GRN) haploinsufficiency?What is the safety, tolerability, pharmacodynamic, and pharmacokinetic profile of the histone deacetylase inhibitor FRM-0334 in participants with progranulin gene  gene variations.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 –positron emission tomography (PET), in individuals with 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.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 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.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 .GRN variations were randomized and completed treatment. FRM-0334 was safe and well tolerated but did not affect plasma progranulin , cerebrospinal fluid progranulin , 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 , high cerebrospinal fluid NfL , and high CSF t-tau .A total of 27 participants  with GRN haploinsufficiency. International multicenter clinical trials of FTD-GRN are feasible.In this randomized clinical trial, the current formulation of FRM-0334 did not elevate PRGN levels, which could reflect a lack of efficacy at attained exposures, low bioavailability, or some combination of the 2 factors. Bifrontal FDG-PET is a sensitive measure of symptomatic NCT02149160ClinicalTrials.gov Identifier:  GRN (OMIM 138945)6 are among the most common causes of genetic frontotemporal degeneration (FTD).7 Pathogenic GRN variations result in haploinsufficiency,10 with a variable, roughly 50% reduction in secreted PGRN protein in the plasma12 and cerebrospinal fluid (CSF).11 The potential to restore or replace PGRN has spurred the development of a number of new GRN therapies that are entering human clinical trials, with 1 agent having recently entered a phase 3 trial.13 Clinical development programs have been aided by the ability to use blood and CSF PGRN concentrations as pharmacodynamics biomarkers in GRN haploinsufficiency clinical trials. However, the rarity of trial-ready participants and lack of established end points are barriers to successful development of new therapies.Autosomal dominant variations in the progranulin (PGRN) gene 14 In preclinical studies, a similar HDAC inhibitor, suberoylanilide hydroxamic acid, enhanced PGRN transcription to near-normal levels in human-derived GRN-/+(R493X) cells (−/+ denotes that the cells have heterozygous loss of function of the GRN gene) and prevented cytosolic TAR DNA-binding protein 43 accumulation in PGRN-deficient lymphoblasts.16 Although suberoylanilide hydroxamic acid is approved for treatment of cutaneous lymphoma,17 its poor central nervous system availability18 prioritized the exploration of FRM-0334 in GRN haploinsufficiency. In subsequent unpublished preclinical studies, FRM-0334 boosted GRN mRNA and PGRN in a dose-dependent manner in human -/+GRN lymphoblasts and in the cortex of mice . Additionally, single and multiple doses for FRM-0334, ranging from 10 mg to 400 mg daily, were safe, well tolerated, and associated with dose-proportional plasma exposure in an unpublished, phase 1, placebo-controlled clinical trial of FRM-0334 in 87 healthy volunteers aged 18 to 65 years. We investigated the safety, tolerability, and plasma pharmacodynamic (PD) effects (change in PGRN) of FRM-0334 in a multinational clinical trial completed in PRGN GRN haploinsufficiency. We also characterized the peripheral pharmacokinetic (PK) profile and central PD effects (change in CSF PGRN) of FRM-0334 in GRN haploinsufficiency. Additionally, this trial’s inclusion of a variety of exploratory PD end points allowed for novel analyses comparing cortical fluorodeoxyglucose positron emission tomography (FDG-PET), clinical measures of functional FTD severity, and candidate CSF biomarkers of neuronal injury, including neurofilament light chain (NfL), amyloid β 1-42 (Aβ1-42), phosphorylated tau 181 (p-tau181), and total tau (t-tau). We present data from the first trial implementing an international, multisite protocol as a mechanism for patient recruitment in the rare familial FTD space.The histone deacetylase (HDAC) inhibitor FRM-0334, formerly EVP-0334, was designed as a potent, orally available drug with brain-to-plasma concentration ratios of 3 to 6 in rodents.GRN variations, including prodromal and mild-to-moderate 20 FTD stages. Race and ethnicity information was recorded; participants self-identified their race and ethnicity. All participants were recruited and randomized from January 13, 2015, to April 13, 2016, at 11 clinical sites in the US, UK, France, Italy, the Netherlands, and Belgium  was also exclusionary, though these criteria were not cited as the