Repotrectinib (TPX-0005), effectively reduces growth of ALK driven neuroblastoma cells

Macrocycles and macrocyclization in anticancer drug discovery: Important pieces of the puzzle

Increasing disease-related proteins have been identified as novel therapeutic targets. Macrocycles are emerging as potential solutions, bridging the gap between conventional small molecules and biomacromolecules in drug discovery. Inspired by successful macrocyclic drugs of natural origins, macrocycles are attracting more attention for enhanced binding affinity and target selectivity. Due to the conformation constraint and structure preorganization, macrocycles can reach bioactive conformations more easily than parent acyclic compounds. Also, rational macrocyclization combined with sequent structural modification will help improve oral bioavailability and combat drug resistance. This review introduces various strategies to enhance membrane permeability in macrocyclization and subsequent modification, such as N-methylation, intramolecular hydrogen bonding modulation, isomerization, and reversible bicyclization. Several case studies highlight macrocyclic inhibitors targeting kinases, HDAC, and protein-protein interactions. Finally, some macrocyclic agents targeting tumor microenvironments are illustrated.

Repotrectinib: First Approval

Repotrectinib (AUGTYRO™) is a next-generation, oral, small-molecule kinase inhibitor of proto-oncogene tyrosine-protein kinase ROS1 (ROS1) and tropomyosin receptor tyrosine kinases (TRKs) TRKA, TRKB, and TRKC. It is being developed by Turning Point Therapeutics, a wholly owned subsidiary of Bristol-Myers Squibb (BMS), for the treatment of locally advanced or metastatic solid tumours, including non-small cell lung cancer (NSCLC). Repotrectinib is a next-generation tyrosine kinase inhibitor rationally designed to inhibit ROS1 and TRK fusion, including in the presence of resistance mutations such as solvent-front mutations. In November 2023, repotrectinib received its first approval in the USA for the treatment of adults with locally advanced or metastatic ROS1-positive NSCLC. Repotrectinib is under regulatory review in China and the EU for NSCLC. Clinical studies of repotrectinib are ongoing in several countries in patients with NSCLC and other solid tumours (including primary central nervous system cancer) across both adult and paediatric patient populations. In addition, preclinical investigation of repotrectinib in multiple myeloma is underway in the USA. This article summarizes the milestones in the development of repotrectinib leading to this first approval for the treatment of locally advanced or metastatic ROS1-positive NSCLC.

ALK inhibitors increase ALK expression and sensitize neuroblastoma cells to ALK.CAR-T cells

Selection of the best tumor antigen is critical for the therapeutic success of chimeric antigen receptor (CAR) T cells in hematologic malignancies and solid tumors. The anaplastic lymphoma kinase (ALK) receptor is expressed by most neuroblastomas while virtually absent in most normal tissues. ALK is an oncogenic driver in neuroblastoma and ALK inhibitors show promising clinical activity. Here, we describe the development of ALK.CAR-T cells that show potent efficacy in monotherapy against neuroblastoma with high ALK expression without toxicity. For neuroblastoma with low ALK expression, combination with ALK inhibitors specifically potentiates ALK.CAR-T cells but not GD2.CAR-T cells. Mechanistically, ALK inhibitors impair tumor growth and upregulate the expression of ALK, thereby facilitating the activity of ALK.CAR-T cells against neuroblastoma. Thus, while neither ALK inhibitors nor ALK.CAR-T cells will likely be sufficient as monotherapy in neuroblastoma with low ALK density, their combination specifically enhances therapeutic efficacy.

