Sigma-1 Receptor Ligand Blarcamesine (ANAVEX 2-73) for Alzheimer's Disease: A Systematic Review

Alzheimer's disease (AD) remains a major cause of dementia, and currently available therapies provide only modest clinical benefit or are limited by intravenous administration and treatment-related adverse effects. Blarcamesine (ANAVEX 2-73) is an orally administered sigma-1 receptor (S1R) agonist that has demonstrated neuroprotective effects in preclinical studies and has progressed through Phase I, Phase II and Phase IIb/III clinical trials. This systematic review evaluated the current clinical evidence for the efficacy and safety of blarcamesine in early-stage and mild-to-moderate AD.

A systematic literature search was conducted in PubMed (including MEDLINE), Scopus, and Google Scholar, together with clinical trial registries, with the final search performed in September 2025. Reference sections of manuscripts were searched, and authors were contacted for additional data. Studies investigating only blarcamesine in participants with mild-to-moderate AD were included. Blarcamesine for other diseases or severe AD were excluded. Data were summarised descriptively in accordance with PRISMA guidelines. The risk of bias was assessed using version 2 of the Cochrane Risk of Bias tool (RoB2) for randomised, placebo-controlled trials, and an adapted version of RoB2 for cross-over trials.

One Phase I first-in-human study in healthy volunteers and ten reports describing two randomised clinical trials (NCT02244541, a randomised open-label study, and NCT03790709, a randomized placebo-controlled study) and their associated open-label extension studies (NCT02756858 and NCT04314934) were identified, including two peer-reviewed manuscripts, two preprints, and six conference abstracts. Thirty-two participants were enrolled in the Phase IIa open-label dose-finding study, where outcome measures were compared to baseline (NCT02244541). In the extended open-label study exploring the cognitive effect for another 52 weeks, 21 of 32 remained in the study (NCT02756858). The randomised placebo-controlled trial (NCT03790709) enrolled 509 participants and randomised them into three groups: 167 treated with 30 mg blarcamesine, 168 treated with 50 mg blarcamesine and 168 treated with placebo (for 30 mg blarcamesine, 112 completed the study; for 50 mg blarcamesine, 90 completed the study; and for placebo, 136 completed the study). Subsequently, 300 of 509 participants remained in the open-label extension (NCT04314934). Across these two studies, blarcamesine was generally well tolerated, with adverse events that were predominantly mild, transient, and dose-related. Treatment was associated with slower cognitive and functional decline, improvements in multiple clinical outcome measures, and reduced brain atrophy in genetically defined subgroups. Participants carrying the SIGMAR1 and COL24A1 wild-type genotypes were associated with greater therapeutic benefit, supporting the potential value of pharmacogenomic patient stratification.

Current clinical evidence suggests that blarcamesine is a promising orally administered therapeutic candidate for early-stage AD with an acceptable safety profile and encouraging efficacy, particularly in genetically defined populations. However, the available evidence is derived from a limited number of clinical studies, including secondary analyses and conference reports. Additional independent randomised clinical trials are required to confirm these findings and further define the role of blarcamesine in the treatment of AD.

CRD420251142826.