SCHERING INTRON A PLAs FOR HEPATITIS B AND C
SCHERING INTRON A PLAs FOR HEPATITIS B AND C have been filed in the last four months, Robert Kammer, MD, Schering-Plough's director of anti-infectives research, announced at a Prudential-Bache seminar Oct. 11. Schering's product license application for its alfa-2b biosynthetic interferon for hepatitis B was filed in September. The PLA for hepatitis C (non-A, non-B) was submitted in June. The hepatitis B submission includes data on 236 patients administered five million units of Intron A daily for four months. The study found Intron A "to be effective in eradicating the markers of viral replication and reducing hepatic inflammation in 30-50% of patients," Kammer reported. Complete study results will be made public at a meeting of the American Association for the Study of Liver Diseases later this month in Chicago. Schering is conducting ongoing studies in hepatitis B "primarily in patients who have less well compensated liver disease than those that were originally enrolled in the core studies," Kammer noted. In a study of 335 patients diagnosed with hepatitis C, Kammer said Schering researchers found that "53-71% of treated patients had normalization or a greater than 50% reduction in their ALT level as well as improvement in inflammatory liver disease as measured by post-treatment liver biopsy results." The dose was three million units three times a week for six months. The hepatitis C study, done in collaboration with Chiron, found that 86% of patients in the clinicals tested positive for the hepatitis C marker using Chiron's new diagnostic, Kammer noted. FDA and Schering have discussed an expedited review of the hepatitis C PLA; however, he added, "we'll see." New studies are being conducted in dose escalation and maintenance for hepatitis C. "It was clear to us" from the study results, Kammer said, "that there was a dose response, and it also was apparent that significant numbers of patients treated with interferon that respond to treatment completely will relapse when treatment is withdrawn." Schering's follow-up studies are looking at whether an increased dose "will get a higher response rate, and if altered maintenance and treatment regimens will result in a more durable response," Kammer said. In Schering's antibiotic and antifungal R&D activities, Kammer reported that Phase III studies of the third-generation oral cephalosporin ceftibuten (SCH-39720) are "in progress" and that a number of indications are in AIDS clinicals for the systemic anti-fungal SCH-39304. Ceftibuten, licensed by Schering from Shionogi, Japan, is an oral once-a-day suspension cephalosporin that appears similar to Lederle's Suprax (see related T&G). Phase III studies have involved 1,500 patients to date, and Phase II trials were completed in 540 patients with lower respiratory tract infections. The antibiotic also is being studied for urinary tract infections and otitis media. The antibiotic is "highly resistant to hydrolysis by beta lactamase and active against gram negative" infections, Kammer said. Schering is looking at ceftibuten as a possible "step-down treatment" -- like quinolones -- after parenteral drug therapy in order to lessen hospital time, he noted. Kammer described SCH-39304 as Schering's "other major 1989 project" because of the drug's broad application in HIV-related opportunistic and resistant fungal infections. The drug has been assigned high priority status by the AIDS Clinical Drug Development Committee at the National Institutes of Health. SCH-39304, licensed from Sumitomo, has an 80-hour half-life, allowing for possible dosing schedules of as little as once for urinary candidiasis and 600 mg once-weekly for oropharyngeal candidiasis, cryptococcal meningitis and AIDS antifungal prophylaxis in neutropenic patients. Schering has an oral form of the drug in testing now and will have an I.V. form "ready by year end," Kammer said. A Phase II study of the drug in the acute phase of cryptococcal meningitis in AIDS patients has been underway for six months, and the company is "on the bridge to Phase III," Kammer said. Maintenance studies will begin in February, according to Kammer. Among other possible indications for SCH-39304, Schering is also looking at the product as a "preventive" treatment for aspergillosis, he noted.
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