Vaccinex’s Phase Ib/II trial evaluating its Alzheimer’s disease treatment pepinemabin has met its primary endpoint, consolidating previous evidence of the therapy’s neurodegenerative efficacy in Huntingdon’s disease.

The topline results, announced at the ongoing Alzheimer’s Association International Conference (AAIC) being held in Philadelphia from 28 July to 1 August, demonstrated the anti-semaphorin 4D (SEMA4D) antibody was well-tolerated by patients with no serious treatment emergent adverse events (TEAE).

The SIGNAL-AD study was conducted at 16 clinical sites and involved 50 patients with early Alzheimer’s disease dementia.

The randomised double-blind, placebo-controlled study involved intravenous (IV) infusions of pepinemab administered every four weeks for 44 weeks. Half the group received Vaccinex’s candidate, whilst the other half received placebo.

The study was also evaluating pepinemab effects on brain metabolism. Vaccinex reported that its asset resulted in a statistically significant increase in FDG-PET signal in areas of the brain known to be affected by early disease progression. The increase in FDG-PET signal is an indicator that the drug is preventing decline in brain metabolic activity.

Other key secondary endpoints, including cognition tests, were not met with statistical significance. Vaccinex said the trial was not “sufficiently powered” to detect these changes.

Vaccinex’s asset has also been investigated in Huntington’s disease, with similar safety profile and brain metabolic activity effects.

Vaccinex’s CEO Maurice Zauderer said: “This positive data release suggests that pepinemab has the potential to benefit patients with mild cognitive impairment due to Alzheimer’s disease.”

“Alzheimer’s disease and Huntington’s disease share important pathological features and clinical symptoms, and we believe our approach of confirming similar treatment effects of pepinemab in these two different neurodegenerative diseases is strongly supportive of pepinemab as a potentially well-tolerated and effective treatment [for both diseases.]”

Between 12% to 18% of people aged 60 or older are living with mild cognitive impairment due to Alzheimer’s, according to estimates by the Alzheimer’s Association. Vaccinex states a drug that can slow progression of this could significantly extend a productive life for people at risk.

The company said there are “concerns about limitations” around Eisai and Biogen’s Leqembi (lecanemab) and Eli Lilly’s Kisunla (donanemab), highlighting adverse events.

However, Vaccinex will need to overcome the market domination that Leqembi and Kisunla currently occupy. Leqembi is estimated to generate sales of over $6bn by 2030, whilst Kisunla is forecast to see sales of over $3bn by the same year, according to analysis by GlobalData.