Clinical Evaluation of the Effect of Encorafenib on Bupropion, Rosuvastatin, and Coproporphyrin I and Considerations for Statin Coadministration.

BACKGROUND AND OBJECTIVES: Encorafenib is a kinase inhibitor indicated for the treatment of patients with unresectable or metastatic melanoma or metastatic colorectal cancer, respectively, with selected BRAF V600 mutations. A clinical drug-drug interaction (DDI) study was designed to evaluate the effect of encorafenib on rosuvastatin, a sensitive substrate of OATP1B1/3 and breast cancer resistance protein (BCRP), and bupropion, a sensitive CYP2B6 substrate. Coproporphyrin I (CP-I), an endogenous substrate for OATP1B1, was measured in a separate study to deconvolute the mechanism of transporter DDI. METHODS: DDI study participants received a single oral dose of rosuvastatin (10 mg) and bupropion (75 mg) on days - 7, 1, and 14 and continuous doses of encorafenib (450 mg QD) and binimetinib (45 mg BID) starting on day 1. The CP-I data were collected from participants in a phase 3 study who received encorafenib (300 mg QD) and cetuximab (400 mg/m2 initial dose, then 250 mg/m2 QW). Pharmacokinetic and pharmacodynamic analysis was performed using noncompartmental and compartmental methods. RESULTS: Bupropion exposure was not increased, whereas rosuvastatin Cmax and area under the receiver operating characteristic curve (AUC) increased approximately 2.7 and 1.6-fold, respectively, following repeated doses of encorafenib and binimetinib. Increase in CP-I was minimal, suggesting that the primary effect of encorafenib on rosuvastatin is through BCRP. Categorization of statins on the basis of their metabolic and transporter profile suggests pravastatin would have the least potential for interaction when coadministered with encorafenib. CONCLUSION: The results from these clinical studies suggest that encorafenib does not cause clinically relevant CYP2B6 induction or inhibition but is an inhibitor of BCRP and may also inhibit OATP1B1/3 to a lesser extent. Based on these results, it may be necessary to consider switching statins or reducing statin dosage accordingly for coadministration with encorafenib. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov NCT03864042, registered 6 March 2019.

Novel Application of the Two-Period Microtracer Approach to Determine Absolute Oral Bioavailability and Fraction Absorbed of Ertugliflozin.

Ertugliflozin, a sodium glucose cotransporter-2 inhibitor, is approved in the United States for treatment of type 2 diabetes mellitus. A novel two-period study design with 14 C microtracer dosing in each period was used to determine absolute oral bioavailability (F) and fraction absorbed (Fa ) of ertugliflozin. Eight healthy adult men received 100-µg i.v. 14 C-ertugliflozin (400 nCi) dose 1 h after a 15-mg oral unlabeled ertugliflozin dose (period 1), followed by 100 µg 14 C-ertugliflozin orally along with 15 mg oral unlabeled ertugliflozin (period 2). Unlabeled ertugliflozin plasma concentrations were determined using high-performance liquid-chromatography tandem mass spectrometry (HPLC-MS/MS). 14 C-ertugliflozin plasma concentrations were determined using HPLC-accelerator mass spectrometry (AMS) and 14 C urine concentrations were determined using AMS. F ((area under the curve (AUC)p.o. /14 C-AUCi.v. )*(14 C-Dosei.v. /Dosep.o. )) and Fa ((14 C_Total_Urinep.o. /14 C_Total_Urinei.v. )* (14 C-Dosei.v. /14 C-Dosep.o. )) were estimated. Estimates of F and Fa were 105% and 111%, respectively. Oral absorption of ertugliflozin was complete under fasted conditions and F was ∼100%. Ertugliflozin was well tolerated.

Absolute Bioavailability of Bosutinib in Healthy Subjects From an Open-Label, Randomized, 2-Period Crossover Study.

This study evaluated the absolute bioavailability of bosutinib and assessed its safety and tolerability after single-dose oral and intravenous administration. In this phase 1 open-label, 2-sequence, 2-period crossover study, healthy, fed subjects aged 18-55 years were randomized to 1 of 2 treatment sequences (n = 7/sequence): oral bosutinib (100 mg × 5) followed by intravenous bosutinib (120 mg in approximately 240 mL over 1 hour), with a ≥14-day washout, or intravenous bosutinib and then oral bosutinib. Results of plasma pharmacokinetics analyses demonstrated that exposure to intravenous bosutinib was 3-fold higher than for oral bosutinib (16.2 and 5.5 ng·h/mL/mg, respectively), and mean terminal half-life was similar (35.5 and 31.7 hours). The ratio of adjusted geometric means (90%CI) for the dose-normalized area under the plasma concentration-time profile (AUC0-∞ /D) was 33.85% (30.65%-37.38%). Most treatment-emergent adverse events (AEs) were mild in severity. Gastrointestinal (GI) AEs occurred in 9 of 13 subjects given oral bosutinib, whereas no subjects given intravenous bosutinib experienced GI AEs, suggesting bosutinib present in the GI tract had an effect. Bosutinib exhibited an absolute bioavailability of 33.85% based on the ratio of AUC0-∞ /D. Both oral and intravenous bosutinib were safe and well tolerated in healthy, fed adult subjects.

Effect of bosutinib on the absorption of dabigatran etexilate mesylate, a P-glycoprotein substrate, in healthy subjects.

