Leah Still underwent a stem cell transplant about a month ago to treat her cancer, and suffered an unspecified setback or complication.

Leah was diagnosed in June 2014 with Stage 4 neuroblastoma, and only given a 50-50 chance of survival. On Friday, Devon Still took to social media and asked fans to pray for his daughter.

Leah’s courageous spirit as she endured multiple treatments and procedures has served as an inspiration to many people around the world. In late March, Still announced that Leah was officially in remission.

Still posted on Instagram on May 29 that Leah is battling Hepatic veno-occlusive disease, or VOD, a common and potentially serious side effect of stem cell transplants that impacts the liver. Still said doctors caught it early.

Along with asking for prayers, Still wrote in his Instagram post, “As you can imagine our minds are all over the place but we're going to try and remain positive!”