A Phase 2 Trial of ALN-APP in Patients With Cerebral Amyloid Angiopathy

The purpose of the study is to evaluate the effect of ALN-APP on measures of CAA disease progression and to characterize the safety, tolerability, and pharmacodynamics (PD) of ALN-APP in adult patients with sporadic CAA (sCAA) and Dutch-type CAA (D-CAA). The study will be conducted over 2 periods: a 24-month double-blind treatment period and an optional 18-month open-label extension (OLE) period. The estimated duration of study participation, inclusive of screening, treatment, and additional safety follow-up, is up to 50 months.

Inclusion Criteria (sporadic CAA patients): * Is 50 years or older * Has probable CAA per the Boston Criteria Version 2.0 Inclusion Criteria (Dutch-type CAA patients): * Is 30 years or older * Has known E693Q amyloid precursor protein (APP) gene mutation for Dutch-type CAA Exclusion Criteria: * Moderate or severe stage Alzheimer's disease (AD) or significant cognitive impairment (CI) * Has a history of previous clinical intracerebral hemorrhage (ICH) with onset less than 90 days prior to anticipated randomization in the study * Has alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \>3×upper limit of normal (ULN) at Screening * Has estimated glomerular filtration rate (eGFR) \