AbbVie Inc. encountered a major regulatory setback as the FDA declined its application for ABBV-951, a therapy aimed at treating motor fluctuations in advanced Parkinson's disease patients. This rejection comes amid AbbVie's prediction of a 37% sales decline for its flagship product Humira due to increasing competition. Despite the challenges, AbbVie reported a significant revenue of $15.12 billion last quarter and continues to invest in other promising treatments, including upadacitinib for lupus, as it aims to strengthen its drug pipeline.