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 Five Prime Therapeutics (FPRX), a clinical-stage biopharmaceutical company focused on developing protein therapeutics to fight cancer and other inflammatory diseases, jumped as much as 22% after announcing a collaborative deal with Bristol-Myers Squibb (BMY 0.59%) before the opening bell.

So what: Under the terms of the deal, Bristol-Myers Squibb gets access to Five Prime Therapeutics' exclusive immuno-oncology platform and will decipher which therapies have the best chance of success based on two undisclosed immune checkpoint pathways. Bristol-Myers has the option of developing these cancer-fighting drugs as a single-agent therapies or can use them in combination with existing products in its own pipeline. Bristol-Myers will retain full worldwide rights to these therapies if approved.

For Five Prime, the company will receive a $20 million upfront payment from Bristol-Myers, is eligible to receive $9.5 million in researching funding over the course of its collaboration, and is getting a $21 million common equity investment from Bristol-Myers (representing a purchase of 4.9% of Five Prime's outstanding shares) at a 30% premium to Friday's closing price. In addition, it will also be eligible to receive milestone and development payments totaling as much as $300 million and tiered single-digit to double-digit royalties on any approved therapies.

Now what: Once again we see how incredibly hot cancer immunotherapies have become. A number of cancer-focused companies are realizing that it's easier to retrain the body's immune system to recognize cancer and attack it than to attempt to formulate a therapy designed to seek out cancer. It remains to be seen, of course, if this partnership will merit success, but Five Prime shareholders have to be pleased to have snagged an elephant in Bristol-Myers Squibb, which could go a long way to validating its proprietary drug discovery platform. From the standpoint of Bristol-Myers, it allows the company to potentially expand its immunotherapeutic research for a mere $50.5 million in costs, so it seems well worth the risk.