Sylvester Stallone’s son with his first wife Sasha Czack, Sage was found dead in his Los Angeles home on Friday by an employee and a relative.
No suicide note was found but an autopsy is to be performed, establishing a cause of death is likely to take several weeks while toxicology tests are performed.
Sage Stallone made his acting debut in 1990’s Rocky V. He was due to get married this weekend.
Reports say he lived his life as her hermit and could have been dead seven days although his facebook page was updated more recently.
Sylvester Stallone has asked that people respect “my talented son’s memory and feel compassion for his loving mother Sasha.”
He also added: “This agonising loss will be felt for the rest of our lives…Sage was our first child and the centre of our universe and I am humbly begging for all to have my son’s memory and soul left in peace.”