Why Is Agios Pharmaceuticals Stock Sinking Today?

Core Viewpoint - Agios Pharmaceuticals Inc. experienced a significant stock decline following the release of Phase 3 trial results for mitapivat in treating sickle cell disease, despite meeting its primary endpoint of hemoglobin response [1][10]. Trial Results - The RISE UP Phase 3 trial met its primary endpoint, showing a statistically significant improvement in hemoglobin response with 40.6% of patients in the mitapivat arm achieving this response compared to 2.9% in the placebo arm [2][3]. - Mitapivat also demonstrated a reduction in the annualized rate of sickle cell pain crises (SCPCs), with rates of 2.62 in the mitapivat arm versus 3.05 in the placebo arm, although this did not achieve statistical significance [3][4]. - Statistically significant improvements were observed in two key secondary endpoints: average change in hemoglobin concentration and levels of indirect bilirubin from baseline [4][6]. Safety and Efficacy - The safety profile of mitapivat in this trial was consistent with previous studies, with an average change in hemoglobin concentration of 7.69 g/L in the mitapivat arm compared to 0.26 g/L in the placebo arm, indicating a statistically significant improvement [6]. - The average change in indirect bilirubin was -16.03 µmol/L in the mitapivat arm versus 0.88 µmol/L in the placebo arm, also showing a statistically significant improvement [7]. Future Plans - Agios plans to submit a marketing application for mitapivat in the U.S. for sickle cell disease after a pre-supplemental New Drug Application meeting with the FDA in early 2026 [8]. - The company is also focused on other commercial and pipeline milestones, including the potential U.S. approval of Pyrukynd (mitapivat) for thalassemia, expected in December 2025 [8][9]. Stock Performance - Following the trial results, Agios Pharmaceuticals' stock fell by 49.00%, trading at $23.20, near its 52-week low of $23.41 [10].