By Lisa Seachrist

Washington Editor

WASHINGTON - Chiron Corp. reported positive Phase II clinical trial results for its conjugated Meningococcus C (MenC) vaccine.

In a study published in the Nov. 18 Journal of the American Medical Association, the company's Canadian collaborators reported the conjugated MenC vaccine provided a lasting immune response compared to the currently available polysaccharide vaccine, which does not offer long-lasting immunity.

Emeryville, Calif.-based Chiron is testing the vaccine in a Phase III study in the U.K., which is expected to finish by 2000.

"Currently, our development focus is for the U.K. and Europe," said Chiron spokeswoman Gabrielle Friedly.

Meningococcus meningitis is a serious bacterial disease that strikes otherwise healthy infants, children and adolescents. Caused by several different strains of Neisseria meningitidis, it is the only form of bacterial meningitis that leads to epidemics. "Meningococcal meningitis starts with a fever and a rash, with rapid onset of sepsis," said Lisa Danzig, associate director of clinical research at Chiron. "It's a disease with a very high mortality rate and serious morbidity."

The disease has a 10 percent mortality rate in Europe and North America, and an even higher rate in developing countries. When not fatal, the infection can result in serious complications requiring the amputation of limbs.

In North America and Europe, serogroup C represents about 45 percent of all diagnosed cases of meningococcal meningitis. Chiron's strategy linked the polysaccharide antigen of MenC to a diphtheria antigen to form a conjugated vaccine.

"Conjugate vaccines are supposed to induce immunologic memory," Danzig said.

The Canadian Phase II study tested more than 200 toddlers who were given two injections, two months apart, of either Chiron's MenC vaccine or a meningococcal polysaccharide vaccine. The control group received a hepatitis B vaccine. All participants were challenged with a dose of the polysaccharide vaccine to test their ability to produce antibodies in response to the antigen one year after the second injection.

Initial Approval Push In U.K., Europe

Chiron's vaccine produced antibody levels four times higher than the polysaccharide vaccine after the first injection, and 10 times higher after the second injection, with no serious side effects. That performance difference persisted over time, as measured at the 12-month follow-up.

The company has conducted Phase II studies of the MenC conjugated vaccine in the U.S., the U.K. and the Netherlands, as well as in Canada. However, the initial push for approval of the vaccine will be in the U.K. and Europe. The U.K. has proposed mandating universal immunization of infants, and wants to have all individuals under age 21 inoculated.

In other Chiron news, the European Commission has cleared the way for Bayer's Business Group Diagnostics, headquartered in Tarrytown, N.Y., to acquire Chiron Diagnostics for $1.1 billion. The U.S. Federal Trade Commission has allowed the review period required under the Hart-Scott-Rodino Act to expire, without requesting additional information to permit the acquisition. (See BioWorld Today, Sept. 18, 1998, p. 1.)

With European and U.S. regulatory hurdles overcome, the companies expect the deal to be completed before the end of the year.

Chiron's stock (NASDAQ:CHIR) closed at $23.125, up $0.062. n