The purpose of this study is to:

* Evaluate the safety and tolerability of intrathecal (IT) ALN-5288 in patients with Alzheimer's Disease (AD)
* Evaluate the pharmacodynamic (PD) and pharmacokinetic (PK) effects of ALN-5288 after dose administration

A Study to Evaluate ALN-5288 in Patients With Alzheimer's Disease

Alzheimer's Disease

NEUROLOGIC

Placebo

ALN-5288

Clinical Trial Site

A Phase 1, Randomized, Placebo-controlled Study With a Double Blind Period With Open-label Extension Period to Evaluate the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of Intrathecally Administered ALN-5288 in Adult Patients With Alzheimer's Disease

Participants will be administered ALN-5288 in the Double-blind (DB) Period and Open-Label Extension (OLE) Period.

Participants will be administered placebo in the DB Period and ALN-5288 in the OLE Period.