Entrectinib reverses cytostatic resistance through the inhibition of ABCB1 efflux transporter, but not the CYP3A4 drug-metabolizing enzyme

Non-kinase off-target inhibitory activities of clinically-relevant kinase inhibitors

Protein kinases are responsible for a myriad of cellular functions, such as cell cycle, apoptosis, and proliferation. Because of this, kinases make excellent targets for therapeutics. During the process to identify clinical kinase inhibitor candidates, kinase selectivity profiles of lead inhibitors are typically obtained. Such kinome selectivity screening could identify crucial kinase anti-targets that might contribute to drug toxicity and/or reveal additional kinase targets that potentially contribute to the efficacy of the compound via kinase polypharmacology. In addition to kinome panel screening, practitioners also obtain the inhibition profiles of a few non-kinase targets, such as ion-channels and select GPCR targets to identify compounds that might possess potential liabilities. Often ignored is the possibility that identified kinase inhibitors might also inhibit or bind to the other proteins (greater than 20,000) in the cell that are not kinases, which may be relevant to toxicity or even additional mode of drug action. This review highlights various inhibitors, which have been approved by the FDA or are currently undergoing clinical trials, that also inhibit other non-kinase targets. The binding poses of the drugs in the binding sites of the target kinases and off-targets are analyzed to understand if the same features of the compounds are critical for the polypharmacology.

Advances in Drug Therapy for Gastrointestinal Stromal Tumour

INTRODUCTION

Gastrointestinal stromal tumour (GIST) is a common gastrointestinal sarcoma located in the stromal cells of the digestive tract, and molecular studies have revealed the pathogenesis of mutations in KIT and PDGFRA genes. Since imatinib opened the era of targeted therapy for GIST, tyrosine kinase inhibitors (TKIs) that can treat GIST have been developed successively. However, the lack of new drugs with satisfactory therapeutic standards has made addressing resistance a significant challenge for TKIs in the face of the resistance to first-line and second-line drugs. Therefore, we need to find as many drugs and new treatments that block mutated genes as possible.

METHODS

We conducted a comprehensive collection of literature using databases, integrated and analysed the selected literature based on keywords and the comprehensive nature of the articles, and finally wrote articles based on the content of the studies.

RESULTS

In this article, we first briefly explained the relationship between GIST and KIT/ PDGFRα and then introduced the related drug treatment. The research progress of TKIs was analyzed according to the resistance of the drugs.

CONCLUSION

This article describes the research progress of some TKIs and briefly introduces the currently approved TKIs and some drugs under investigation that may have better therapeutic effects, hoping to provide clues to the research of new drugs.

Perspectives on drug repurposing to overcome cancer multidrug resistance mediated by ABCB1 and ABCG2

The overexpression of the human ATP-binding cassette (ABC) transporters in cancer cells is a common mechanism involved in developing multidrug resistance (MDR). Unfortunately, there are currently no approved drugs specifically designed to treat multidrug-resistant cancers, making MDR a significant obstacle to successful chemotherapy. Despite over two decades of research, developing transporter-specific inhibitors for clinical use has proven to be a challenging endeavor. As an alternative approach, drug repurposing has gained traction as a more practical method to discover clinically effective modulators of drug transporters. This involves exploring new indications for already-approved drugs, bypassing the lengthy process of developing novel synthetic inhibitors. In this context, we will discuss the mechanisms of ABC drug transporters ABCB1 and ABCG2, their roles in cancer MDR, and the inhibitors that have been evaluated for their potential to reverse MDR mediated by these drug transporters. Our focus will be on providing an up-to-date report on approved drugs tested for their inhibitory activities against these drug efflux pumps. Lastly, we will explore the challenges and prospects of repurposing already approved medications for clinical use to overcome chemoresistance in patients with high tumor expression of ABCB1 and/or ABCG2.

