Fantasy sports site DraftKings will move its headquarters to Back Bay to make room for up to 275 new hires, bringing its local workforce up to 600 by mid-2019.

The 105,000-square-foot lease at Oxford Properties Group’s 500 Boylston St. will include an expanded media studio, as DraftKings relocates from 125 Summer St. in the Financial District.

The company said it expects to have at least 600 of its projected 700-person workforce based at the new headquarters.

Toronto-based Oxford Properties Group and J.P. Morgan Chase acquired the 1.3-million-square-foot 500 Boylston St.-222 Berkeley St. office tower in 2015 for $1.3 billion.

The DraftKings lease is part of an uptick in office leasing in the Back Bay, where vacancies soared in 2017 after a several large companies including Houghton Mifflin Harcourt and Partners HealthCare relocated to nearby submarkets and left behind 800,000 square feet of space.

But the neighborhood recovered quickly with 250,000 square feet of positive absorption during 2017, according to research by Colliers International Boston. The bulk of the leasing activity was at Boston Properties’ 200 Clarendon tower, including the first Boston offices for Chicago-based law firm Kirkland & Ellis LLP.

The rebound is expected to continue in 2018 with online furniture retailer Wayfair nearing completion of a lease for up to 400,000 square feet at 500 Boylston/222 Berkeley St. to augment its Copley Place headquarters, according to real estate sources.