Updated

A New Jersey teen undergoing treatment for leukemia is unable to attend the Academy of Country Music Awards as Taylor Swift's date, the country-pop star confirmed Saturday.

"Just talked to Kevin Maguire [sic]. He's not well enough to join me at the ACMs," Swift tweeted. "Please keep him in your thoughts. I'll make it up to you, Kevin!"

Swift invited McGuire to the ceremony after his sister launched a Facebook petition in February to get her 18-year-old brother a date with the singer for his June prom at Sterling High School in Somerdale, N.J.

PHOTOS: Taylor Swift.

The 22-year-old star said she would not be able to make it to McGuire's prom but invited him to be her date at the Academy of Country Music Awards, set for Sunday night.

McGuire accepted, but he was hospitalized Friday night due to a high fever and was unable to make the trip to Las Vegas for the awards show on Saturday, the Cherry Hill Courier-Post reported.

He is battling a relapse of leukemia -- after first being diagnosed with the disease five years ago -- and recently underwent five chemotherapy sessions of five hours each, which drastically compromised his immune system and lowered his blood cell and hemoglobin counts.