An innovative cell therapy against a highly aggressive form of acute lymphoblastic leukemia (ALL) continues to show highly promising results in children treated in a pilot study. At 1 month after treatment, 92% of the 39 children receiving bioengineered T cells had no evidence of cancer, with this complete response persisting in some cases for more than 2 years.
The personalized cell therapy reprograms a patient’s immune system and offers the potential of long-term success.
“As we continue to follow children in this study, we see exciting results for patients who have exhausted their other treatment options,” said study leader Stephan A. Grupp, MD, PhD, a pediatric oncologist at The Children’s Hospital of Philadelphia and a professor of Pediatrics at the Perelman School of Medicine of the University of Pennsylvania. Grupp described outcomes and follow-up results of this pilot clinical trial for pediatric patients with ALL at the 56th annual meeting of the American Society of Hematology in San Francisco, California.
Grupp and colleagues reported that of the 39 children treated, 36 (92%) had complete responses 1 month after treatment. Of those 36 patients, 25 (69%) remained in remission at a median follow-up of 6 months after treatment. There were 10 relapses among the 36 patients with complete responses; five patients with relapsed disease died.
Grupp is an ongoing collaborator with colleagues at Penn Medicine, who offer this personalized cell therapy as a treatment for adult patients with other types of cancer.
All the patients had high-risk ALL that recurred after initial treatment or resisted that treatment from the start. Patients received bioengineered hunter T cells called CTL019 cells.
The first child to undergo this therapy, a 9-year-old girl, remains cancer-free since her T cell treatment in April 2012, and continues to enjoy normal childhood activities such as going to school and playing with her dog.
A relatively new approach in cancer treatment, this type of immunotherapy modifies T cells, the workhorses of the body’s immune system, to attack B cells, other immune cells that become cancerous in specific leukemias such as ALL. Bioengineered T cells function as cancer hunters, killing the leukemia cells that normally evade regular T cell surveillance.
Researchers first extract a patient’s own T cells. They then use bioengineering techniques to reprogram each patient’s T cells into chimeric antigen receptor cells (CTL019 cells) and are custom-designed to bind to the CD19 protein which exists only on the surface of B cells. After being returned to the patient’s body, the CTL019 cells proliferate and then eliminate B cells. Moreover, they persist in the circulation, helping to guard against the cancer’s recurrence.
As the CTL019 cells potently attack leukemia cells, they also stimulate an unwanted, toxic immune response called cytokine release syndrome in patients. The care team successfully counteracted these side effects with an immunomodulating drug that had never been used for that purpose before, an approach which now has been adopted widely by cell therapy groups.
In addition, because the CTL019 therapy eliminates healthy B cells along with cancerous B cells, patients must receive infusions of immunoglobin to perform the immune function provided by normal B cells.