UPDATE 2-US FDA staff sees benefits, risk with Bristol drug

* FDA reviewers see heart, other benefits with belatacept

* Risk of death from infection, complications also cited

* Bristol: drug avoids toxicities; shares down 1.9 percent

* Agency's outside advisory panel to meet March 1 (Adds company comments, share price, background, byline)

By Susan Heavey

WASHINGTON, Feb 25 (Reuters) - Studies of Bristol-Myers Squibb Co's (BMY.N) experimental kidney transplant drug belatacept show improved blood pressure and other benefits in patients, but concerns over the risk of death are still a factor, U.S. regulatory staff said in documents on Thursday.

The company is seeking FDA approval of the injectable biologic drug to prevent organ rejection and maintain kidney function in patients with end-stage renal disease, saying it offers benefits over current therapies.

On Monday, an FDA advisory panel of experts will meet to discuss whether or not to recommend U.S. approval.

The FDA staff said clinical trial results showed improvements in heart risks, kidney function and other factors. But several cases of post-transplantation complication and a rare disorder called progressive multifocal leukoencephalopathy (PML) are also a concern, they said.

"In summary, careful consideration should be given to whether the data regarding the observed benefits associated with the belatacept regimen ... outweigh the risks of higher mortality and excess morbidity," the staff wrote in documents released ahead of Monday's meeting.

Bristol-Myers, in a separate document, said its data showed belatacept avoids toxicities seen with another type of rejection drug known as cyclosporine, with fewer deaths and serious infections. Cyclosporine, a type of calcineurin inhibitor, (CNIs), is sold as Abbott Laboratories Inc's (ABT.N) Gengraf, Novartis AG's (NOVN.VX) Sandimmune and Neoral.

Bristol-Myers' drug showed it worked comparably well to cyclosporine while avoiding toxicities seen with calcineurin inhibitors, it said, adding that other benefits include a reduction in diabetes and improved blood pressure -- "all of which are important health benefits."

"Overall, belatacept was well tolerated and its safety profile was consistent with that of a targeted immunosuppressant," the company wrote.

Roughly 23 million U.S. adults have chronic kidney disease, which can be treated with dialysis or with a donated healthy kidney. In 2006, more than 18,000 U.S. transplants were performed, according the the National Institutes of Health. As of October 2008, nearly 78,000 people awaited transplants.

As in other organ replacement surgeries, kidney transplant patients face the potential that their body will reject the new organ and must take drugs to help prevent that.

At the meeting, FDA's panel of outside advisors will weigh the company's data and the FDA staff's analysis before making its own recommendations. The agency will later make the final approval decision, expected by May 1.

The FDA panel will also discuss a risk monitoring plan known as a Risk Evaluation and Mitigation Strategy, or REMS, according to documents, which were posted to the FDA's website here

Shares of Bristol-Myers were off 1.9 percent at $24.25 in late morning trade on the New York Stock Exchange. (Reporting by Susan Heavey, editing by Gerald E. McCormick)