Mass Balance, Routes of Excretion, and Pharmacokinetics of Investigational Oral [C]-alisertib (MLN8237), an Aurora A Kinase Inhibitor in Patients with Advanced Solid Tumors

Aims This two-part, phase I study evaluated the mass balance, excretion, pharmacokinetics and safety of the investigational aurora A kinase inhibitor, alisertib, in three patients with advanced malignancies. Methods Part A; patients received a single 35-mg dose of [C]-alisertib oral solution (~80 μCi total radioactivity [TRA]). Serial blood, urine, and fecal samples were collected up to 336 h post-dose for alisertib mass balance and pharmacokinetics in plasma and urine by liquid chromatography-tandem mass spectrometry, and mass balance/recovery of [C]-radioactivity in urine and feces by liquid scintillation counting. Part B; patients received non-radiolabeled alisertib 50 mg as enteric-coated tablets twice-daily for 7 days in 21-day cycles. Results In part A, absorption was fast (median plasma T, 1 h) for alisertib and TRA. Mean plasma t for alisertib and TRA were 23.4 and 42.0 h, respectively. Mean plasma alisertib/TRA AUC ratio was 0.45, indicating presence of alisertib metabolites in circulation. Mean TRA blood/plasma AUC ratio was 0.60, indicating preferential distribution of drug-related material in plasma. On average, 87.8% and 2.7% of administered radioactivity was recovered in feces and urine, respectively (total recovery, 90.5% by 14 days post-dose). In part B, patients received a median 3 cycles of alisertib. The most common any-grade adverse events were fatigue and alopecia. Conclusions Findings suggest that alisertib is eliminated mainly via feces, consistent with hepatic metabolism and biliary excretion of drug-related material. Further investigation of alisertib pharmacokinetics in patients with moderate-severe hepatic impairment is warranted to inform dosing recommendations in these patient populations.