Thousand Oaks city officials and business leaders came out Monday morning to witness the grand opening of Atara Biotherapeutics Inc.'s new research and development facility, dubbed ATOM, in the Conejo Spectrum Business Park.

“I am excited for you to an extreme degree, and I’m also green with envy,” Dr. Richard O’Reilly, an Atara medical advisory board member who pioneered the T-cell therapies that the company is trying to commercialize, told Atara employees in a speech. “This is an extraordinary facility, and you should all be very proud.”

ATOM stands for Atara T-Cell Operations and Manufacturing. At nearly 91,000 square feet, the facility will be the main hub for manufacturing the company’s T-cells, which are designed to destroy cancers associated with the Epstein-Barr virus. It is an addition to the company’s research and development facilities in Westlake Village, where Atara currently has 65 workers. The company will hire more than 100 new employees as part of the expansion.

The city of Thousand Oaks had been working with Atara for a couple of years to bring the facility to fruition, City Manager Andrew Powers said.

“From a broader economic landscape standpoint, this is such a wonderful addition to our portfolio,” Powers said. “For years we’ve always had Amgen as the major player in town. ... This provides another footprint in a new and growing area in the biotech space that will broaden the job opportunities locally and have an overall benefit to our local economy.”

Atara is headquartered in South San Francisco. Shares of the company (ATRA) fell $1.05, or about 2.5 percent, on Monday to close at $41.20 on the Nasdaq.