Simufilam is a first-in-class drug candidate targeting altered filamin A, a proteopathy in Alzheimer’s disease. The primary objective of this Phase 2 clinical trial was to evaluate the effects of simufilam on cerebrospinal fluid (CSF) biomarkers in Alzheimer’s disease patients. A secondary objective was to assess cognitive enhancement.
In a randomized, placebo-controlled trial conducted across 9 clinical sites in the US, 64 mild-to-moderate Alzheimer’s disease patients were randomized to simufilam 50 or 100 mg b.i.d. or placebo for 28 days. Clinical diagnosis was confirmed by CSF total tau/amyloid-beta1 − 42 (Aβ42) > 0.28. Co-primary endpoints were changes in CSF Aβ42, total tau, phospho-tau (P-tau181), neurogranin, neurofilament light chain, and YKL-40. Secondary endpoints included additional CSF biomarkers assessing neuroinflammation and blood brain barrier integrity, and tests of episodic and spatial working memory.
Adjusting for multiplicity of the six co-primary endpoints (p < 0.008 versus placebo required for significance), simufilam 50 and 100 mg significantly reduced CSF levels of total tau, hyperphosphorylated tau (P-tau181), neurogranin, neurofilament light chain and YKL-40. Simufilam 50 mg significantly increased CSF levels of Aβ42. On secondary CSF biomarker endpoints, both doses of simufilam significantly reduced IL-6, soluble TREM2 (triggering receptor expressed on myeloid cells-2), HMGB1 (high mobility group box-1), albumin and immunoglobulin G. All but one patient improved from baseline across biomarkers. Simufilam 50 and 100 mg showed effect sizes versus placebo (0.23–0.46) in change from baseline in episodic memory and spatial working memory. Episodic memory improvements correlated most strongly with decreases in P-tau181 (R2 = 0.48). Simufilam was safe and well tolerated. Target engagement was demonstrated by filamin A linkages to nicotinic acetylcholine receptor subtype α7 (α7nAChR) and toll-like receptor 4 (TLR4) in lymphocytes.
Simufilam was safe and well tolerated and significantly improved eleven CSF biomarkers in patients with Alzheimer’s disease, implying biological evidence of disease modification. Simufilam will be further evaluated in large, definitive clinical trials.
ClinicalTrials.gov Identifier NCT04079803.