17 December 2012
ByAppeared in BioNews 686
A seven-year-old girl with a highly aggressive form of leukaemia may have been 'cured' by an experimental therapy that harnesses the body's immune system to seek out and destroy the disease.
Emily Whitehead was recruited to a small scale clinical trial, involving 10 adults and two children at the Hospital of the University of Pennsylvania (HUP) and the Children's Hospital of Philadelphia (CHOP), USA after she relapsed twice following standard chemotherapy.
Emily's own T cells - specialised immune cells - were removed and genetically modified using an incapacitated version of the human immunodeficiency virus (HIV). Scientists used this virus to arm the T cells with a protein called chimeric antigen receptor (CAR). This molecule is capable of distinguishing cancer cells from the healthy ones by binding to another protein called CD19, which is found on the surface of cancer cells in leukaemia. Once reprogrammed in this way, Emily's T cells were injected back into her body, where they were able to detect and attack the cancer in the same way they would a foreign infection.
'Three weeks after receiving the treatment, she was in remission. Emily completely responded to her T cell therapy', said Dr Stephen Grupp, a paediatric oncologist at CHOP, whose team led the trial. '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.
Emily had acute lymphoblastic leukaemia (ALL) - the most common type of childhood cancer. While 85 percent of children with ALL recover after two years of standard chemotherapy, 15 percent remain resistant to such treatment. For this group, the only current option is to undergo bone marrow transplants, which carry a 20 percent mortality risk and often fails to rid the body of the disease. Professor Carl June, from the University of Pennsylvania's Abramson Cancer Centre, said: 'It is possible that in the future, this approach may reduce or replace the need for bone marrow transplantation'.
Nonetheless, the results are preliminary and three of the 12 patients in the trial did not respond to the therapy. Scientists are now calling for much larger clinical trials. The University of Pennsylvania, in partnership with Novartis, recently announced plans to build a Centre for Advanced Cellular Therapies (CACT) in Philadelphia to further explore the potential of T cell immunotherapy in the ongoing battle against cancer.