Frank DePaola, who stepped up to lead the MBTA as it struggled to perform amid severe winter weather in 2015, announced Monday he will retire to fight his cancer. 

The former highway chief took over the role as the T's general manager in February 2015 after the unexpected departure of former GM Beverly Scott, who resigned after snow and cold ground the T to a halt that winter.

DePaola has been battling cancer for months, according to the T. He will retire at the end of June to focus on his health, transit officials said. 

RELATED: Overtime crackdown at the MBTA is paying off: Report

“It has been an honor to serve as general manager during this critical period and to work with so many dedicated colleagues and employees who have helped the MBTA improve service, become more resilient and fix the T’s aging assets,” DePaola said in a MassDOT statement announcing his departure. 

MassDOT has appointed MBTA Chief Administrator Brian Shortsleeve, a former Marine and business executive, as acting general manager as of July 1, and that MBTA Chief of Operations Jeff Gonneville would take on more responsibility, including oversight of safety and accessibility at that time.

Shortsleeve has handled the financial side of the MBTA, seeking to align expenses and revenues by bringing in more business and cutting down on overtime. Gonneville was promoted from chief mechanical officer to chief operating officer in the first year of the Baker administration.

Beset by managerial quandaries and a more than $7 billion repair backlog, the MBTA has had regular turnover at the top. In July, Shortsleeve will become the seventh leader of the transit system in eight years, according to information supplied by the T.

State House News Service contributed to this report.