basis for exclusion of any participants recruited for screening  reporting guideline, and local regulations.This randomized clinical trial included participants aged 27 to 75 years with Clinical Laboratory Improvement Amendments–confirmed pathogenic 21 generated randomization assignments in 2 sequential cohorts. Cohort 1 was randomized to placebo or low-dose (300 mg daily) FRM-0334. Cohort 2 began after review of cohort 1 safety data and included randomization to placebo or high-dose (500 mg daily) FRM-0334. Overall, 5 patients were randomized to placebo, 11 to low-dose FRM-0334, and 11 to high-dose FRM-0334. The study drug  and placebo  were presented as identical, opaque, white gelatin capsules and taken daily for 28 days. A central pharmacy was used to distribute packaged drugs to blinded site staff. Plasma collection occurred at screening visit 1 (8-30 days before the first dose), at screening visit 2 (1-7 days before the first dose), on study day 1 (first day of dose), in weekly intervals during dosing , and at 10 days after the final dose (day 38). Lumbar punctures for CSF collection were performed using standard clinical practice, aligned with Alzheimer’s Disease Neuroimaging Initiative procedures,22 on screening day 2 and study day 28 . Cerebrospinal fluid was collected in the afternoon using a gravity drip into a polypropylene collection tube. Magnetic resonance imaging was performed on screening day 1 for safety and diagnostic purposes using scanners, field strengths, and protocols employed for clinical use at each site  and secondary outcome of change in CSF PGRN (screening day 2 and study day 28) were measured via enzyme-linked immunoassay. The cosecondary outcome of FRM-0334 plasma PK properties  were assessed via liquid chromatography and tandem mass spectrometry using day 1  and day 7  plasma. Exploratory CSF biomarkers  and clinical measures  were assessed at screening and on study day 28. Biomarker assay procedures are detailed in the eMethods in The primary outcome of safety and tolerability was assessed via treatment-emergent adverse events (AEs), serum chemistry, hematology, urinalysis, vital signs (including orthostatic measurements), 12-lead electrocardiogram, physical examination, and suicidality assessments.t test, 2-tailed). Longitudinal changes in plasma PGRN, CSF biomarkers, clinical severity, and bifrontal FDG-PET standardized uptake value ratio (FDG-SUVR) were modeled with linear mixed-effects models (controlling for age and sex), allowing each patient’s outcome measures a random slope and intercept with time. In follow-up sensitivity analyses, we modeled interactions between FRM-0334  and time in determining patient outcome measures. The plasma FRM-0334 standard AUC from 0 to the maximum observed time was calculated using cubic splines.26 Linear regression models were used to assess for baseline relationships between baseline PK values and age, sex, FTLD clinical severity , and follow-up PK values (day 1 vs day 7). Linear regression models (controlling for age and sex) were used to investigate baseline cross-sectional linear relationships between bifrontal FDG-SUVR, plasma PGRN, CSF biomarker concentrations, and clinical severity outcome measures. Linear regression models (controlling for age and sex) were also used to investigate linear relationships between magnitude of change in PGRN (plasma or CSF) and magnitude of change in FDG-SUVR, CSF biomarker concentrations, and clinical severity measures after treatment with FRM-0334. Univariate regression models were also used to compare baseline PK values by age and sex. The Shapiro-Wilks W test was used to confirm assumptions of normality , and the Cameron and Trivedi decomposition of IM-test was used to confirm assumptions of residual homoscedasticity. Non-normally distributed dependent variables were log converted before inclusion in our models. Data were analyzed from June 9, 2019, to May 13, 2021.All statistical analyses were performed in STATA, version 14.2 (StataCorp LLC). A description of the original trial protocol statistical analysis plan may be found in the eMethods in P < .001 uncorrected for multiple comparisons, cluster-level familywise error [FWE]–corrected P < .05), converted to Pearson correlation coefficient r maps using the Computational Anatomy Toolbox, version 12 , and rendered on a 3-dimensional brain surface using BrainNet Viewer.27 A more stringent primary threshold of P < .05 FWE-corrected for multiple comparisons was also used for supplemental sensitivity analyses. Based on our initial voxelwise results  we