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 biopharmaceutical company Celldex Therapeutics (NASDAQ:CLDX) soared 18% today after reporting positive data from a phase 1 study of its experimental cancer therapy CDX-1127.

So what: Celldex shares have plunged in recent weeks on valuation concerns, but today's positive results are reigniting optimism over CDX-1127's blockbuster potential. Specifically, the data suggests an excellent safety profile and shows strong signs of clinical activity in advanced refractory patients, prompting investors to buy into the story on the hopes of even more good news ahead.

Now what: Celldex will present the data at the 2013 Society for Immunotherapy of Cancer annual meeting, which runs from today through Sunday.

"While future data from the expansion cohorts will be important to understanding single-agent activity," Chief Medical Officer Thomas Davis, M.D., said, "we are confident based on the dose-escalation data we have seen to date that we are well positioned to initiate combination studies of CDX-1127, with a particular interest in immune modulators."

Of course, with Celldex shares up a whopping 420% over their 52-week lows, Fools will need plenty of biotech expertise to estimate just how much of that potential is already baked into the valuation.