Arena Pharmaceuticals shares rallied Monday, however, shares of Dendreon Corp. tumbled 4.68% to $28.72.
The biotech company said that Medicare was reviewing the effectiveness of newly approved product Provenge for the treatment of certain types of prostate cancer.
Dendreon: Medicare reviewing Provenge coverage, Medicare administrators say they will take a full year to review Dendreon Corp.'s prostate cancer therapy Provenge and decide whether to cover the costly treatment.
Shares of Seattle-based Dendreon fell $2.20, or 6.8 percent, to close at $30.13. The stock fell as much as 13.4 percent earlier in the session.