BIOGEN’s HIRULOG PHASE II DATA SHOW ADVANTAGE OVER HEPARIN

BIOGEN's HIRULOG PHASE II DATA SHOW ADVANTAGE OVER HEPARIN in reducing bleeding complications and coronary thrombus in patients with unstable angina, according to a study presented Nov. 17 at the American Heart Association's 65th Scientific Sessions. Hirulog, a synthetic leech protein derivative, is a direct- thrombin inhibitor. An open-label, Phase II study of 20 patients with unstable angina was presented by G. Sharma, West Roxbury V-A Medical Center. Hirulog was given as a continous I.V. infusion for five days at 0.2 mg/kg/hour in 20 males. The primary efficacy endpoints were progression to death, transmural myocardial infarction, or intractable angina. Secondary endpoints were coronary thrombus or bleeding complications. Endpoints with Hirulog were compared to a cohort of 51 unstable angina patients treated with heparin. Overall, Hirulog had a lower adverse event rate than heparin (19.3% versus 44.3%), Sharma said. Hirulog had fewer transmural MIs than heparin (0% versus 2%) and fewer cases of intractable angina (5% versus 9.8%). There were no deaths in either group. The direct-thrombin inhibitor had less incidence of coronary thrombus than heparin (14.3% versus 25.5%) and less incidence of bleeding than heparin (0% versus 7%). Sharma concluded that Hirulog may have advantages over heparin in the treatment of unstable angina. In a Nov. 16 press release, Biogen said that it "is currently conducting a Phase III trial of Hirulog for the treatment of unstable angina and expects to begin a Phase III trial for a second indication in early 1993." Biogen said it is not yet sure what the second indication will be. Hirulog's efficacy as an anticoagulant in place of heparin during coronary angioplasty (PTCA) was also the subject of a Nov. 18 presentation at the AHA meeting. Raoul Bonan, Montreal Heart Institute, presented results from a multicenter, dose-escalation study of over 200 patients given Hirulog intravenously as a bolus followed by a four-hour infusion. Four doses of Hirulog produced elevations in median activated clotting time of 268 seconds, 290 seconds, 336 seconds and 375 seconds. Abrupt vessel closure (thrombotic, mechanical or both) occurred in 11% of patients given the lower doses and in 3% of patients receiving the higher doses. Events occuring in the low dose group were: one death, six MIs, one coronary artery bypass grafting and six abrupt vessel closures (AVCs). In the high dose group there were no deaths, one MI, one bypass, and two AVCs. Bleeding complications included one event in the low dose group that required a transfusion, Bonan noted. Summarizing the results, Bonan said that in the low dose group, "the PTCA...success rate was 90%. In the high dose group, the PTCA success rate was 96%." He added that "compared with historical data for heparin [the study] suggests an improved clinical success rate for PTCA supported by high doses of Hirulog." Another Phase II study discussed at the AHA meeting showed that Hirulog is safe and effective in preventing deep vein thrombosis following orthopedic surgery, according to Biogen.