Background: In phase I testing in 22 patients with neuroblastoma, the maximum tolerated dose of alisertib tablets with irinotecan/temozolomide was 60 mg/m2/dose. This combination showed significant activity [31.8% response rate; 52.4% 2-year PFS]. This study sought to: confirm the activity of this regimen; evaluate an alisertib oral solution (OS); and identify predictors of response and toxicity.
Methods: We conducted a two-stage phase II trial of alisertib tablets (60 mg/m2/dose x 7 days), irinotecan (50 mg/m2/dose IV x 5 days), and temozolomide (100 mg/m2/dose orally x 5 days) in patients 1-30 years of age with relapsed/refractory neuroblastoma. The primary endpoint was best response. Secondary endpoints were toxicity, PFS, and pharmacokinetics. A cohort was treated with alisertib OS at 45 mg/m2, a dose anticipated to be bioequivalent to 60 mg/m2 tablets. Exploratory analyses evaluated predictors of response and toxicity using data from phase I, II, and OS cohorts.
Results: Twenty and 12 patients were treated in phase II and OS cohorts, respectively. Hematologic toxicities were the most common adverse events. In phase II, 4 responses (20%) were observed as well as 4 patients with minor responses. The 1-year PFS was 64.5%. In the OS cohort, 3 patients (25%) had first course dose-limiting toxicity (DLT). Two of 12 patients had objective responses (16.6%) and 1 had a minor response. The alisertib OS at 45 mg/m2 had higher median Cmax (8.7 vs. 3.9 mM) and exposure (58 vs. 45 mM·hr) compared to tablets at 60 mg/m2. Across 54 patients in all cohorts, there were trends to suggest that MYCN amplification and prior irinotecan treatment were associated with lower response rates. Alisertib exposure and trough concentrations were associated with higher rates of first course DLT.
Conclusions: Alisertib with irinotecan/temozolomide is an active combination. Alisertib oral solution at 45 mg/m2 is tolerable in this context. Additional studies of biomarkers of response and toxicity are ongoing.