Nilotinib: a new tyrosine kinase inhibitor for the treatment of chronic myelogenous leukemia

Biological Significance of EphB4 Expression in Cancer

Eph receptors and their Eph receptor-interacting (ephrin) ligands comprise a vital cell communication system with several functions. In cancer cells, there was evidence of bilateral Eph receptor signaling with both tumor-suppressing and tumor-promoting actions. As a member of the Eph receptor family, EphB4 has been linked to tumor angiogenesis, growth, and metastasis, which makes it a viable and desirable target for drug development in therapeutic applications. Many investigations have been conducted over the last decade to elucidate the structure and function of EphB4 in association with its ligand ephrinB2 for its involvement in tumorigenesis. Although several EphB4-targeting drugs have been investigated, and some selective inhibitors have been evaluated in clinical trials. This article addresses the structure and function of the EphB4 receptor, analyses its possibility as an anticancer therapeutic target, and summarises knowledge of EphB4 kinase inhibitors. To summarise, EphB4 is a difficult but potential treatment option for cancers.

Development of Pigmentation-Regulating Agents by Drug Repositioning

Skin color is determined by the processes of melanin synthesis and distribution. Problems in various molecules or signaling pathways involved in melanin synthesis contribute to skin pigmentation defects. Several trials have been conducted on the production of pigmentation-regulating agents, and drug repositioning has emerged as a modern technique to identify new uses for existing drugs. Our research team has researched substances or drugs associated with pigmentation control and, as a result, nilotinib, sorafenib, and ICG-001 have been found to promote pigmentation, while 5-iodotubercidin inhibits pigmentation. Therefore, these substances or medications were suggested as potential therapeutics for pigmentation disorders by drug repositioning.

A systematic approach for stability-indicating HPLC method optimization for Nilotinib bulk through design of experiments: Application towards characterization of base degradation products by mass spectrometry

A novel and reliable stability-indicating high-performance liquid chromatography method was developed using design of experiments. Under forced degradation conditions (hydrolysis, oxidative, photolytic and thermal) Nilotinib produced five major degradation products utilizing sodium hydroxide in base hydrolysis. The degradation products were separated by Hypersil ODS column (150×4.6mm i.d., 5μ) utilizing methanol and 10mM ammonium acetate (pH 3.0, adjusted with acetic acid) as mobile phase in gradient elusion mode at a flow rate of 1.2mL/min column temperature set at 35°C and UV detection at 263nm. Tandem mass spectrometry method was used to characterize the base degradation products by accurate mass measurements. The developed method was found to be linear, accurate, precise and selective for the separation of Nilotinib from its degradation products as per the International Conference on Harmonisation guidelines. The structures of the degradation products have been elucidated, of which three degradation products were reported for the first time.

Nilotinib-induced liver injury: A case report

INTRODUCTION

Nilotinib is a selective inhibitor of the BCR-ABL tyrosine kinase receptor and is used in the management of chronic myelogenous leukemia (CML). Nilotinib therapy at high doses is associated with elevated serum bilirubin levels. If the serum bilirubin level exceeds 3 times the upper limit of normal, the recommendation is to either adjust nilotinib dosage or temporarily discontinue the treatment. However, it is unclear whether hyperbilirubinemia indicates obvious liver histology damage.

PATIENT CONCERNS

A 24-year-old man with confirmed CML was treated with nilotinib therapy and developed hyperbilirubinemia after the treatment. Although the first remission of the hyperbilirubinemia was achieved after dose adjustment, the hematological parameters deteriorated. Thus, we initiated an antineoplastic therapy (at the standard dose) until complete remission of the CML was achieved. The pathogenic mechanism of hyperbilirubinemia may be related to the inhibition of uridine diphosphate-glucuronosyltransferase (UGT1A1) activity. Liver histological analysis revealed no significant liver damage. In addition, the patient had no family history of hyperbilirubinemia and liver disease.

DIAGNOSIS

The patient was admitted to our hospital under the diagnosis of hyperbilirubinemia, and histopathology by liver biopsy showed no obvious damage. We also detected a UGT1A1 mutation [ex1 c.686C > A (p.Pro229Gln)] in the patient and his mother.

INTERVENTIONS

When the nilotinib dose was decreased to 300 mg daily, the total bilirubin (TBIL) level decreased to 30 to 50 μmol/L for 1 month. However, because the Bcr-Abl/Abl ratio did not correspond to the major molecular response (MMR; <0.1%), the nilotinib dose was readjusted to 400 mg daily. One week later, the TBIL and indirect bilirubin levels increased to 89 and 79 μmol/L, respectively. The levels of alanine transaminase and other liver functional indicators were normal.

