Cytokinetics tumbles as FDA delays heart drug review by 3 months

Shares of drug developer Cytokinetics CYTK.O fall 15% to $36.52

Late on Thursday, co said that the US FDA has extended the review date for its marketing application of heart disease drug aficamten to Dec. 26

*Stock set for biggest single-day percentage drop in nearly a year, if losses hold

Previous action date was Sept. 26

Extension is due to the FDA needing more time to review the co's proposed Risk Evaluation and Mitigation Strategy (REMS) for the drug - CYTK

REMS is a safety program required by the FDA to ensure a drug's benefits outweigh its risks by managing serious safety concerns

No additional clinical data or studies are required - CYTK

Co is seeking approval of the drug to treat obstructive hypertrophic cardiomyopathy, in which heart muscles become stiff and can cause cardiac arrest

UBS analyst Ashwani Verma said that the FDA extension is a "concern"

*Including session's move, CYTK down 22.4% YTD vs. ~1% decline in the NASDAQ biotechnology index .NBI