Herpes simplex virus (HSV)
In HSV, says Dr. Tyring, vaccines under development are truly therapeutic, not preventative. "Three different pharmaceutical companies have made molecular copies of HSV proteins that we are giving patients with recurrent genital herpes to boost their immunity." These projects include:
- GEN-003 (Genocea Biosciences), in Phase 2
- HerpV (Agenus), in Phase 2
- VCL-HB01 and VCL-HM01 (Vical), in Phase 1 and 2
Other products in development target the virus' helicase-primase complex, he says, which allows them to work against viral strains that are resistant to traditional therapies on the market.1
"In other words, acyclovir, valacyclovir, and famciclovir all have the same problem with resistance in certain viruses that have mutations or deficiencies of an important enzyme, thymidine kinase." However, he says that helicase-primase inhibitors including pritelivir (AiCuris) block an earlier stage of viral replication. "That's important for our immunocompromised patients, so we will have something that will benefit them on the market someday if they develop resistance." Pritelivir already has demonstrated efficacy and safety in this population, he says.
Additionally, a clinical trial reported by Dr. Tyring last year showed pritelivir to be significantly better than valacyclovir in reducing viral shedding and outbreaks among HSV-2-infected patients with genital herpes.2