In this trailer for Love, Gilda, an awed Amy Poehler, Bill Hader and Melissa McCarthy hold Gilda Radner’s handwritten letters as if they’re treasures that could turn to dust with the slightest breeze. “I can’t believe this is her handwriting,” says Poehler.

Directed by Lisa D’Apolito, the documentary, which debuted at this year’s Tribeca Film Festival, chronicles the beloved Saturday Night Live cast member – one of the original Not Ready For Prime Times Players – and was put together with the blessing of the Radner estate, which provided D’Apolito a collection of diaries, personal audio and videotapes documenting Radner’s childhood, her comedy career, her relationships and ultimately, her struggles with cancer. The never-before-seen-or-heard footage and journal entries form the narrative spine of the documentary, allowing Gilda to tell her own story.

In addition to Hader, McCarthy and Poehler, the friends and admirers making appearances include Anne Beatts, Chevy Chase, Janis Hirsch, Judy Levy, Lorne Michaels, Laraine Newman, Michael Radner, Maya Rudolph, Paul Shaffer, Martin Short, Rosie Shuster, Cecily Strong and Radner’s longtime SNL writing partner Alan Zweibel, among others.

“I always felt that I could do anything if people were laughing,” we hear Gilda say in the trailer. The documentary covers her career – including her Second City days, Broadway, films and, of course, break-out stardom on SNL – as well as the personal challenges, including an eating disorder and, of course, the cancer that she fought so tirelessly and publicly.

Love, Gilda is produced by Bronwyn Berry, Meryl Goldsmith and James Tumminia.

Magnolia Pictures and CNN Films will release Love, Gilda to theaters September 21. Check out the trailer above.