Atlanta CytRx Corp. reported on WednesdayPhase II trial results showing that RheothRx incombination with clot busters streptokinase ortissue plasminogen activator (t-PA) reduced therate of myocardial infarction (MI) by 38 percentcompared with thrombolytic and a placebo.The Norcross, Ga., company also said at theAmerican College of Cardiology meeting herethat the drug lowered the risk of a repeat heartattack during hospitalization, providedsignificantly better heart function (ejectionfraction) after heart attack, and caused few sideeffects, except in patients with renal dysfunction.A previous Phase II trial found that RheothRxhad no advantage over coronary angioplasty. ACytRx spokesman added that in that trial,RheothRx was not administered to patients assoon as it was in the thrombolytic trial.The randomized, placebo-controlled Phase IItrials combining RheothRx with thrombolyticswere conducted on 114 patients at 12 clinicalsites in the U.S. Gary Schaer, associateprofessor of medicine and director of the CardiacCatheterization Laboratory at Rush-Presbyterian-St. Luke's Medical Center inChicago, was the principal investigator. Clinicalendpoints of the study were to reduce death,shock and reinfarction. Patients were acceptedinto the study if they had chest pain that hadbeen ongoing for at least 30 minutes, showedsigns of an acute heart attack, and if thetreatment could be administered within six hoursof the onset of symptoms.RheothRx was administered as a 48-hourcontrolled infusion, and patients in both thecontrol and trial groups received aspirin andheparin. The infarction rate was measured with anuclear scan upon admission to the trial andagain after five to seven days.Some patients in the RheothRx groupexperienced an elevated creatinine level, whichwas spontaneously reversible before they left thehospital. Nonetheless, Schaer warned thatpatients with renal dysfunction would have to bewatched closely and their dosage levels carefullymonitored.Schaer said RheothRx (polymer 188) enhancesthe speed of reperfusion and reduces the risk ofreperfusion injury. He said it improves blood flowand reduces blood viscosity, cellular adhesionand blood cell occlusion, with no adverse effectson blood pressure or heart rate.The mortality rate in the trial group was 9percent compared with 11 percent in the placebogroup. Schaer said the trial was too small topermit conclusions about mortality or shock. Nolong-term follow-up of the patients is planned,although Schaer said that by reducing the size ofa heart attack, the benefits of RheothRx could beprolonged.CytRx said Phase III trials will begin soon and beconducted by the company's licensee,Burroughs-Wellcome, at a cost of $30 million.The trial of 9,100 patients will be conducted insome 300 centers in the U.S., Canada, SouthAmerica and Europe. Enrollment is expected totake 18-24 months and follow-up will last from 35days to six months. The Phase III trial willattempt to establish appropriate dosagesthrough five different dosage regimens and aplacebo group.Wellcome said it is also considering usingRheothRx to prevent heart attacks.031794 RheothRx
-- Philippa Maister
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