Today, shares of Portola Pharmaceuticals, Inc. (PTLA) fell by 30% after it announced that its oral anticoagulant drug betrixaban failed to produce significant results in a phase 3 study. The phase 3 study known as the APEX study tested patients using betrixaban against Sanofi (SNY) Lovenox -- enoxaparin. Betrixaban failed to produce significant results against injectable Lovenox -- standard of care -- in high risk patients. 

The company's drug did fare better in two other cohorts. The overall patient population metric, and another subset of high risk patients were older than 75 with elevated D-dimer. These two metrics were much better than Lovenox, but investors were still not satisfied with the results thus the stock falling 30%. 

There was no bleeding difference between Portola's drug betrixaban and Lovenox. The APEX results will be presented at the International Society on Thrombosis and Haemostasis (ISTH) Congress. This presentation will be held on Friday, May 27, 2016. The company will also submit the full data on the APEX study for publication in a medical journal.