Comparison of the Pharmacokinetics of the Phase II and Phase III Capsule Formulations of Selumetinib and the Effects of Food on Exposure: Results From Two Randomized Crossover Trials in Healthy Male Subjects.

PURPOSE

Selumetinib (AZD6244, ARRY-142886), an oral, potent, and highly selective mitogen-activated protein kinase 1/2 inhibitor with a short half-life, has shown activity across various tumor types. Before initiation of Phase III trials, the site, scale, and color (hypromellose shell from white [Phase II] to blue [Phase III]) of the selumetinib 25mg capsule manufacture was changed. We present 2 crossover trials evaluating Phase III capsules in healthy subjects.

METHODS

The relative bioavailability trial was a Phase I, open-label, randomized, 3-treatment, 4-period, 6-sequence crossover trial in healthy male subjects (aged 18-55 years). Subjects received selumetinib 75mg (3 × 25 mg) Phase II or Phase III capsules, or a 35mg oral solution, during 4 dosing periods in 1 of 6 randomized treatment sequences. The food effect trial was a Phase I, open-label, randomized, 2-period crossover trial in healthy male subjects (aged 18-45 years). Subjects were randomized to 1 of 2 sequences to receive selumetinib 75mg (3 × 25 mg) Phase III capsules. In sequence 1, subjects received selumetinib after 10 hours of fasting. Following a washout period, selumetinib was administered after a high-fat meal. In sequence 2, subjects received selumetinib in the fed state, before the fasted state. Pharmacokinetic parameters were determined from serial blood sampling.

FINDINGS

Twenty-seven subjects were randomized to the relative bioavailability trial; 26 completed all dosing periods. Mean selumetinib AUC was unchanged (geometric least squares mean ratio [GLSMR], 90.01% [90% CI, 81.74-99.11]). C was 18% lower with the Phase III capsules (GLSMR, 81.97% [90% CI, 69.01-97.36]). A post hoc exploratory statistical analysis excluding outlying observations with later T showed that Phase II and III capsules produced similar exposure in terms of C and AUC. High intrasubject variability for C attributed to the pharmacokinetic sampling schedule was judged to have impacted on the estimated GLSMR. In the food effect trial, 34 subjects completed both study periods. A high-fat meal reduced selumetinib C compared with the fasted state (GLSMR, 49.76% [90% CI, 43.82-56.51]); AUC was minimally changed (GLSMR, 84.08% [90% CI, 80.72-87.59]). Median T was prolonged by 1.49 hours. No deaths or serious adverse events were reported.

IMPLICATIONS

Selumetinib 75mg (3 × 25 mg) Phase III capsules are being used in ongoing pivotal Phase III trials and should be administered in the fasted state. Based on findings from the relative bioavailability trial, pharmacokinetic sampling frequency was increased for healthy subject trials, including the food effect trial. ClinicalTrials.gov identifiers: NCT01635023 (relative bioavailability) and NCT01974349 (food effect).