Today, August 30, 2017, the U.S. Food and Drug Administration approved a revolutionary, first-in-class cancer immunotherapy for children and young adults with relapsed or refractory B-cell acute lymphoblastic leukemia (B-ALL). Referred to as a “living drug,” tisagenlecleucel (KymriahTM, Novartis) uses a patient’s own T cells. After extracting them and enabling them—through genetic modification—to more effectively eliminate cancer cells, the enhanced T cells are then re-infused back into the patient. In this case, the young patients’ T cells are equipped with CARs (chimeric antigen receptors) that target the CD19 protein found on cancerous B cells.
The CAR T cell immunotherapy’s approval comes a month and a half after the treatment was unanimously backed by the FDA’s Oncologic Drugs Advisory Committee, bolstered by an 83% overall remission rate in the pivotal phase II ELIANA study (NCT02435849). In other words, 83% of the patients experienced a complete response that eliminated all signs of their disease, although some patients exhibited an incomplete blood count recovery. All of these responses occurred within three months of treatment and, importantly, none of these patients showed evidence of minimal residual disease (MRD), a potential indicator of future relapse.
Other clinical studies, while not cited in the official approval, have also lent support to the efficacy of this anti-CD19 CAR T cell immunotherapy approach for children with leukemia. In the B2101J study, 95% of pediatric B-ALL patients had complete responses, many of which were durable, while 89% showed no evidence of MRD.
The Cancer Research Institute’s Carl H. June, M.D., is one of the pioneers of this unique immunotherapy approach, which first began to garner attention in 2012 after being used to successfully treat Emily Whitehead (pictured below with Dr. June), who had previously failed multiple rounds of chemotherapy but has now been in remission for over 5 years. With this approval, many more children and young adults will hopefully be able to overcome their leukemia, especially those with aggressive forms that don’t respond to chemotherapy and stem cell transplants.
CAR T cells have also been effective for adult patients with leukemia, and have demonstrated promising potential in lymphoma patients. Challenges still remain when it comes to treating solid cancers (as opposed to blood cancers) with CAR T cell immunotherapy. Fortunately, these challenges are being addressed—by CRI scientists such as Stanley R. Riddell, M.D., and Michel Sadelain, M.D.,Ph.D., among others—and have resulted in progress against certain tumor types, providing hope that this amazing technology may be able to help even more patients in the near future.