Let's take a look at today's top stories in biotech and health care. Keep an eye out for Exelixis (EXEL 0.54%)Geron (GERN -1.29%), and Vertex Pharmaceuticals (VRTX 1.33%) today.  

Exelixis set to release first quarter results today
Normally, earnings season for developmental biotechs is basically meaningless, as these companies tend to be cash consumers, not generators, at this stage in their life cycle. And indeed, the little know biopharma Exelixis largely fits this description, as consensus estimates peg the company losing $0.37 a share on a mere $6.11 million in revenue, for the first quarter. Yet, there are good reasons to listen in to Exelixis' conference call today. 

First and foremost, you should keep an ear open for any clinical updates for Exelixis's experimental prostate cancer drug Cometriq. As a reminder, Exelixis' shares spiraled downward when the drug's trial wasn't halted early for efficacy reasons. With Exelixis shares still down close to 50% for the year, investors will be keen to hear any updates on the trial's progress. And although Cometriq's prostate cancer trials are sure to grab the headlines, the drug's other ongoing late-stage trials for liver and kidney cancers shouldn't be forgotten. Indeed, I believe Cometriq's other indications have been overlooked by this moody market, yet they provide compelling reasons to think Exelixis could blaze the comeback trail in the near future. In sum, you may want to dig deeper into this under-loved biotech.   

Will Geron give a clinical update today?
Clinical-stage biotech Geron is scheduled to release earnings today and like its peer Exelixis, all eyes will be on its clinical program, not earnings. For investors new to this story, Geron is developing a telomerase inhibitor known as imetelstat as a treatment for a diverse array of hematologic myeloid malignancies. However, Geron's shares have cratered by 58% this year after the Food and Drug Administration placed a clinical hold on imetelstat due to serious adverse events arising in some of the drug's trials. 

What's important to understand is that Geron's managment didn't have to schedule a conference call to update investors. Per the Street's estimates, Geron is only expected to lose $0.06 per share on $460,000 in revenue. Those numbers are hardly worth a conference call in their own right. My view is that Geron will likely provide some form of clinical update for imetelstat on today's call, giving investors good reason to keep tabs on this stock today.

Will earnings boost Vertex shares today?
Like most biotechs, Vertex is having a tough year, with shares falling about 9% year to date. So investors are hoping a stronger than expected earnings report can reverse this trend.

Wall Street's consensus has Vertex posting a loss per share of $0.68 on $134.36 million in revenue. What's important to keep tabs on today for Vertex is sales of its cystic fibrosis drug Kalydeco, as well as those of its hepatitis C drug Incivek. Vertex's hope is that Kalydeco revenues can begin to compensate for the dramatic decline in sales of Incivek, following the launch of Gilead's Sovaldi.

As a reminder, Incivek was once a star drug in its own right, but sales crashed by 91% following the launch of Sovaldi. Now that Sovaldi has been on the market for over a full quarter, we should get a much better feel for the drug's ability to compete in the hepatitis C market, per today's earnings release. And we should gain a fair amount of insight into Kalydeco's ability to make up for lost revenue.

What's my take? I think Vertex is still overvalued at current levels. My estimates have annual revenue coming in at around $560 million, following the decline in Incivek sales. As such, Vertex shares might still be trading at close to 30 times annual revenue despite the stock's recent decline. So, you may want to take a wait and see approach with this biotech.