UNLIKELY WEAPON:
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POLIO VIRUS. AT FIRST SHE WAS SKEPTICAL. >> I WAS JUST GOING TO GO HOME AND BURY MY HEAD IN THE SAND, AND THEN I REALIZED, NO, NO, I'M NOT SUPPOSED TO DO THAT. >> Reporter: FOR THE LAST FOUR YEARS, " 60 MINUTES" HAS CHARTED THE JOURNEY OF DOCTORS AND PATIENTS TURNED MEDICAL PIONEERS. THE POLIO VIRUS, GENETICALLY MODIFIED SO IT CAN'T CAUSE POLIO, IS INJECTED DIRECTLY INTO THE TUMOR, ATTACHING TO A PROTEIN ON THE CELL'S SURFACE. IT BEGINS ITS ATTACK ON THE TUMOR, THEN JUMP- STARTS THE IMMUNE SYSTEM TO FINISH THE JOB. DR. DARRELL BIGNER IS PART OF THE TEAM AT DUKE. SO IT'S KIND OF A ONE- TWO PUNCH? >> EXACTLY. BUT THE MOST IMPORTANT PART WE BELIEVE ACTUALLY IS THE SECONDARY IMMUNE RESPONSE. >> Reporter: ONE MONTH AFTER TREATMENT... >> IT STARTED TO BREAK THE TUMOR UP. >> Reporter: HUSBAND MARK PUFFER. >> THEY CALL DEBBIE A RAPID RESPONDER. >> RAPID RESPONDER. >> Reporter: PUFFER'S IMPROVEMENT WAS NOT A FLUKE. 21 % OF 61 PATIENTS WERE STILL ALIVE THREE YEARS AFTER TREATMENT COMPARED TO JUST 4 % TYPICALLY SEEN WITH STANDARD CARE. COULD YOU EVER HAVE IMAGINED HAVING A RESPONSE RATE THAT HIGH? >> IT'S JUST MIND BLOWING TO US THAT HAVE BEEN WORKING ON IT FOR SO LONG, BECAUSE THIS IS BASED ON ABSOLUTELY BEDROCK SCIENTIFIC PRINCIPLES. >> Reporter: LAST YEAR PUFFER WAS RETREATED WHEN HER TUMOR SHOWED SIGNS OF RETURNING. >> MAYBE THIS TIME WE KILLED THE DRAGON. I'M NOT SURE. >> Reporter: DESPITE SOME MEMORY AND VISION PROBLEMS, SHE CAN NOW SEE A FUTURE. >> I'M MEANT TO BE HERE FOR A REASON. I DON'T KNOW WHAT THAT REASON IS, BUT I'M SURE GOING TO HANG AROUND TO FIND OUT. >> Reporter: DR. JON LaPOOK, CBS NEWS, NEW YORK.
