APOLLOE4 Phase 3 study of oral ALZ-801/valiltramiprosate in ε4/ε4 homozygotes with early Alzheimer's disease: Trial design and baseline characteristics.

INTRODUCTION

The approved amyloid antibodies for early Alzheimer's disease (AD) carry a boxed warning about the risk of amyloid-related imaging abnormalities (ARIAs) that are highest in apolipoprotein E () ε4/ε4 homozygotes. ALZ-801/valiltramiprosate, an oral brain-penetrant amyloid beta oligomer inhibitor is being evaluated in ε4/ε4 homozygotes with early AD.

METHODS

This Phase 3 randomized, double-blind, placebo-controlled, 78-week study of ALZ-801 administered as 265 mg twice per day tablets, enrolled 50- to 80-year-old homozygotes with Mini-Mental State Examination (MMSE) ≥ 22 and Clinical Dementia Rating-Global Score 0.5 or 1.0. The study is powered to detect a 2.0 to 2.5 drug-placebo difference on the Alzheimer's Disease Assessment Scale 13-item Cognitive subscale primary outcome with 150 subjects/arm. The key secondary outcomes are Clinical Dementia Rating-Sum of Boxes and Instrumental Activities of Daily Living; volumetric magnetic resonance imaging and fluid biomarkers are additional outcomes.

RESULTS

The APOLLOE4 Phase 3 trial enrolled 325 subjects with a mean age of 69 years, 51% female, MMSE 25.6, and 65% mild cognitive impairment. Topline results are expected in 2024.

DISCUSSION

APOLLOE4 is the first disease-modification AD trial focused on ε4/ε4 homozygotes. Oral ALZ-801 has the potential to be the first effective and safe anti-amyloid treatment for the high-risk ε4/ε4 population.

HIGHLIGHTS

The APOLLOE4 Phase 3, placebo-controlled, 78-week study is designed to evaluate the efficacy and safety of ALZ-801 265 mg twice per day in early Alzheimer's disease (AD) subjects with the apolipoprotein E () ε4/ε4 genotype.The enrolled early AD population ( = 325) has 51% females, a mean age = 69 years, and a mean Mini-Mental State Examination = 25.6, with the majority being mild cognitive impairment subjects, a similar disease stage to the lecanemab Phase 3 AD trial (Clarity AD).The primary outcome is the cognitive Alzheimer's Disease Assessment Scale 13-item Cognitive subscale, with two functional measures as key secondary outcomes (Clinical Dementia Rating-Sum of Boxes, Amsterdam-Instrumental Activities of Daily Living), and with hippocampal volume and fluid biomarkers as additional outcomes.The study is unique in allowing a large number of microhemorrhages or siderosis at baseline magnetic resonance imaging, lesions that indicate concomitant cerebral amyloid angiopathy (CAA).At baseline, 32% of the enrolled population had at least 1 microhemorrhage, 24% had 1 to 4, and 8% had > 4 microhemorrhages; 10% had at least 1 siderosis lesion; with more males than females having microhemorrhages (63% vs. 37%) and siderosis (68% vs. 32%).Study results will become available in the second half of 2024 and, if positive, ALZ-801 may become the first oral drug to demonstrate a favorable benefit/risk profile in ε4/ε4 AD subjects.