further investigated potential linear relationships between FDG metabolism in a bifrontal region of interest (ROI) and clinical measures or fluid biomarkers. Baseline bifrontal macro ROI FDG-SUVR values were calculated from weighted averages of constituent bilateral frontal SPM12 using ROI definitions from the Neuromorphometrics Atlas28 and compared (as the dependent variable) with clinical measures and fluid biomarkers using linear regression models controlling for age and sex. The included ROIs were anterior, lateral, medial, and posterior orbital gyri, middle and superior frontal gyri, orbital and triangular part of the inferior frontal gyri, and the frontal pole. Change in bifrontal FDG-SUVR over time was also assessed via linear mixed-effects models as a follow-up sensitivity analysis, though the heterogeneity of PET sites and short duration of follow-up limited the potential interpretability of these analyses. The methods of FDG-PET collection and processing (including estimation of W-maps) are further detailed in the eMethods in Baseline FDG-PET data were only available for 26 of 27 individuals randomized to the study drug. Baseline FDG-PET data for the remaining participant could not be recovered after conclusion of the trial, and this participant was excluded from our imaging analyses. A summary of scanner types and PET acquisition parameters is detailed in eTable 1 in Magnetic resonance imaging processing methods and scanner characteristics are further detailed in the eMethods and eTable 1 in GRN variations were randomized and completed treatment . One patient randomized to 500 mg FRM-0334 experienced a serious AE , which was not felt to be related to the study drug in the opinion of the site investigator. Patients randomized to FRM-0334 experienced higher incidences of cardiac, constitutional, dermatologic, infectious, psychiatric, and respiratory symptoms and a lower incidence of gastrointestinal symptoms relative to placebo-treated participants  with gent AEs  was simiicipants .P = .56), CSF PGRN   after 28 days of treatment  A and B, reatment . AdditioP = .18) or Cmax  values on day 1. Compared with the low- dose cohort, the high-dose cohort also did not consistently experience higher AUC  or Cmax  values on day 7. Older age  predicted higher baseline AUC  and Cmax  , although day 1 and day 7 Cmax was not . In patients who received FRM-0334, change in PGRN (plasma and CSF) was not linearly related to change in bifrontal FDG-SUVR, CSF NfL, CSF Aβ1-42, CSF total tau, or measures of clinical severity, although an increase in CSF PGRN was associated with a decrease in p-tau181  , was associated with frontal FDG hypometabolism relative to controls , with additional left-predominant hypometabolism noted in lateral parietal, lateral temporal, posterior cingulate, caudate, and thalamic regions , greater Clinical Global Impressions Scale severity , lower Frontotemporal Dementia Rating Scale score , elevated CSF NfL , and high CSF t-tau , but was not linearly related to plasma PGRN, CSF PGRN, CSF Aβ1-42, or CSF p-tau181 . Greater clinical severity (CDR plus NACC FTLD sum of boxes) was linearly related to high CSF NfL, but not plasma PGRN, CSF PGRN, CSF Aβ1-42, CSF t-tau, or CSF p-tau181 . Moreover, the observed variance in FRM-0334 Cmax did not predict change in PGRN (plasma and CSF) or other exploratory PD measures, further suggesting inadequate target engagement. Additionally, given the unreliable relationship between FRM-0334 dose level, plasma Cmax, and plasma AUC, it is unknown whether alternative regimens (including higher or more frequent doses) of the current formulation could reliably improve the bioavailability of FRM-0334 in future trials. Given the relationship between FRM-0334 exposure and age, future early phase trials of other orally available HDAC inhibitors may require design considerations that account for possible unique, age-related differences in drug oral bioavailability in GRN haploinsufficiency. Given the wide distribution of GRN expression,29 particularly in the liver, it is possible that GRN haploinsufficiency could give rise to a wide array of subtle phenotypic differences in a variety of cell types, including peripheral cells mediating drug absorption or metabolism.The PD and PK profiles of oral FRM-0334 firmly suggest that further development of the tested formulation should not be pursued for 30 and anatomic descriptions of frontal hypometabolism31 in GRN haploinsufficiency but reveal novel fluid-biomarker relationships to FDG-PET data. Cerebrospinal fluid NfL is interpreted to