Biotech minnow takes over GSK Alzheimer’s drug

Bermuda-based biotech Roivant Neurosciences has licensed rights to an Alzheimer’s disease candidate developed by GlaxoSmithKline (GSK) and is planning to start pivotal trials in 2015.

The drug in question – called SB742457 – is a selective serotonin 5-HT6 receptor antagonist and, according to Roivant, has “the potential to improve cognition and function in multiple central nervous system disorders”.

GSK has already conducted 13 clinical trials of SB742457 involving over 1,250 healthy subjects and Alzheimer’s disease patients, with data to date providing “strong evidence that SB742457 holds promise for patients with mild-to-moderate Alzheimer’s disease”.

Roivant has not revealed how much it is paying for rights to the drug, but described it as “a foundational late-stage clinical asset” for the company, which intends to meet with the US FDA next year to discuss the design of late-stage studies.

Drugs that target neurotransmitters have been pushed out of the limelight somewhat by compounds that have tried to address proposed underlying disease mechanisms in Alzheimer’s disease, notably amyloid-busting drugs as well as those targeting tau protein.

First-generation drugs such as the cholinesterase inhibitors – a class which includes Eisai/Pfizer’s Aricept (donepezil) – are considered to have limited efficacy, but studies show they can sometimes buy a little time for patients with milder forms of dementia.

Serotonin is known to be reduced in patients with Alzheimer’s disease, particularly in areas of the brain associated with cognition, such as the cortex and the hippocampus. Blocking 5-HT6 receptors may improve cognition and memory by inhibiting the activity of other neurotransmitters that dampen down brain activity.

In a phase II trial, SB742457 given alongside Aricept seemed to provide an improvement in efficacy versus Aricept alone using memory and cognition scores. The drug is lagging a little behind Lu AE58054, a rival 5-HT6 inhibitor from Lundbeck and Otsuka which started phase III trials in October 2013.

While SB742457 and Lu AE58054 may not provide the leap forward in therapy desperately needed in Alzheimer’s disease, the chances of success are considered higher than for amyloid-targeting drugs, which so far have failed to show any benefit in clinical trials.

Roivant is headed by healthcare investor Vivek Ramaswamy, who co-managed one of the hedge fund industry’s largest biotech-focused portfolios at QVT Financial.

The company’s scientific programme is run by former Eisai executive Lawrence Friedhoff, who led the development of widely-used Alzheimer’s therapy Aricept (memantine).


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