Merck tries again in Alzheimer's with Teijin's tau antibody

Merck & Co is looking to improve its neurology pipeline via a deal with Teijin Pharma to develop a new tau-targeting antibody.

The tau protein is implicated in a number of nervous system diseases including Alzheimer’s - but the area remains very high risk, as at least one other tau-targeting protein has already failed.

Merck suffered a setback only recently in Alzheimer's with verubecestat , a late-stage BACE inhibitor developed in partnership with ALK-Abello, which failed in a mid-stage study.

Although Merck has decided to continue with an ongoing phase 3 study, there are serious doubts about verubecestat and the company is already looking to find other ways to combat the disease.

Investigational drugs from Eli Lilly and Pfizer/Elan targeting beta-amyloid also failed in trials, but pharmaceutical companies are still trying to develop new drugs -  as the financial rewards for medicines that slow or stop the disease's progress could be immense.

Biogen, for example, has taken a gamble on another amyloid-fighting drug, aducanumab, which is in phase 3 development.

Targeting tau is a less explored route – tangles of these proteins are also found in the brains of people with Alzheimer's and the hope is that tackling these will have a clinical effect.

However there has already been one failure - biotech company TauRx saw its drug LMTX fail in a phase 3 study of 800 patients with mild Alzheimer's disease.  While this drug is an oral 'tau aggregation inhibitor', Teijin's molecule is an antibody.

Under terms of the agreement Merck will have exclusive world-wide rights to develop, manufacture and market the anti-tau antibody. In exchange, Merck will make an upfront payment to Teijin Pharma, which is also eligible to receive development, regulatory and sales milestone payments.

Darryle Schoepp, vice president, neuroscience discovery, Merck Research Laboratories, said: “Merck remains committed to developing meaningful therapeutic options for the treatment of Alzheimer’s and other neurological diseases.”

Aside from verubecestat, Merck is also developing [18F]-MK-6240, a tau ligand being evaluated as a potential Positron Emission Tomography (PET) imaging agent for quantifying the brain burden of neurofibrillary tangle pathology in people with AD.

Meanwhile Axon Neuroscience has a tau-targeting therapeutic vaccine in its pipeline. In April it announced that the candidate, AADvac1, had shown some potential in a phase 1 trial in Alzheimer’s Disease and Frontotemporal Dementia (FTD).