MILES' GAMIMUNE N RECOMMENDED FOR APPROVAL IN BONE MARROW TRANSPLANTS
MILES' GAMIMUNE N RECOMMENDED FOR APPROVAL IN BONE MARROW TRANSPLANTS for prophylactic use to reduce infections and the incidence of graft-versus-host-disease by FDA's Blood & Blood Products Advisory Committee on March 26. The committee voted unanimously that the intravenous immunoglobulin gamma (IgG) product be approved for the new indication but recommended that it be restricted to use in patients over the age of 20. Summarizing the committee's conclusions, Chairman Merlin Sayers, MD, Puget Sound Blood Center, said: "The data presented by Miles was sufficient to support a new indication for this preparation as a prophylaxis for bone marrow transplantations in patients greater than 20 years of age." Non-voting committee industry representative and Genetics Institute Regulatory Affairs Director Frederick Gates, PhD, noted that while the conclusion to approve was based largely on retrospective subset analysis, at least the results were consistent in showing that patients over the age of 20 benefited from Gamimune N therapy. "Time and time again...the age differential seems to have come up," Gates said. "If it was a random thing,...I would think that you were looking for a difference that really was not there, but because you've seen this differential appear multiple times there must be some significance to it," he maintained. The committee agreed that the data were sufficient to show that Gamimune N prophylactically decreased the incidence of septicemia, interstitial pneumonia and acute GvHD. They did not find the immunoglobulin effective in reducing local infections. In clinical trials, Gamimune N significantly reduced septicemia in all transplant patients. The immunoglobulin also reduced local infections overall but did not statistically significantly reduce the incidence of specific infections such as gram-negative, gram-positive, other bacterial, viral and fungal infections. Although Gamimune N reduced combined interstitial pneumonia, it did not statistically reduce cytomegalovirus or idiopathic interstitial pneumonia. In addition, Gamimune N showed an overall trend in reduction of acute GvHD. Miles' Gamimune N prospective, randomized, controlled study was conducted in 384 patients undergoing bone marrow transplants at the Fred Hutchinson Cancer Center and the Swedish Hospital in Seattle. The results of the study were presented by Miles Clinical Research Director James Pennington, MD. Patients received 500 mg/kg I.V. immunoglobulin or placebo on a weekly basis from seven days prior to bone marrow transplant to three months post-transplant. After 100 days, patients were put on a monthly regimen of Gamimune N through one year and followed for another year. Patients were stratified in the study by age, more than 20 years old and less than 20 years old. The incidence of GvHD in the treatment group, 20 years and older, was 34% compared to 51% in the placebo group. While Gamimune N prophylaxis seemed to prevent complications of BMT, the immunoglobulin did not have an effect on 100-day mortality, even when groups of patients were stratified by age. FDA Medical Reviewer Karen Weiss, MD, noted that "you would expect if there were improvements in all of these types of outcomes that are associated with a high degree of mortality... [that] that would also be reflected with an improvement in mortality." There was a trend toward decreased non-relapse mortality among patients who were 20 years and older and who had received HLA identical transplants. Noting that there are antibiotics and immunosuppressive agents available to treat BMT patients, FDA consultant John Wingard, Emory University, said he was concerned "whether the magnitude of the benefit [of Gamimune N] justifies the costs." Miles estimates that a weekly course of the IgG over three months will cost hospitals about $13,000 per patient. The company calculates that the actual added cost will be closer to $8,000 per patient when reductions in treatment for infections and GvHD are included in the analysis. Gamimune N reduced hospital stays by four to five days, Miles said. Many BMT centers already use immunoglobulin as prophylaxis for infections and GvHD. FDA Division of Hematologic Products Acting Deputy Director Donald Tankersley told the committee that 75% of the 1,434 patients who underwent bone marrow transplants between 1989 and 1992 were receiving some kind of immunoglobulin therapy. During that time, 47 of the 60 U.S. transplant centers used immunoglobulin in 50% or more of transplants. Several IgG products like Gamimune are currently marketed for primary immune deficiencies and idiopathic thrombocytopenic purpura, including Baxter's Gammagard, Sandoz' Sandoglobulin, Alpha Therapeutic's Venoglobulin-S, and Polygam from the American Red Cross. During the open public hearing portion of the meeting, Herbert Kaiser, MD, Thomas Hazen Thorne Bone Marrow Transplant Center, told the committee that Alpha Therapeutic is conducting a 525- patient trial comparing three doses of Venoglobulin-S in allogeneic bone marrow transplant patients. Enrollment in the trial is expected to be completed by year-end. Swiss Red Cross Director Johann Burkhardt appealed to the agency to grant the BMT indication to all IgG products. "As the manufacturer of Sandoglobulin we propose that the indication of prophylaxis in bone marrow transplantations be a generic rather than an indication for a particular intravenous product," Burkhardt said.
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