OUTCOMES

A Naranjo Adverse Drug Reaction (ADR) Probability Scale score of 13 indicates that hyperbilirubinemia is attributed to ADR caused by nilotinib rather than by drug-induced liver injury.

CONCLUSION

Although reducing the nilotinib dose can alleviate the occurrence of hyperbilirubinemia, the effect of MMR is also reduced. Treatment of CML without dose adjustment or discontinuation of nilotinib therapy may be more advantageous.

The Perplexity of Synergistic Duality: Inter-molecular Mechanisms of Communication in BCR-ABL1

BACKGROUND

Aberrant and proliferative expression of the oncogene BCR-ABL in bone marrow cells is one of the prime causes of Chronic Myeloid Leukemia (CML). It has been established that the tyrosine kinase domain of the BCR-ABL protein is a potential therapeutic target for the treatment of CML. Although the first and second line inhibitors against the enzyme are available, recent studies have indicated that monotherapeutic resistance has become a great challenge.

OBJECTIVE

In recent studies, the dual inhibition of BCR-ABL by Nilotinib and Asciminib has been shown to overcome drug resistance. This prompted us to investigate the dynamics behind this novel drug combination.

METHODS

By the utilization of a wide range of computational tools, we defined and compared BCR-ABL's structural and dynamic characteristics when bound as a dual inhibitor system.

RESULTS

Conformational ensemble analysis presented a sustained inactive protein, as the activation loop, inclusive of the characteristic Tyr257, remained in an open position due to the unassailable binding of Asciminib at the allosteric site. Nilotinib also indicated stronger binding at the catalytic site in the presence of Asciminib, thus exposing new avenues in treating Nilotinib-resistance. This was in accordance with intermolecular hydrogen bond interactions with key binding site residues GLU399, Asn259 and Thr252.

CONCLUSION

The investigations carried out in this study gave rise to new possibilities in the treatment of resistance in CML, as well as assisting in the design of novel and selective inhibitors as dual anti-cancer drugs.

Targeting the RAS pathway in melanoma

Metastatic melanoma is a highly lethal type of skin cancer and is often refractory to all traditional chemotherapeutic agents. Key insights into the genetic makeup of melanoma tumors have led to the development of promising targeted agents. An activated RAS pathway, anchored by oncogenic BRAF, appears to be the central motor driving melanoma proliferation. Although recent clinical trials have brought enormous hope to patients with melanoma, adverse effects and novel escape mechanisms of these inhibitors have already emerged. Definition of the limits of the first successful targeted therapies will provide the basis for further advances in management of disseminated melanoma. In this review, the current state of targeted therapy for melanoma is discussed, including the potent BRAF(V600E) inhibitor vemurafenib.

Novel oral anticancer drugs: a review of adverse drug reactions, interactions and patient adherence

Each aspect of oncological care is widely affected by the spread of oral anticancer agents, which raises several questions in terms of safe medication use and patient adherence. Over the past decade targeted therapies have appeared in clinical practice and revolutionized the pharmacological treatment of malignancies. Regular patient – doctor visits and proper patient education is crucial in order to comply with the therapy previously agreed upon with the oncologist, to increase patient adherence, to detect and to treat adverse effects in early stages. Since the information on the new medicines in Hungarian language is sparse it is the intention of the authors to give an overview of the basic knowledge, patient safety issues, adverse effects and interactions. Official drug information summaries and data on pharmacokinetics, interactions and adverse effects from the literature are reviewed as the basis for this overview. Orv. Hetil., 2012, 153, 66–78.

Cell-centric view of apoptosis and apoptotic cell death-inducing antitumoral strategies

Programmed cell death and especially apoptotic cell death, occurs under physiological conditions and is also desirable under pathological circumstances. However, the more we learn about cellular signaling cascades, the less plausible it becomes to find restricted and well-limited signaling pathways. In this context, an extensive description of pathway-connections is necessary in order to point out the main regulatory molecules as well as to select the most appropriate therapeutic targets. On the other hand, irregularities in programmed cell death pathways often lead to tumor development and cancer-related mortality is projected to continue increasing despite the effort to develop more active and selective antitumoral compounds. In fact, tumor cell plasticity represents a major challenge in chemotherapy and improvement on anticancer therapies seems to rely on appropriate drug combinations. An overview of the current status regarding apoptotic pathways as well as available chemotherapeutic compounds provides a new perspective of possible future anticancer strategies.

