BOULDER, Colo.--(BUSINESS WIRE)--Clovis Oncology, Inc. (Nasdaq: CLVS) announced today that the underwriters of its recently completed initial public offering have exercised their option to purchase an additional 700,000 shares of Clovis Oncology common stock to cover over-allotments. The sale of the additional shares is expected to close on November 30, 2011, subject to customary closing conditions.