Pharma

Herpes vaccine maker Genocea reports positive results a year after the first dose

Cambridge pharmaceutical maker Genocea remains at the head of the herpes vaccine pack, having newly released another […]

Cambridge pharmaceutical maker Genocea remains at the head of the herpes vaccine pack, having newly released another set of positive results for its experimental HSV2 vaccine. The company has found that its herpes vaccine is effective even a year after the initial dosage – cutting down the genital lesion and viral shedding rates substantially over a significant time period.

The company’s developing a genital herpes vaccine to be used in patients already infected with the disease. But it’d like to ultimately transition into developing a more prophylactic vaccine, CEO Chip Clark said.

Historically, pharmaceutical companies have developed antibody-based vaccines that center around B cell response – but that’s less useful in a disease that spends the bulk of its time hiding out in an infected person’s nerve cells.

“They had gone with what works: Taken what they thought were targets that B cells would recognize, and injected them as vaccines into people with HSV-2,” Clark said. “But they’ve shown nothing. While they’ve shown they can get an antibody response, it’s done nothing to affect the course of the disease.”

What Genocea – and competitors like Massachusetts-based Agenus and San Diego-based Vical – do differently is they awaken a T cell response, too. Genocea just released the final data from its Phase 1/2a study of GEN-003, the immunotherapy candidate for genital herpes.

The double-blind, placebo-controlled study ramped up the GEN-003 dosage over time, in an effort to determine proof-of-concept that the drug can indeed cut down the herpes viral shedding rate, along with the genital lesion rate. Right now, treatments like Valtrex only treat the clinical symptoms partially.

The new results report on the genital lesion rate a whole year after patient’s received their first dosage. Basically, the results show that while there are more lesions than at the six-month mark, a year after the three-vaccine sequence, there’s still a marked improvement in the presentation of the disease. At the six-month mark, for instance, there was a 65 percent reduction in lesion rate. At the year mark, there was a 42 percent reduction.

The most common side effects of the vaccine were fatigue, muscle aches, tenderness and pain of a largely mild or moderate intensity. No truly adverse events resulted. The company’s now in the midst of a Phase 2 trial to confirm that the 30 microgram dose is effective, as well as test additional dose combinations of its drug.

Here’s how that study was structured:

The patients filled in a diary for 28 days, and each day they had to note if they had a visible genital ulcer or lesion. Researchers used this baseline data as an individualized frame of reference to compare a patient’s progress over the course of treatment. Similarly, the study measured viral shedding by having a patient swab their genitals twice a day for the 28 days, which researchers examined for HSV2 DNA.

With a subject’s lesion and shed rate established, Genocea researchers randomly placed them into placebo or three different vaccine dosage groups. They were then inoculated at day 0, day 21 and day 42. There was no placebo effect here – this group had no improvement in viral shedding or lesion rate. But in the middle dose group – where patients were given 30 micrograms of the drug – there was the greatest drop in disease manifestation.

“In the two highest dose groups, something remarkable happened,” Clark said. “For the first time in HSV2, or in any infectious disease, we created something that could treat infection as a vaccination.”

Learn more about the developed of the genital herpes vaccine here.

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