The three-year-old has been receiving treatment in Oklahoma at the ProCure Proton Beam Therapy Centre since flying out with parents, Raluca and Philip, at the end of November.
More than £150,000 was raised to fund the youngster’s treatment after he was turned down by the NHS, with support from charity Kids ‘n’ Cancer and the Wiltshire Times.
Mike Hyman, co-founder of Kids ‘n’ Cancer, said: “I spoke to them on Sunday and everything is going to plan.He should be receiving his last treatment on January 15 and could be coming home the following week, but it depends how long they want him to stay after.
“He could still spike a temperature and we always have to be aware of this.
“He has been amazing though, every Saturday and Sunday when he doesn’t go for treatment he asks “why am I not going to get better?”.
“Raluca didn’t believe me when I said one week in he won’t be bothered about you being there and now he’s quite happy to toddle off with the nurse and that will be it."
“He’s settled and everything is going in the right direction.
“When he gets back after three months he will have his first scan but that’s not a definitive scan.
“The radiation might have made the tumour swell and so it will be a bigger measurement but the definitive scan will come at six months, when any swelling will have gone and consequently they will be able to measure the tumour.
“And we will have to take it from there.”