Tazemetostat synergistically combats multidrug resistance by the unique triple inhibition of ABCB1, ABCC1, and ABCG2 efflux transporters in vitro and ex vivo

ATP-binding cassette (ABC) drug efflux transporters and drug metabolizing enzymes play crucial roles in pharmacokinetic drug-drug interactions and multidrug tumor resistance (MDR). Tazemetostat (EPZ-6438, Tazverik) is a novel epigenetic drug that has been recently approved for the therapy of advanced epithelioid sarcoma and follicular lymphoma. Additionally, this medication is currently being clinically tested to treat several other cancers such as non-small cell lung cancer (NSCLC). This study aimed to investigate the inhibitory effects of tazemetostat on selected ABC transporters/cytochrome P450 3A4 (CYP3A4) enzyme to comprehensively explore its role in MDR. First, our accumulation and molecular docking studies showed that tazemetostat is a unique triple inhibitor of ABCB1, ABCC1, and ABCG2 transporters. In contrast, tazemetostat exhibited only low level of interaction with the CYP3A4 isozyme. Drug combination assays confirmed that tazemetostat is a multipotent MDR modulator able to synergize with various conventional chemotherapeutics in vitro. Subsequent caspase activity assays and microscopic staining of apoptotic nuclei proved that the effective induction of apoptosis is behind the observed synergies. Notably, a potent MDR-modulatory capacity of tazemetostat was recorded in primary ex vivo NSCLC explants generated from patients' biopsies. On the contrary, its possible position of pharmacokinetic MDR's victim was excluded in comparative proliferation assays. Finally, tested drug has not been identified as an inducer of resistant phenotype in NSCLC cell lines. In conclusion, we demonstrated that tazemetostat is a unique multispecific chemosensitizer, which has strong potential to overcome limitations seen in the era of traditional MDR modulators.

Encorafenib Acts as a Dual-Activity Chemosensitizer through Its Inhibitory Effect on ABCC1 Transporter In Vitro and Ex Vivo

Encorafenib (LGX818, trade name Braftovi), a novel BRAF inhibitor, has been approved for the treatment of melanoma and colorectal cancer. In the present work, we evaluated encorafenib's possible antagonistic effects on the pharmacokinetic mechanisms of multidrug resistance (MDR), as well as its perpetrator role in drug interactions. Firstly, encorafenib potently inhibited the efflux function of the ABCC1 transporter in drug accumulation assays, while moderate and null interaction levels were recorded for ABCB1 and ABCG2, respectively. In contrast, the mRNA expression levels of all the tested transporters were not altered by encorafenib. In the drug combination studies, we found that daunorubicin and topotecan resistances were synergistically attenuated by the encorafenib-mediated interaction in A431-ABCC1 cells. Notably, further experiments in ex vivo patient-derived explants confirmed the MDR-modulating ability of encorafenib. Advantageously, the overexpression of tested drug efflux transporters failed to hinder the antiproliferative activity of encorafenib. In addition, no significant modulation of the CYP3A4 enzyme's activity by encorafenib was observed. In conclusion, our work indicated that encorafenib can act as an effective chemosensitizer targeting the ABCC1-induced MDR. Our in vitro and ex vivo data might provide valuable information for designing the novel effective scheme applicable in the clinical pharmacotherapy of BRAF-mutated/ABCC1-expressing tumors.

Talazoparib Does Not Interact with ABCB1 Transporter or Cytochrome P450s, but Modulates Multidrug Resistance Mediated by ABCC1 and ABCG2: An in Vitro and Ex Vivo Study

Talazoparib (Talzenna) is a novel poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitor that is clinically used for the therapy of breast cancer. Furthermore, the drug has shown antitumor activity against different cancer types, including non-small cell lung cancer (NSCLC). In this work, we investigated the possible inhibitory interactions of talazoparib toward selected ATP-binding cassette (ABC) drug efflux transporters and cytochrome P450 biotransformation enzymes (CYPs) and evaluated its position in multidrug resistance (MDR). In accumulation studies, talazoparib interacted with the ABCC1 and ABCG2 transporters, but there were no significant effects on ABCB1. Furthermore, incubation assays revealed a negligible capacity of the tested drug to inhibit clinically relevant CYPs. In in vitro drug combination experiments, talazoparib synergistically reversed daunorubicin and mitoxantrone resistance in cells with ABCC1 and ABCG2 expression, respectively. Importantly, the position of an effective MDR modulator was further confirmed in drug combinations performed in ex vivo NSCLC patients-derived explants, whereas the possible victim role was refuted in comparative proliferation experiments. In addition, talazoparib had no significant effects on the mRNA-level expressions of MDR-related ABC transporters in the MCF-7 cellular model. In summary, our study presents a comprehensive overview on the pharmacokinetic drug-drug interactions (DDI) profile of talazoparib. Moreover, we introduced talazoparib as an efficient MDR antagonist.

