CytRx Corp. (CYTR) said it has stopped a Phase II trial of RheothRx in heart attack patients ineligible to receive thrombolytics after enrolling 200 of 250 planned patients because of data showing an unusual incidence of acute renal dysfunction at higher doses.

RheothRX is a polymer that coats blood cells so they can slide past clots. Earlier studies have shown efficacy with lower doses, CYTR noted. "Typically you'll push the dose as high as you can until