Sanofi has joined forces with US biotech Immune Design to accelerate development of the first therapeutic vaccine against genital herpes.
Despite decades of research, the Herpes simplex virus (HSV) that causes genital herpes has proved remarkably resistant to the development of an effective vaccine, which could have a dramatic impact in reducing the spread of the sexually-transmitted infection (STI).
Genital herpes is a recurrent, lifelong viral infection and while symptoms can be managed with antiviral drugs, patients tend to suffer recurrent outbreaks, in some cases several times a year. HSV is spread when patients have symptoms, so a key goal is to prevent outbreaks occurring.
Sanofi vaccines division Sanofi Pasteur and Immune Design both have candidates in early-stage testing but have decided to pool their resources, collaborating on the two vaccines in the hope that at least one proves worthy of further development.
Sanofi Pasteur is contributing its replication-defective HSV vaccine HSV-529 – which is already in clinical trials – while Seattle-based Immune Design is stumping up its preclinical trivalent vaccine G103 as well as a platform technology called GLAAS, which is designed to simulate a cellular immune response against infections.
By working together, the two companies may be able to shorten the gap with Vical and Agenus/Genocoa, which both have therapeutic HSV vaccines in mid-stage trials, and stay ahead of other rivals such as Tomegavax. All the companies are hoping to succeed where others have failed, notably GlaxoSmithKline that was forced to abandon its own Simplirix candidate in 2012.
HSV-529 is a stripped down virus that retains all the components of wild-type virus apart from two proteins that are involved in viral DNA replication. It infects cells that can stimulate an immune response, but cannot in theory reproduce and cause a latent infection.
It is currently being studied in a phase I trial sponsored by the US National Institutes of Health (NIH) in people with the infection as well as those without, with results expected in 2016.
Sanofi notes that genital herpes is the most common STI and affects around one in six people in the US, with many unaware they are carrying the virus.