Mahanimbine isolated from Murraya koenigii inhibits P-glycoprotein involved in lung cancer chemoresistance

P-glycoprotein (P-gp), a transmembrane glycoprotein, is mainly involved in lung cancer multidrug resistance. Several P-gp inhibitors have been developed to enhance the efficacy of chemotherapeutics and overcome drug resistance. However, most of them failed in the clinical stages due to undesirable side effects. Therefore, there is a requirement to develop P-gp inhibitors from natural sources. Dietary spice bioactives have been well-known for their anticancer activities. However, their role in modulating the P-gp activity has not been well investigated. Therefore, we have screened for the potential bioactives from various spice plants with P-gp modulatory activity using computational molecular docking analysis. The computational analysis revealed several key bioactives from curry leaves, specifically mahanimbine, exhibited a strong binding affinity with P-gp. Unfortunately, mahanimbine is available with few commercial sources at very high prices. Therefore, we prepared a curry leaves extract and isolated mahanimbine by a novel, yet simple, extraction method that requires less time and causes minimum environmental hazards. After purification, structure, and mass were confirmed for the isolated compound by IR spectrum and LC-MS/MS analysis, respectively. In the mechanistic study, hydrolysis of ATP and substrate efflux by P-gp are coupled. Hence, ATP binding at the ATPase-binding site is one of the fundamental steps for the P-gp efflux cycle. We found that mahanimbine demonstrated to stimulate P-gp ATPase activity. Concurrently, it enhanced the intracellular accumulation of P-gp substrates Rhodamine 123 and Hoechst stain, which indicates that mahanimbine modulates the function of P-gp. In addition, we have analyzed the complementary effect of mahanimbine with the chemotherapeutic drug gefitinib. We found that mahanimbine synergistically enhanced gefitinib efficiency by increasing its intracellular accumulation in lung cancer cells. Overall, mahanimbine has been shown to be a potent P-gp modulator. Therefore, mahanimbine can be further developed as a potential candidate to overcome chemoresistance in lung cancer.

Role of Drug Transporters in Elucidating Inter-Individual Variability in Pediatric Chemotherapy-Related Toxicities and Response

Pediatric cancer treatment has evolved significantly in recent decades. The implementation of risk stratification strategies and the selection of evidence-based chemotherapy combinations have improved survival outcomes. However, there is large interindividual variability in terms of chemotherapy-related toxicities and, sometimes, the response among this population. This variability is partly attributed to the functional variability of drug-metabolizing enzymes (DME) and drug transporters (DTS) involved in the process of absorption, distribution, metabolism and excretion (ADME). The DTS, being ubiquitous, affects drug disposition across membranes and has relevance in determining chemotherapy response in pediatric cancer patients. Among the factors affecting DTS function, ontogeny or maturation is important in the pediatric population. In this narrative review, we describe the role of drug uptake/efflux transporters in defining pediatric chemotherapy-treatment-related toxicities and responses. Developmental differences in DTS and the consequent implications are also briefly discussed for the most commonly used chemotherapeutic drugs in the pediatric population.

