Parents who raised £350,000 to treat their son's one-in-a-million cancer say they are "devastated" to learn he cannot be cured.
Dawson Willcock, who is nearly two, was diagnosed with hepatoblastoma, a form of liver cancer, in January and a therapy in the US was his best chance.
But doctors have now said they do not believe the drug will stop the disease.
Dawson's mother, Wendy, said they "still believe in miracles" but may donate the money to other children.
The family, from Sutton-in-Ashfield, Nottinghamshire, began the 'Dollar for Dawson' appeal after UK-based chemotherapy failed.
He has the same type of cancer as singer Michael Buble's son and Dawson's case attracted national media attention.
A pioneering drug trial in Cincinnati seemed to offer hope but the family has now been told it will only extend his life for a short time.
Mrs Willcock said: "It has all been bad news. It is news you don't want when you are focusing on your last chance and it gets taken away.
"But we have raised an amazing amount of money and that shows the support of the community and even strangers.
"That helps. We get strength from everybody and Dawson keeps us going and the support keeps us going.
"People say 'keep your chin up, keep fighting' and we do."
The family said if they do not spend the money on Dawson, it will be used for other children, cancer research and a holiday home for affected families.
They have asked for hearts to be sent to the family as a token of support.