Managing chronic myeloid leukemia patients intolerant to tyrosine kinase inhibitor therapy

Repurposing approved drugs for cancer therapy

BACKGROUND

Many drugs approved for other indications can control the growth of tumor cells and limit adverse events (AE).

DATA SOURCES

Literature searches with keywords 'repurposing and cancer' books, websites: https://clinicaltrials.gov/, for drug structures: https://pubchem.ncbi.nlm.nih.gov/.

AREAS OF AGREEMENT

Introducing approved drugs, such as those developed to treat diabetes (Metformin) or inflammation (Thalidomide), identified to have cytostatic activity, can enhance chemotherapy or even replace more cytotoxic drugs. Also, anti-inflammatory compounds, cytokines and inhibitors of proteolysis can be used to control the side effects of chemo- and immuno-therapies or as second-line treatments for tumors resistant to kinase inhibitors (KI). Drugs specifically developed for cancer therapy, such as interferons (IFN), the tyrosine KI abivertinib TKI (tyrosine kinase inhibitor) and interleukin-6 (IL-6) receptor inhibitors, may help control symptoms of Covid-19.

AREAS OF CONTROVERSY

Better knowledge of mechanisms of drug activities is essential for repurposing. Chemotherapies induce ER stress and enhance mutation rates and chromosome alterations, leading to resistance that cannot always be related to mutations in the target gene. Metformin, thalidomide and cytokines (IFN, tumor necrosis factor (TNF), interleukin-2 (IL-2) and others) have pleiomorphic activities, some of which can enhance tumorigenesis. The small and fragile patient pools available for clinical trials can cloud the data on the usefulness of cotreatments.

GROWING POINTS

Better understanding of drug metabolism and mechanisms should aid in repurposing drugs for primary, adjuvant and adjunct treatments.

AREAS TIMELY FOR DEVELOPING RESEARCH

Optimizing drug combinations, reducing cytotoxicity of chemotherapeutics and controlling associated inflammation.

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

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

Assessment of azithromycin as an anticancer agent for treatment of imatinib sensitive and resistant CML cells

INTRODUCTION

Chronic Myeloid Leukemia (CML) is a hematological disease which is characterized by the presence of BCR-ABL fusion protein. Imatinib (IMA), a tyrosine kinase inhibitor of BCR-ABL, is used as a frontline treatment.Although IMA aids in killing a majority of leukemia cells, it may not kill CML stem cells which are the primary roots of disease and therapy resistance. Recently, antimicrobial drugs have been gaining attention because of their selective targeting of cancer cells. Therefore, we now ask if combinational therapy of IMA with a targeted antimicrobial drug Azithromycin (AZT) can enhance the treatment efficiency in IMA resistant CML.

METHODS

K562S (IMA sensitive) and K562R (IMA resistant) cells were treated with increasing concentrations of AZT to determine its effects on cell proliferation and apoptosis. Cell viability, apoptosis, caspase3/7 activity and P-glycoprotein (Pgp) function were investigated with spectrophotometric MTT assay and flow cytometric Annexin V staining, caspase 3/7 activity, and Rhodamine123 staining assays respectively. The expression levels of pro-apoptotic (BAX, BAD and BIM), anti- apoptotic (BCL-XL and BCL-2) and drug transporter (MDR-1 and MRP-1) genes were assessed with qRT-PCR.

RESULTS

AZT treatment alone inhibited cell viability, induced apoptosis and enhanced caspase 3/7 activity in both K562S and high MDR-1 (Pgp) expressing K562R cells. Moreover, combination of AZT/IMA suppressed cell viability, induced apoptosis and caspase3/7 activity more effectively and significantly compared to K562R cells treated with only IMA or AZT. Furthermore, AZT and AZT/IMA combination decreased Pgp function in K562R cells in comparison with their controls. Based on qRT-PCR data, single AZT and combined AZT/IMA treatment also induced BAX/BCL-2 ratio significantly in both K562S and K562R cells.

CONCLUSION

Single AZT and AZT/IMA combinational treatment can be proposed as a promising and effective treatment strategy for CML. One of the mechanisms underlying the potent anticancer effect of combined AZT/IMA could be its ability to inhibit Pgp function and increase intracellular accumulation of IMA which leads to the induction of apoptosis in K562R cells.

Treatment patterns and clinical outcomes of tyrosine kinase inhibitors in chronic-phase CML in clinical practice: 3-year European SIMPLICITY data

Objectives

SIMPLICITY (NCT01244750) is an observational study of patients with chronic‐phase chronic myeloid leukemia (CP‐CML) in routine clinical practice receiving first‐line tyrosine kinase inhibitors (TKIs). We evaluated TKI treatment changes and how switching affects clinical response in patients recruited in Europe with ≥3 years of follow‐up.

