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

Targeting the RET tyrosine kinase in neuroblastoma: A review and application of a novel selective drug design strategy

The RET (REarranged during Transfection) gene, which encodes for a transmembrane receptor tyrosine kinase, is an established oncogene associated with the etiology and progression of multiple types of cancer. Oncogenic RET mutations and rearrangements resulting in gene fusions have been identified in many adult cancers, including medullary and papillary thyroid cancers, lung adenocarcinomas, colon and breast cancers, and many others. While genetic RET aberrations are much less common in pediatric solid tumors, increased RET expression has been shown to be associated with poor prognosis in children with solid tumors such as neuroblastoma, prompting an interest in RET inhibition as a form of therapy for these children. A number of kinase inhibitors currently in use for patients with cancer have RET inhibitory activity, but these inhibitors also display activity against other kinases, resulting in unwanted side effects and limiting their safety and efficacy. Recent efforts have been focused on developing more specific RET inhibitors, but due to high levels of conservation between kinase binding pockets, specificity remains a drug design challenge. Here, we review the background of RET as a potential therapeutic target in neuroblastoma tumors and the results of recent preclinical studies and clinical trials evaluating the safety and efficacy of RET inhibition in adults and children. We also present a novel approach to drug discovery leveraging the chemical phenomenon of atropisomerism to develop specific RET inhibitors and present preliminary data demonstrating the efficacy of a novel RET inhibitor against neuroblastoma tumor cells.

Ponatinib: An update on its drug targets, therapeutic potential and safety

Leukemia is a malignancy of the hematopoietic system, and as its pathogenesis has become better understood, three generations of tyrosine kinase inhibitors (TKIs) have been developed. Ponatinib is the third-generation breakpoint cluster region (BCR) and Abelson (ABL) TKI, which has been influential in the leukemia therapy for a decade. Moreover, ponatinib is a potent multi-target kinase inhibitor that acts on various kinases, such as KIT, RET, and Src, making it a promising treatment option for triple-negative breast cancer (TNBC), lung cancer, myeloproliferative syndrome, and other diseases. The drug's significant cardiovascular toxicity poses a significant challenge to its clinical use, requiring the development of strategies to minimize its toxicity and side effects. In this article, the pharmacokinetics, targets, therapeutic potential, toxicity and production mechanism of ponatinib will be reviewed. Furthermore, we will discuss methods to reduce the drug's toxicity, providing new avenues for research to improve its safety in clinical use.

FYN: emerging biological roles and potential therapeutic targets in cancer

Src family protein kinases (SFKs) play a key role in cell adhesion, invasion, proliferation, survival, apoptosis, and angiogenesis during tumor development. In humans, SFKs consists of eight family members with similar structure and function. There is a high level of overexpression or hyperactivity of SFKs in tumor, and they play an important role in multiple signaling pathways involved in tumorigenesis. FYN is a member of the SFKs that regulate normal cellular processes. Additionally, FYN is highly expressed in many cancers and promotes cancer growth and metastasis through diverse biological functions such as cell growth, apoptosis, and motility migration, as well as the development of drug resistance in many tumors. Moreover, FYN is involved in the regulation of multiple cancer-related signaling pathways, including interactions with ERK, COX-2, STAT5, MET and AKT. FYN is therefore an attractive therapeutic target for various tumor types, and suppressing FYN can improve the prognosis and prolong the life of patients. The purpose of this review is to provide an overview of FYN's structure, expression, upstream regulators, downstream substrate molecules, and biological functions in tumors.

