Japanese drug maker Astellas Pharma Inc. extended for a second time its $379 million buyout offer for Ocata Therapeutics Inc. of Marlborough, after it failed to win enough shareholder support.

The tender offer, now set to expire 5 p.m. on Feb. 9, leaves the terms of $8.50-a-share deal unchanged.

Astellas said in a regulatory filing Friday that 47 percent of Ocata’s outstanding shares have been tendered, up from about 36 percent a month ago. Astellas needs a simple majority of the shares to take control of Ocata.

Many investors in Ocata have complained that the Astellas bid — representing a nearly 80 percent premium over Ocata’s value on Nov. 10, when the tender offer was disclosed — undervalues Ocata.

Robert Weisman

GLOBE STAFF

Robert Weisman can be reached at robert.weisman@globe.com. Follow him on Twitter @GlobeRobW.