June 25 (Reuters) - An advisory panel to the U.S. Food and Drug Administration recommended on Wednesday that AstraZeneca Plc be required to submit further clinical data before its experimental ovarian cancer drug is approved.

The panel voted 11-2 that the company should complete a second trial to confirm results seen in a smaller trial which, while positive, were not robust enough to convince the committee that they could be reproduced.

Panel members also expressed concern about a potential increased risk of secondary cancers in patients receiving the drug, olaparib. The FDA is not obliged to follow the advice of its advisory panels but typically does so.

(Reporting by Toni Clarke in Washington; Editing by Bill Trott)