LITTLE GIRL. REHEMA ELLIS HAS BEEN FOLLOWING HER STORY.
>> Reporter: TODAY'S LANDMARK DECISION STARTED WITH A YOUNG
PIONEER, EMILY WHITEHEAD, NOW LITERALLY THE TEXTBOOK
EXAMPLE OF THIS GROUNDBREAKING THERAPY.
LOOK AT THIS FACE. THIS SAYS I'M HAPPY. >> COULDN'T BE MORE
PROUD. >> Reporter: WE MET EMILY A YEAR AND A
HALF AGO AT AGE 10, STILL CANCER-FREE AFTER BEING DIAGNOSED
WITH AN ACUTE FORM OF LEUKEMIA WHEN SHE WAS 5.
>> AT ONE POINT THE DOCTOR CAME IN AND SAID, YOU NEED TO CALL
YOUR FAMILY IN BECAUSE EMILY'S NOT GOING TO BE HERE TOMORROW.
>> Reporter: WHAT DOCTORS AT THE UNIVERSITY OF
PENNSYLVANIA AND CHILDREN'S HOSPITAL OF PHILADELPHIA DEVELOPED
THE CAR T CELL TREATMENT. EMILY WAS THE FIRST
CHILD IN THE WORLD TO RECEIVE IT. >> SHE'S CANCER FREE.
AND I COULDN'T BELIEVE IT. I THOUGHT IT WAS A
DREAM. >> Reporter: HERE'S HOW IT WORKS.
FROM A BLOOD SAMPLE, A PATIENT'S OWN IMMUNE CELLS ARE SEPARATED
OUT AND THEN GENETICALLY REPROGRAMMED, TURNING
THEM INTO SUPERFIGHTERS THAT HUNT OUT AND DESTROY
CANCER CELLS. AT THE FDA HEARING TODAY, FIGHTING BACK
TEARS, TOM WHITEHEAD TESTIFIED NEXT TO EMILY.
>> IF YOU WANT TO SEE WHAT A CURE LOOKS LIKE, SHE'S STANDING
RIGHT BESIDE ME. >> Reporter: THIS FALL THE FULL FDA IS
EXPECTED TO APPROVE THIS TREATMENT FOR RELAPSING LEUKEMIA IN
CHILDREN AND YOUNG ADULTS. IT'S GRUELING, BUT 83%
OF PATIENTS WENT INTO REMISSION. THE ULTIMATE GOAL, TRY
IT ON OTHER CANCERS. >> IT'S HARD FOR ME TO EVEN ARTICULATE HOW
EXCITING THIS IS. THIS IS -- EVERYBODY HAS BEEN WORKING
TOWARD THIS FOR SO LONG. >> Reporter: FOR EMILY
WHITEHEAD, TODAY'S DECISION IS ABOUT HOPE.
>> IT'S KIND OF EXCITING BECAUSE IT WILL GET THE TREATMENT
TO A LOT MORE KIDS. >> Reporter: A HISTORIC STEP IN
