A phase 1B open‐labelled study of sodium selenate as a disease modifying treatment for possible behavioural variant fronto‐temporal dementia

Abstract

AbstractBackgroundThere are currently no approved disease‐modifying treatments of behavioural variant frontotemporal dementia (bvFTD), with the only treatments available providing symptomatic relief to secondary behavioural symptoms. Approximately 45% of bvFTD cases are tauopathies, with the main pathological hallmark and proposed pathogenic mechanism being the accumulation and aggregation of hyperphosphorylated tau. For this reason, hyperphosphorylated tau represents a promising target for a disease modifying treatment in this population. Sodium selenate stimulates the PP2A enzyme, which directly dephosphorylates hyperphosphorylated tau. This study investigated the use of sodium selenate as a disease‐modifying treatment for patients with bvFTD.MethodFifteen patients with possible bvFTD were treated with sodium selenate (15mg tds) for twelve months. Participants underwent a battery of cognitive and behavioural tests, MRI, lumbar puncture and safety assessments at screening, baseline, and at regular intervals following the commencement of treatment. Adverse events were monitored via diary cards between clinic visits.ResultFourteen patients are either on treatment or have completed the study. Interim safety analysis (9 completed patients, 5 on treatment) has shown that sodium selenate is safe and well tolerated, with no study withdrawals. Commonly reported adverse events are nail changes (n=5), fatigue (n=4) and nausea (n=4). No treatment related serious adverse events have occurred. An interim mixed‐effects analysis on all available neurocognitive data showed no statistically significant change in NUCOG total score (b=‐0.02, 95% CI = ‐0.18, 0.14]) or Carer Burden Scale (CBS) score (b =0.04, 95% CI = ‐0.05, 0.13]), CVLT total learning score (M diff = 5.80, 95% CI = ‐6.97, 18.57]), or NIH composite score (M diff = 4.72, 95%CI = ‐11.50, 14.70]). Percentage change in whole‐brain volume from baseline to 12 months ranged from ‐0.68% to ‐6.26% (n=5 <‐2%, n=2 ‐5‐6%).ConclusionThe interim results have shown that sodium selenate is safe and well tolerated in patients with bvFTD. Early indications show sodium selenate may be effective in reducing atrophy and halting cognitive decline in a subset of bvFTD patients. A larger phase 2 placebo controlled study is necessary to evaluate whether sodium selenate is efficacious as a disease modifying treatment of bvFTD.