RT Journal Article SR Electronic T1 Effects of IONIS-HTTRx in Patients with Early Huntington’s Disease, Results of the First HTT-Lowering Drug Trial (CT.002) JF Neurology JO Neurology FD Lippincott Williams & Wilkins SP CT.002 VO 90 IS 15 Supplement A1 Tabrizi, Sarah A1 Leavitt, Blair A1 Kordasiewicz, Holly A1 Czech, Christian A1 Swayze, Eric A1 Norris, Daniel A. A1 Baumann, Tiffany A1 Gerlach, Irene A1 Schobel, Scott A1 Smith, Anne A1 Lane, Roger A1 Bennett, C. Frank YR 2018 UL http://n.neurology.org/content/90/15_Supplement/CT.002.abstract AB Objective: To characterize safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of IONIS-HTTRx, an antisense oligonucleotide (ASO) designed to target huntingtin (HTT) mRNA, in patients with early manifest Huntington’s disease (HD).Background: HD is an autosomal dominant neurodegenerative disease caused by CAG repeat expansion in the HTT gene resulting in polyglutamine expansion in the mutant huntingtin protein (mHTT) with a toxic gain-of-function disease mechanism. No disease-modifying treatments are currently available. In transgenic rodent models of HD, suppressing HTT production delays disease progression and reverses disease phenotype (Kordasiewicz et al. 2012; Stanek et al. 2013). A comprehensive drug discovery effort, including extensive preclinical testing, was undertaken to design a well-tolerated ASO with high specificity to human HTT mRNA that potently suppresses HTT production.Design/Methods: In this first-in-human, multi-center, double-blind clinical trial (NCT02519036), 46 patients were randomized (3:1) to receive four doses of IONIS-HTTRx or placebo by monthly bolus intrathecal (IT) injection followed by a 4-month untreated period. Five ascending-dose cohorts were enrolled with independent Data Safety Monitoring Board review of safety, PK and target engagement prior to dose escalation.Results: IONIS-HTTRx was well-tolerated at all doses tested. Adverse events were mostly mild and unrelated to study drug. There were no adverse trends in laboratory parameters. No patients prematurely discontinued from treatment. ASO was measurable in CSF and plasma, and concentrations were generally aligned with predictions from a linked PK/PD preclinical model. Significant, dose-dependent reductions in CSF mutant HTT (mHTT) were observed.Conclusions: ASO technology has the potential to provide disease-modifying benefits to patients with neurodegenerative diseases. In this Phase 1/2a trial in early stage HD patients, IONIS-HTTRx delivered via IT injection was well tolerated with no study drug-related adverse safety signals during the treatment or follow-up periods. Significant dose-dependent reductions in CSF mHTT were observed, suggesting that IONIS-HTTRx is a promising therapeutic for the treatment of HD.Study Supported by: Ionis PharmaceuticalsDisclosure: Dr. Tabrizi has nothing to disclose. Dr. Leavitt has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Roche, Ionis, uniQure, Teva, Lifemax. Dr. Leavitt has received personal compensation in an editorial capacity for Editor-in-chief of the Journal of Huntington’s Disease. Dr. Leavitt has received research support from Teva, uniQure, Lifemax. Dr. Kordasiewcz has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Ionis Pharmaceuticals. Dr. Swayze has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Ionis Pharmaceuticals. Dr. Norris has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Ionis Pharmaceuticals. Dr. Baumann has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Ionis Pharmaceuticals. Dr. Smith has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Ionis Pharmaceuticals. Dr. Lane has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Ionis Pharmaceuticals. Dr. Bennett has nothing to disclose.