In March, I reported on the first ever herpes vaccine and its effectiveness in people who were infected with herpes. Data from trials of Genocea Biosciences' GEN-003 showed a modest, but real, effect in reducing symptoms and shedding (1) in people who were infected with HSV-2 (genital herpes).
Last month, I reported on Rational Vaccines' Theravax, which seemed to have significant advantages of 003; although, it is important to keep in mind that this conclusion was based on a Phase I clinical trial, which was conducted in St. Kitts on only 20 patients. My interview with Rational's CSO Dr. William Halford can be read here.
Last week, Genocea reported 12-month clinical data at the Infectious Disease Society of America (IDSA) annual meeting in New Orleans.
Although it is difficult to directly compare the two vaccines, the table below summarizes data from GEN-003 (at 6 and 12 months) and Theravax (September 2016).
Genocea is following standard clinical protocols to seek approval for 003 in the US, and its vaccine has been evaluated in more than 300 people. The vaccine, which is given once, is effective in reducing both the number of outbreaks and viral shedding but appears to offer no advantage over Valtrex (2), which is the current standard of care. Genocea has not announced a timeline for Phase III trials. Although 003 has certainly demonstrated efficacy, the data are not impressive. Furthermore, it does not protect against HSV-1, which -although often presumed to only cause "oral herpes" - can also cause genital herpes. In fact, in young women in the US, HSV-1 is responsible for more cases of genital herpes than HSV-2. The historical lack of success of synthetic vaccines is troubling.
Rational Vaccines is taking a very different, and unorthodox, route for Theravax, which requires three injections. The company is intentionally bypassing the FDA and is focusing on countries with less restrictive clinical trial requirements. Its plan is unorthodox—to provide the vaccine to as many HSV infected people as possible, and to do so very quickly. Furthermore, the data for Theravax are rather sparse; however, there are some indications that it will be superior to GEN-003, perhaps even by a large margin. At this time, the dearth of data require that any conclusions that are drawn must be done so with caution.But, the historical success of live attenuated vaccines is is probably the most important factor here.
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(1) Shedding is the time when virus is actively being produced, but no symptoms are present. People who are shedding are contagious.
(2) Valtrex is a pro-drug of acyclovir—the actual antiviral drug. For an explanation of how acyclovir works, see "How Do Herpes Drugs Work?" To learn how pro-drugs work, and why they are usually superior, see ADHD Sufferers—Pay Attention: Here's How Vyvanse Works.