Concentration-QTcF Modeling of Icenticaftor from a Randomized, Placebo- and Positive-Controlled Thorough QT Study in Healthy Participants.

Icenticaftor (QBW251) is a potentiator of the cystic fibrosis transmembrane receptor. Based on its mechanism of action, icenticaftor is expected to provide benefits in patients with chronic obstructive pulmonary disease by restoring mucociliary clearance, which would eventually lead to a reduction of bacterial colonization and related inflammatory cascade. A placebo- and positive-controlled, 4-way crossover thorough QT study was conducted in 46 healthy participants with the objective to assess the effect of therapeutic (300 mg twice daily for 6 days) and supratherapeutic (750 mg twice daily for 6 days) oral doses of icenticaftor on electrocardiogram parameters, including concentration-corrected QT (QTc) analysis. Moxifloxacin (400 mg, oral) was used as a positive control. In the concentration-QTc analysis performed on pooled data from Day 1 and Day 6 (steady state), the estimated population slope was shallow and slightly negative: -0.0012 ms/ng/mL. The effect on the Fridericia corrected QT (QTcF) interval (∆ΔQTcF) was predicted to be -1.3 milliseconds at the icenticaftor 300-mg twice-daily peak concentration (geometric mean was 1094 ng/mL) and -5.5 milliseconds at the 750-mg twice-daily peak concentration (geometric mean Cmax was 4529 ng/mL) indicated a mild shortening effect of icenticaftor on QTcF interval length. The results of the by-time-point analysis indicated least squares placebo corrected mean ∆∆QTcF across time points ranged from -7.9 to 0.1 milliseconds at 1 and 24 hours after dosing both on Day 6 in the 750-mg dose group compared with -3.7 to 1.6 milliseconds at 1.5 and 24 hours after dosing on Day 1 in the 300-mg dose group. Assay sensitivity was demonstrated with moxifloxacin. The large accumulation of exposures, especially the 4.3-fold increase in peak plasma concentration observed at the icenticaftor 750-mg twice-daily dosage compared with Icenticaftor 300 mg twice daily (2.3-fold) on Day 6 provided a large concentration range (up to 9540 ng/mL) to evaluate the effect of icenticaftor on ΔΔQTcF. Based on the concentration-QTc analysis, an effect on ΔΔQTcF exceeding 10 milliseconds can be excluded within the full observed ranges of plasma concentrations on icenticaftor, up to approximately 9540 ng/mL. Icenticaftor at the studied doses demonstrated a mild shortening in QTcF, which is unlikely to be of clinical relevance in a therapeutic setting.

Novel Bruton's tyrosine kinase inhibitor remibrutinib: Assessment of drug-drug interaction potential as a perpetrator of cytochrome P450 enzymes and drug transporters and the impact of covalent binding on possible drug interactions.

PURPOSE: Pharmacokinetic drug-drug interactions (DDIs) are investigated to ensure safety for patients receiving concomitant medications. Here, we present a strategy to characterise the DDI potential of remibrutinib, as an inhibitor of drug-metabolising enzymes and drug transporters, and as an inducer. Initial in vitro studies were performed, followed by a biomarker-based assessment of induction in a first in human study, concluded by a clinical study to verify initial results. Remibrutinib is a covalent inhibitor of Bruton's Tyrosine kinase (BTKi) carrying a reactive acrylamide moiety (warhead), thus the potential contribution of covalent binding (off-target) to observed interactions was investigated as this could lead to prolonged and more potent drug interactions. METHODS: DDI assessment was focused on the putative inhibition of key metabolic enzymes (Cytochrome P450, CYP), drug transporters and a potential effect on oral contraceptives (OC) by induction of enzymes that are involved in their clearance (CYP3A4). The impact of covalent binding was assessed by synthesising an identical reference molecule but with an inactivated warhead. RESULTS: An interaction potential of limited clinical relevance was revealed for remibrutinib for CYP enzymes and drug transporters. The reactive warhead of remibrutinib had no impact on CYP enzyme and transporter inhibition, including time-dependent inhibition of CYP3A4, but may increase the induction potential of remibrutinib. CONCLUSIONS: Observed inhibition of metabolic enzymes indicated that remibrutinib is a weak inhibitor of CYP3A4 and CYP2C9 and is not a clinically relevant inhibitor of uptake and efflux transporters, except for intestinal P-glycoprotein and breast cancer resistance protein inhibition. OC may be safely administered and are effective when given with pharmacologically relevant doses of remibrutinib.

Novel Bruton's Tyrosine Kinase inhibitor remibrutinib: Drug-drug interaction potential as a victim of CYP3A4 inhibitors based on clinical data and PBPK modeling.

Remibrutinib, a novel oral Bruton's Tyrosine Kinase inhibitor (BTKi) is highly selective for BTK, potentially mitigating the side effects of other BTKis. Enzyme phenotyping identified CYP3A4 to be the predominant elimination pathway of remibrutinib. The impact of concomitant treatment with CYP3A4 inhibitors, grapefruit juice and ritonavir (RTV), was investigated in this study in combination with an intravenous microtracer approach. Pharmacokinetic (PK) parameters, including the fraction absorbed, the fractions escaping intestinal and hepatic first-pass metabolism, the absolute bioavailability, systemic clearance, volume of distribution at steady-state, and the fraction metabolized via CYP3A4 were evaluated. Oral remibrutinib exposure increased in the presence of RTV 4.27-fold, suggesting that remibrutinib is not a sensitive CYP3A4 substrate. The rich PK dataset supported the building of a robust physiologically-based pharmacokinetic (PBPK) model, which well-described the therapeutic dose range of 25-100 mg. Simulations of untested scenarios revealed an absence of drug-drug interaction (DDI) risk between remibrutinib and the weak CYP3A4 inhibitor fluvoxamine (area under the concentration-time curve ratio [AUCR] <1.25), and a moderate effect with the CYP3A4 inhibitor erythromycin (AUCR: 2.71). Predictions with the moderate and strong CYP3A4 inducers efavirenz and rifampicin, suggested a distinct remibrutinib exposure decrease of 64% and 89%. Oral bioavailability of remibrutinib was 34%. The inclusion of an intravenous microtracer allowed the determination of all relevant remibrutinib PK parameters, which facilitated construction of the PBPK model. This will provide guidance on the selection or restriction of comedications and prediction of DDI risks.