<span style="color: #222222;">A teenage girl's incurable cancer has been cleared from her body with the first use of a revolutionary new type of medicine in a UK hospital. All other treatments for the girl's leukemia had failed. Doctors at London's Great Ormond Street Hospital used a technology called "base editing", invented only six years ago, to perform a feat of biological engineering to build her a new living drug. Six months later the cancer is undetectable, but the teenager is still being monitored in case it comes back.<br />''<br />''Alyssa, who is 13 and from Leicester, UK, was diagnosed with T-cell acute lymphoblastic leukemia in May last year. Her cancer was aggressive. Chemotherapy, and then a bone-marrow transplant, were unable to rid it from her body, the BBC reported.<br />''<br />''Base editing allows scientists to zoom into a precise part of the genetic code and then alter the molecular structure of just one base, converting it into another and changing the genetic instructions.<br />''<br />''The large team of doctors and scientists used this tool to engineer a new type of T-cell that was capable of hunting down and killing Alyssa's cancerous T-cells.  These T-cells are supposed to be the body's guardians -seeking out and destroying threats but for Alyssa, they had become the danger and were growing out of control.</span><br />