The purpose of this study is to evaluate the safety, tolerability, pharmacodynamics (PD)
and pharmacokinetics (PK) of a single dose of ALN-HTT02.

A Study to Evaluate ALN-HTT02 in Adult Patients With Huntington's Disease

Huntington's Disease

Placebo

ALN-HTT02

Clinical Trial Site

A Randomized, Double-blind, Placebo-controlled Study, to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Intrathecally Administered Single Ascending Doses of ALN-HTT02 in Adult Patients With Huntington's Disease

Area Under the Plasma Concentration-time Curve (AUC) Maximum Observed Plasma
Concentration (Cmax) Time to Maximum Plasma Concentration (Tmax)

Participants will be administered a single dose of ALN-HTT02 during the Double-blind Part
of the study. Participants who received ALN-HTT02 in the Double-blind part of the study
will not receive an additional dose during the Open-label part of the study

Participants will be administered a single dose of placebo during the Double-blind Part
of the study. Participants will have the option to receive a single dose of ALN-HTT02
during the Open-Label Part of the study.