(Adds background on tozadenant, shares)
Nov 20 (Reuters) - Acorda Therapeutics Inc said on Monday it would stop developing its Parkinson's disease drug, less than a week after the company reported deaths in key studies testing the treatment.
The company's shares fell 8.7 percent in premarket trading.
The drugmaker last week reported five deaths in trials for the drug, tozadenant, and said it would stop enrolling patients in two long-term safety trials after it found seven cases of sepsis in mid- and late-stage trials.
Four of the seven sepsis cases were associated with agranulocytosis - the absence of white blood cells.
The drugmaker had said last week it would increase blood cell count monitoring in patients in an ongoing late-stage trial to weekly.
Acorda on Monday said it was not confident that weekly white blood cell count screening would be sufficient to ensure patient safety.
The company had been pinning its hopes on the success of tozadenant, as it battled with the loss of exclusivity on its flagship multiple sclerosis drug Ampyra and the U.S. regulator's refusal to review its other Parkinson's drug, Inbrija. (Reporting by Divya Grover in Bengaluru; Editing by Shounak Dasgupta)