Nabi Biopharmaceuticals signed an agreement to take over the North American development and commercialization rights to a Fresenius Biotech GmbH organ transplantation compound.

The company gains exclusive sales and distribution rights in the U.S. and Canada for up to 15 years following a U.S. launch, and will pay Fresenius, a subsidiary of Bad Homburg, Germany-based Fresenius AG, milestone payments of $1 million during development and $4 million upon FDA approval of ATG-Fresenius S, which is used to prevent and treat acute rejection following organ transplantation. In exchange for a royalty, Fresenius will manufacture and supply the product from its European facility.

The licensed product complements Boca Raton, Fla.-based Nabi's approved drug Nabi-HB, which is indicated to prevent hepatitis B infection following accidental exposure to the virus, but also is used to prevent HBV re-infection in HBV-positive liver transplant patients.

"I think basically it bolsters our franchise in transplantation," said Thomas Rathjen, Nabi's vice president of investor relations, "and it's closely aligned with our existing expertise and development infrastructure."

The company already has a 50-person sales force that promotes Nabi-HB, which was approved in March 1999. It had sales of $39.2 million in 2005, down from the $40.2 million it brought in the previous year, due to lower HBV liver transplant activity. Rathjen said the same sales force would be able to promote ATG-Fresenius S.

"It dovetails nicely into our capabilities," he said.

ATG-Fresenius S, a polyclonal antibody preparation used for T-lymphocyte suppression, is marketed by Fresenius in more than 60 countries worldwide and has demonstrated its ability to significantly reduce transplant failure and substantially improve survival rates.

The North American rights were partnered with Enzon Pharmaceuticals Inc., of Bridgewater, N.J., in June 2003, but Enzon returned the rights in January to Fresenius so it could focus on cancer and adjacent therapeutic areas.

"From what we understand, they decided to go a different direction with their pipeline," Rathjen told BioWorld Today.

In January 2005, the FDA granted fast-track status of ATG-Fresenius S in lung transplantation, and Enzon dosed the first patient in a Phase III trial. Nabi will take over responsibility for the ongoing study, a randomized, double-blind, placebo-controlled trial being conducted in the U.S. and Europe. The primary endpoint is the occurrence of acute transplant rejection, graft loss or death within six months post-transplant.

Nabi also may undertake additional studies to expand the indications into bone marrow transplantation and other areas. If all goes well, the company could be prepared to file a biologics license application for ATG-Fresenius S in early 2009.

More than 26,000 solid-organ transplants were conducted in the U.S. in 2004, and the numbers are increasing by 4 percent annually. Greater than 60 percent of the procedures involve the replacement of a kidney, while 23 percent are for liver transplants.

Studies in Europe have shown that ATG-Fresenius S targets the cells responsible for organ rejection better than other products. It works by selective suppression of activated cells responsible for the rejection of transplanted organs.

"This is a product that is well tolerated. There are fewer side effects with this product, so in that regard, we think it will be well-received in the U.S." Rathjen said. "Certainly, it has shown good efficacy in over 150,000 transplant patients in 60 countries."

Nabi expects to start a Phase II proof-of-concept trial for a complementary transplantation product, Civacir, in the second half of this year. The product is designed to prevent re-infection with the hepatitis C virus in hepatitis C liver transplant patients.

The company also is developing StaphVAX and Altastaph for Staphylococcus aureus-caused infections. Poor clinical data last year left their fate in question, but further analyses of the data gave the company a reason to continue development of the Gram-positive programs. (See BioWorld Today, March 23, 2006.)

In addition to Nabi-HB, the company markets PhosLo, a phosphate binder indicated to control hyperphosphatemia in patients with end-stage renal disease, and Aloprim, an injectable approved to manage patients with leukemia, lymphoma and solid-tumor malignancies who are receiving cancer therapy that causes elevations of serum and urinary uric acid levels and who cannot tolerate oral therapy.

Nabi's stock (NASDAQ:NABI) rose 9 cents Tuesday to close at $5.55.