Medarex Inc., of Princeton, N.J., named Irwin Lerner interim president and CEO.

MediciNova Inc., of San Diego, appointed Shintaro Asako chief financial officer.

MedImmune Inc., of Gaithersburg, Md., appointed Bernardus Machielse executive vice president of operations; Frank Malinoski senior vice president of medical affairs; Christine Dingivan senior vice president of clinical development and operations; John Lewis vice president of global engineering capital products; Herren Wu vice president of antibody discovery and protein engineering; and Alan Taggart vice president of government project management.

National Stem Cell Holding Inc., of New York, named Michael J. Shamblott chief scientific adviser.

New River Pharmaceuticals Inc., of Radford, Va., named Garen Manvelian chief medical officer.

Orexigen Therapeutics Inc., of San Diego, named Eduardo Dunayevich chief medical officer, Ronald Landbloom vice president of medical and regulatory affairs, Frank Bymaster vice president of neurobiology, James Lancaster vice president of commercialization and Shannon Lee Mount director of clinical operations.

Osteologix Inc., of San Francisco, appointed Jeremy Curnock Cook to its board.

Pharmacopeia, of Princeton, N.J., appointed Rene Belder vice president, clinical and regulatory affairs.

Pharmaxis Ltd., of Sydney, Australia, appointed John Villiger to its board.

Prolacta Bioscience, of Monrovia, Calif., named Scott Elster CEO.