MERCK AND MEDIMMUNE REVIEWING ANTI-HIV MAb COLLABORATION

MERCK AND MEDIMMUNE REVIEWING ANTI-HIV MAb COLLABORATION following "unexpected research results" with MedImmune's lead anti-HIV monoclonal antibody MEDI 488, MedImmune announced Jan. 4. In response to the unexpected results, the two companies have initiated "a series of new laboratory experiments and an overall review of the program," MedImmune said. "MedImmune and Merck expect to complete the program review within the next two months and then to decide whether or not to continue the program." "Due to the genetic variability of the HIV virus and the complexity of the infection in humans, MedImmune continues to believe any expectations for MEDI 488 would remain highly speculative, even if the new series of laboratory experiments warrant continuation of the research program," the company cautioned. Merck entered into a collaboration with MedImmune in October 1991 to develop MAbs to treat AIDS. The deal called for Merck to pay MedImmune up to $13 mil. in research funding and milestone payments over three years ("The Pink Sheet" Oct. 28, 1991, T&G-9). Merck signed up with MedImmune after terminating a similar collaboration with Repligen; at the time, Merck indicated that it believed MedImmune's MAbs may be active against more strains of the AIDS virus. Merck also is collaborating with MedImmune on AIDS vaccine research under a November 1990 deal. In a separate Jan. 4 announcement, MedImmune said it has filed a PLA for its Respivir polyclonal antibody for prevention of respiratory syncytial virus (RSV) in children. MedImmune estimates that there are more than 90,000 hospitalizations and 4,500 deaths from RSV in the U.S. annually. "Children with pre-existing conditions, including lung or heart disease, prematurity or immunosuppression, are at significantly increased risk for severe disease and death from RSV," MedImmune said. "No product is currently licensed for prevention of RSV infection in the U.S." Phase II/III clinical trials of Respivir (formerly Hypermune- RSV) began in 1989 at five centers in the U.S. The trials enrolled about 250 patients and concluded in April. Results will be presented at the Society for Pediatric Research meeting in May 1993, MedImmune said. Respivir is delivered by I.V. infusion once per month during the five-month RSV season. "Initial infusions are likely to occur in hospital clinics," MedImmune said, "with subsequent infusions either in hospital clinics or through home infusion care." MedImmune added that two three-year trials of Respivir as a treatment for RSV are nearing completion. "If successful, these trials could provide the basis for an application to be filed with the FDA late in 1993 for use of Respivir to treat RSV pneumonia and bronchiolitis," MedImmune said. "Respivir, if and when the PLA is approved by the FDA, has the potential to generate significant product sales for MedImmune," according to the company. During a September appearance at a Bear Stearns securities analysts meeting in New York City, the company estimated the RSV market at $400 mil. per year in the U.S. "We also expect that Respivir could reduce the overall health care cost associated with RSV disease by among other things reducing the incidence of hospitalization and intensive care unit admission," MedImmune said. Respivir will be marketed in the U.S. by MedImmune's own sales force, currently numbering 14 reps. The Gaithersburg, Md. company is seeking a partner to launch the product in foreign markets. Respivir is licensed from the Massachusetts Health Research Institute. MedImmune's detail force is launching its first product, the cytomegalovirus treatment CytoGam, the company said Jan. 5. CytoGam has been marketed in the U.S. by Connaught since November 1991 for prevention of CMV in kidney transplant patients. In October, Cytogen announced that it was reacquiring rights to the product in the U.S. for $4.5 mil. plus royalties ("The Pink Sheet" Nov. 2, p. 19). "An application for an expanded indication for prevention of CMV disease in all solid organ transplants was filed in June 1992," MedImmune said. The sales organization for CytoGam will provide "a platform for launching Respivir," MedImmune added.