Repurposing Siponimod for Alzheimer's Disease

Collaboration with multiple sclerosis (MS) specialty colleagues led us to formulate the central hypothesis that Siponimod could lower the rate of brain atrophy in Alzheimer's disease (AD) subjects. To test our central hypothesis, we will carry out an 18-month Phase II, double-blind, randomized, twoarmed, placebo controlled, proof-of-concept clinical study in early AD subjects (i.e. mild AD) who will be receiving an escalating dose of Siponimod or placebo in the ratio 2:1 for 12 months, followed by a 6-month washout period. The primary outcome measures are safety and tolerability of Siponimod in mild AD subjects. The secondary outcome measures are the rates of brain atrophy derived from volumetric MRI (vMRI) as a proxy for neurodegeneration conducted at baseline, 6, 12, and 18 months. The tertiary outcome measures are the changes in cognition and the levels of AD-associated (e.g., Aβ and tau) and inflammatory biomarkers in CSF after Siponimod exposure. In an exploratory effort, we will also measure plasma inflammatory markers during the entire duration of the study to investigate whether one or more of these markers can be used as dynamic surrogate markers of treatment response. Using our unique experience with the repurposing of immunomodulatory drugs for AD (and NCT #04032626), in the present project we are using elements of clinical trial design that we believe were successful and made some adjustments to fit the pharmacologic and toxic properties of Siponimod.