UPDATE 1-FDA denies approval of Watson prostate cancer drug

* FDA seeks clinical testing, manufacturing info

* Watson working to provide requested info

* Shares down 9 cents

NEW YORK, July 14 (Reuters) - Watson Pharmaceuticals Inc
(WPI.N) said U.S. health regulators will require additional
information before approving a new, longer-acting formulation
of its prostate cancer drug Trelstar.

The U.S. Food and Drug Administration, in a so-called
complete response letter, requested clarification on clinical
testing, chemistry, manufacturing and controls of the 24-week
formulation of the testosterone-suppressing medicine. The
agency is also seeking further information on Watson's
third-party manufacturing of the injectable drug, the company
said.

Watson said it was working "expeditiously" to provide the
requested information.

Trelstar, which was developed by Swiss-based Debiopharm
Group, is already available in four-week and 12-week
formulations. The drug is used to treat advanced prostate
cancer in patients for whom removal of the testicles or
estrogen therapy is not feasible.

The new 22.5 milligram formulation suppresses testosterone
production continuously for 24 weeks, lasting twice as long as
Watson's current long-acting version of Trelstar.

Watson shares dropped 9 cents to $33.43 in midday trading
on the New York Stock Exchange.
(Reporting by I-Ching Ng, editing by Matthew Lewis)