Genocea’s Herpes Vaccine Heads For Critical Proving Ground
No one has made an effective vaccine for herpes simplex virus 2 (HSV-2), better known as genital herpes. That’s because no one has been able to harness the immune system to attack the virus while it’s hiding out, dormant, inside cells. While there’s a long road ahead, Genocea Biosciences says it has a shot to be the first—assuming the early immunologic signs it is seeing in a clinical trial end up translating into fewer symptoms of the chronic sexually transmitted disease.
Cambridge, MA-based Genocea is announcing some interim data from its first human clinical trial for its experimental vaccine, GEN-003, for HSV-2 today at the Interscience Conference on Antimicrobial Agents and Chemotherapy in Denver.
The results of the 143-patient study are positive, so far: Its vaccine appears to be well tolerated by patients, to trigger an immune system response, and slow down the rate at which the virus replicates in the body. But they’re also very preliminary: Genocea now has to play the waiting game and track these patients for a year to see if its scientific hypothesis actually translates to fewer of the outbreaks of genital blisters and sores that patients suffer from. If the results hold up over time, Genocea will gear up for its biggest test to date—a mid-stage clinical that will likely sink or swim based on GEN-003’s ability to confirm it can curb those symptoms.
GEN-003 is the first, most advanced product of Genocea’s quick-hit vaccine production platform. That technology, which came out of the labs of Harvard University professor Darren Higgins, is supposed to differentiate Genocea from other vaccine makers in two ways: significantly cutting down on the time it takes to discover the right antigens for a vaccine, which is important because antigens are the substances that people can form antibodies against. Genocea also envisions making vaccines that triggers a response from both B cells (the ones that form antibodies) and T cells. All of the approved vaccines to date work in a more limited way, by only coaxing B cells to fight viruses.
This, according to CEO Chip Clark, is the reason that no one to date has been able to make a vaccine that can treat—let alone prevent—HSV-2. While this virus spends some of its life cycle floating in the blood, where B cells can reach it, it spends more of its time hiding from those antibodies inside nerve tissue at the base of the spine, where it can grow and replicate. T cells, however, have the ability to recognize this infected tissue, if trained to do so, and kill the virus.
This is the type of thing Genocea hopes GEN-003 will be able to do. The experimental vaccine is a combination of both a B cell and T cell antigen, and an immune-boosting compound (adjuvant) called Matrix-M that Genocea licensed from Sweden-based Isconova AB. The idea is by triggering a T cell response, GEN-003 would hit HSV-2 while it’s seemingly dormant and tuckered away in cells—the time between HSV-2 patients’ outbreaks. By doing so, the vaccine, in theory, would slow down what is known as “viral shedding.” This is when HSV-2, after replicating in cells in the spinal column, migrates to the genitals.
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