DETROIT -- Gavin Rupp, who threw a first pitch to Nationals outfielder Bryce Harper earlier this month, lost his battle with brain cancer on Tuesday, a team spokesman confirmed after the team's 5-1 loss to the Tigers. He was 13 years old. Harper was not available for comment.

Rupp, who was from Ashburn, Va., was first diagnosed with brain cancer in February 2011, when doctors removed a malignant tumor from his brain. A year of chemotherapy followed. Gavin was cancer-free for six months before the tumor reappeared. Again, it was removed.

Then, in late April, the cancer returned a third time. Gavin's father, Chris, was told that his son had a 10-percent chance to live.

"The surgery risk at this point," Chris Rupp said at the time, "You really can't do much."

Gavin Rupp's favorite team was the Washington Nationals and his favorite player was Harper. Rupp was able to meet his favorite player on July 5 before the Nationals played the Padres. Harper hung out with Rupp and his family for about an hour. Harper also gave Rupp an autographed hat, a glove and a bat. Harper also received an autographed baseball from Rupp.

For the past two years, the Nationals have partnered with Kyle's Kamp and the Children's National Medical Center to host a children's baseball tournament at Nationals Park. Hundreds of little league teams from up and down the East Coast raised money to benefit cancer research. The six teams that raised the most money played against each other at the stadium.

Gavin's team played at Nationals Park last year as the tournament raised more than $250,000. This year, it raised nearly $370,000. Chris Rupp has worked with Rob Hahne, the founder of Kyle's Kamp, to make the tournament an annual success.