A phase Ib study of Oraxol (oral paclitaxel and encequidar) in patients with advanced malignancies

Evaluation of Encequidar as An Intestinal P-gp and BCRP Specific Inhibitor to Assess the Role of Intestinal P-gp and BCRP in Drug-Drug Interactions

PURPOSE

The differences between intestinal and systemic (hepatic and renal) P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) roles in drug disposition are difficult to define. Accordingly, we characterized Encequidar (ECD) as an intestinal P-gp and BCRP specific inhibitor to evaluate their role in drug disposition.

METHODS

We assessed the in vitro and in vivo inhibition potential of ECD towards human and animal P-gp and BCRP.

RESULTS

ECD is a potent inhibitor with a high degree of selectivity in inhibiting human P-gp (hP-gp) over human BCRP (hBCRP) (IC50s of 0.0058 ± 0.0006 vs. > 10 µM, respectively). In contrast, ECD is a potent inhibitor of rat and cynomolgus monkey BCRP (IC50 ranged from 0.059 to 0.18 µM). While the AUC of IV paclitaxel (PTX) was significantly increased by elacridar (ELD) (P < 0.05) but not ECD in rats (15 mg/kg; PO) (2.55- vs. 0.93-fold), that of PO PTX was significantly elevated to a similar extent between the inhibitors (39.5- vs. 33.5-fold). Similarly, the AUC of PO sulfasalazine (SFZ) was dramatically increased by ELD and ECD (16.6- vs. 3.04-fold) although that of IV SFZ was not significantly affected by ELD and ECD in rats (1.18- vs. 1.06-fold). Finally, a comparable ECD-induced increase of the AUC of PO talinolol in cynomolgus monkeys was observed compared with ELD (2.14- vs. 2.12-fold).

CONCLUSIONS

ECD may allow an in-depth appraisal of the role of intestinal efflux transporter(s) in drug disposition in animals and humans through local intestinal drug interactions.

Chemotherapeutic properties and side-effects associated with the clinical practice of terpene alkaloids: paclitaxel, docetaxel, and cabazitaxel

Over the years, many biological and synthetic agents have been explored and tested in attempts to halt the spread of cancer and/or cure it. Currently, several natural compounds have and are being considered in this regard. For example, paclitaxel is a potent anticancer drug that originates from the tree Taxus brevifolia. Paclitaxel has several derivatives, namely, docetaxel and cabazitaxel. These agents work by disrupting microtubule assembling dynamics and inducing cell cycle arrest at the G2/M phase of the cell cycle, ultimately triggering apoptosis. Such features have helped to establish paclitaxel as an authoritative therapeutic compound against neoplastic disorders. After the completion of compound (hemi) synthesis, this drug received approval for the treatment of solid tumors either alone or in combination with other agents. In this review, we explore the mechanisms of action of paclitaxel and its derivatives, the different formulations available, as well as the molecular pathways of cancer resistance, potential risks, and other therapeutic applications. In addition, the role of paclitaxel in hematological malignancies is explored, and potential limitations in the therapeutic use of paclitaxel at the clinical level are examined. Furthermore, paclitaxel is known to cause increased antigen presentation. The immunomodulatory potential of taxanes, alone or in combination with other pharmacologic agents, is explored. Despite terpene-alkaloids derivatives' anti-mitotic potential, the impact of this class of drugs on other oncogenic pathways, such as epithelial-to-mesenchymal transition and the epigenetic modulation of the transcription profile of cancer cells, is also analyzed, shedding light on potential future chemotherapeutic approaches to cancer.

The effect and mechanistic study of encequidar on reversing the resistance of SW620/AD300 cells to doxorubicin

Encequidar, a gut-specific P-glycoprotein (P-gp) inhibitor, makes oral paclitaxel possible, and has been used in clinical treatment of metastatic breast cancer, however, its pharmacological effect and mechanism of reversal of drug resistance in drug-resistant colon cancer cells SW620/AD300 are still unknown. Herein, we first synthesized encequidar and demonstrated that it could inhibit the transport activity of P-gp, reduced doxorubicin (DOX) efflux, enhanced DOX cytotoxicity and promoted tumor-apoptosis in SW620/AD300 cells. Metabolomic analysis of cell samples was performedusing liquid chromatography Q-Exactive mass spectrometer, the results of metabolite enrichment analysis and pathway analysis showed that the combination of encequidar and DOX could: i) significantly affect the citric acid cycle (TCA cycle) and reduce the energy supply required for P-gp to exert its transport activity; ii) affect the metabolism of glutathione, which is the main component of the anti-oxidative stress system, and reduce the ability of cells to resist oxidative stress; iii) increase the intracellular reactive oxygen species (ROS) production and enhance ROS-induced cell damage and lipid peroxidation, which in turn restore the sensitivity of drug-resistant cells to DOX. In conclusion, these results provide sufficient data support for the therapeutical application of the P-gp inhibitor encequidar to reverse MDR, and are of great significance to further understand the therapeutic advantages of encequidar in anti-tumor therapy and guide clinical rational drug use.

A commentary on the use of pharmacoenhancers in the pharmaceutical industry and the implication for DMPK drug discovery strategies

Paxlovid, a drug combining nirmatrelvir and ritonavir, was designed for the treatment of COVID-19 and its rapid development has led to emergency use approval by the FDA to reduce the impact of COVID-19 infection on patients.In order to overcome potentially suboptimal therapeutic exposures, nirmatrelvir is dosed in combination with ritonavir to boost the pharmacokinetics of the active product.Here we consider examples of drugs co-administered with pharmacoenhancers.Pharmacoenhancers have been adopted for multiple purposes such as ensuring therapeutic exposure of the active product, reducing formation of toxic metabolites, changing the route of administration, and increasing the cost-effectiveness of a therapy.We weigh the benefits and risks of this approach, examining the impact of technology developments on drug design and how enhanced integration between cross-discipline teams can improve the outcome of drug discovery.