Purpose: This phase I trial was undertaken to determine the maximum tolerated dose (MTD), doselimiting toxicities (DLT), safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity of the novel smoothened inhibitor sonidegib (LDE225), a potent inhibitor of hedgehog signaling, in patients with advanced solid tumors.Experimental Design: Oral sonidegib was administered to 103 patients with advanced solid tumors, including medulloblastoma and basal cell carcinoma (BCC), at doses ranging from 100 to 3,000 mg daily and 250 to 750 mg twice daily, continuously, with a single-dose pharmacokinetics run-in period. Dose escalations were guided by a Bayesian logistic regression model. Safety, tolerability, efficacy, pharmacokinetics, and biomarkers in skin and tumor biopsies were assessed.Results: The MTDs of sonidegib were 800 mg daily and 250 mg twice daily. The main DLT of reversible grade 3/4 elevated serum creatine kinase (18% of patients) was observed at doses ! the MTD in an exposuredependent manner. Common grade 1/2 adverse events included muscle spasm, myalgia, gastrointestinal toxicities, increased liver enzymes, fatigue, dysgeusia, and alopecia. Sonidegib exposure increased dose proportionally up to 400 mg daily, and displayed nonlinear pharmacokinetics at higher doses. Sonidegib exhibited exposure-dependent reduction in GLI1 mRNA expression. Tumor responses observed in patients with medulloblastoma and BCC were associated with evidence of hedgehog pathway activation.Conclusions: Sonidegib has an acceptable safety profile in patients with advanced solid tumors and exhibits antitumor activity in advanced BCC and relapsed medulloblastoma, both of which are strongly associated with activated hedgehog pathway, as determined by gene expression.

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The long-term dental safety profile of high-dose radioiodine therapy remained elusive despite more than 6 decades of clinical use. Methods: In a cohort study, we investigated the incidence of sialadenitis, xerostomia, caries, and tooth extractions after high-dose radioiodine therapy for differentiated thyroid cancer and explored risk factors by multiple regression models. Results: One hundred seventy-six participants were recruited (median follow-up, 6.6 y; range, 1.1-32.6 y; patient-years: 8,472 before and 1,421 after radioiodine therapy). Scintigraphic salivary gland uptake during radioiodine treatment predicted development of sialadenitis (odds ratio: 1.31 [1.05-1.63], P 5 0.015) and xerostomia (odds ratio: 1.58 [1.16-2.16], P 5 0.004). The caries risk increased by postradioiodine xerostomia (% increase: 98.8 [26.5-212], P 5 0.003). The long-term risk for postradioiodine tooth extractions increased with increasing cumulative radioiodine activities (% increase [per gigabequerel]: 8.14 [1.07, 15.7], P 5 0.02). Conclusion: High-dose radioiodine treatment can impair the long-term dental health, depending on the cumulative radioiodine activity and individual salivary gland radioiodine uptake.

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