Phase I, multicenter, open‐label, dose‐escalation study of sonidegib in Asian patients with advanced solid tumors

Sonidegib is a selective inhibitor of Smoothened receptor, which is a key regulator of the Hedgehog signaling pathway. The purpose of this study was to determine the maximum tolerated dose based on dose‐limiting toxicity (DLT) and the recommended dose (RD) of sonidegib in Asian patients with advanced solid tumors. This was an open‐label, single‐arm, multicenter, two‐group, parallel, dose‐escalation, phase I study undertaken in Asian patients; group 1 included patients from Japan and group 2 included patients from Hong Kong and Taiwan. Dose escalation was guided by a Bayesian logistic regression model dependent on DLTs in cycle 1 and other safety findings. A total of 45 adult Asian patients with confirmed advanced solid tumors were enrolled. Group 1 included 21 patients (12 treated with 400 mg q.d. [once daily] and 9 treated with 600 mg q.d.) and group 2 included 24 patients (12 treated with 400 mg q.d., 8 treated with 600 mg q.d., and 4 treated with 800 mg q.d.). Elevation in creatine kinase was the DLT in both groups. The most common adverse events suspected to be related to sonidegib in both patient groups were increase in creatine kinase levels, myalgia, fatigue, and abnormal hepatic function. The RD of 400 mg q.d. was defined in both groups. Difference in tolerability was noted between the East Asian patients and Western population. The RD in East Asian patients (400 mg q.d.) was lower than in patients from Europe and the USA (800 mg q.d. and 250 mg twice daily). (Registered with Clinicaltrials.gov: NCT01208831.)