The promising impact of Bemcentinib and Repotrectinib on sleep impairment in Alzheimer's disease

Alzheimer's disease (AD), the most prevalent neurodegenerative disease, demands effective medication to alleviate symptoms. This study focused on sleep impairment as an overt clinical symptom and tauopathy as a prominent molecular symptom of this disease. Multiple compounds from three biomolecule libraries (719 compounds; ChemDiv:366 - ChEMBL:180 - PubChem:173) were evaluated for potential binding affinity and safety using AutoDock Vina and pkCSM, respectively, resulting in the selection of four candidate compounds (Lestaurtinib, Repotrectinib, Bemcentinib, and Zotiraciclib). Due to the similarity of Repotrectinib and Bemcentinib binding sites to ATP, 300 ns Martini 3 coarse-grained molecular dynamics (MD) was performed on these two molecules and ATP by NAMD. The stability of tau protein in the presence of drugs was assessed using a 200 ns Martini 3 MD simulation. Binding site analysis discloses Bemcentinib and Repotrectinib as two inhibitors occupying most amino acids in binding with ATP. The RMSD and RMS average correlation results revealed protein containing Bemcentinib and Repotrectinib to have a more stable state compared to ATP in the first 220 ns simulation. There was only a single detachment of Bemcentinib, while Repotrictinib detached twice at the end of the simulation. Eventually, adding Bemcentinib and Repotrectinib to the enzyme-tau complex significantly increased the number of tau detachments during the 200 ns simulation. We report Bemcentinib and Repotrectinib, formerly prescribed for cancer, as potential inhibitors of the CK1 δ. Besides their high binding affinity compared to ATP, they can inhibit all ATP-binding sites and alter the tau binding stability.Communicated by Ramaswamy H. Sarma.

Anaplastic lymphoma kinase inhibitors-a review of anticancer properties, clinical efficacy, and resistance mechanisms

Fusions and mutations of anaplastic lymphoma kinase (ALK), a tyrosine kinase receptor, have been identified in several neoplastic diseases. Rearranged ALK is a driver of tumorigenesis, which activates various signaling pathway associated with proliferation and survival. To date, several agents that target and inhibit ALK have been developed. The most studied ALK-positive disease is non-small cell lung cancer, and three generations of ALK tyrosine kinase inhibitors (TKIs) have been approved for the treatment of metastatic disease. Nevertheless, the use of ALK-TKIs is associated with acquired resistance (resistance mutations, bypass signaling), which leads to disease progression and may require a substitution or introduction of other treatment agents. Understanding of the complex nature and network of resistance mutations may allow to introduce sequential and targeted therapies. In this review, we aim to summarize the efficacy and safety profile of ALK inhibitors, describe off-target anticancer effects, and discuss resistance mechanisms in the context of personalized oncology.

Multifaceted Roles of ALK Family Receptors and Augmentor Ligands in Health and Disease: A Comprehensive Review

This review commemorates the 10-year anniversary of the discovery of physiological ligands Augα (Augmentor α; ALKAL2; Fam150b) and Augβ (Augmentor β; ALKAL1; Fam150a) for anaplastic lymphoma kinase (ALK) and leukocyte tyrosine kinase (LTK), previously considered orphan receptors. This manuscript provides an in-depth review of the biophysical and cellular properties of ALK family receptors and their roles in cancer, metabolism, pain, ophthalmology, pigmentation, central nervous system (CNS) function, and reproduction. ALK and LTK receptors are implicated in the development of numerous cancers, and targeted inhibition of their signaling pathways can offer therapeutic benefits. Additionally, ALK family receptors are involved in regulating body weight and metabolism, modulating pain signaling, and contributing to eye development and pigmentation. In the CNS, these receptors play a role in synapse modulation, neurogenesis, and various psychiatric pathologies. Lastly, ALK expression is linked to reproductive functions, with potential implications for patients undergoing ALK inhibitor therapy. Further research is needed to better understand the complex interactions of ALK family receptors and Aug ligands and to repurpose targeted therapy for a wide range of human diseases.

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.

Pyrazole-containing pharmaceuticals: target, pharmacological activity, and their SAR studies

Pyrazole is a five-membered heterocycle bearing two adjacent nitrogen atoms. Both pharmaceutical agents and natural products with pyrazole as a nucleus have exhibited a broad spectrum of biological activities. In the last few decades, more than 40 pyrazole-containing drugs have been approved by the FDA for the treatment of a broad range of clinical conditions including celecoxib (anti-inflammatory), CDPPB (antipsychotic), difenamizole (analgesic), etc. Owing to the unique physicochemical properties of the pyrazole core, pyrazole-containing drugs may exert better pharmacokinetics and pharmacological effects compared with drugs containing similar heterocyclic rings. The purpose of this paper is to provide an overview of all the existing drugs bearing a pyrazole nucleus that have been approved or in clinical trials, involving their pharmacological activities and SAR studies.