PURPOSE: Bosutinib, a dual Src and Abl tyrosine kinase inhibitor for the treatment of chronic myeloid leukemia, demonstrated concentration-dependent inhibitory effects on P-glycoprotein (P-gp)-mediated digoxin efflux in vitro, suggesting that bosutinib may inhibit P-gp substrates. The effect of bosutinib on dabigatran etexilate mesylate (EM) absorption, a P-gp substrate, was evaluated. METHODS: In this open-label, randomized, single-dose, one-cohort, two-sequence, two-period crossover study, healthy, fed subjects received dabigatran EM (150 mg × 1 orally) alone or 1 h after receiving bosutinib tablets (100 mg × 5 orally). RESULTS: Dabigatran EM monotherapy and concurrent administration of dabigatran EM with bosutinib resulted in similar values for concentration time curves from time zero extrapolated to infinity (AUCinf), but slightly lower maximum plasma concentration (C max) values (AUCinf, 1182 and 1186 ng·h/mL, respectively; C max, 129.8 and 114.1 ng/mL). The time to maximum concentration for dabigatran was 2.99 and 3.99 h for combination therapy. The ratio of the adjusted geometric means (test/reference) of dabigatran AUCinf and C max (90 % confidence interval) were 101.4 % (89.6-114.9 %) and 89.7 % (77.8-103.4 %), respectively, following administration of dabigatran EM with bosutinib (test) relative to dabigatran EM administered alone (reference). Six subjects receiving combination treatment reported a total of seven adverse events (AEs) versus none for subjects receiving monotherapy alone. All AEs were mild to moderate and considered treatment related. CONCLUSION: These data demonstrate that single doses of bosutinib do not affect dabigatran exposure, suggesting that bosutinib is not a clinical inhibitor of P-gp. TRIAL REGISTRATION: ClinicalTrials.gov NCT02102633. https://clinicaltrials.gov/ct2/show/NCT02102633?term=NCT02102633&rank=1.

Effect of aprepitant, a moderate CYP3A4 inhibitor, on bosutinib exposure in healthy subjects.

PURPOSE: Bosutinib is an oral, dual Src and Abl tyrosine kinase inhibitor (TKI) approved for the treatment of Philadelphia chromosome-positive chronic myeloid leukemia resistant or intolerant to prior TKI therapy. Bosutinib is primarily metabolized by cytochrome P450 (CYP) 3A4, suggesting drug interaction potential with other CYP3A4 modulators. This open-label, randomized, 2-sequence, 2-period crossover study assessed the effect of single-dose aprepitant, a moderate CYP3A4 inhibitor, on the single-dose pharmacokinetic profile of oral bosutinib 500 mg. METHODS: Nineteen healthy, fed adults received bosutinib (100 mg × 5) alone or coadministered with aprepitant (125 mg × 1) in each treatment period (with a ≥14-day washout); serial blood samples were analyzed. Safety was evaluated. RESULTS: Following coadministration of aprepitant with bosutinib, the area under the concentration-time curve from time zero extrapolated to infinity (AUCinf) and maximum plasma concentration (C max) were higher than in bosutinib alone (AUCinf, 4719 and 2268 ng•h/mL; C max, 146.0 and 94.94 ng/mL). For bosutinib with aprepitant versus bosutinib alone, mean terminal elimination half-life was similar (25.99 vs 27.79 h), time to C max was longer (6.02 vs 4.15 h), and apparent oral clearance (CL/F) was decreased (105.9 vs 220.4 L/h). The ratio of adjusted geometric means of AUCinf and C max for bosutinib with aprepitant relative to bosutinib alone were 199 % (90 % confidence interval, 167-237 %) and 153 % (127-184 %), respectively. Both treatments were well tolerated. CONCLUSION: In healthy volunteers, administering a single dose of aprepitant increased the AUC and C max following a single dose of bosutinib by 99 and 53 %, respectively. These results are consistent with a moderate CYP3A4 inhibitor effect of aprepitant on bosutinib (Trial Registration: ClinicalTrials.gov NCT02058277).

Repeat-dose sirolimus pharmacokinetics and pharmacodynamics in patients with hepatic allografts.

PURPOSE: To determine sirolimus steady-state pharmacokinetics, and to assess the relationship between time-normalized trough sirolimus concentration (C(min,TN)) and evidence of efficacy (rejection and death) and adverse reactions (stomatitis and pneumonia) in liver allograft patients. METHODS: Dense sampling of sirolimus was performed over a single daily-dosing interval in 11 hepatic allograft recipients on day 28 and at 3 months after start of treatment. Serial trough concentration sampling was performed in 380 hepatic allograft recipients on days 1, 7, 14, 28, 42, 60, 90, 180, 270 and 360 after start of treatment. Occurrence of stomatitis, pneumonia, rejection, and death were collected for 360 days after start of treatment. Noncompartmental pharmacokinetic parameters were analyzed in the 11 densely sampled patients; C(min,TN) was determined in the 380 patients. RESULTS: Mean maximum concentration (C(max)), time to C(max) (t(max)), area under the curve for the given dose interval (AUC(tau)), and whole blood oral clearance at 3 months were 20.8 ± 7.6 ng/mL, 3 ± 1 h, 338 ± 144 ng·h/mL, and 10.0 ± 5.6 L/hr, respectively. In the 11 densely sampled patients, linear regression showed that C(min,TN) was highly predictive of AUC(tau) (r² = 0.77, P < 0.0001) at each analysis time point. Logistic regression showed a relationship between C(min,TN) in the 380 patients and pneumonia occurrence, but not between C(min,TN) and stomatitis, rejection, or death. CONCLUSIONS: In this study, the pharmacokinetic profile of sirolimus in hepatic allograft patients was consistent with that of renal transplantation recipients. With the exception of pneumonia, no correlation was observed between C(min,TN) and the occurrence of adverse events of interest.