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 Dynavax Technologies (NASDAQ:DVAX), a clinical-stage biopharmaceutical company focused on infectious and autoimmune disease, imploded, falling as much as 42% after reporting its findings from a meeting with the Food and Drug Administration over its biologic license application for hepatitis-B vaccine Heplisav.

So what: What's causing today's tumble is squarely in Dynavax's first line of the FDA's findings, "The safety database does indeed need additional subjects." This simple phrase means that an additional safety trial will need to be conducted before the FDA will even consider Heplisav for approval. That means more time and more money for Dynavax. The conclusion that additional trials would need to be run was reached on the basis that the existing data subset would have drastically limited its approval to a small amount of people. In addition to understanding what the FDA would like to see in additional safety trials, Dynavax also has manufacturing concerns to contend with as noted by the FDA in its complete response letter to the company.

Now what: Things just keep getting worse for Dynavax! With the company still needing to address its CRL concerns and now needing to run an additional safety trial, I suspect it could be another 18 months before Heplisav again sees the light of day. By then, Dynavax will have burned through what I suspect will be all of its remaining cash, forcing it to turn to a potentially dilutive secondary offering. If you haven't already thrown the caution tape around this situation, allow me to do so for you! I suggest being an innocent bystander and letting future data do the talking.

Craving more input? Start by adding Dynavax Technologies to your free and personalized watchlist so you can keep up on the latest news with the company.

Fool contributor 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.

Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.