Protein Design Labs Inc. stopped enrolling patients in a Phase II trialof its anti-cytomegalovirus (CMV) retinitis antibody after the grouprunning the trial recommended the use of higher doses.

The human antibody, Protovir, was being tested as a supplement toprimary therapy in AIDS patients being treated for their first episodesof CMV retinitis. About half of the 167 patients planned for the studyhad been enrolled when the AIDS Clinical Trials Group (ACTG)protocol team temporarily closed patient enrollment.

Protein Design Labs (PDL) corporate communications director PeterDworkin said the company intends to continue the study onceregulatory approvals to increase the doses are granted.

Last month the same product failed to perform better than placebo ina Phase II/III trial in AIDS patients with CMV retinitis. That studyincluded patients who had failed previous therapies as well as thosewith newly diagnosed CMV. The stock lost $7.63 that day to close at$15.50. (See BioWorld Today, Aug. 16, 1996, p. 1.)

The Mountain View, Calif., company's stock (NASDAQ:PDLI) fell50 cents Thursday, following release of the news late Wednesday, toclose at $18.88.

The suspended study included drug arms of 15 mg and 60 mg _dosed once every two weeks _ in combination with approvedantiviral agents, as well as an arm consisting of the approved agentonly. The 60 mg dose was the one that failed to beat placebo in theother study.

Dworkin said earlier studies had included doses as high as 300 mg,but company officials thought 60 mg would be adequate. However,he said, more drug might be needed for treating CMV retinitisbecause of the difficulty in getting drug to the eye.

The antibody also is being studied in a Phase II trial to prevent CMVinfections in patients undergoing bone marrow transplantation.Nearly all patients for that study have been enrolled. A data safetymonitoring board last week determined there were no drug-relatedadverse events in the trial.

The Phase II AIDS-related CMV retinitis study is being run byACTG, which is supported by the National Institute of Allergy andInfectious Diseases, a component of the National Institutes of Healthin Bethesda, Md. The ACTG proposed those patients alreadyenrolled in the study have the option to continue under the currentprotocol or withdraw from the study. n

-- Jim Shrine

(c) 1997 American Health Consultants. All rights reserved.