Methods

The SIMPLICITY European cohort (France, Germany, Italy, the Netherlands, Russia, and Spain) included 431 patients. 370 (86%) were followed for ≥3 years.

Results

Proportions of patients experiencing treatment interruptions, TKI switching, and discontinuations decreased over 3 years’ follow‐up. Intolerance was a key driver for treatment changes. Complete cytogenetic response (CCyR) was achieved in 87.5% of patients switching TKI within 3 years of initiation vs 91.7% of non‐switchers. Major molecular response (MMR) was achieved in 82.4% of switchers vs 92.9% of non‐switchers. Over 3 years, not switching TKI was a strong predictor for achieving CCyR or MMR (both P < .05). Three‐year survival remained high, irrespective of treatment changes (95.3% switchers, 96.4% non‐switchers).

Conclusions

European patients with CP‐CML who do not switch TKI are more likely to achieve clinical response, while intolerance is a key driver for switching. Successful CML management may require careful selection of initial TKI, with early monitoring of response and intolerance.

Management of metabolic adverse events of targeted therapies and immune checkpoint inhibitors in cancer patients: an Associazione Italiana Oncologia Medica (AIOM)/Associazione Medici Diabetologi (AMD)/Società Italiana Farmacologia (SIF) multidisciplinary consensus position paper

The growing insights in the next-generation immunotherapy and the state-of-the-art advancement in targeted-agents significantly improved clinical outcome of cancer patients by pointing towards a unexplored Achilles' heel. Novel toxicity profiles have been uncovered, representing unmet medical needs. Thus, a panel of expert provide comprehensive pharmacological and clinical evidence, to provide a patient-tailored approach to metabolic adverse events associated with novel anti-cancer treatments. Prompted by the need of a multidisciplinary cooperation, a working group of Associazione Italiana Oncologia Medica (AIOM), Associazione Medici Diabetologi (AMD) and Società Italiana Farmacologia (SIF) examined the available literature data. The identification of patient risk profile and the characterization of metabolic effects of novel anti-tumour drugs is clearly a clinical challenge that can be addressed by a multidisciplinary clinical approach. Therefore, this review pinpoints the relevance of the challenging profiling of the patient suffering from dysmetabolic conditions induced by the novel therapeutics in medical oncology.

The multi-tyrosine kinase inhibitor ponatinib for chronic myeloid leukemia: Real-world data

Development of the highly selective targeted tyrosine kinase inhibitors (TKIs) has expanded the therapeutic options for chronic myeloid leukemia (CML). Patients undergoing TKI therapy should be closely monitored to ensure that the best therapeutic response and quality of life are achieved, and to control suboptimal responses and adverse events. Despite the high rate of response using current first-line TKIs, treatment failure may still occur, and resistance is considered a challenge in the treatment of patients with CML. The third-generation TKI, ponatinib, is a potent orally bioavailable pan BCR-ABL inhibitor that inhibits both wild-type and mutant BCR-ABL1 kinase, including the "gatekeeper" T315I mutation, which is resistant to all other currently available TKIs. This paper reviews the effectiveness, feasibility, and safety of ponatinib in the real-life clinical management of CML. Potential prognostic factors in identifying patients most likely to benefit from ponatinib treatment will be discussed, and case presentations illustrating situations encountered in real-life clinical practice are described. Ponatinib is effective in patients who have received prior TKIs in clinical studies as well as under real-life conditions. Nevertheless, the risk/benefit balance must be evaluated for each patient, particularly considering disease state, mutational status, treatment line, intolerance/resistance to prior TKIs, age, frailty, and specific comorbidities.

Response to Therapy, Treatment Intolerance and Tyrosine Kinase Inhibitor Cessation Eligibility in a Real-World Cohort of Chronic Myeloid Leukaemia Patients

Tyrosine kinase inhibitor (TKI) therapy has revolutionised chronic myeloid leukaemia (CML) management, it is however associated with significant side effects and economic burden. Recent studies have demonstrated that treatment free remission is possible in certain patients. The aim of this study was to characterise a real-world population in terms of response to therapy, treatment intolerance and potential eligibility for stopping treatment. Included were 105 CML patients diagnosed in Northern Ireland from March 2009-February 2018. Response to treatment was defined as per the 2009 and 2013 European Leukaemia Net guidelines. Potential for treatment cessation was assessed as per the 2017 UK Interim Expert Opinion on Discontinuing Tyrosine Kinase Inhibitor Treatment in Clinical Practice for Treatment-Free Remission in Chronic Myeloid Leukaemia. Our cytogenetic data cohort had a 12-month complete cytogenetic response rate of 66% and the molecular data cohort had a 12-month major molecular response rate of 38%. Of those commenced on 2^nd line TKI therapy 81% achieved an optimal response at 12 months. Twenty-two patients developed intolerance and required a change in TKI therapy. The commonest side effects were gastro-intestinal upset (18%), transaminitis (16%) and fluid retention (16%). In our cohort, 20% were considered eligible to stop TKI therapy. The commonest reason for ineligibility was insufficient duration of therapy (25%). We observed that 1^st and 2^nd line TKI therapy are effective but problems with failure and intolerance persist. Additionally, this study identifies a cohort of patients who may attempt TKI cessation using the UK Interim Expert Opinion report on TKI therapy discontinuation.

