A Phase I Study of the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of the Novel Dopamine D1 Receptor Partial Agonist, PF-06669571, in Subjects with Idiopathic Parkinson's Disease.

BACKGROUND AND OBJECTIVES

There is an unmet medical need for additional treatment options for Parkinson's disease. This was a Phase I, double-blind clinical trial assessing safety, tolerability, pharmacokinetics, and pharmacodynamics of multiple doses of the novel dopamine D1 receptor partial agonist, PF-06669571, in subjects with idiopathic Parkinson's disease on a stable dose of L-DOPA.

METHODS

Subjects received PF-06669571 (or matching placebo) titrated from 1 mg to 3 mg over 7 days. The primary pharmacodynamic endpoint was the change from baseline in Movement Disorder Society-Unified Parkinson's Disease Rating Scale Part III total motor score at the pharmacodynamic time of maximum change from baseline on day 7.

RESULTS

Twenty subjects were randomized and 19 completed the study. Maximum plasma concentrations (C) of PF-06669571 were reached 3.35 and 3.19 h post-dose on day 1 and day 7. Geometric mean C and area under the plasma concentration-time profile from time 0 to 24 h post-dose on day 7 were 92.51 ng/mL and 1626 ng·h/mL, respectively. The primary pharmacodynamic endpoint did not meet the pre-specified criteria for significant improvement; however, the criteria were met in a sensitivity analysis excluding data from a L-DOPA outlier (L-DOPA dose of 2550 mg/d). The most common adverse events (AEs) were nausea (experienced by 2 subjects each in the PF-06669571 and placebo groups). There were no permanent discontinuations or dose reductions due to AEs.

DISCUSSION

Multiple daily doses of PF-06669571 were safe and well tolerated with no notable safety concerns. The pharmacodynamic endpoint did not meet the pre-specified criteria for significant improvement. CLINICALTRIALS.

GOV IDENTIFIER

NCT02565628.