According to new research from The Children's Hospital of Philadelphia and the University of Pennsylvania, two children with an aggressive form of childhood leukemia achieved a complete response after being treated with an innovative cell therapy. In the study, both patients' immune systems were reprogrammed to rapidly multiply and destroy leukemia cells.

The study appeared in the April 18 issue of The New England Journal of Medicine.

Both patients were treated for acute lymphoblastic leukemia (ALL), an aggressive childhood leukemia. The research team used a relatively new approach in cancer treatment: immunotherapy, in which the immune system is manipulated to increase its cancer-fighting capabilities. The investigators engineered T cells - the workhorses of the immune system, which recognized and attack invading disease cells - to selectively kill another type of immune cell called B cells, which had become cancerous.

One of the patients treated, 7-year-old Emily Whitehead, was the subject of a media frenzy last year when the experimental therapy led to her dramatic recovery after she relapsed following conventional treatment. Eleven months after receiving bioengineered T cells, Emily remains healthy and cancer-free.

The other patient, a 10-year-old girl who also had a complete response to the same treatment, suffered a relapse two months later when other leukemia cells appeared that did not harbor the specific cell receptor targeted by the therapy.

The current study builds on Dr. Grupp's ongoing collaboration with Penn Medicine scientists - led by the study's senior author, Carl H. June, MD - who originally developed the modified T cells as a treatment for B-cell leukemias in adults. The Penn team reported on early successful results of a trial using this cell therapy in three adult chronic lymphocytic leukemia patients in August of 2011.

Though early results have been promising, the research team continues to their approach to using this new technology and to explore why some patients may not respond to the therapy or may experience a recurrence of their disease.