Oxford Properties Group wants to transform its 159K SF downtown office formerly occupied by WeWork into labs.

Oxford filed Monday a letter of intent with the Boston Planning and Development Agency to redevelop 155K SF at 745 Atlantic Ave. after WeWork vacated and left it approximately 75% vacant.

“We believe this approach, which provides Oxford the flexibility to accommodate a variety of tenants according to future demand, will limit the duration and impacts of the vacancy,” Oxford Vice President and Boston Head of Development Mark McGowan wrote in the letter.

The coworking giant has denied it owes Oxford more than $1.8M in back rent after the developer sued WeWork in May over its February departure from its 131K SF location. It is unclear which tenant occupied the remainder of the building. An Oxford representative didn't respond to a request for comment Tuesday afternoon.

Oxford would upgrade the building’s mechanical, engineering, plumbing and other infrastructure to reach new sustainability standards and expand a first floor 1,800 SF retail space into 4,100 SF, McGowan wrote.

Asking rents for Class-A office space in South Station averaged $57 per SF in Q2, according to Newmark, while life sciences spaces in downtown averaged $95 per SF. Oxford said in its suit that WeWork paid a yearly rent of $7.8M, or approximately $59 per SF.

WeWork admitted to vacating the space in February, but in a June response to Oxford's suit, attorneys from Boston-based Lurie Friedman LLP representing the coworking company argued it was within its rights to vacate the space and contested the validity of the lease.

WeWork vacated its space at 745 Atlantic Ave. in February, a fact the coworking giant admitted in a June response to Oxford’s lawsuit in Suffolk Superior Court. However, WeWork denies allegations it vacated improperly and is contesting the lease. A lawyer representing WeWork alleged in their response that Oxford didn’t submit every page of the lease document in their original suit.