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.

• Keywords
• ABC transporter, cytochrome P450, encorafenib, multidrug resistance, non-small cell lung cancer,
• Publication type
• Journal Article MeSH

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.

• Keywords
• ABC transporter, cytochrome P450, multidrug resistance, pharmacokinetic drug–drug interaction, small cell lung cancer, talazoparib,
• MeSH
• ATP Binding Cassette Transporter, Subfamily G, Member 2 genetics   MeSH
• ATP-Binding Cassette Transporters genetics   metabolism   MeSH
• Humans MeSH
• Drug Resistance, Multiple MeSH
• Neoplasm Proteins metabolism   MeSH
• Lung Neoplasms * MeSH
• Carcinoma, Non-Small-Cell Lung * drug therapy   genetics   MeSH
• ATP Binding Cassette Transporter, Subfamily B genetics   MeSH
• Cytochrome P-450 Enzyme System metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• ATP Binding Cassette Transporter, Subfamily G, Member 2 MeSH
• ATP-Binding Cassette Transporters MeSH
• ABCB1 protein, human MeSH Browser
• ABCG2 protein, human MeSH Browser
• Neoplasm Proteins MeSH
• ATP Binding Cassette Transporter, Subfamily B MeSH
• Cytochrome P-450 Enzyme System MeSH
• talazoparib MeSH Browser

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.

• Keywords
• ABC transporter, cytochrome P450, drug interaction, multidrug resistance, non-small cell lung cancer, tepotinib,
• MeSH
• ATP-Binding Cassette Transporters antagonists & inhibitors   MeSH
• Drug Resistance, Neoplasm drug effects   MeSH
• Cytostatic Agents pharmacology   MeSH
• Drug Interactions * MeSH
• Humans MeSH
• Drug Resistance, Multiple drug effects   MeSH
• Lung Neoplasms drug therapy   metabolism   pathology   MeSH
• Carcinoma, Non-Small-Cell Lung drug therapy   metabolism   pathology   MeSH
• Piperidines pharmacology   MeSH
• Antineoplastic Agents pharmacology   MeSH
• Pyridazines pharmacology   MeSH
• Pyrimidines pharmacology   MeSH
• In Vitro Techniques MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• ATP-Binding Cassette Transporters MeSH
• Cytostatic Agents MeSH
• Piperidines MeSH
• Antineoplastic Agents MeSH
• Pyridazines MeSH
• Pyrimidines MeSH
• tepotinib MeSH Browser