What's the riskiest big biotech stock on the market? According to market research firm EvaluatePharma, it's Celgene (NASDAQ: CELG).Many investors have been very bearish about Celgene for months. The company's once-promising Crohn's disease drug GED-0301 flopped miserably in a late-stage clinical study in October 2017. Celgene thoroughly embarrassed itself, with the FDA refusing to review the regulatory submission of ozanimod in treating multiple sclerosis (MS).