A curated binary pattern multitarget dataset of focused ATP-binding cassette transporter inhibitors

Multitarget datasets that correlate bioactivity landscapes of small-molecules toward different related or unrelated pharmacological targets are crucial for novel drug design and discovery. ATP-binding cassette (ABC) transporters are critical membrane-bound transport proteins that impact drug and metabolite distribution in human disease as well as disease diagnosis and therapy. Molecular-structural patterns are of the highest importance for the drug discovery process as demonstrated by the novel drug discovery tool ‘computer-aided pattern analysis’ (‘C@PA’). Here, we report a multitarget dataset of 1,167 ABC transporter inhibitors analyzed for 604 molecular substructures in a statistical binary pattern distribution scheme. This binary pattern multitarget dataset (ABC_BPMDS) can be utilized for various areas. These areas include the intended design of (i) polypharmacological agents, (ii) highly potent and selective ABC transporter-targeting agents, but also (iii) agents that avoid clearance by the focused ABC transporters [e.g., at the blood-brain barrier (BBB)]. The information provided will not only facilitate novel drug prediction and discovery of ABC transporter-targeting agents, but also drug design in general in terms of pharmacokinetics and pharmacodynamics.

Measurement(s)	Influx • Efflux • Tracer • Transport velocity
Technology Type(s)	Fluorometry • Radioactivity • Plate reader • Flow cytometer • Tracer distribution
Factor Type(s)	half-maximal inhibition concentration
Sample Characteristic - Organism	Homo sapiens
Sample Characteristic - Environment	cell culture
Sample Characteristic - Location	Kingdom of Norway • Germany • Australia • Latvia

Lapatinib Suppresses HER2-Overexpressed Cholangiocarcinoma and Overcomes ABCB1- Mediated Gemcitabine Chemoresistance

Background

Recent breakthroughs in cholangiocarcinoma (CCA) genomics have led to the discovery of many unique identifying mutations, of which HER2 has been found to be overexpressed specifically in cases of extrahepatic CCA. However, whether or not lapatinib (an oral tyrosine kinase inhibitor selective for inhibition of HER2), or a combination of lapatinib and gemcitabine, exerts inhibitory effects on HER2-overexpressed CCA is still unclear.

Methods

The effect of lapatinib and a lapatinib-gemcitabine combination treatment on CCA was determined using organoid and cell line models. Cell cycle arrest, apoptosis and proteins involving HER2-dependent downstream signaling pathways were analyzed to assess the effect of lapatinib on HER2⁺ CCA. The synergistic effect of lapatinib and gemcitabine was interpreted by docking analysis, ABCB1-associated ATPase assay, rhodamine transport assay and LC-MS/MS analyses.

Results

dFdCTP, the active metabolite of gemcitabine, is proved to be the substrate of ABCB1 by docking analysis and ATPase assay. The upregulation of ABCB1 after gemcitabine treatment accounts for the resistance of gemcitabine. Lapatinib exerts a dual effect on HER2-overexpressed CCA, suppressing the growth of CCA cells by inhibiting HER2 and HER2-dependent downstream signaling pathways while inhibiting ABCB1 transporter function, allowing for the accumulation of active gemcitabine metabolites within cells.

Conclusions

Our data demonstrates that lapatinib can not only inhibit growth of CCA overexpressing HER2, but can also circumvent ABCB1-mediated chemoresistance after gemcitabine treatment. As such, this provides a preclinical rationale basis for further clinical investigation into the effectiveness of a combination treatment of lapatinib with gemcitabine in HER2-overexpressed CCA.

Sonidegib potentiates the cancer cells' sensitivity to cytostatic agents by functional inhibition of ABCB1 and ABCG2 in vitro and ex vivo

Sonidegib (LDE-225) is a Hedgehog pathway inhibitor used for the therapy of basal cell carcinoma. In addition, the drug is a subject of clinical trials for the treatment of other solid tumors including non-small cell lung cancer (NSCLC). In this study, we explored the potential of sonidegib to act as a perpetrator of drug-drug interactions (DDIs) and modulator of transporter- and enzyme-mediated multidrug resistance (MDR). First, we found that transport functions of ABCB1 and ABCG2 were effectively inhibited by sonidegib in accumulation studies. In contrast, the drug did not cause fluctuations in mRNA levels of tested efflux transporters. In drug combination assays, sonidegib synergistically enhanced the cytotoxicity of daunorubicin and mitoxantrone in ABCB1- and ABCG2-overexpressing cells, respectively. Notably, similar phenomena were also observed in explant tumor cultures derived from NSCLC-suffering patients. In addition, the anticancer effects of sonidegib were not hampered by the expression of the ABC transporters associated with MDR. Last, sonidegib had no significant influence on the activity of CYP3A4 isoform in vitro. In summary, our work suggests that sonidegib can be considered a potential perpetrator of clinical DDIs on ABCB1 and ABCG2. After in vivo evaluation, its chemosensitizing properties might be projected into efficient and safe treatment regimen for the clinical management of NSCLC patients with high ABCB1/ABCG2 expression.

