Eli Lilly’s oral OGA inhibitor ceperognastat failed to slow early Alzheimer’s progression in the Phase 2 PROSPECT-ALZ trial despite favorable biomarker findings.
Written By: Mayuresh Salvi, PharmD
Reviewed By: Pharmacally Editorial Team
Ceperognastat, an investigational oral O-linked N-acetylglucosaminidase (OGA) inhibitor developed by Eli Lilly and Company, did not slow cognitive or functional decline in patients with early symptomatic Alzheimer’s disease in the Phase 2 PROSPECT-ALZ trial. Published online in JAMA on July 13, 2026, the study showed that neither tested dose achieved clinically meaningful improvement over placebo on the Integrated Alzheimer’s Disease Rating Scale (iADRS) after 100 weeks. The higher 3 mg dose was also associated with greater disease progression and a higher incidence of serious adverse events.
Scientific and Clinical Context
Despite recent advances in amyloid-directed therapies, Alzheimer’s disease remains a leading cause of dementia worldwide, and effective treatments targeting tau pathology remain an important unmet need. Abnormal tau accumulation closely correlates with neurodegeneration and clinical decline, making it an attractive therapeutic target. OGA removes O-linked β-N-acetylglucosamine (O-GlcNAc) modifications from tau proteins, a process associated with tau hyperphosphorylation and aggregation. Ceperognastat inhibits OGA, increasing O-GlcNAc-modified tau and reducing pathological tau accumulation in preclinical models, providing the rationale for clinical evaluation.
Trial Details and Key Findings
PROSPECT-ALZ (NCT05063539) was a multicenter, randomized, double-blind, placebo-controlled Phase 2 trial conducted across 72 sites in Australia, Canada, Japan, Poland, and the United States. The study enrolled 327 participants aged 60 to 85 years with early symptomatic Alzheimer’s disease, with the primary efficacy analysis focusing on 259 participants who had low-to-medium baseline tau burden confirmed by tau positron emission tomography. Participants received once-daily oral ceperognastat at 0.75 mg, 3 mg, or placebo.
The study did not achieve its primary objective. At week 100, posterior mean iADRS score changes were -8.39 with ceperognastat 0.75 mg, -13.27 with ceperognastat 3 mg, and -10.07 with placebo. The lower dose corresponded to an estimated 16% reduction in disease progression, whereas the higher dose was associated with 32% greater progression than placebo. Neither dose met the prespecified Bayesian probability threshold required to demonstrate clinically meaningful slowing of disease progression, reinforcing the negative primary outcome. No significant improvements were observed across secondary clinical endpoints, including ADAS-Cog13, Clinical Dementia Rating-Sum of Boxes (CDR-SB), Alzheimer’s Disease Cooperative Study-Activities of Daily Living (ADCS-iADL), and Mini-Mental State Examination (MMSE).
Despite the negative clinical findings, investigators observed evidence of biological activity. The 3 mg dose significantly slowed tau PET signal increase in the lateral temporal lobe, while both treatment groups demonstrated reduced whole-brain and hippocampal volume loss on volumetric MRI. Plasma biomarkers, including phosphorylated tau217 (p-tau217) and glial fibrillary acidic protein (GFAP), also showed favorable trends, indicating target engagement despite the absence of measurable clinical benefit. The disconnect between favorable biomarker changes and the lack of clinical improvement highlights the ongoing challenge of translating biological activity into meaningful patient outcomes.
Safety Profile
Overall treatment-emergent adverse events occurred at similar rates across study groups. However, serious adverse events were more frequent with the 3 mg dose, affecting 26.4% of participants compared with 15.7% in the placebo group, and severe adverse events were also more common. Clinically significant weight loss of at least 7% from baseline occurred in 34.0% and 38.9% of participants receiving ceperognastat 0.75 mg and 3 mg, respectively, compared with 14.8% of those receiving placebo. Two deaths occurred in the 3 mg group, although investigators considered both unrelated to study treatment.
Study Implications
The PROSPECT-ALZ findings underscore the complexity of Alzheimer’s drug development and raise important questions about whether modifying tau biology alone is sufficient to alter disease progression after symptoms emerge. Although ceperognastat demonstrated biological effects on imaging and fluid biomarkers, these changes did not translate into improvements in cognition or daily functioning.
Future Directions
The negative efficacy findings, together with the less favorable safety profile observed at the higher dose, are likely to inform future development strategies for ceperognastat and other tau-targeted therapies. The study also reinforces that demonstrating biological target engagement alone may not be sufficient and that future Alzheimer’s therapies must deliver measurable clinical benefit alongside biomarker improvements.
Reference
Ceperognastat in Early Symptomatic Alzheimer Disease A Randomized Clinical Trial