Merck sets sights on Epstein-Barr virus jab with Opko deal

Merck & Co has entered into a worldwide licensing deal with Opko Health’s ModeX Therapeutics unit for a vaccine candidate against Epstein-Barr virus (EBV) that could be worth up to $922.5 million plus royalties.

Merck is taking over responsibility for clinical development and regulatory filings for the MDX-2201 shot, currently in preclinical development, for an upfront fee of $50 million, with the remainder tied to meeting development and commercial milestone targets.

EBV infects 95% of people and doesn’t usually cause health issues other than infectious mononucleosis – also known as mono or glandular fever – which typically affects teenagers and young adults and generally gets better in a few weeks without treatment.

After infection, the virus becomes latent in the body, however, and can be a trigger for some forms of cancer and multiple sclerosis. To date, no vaccine against it has been approved, and while several have been put into development over the years - including, notably, a GSK shot (GSK-268664) that reached phase 2 - all have failed to prevent EBV infection.

Hoping to do better, ModeX has developed a nanoparticle vaccine that contains four proteins used by the virus to gain entry into host cells, namely a recombinant antigen designed from the proteins gH, gL, and gp42, as well as an antigen derived from gp350. Most earlier vaccine attempts have targeted gp350 alone.

In animal studies, a similar vaccine candidate from ModeX generated neutralising antibodies in mice, ferrets, and nonhuman primates that inhibited EBV entry into both B cells and epithelial cells, and that dual mode of action is key to differentiating MDX-2201 from candidates that have come before.

The deal comes just a few months after Opko acquired ModeX – which was set up by former Sanofi R&D veterans Elias Zerhouni and Gary Nabel in 2020 – for $300 million in stock.

The company was formed to develop cancer immunotherapies, and drugs and vaccines for viral diseases, by combining natural protein structures to create multi-specific antibodies using technology licensed from Sanofi.

The companies said they will jointly advance MDX-2201 to an investigational new drug (IND) application filing seeking approval to start human testing, but didn’t give a timeline for that objective.

Merck said in a statement that it intends to develop MDX-2201 for protection against infection, as well as “other, potentially related conditions”.

If successful, the programme could be somewhat analogous to its work on blockbuster HPV vaccine Gardasil, targeting a virus that generally doesn’t cause acute illness itself, but predisposes to another disease, in this case cervical cancer.

Image by Willgard Krause from Pixabay