be a biomarker of axonal injury and neuronal degeneration32 and correlates with disease severity34 and aggressiveness in sporadic FTLD as well as in GRN haploinsufficiency.35 The observed relationship with NfL level may attest to the synaptic loss and neuronal metabolism documented on FDG-PET (via astrocyte-neuron metabolic coupling36). Additionally, although GRN haploinsufficiency is not typified by tau deposition on autopsy, our findings support previous observations of elevated CSF t-tau in symptomatic disease.37 The relationship of FDG-PET to t-tau may reflect the lysosomal role of PGRN in supporting autophagy pathways,38 which may impact tau clearance.39 Fluorodeoxyglucose hypometabolism was not associated with CSF p-tau181, therefore, comorbid Alzheimer pathology is unlikely to have mediated its relationship to t-tau. It is unclear how much of our FDG-PET fluid-biomarker correlations were mediated by brain atrophy alone, given our lack of complementary harmonized magnetic resonance images. Our sensitivity analyses, accounting for whole-brain parenchymal volume, did provide some evidence that FDG hypometabolism tracks clinical GRN deficiency severity even after the effect of volume is considered.Our FDG-PET analyses were consistent with previous clinical correlations41 With regard to our FDG-PET analyses, the heterogeneity of our data  may have also limited the quality and resolution of our observations. Moreover, the short duration of our trial provided a relatively short interval to validly discern a true trajectory of change within our heterogeneous data set. Despite these limitations, our novel observations of FDG hypometabolism support further exploration of FDG-PET as an imaging biomarker of FTLD biological severity in future GRN haploinsufficiency studies .Our study had several limitations affecting its interpretability. The inconsistent bioavailability of FRM-0334 made it difficult to reliably extrapolate the broader effect of consistent HDAC inhibition in PGRN deficiency or whether higher exposure levels of FRM-0334 may have affected plasma PGRN. The small sample size of patients randomized to placebo and the relatively short duration of this trial also limited our ability to detect modest deflections in biomarker trajectory. However, recent publicly presented open-label trial data do suggest that a similar duration and smaller sample size may be sufficient to demonstrate biomarker evidence of target engagement from alternative PGRN boosting strategies.GRN haploinsufficiency, this trial demonstrates that international multicenter studies are feasible in this indication.6 Such multicenter trials provide a unique opportunity to collect valuable observational data in rare familial forms of FTD.In conclusion, this randomized clinical trial demonstrated that FRM-0334 did not have a PD effect on CSF or plasma PGRN concentration. However, this study provided useful data to inform future clinical trial methodology in similar cohorts. Given the rarity of patients with


Early detection of immune-related adverse events (irAEs) with immune checkpoint inhibitors (ICIs) is crucial, particularly when these are likely to mimic tumor progression, as well as sarcoid-like reactions. Here, we report the case of a 68-year woman, with a history of four primary cutaneous melanomas (thickest lesion with BRAF mutation removed from the left axilla 2 years before), who was diagnosed with BRAF V600E-mutant metastatic melanoma and treated by ICI targeting the PD-1 receptor. Follow-up whole-body positron emission tomography/computed tomography (PET/CT) using 18F-fluorodeoxyglucose ([18F]-FDG) was performed at 15 months, and FDG-avid subcutaneous nodules on her legs were detected. A biopsy from a lesion on her right leg was obtained, and histology strongly suggested erythema nodosum. Given the isolated nature of these lesions, the normal serum Angiotensin-Converting Enzyme and the context of ICI, an immune-related sarcoid-like reaction was retained as the most likely diagnosis. Recent literature in immune-oncology suggests that erythema nodosum could be directly related to ICI(s). Although erythema nodosum is a rare occurrence with imaging features overlapping with malignancy, it should be considered in the differential diagnosis of suspicious in-transit metastasis, especially when the patient is treated with ICIs and when lesions follow a bilateral distribution. In conclusion, nuclear medicine physicians should keep in mind this irAE when interpreting PET/CT scans in clinical practice in order to avoid false-positive findings.