Efficacy and safety of nilotinib 300 mg twice daily in patients with chronic myeloid leukemia in chronic phase who are intolerant to prior tyrosine kinase inhibitors: Results from the Phase IIIb ENESTswift study

BACKGROUND

Some patients receiving a tyrosine kinase inhibitor (TKI) for the first-line treatment of chronic phase chronic myeloid leukemia (CML-CP) experience intolerable adverse events. Management strategies include dose adjustments, interrupting or discontinuing therapy, or switching to an alternative TKI.

METHODS

This multicenter, single-arm, Phase IIIb study included CML-CP patients intolerant of, but responsive to, first-line treatment with imatinib or dasatinib. All patients were switched to nilotinib 300 mg bid for up to 24 months. The primary endpoint was achievement of MR4.5 (BCR-ABL transcript level of ≤0.0032% on the International Scale) by 24 months.

RESULTS

Twenty patients were enrolled in the study (16 imatinib-intolerant, 4 dasatinib-intolerant); which was halted early because of low recruitment. After the switch to nilotinib 300 mg bid, MR4.5 at any time point up to month 24 was achieved in 10 of 20 patients (50%) in the full analysis set. Of the non-hematological adverse events associated with intolerance to prior imatinib or dasatinib, 74% resolved within 12 weeks of switching to nilotinib 300 mg bid.

CONCLUSION

Nilotinib 300 mg bid shows minimal cross intolerance in patients with CML-CP who have prior toxicities to other TKIs and can lead to deep molecular responses.

Understanding and Challenges in Taking Tyrosine Kinase Inhibitors among Malaysian Chronic Myeloid Leukemia Patients: A Qualitative Study

Background:

In Malaysia, the treatment for chronic myeloid leukemia (CML) has long been delivered under the Malaysian Patient Assistance Program (MYPAP), but research on identifying factors contributing to non-adherence to tyrosine kinase inhibitors (TKIs) is still limited. The current study explored understanding and challenges of Malaysian CML patients in taking imatinib and nilotinib.

Methods:

Semi-structured, face-to-face interviews were conducted with 13 CML patients receiving treatment at a public tertiary care center, and were analyzed using the content analysis approach.

Results:

The patients generally demonstrated inadequate knowledge, particularly of the natural history and staging of CML, the function of TKIs, and the methods used for monitoring the effectiveness of treatment. A number of them also had experiences of withholding, skipping or altering the treatment, mainly due to the life-disturbing adverse drug effects (ADRs), forgetfulness, and religious and social issues. Besides, most of them were found having limited skills in managing the ADRs, and not using prompts as reminders to take the medications. Furthermore, even though nilotinib was generally perceived as better tolerated as compared with imatinib, the inconvenience caused by the need to take it twice daily and on an empty stomach was constantly highlighted by the patients.

Conclusion:

While TKIs are widely used for CML treatment in Malaysia, the findings have revealed a lack of patient education and awareness, which warrants an integrated plan to reinforce medication adherence.

Identification of natural inhibitors of Bcr-Abl for the treatment of chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder of the hematopoietic stem cells, characterized at the molecular level by the bcr/abl gene rearrangement. Even though targeting the fusion gene product Bcr-Abl protein is a successful strategy, development of drug resistance and that of drug intolerance are currently the limitations for Bcr-Abl-targeted CML therapy. With an aim to develop natural Bcr-Abl inhibitors, we performed virtual screening (VS) of ZINC natural compound database by docking with Abl kinase using Glide software. Two natural inhibitors ZINC08764498 (hit1) and ZINC12891610 (hit2) were selected by considering their high Glide docking score and critical interaction with the hinge region residue Met-318 of Abl kinase. The reactivity of the two molecules was assessed computationally by density functional theory calculations. Further, the conformational transition, hydrogen bond interactions, and the binding energies were investigated during 10-ns molecular dynamics simulation of the Abl-hit complex. When tested in vitro, hit1 compared to hit2 showed selective inhibition of cell proliferation and induction of apoptosis in Bcr-Abl-positive K-562 leukemia cells. In summary, our results demonstrate that ZINC08764498, a coumarin derivative identified through VS, is a potential natural inhibitor for the treatment of CML.

