SCHERING-PLOUGH’s INTRON A FOR CHRONIC HEPATITIS B APPROVED JULY 13
SCHERING-PLOUGH's INTRON A FOR CHRONIC HEPATITIS B APPROVED JULY 13 for use in adults -- 18 years or older -- with compensated liver disease and HBV replication. The approval follows by almost eight months a review of three studies involving more than 200 patients by FDA's Biological Response Modifiers Advisory Committee. At its Nov. 25 meeting, the panel unanimously recommended approval of the recombinant alfa-2b interferon product ("The Pink Sheet" Dec. 2, 1991, p. 5). Intron A is currently marketed for the treatment of hepatitis C, hairy cell leukemia, AIDS-related Kaposi's sarcoma and genital warts. In two four-month studies submitted by Schering as part of its supplemental PLA, patients with chronic hepatitis B received subcutaneous injections of either 5 mil. units daily or 10 mil. units three times a week. Approved labeling notes that in each of two randomized, controlled studies, 42% and 54% of Intron A- treated patients, respectively, had a virologic response, defined as a reduction of serum markers of HBV replication. In a third study without a concurrent control group, patients exhibited a similar response. Investigators also measured patients' levels of the liver enzyme alanine aminotransferase to determine the extent of liver damage. Intron A showed positive results in preventing a relapse of the liver infection. None of the responding patients in the studies relapsed during a follow-up period of two to six months. Of the 101 patients treated with 5 mil units, 98% had some type of adverse reaction as did 90% of the 78 patients treated with 10 mil. units. Severe adverse reactions were reported in 21%- 44% of the patients studied. "The severe adverse reactions reported most frequently were the flu-like symptoms of fever (28%), fatigue (15%), headache (5%), myalgia (4%), and other severe flu-like symptoms which occurred in 1% to 3% of patients," labeling notes. However, most patients experienced mild to moderate reactions such as rashes, which were manageable and reversible following the completion of therapy. Five percent of patients discontinued treatment due to adverse reactions. Intron A for hepatitis B is contraindicated in "patients with decompensated liver disease, autoimmune hepatitis or a history of autoimmune disease and patients who are immuno-suppressed transplant recipients," labeling states. "There are reports of worsening liver disease, including jaundice, hepatic encephalopathy, hepatic failure and death following Intron A therapy in such patients." In addition, the labeling also notes that "chronic hepatitis B patients with evidence of decreasing hepatic synthetic function, such as decreasing albumin levels or prolongation of prothrombin time, may be at increased risk of clinical decompensation with a flare of amino-transferases during Intron A treatment." For these patients, potential risks must be evaluated against the potential benefits of treatment. According to the Centers for Disease Control, there are 750,000 to 1 mil. HBV carriers in the U.S., of whom one in four will develop chronic active hepatitis B. The liver disease can progress to cirrhosis and hepatic cell carcinoma, an often fatal liver cancer. "Every year, some 300,000 Americans become infected with the virus that causes hepatitis B," Commissioner Kessler remarked in a July 13 press release. "It is fortunate that there is now a treatment that may halt the progression of the disease." Hepatitis B "is a serious public health problem that is too often overlooked," HHS Secretary Sullivan said in the release, adding that Intron A therapy "will help save lives and reduce the suffering that accompanies this disease." While Intron A is the first treatment to be approved for hepatitis B, two recombinantly-produced vaccines are available in the U.S. -- SmithKline Beecham's Engerix B and Merck's Recombivax HB. Both products have benefited from greater awareness of the risk of HBV infection, and an Occupational Safety and Health Administration requirement implemented March 6 that hospitals and other employers make the vaccines available to workers who are at risk on the job.
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