Targeting Oncogenic Transcriptional Networks in Neuroblastoma: From N-Myc to Epigenetic Drugs

Neuroblastoma (NB) is one of the most frequently occurring neurogenic extracranial solid cancers in childhood and infancy. Over the years, many pieces of evidence suggested that NB development is controlled by gene expression dysregulation. These unleashed programs that outline NB cancer cells make them highly dependent on specific tuning of gene expression, which can act co-operatively to define the differentiation state, cell identity, and specialized functions. The peculiar regulation is mainly caused by genetic and epigenetic alterations, resulting in the dependency on a small set of key master transcriptional regulators as the convergence point of multiple signalling pathways. In this review, we provide a comprehensive blueprint of transcriptional regulation bearing NB initiation and progression, unveiling the complexity of novel oncogenic and tumour suppressive regulatory networks of this pathology. Furthermore, we underline the significance of multi-target therapies against these hallmarks, showing how novel approaches, together with chemotherapy, surgery, or radiotherapy, can have substantial antineoplastic effects, disrupting a wide variety of tumorigenic pathways through combinations of different treatments.

Receptor-Tyrosine Kinase Inhibitor Ponatinib Inhibits Meningioma Growth In Vitro and In Vivo

To date, there is no standard-of-care systemic therapy for the treatment of aggressive meningiomas. Receptor tyrosine kinases (RTK) are frequently expressed in aggressive meningiomas and are associated with poor survival. Ponatinib is a FDA- and EMA-approved RTK inhibitor and its efficacy in meningioma has not been studied so far. Therefore, we investigated ponatinib as a potential drug candidate against meningioma. Cell viability and cell proliferation of ponatinib-treated meningioma cells were assessed using crystal violet assay, manual counting and BrdU assay. Treated meningioma cell lines were subjected to flow cytometry to evaluate the effects on cell cycle and apoptosis. Meningioma-bearing mice were treated with ponatinib to examine antitumor effects in vivo. qPCR was performed to assess the mRNA levels of tyrosine kinase receptors after ponatinib treatment. Full-length cDNA sequencing was carried out to assess differential gene expression. IC50 values of ponatinib were between 171.2 and 341.9 nM in three meningioma cell lines. Ponatinib induced G0/G1 cell cycle arrest and subsequently led to an accumulation of cells in the subG1-phase. A significant induction of apoptosis was observed in vitro. In vivo, ponatinib inhibited meningioma growth by 72.6%. Mechanistically, this was associated with downregulation of PDGFRA/B and FLT3 mRNA levels, and mitochondrial dysfunction. Taken together, ponatinib is a promising candidate for targeted therapy in the treatment of aggressive meningioma.

Synthetic Heterocyclic Derivatives as Kinase Inhibitors Tested for the Treatment of Neuroblastoma

In the last few years, small molecules endowed with different heterocyclic scaffolds have been developed as kinase inhibitors. Some of them are being tested at preclinical or clinical levels for the potential treatment of neuroblastoma (NB). This disease is the most common extracranial solid tumor in childhood and is responsible for 10% to 15% of pediatric cancer deaths. Despite the availability of some treatments, including the use of very toxic cytotoxic chemotherapeutic agents, high-risk (HR)-NB patients still have a poor prognosis and a survival rate below 50%. For these reasons, new pharmacological options are urgently needed. This review focuses on synthetic heterocyclic compounds published in the last five years, which showed at least some activity on this severe disease and act as kinase inhibitors. The specific mechanism of action, selectivity, and biological activity of these drug candidates are described, when established. Moreover, the most remarkable clinical trials are reported. Importantly, kinase inhibitors approved for other diseases have shown to be active and endowed with lower toxicity compared to conventional cytotoxic agents. The data collected in this article can be particularly useful for the researchers working in this area.

Novel Treatments and Technologies Applied to the Cure of Neuroblastoma

Neuroblastoma (NB) is the most common extracranial solid tumour in childhood, accounting for approximately 15% of all cancer-related deaths in the paediatric population1. It is characterised by heterogeneous clinical behaviour in neonates and often adverse outcomes in toddlers. The overall survival of children with high-risk disease is around 40-50% despite the aggressive treatment protocols consisting of intensive chemotherapy, surgery, radiation therapy and hematopoietic stem cell transplantation2,3. There is an ongoing research effort to increase NB's cellular and molecular biology knowledge to translate essential findings into novel treatment strategies. This review aims to address new therapeutic modalities emerging from preclinical studies offering a unique translational opportunity for NB treatment.

