Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Agenus (NASDAQ:AGEN), a clinical-stage biopharmaceutical company focused on developing immuno-oncology drug candidates, briefly spiked higher by as much as 27% this morning after reporting positive data from a phase 2 study involving investigational synthetic vaccine HerpV as a treatment candidate for patients with genital herpes simplex virus-2, or HSV-2. Shares have since given up the bulk of their gains and are now up around 2% as of this writing.

So what: According to its press release, a majority of patients demonstrated an immune response to HSV antigens following a series of vaccinations as well as a booster dose at the six-month mark. Specifically, Agenus notes that, "more than half of those vaccinated developed a robust anti-HSV cytotoxic T-cell immune response, and in those patients there was a statistically significant 75% reduction in viral load." Agenus also notes that HerpV demonstrated a durable reduction in viral shedding of roughly 14% following the booster shot, which was consistent with levels observed following the initial series of vaccines. Adverse events for the study were reported to mostly be mild and include flu-like symptoms and reactions around the injection sites.

Now what: This is certainly encouraging data considering how widespread the HSV-2 is according to the Centers for Disease Control and Prevention. However, I for one would hold off on Agenus until after a significantly larger phase 3 trial mainly because of the high p-value (p-values tell us how much chance could have played into the results) of 0.08 associated with its 34% reduction in viral load as reported in November. While viral shedding was statistically significant, the p-value associate with the viral load reduction was not nearly as impressive due to the possibility of chance affecting the results. It's quite possible HerpV could go on to be quite successful, but I'd rather mitigate my risk by sticking to the sidelines until we have a larger pool of data to dig into.

Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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