This procedure, known as Kymriah (tisagenlecleucel), works to combat acute lymphoblastic leukemia (ALL), the most common childhood cancer in the US with over 3,000 new cases diagnosed every year. Kymriah extracts a patient's autologous T-cells and sends them to a facility, where they are modified to include a new gene that directs the T-cells to target particular leukemia cells. Then the genetically-modified cells are sent back to be re-inserted in the patient.

"Kymriah is a first-of-its-kind treatment approach that fills an important unmet need for children and young adults with this serious disease," said Peter Marks, M.D., Ph.D., director of the FDA's Center for Biologics Evaluation and Research (CBER), in the FDA's post. "Not only does Kymriah provide these patients with a new treatment option where very limited options existed, but a treatment option that has shown promising remission and survival rates in clinical trials."

One study cited in the FDA's announcement treated 63 children and young adult patients with Kymriah, which saw an 83 percent remission rate after three months. The agency granted approval of the gene therapy to Novartis Pharmaceuticals Corp.