Danny Nickerson, the 6-year-old Massachusetts boy whose request for birthday cards went viral last summer, has died of a rare brain tumor. 

Nickerson's death was announced by his family on their "Danny's Warriors" Facebook page Saturday. His mother's post said Danny died Friday at home after "a courageous 18-month battle."

The post says, "He is now cancer free and running and playing and laughing with God and all of the other precious children." It asks for prayers.

In October 2013, Nickerson was diagnosed with Diffuse Intrinsic Pontine Glioma (DIPG), an inoperable and chemotherapy-resistant brain tumor, MyFoxBoston.com reported. 

According to the report, less than 10 percent of patients survive 18 months past the diagnosis.  

A request for birthday cards for Nickerson, who loved to receive mail, drew an outpouring of support last July. 

The boy's mother took to Facebook to ask people to send her son a birthday card. The post went viral and Nickerson received hundreds of cards from around the world. 

The town's postmaster said Nickerson got more mail in one day than the rest of the town combined. The mail took four trucks and a U-Haul to bring home, MyFoxBoston.com reported. 

First responders from around the region helped Nickerson celebrate a birthday party at Gillette Stadium, where he attended a New England Patriots practice and met players.

The Associated Press contributed to this report.

Click for more from MyFoxBoston.com.