Image courtesy of Gensler

The first life science development in Somerville’s Brickbottom neighborhood has secured an initial tenant in a California biopharma company.

Ultragenyx will occupy 42,580 square feet at 100 Chestnut, a speculative 208,600-square-foot office-lab building that is scheduled for completion in mid-2023.

Developer North River Leerink received a $192.5 million construction loan from Square Mile Capital in June for the project. It also owns the nearby 86 Joy St. property and is eyeing a potential three-building redevelopment, an executive told Banker & Tradesman in June.

Located in a federal Opportunity Zone and next to an MBTA Green Line Extension station, Brickbottom has the potential to become Somerville’s “next downtown,” according to consultants advising the city on a planning study of the industrial neighborhood near the Cambridge line. The study is designed to guide proposed rezoning for higher-density development including offices, labs and multifamily housing.

Novato, California-based Ultragenyx reported second-quarter revenues of $89.3 million and a net loss of $158.2 million.

The firm has a pharmaceutical development and quality control facility in Woburn and gene therapy headquarters in Cambridge. In 2020, Ultragenyx broke ground in 2020 on a 100,000-square-foot manufacturing facility on Crosby Drive in Bedford.

The firm did not immediately respond to a request for comment.

The 100 Chestnut St. lease runs for six years and four months, according to a filing with the Middlesex Registry of Deeds, and has an expansion option for an additional 18,353 square feet.