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.

Regorafenib is effective against neuroblastoma in vitro and in vivo and inhibits the RAS/MAPK, PI3K/Akt/mTOR and Fos/Jun pathways

BACKGROUND

Regorafenib is an inhibitor of multiple kinases with aberrant expression and activity in neuroblastoma tumours that have potential roles in neuroblastoma pathogenesis.

METHODS

We evaluated neuroblastoma cells treated with regorafenib for cell viability and confluence, and analysed treated cells for apoptosis and cell cycle progression. We evaluated the efficacy of regorafenib in vivo using an orthotopic xenograft model. We evaluated regorafenib-mediated inhibition of kinase targets and performed reverse-phase protein array (RPPA) analysis of neuroblastoma cells treated with regorafenib. Lastly, we evaluated the efficacy and effects of the combination of regorafenib and 13-cis-retinoic acid on intracellular signalling.

RESULTS

Regorafenib treatment resulted in reduced neuroblastoma cell viability and confluence, with both induction of apoptosis and of cell cycle arrest. Regorafenib treatment inhibits known receptor tyrosine kinase targets RET and PDGFRβ and intracellular signalling through the RAS/MAPK, PI3K/Akt/mTOR and Fos/Jun pathways. Regorafenib is effective against neuroblastoma tumours in vivo, and the combination of regorafenib and 13-cis-retinoic acid demonstrates enhanced efficacy compared with regorafenib alone.

CONCLUSIONS

The effects of regorafenib on multiple intracellular signalling pathways and the potential additional efficacy when combined with 13-cis-retinoic acid represent opportunities to develop treatment regimens incorporating regorafenib for children with neuroblastoma.

Targeting the Extra-Cellular Matrix-Tumor Cell Crosstalk for Anti-Cancer Therapy: Emerging Alternatives to Integrin Inhibitors

The extracellular matrix (ECM) is a complex network composed of a multitude of different macromolecules. ECM components typically provide a supportive structure to the tissue and engender positional information and crosstalk with neighboring cells in a dynamic reciprocal manner, thereby regulating tissue development and homeostasis. During tumor progression, tumor cells commonly modify and hijack the surrounding ECM to sustain anchorage-dependent growth and survival, guide migration, store pro-tumorigenic cell-derived molecules and present them to enhance receptor activation. Thereby, ECM potentially supports tumor progression at various steps from initiation, to local growth, invasion, and systemic dissemination and ECM-tumor cells interactions have long been considered promising targets for cancer therapy. Integrins represent key surface receptors for the tumor cell to sense and interact with the ECM. Yet, attempts to therapeutically impinge on these interactions using integrin inhibitors have failed to deliver anticipated results, and integrin inhibitors are still missing in the emerging arsenal of drugs for targeted therapies. This paradox situation should urge the field to reconsider the role of integrins in cancer and their targeting, but also to envisage alternative strategies. Here, we review the therapeutic targets implicated in tumor cell adhesion to the ECM, whose inhibitors are currently in clinical trials and may offer alternatives to integrin inhibition.

Applications and prospects of targeted therapy for neuroblastoma

Background

Neuroblastoma is an extremely malignant tumor in children. For advanced or recurrent cases, existing treatment modalities are limited and efficacy remains disappointing. With the improvement in understanding of molecular biology of neuroblastoma and the development of clinical trials of targeted drug therapy, a variety of targeted therapies for neuroblastoma have appeared.

Data sources

All the recent literatures on targeted therapies of neuroblastoma on PubMed were searched and reviewed.

Results

This article reviewed targeted therapies of neuroblastoma going through clinical trials and obtained preliminary results. The features, advantages and disadvantages of targeted radiation therapy,

immunotherapy, gene and pathway molecular inhibitor and angiogenesis inhibitor were discussed.

