"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 Children's 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 Children's Hospital of Philadelphia, and a professor of Pediatrics at the Perelman School of Medicine at the University of Pennsylvania. Grupp said the appearance of the CD19-negative leukemia cells in the second child may have resulted from her prior treatments. Unlike Emily, the second patient had received an umbilical cord cell transplant from a matched donor, so her engineered T cells were derived from her donor (transplanted) cells, with no additional side effects. Oncologists had previously treated her with blinatumomab, a monoclonal antibody, in hopes of fighting the cancer. The prior treatments may have selectively favored a population of CD19-negative T cells. "The emergence of tumor cells that no longer contain the target protein suggests that in particular patients with high-risk ALL, we may need to broaden the treatment to include additional T cells that may go after additional targets," added Grupp.

Stephan Grupp, MD PhD Children's Hospital of Philadelphia

Both had been treated and had then relapsed, said Stephan Grupp, director of Translational Research in the Center for Childhood Cancer Research at the Children's Hospital of Philadelphia. He presented research on their care at the hematology meeting. One of the girls has been in complete remission in the eight months since her treatment. The other had a remission of "a few months" before relapsing again, Grupp said. The younger girl had severe side-effects. Previous studies have documented severe, flu-like illness in patients treated with their pumped-up immune cells. The 7-year-old's severe reaction helped explain what was happening, Grupp said. Her levels of an inflammatory protein called IL-6 were very high, 998 times her ordinary level. His group treated her with Roche's Actemra, approved for rheumatoid arthritis, which targets the protein. Because her levels of another inflammatory protein called TNF were high, she was also treated with Amgen and Pfizer's Enbrel. "The next morning, she was dramatically better," Grupp said.

Dr. Stephan A. Grupp, Director of the Center for Childhood Cancer Research at Children's Hospital of Philadelphia, testified that CURE has helped fund his groundbreaking childhood leukemia research, specifically immunotherapy. "In addition to working to develop these cells as a treatment and testing them in my lab, I am a practicing pediatric oncologist, so my main goal is to bring these new treatments to kids with no hope for a cure," he testified.

Dr Stephan Grupp, Director of the Centre for Childhood Cancer Research at The Children's Hospital of Philadelphia, told CBS: "We've treated the first couple of patients and we've been blown away by the results".