Involvement of Transporters in Intestinal Drug-Drug Interactions of Oral Targeted Anticancer Drugs Assessed by Changes in Drug Absorption Time

Drug-drug interaction between letermovir and ciclosporin in allogeneic haematopoietic cell transplantation recipients

OBJECTIVES

Letermovir, a cytomegalovirus prophylactic agent, is widely used in allogeneic HSCT recipients. As an inhibitor of cytochrome P450 3A4 (CYP3A4) and P-glycoprotein (P-gp), it may interact with ciclosporin A (CsA), potentially impacting its pharmacokinetics. Inflammation can impair CYP3A-mediated drug metabolism, with severe inflammation reducing CsA metabolism. However, current data on the drug-drug interaction (DDI) between CsA and letermovir as a perpetrator are limited to healthy volunteers and lack evaluation in HSCT patients, particularly under minimal inflammation conditions, where such DDIs may occur.

METHODS

This retrospective, observational, single-centre study included seven adult HSCT recipients who received CsA and letermovir concurrently with no-to-mild inflammation (C-reactive protein  ≤40 mg/L). CsA concentration/dose (C/D) ratios were calculated before and after letermovir initiation. Changes in CsA pharmacokinetics were analysed using Wilcoxon signed-rank tests.

RESULTS

A 240 mg dose of letermovir once daily significantly increased the median CsA C/D ratio from 0.39 to 0.90 (P = 0.0156) and the median CsA trough concentration from 136 µg/L to 240 µg/L (P = 0.0156). These changes were attributed to CYP3A4 inhibition by letermovir, given the stable no-to-mild inflammatory status and the lack of additional DDI.

CONCLUSION

Letermovir significantly decreased CsA metabolism in HSCT patients through CYP3A4 inhibition, with clinical implications for dosing precision. Close therapeutic drug monitoring (generally twice weekly) is therefore recommended during letermovir initiation and discontinuation to mitigate risks of subtherapeutic levels or toxicity. This study highlights the significance of assessing DDIs in HSCT, where inflammation modulates metabolic interactions resulting in a complex interplay such as a disease-drug-drug interaction (D-DDI).

The ABCG2 protein in vitro transports the xenobiotic thiabendazole and increases the appearance of its residues in milk

Thiabendazole (TBZ) is a broad-spectrum anthelmintic and fungicide used in humans, animals, and agricultural commodities. TBZ residues are present in crops and animal products, including milk, posing a risk to food safety and public health. ABCG2 is a membrane transporter which affects bioavailability and milk secretion of xenobiotics. Therefore, the aim of this work was to characterize the role of ABCG2 in the in vitro transport and secretion into milk of 5-hydroxythiabendazole (5OH-TBZ), the main TBZ metabolite. Using MDCK-II polarized cells transduced with several species variants of ABCG2, we first demonstrated that 5OH-TBZ is efficiently in vitro transported by ABCG2. Subsequently, using Abcg2 knockout mice, we demonstrated that 5OH-TBZ secretion into milk was affected by Abcg2, with a more than 2-fold higher milk concentration and milk to plasma ratio in wild-type mice compared to their Abcg2-/- counterpart.

Enhanced In Vitro and In Vivo Anticancer Activity Through the Development of Sunitinib-Loaded Nanoniosomes with Controlled Release and Improved Uptake

This study aims to develop sunitinib niosomal formulations and assess their in-vitro anti-cancer efficiency against lung cancer cell line, A549. Sunitinib, a highly effective anticancer drug, was loaded in the niosome with high encapsulation efficiency. Collagen was coated on the surface of the niosome for enhanced cellular uptake and prolonged circulation time. Different formulations were produced, while response surface methodology was utilized to optimize the formulations. The stability of the formulations was evaluated over a 2-month period, revealing the importance of collagen coating. MTT assay demonstrated dose-dependent cytotoxicity for all formulations against lung cancer cells. Scratch assay test suggested antiproliferative efficacy of the formulations. The flow cytometry data confirmed the improved cytotoxicity with enhanced apoptosis rate when different formulations used. The 2D fluorescent images proved the presence of drug-containing niosomes in the tumor cells. The activation of the apoptotic pathway leading to protein synthesis was confirmed using an ELISA assay, which specifically evaluated the presence of cas3 and cas7. The results of this study indicated the antiproliferative efficacy of optimized niosomal formulations and their mechanism of action. Therefore, niosomes could be utilized as a suitable carrier for delivering sunitinib into lung cancer cells, paving the way for future clinical studies.

Combining Three Tyrosine Kinase Inhibitors: Drug Monitoring Is the Key

A combination of tyrosine kinase inhibitors (TKIs) is likely to be a therapeutic option for numerous oncological situations due to high frequency of oncogenic addiction and progress in precision oncology. Non-small cell lung cancer (NSCLC) represents a subtype of tumors for which oncogenic drivers are frequently involved. To the best of our knowledge, we report the first case of a patient treated with three different TKIs. Osimertinib and crizotinib were administered concurrently for an epidermal growth factor receptor (EGFR)-mutated NSCLC developing a MET amplification as a resistance mechanism to osimertinib. Simultaneously, imatinib was administered for a metastatic gastrointestinal stromal tumor. The progression-free survival was 7 months for both tumors with this tritherapy. The use of therapeutic drug monitoring to assess plasma concentrations of each TKI was a powerful tool to manage the toxicity profile of this combination (creatine phosphokinase elevation) while preserving an optimal exposure to each TKI and treatment efficacy. We observed an imatinib over-exposition related to crizotinib introduction, probably explained by drug–drug interaction mediated by crizotinib enzymatic inhibition on cytochrome P-450 3A4. Posology adjustment due to therapeutic drug monitoring was probably involved in the good survival outcome of the patient. This tool should be used more routinely for patients treated by TKIs to prevent co-treatment interactions and, in particular, for patients receiving TKI combinations to obtain optimal therapeutic exposure and efficacy while reducing possible side-effects.

The Role of Organic Cation Transporters in the Pharmacokinetics, Pharmacodynamics and Drug-Drug Interactions of Tyrosine Kinase Inhibitors

Tyrosine kinase inhibitors (TKIs) decisively contributed in revolutionizing the therapeutic approach to cancer, offering non-invasive, tolerable therapies for a better quality of life. Nonetheless, degree and duration of the response to TKI therapy vary depending on cancer molecular features, the ability of developing resistance to the drug, on pharmacokinetic alterations caused by germline variants and unwanted drug-drug interactions at the level of membrane transporters and metabolizing enzymes. A great deal of approved TKIs are inhibitors of the organic cation transporters (OCTs). A handful are also substrates of them. These transporters are polyspecific and highly expressed in normal epithelia, particularly the intestine, liver and kidney, and are, hence, arguably relevant sites of TKI interactions with other OCT substrates. Moreover, OCTs are often repressed in cancer cells and might contribute to the resistance of cancer cells to TKIs. This article reviews the OCT interactions with approved and in-development TKIs reported in vitro and in vivo and critically discusses the potential clinical ramifications thereof.