ATR inhibition enables complete tumour regression in ALK-driven NB mouse models

High-risk neuroblastoma (NB) often involves MYCN amplification as well as mutations in ALK. Currently, high-risk NB presents significant clinical challenges, and additional therapeutic options are needed. Oncogenes like MYCN and ALK result in increased replication stress in cancer cells, offering therapeutically exploitable options. We have pursued phosphoproteomic analyses highlighting ATR activity in ALK-driven NB cells, identifying the BAY1895344 ATR inhibitor as a potent inhibitor of NB cell growth and proliferation. Using RNA-Seq, proteomics and phosphoproteomics we characterize NB cell and tumour responses to ATR inhibition, identifying key components of the DNA damage response as ATR targets in NB cells. ATR inhibition also produces robust responses in mouse models. Remarkably, a 2-week combined ATR/ALK inhibition protocol leads to complete tumor regression in two independent genetically modified mouse NB models. These results suggest that NB patients, particularly in high-risk groups with oncogene-induced replication stress, may benefit from ATR inhibition as therapeutic intervention.

Effective therapeutic options are still needed in neuroblastoma treatment. Here, the authors, through a comprehensive proteomics analysis, identify ATR as a potential therapeutic target of neuroblastoma and demonstrate the efficacy of the ATR inhibitor BAY1895344 in combination with the ALK tyrosine kinase inhibitor lorlatinib.

Spatial and temporal intratumour heterogeneity has potential consequences for single biopsy-based neuroblastoma treatment decisions

Intratumour heterogeneity is a major cause of treatment failure in cancer. We present in-depth analyses combining transcriptomic and genomic profiling with ultra-deep targeted sequencing of multiregional biopsies in 10 patients with neuroblastoma, a devastating childhood tumour. We observe high spatial and temporal heterogeneity in somatic mutations and somatic copy-number alterations which are reflected on the transcriptomic level. Mutations in some druggable target genes including ALK and FGFR1 are heterogeneous at diagnosis and/or relapse, raising the issue whether current target prioritization and molecular risk stratification procedures in single biopsies are sufficiently reliable for therapy decisions. The genetic heterogeneity in gene mutations and chromosome aberrations observed in deep analyses from patient courses suggest clonal evolution before treatment and under treatment pressure, and support early emergence of metastatic clones and ongoing chromosomal instability during disease evolution. We report continuous clonal evolution on mutational and copy number levels in neuroblastoma, and detail its implications for therapy selection, risk stratification and therapy resistance.

ABCB1 and ABCG2 Control Brain Accumulation and Intestinal Disposition of the Novel ROS1/TRK/ALK Inhibitor Repotrectinib, While OATP1A/1B, ABCG2, and CYP3A Limit Its Oral Availability

Repotrectinib shows high activity against ROS1/TRK/ALK fusion-positive cancers in preclinical studies. We explored the roles of multidrug efflux transporters ABCB1 and ABCG2, the OATP1A/1B uptake transporter(s), and the CYP3A complex in pharmacokinetics and tissue distribution of repotrectinib in genetically modified mouse models. In vitro, human ABCB1 and ABCG2, and mouse Abcg2 efficiently transported repotrectinib with efflux transport ratios of 13.5, 5.6, and 40, respectively. Oral repotrectinib (10 mg/kg) showed higher plasma exposures in Abcg2-deficient mouse strains. Brain-to-plasma ratios were increased in Abcb1a/1b^−/− (4.1-fold) and Abcb1a/1b;Abcg2^−/− (14.2-fold) compared to wild-type mice, but not in single Abcg2^−/− mice. Small intestinal content recovery of repotrectinib was decreased 4.9-fold in Abcb1a/1b^−/− and 13.6-fold in Abcb1a/1b;Abcg2^−/− mice. Intriguingly, Abcb1a/1b;Abcg2^−/− mice displayed transient, mild, likely CNS-localized toxicity. Oatp1a/1b deficiency caused a 2.3-fold increased oral availability and corresponding decrease in liver distribution of repotrectinib. In Cyp3a^−/− mice, repotrectinib plasma AUC_0–h was 2.3-fold increased, and subsequently reduced 2.0-fold in humanized CYP3A4 transgenic mice. Collectively, Abcb1 and Abcg2 restrict repotrectinib brain accumulation and possibly toxicity, and control its intestinal disposition. Abcg2 also limits repotrectinib oral availability. Oatp1a/1b mediates repotrectinib liver uptake, thus reducing its systemic exposure. Systemic exposure of repotrectinib is also substantially limited by CYP3A activity. These insights may be useful to optimize the therapeutic application of repotrectinib.

