Early Tuesday morning, Rigel Pharmaceuticals (NASDAQ: RIGL) and its now-ex-partner, AstraZeneca (NYSE: AZN), reported late-stage clinical trial results for the experimental rheumatoid arthritis drug Fostamatinib. In the following video, health-care analyst Max Macaluso discusses why Rigel dropped 18% after the news was released and the risks that lie ahead for Rigel Pharmaceuticals.