Exelixis Must Pay Good Overtime

You don't have to be Snow White's stepmother, with a magic mirror on your wall, to get answers about which development-stage drugmaker has pushed the most molecules into clinical testing in the past three years. Simply look at Rule Breakers pick Exelixis (Nasdaq: EXEL  ) , which has fourteen compounds in (or about to begin) human clinical testing.

Yesterday, Exelixis announced that it was sending its fourth drug candidate into the clinic since the start of the year. At this rate, in five more years, Exelixis will have a clinical-stage drug pipeline as big as that of biotech powerhouse Genentech (NYSE: DNA  ) . A pipeline of more than 50 compounds in development is completely unfeasible for Exelixis at this point, but I'd guess that either the company's scientists are getting paid by the molecule, or Exelixis has some pretty powerful drug screening technology.

The allure of Exelixis' technology has drawn partnerships with more than one of the big pharmas. These partnerships could begin to yield fruit later this year, when GlaxoSmithKline (NYSE: GSK  ) must decide whether to take over development of Exelixis' lead cancer compound, XL647.

It's tough to judge whether Glaxo will choose to continue developing the compound. There is room for only so many targeted cancer therapies, considering that many of the types of cancer against which XL647 could be used are already treated with other compounds, and thus won't be multibillion-dollar market opportunities. In addition, Glaxo already has its own targeted cancer therapies like Tykerb, which inhibits some of the same molecular targets as XL647.

But it's important to remember that even if Glaxo decides not to fund XL647, that doesn't mean the compound's anything close to dead. Exelixis could choose to continue development of XL647 on its own, or partner it out to another pharma looking for a compound with proven cancer targets. Considering these alternatives, it's not even clear that having Glaxo pick up the drug would be the best outcome for Exelixis in the long run.

Either way, Exelixis is obviously not betting the house on any one compound. With so many drug candidates in or about to begin human testing, there will surely be more failures and setbacks ahead. For investors who haven't gotten their hands on the abstracts ahead of time, there will be a lot more data on these drugs to analyze next week, when Exelixis presents at ASCO and gives a conference call to discuss this data. Investors should stay tuned.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. GlaxoSmithKline is an Income Investor recommendation. The Fool has a disclosure policy.