In this video from The Motley Fool's "Ask a Fool" series, Fool health-care analyst Max Macaluso takes a question from a Fool reader, who asks, "What is your Foolish opinion of Horizon Pharma (NASDAQ:HZNP)?" This commercial-stage biotech company has seen its shares blow through the roof over the past year, up a staggering 475% over the past 12 months. What has driven this white-hot run, and is there still time for investors to get in? Max breaks the company's success down to three key factors that investors need to be aware of, and isolates one major risk shareholders could face from here.