Real-time fluorescent resonance energy transfer analysis to monitor drug resistance in chronic myelogenous leukemia

Despite the initial effectiveness of oncogene-directed cancer therapeutics, acquired drug resistance remains the ultimate "Achilles' heel" for long-term durable remission in cancer patients. Acquisition of drug resistance is not more evident elsewhere than in the use of tyrosine kinase inhibitors, imatinib and dasatinib, for patients with chronic myelogenous leukemia. Hence, even though imatinib initially produces remission in the chronic phase, ultimately these therapeutics fail via the emergence of drug resistance, in which chronic myelogenous leukemia could inevitably progress to a terminal blast phase culminating in fatal outcome. Technically, it is challenging to predict the onset of drug resistance in a small number of oncogene-transformed cells, making the decision of when and how to employ second-generation tyrosine kinase inhibitors, or employ novel compounds that would be of benefit in treating drug-resistant Bcr-Abl mutants mainly retrospective. Here, we characterize a rapid and sensitive real-time fluorescent resonance energy transfer-based assay that is able to detect the in vivo activity of Bcr-Abl and its inhibition by small molecule compounds. Due to its real-time and in vivo nature, such an approach has the potential to monitor a drug-resistant phenotype, as well as to identify pharmaceutical agents that inhibit drug-resistant Bcr-Abl oncoproteins in vivo.

The dual kinase complex FAK-Src as a promising therapeutic target in cancer

Focal adhesion kinase (FAK) and steroid receptor coactivator (Src) are intracellular (nonreceptor) tyrosine kinases that physically and functionally interact to promote a variety of cellular responses. Plenty of reports have already suggested an additional central role for this complex in cancer through its ability to promote proliferation and anoikis resistance in tumor cells. An important role for the FAK/Src complex in tumor angiogenesis has also been established. Furthermore, FAK and Src have been associated with solid tumor metastasis through their ability to promote the epithelial mesenchymal transition. In fact, a strong correlation between increased FAK/Src expression/phosphorylation and the invasive phenotype in human tumors has been found. Additionally, an association for FAK/Src with resistances to the current anticancer therapies has already been established. Currently, novel anticancer agents that target FAK or Src are under development in a broad variety of solid tumors. In this article we will review the normal cellular functions of the FAK/Src complex as an effector of integrin and/or tyrosine kinase receptor signaling. We will also collect data about their role in cancer and we will summarize the most recent data from the FAK and Src inhibitors under clinical and preclinical development. Furthermore, the association of both these proteins with chemotherapy and hormonal therapy resistances, as a rationale for new combined therapeutic approaches with these novel agents, to abrogate treatment associated resistances, will also be reviewed.

Coexisting with clonal evolution and BCR-ABL mutant in CML patients treated with second-generation tyrosine kinase inhibitors predict the discrepancy of in vitro drug sensitivity

PURPOSE

Second-generation tyrosine kinase inhibitors (second TKIs) such as nilotinib and dasatinib control the activity of most ABL kinase domain mutations observed in patients with imatinib resistance. Although in vitro data show that both agents can inhibit all mutations except T315I, some discrepancies have been observed in a small subset of mutation clones. Cytogenetic clonal evolution is the important resistance mechanism of chronic myeloid leukemia (CML). Accordingly, we observed the clinical significance of coexisting with clonal evolution and BCR-ABL mutant in CML patients treated with second TKIs.

MATERIALS AND METHODS

We monitored BCR-ABL transcript kinetics, interrelationship of clones expressing non-mutated and mutant transcripts and clonal aberrations within Philadelphia (Ph) positive and negative clones, respectively, in eight patients with CML receiving dasatinib or nilotinib for 3~41 months.

RESULTS

Clinical responses were correlated with in vitro sensitivity of the BCR-ABL mutants to the second TKIs in four patients. Four patients showed resistance to the second TKIs as compared to in vitro observations; three of them developed chromosomal abnormalities in the Ph chromosome positive or negative metaphases. Another patient lost the original mutation but acquired a more resistant new mutation and became resistant to the second TKI.

CONCLUSION

Cytogenetic clonal evolution is an independent poor prognostic factor in CML, which could explain the onset of mechanisms for second TKIs resistance to ABL kinase domain mutations. The results indicate that an additional evaluation of chromosomal abnormalities is warranted when BCR-ABL mutants are more resistant than indicated by in vitro data.