UPDATE 1-Pfizer's Sutent fails breast cancer study

* Pfizer says trial stopped after panel assesses trend

* Says other breast cancer trials under way

* Shares up in premarket trade

NEW YORK, April 2 (Reuters) - Pfizer Inc (PFE.N) on Thursday said it has stopped a late-stage study of its drug Sutent among patients with advanced breast cancer due to apparent lack of effectiveness, but is continuing with other studies among the hard-to-treat population.

Sutent, a pill currently approved for kidney and stomach cancer, was being tested in the trial against Xeloda (capecitabine), an oral medicine sold by Roche Holding AG (ROG.VX) that is often used to treat advanced breast cancer.

New York-based Pfizer said the Phase III study was stopped after an independent data monitoring board determined Sutent was unlikely to prove better as a stand-alone treatment than Xeloda among patients who had not previously benefited from standard treatments.

The trial was designed to assess whether patients taking Sutent could survive longer without a worsening of symptoms than patients receiving Xeloda.

"We remain fully committed to studying Sutent in advanced breast cancer," said company spokesman Jack Cox, who noted that three other Phase III trials and two mid-stage trials are under way in advanced forms of the cancer.

Cox said he could not speculate why Sutent fell short in the study, but said the disappointing results are not necessarily an indication of how Sutent will fare in ongoing studies.