Analysis of adverse events associated with dasatinib and nilotinib treatments in chronic-phase chronic myeloid leukemia patients outside clinical trials

We analyzed adverse events (AEs) in 201 chronic phase CML patients treated with nilotinib (n = 120) or dasatinib (n = 81) as first- or second-line therapy. The dasatinib group had significantly higher grade 3-4 AEs compared to the nilotinib group (22 vs. 54%, p < 0.001), and had more frequent dose reduction, interruption, and discontinuation (p < 0.001, p = 0.004, and p = 0.006, respectively). Of 59 patients who discontinued treatment, 47 (80%) discontinued treatment due to AEs; 50% of the AEs causing drug discontinuation were of grade 2 severity. Compared to the second-line setting, discontinuation occurred more rapidly in the first-line setting (2.9 vs. 15.6 months, p = 0.015). Pleural effusion occurred in 35% (28/81) of the patients with dasatinib and led to dasatinib discontinuation in 14 patients (grade 2 of 79%). Pulmonary artery hypertension occurred in one patient with dasatinib. Stroke, acute coronary syndrome, and peripheral artery occlusive disease occurred in 5% (6/120) of the patients treated with nilotinib. The dasatinib group had shorter event-free survival than nilotinib group (first-line, p = 0.051; second-line, p = 0.025). In the clinical practice setting, nilotinib or dasatinib use was more frequently interrupted than recommended by guidelines in association with less severe AEs. We believe this phenomenon is attributable to the availability of other TKIs.

Bridging academic science and clinical research in the search for novel targeted anti-cancer agents

This review starts with a brief history of drug discovery & development, and the place of Asia in this worldwide effort discussed. The conditions and constraints of a successful translational R&D involving academic basic research and clinical research are discussed and the Singapore model for pursuit of open R&D described. The importance of well-characterized, validated drug targets for the search for novel targeted anti-cancer agents is emphasized, as well as a structured, high quality translational R&D. Furthermore, the characteristics of an attractive preclinical development drug candidate are discussed laying the foundation of a successful preclinical development. The most frequent sources of failures are described and risk management at every stage is highly recommended. Organizational factors are also considered to play an important role. The factors to consider before starting a new drug discovery & development project are described, and an example is given of a successful clinical project that has had its roots in local universities and was carried through preclinical development into phase I clinical trials.

Management of hyperglycemia from epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) targeting T790M-mediated resistance

Epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) patients are associated with sensitivity to small molecule tyrosine kinase inhibitors (TKIs) such as erlotinib, gefitinib, and afatinib. Although studies show an increased progression free survival (PFS) with use of EGFR TKIs in the first-line setting, most patients will develop resistance to therapy after the first 8-16 months. T790M is an acquired resistance mutation reported in 60-70% of patients who initially responded to a prior EGFR TKI. Recently, EGFR TKIs targeting T790M have been developed to overcome resistance with positive results in PFS and objective response rate in patients who have had disease progression on at least one TKI. Two EGFR TKIs targeting T790M, AZD9291 and rociletinib, are new active treatment options for NSCLC but differ in adverse effect profiles. Dose-limiting hyperglycemia has been reported with rociletinib and has required dose reduction, an oral antihyperglycemic, or both, without discontinuation of therapy. This suggests that patients may be effectively treated chronically for hyperglycemia associated with EGFR TKIs targeting T790M, however, guidelines for treatment of hyperglycemia in this setting have not been published. We discuss mechanisms of hyperglycemia associated with TKIs and initial management of hyperglycemia, including benefits and limitations of oral antihyperglycemic options, adjustment of therapy based on grade of hyperglycemia, and recommendations for follow-up glucose monitoring.

Variability in bioavailability of small molecular tyrosine kinase inhibitors

Small molecular tyrosine kinase inhibitors (smTKIs) are in the centre of the very quickly expanding area of personalized chemotherapy and oral applicability thereof. The number of drugs in this class is rapidly growing, with twenty current approvals by both the European Medicines Agency (EMA) and the Food and Drug Administration (FDA). The drugs are, however, generally characterized by a poor oral, and thus variable, bioavailability. This results in significant variation in plasma levels and exposure. The cause is a complex interplay of factors, including poor aqueous solubility, issued permeability, membrane transport and enzymatic metabolism. Additionally, food and drug-drug interactions can play a significant role. The issues related with an impaired bioavailability generally receive little attention. To the best of our knowledge, this article is the first to provide an overview of the factors that determine the bioavailability of the smTKIs.