UPDATE 3-Medicare seeks evidence to support anemia change

(Adds Amgen comment)

By Kim Dixon and Toni Clarke

WASHINGTON/BOSTON, Sept 24 (Reuters) - The U.S. Medicare agency said on Monday that, unless it receives new evidence, it will not reverse a decision to cut reimbursement for best- selling anemia drugs, such as Amgen Inc's (AMGN.O: Quote, Profile, Research, Stock Buzz) Aranesp.

The U.S. Centers for Medicare and Medicaid Services (CMS), the biggest purchaser of prescription drugs, made its position clear in a letter sent to physicians and others who sought to persuade the agency to reverse its stance.

CMS gave advocates 30 days to deliver proof to support a different conclusion than reached by the agency in its review of more than 800 publications and 2,600 comment letters.

The decision by the government earlier this year to cut reimbursement of a class of drugs known as erythropoiesis- stimulating agents, or ESAs, in some cancer patients was prompted by studies suggesting the drugs, which include Johnson & Johnson's (JNJ.N: Quote, Profile, Research, Stock Buzz) Procrit, are overused and linked to an increased risk of stroke and heart attack.

Several Wall Street analysts said Medicare set a high bar for making any changes to its ruling.

"CMS is digging in its heels, making any (coverage) change unlikely," Jefferies & Co analyst Adam Walsh wrote in an investor note.

The drugs are given to boost oxygen-carrying hemoglobin in the blood to combat anemia and avoid blood transfusions. Doctors and cancer centers buy the drugs from manufacturers and get reimbursed for patients on Medicare, the federal health plan for the nation's 43 million elderly and disabled.