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) 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) 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.

CMS said in July it would only reimburse for cancer patients undergoing chemotherapy whose hemoglobin levels fell below 10 grams per deciliter of a patient's blood.

Doctor groups, including the American Society for Clinical Oncology, had asked Medicare to reconsider the cancer decision, arguing they interfere with the practice of medicine and jeopardize patient care.

But in its letter, the agency wanted specific questions answered -- among others, proof that patients undergoing chemotherapy require hemoglobin levels above 10 grams per deciliter. And it asked for evidence that use of ESA therapy is superior to blood transfusion for maintaining that 10 gram per deciliter level.

Amgen said in a statement that the CMS coverage decision has resulted in a different standard of care for Medicare beneficiaries versus privately insured patients -- who the company said are still being treated according to current clinical guidelines.

"This government policy undermines clinical judgment, effectively removes physicians' ability to make decisions, and is unreasonable and impractical," Amgen said.

Amgen added that multiple parties involved in the debate have presented CMS with arguments showing the agency "materially misinterpreted existing evidence." Consequently, Amgen said CMS "has already received answers to a number of the questions" posed in its letter on Monday.

J&J was not available for comment.