Conclusion

This study provides references for better understanding the current progress of targeted therapies for neuroblastoma.

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

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

Ponatinib: a novel multi-tyrosine kinase inhibitor against human malignancies

Human malignancies are often the result of overexpressed and constitutively active receptor and non-receptor tyrosine kinases, which ultimately lead to the mediation of key tumor-driven pathways. Several tyrosine kinases (ie, EGFR, FGFR, PDGFR, VEGFR), are aberrantly activated in most common tumors, including leukemia, glioblastoma, gastrointestinal stromal tumors, non-small-cell lung cancer, and head and neck cancers. Iclusig™ (ponatinib, previously known as AP24534) is an orally active multi-tyrosine kinase inhibitor and is currently approved by the US Food and Drug Administration for patients with chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia, specifically targeting the BCR-ABL gene mutation, T315I. Due to ponatinib's unique multi-targeted characteristics, further studies have demonstrated its ability to target other important tyrosine kinases (FGFR, PDGFR, SRC, RET, KIT, and FLT1) in other human malignancies. This review focuses on the available data of ponatinib and its molecular targets for treatment in various cancers, with a discussion on the broader potential of this agent in other cancer indications.

Recent Studies on Ponatinib in Cancers Other Than Chronic Myeloid Leukemia

Ponatinib is a third line drug for the treatment of chronic myeloid leukemia patients, especially those that develop the gatekeeper mutation T315I, which is resistant to the first and the second line drugs imatinib, nilotinib, dasatinib and bosutinib. The compound was first identified as a pan Bcr-Abl and Src kinase inhibitor. Further studies have indicated that it is a multitargeted inhibitor that is active on FGFRs, RET, AKT, ERK1/2, KIT, MEKK2 and other kinases. For this reason, the compound has been evaluated on several cancers in which these kinases play important roles, including thyroid, breast, ovary and lung cancer, neuroblastoma, rhabdoid tumours and in myeloproliferative disorders. Ponatinib is also being tested in clinical trials to evaluate its activity in FLT3-ITD acute myelogenous leukemia, head and neck cancers, certain type of lung cancer, gastrointestinal stromal tumours and other malignancies. In this review we report the most recent preclinical and clinical studies on ponatinib in cancers other than CML, with the aim of giving a complete overview of this interesting compound.

A High-Content Screening of Anticancer Compounds Suggests the Multiple Tyrosine Kinase Inhibitor Ponatinib for Repurposing in Neuroblastoma Therapy

Novel druggable targets have been discovered in neuroblastoma (NB), paving the way for more effective treatments. However, children with high-risk NB still show high mortality rates prompting for a search of novel therapeutic options. Here, we aimed at repurposing FDA-approved drugs for NB treatment by performing a high-content screening of a 349 anticancer compounds library. In the primary screening, we employed three NB cell lines, grown as three-dimensional (3D) multicellular spheroids, which were treated with 10 μmol/L of the library compounds for 72 hours. The viability of 3D spheroids was evaluated using a high-content imaging approach, resulting in a primary hit list of 193 compounds. We selected 60 FDA-approved molecules and prioritized drugs with multi-target activity, discarding those already in use for NB treatment or enrolled in NB clinical trials. Hence, 20 drugs were further tested for their efficacy in inhibiting NB cell viability, both in two-dimensional and 3D models. Dose-response curves were then supplemented with the data on side effects, therapeutic index, and molecular targets, suggesting two multiple tyrosine kinase inhibitors, ponatinib and axitinib, as promising candidates for repositioning in NB. Indeed, both drugs showed induction of cell-cycle block and apoptosis, as well as inhibition of colony formation. However, only ponatinib consistently affected migration and inhibited invasion of NB cells. Finally, ponatinib also proved effective inhibition of tumor growth in orthotopic NB mice, providing the rationale for its repurposing in NB therapy. Mol Cancer Ther; 17(7); 1405-15. ©2018 AACR.