SMITHKLINE LEUKOTRIENE ANTAGONIST CLINICAL HOLD

SMITHKLINE LEUKOTRIENE ANTAGONIST CLINICAL HOLD on Phase III studies in asthma is the subject of ongoing meetings between the company and FDA to resolve the issue of bronchospastic responses in some patients. SmithKline is working on a new formulation of the aerosol compound, SK-104353, which would not include an excipient, citrate EDTA, that apparently caused the adverse reactions in one of the company's studies. The two patients who participated in the trial were affected. The clinical hold was imposed approximately two months ago. The study was sponsored by SmithKline and conducted by an outside investigator at one U.S. center. The company has studied the leukotriene antagonist in a total of 110 patients, including the two who suffered the bronchospastic reaction, in 13 centers in the U.S. and in Europe. SK-104353 is SmithKline's lead compound in the area of leukotriene research. The agent entered clinicals in 1987. Smith Kline & French Labs R&D President George Poste discussed the leukotriene antagonist at a Feb. 2 analysts meeting in New York City. He reported that although trials are currently on hold, during 1988 the firm was able to demonstrate efficacy in asthmatics, both in prophylactic and therapeutic settings. "We made good progress throughout 1988 ]on SK-104353[ and therefore it is paradoxical to announce to you that this agent is currently on clinical hold," Poste said. However, he maintained that "citrate EDTA is an excipient which has been shown to elicit bronchospastic responses with a wide variety of other drugs." Poste also stated that since the bronchospastic reactions were not seen with any of the other formulations used, "we're quite confident that the clinical hold will be lifted shortly." SmithKline plans to take an orally active analog of the compound into the clinic in 1989. The firm is also looking at additional indications for inflammatory bowel disease and endotoxic shock. Other companies with leukotriene antagonists in clinicals include Schering-Plough, with an oral leukotriene antagonist, SCH 37224, in Phase II study for allergic rhinitis. The company also plans a Phase II pilot study for asthma. Rorer's RG-7152 is in Phase I testing for allergic rhinitis and Merck has a leukotriene in Phase II.