you very obviously know very little about healthcare in the UK. private health companies exist in the UK and very profitable they are too. pretty much any medical procedure carried out by the NHS can be done privately - cancer care, orthopedic work, anti-natal, childbirth, heart surgery - you name it.
if you wish to look a fool then carry on, otherwise read up on your subject before commenting.
the drug was tested for the first time on humans by giving it to healthy adult males. if there were to be side effects probably better to find out what those side effects might be before discovering them in the treatment of a critically ill four year old with lukemia.