Aribio said on the 16th that an interim analysis of its domestic phase 2a trial of AR1005, a candidate treatment for Lewy body dementia, showed simultaneous improvements in cognitive fluctuation symptoms and quantitative electroencephalography (qEEG) markers.
The findings were presented at the Alzheimer's Association International Conference (AAIC 2026), held in London from Aug. 12 to 15 local time.
AR1005 is a Lewy body dementia treatment candidate that Aribio is developing for the global market following its oral Alzheimer's drug AR1001. It is being developed as an oral combination therapy that improves cognition by modulating neuronal hyperexcitability.
Lewy body dementia is the second most common cause of degenerative dementia after Alzheimer's disease, presenting with a combination of cognitive decline, cognitive fluctuations, REM sleep behavior disorder, visual hallucinations, and Parkinsonian symptoms. It is characterized by "Lewy bodies," formed by the abnormal accumulation of alpha-synuclein protein in brain neurons. An estimated 1 million patients are in the United States alone.
There are currently no approved therapies indicated for Lewy body dementia.
This phase 2a study of AR1005 is underway at Yonsei University Severance Hospital in 60 patients with Lewy body dementia. The interim analysis included 20-week dosing data from 31 patients, about half the target enrollment.
The analysis found a statistically significant improvement in cognitive fluctuations, a hallmark symptom of Lewy body dementia.
On the Mayo Fluctuations Scale, which assesses cognitive fluctuations, the adjusted mean score was 0.77 in the AR1005 group, significantly lower than 1.92 in the control group (p=0.030).
This indicates that patients who received AR1005 experienced fewer episodes of sudden declines in concentration, reduced responsiveness, and clouded consciousness than those in the control group.
Positive changes were also observed in qEEG, an objective biomarker.
The theta-to-beta ratio, which reflects declining brain function and EEG slowing, decreased significantly in the AR1005 group versus the control group across whole-brain, central, and occipital regions. Because both the cognitive fluctuation symptoms experienced by patients and the objective EEG markers improved together, the results are said to support AR1005's early therapeutic potential.
Signals of improvement also appeared on the Clinical Dementia Rating–Sum of Boxes (CDR-SB), which evaluates cognition and activities of daily living. At week 20, the AR1005 group improved by 0.46 points versus the control group. From baseline, the control group worsened by 0.34 points, while the AR1005 group improved by 0.16 points, showing divergent trajectories.
On cognitive function (K-MMSE) and neuropsychiatric behavior (CGA-NPI) assessments, the AR1005 group also showed a consistent direction of improvement over the control group. However, the company noted that, given the limited number of patients analyzed so far, these measures did not reach statistical significance.
The researchers said the study achieved statistical significance in cognitive fluctuation and qEEG, and showed a consistent improvement trend across cognitive, functional, and behavioral assessments, making it a meaningful result for a proof-of-concept clinical trial.
The company said that because this was an interim analysis conducted before full enrollment was completed, final efficacy and safety will be determined after the trial is finished in all 60 patients.
Yeh Byung-seok, a neurology professor at Yonsei University Severance Hospital and the principal investigator, said, "Lewy body dementia presents with combined cognitive decline, severe cognitive fluctuations, visual hallucinations, and Parkinsonian symptoms, yet there is a lack of drugs that can treat these comprehensively."
Yeh said, "This interim analysis confirmed statistically significant improvements in cognitive fluctuations and qEEG markers, and other clinical measures also showed a consistent direction of improvement, providing important early evidence to assess AR1005's therapeutic potential."
Chung Jae-joon, CEO of Aribio, said, "While advancing the global development and commercialization preparations for the Alzheimer's treatment AR1001, we have also continued developing AR1005 in the Lewy body dementia field, where there are no treatment options. Based on this interim analysis, we will refine the design of global phase 2/3 trials and regulatory strategy to accelerate commercial development."