Effect of the Histone Deacetylase Inhibitor FRM-0334 on Progranulin Levels in Patients With Progranulin Gene Haploinsufficiency: A Randomized Clinical Trial

Key Points Question What is the safety, tolerability, pharmacodynamic, and pharmacokinetic profile of the histone deacetylase inhibitor FRM-0334 in participants with progranulin gene (GRN) haploinsufficiency? Findings In this randomized placebo-controlled clinical trial including 27 participants with GRN haploinsufficiency, FRM-0334 was safe and well tolerated; however, it failed to increase plasma progranulin and cerebrospinal fluid progranulin and failed to demonstrate dose-dependent oral bioavailability. Meaning The studied formulation of FRM-0334 should not be investigated in future clinical trials enrolling participants with GRN haploinsufficiency; this study did not fully address the potential of histone deacetylase inhibition to alter GRN expression.
This randomized clinical trial investigates the pharmacokinetic and pharmacodynamic profile, tolerability, and safety of the histone deacetylase inhibitor FRM-0334 in people with progranulin gene haploinsufficiency.
Importance Histone deacetylase inhibitors have been repeatedly shown to elevate progranulin levels in preclinical models. This report describes the first randomized clinical trial of a histone deacetylase inhibitor in frontotemporal dementia (FTD) resulting from progranulin (GRN) gene variations. Objective To characterize the safety, tolerability, plasma pharmacokinetics, and pharmacodynamic effects of oral FRM-0334 on plasma progranulin and other exploratory biomarkers, including fluorodeoxyglucose (FDG)–positron emission tomography (PET), in individuals with GRN haploinsufficiency. Design, Setting, and Participants In this randomized, double-blind, placebo-controlled, dose-escalating, phase 2a safety, tolerability, and pharmacodynamic clinical study, 2 doses of a histone deacetylase inhibitor (FRM-0334) were administered to participants with prodromal to moderate FTD with granulin variations. Participants were recruited from January 13, 2015, to April 13, 2016. The study included 27 participants with prodromal (n = 8) or mild-to-moderate symptoms of FTD (n = 19) and heterozygous pathogenic variations in GRN and was conducted at multiple centers in North America, the UK, and the European Union. Data were analyzed from June 9, 2019, to May 13, 2021. Interventions Daily oral placebo (n = 5), 300 mg of FRM-0334 (n = 11), or 500 mg of FRM-0334 (n = 11) was administered for 28 days. Main Outcomes and Measures Primary outcomes were safety and tolerability of FRM-0334 and its peripheral pharmacodynamic effect on plasma progranulin. Secondary outcomes were the plasma pharmacokinetic profile of FRM-0334 and its pharmacodynamic effect on cerebrospinal fluid progranulin. Exploratory outcomes were FDG-PET, FTD clinical severity, and cerebrospinal fluid biomarkers (neurofilament light chain [NfL], amyloid β 1-42, phosphorylated tau 181, and total tau [t-tau]). Results A total of 27 participants (mean [SD] age, 56.6 [10.5] years; 16 women [59.3%]; 26 White participants [96.3%]) with GRN variations were randomized and completed treatment. FRM-0334 was safe and well tolerated but did not affect plasma progranulin (4.3 pg/mL per day change after treatment; 95% CI, –10.1 to 18.8 pg/mL; P = .56), cerebrospinal fluid progranulin (0.42 pg/mL per day; 95% CI, –0.12 to 0.95 pg/mL; P = .13), or exploratory pharmacodynamic measures. Plasma FRM-0334 exposure did not increase proportionally with dose. Brain FDG-PET data were available in 26 of 27 randomized participants. In a cross-sectional analysis of 26 individuals, bifrontal cortical FDG hypometabolism was associated with worse Clinical Dementia Rating (CDR) plus National Alzheimer’s Coordinating Center frontotemporal lobar degeneration sum of boxes score (b = −3.6 × 10−2 standardized uptake value ratio [SUVR] units/CDR units; 95% CI, −4.9 × 10−2 to −2.2 × 10−2; P