Therapeutic Targeting of the Anaplastic Lymphoma Kinase (ALK) in Neuroblastoma-A Comprehensive Update

Neuroblastoma (NBL) is an embryonic malignancy of the sympathetic nervous system and mostly affects children under the age of five. NBL is highly heterogeneous and ranges from spontaneously regressing to highly aggressive disease. One of the risk factors for poor prognosis are aberrations in the receptor tyrosine kinase anaplastic lymphoma kinase (ALK), which is involved in the normal development and function of the nervous system. ALK mutations lead to constitutive activation of ALK and its downstream signalling pathways, thus driving tumorigenesis. A wide range of steric ALK inhibitors has been synthesized, and several of these inhibitors are already in clinical use. Major challenges are acquired drug resistance to steric inhibitors and pathway evasion strategies of cancer cells upon targeted therapy. This review will give a comprehensive overview on ALK inhibitors in clinical use in high-risk NBL and on the potential and limitations of novel inhibitors. Because combinatory treatment regimens are probably less likely to induce drug resistance, a special focus will be on the combination of ALK inhibitors with drugs that either target downstream signalling pathways or that affect the survival and proliferation of cancer cells in general.

Translational Strategies for Repotrectinib in Neuroblastoma

Limited clinical data are available regarding the utility of multikinase inhibition in neuroblastoma. Repotrectinib (TPX-0005) is a multikinase inhibitor that targets ALK, TRK, JAK2/STAT, and Src/FAK, which have all been implicated in the pathogenesis of neuroblastoma. We evaluated the preclinical activity of repotrectinib monotherapy and in combination with chemotherapy as a potential therapeutic approach for relapsed/refractory neuroblastoma. In vitro sensitivity to repotrectinib, ensartinib, and cytotoxic chemotherapy was evaluated in neuroblastoma cell lines. In vivo antitumor effect of repotrectinib monotherapy, and in combination with chemotherapy, was evaluated using a genotypically diverse cohort of patient-derived xenograft (PDX) models of neuroblastoma. Repotrectinib had comparable cytotoxic activity across cell lines irrespective of ALK mutational status. Combination with chemotherapy demonstrated increased antiproliferative activity across several cell lines. Repotrectinib monotherapy had notable antitumor activity and prolonged event-free survival compared with vehicle and ensartinib in PDX models (P < 0.05). Repotrectinib plus chemotherapy was superior to chemotherapy alone in ALK-mutant and ALK wild-type PDX models. These results demonstrate that repotrectinib has antitumor activity in genotypically diverse neuroblastoma models, and that combination of a multikinase inhibitor with chemotherapy may be a promising treatment paradigm for translation to the clinic.

Differential Impact of ALK Mutations in Neuroblastoma

PURPOSE

The tyrosine kinase receptor anaplastic lymphoma kinase (ALK) can be abnormally activated in neuroblastoma, and somatic ALK mutations occur in 6%-10% of patients. The differential clinical impact of these mutations has not been clearly elucidated.

