PHILDELPHIA Two children with an aggressive form of childhood leukemia had a complete remission of their diseaseshowing no evidence of cancer cells in their bodiesafter treatment with a novel cell therapy that reprogrammed their immune cells to rapidly multiply and destroy leukemia cells. A research team from The Childrens Hospital of Philadelphia and the University of Pennsylvania published the case report of two pediatric patients Online First today in The New England Journal of Medicine. It will appear in the April 18 print issue.

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.

This study describes how these cells have a potent anticancer effect in children, said co-first author Stephan A. Grupp, M.D., Ph.D., of The Childrens Hospital of Philadelphia, where both patients were treated in this clinical trial. However, we also learned that in some patients with ALL, we will need to further modify the treatment to target other molecules on the surface of leukemia cells.

Grupp is the director of Translational Research for the Center for Childhood Cancer Research at The Childrens Hospital of Philadelphia, and a professor of Pediatrics at the Perelman School of Medicine at the University of Pennsylvania. Michael Kalos, Ph.D., an adjunct associate professor in the department of Pathology and Laboratory Medicine and director of the Translational and Correlative Studies Laboratory in the Perelman School of Medicine at Penn, is co-first author on the study.

The current study builds on Grupps ongoing collaboration with Penn Medicine scientists who originally developed the modified T cells as a treatment for B-cell leukemias. The Penn team reported on early successful results of a trial using this cell therapy in three adult chronic lymphocytic leukemia (CLL) patients in August of 2011. Two of those patients remain in remission more than 2 years following their treatment, and as the Penn researchers reported in December 2012 at the annual meeting of the American Society of Hematology, seven out of ten adult patients treated at that point responded to the therapy. The team is led by the current studys senior author, Carl H. June, M.D., the Richard W. Vague Professor in Immunotherapy in the department of Pathology and Laboratory Medicine and the Perelman School of Medicine at the University of Pennsylvania and director of Translational Research in Penns Abramson Cancer Center.

Were hopeful that our efforts to treat patients with these personalized cellular therapies will reduce or even replace the need for bone marrow transplants, which carry a high mortality risk and require long hospitalizations, June said. In the long run, if the treatment is effective in these late-stage patients, we would like to explore using it up front, and perhaps arrive at a point where leukemia can be treated without chemotherapy.

The research team colleagues adapted the original CLL treatment to combat another B-cell leukemia: ALL, which is the most common childhood cancer. After decades of research, oncologists can currently cure 85 percent of children with ALL. Both children in the current study had a high-risk type of ALL that stubbornly resists conventional treatments.

The new study used a relatively new approach in cancer treatment: immunotherapy, which manipulates the immune system to increase its cancer-fighting capabilities. Here the researchers engineered T cells to selectively kill another type of immune cell called B cells, which had become cancerous.

T cells are the workhorses of the immune system, recognizing and attacking invading disease cells. However, cancer cells fly under the radar of immune surveillance, evading detection by T cells. The new approach custom-designs T cells to see and attack the cancer cells.

The researchers removed some of each patients own T cells and modified them in the laboratory to create a type of CAR (chimeric antigen receptor) cell called a CTL019 cell. These cells are designed to attack a protein called CD19 that occurs only on the surface of certain B cells.

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T- Cell Therapy Eradicates an Aggressive Leukemia in Two Children

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