Shares of Human Genome Sciences ( HGSI) rose in premarket trading after the company said it was cleared by the FDA to begin testing its ABthrax anthrax treatment on humans. Recently, shares were up 4.4%, or 56 cents, to $13.20, according to Instinet. The Rockville, Md.-based company said the clinical trial will be a phase I, placebo-controlled, dose-escalation test to evaluate the safety, tolerability and pharmacology, but not efficacy, of ABthrax on healthy adults. ABthrax will be dispensed intramuscularly and intravenously. ABthrax blocks the binding of protective antigen to cell surfaces and prevents the anthrax toxins from entering and killing cells, according to Human Genome Sciences. The company said the treatment has already been shown to be effective in animals in preclinical trials with a single dose. The company said that with proper funding, ABthrax could be available for emergency use as early as the end of 2004.