UPDATE 2-Axovant's Alzheimer's drug fails in late-stage trial, shares plummet

(Adds details on other trials, Alzheimer's data; updates shares)

Sept 26 (Reuters) - Axovant Sciences Ltd's drug failed to improve cognitive abilities and daily activities in Alzheimer's patients, in the latest setback to finding a treatment for the memory-robbing disease that affects millions in the United States.

The company's shares plunged 69 percent in premarket trading on Tuesday. They had nearly doubled in value this year.

The drug, intepirdine, was being tested in a late-stage trial in patients with mild-to-moderate Alzheimer's who did not respond to background therapy, and was compared with a placebo.

The reversal comes more than seven months after Denmark's Lundbeck said its experimental Alzheimer's drug failed in two late-stage trials.

Axovant's drug is similar to Lundbeck's idalopirdine, and belongs to a class of drugs called 5-HT6 antagonist.

The 5-HT6 antagonist works by blocking the 5-HT6 receptor to help release acetylcholine, a neurotransmitter needed for normal cognition.

The Street is likely to buy the pullback, given that the negative result was not completely unexpected, Jefferies analysts wrote, adding the company is likely to pivot towards another program.

U.S. deaths from Alzheimer's jumped more than 50 percent from 1999 to 2014, and the rates are expected to rise, reflecting the nation's aging population and increasing life expectancy, according to American researchers.

Axovant's intepirdine did not show statistically significant improvement in cognition and showed no difference in daily living activities in patients, failing the two main goals of the trial.

The drug, however, showed some improvement in one of the secondary goals, the company said.

Axovant's shares were trading at $7.11 in premarket trading on Tuesday.

(Reporting by Divya Grover and Manas Mishra in Bengaluru; Editing by Sriraj Kalluvila)