DIAN-TU Gantenerumab Open Label Extension: Results in Autosomal Dominant Alzheimer’s Disease

The Dominantly Inherited Alzheimer Network Trials Unit (DIAN-TU), sponsored by Washington University School of Medicine and collaborators including Hoffmann-La Roche and the Alzheimer’s Association, investigated gantenerumab, an anti-amyloid antibody, in individuals at risk for or with dominantly inherited Alzheimer’s disease (DIAD). This rare, early-onset form of Alzheimer’s is caused by genetic mutations and often runs in families. Previous double-blind DIAN-TU trials indicated that gantenerumab substantially reduced amyloid plaques and improved biomarkers, but failed to show clear clinical benefit. The open-label extension (OLE) was designed to further assess gantenerumab’s long-term effects on disease biomarkers, cognitive outcomes, and safety.

Target Engagement Achieved but Symptoms Persist

The OLE enrolled 73 participants (mean age ~49 years) who carried DIAD mutations. All received gantenerumab subcutaneously every two weeks, with follow-up over up to three years. The primary endpoint—change in amyloid burden measured by PiB-PET—demonstrated significant amyloid reduction at all timepoints (LS mean composite SUVR change at 156 weeks: -0.71; p<0.0001). Similarly, cerebrospinal fluid (CSF) biomarkers, including phosphorylated tau and amyloid beta ratios, showed favorable changes, suggesting target engagement and amyloid/tau pathology modification.

However, these biomarker benefits did not translate into significant slowing of cognitive or functional decline. Key secondary endpoints, including Clinical Dementia Rating–Sum of Boxes (CDR-SB), Mini-Mental State Exam (MMSE), and a cognitive composite, showed no statistically significant difference in disease progression compared to baseline rates. The trial also observed a high discontinuation rate and was ultimately terminated early following an interim analysis prompted by disappointing clinical results and the discontinuation of the gantenerumab program in sporadic Alzheimer’s disease.

Safety findings were consistent with prior studies, with injection site reactions and ARIA (amyloid-related imaging abnormalities) being the most frequent adverse events. No new safety signals were identified.

Redirecting Efforts Toward Broader Scientific Impact

Based on the lack of clinical efficacy despite robust amyloid lowering, the DIAN-TU group and its collaborators have terminated gantenerumab’s development in this setting. Efforts will now pivot to sharing the extensive biomarker and natural history data from DIAN-TU with the broader research community to inform the design of future prevention and treatment trials for both inherited and sporadic Alzheimer’s disease. Additionally, Washington University and its partners are expected to advance alternative therapeutic strategies targeting different disease mechanisms, leveraging ongoing genetic, biomarker, and cognitive datasets compiled from DIAN-TU cohorts. The publicly available data is expected to support innovation and collaboration for the next generation of Alzheimer’s disease research and interventions.