Five-year-old Ashya King "had a very good night" in a Spanish hospital last night, hospital staff told ITV News.
Ashya was "stable" and his mother Naghemeh was by his bedside all night, they said.
His parents meet with his doctors everyday and they are expected to do so again today.
The head of the police force which applied for a European Arrest warrant against the parents of Ashya King has now urged their release.
A British mother whose son's life was saved by proton therapy has told ITV that she defied NHS doctors' advice to pursue the treatment.
The parents of Ashya King said they took him out of a hospital to seek proton beam treatment which is not available under the NHS.