Just as MedImmune Inc. prepares to launch its FDA-approvedpolyclonal antibody, RespiGam, to prevent respiratory syncytial virus(RSV) in infants, the company is beginning a pivotal clinical study ofa monoclonal antibody against the same infectious disease, whichsends 90,000 youngsters to the hospital each year and kills 4,500 ofthem.

The monoclonal antibody, called MEDI-493, blocks a proteinessential for the virus' infection of cells, said Mark Kaufmann,associate director of strategic planning and investor relations atMedImmune, of Gaithersburg, Md.

Given intramuscularly, MEDI-493 would be a more convenienttreatment than RespiGam, which must be infused intravenously fortwo to four hours. In addition, the humanized monoclonal antibody isconsidered more potent and easier to make than RespiGam, which isderived from limited supplies of donor blood.

Kaufmann, however, said if MEDI-493 is successful, RespiGamlikely will not disappear. The clinical studies supporting RespiGam'sapproval showed the immunoglobulin not only reduced RSV-relatedhospitalizations by 40 percent, but also lowered significantly thenumber of hospital treatments for other infections because of thevariety of antibodies contained in the donor blood.

RSV is a leading cause of pneumonia and other respiratory ailments,such as bronchiolitis, in infants and children. The seasonal virus canbe life-threatening for prematurely born youngsters and children withbronchopulmonary dyplasia (BPD).

RespiGam was approved in January 1996 for prevention of RSV inchildren under 24 months old who have BPD or were bornprematurely. MedImmune, which has a co-promotion agreement inthe U.S. with American Home Products Corp., of Madison, N.J.,currently is launching the drug in preparation for the fall, winter andspring seasonal RSV outbreaks.

MedImmune has a collaboration with Baxter Healthcare Corp., ofDeerfield, Ill., for marketing RespiGam outside North America.

The Phase III placebo-controlled trial of the monoclonal antibody,MEDI-493, has begun at more than 130 medical centers in the U.S.About 1,200 children, both prematurely born infants and youngsterswith BPD, will be enrolled by the end of the year.

The study will attempt to establish MEDI-493's ability to preventhospitalizations related to RSV.

Eight hundred children will receive one injection of the monoclonalantibody per month for five months while the other 400 will get aplacebo shot. Treatments will end in April 1997 and the participantswill be followed for a month.

Results of the Phase III study are expected by the third quarter of1997 and if the drug is effective, the data, along with findings fromearly trials, would be sufficient for submission to the FDA formarketing approval.

In an October 1995 amendment of its RSV collaboration agreementwith American Home Products, MedImmune regained all marketingrights to MEDI-493. AHP will receive royalties on sales ofmonoclonal antibody.

MedImmune's stock (NASDAQ:MEDI) closed Wednesday at$15.125, down $0.125. n

-- Charles Craig

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