METHODS

Data on patients with neuroblastoma harboring ALK mutations were retrospectively analyzed. ALK sequencing was performed by whole-genome sequencing, hybrid-based capture of targeted exomes, or hotspot ALK mutation profiling. The differential impact of ALK mutation site on clinical characteristics, response to treatment, and survival was analyzed. In a subgroup of patients with locoregional neuroblastoma diagnosed after 2014, the impact of all ALK mutations was compared with wild-type ALK.

RESULTS

Of 641 patients with neuroblastoma with ALK status analyzed on at least one tumor sample, 103 (16%) had tumors harboring ALK mutations. Mutations existed across all ages (birth to 67.8 years), stages (30% locoregional and 70% metastatic), and risk groups (20%, 11%, and 69% with low-, intermediate-, and high-risk disease, respectively). Mutation sites included F1174 (51%), R1275 (29%), R1245 (10%), and others (10%). Mutation site was not prognostic for progression-free survival or overall survival in the entire cohort, high-risk subgroup, or locoregional subgroup. Locoregional tumors with any ALK mutation were generally invasive: L2 by International Neuroblastoma Research Group staging in 30/31 patients with a 2-year progression-free survival (59%, 95% CI, 37.4 to 80.5) that was inferior to historical controls. This observation was corroborated in the post-2014 subgroup in which gross total resection was less likely for ALK-mutated tumors.

CONCLUSION

Somatic ALK mutations are present across all stages and risk groups of neuroblastoma. No specific mutation carries differential prognostic significance. Locoregional neuroblastoma has an invasive phenotype when harboring somatic ALK mutations in this population.

ALK ligand ALKAL2 potentiates MYCN-driven neuroblastoma in the absence of ALK mutation

High‐risk neuroblastoma (NB) is responsible for a disproportionate number of childhood deaths due to cancer. One indicator of high‐risk NB is amplification of the neural MYC (MYCN) oncogene, which is currently therapeutically intractable. Identification of anaplastic lymphoma kinase (ALK) as an NB oncogene raised the possibility of using ALK tyrosine kinase inhibitors (TKIs) in treatment of patients with activating ALK mutations. 8–10% of primary NB patients are ALK‐positive, a figure that increases in the relapsed population. ALK is activated by the ALKAL2 ligand located on chromosome 2p, along with ALK and MYCN, in the “2p‐gain” region associated with NB. Dysregulation of ALK ligand in NB has not been addressed, although one of the first oncogenes described was v‐sis that shares > 90% homology with PDGF. Therefore, we tested whether ALKAL2 ligand could potentiate NB progression in the absence of ALK mutation. We show that ALKAL2 overexpression in mice drives ALK TKI‐sensitive NB in the absence of ALK mutation, suggesting that additional NB patients, such as those exhibiting 2p‐gain, may benefit from ALK TKI‐based therapeutic intervention.

Emerging therapeutic targets for neuroblastoma

INTRODUCTION

Neuroblastoma (NB) is the prime cancer of infancy, and accounts for 9% of pediatric cancer deaths. While children diagnosed with clinically stable NB experience a complete cure, those with high-risk disease (HR-NB) do not recover, despite intensive therapeutic strategies. Development of novel and effective targeted therapies is needed to counter disease progression, and to benefit long-term survival of children with HR-NB.

AREAS COVERED

Recent studies (2017-2020) pertinent to NB evolution are selectively reviewed to recognize novel and effective therapeutic targets. The prospective and promising therapeutic targets/strategies for HR-NB are categorized into (a) targeting oncogene-like and/or reinforcing tumor suppressor (TS)-like lncRNAs; (b) targeting oncogene-like microRNAs (miRs) and/or mimicking TS-miRs; (c) targets for immunotherapy; (d) targeting epithelial-to-mesenchymal transition and cancer stem cells; (e) novel and beneficial combination approaches; and (f) repurposing drugs and other strategies in development.

EXPERT OPINION

It is highly unlikely that agents targeting a single candidate or signaling will be beneficial for an HR-NB cure. We must develop efficient drug deliverables for functional targets, which could be integrated and advance clinical therapy. Fittingly, the looming evidence indicated an aggressive evolution of promising novel and integrative targets, development of efficient drugs, and improvised strategies for HR-NB treatment.