Genocea halts its antibiotic vaccine program after a Phase II failure

Genocea CEO Chip Clark

Genocea Biosciences' ($GNCA) vaccine for pneumococcal infection missed its goals in a Phase IIa trial, leading the company to pause development and shift its attention to a more promising effort in genital herpes.

The vaccine, GEN-004, failed to significantly improve the rate and density of pneumococcal colonization in a 98-patient trial, the company said, coming up short on both of its primary endpoints.

In the study, patients got three doses of either placebo or GEN-004 four weeks apart and were then inoculated with pneumococcus serotype 6B. Genocea's vaccine improved bacterial colonization by 22% and 25% versus placebo, the company said, and patients taking GEN-004 reported between zero and two colony-forming units--used to estimate breadth of infection--compared with one to 11 such units for those on placebo. However, neither result was statistically significant.

Genocea's shares tumbled more than 35% on the news Monday morning, and the company's market cap has fallen by nearly three-quarters since July.

Genocea is now working with its advisers "to determine a next step for this program," CEO Chip Clark said in a statement. "... At this time, we believe it is possible that future trials would require a change in some combination of dose, adjuvant or trial population to confirm any effect."

In the meantime, the company is removing GEN-004 from its immediate R&D plans and turning its full attention to GEN-003, a vaccine for genital herpes. Earlier this month, Genocea disclosed positive 6-month efficacy results from a 310-patient Phase II trial on GEN-003, and the company believes it's on track to begin late-stage development in 2017.

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