.

Bosutinib for the Treatment of Philadelphia Chromosome-Positive Leukemias

Introduction

Bosutinib is a dual ABL1 and SRC third generation tyrosine kinase inhibitor (TKI) indicated for the treatment of patients with chronic myelogenous leukemia (CML) resistant to or intolerant of other BCR-ABL1 inhibitors. Bosutinib is active against leukemia cells expressing imatinib-resistant BCR-ABL1 mutations. Mechanistically, this agent may also be beneficial for Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) because in preclinical animal models, SRC accelerates ALL disease development.

Areas Covered

Here we review the current scientific and medical literature on the role of bosutinib for the treatment of CML. We address the unique therapeutic advantages of this agent, specifically its ability to inhibit mutant BCR-ABL1 kinases conferring resistance to other TKIs and its unique safety profile consisting of mainly manageable self-limited diarrhea, not cardiovascular, side effects. Long-term toxicities reported with dasatinib, nilotinib and ponatinib have not been described with bosutinib. Lastly, we present preclinical data demonstrating that bosutinib inhibits a broader range of tyrosine kinases than any other TKI, including those implicated in acute leukemia.

Expert Opinion

We propose that future studies should explore the use of bosutinib in Ph+ ALL due to its multi-kinase inhibitory activity and its relatively long-term safety compared to other second and third generation TKIs.

Drug Therapy in the Progressed CML Patient with multi-TKI Failure

The aim of this paper is to outline pharmacotherapy of the 'third-line management of CML' (progressive disease course after sequential TKI drugs). Current management of CML with multi-TKI failure is reviewed. TKI (bosutinib, ponatinib, dasatinib, nilotinib) and non-TKI (omacetaxine mepussecinate, IFN or PEG-IFN) drugs are available. The literature search was made in PubMed with particular focus on the clinical trials, recommendations, guidelines and expert opinions, as well as international recommendations. Progressing CML disease with multi-TKI failure should be treated with alloSCT based on the availability of the donor and EBMT transplant risk scores. The TKI and non-TKI drugs shall be used to get best promising (hematological, cytogenetic, molecular) response. During the CP-CML phase of multi-TKI failure, 2nd generation TKIs (nilotinib or dasatinib) should be tried if not previously utilized. Bosutinib and ponatinib (3rd-generation TKIs) should be administered in double- or triple-TKI (imatinib and nilotinib and dasatinib) resistant patients. The presence of T315I mutation at any phase requires ponatinib or omacetaxine mepussecinate therapy before allografting. During the AP/BC-CML phase of multi-TKI failure, the most powerful TKI available (ponatinib or dasatinib if not previously used) together with chemotherapy should be given before alloSCT. Monitoring of CML disease and drug off-target risks (particularly vascular thrombotic events) are vital.

How we will treat chronic myeloid leukemia in 2016

Imatinib will become generic in 2016; assuming that its price will decrease precipitously, we expect that the economic forces will change our current practice habits. We reviewed the literature on the current recommendations to treat chronic myeloid leukemia and highlight how we plan to deal with these changes. Specifically, we propose to better characterize patients according to prognostic scores, to allow more attention to those at high risk for disease progression, e.g., 3-month guidelines and BCR/ABL1 message half-time, emphasize compliance by using contemporary technologies, and increase the importance of early monitoring. We hope that our message will open communication between providers, insurance companies and healthcare authorities to offer the best care for our patients.