"The Normal Heart" has added Jonathan Groff and Joe Mantello to its cast, according to Deadline.
The actors join Julia Roberts, Mark Ruffalo, Matt Bomer, Jim Parsons and Taylor Kitsch in Ryan Murphy's adaptation of the Tony award-winning play.
Mantello will appear as Mickey Marcus, "an instrumental member of the Gay Men’s Health Crisis," while Groff will play the closeted banker Bruce Niles' (Kitsch) lover.
"The Normal Heart," which is being adapted for HBO, centers on the HIV-AIDS epidemic in New York City in the early 1980s.
"We are so proud to be involved with this monumental project,” HBO programming president Michael Lombardo said when the project was announced in January. “Ryan has assembled an extraordinary cast to bring Larry Kramer’s landmark theatrical achievement to the screen for the first time, and we couldn’t be more thrilled to bring this important film to HBO.”
"The Normal Heart" is set to debut on HBO in 2014.