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 Celldex Therapeutics (NASDAQ:CLDX) shot nearly 20% higher today after the company's drug Rintega (rindopepimut) received breakthrough therapy designation from the Food and Drug Administration.

So what: Rintega is intended to treat adults suffering from EGFRvIII-positive glioblastoma, and successful phase 2 studies on the drug gave the FDA enough evidence to approve the drug's high-priority status. Celldex CEO Anthony Marucci noted in a press release that glioblastoma patients "have extremely limited treatment options, with only three new drugs approved in more than 20 years." The breakthrough therapy designation means Rintega could represent a big advance over these existing drugs.

Now what: Glioblastomas are not common -- it is estimated that 20,000 to 200,000 new cases are diagnosed each year. However, the lack of viable treatment options, along with Rintega's breakthrough designation, highlight the potential for Celldex to succeed with its treatment. Celldex this year should begin a phase 3 study of Rintega encompassing 745 people. The company to date has received generally positive news on Rintega, but final approval is still a ways off. With this designation in place, Celldex's shares might have already leapt to levels near where they would end up if Rintega is eventually approved for sale, so there may not be substantially more upside to capture from this particular drug.

Alex Planes has no position in any stocks mentioned. The Motley Fool recommends Celldex Therapeutics. 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.