Ugandan actress Nikita Pearl Waligwa, who appeared in the 2016 Disney film “Queen of Katwe,” has passed away at 15, according to the BBC.

Waligwa played Gloria, a friend of the film’s protagonist, Phiona Mutesi, who explains the rules of chess to her. Based on a true story, “Queen of Katwe” is the story of Mutesi’s rise from poverty in Uganda as she learns to play chess, becoming a Woman Candidate Master after competing at the Chess Olympiad.

According to the BBC report, Waligwa was diagnosed with a brain tumor in 2016. Ugandan doctors were quoted to say that they didn’t have the necessary equipment to treat the tumor, so “Queen of Katwe” director Mira Nair reportedly organised an effort to fund her treatment in India. Waligwa was supposedly cleared the following year, but another tumor was discovered last year.