Investigational drugs targeting 5-HT6 receptors for the treatment of Alzheimer's disease.

INTRODUCTION

There are significant efforts invested into the discovery and development of novel treatments for Alzheimer's disease. While current discovery efforts and most scientific discussions seem to focus on disease-modifying therapy, there are several symptomatic therapy approaches that are being actively pursued. The goal of this review is to summarize the recent developments in the field of 5-HT6 receptor antagonists, a principle that has been extensively characterized preclinically and is now undergoing critical phases of clinical development.

AREAS COVERED: The article covers the current status of 5-HT6 receptor antagonists in clinical development. It also discusses the underlying mechanisms for the observed procognitive effects. The article is based on a search for investigational drugs using the key words '5-HT6', 'cognition', 'dementia', 'Alzheimer's disease', 'Phase II' and 'Phase III' in various databases and from conference abstracts.

EXPERT OPINION: After some period of little or no development activities, the field of 5-HT6 receptor antagonists attracted a lot of attention with three companies (GSK, Pfizer and Lundbeck) confirming aggressive development plans and initiating pivotal Phase II and III studies. These studies will be critical to prove that 5-HT6 receptor antagonists have a symptomatic efficacy profile that can be differentiated from that of currently used agents (cholinesterase inhibitors and the NMDA-antagonist memantine). Furthermore, there are several sets of data that point at a disease-modifying potential of this class of agents and these effects are likely to receive critical exploration if the ongoing symptomatic trials bring 5-HT6 antagonists closer to clinical use.