Cassava Sciences Inc. /zigman2/quotes/204212356/composite SAVA -5.17% responded Wednesday to allegations posted overnight regarding the "accuracy and integrity" of trial data for its treatment of Alzheimer's disease, saying it believed the claims are "false and misleading." Cassava's stock had rallied 1.9% on Tuesday, and 16.4% over the past three days, with the company saying early Tuesday that it reached agreement with the Food and Drug Administration under a Special Protocol Assessment (SPA) for its Phase 3 studies of oral simufilam for the treatment of Alzheimer's patients. The stock then tumbled after the bell -- it was down 17.8% in Wednesday's premarket -- after a "statement of concern" was posted requesting the FDA halt the current clinical studies of simufilam, disputing the validity of clinical biomarker data, the integrity of western blot analyses and the integrity of analyses involving human brain tissue. "As a science company, we champion facts that can be evaluated and verified," said Chief Executive Remi Barbier. "This helps people make informed choices. It is important for stakeholders to separate fact from fiction, which is why we wish to address allegations head-on." Cassava responded to the "fiction" regarding biomarker data with the "fact" that data from Alzheimer's patients were generated by an independent company, Quanterix Corp., and said western blot analysis is "foundational," and a standard lab technique used to detect a protein of interest. The stock has rocketed 1,627.7% year to date through Tuesday, while the S&P 500 /zigman2/quotes/210599714/realtime SPX -0.84% has gained 19.4%.