Update (09/05/2017): AiCuris has started a Phase II trial, PRIOH-1, with the oral version of its herpes cure pritelivir. 

Update (17/01/2017): The company has presented results from its first Phase II trial with pritelivir. The drug candidate proved to work better than the antiviral drug valacyclovir, currently the standard of care.

Update (01/12/2017): AiCuris announced that it has begun Phase II trials.

Originally published on 24/08/2016

Cold sores plagued 67% of people under 50 in 2012. AiCuris is developing a cure, pritelivir, and it just cleared Phase I trials. It could be superior to treatments currently on the market.

Cold sores, known as recurrent labial herpes in medical speak, are painful and embarrassing for anyone unlucky enough to catch them. Moreover, they’re highly infectious, so if this is you, kiss responsibly. It’s little comfort that you’d be one of 3.7 billion people worldwide to be infected with them.

These sores are caused by herpes simplex virus 1 (HSV-1), whereas HSV-2 is the strain that causes their genital counterpart, which is as bad as it sounds. Fortunately, AiCuris is developing a cure for these viruses. Pritelivir reached its primary endpoint in Phase I as a topical treatment for HSV-1, outperforming those currently available (valacyclovir) without causing any long-lasting irritation. This trial will also be included as part of a second Phase II trial for an oral treatment targeting HSV-2.

Figure 1. A ThinPrep of herpes-infected squamous cell. These cells take their name from the latin word for fish or serpent scales and are found on the outer layer of the skin.

A herpes-infected squamous cell. These cells take their name from the latin word for fish or serpent scales and are found on the outer layer of the skin.

Both pritelivir and its predecessors work by inhibiting the virus’s helicase-primase complex. This effectively terminates DNA elongation prematurely, preventing the replication of the virus. Current standard HSV treatments have been nucleoside analogs (e.g. acyclovir and its prodrug valacyclovir), but pritelivir is a derived from a totally different class of small molecule as a thiazolylamide.

Since its foundation as a spin-off from Bayer, AiCuris has been focused on developing treatments and cures for infectious diseases, including hepatitis B, adenoviruses and human cytomegalovirus (hCMV), the latter in partnership with MSD. The company is also interested in neutralizing the threat of antibiotic-resistant pathogens like MRSA. To hear more about the company, check out our interview with the CEO last winter.

Images via P0/Public Domain, Yale Rosen/Flickr, ThinPrep/CC2.0, Ed Uthman/Flickr)

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  • Kate

    I read that the last trial for Pritelivir was supposed to occur in late 2016 and was to be presented to FDA for approval. I have not read any updates. Is this slated for release in 2017?


    • Haven’t heard anything yet! We’ll post something when we do.