This year, gene therapy finally became a clinical reality. The U.S. Food and Drug Administration approved two personalized treatments that engineer a patient’s own immune system to hunt down and kill cancer cells. The treatments, the first gene therapies ever approved by the FDA, work in people with certain blood cancers, even patients whose cancers haven’t responded to other treatments.
Called CAR-T cell immunotherapy (for chimeric antigen receptor T cell), one is for kids and young adults with B cell acute lymphoblastic leukemia, or ALL, approved in August (SN Online: 8/30/17). The other is for adults with non-Hodgkin lymphoma, approved in October. Other CAR-T cell therapies are in testing, including a treatment for multiple myeloma.
“It’s a completely different way of treating cancer,” says pediatric oncologist Stephan Grupp, who directs the Cancer Immunotherapy Program at the Children’s Hospital of Philadelphia. Grupp spearheaded the clinical trials of the newly approved ALL therapy, called Kymriah.
Researchers are developing many different versions of CAR-T cell therapies, but the basic premise is the same: Doctors remove a patient’s T cells (immune system cells that attack invaders) from a blood sample and genetically modify them to produce artificial proteins on their surfaces. Those proteins, called chimeric antigen receptors, recognize the cancer cells in the patient’s body. After the modified T cells make many copies of themselves in the lab, they’re unleashed in the patient’s bloodstream to find and kill cancer cells.
CAR-T cell therapy is particularly exciting because it works well in people whose cancers haven’t responded to other available treatments, says Renier Brentjens, an oncologist at Memorial Sloan Kettering Cancer Center in New York City. Of the 63 kids and young adults treated in a clinical trial of Kymriah, 83 percent had their cancers go into remission within three months.
Now that these therapies have been clinically approved, there’s been an “explosion of interest” in the approach, says Dario Campano, an immunopathologist at the National University Cancer Institute in Singapore. Going forward, he expects to see even more rapid progress in the technology. Fifteen years ago, Campana helped develop the chimeric antigen receptor that’s used in Kymriah today. For now, the treatments are approved for use only when other treatments have failed, but someday CAR-T cell therapy could be the first treatment doctors try, he says.
One drawback is the price. Kymriah costs $475,000 for a onetime treatment, according to Novartis, which makes Kymriah. The non-Hodgkin lymphoma treatment made by Gilead Sciences, called Yescarta, is listed at $373,000. The total price tag for treatment could be higher when the costs of dealing with side effects and complications are factored in.
The approach is approved only for blood cancers. Using CAR-T cell therapy on solid tumors will require finding ways to get the T cells past additional cellular roadblocks, Grupp says.