PURPOSE: Recent data indicate that there is a significant cross-talk between the PI3K/Akt/mTOR and androgen receptor signaling pathways.
We evaluated safety and tolerability as well as potential drug-drug interaction of ridaforolimus, a mammalian target of rapamycin (mTOR) inhibitor, when combined with the androgen receptor inhibitor bicalutamide in patients with asymptomatic, metastatic castration-resistant prostate cancer.
PATIENTS AND METHODS: Patients were treated with the combination of ridaforolimus 30 mg/day for 5 consecutive days each week and bicalutamide 50 mg/day. Ridaforolimus pharmacokinetics was assessed with and without bicalutamide.
RESULTS: Twelve patients were enrolled including 1 screen failure. Dose reductions were required in 7 patients. Three of the 11 patients experienced a dose-limited toxicity, 1 with Grade 3 hyperglycemia and 2 with Grade 2 stomatitis leading to < 75 % of planned ridaforolimus dose during the first 35 days of study treatment. The pharmacokinetic results showed no differences in exposures to ridaforolimus with and without concomitant bicalutamide administration.
CONCLUSIONS: Although there was no evidence of a clinically relevant pharmacological drug-drug interaction, the occurrence of dose-limiting toxicities in 3 of 11 evaluable patients at a reduced dose of ridaforolimus of 30 mg/day suggests that this combination may not be well suited for asymptomatic or minimally symptomatic prostate cancer patients.
Written by:
Meulenbeld HJ, de Bono JS, Tagawa ST, Whang YE, Li X, Heath KH, Zandvliet AS, Ebbinghaus SW, Hudes GR, de Wit R. Are you the author?
Department of Medical Oncology, Erasmus University Medical Center, Daniel den Hoed Cancer Center, Groene Hilledijk 301, 3008 AE, Rotterdam, The Netherlands.
Reference: Cancer Chemother Pharmacol. 2013 Aug 7. Epub ahead of print.
doi: 10.1007/s00280-013-2250-6
PubMed Abstract
PMID: 23921574
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