Alisertib shows negligible potential for perpetrating pharmacokinetic drug-drug interactions on ABCB1, ABCG2 and cytochromes P450, but acts as dual-activity resistance modulator through the inhibition of ABCC1 transporter

Alisertib (MLN8237), a novel Aurora A kinase inhibitor, is currently being clinically tested in late-phase trials for the therapy of various malignancies. In the present work, we describe alisertib's potential to perpetrate pharmacokinetic drug-drug interactions (DDIs) and/or to act as an antagonist of multidrug resistance (MDR). In accumulation assays, alisertib potently inhibited ABCC1 transporter, but not ABCB1 or ABCG2. The results of molecular modeling suggested a bifunctional mechanism for interaction on ABCC1. In addition, alisertib was characterized as a low- to moderate-affinity inhibitor of recombinant CYP3A4, CYP2C8, CYP2C9, CYP2C19, and CYP2D6 isoenzymes, but without potential clinical relevance. Drug combination studies revealed the capability of alisertib to synergistically antagonize ABCC1-mediated resistance to daunorubicin. Although alisertib exhibited substrate characteristics toward ABCB1 transporter in monolayer transport assays, comparative proliferation studies showed lack of its MDR-victim behavior in cells overexpressing ABCB1 as well as ABCG2 and ABCC1. Lastly, alisertib did not affect the expression of ABCC1, ABCG2, ABCB1 transporters and CYP1A2, CYP3A4, CYP2B6 isozymes on mRNA level in various systemic and tumoral models. In conclusion, our study suggests that alisertib is a drug candidate with negligible potential for perpetrating systemic pharmacokinetic DDIs on ABCB1, ABCG2 and cytochromes P450. In addition, we introduce alisertib as an effective dual-activity chemosensitizer whose MDR-antagonistic capacities are not impaired by efflux or effect on MDR phenotype. Our in vitro findings provide important pieces of information for clinicians when introducing alisertib into the clinical area.

Dabrafenib inhibits ABCG2 and cytochrome P450 isoenzymes; potential implications for combination anticancer therapy

Dabrafenib is a BRAF inhibitor used in combination treatment of malignant melanoma and non-small cell lung carcinoma. In this study, we aimed to characterize its interactions with cytochrome P450 (CYP) isoenzymes and ATP-binding cassette (ABC) efflux transporters that have critical impact on the pharmacokinetics of drugs and play a role in drug resistance development. Using accumulation assays, we showed that dabrafenib inhibited ABCG2 and, less potently, ABCB1 transporter. We also confirmed dabrafenib as a CYP2C8, CYP2C9, CYP3A4, and CYP3A5 inhibitor. Importantly, inhibition of ABCG2 and CYP3A4 by dabrafenib led to the potentiation of cytotoxic effects of mitoxantrone and docetaxel toward respective resistant cell lines in drug combination studies. On the contrary, the synergistic effect was not consistently observed in ABCB1-expressing models. We further demonstrated that mRNA levels of ABCB1, ABCG2, ABCC1, and CYP3A4 were increased after 24 h and 48 h exposure to dabrafenib. Overall, our data confirm dabrafenib as a drug frequently and potently interacting with ABC transporters and CYP isoenzymes. This feature should be addressed with caution when administering dabrafenib to patients with polypharmacy but also could be utilized advantageously when designing new dabrafenib-containing drug combinations to improve the therapeutic outcome in drug-resistant cancer.

