BioMarin's ($BMRN) drug for a rare enzyme deficiency resulted in a "modest" improvement for patients, according to an FDA staff review, possibly lowering expectations for the company's Tuesday meeting with an agency advisory panel. The disease, called Morquio A, causes skeletal malformation and restricts mobility, and BioMarin's Vimizim treatment helped patients walk 22.5 meters farther than with a placebo but had no significant effect in a three-minute stair climb test, the FDA said. The agency is expected to decide on the drug by the end of February. Review (PDF)