Yesterday, Rule Breakers pick Exelixis (NASDAQ:EXEL) held its annual research and development exposition day. For investors wanting a better understanding of the science behind Exelixis' drugs and the company as whole, the day-long presentation is a must-listen. Here is a CliffsNotes version of the conference call, for those with less time.

Not unexpectedly, Exelixis spent a large part of the meeting on its two most promising drug candidates -- XL647 and XL880. After successful phase 2 testing earlier in the year, XL647 wasn't picked up by partner GlaxoSmithKline (NYSE:GSK), but it will go into phase 3 testing for non-small cell lung cancer in the first half of 2008.

Among drugs in earlier stages of development, Exelixis expects to put two oncology-targeted compounds and one candidate for metabolic disease into later-stage preclinical testing in the first half of next year.

Three discovery-stage compounds developed in partnership with Bristol-Myers Squibb (NYSE:BMY) or in-house are expected to start phase 1 testing next year, nine will be in phase 2 with XL647, and two other compounds (XL184 and XL019) will start pivotal trials. Exelixis has also decided to at least temporarily halt development of three clinical-stage candidates including XL784, which is unlikely to be picked up by Glaxo.

During the conference call, Exelixis didn't give its cash-burn guidance for 2008, but it expects to hear back about whether partners like Glaxo and Genentech (NYSE:DNA) will take over development of five drug candidates next year. These opt-in decisions are important for Exelixis because if its partners choose to pick up these drugs, then it would get a cash payment and development costs for the compounds would be taken off its hands. This means Exelixis would have more resources to spend on its in-house candidates.

One interesting little piece of news was that Exelixis is running laboratory tests on some of its multi-targeted drugs together in combination therapy. One of the reasons Exelixis exists is that its multi-kinase targeting drugs would be more effective than competitors' therapies that attack only a single cancer target, so I guess Exelixis' thinking was that combination drugs made up of its products that already target more than one kinase would make a super cancer-fighting combination. We'll have to wait and see what safety issues such broadly targeted therapies have, though.

Nothing dramatic is set to happen to Exelixis in 2008. No pivotal phase 3 studies will be completed, and there are no Food and Drug Administration marketing decisions to wait for (probably a good thing, considering the state of the agency today). But just like this year, we'll likely get to watch another year of Exelixis' pipeline maturing nicely, with numerous early-stage data sets to mull over.

More Foolishness on drug developers:

Exelixis is a pick of our Rule Breakers newsletter. You can check out all our other recommendations with a 30-day free trial.

Fool contributor Brian Lawler does not own shares of any company mentioned in this article. GlaxoSmithKline is an Income Investor pick. The Fool's pipeline is stocked with a disclosure policy.