Merck & Co has signed a deal potentially worth over 440 million euros to license AiCuris of Germany's portfolio of investigational medicines targeting human cytomegalovirus, notably the late-stage drug letermovir.

The latter is a potentially first-in-class antiviral derived from a novel chemical class, quinazolines,  and is now in Phase III for the treatment and prevention of HCMV infection in transplant recipients. Letermovir has received orphan drug status in the European Union and the USA, where it has also been granted fast-track designation.

Cashwise, AiCuris will receive a 110 million euro upfront fee and is eligible for milestone payments of up to 332.5 million euros based on the success of letermovir, an additional back-up candidate as well as other Phase I candidates. The Wuppertal-based group is also entitled to royalties.

Roger Pomerantz, head of licensing of the firm's infectious disease franchise at Merck Research Laboratories, said there is "a significant need for additional medicines for the treatment of HCMV infection", which is one of the most common viral infections affecting organ and bone marrow transplant patients. He said that AiCuris' portfolio complements Merck's broad antiviral portfolio.

Helga Rubsamen-Schaeff, chief executive of AiCuris, founded in 2006 as a spin-off from Bayer, said that Merck's "ongoing commitment to infectious disease research, combined with its experience in developing and marketing antiviral products, makes them an excellent partner".