In separate announcements late Tuesday, Repligen Corp. said itis dissolving its collaboration with Merck & Co. Inc. to developan anti-infective monoclonal antibody against AIDS, and Mercksaid it has reached a $13 million agreement to develop similartherapeutics with MedImmune Inc.
Repligen will reacquire from Merck its rights to themonoclonals and will continue the program on its own from itscash reserves. Repligen of Cambridge, Mass., said details of thereacquisition have not been finalized.
Just last Friday, Repligen and Merck presented promisingpreclinical data obtained from a chimpanzee injected withtheir compound, a monoclonal antibody to the V3 loop of thevirus.
Repligen shares (NASDAQ:RGEN) have soared based on thereport, closing Tuesday at $29, up $5.25 for the day and up$11.63 in the three trading sessions since the results wereannounced. Tuesday's announcements came after the markethad closed.
MedImmune stock (NASDAQ:MEDI) closed up 75 cents at $35.13.In May, it completed its initial public offering at $9.25.
In its new collaboration, Merck is buying all rights to anyproduct that emerges from MedImmune's immunotherapyapproach to AIDS, said Wayne Hockmeyer, MedImmune presidentand chief executive officer. The Gaithersburg, Md., companywill retain worldwide rights to co-promote any productsresulting from the program.
Under the agreement in principle, Merck of Rahway, N.J., willprovide MedImmune with $13 million over the next three years,beginning in the last quarter of 1991, to continue research intoanti-HIV monoclonals. In addition, Merck "will fund all thework needed to bring to market" a monoclonal that has alreadyshown promise in vitro, Hockmeyer told BioWorld.
In test tubes, the monoclonal to a short, highly conservedregion of the V3 loop has neutralized all of the divergentlaboratory strains of the AIDS virus that were tested. Thesetests were conducted at Merck, Merck spokesman John Doorleysaid, but he did not know how many strains were challenged.
The V3 loop of the HIV coat protein gp120 has been identifiedas a highly conserved region among AIDS viral strains. Yet todate, antibodies to it have not been able to neutralize morethan a few strains.
In the Repligen studies, a chimp injected with infectious dosesof HIV-1 and then infused with the monoclonal antibody to theV3 loop has remained free of HIV infection since the test wasbegun in March.
Merck and Repligen will continue to work on an AIDS vaccineunder a separate agreement.
-- Roberta Friedman, Ph.D. Special to BioWorld
(c) 1997 American Health Consultants. All rights reserved.