Cynthia Nixon joins 'The Big C'

By and large, cancer isn’t a popular theme in the comedy world, but Showtime's darkly funny “The Big C” may change that.

Laura Linney stars in the forthcoming series as the repressed Cathy, a teacher, wife and mother from the suburbs who gets bolder and braver after she’s diagnosed with cancer, and "Sex and the City's" Cynthia Nixon will be along for the ride in a four-episode arc.

Nixon will play the flaky Rebecca, the “long-lost college roommate" of Linney's character "who re-enters her life and shakes things up in a wild way,” according to a statement.

Oliver Platt will portray Cathy’s “immature, but well-meaning husband,” while Oscar-nominated Gabourey Sidibe has been cast as a smart aleck student (so long, “Precious”). The trailer promises more than one hilarious student-teacher standoff.

“The Big C” was created and written by Darlene Hunt, and Bill Condon (of “Dreamgirls” fame) directed the pilot.

The 13-episode series, set to premiere August 16 at 10:30 p.m. PT/ET, is currently shooting in Stamford, Connecticut.