Had 48 hours or so left when she finally got the therapy. Months later, no sign of cancer and she doesn't have HIV. SCIENCE WINS AGAIN. Not prayer, but science.
Doctors suggested they sign Emily up to a clinical trial that would use a disabled form of HIV to carry cancer-fighting genes into her T-cells (disease fighting cells). The hope was that this would re-programme her immune system to recognise the cancer cells and start killing them.
Several adults had already been enrolled in the study at the Hospital of the University of Pennsylvania and had responded well, but as it was so new the treatment wasn't without risks. But time was running out for Emily, who is also known as Emma.
Mr Whitehead said: 'We were told that we were down to 48 hours of making a decision or she could start having organ failure.'
They comforted themselves with the knowledge that even if the treatment didn't work, it would provide doctors with information that could help them save other sick children.
So on April 17, the then six-year-old became the first child to have the therapy known as CTL019.
'Emily completely responded to her T-cell therapy. We checked her bone marrow for the possibility of disease again at three months and six months out from her treatment, and she still has no disease whatsoever. The cancer-fighting T-cells are still there in her body.'
He added that they need to see the remission go on for a couple of years before they can think about whether she is cured or not.
But, after spending years in treatment, Emily went home in June and now enjoys going to school, playing football and walking her dog Lucy.