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Gene therapy reported to cure leukemia in young girl

Robin Wulffson MD's picture
acute lymphoblastic leukemia, ALL, cure, gene therapy, CTL109, T cells

On December 9, University of Philadelphia cancer researchers announced that they had cured leukemia in a young girl near death from leukemia. They reprogrammed seven-year-old Emily Whitehead’s own immune cells to attack an aggressive form of childhood leukemia, acute lymphoblastic leukemia (ALL). ALL is the most common childhood leukemia, and also the most common childhood cancer.

Pediatric oncologist Stephan A. Grupp, M.D., Ph.D., of The Children’s Hospital of Philadelphia, and colleagues from the University of Pennsylvania presented updated results of the clinical trial involving these engineered cells at the American Society of Hematology (ASH) annual meeting on December 9 in Atlanta, Georgia. The researchers noted that their innovative experimental therapy resulted in a complete response when Emily relapsed after conventional treatment. The innovative experimental therapy used bioengineered T cells, custom-designed to multiply rapidly in the patient, and then destroy leukemia cells. After the treatment, Emily’s doctors found that she had no evidence of cancer.

Dr. Grupp’s research builds on his ongoing collaboration with Penn scientists who originally developed the modified T cells as a treatment for B-cell leukemias. In August 2011, the Penn team reported on early results of a trial using this cell therapy in adult chronic lymphocytic leukemia (CLL) patients in August of 2011. Carl H. June, MD, of the Perelman School of Medicine at the University of Pennsylvania, leads this research group, which along with Dr. Grupp’s work, is presenting new data at the ASH meeting showing that nine of 12 patients with advanced leukemias in the clinical trial, including two children who responded to treatment with CTL019 cells.

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Emily is among the nine patients who responded to the therapy.is the 7-year-old with acute lymphoblastic leukemia (ALL). Dr. Grupp and his colleagues adapted the CLL treatment to combat ALL. Currently, oncologists (cancer specialists) can cure approximately 85% of ALL cases, the remaining 15% of such cases stubbornly resist treatment. The investigators note that the CTL019 therapy, formerly called CART19, represents a new approach in cancer treatment. T cells are the mainstay of the immune system; they recognize and attack invading disease cells. However, cancer cells can evade detection by T cells. Chimeric antigen receptor T cells (CAR T cells) are engineered to specifically target B cells, which become cancerous in certain leukemias, such as ALL and CLL, as well as types of lymphoma, another cancer of the immune cells.

CD19 is a protein found only on the surface of B cells. By creating an antibody that recognizes CD19, and physically connecting that antibody to T cells, the researchers have created a guided missile that locks in on and kills B cells, thereby attacking B-cell leukemia. In using the CTL019 treatment in his pediatric patient, Dr. Grupp found that the very activity that destroyed leukemia cells also stimulated a highly activated immune response called a cytokine release syndrome. The child became very ill and had to be admitted to the intensive care unit.

Grupp and his team decided to counteract these toxic side effects with the use of two immunomodulating drugs that reduced the overactive immune response and rapidly relieved the child’s treatment-related symptoms. These results were effective enough that this approach is now being successfully incorporated into CTL019 treatments for adults as well. The immunomodulating drugs did not interfere with the CTL019 therapy’s anti-leukemia benefits, which have persisted six months after the infusion of cell therapy. This persistence is essential, because the engineered T cells remain in the patient’s body to protect against a recurrence of the cancer. Dr. Grupp explained, “These engineered T cells have proven to be active in B cell leukemia in adults. We are excited to see that the CTL019 approach may be effective in untreatable cases of pediatric ALL as well. Our hope is that these results will lead to widely available treatments for high-risk B cell leukemia and lymphoma, and perhaps other cancers in the future.”

“This type of pioneering research addresses the importance of timing when considering experimental therapies for relapsed patients,” added Susan R. Rheingold, MD, one of the investigators in the Children’s Hospital program for children with relapsed leukemia. Sheadded, “To ensure newly relapsed patients with refractory leukemia meet criteria for options like CTL019, we must begin exploring these innovative approaches earlier than ever before. Having the conversation with families earlier provides them more treatment options to offer the best possible outcome.”

Reference: University of Pennsylvania