The sigma-2 (σ-2) receptor: a review of recent patent applications: 2013–2018

ABSTRACT

Introduction: The discovery of the sigma-2 receptor and the analogous sigma-1 receptor led to a decade-long quest to determine the true nature of this protein and novel ligands capable of modulating its activity. Despite this challenge, the sigma-2 receptor has been linked to several disease states, and multiple classes of sigma-2 ligands have been published in the 40+ years since its initial discovery.

Areas covered: This review covers newly published patent applications that describe sigma-2 receptor ligands capable of modulating disease states. The aforementioned documents entered the public domain as PCT patent applications between 2013 and 2018.

Expert opinion: In 2017, the sigma-2 receptor was positively identified as TMEM97 (transmembrane protein 97). The resolution of this ‘identity crisis’ will facilitate a greater understanding of the pharmacological role of sigma-2 receptor as well as support the identification of novel sigma-2 receptor ligands with potential utility as disease-modifying therapies.

KEYWORDS:

• Sigma-2
• patent
• sigma receptor
• TMEM97

Article highlights

• The sigma family of receptors was first identified in 1976, but the true nature of the sigma-2 receptor (σ-2) was unknown until it was positively identified as TMEM97 (Transmembrane Protein 97) in 2017.

• Compounds capable of binding to the sigma-2 receptor (σ-2) are currently under investigation as potential therapies for a variety of conditions including neurodegenerative diseases (e.g. Alzheimer’s disease), CNS disorders (e.g. depression) traumatic brain injury, pain, and cancer.

• A comprehensive review of PCT patent applications published between 2013 and 2018 that describe compound capable of binding to the sigma-2 receptor (σ-2) is provided.

This box summarizes key points contained in the article.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer Disclosures

A peer reviewer on this manuscript works on patent discussed in this manuscript. All other peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This article was not funded.