Tepotinib Inhibits Several Drug Efflux Transporters and Biotransformation Enzymes: The Role in Drug-Drug Interactions and Targeting Cytostatic Resistance In Vitro and Ex Vivo

Tepotinib is a novel tyrosine kinase inhibitor recently approved for the treatment of non-small cell lung cancer (NSCLC). In this study, we evaluated the tepotinib's potential to perpetrate pharmacokinetic drug interactions and modulate multidrug resistance (MDR). Accumulation studies showed that tepotinib potently inhibits ABCB1 and ABCG2 efflux transporters, which was confirmed by molecular docking. In addition, tepotinib inhibited several recombinant cytochrome P450 (CYP) isoforms with varying potency. In subsequent drug combination experiments, tepotinib synergistically reversed daunorubicin and mitoxantrone resistance in cells with ABCB1 and ABCG2 overexpression, respectively. Remarkably, MDR-modulatory properties were confirmed in ex vivo explants derived from NSCLC patients. Furthermore, we demonstrated that anticancer effect of tepotinib is not influenced by the presence of ABC transporters associated with MDR, although monolayer transport assays designated it as ABCB1 substrate. Finally, tested drug was observed to have negligible effect on the expression of clinically relevant drug efflux transporters and CYP enzymes. In conclusion, our findings provide complex overview on the tepotinib's drug interaction profile and suggest a promising novel therapeutic strategy for future clinical investigations.

Roles of CYP3A4, CYP3A5 and CYP2C8 drug-metabolizing enzymes in cellular cytostatic resistance

Metabolic deactivation by cytochrome P450 (CYP) is considered a potential mechanism of anticancer drug resistance. However, this hypothesis is predominantly based on indirect pieces of evidence and/or is influenced by interfering factors such as the use of multienzymatic models. Thus, an experimental approach for its verification is needed. In the present work, we employed HepG2 cells transduced with CYP enzymes involved in docetaxel, paclitaxel and vincristine metabolism to provide mechanistic evidence on their possible roles in resistance to these chemotherapeutic agents. Using MTT proliferation tests, we showed that overexpression of CYP3A4 resulted in decreased antiproliferative activity of 1 μM docetaxel (by 11.2, 23.2 and 22.9% at 24, 48 and 72 h intervals, respectively), while the sensitivity of CYP3A4-transduced cells was restored by co-administration of ketoconazole. Paclitaxel exhibited differential efficacy in CYP2C8- and empty vector-transduced cells (significant differences between 10.9 and 24.4% for 0.01, 0.1 and 1 μM concentrations), but neither montelukast nor clotrimazole was capable of affecting this asymmetry. Finally, the pharmacological activity of vincristine was not influenced by CYP3A4 or CYP3A5 overexpression. In the follow-up caspase activation assays, docetaxel was confirmed to be a victim of CYP3A4-mediated resistance, which is, at least partly, brought by impaired activation of caspases 3/7, 8 and 9. In summary, our data demonstrate that CYP3A4-mediated metabolic deactivation of docetaxel might represent a significant mechanism of pharmacokinetic resistance to this drug. In contrast, the possible role of CYPs in resistance to paclitaxel and vincristine has been disconfirmed. Importantly, the expression of CYP3A4 in HepG2_CYP3A4 cells is comparable to that in primary hepatocytes and HepaRG cells, which suggests that our results might be relevant for in vivo conditions, e.g., for hepatocellular carcinoma. Thus, our data may serve as a valuable in vitro background for future in vivo studies exploring the area of intratumoural metabolism-based drug resistance.

Oral peptide delivery: challenges and the way ahead

Peptides and proteins have emerged as potential therapeutic agents and, in the search for the best treatment regimen, the oral route has been extensively evaluated because of its non-invasive and safe nature. The physicochemical properties of peptides and proteins along with the hurdles in the gastrointestinal tract (GIT), such as degrading enzymes and permeation barriers, are challenges to their delivery. To address these challenges, several conventional and novel approaches, such as nanocarriers, site-specific and stimuli specific delivery, are being used. In this review, we discuss the challenges to the oral delivery of peptides and the approaches used to tackle these challenges.