Development of the Suffolk Down racetrack is moving forward whether or not Amazon opts to build its second headquarters in Boston.

HYN Investment Group, on behalf of the McClellan Highway Redevelopment, submitted a letter of intent on Nov.  17 to the Boston Planning and Development Agency regarding the Suffolk Downs Redevelopment project, which launches a formal review of the project.

The project involves redevelopment of the 161-acre underutilized thoroughbred horse racing facility located in East Boston and Revere, according to the letter. The project site was also recently identified in the Boston 2030 Plan as a key site for Boston’s future growth and targeted for a significant new transit oriented mixed-use development district.

Submission of the letter of intent comes after several months of meetings in East Boston and Revere by HYM to start garnering support. HYM, which is led by a former Boston Redevelopment Authority director, Tom O’Brien, bought the site earlier this year for $151 million from the racetrack owners, who had lost their bid to put a casino there, the Boston Globe reported.

“Redevelopment of the Site provides a unique opportunity to create additional housing, spur economic development, and improve connections between several adjoining neighborhoods,” stated O’Brien in the letter.

The letter references plans for developing a new neighborhood with two retail squares built near the MBTA Blue Line Stations, 40-acres of open space, and new bicycle path connections and bike share Hubway Stations.