While several biotech stocks sold off today in a broader industry sell-off, two stocks in this sector fell today because of their own bad news. Geron (NASDAQ:GERN) tumbled by about 15% today, after The Mayo Clinic announced that the trial for Geron's cancer drug Imetelstat for the myelofibrosis indication is closed, though no efficacy data was released. More than 25% of the patients in the trial have now dropped out, which has investors in Geron spooked.

Pfizer (NYSE:PFE) also lost today, as the company's lung cancer drug Dacomitinib failed two phase 3 trials. The drug was unable to prolong overall survival rate over the placebo or progression-free survival against Tarceva.

In this video, Motley Fool health-care analyst David Williamson gives investors his thoughts on Geron and Pfizer today.