Dear Doctor: Our daughter was successfully treated for leukemia as a child, but the chemotherapy she went through was pretty brutal. Now I've read that we have the first gene therapy for cancer, which is a huge deal. How does it work? How much does it cost? Are there side effects?
Dear Reader: We're so glad that your daughter's treatment was successful. As you mention, the therapies we currently rely on can take a steep physical toll. That's part of what makes new breakthroughs in precision medicine -- which includes targeted therapy, immunotherapy and gene therapy -- so promising and so exciting.
Before we get into the details of Kymriah, the name of the treatment you're writing about, it's important to note that gene therapy is still new and evolving. It's quite expensive, it doesn't help every person every time, and it can have side effects that range from challenging to life-threatening.
Kymriah is the first gene therapy to be approved by the Food and Drug Administration. It targets B-cell acute lymphoblastic leukemia, a cancer of the blood and bone marrow that affects children and young adults. The therapy, which received FDA approval in August 2017, was developed at the University of Pennsylvania, and is licensed by the drug company Novartis.
The therapy works by altering the genetic code within a patient's own T cells, which are part of the immune system. The T cells are extracted from the patient, frozen and then shipped to a Novartis lab in New Jersey. There, the patient's cells are reprogrammed to seek out and destroy the leukemia cells. They do this by targeting a specific protein that is unique to the leukemia cells.
When the rewired T cells are returned to the patient's body, they don't only attack the cancer, but they also multiply in number. According to the university's scientists, a single engineered cell can generate 10,000 new cells, and can survive in the body for years. This benefits patients with refractory leukemia, which is when leukemia cells persist in the body even after intensive treatment.
Side effects of Kymriah can be severe. It's possible that the altered T cells will set off a positive feedback loop within the immune system, known as a cytokine cascade. Symptoms include high fever, severe fatigue, rash, lung congestion, neurological issues and a dangerous drop in blood pressure. In some cases, these can lead to death. Because of this, Kymriah therapy may only take place at designated treatment centers, which are equipped to deal with these side effects.
Customizing each individual patient's cells is expensive. At this time, treatment with Kymriah runs about $475,000. Novartis has said it won't charge patients who don't respond to the drug within a month of treatment. Some types of financial aid are also available.
If turning your own cells into a successful cancer drug sounds hard to believe, you're not alone. When the first patient treated with Kymriah in 2010 was shown to be cancer-free a month later, even the lead scientists who developed the drug had trouble accepting it. They ordered a follow-up biopsy just to be sure.
Meanwhile, the research continues. The hope is that, with FDA approval of the first gene therapy, advancing and refining the science can move forward even more rapidly.
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