A new genetic modification therapy designed for treating pediatric leukemia is a promising development, said a Catholic bioethicist.

Gene therapies have garnered public attention for their potential medical significance, and because of problematic research procedures surrounding their development and the moral questions they raise.

However, the new treatment, called Kymriah, is a hopeful development and a morally licit use of genetic modifications in medicine, said Fr. Tadeusz Pacholczyk, Ph.D., of the National Catholic Bioethics Center.

Because the therapy only uses matured cells from the patient, Fr. Pacholczyk told CNA, it does not entail the same ethical problems as other forms of gene therapy under investigation – including therapies which destroy human embryos or make modifications of cells which can be passed onto future generations. Instead, developing therapies which make "genetic changes to help our immune system do better what it is supposed to do, namely identifying and eliminating various dangers from the body, is a praiseworthy goal," he said.

"To the extent that side effects can be limited or controlled, the therapy appears to be very promising, with reports of high success rates in slowing or even eliminating certain childhood cancers like pediatric acute lymphoblastic lymphoblastic leukemia," Fr. Pacholczyk said.

Kymriah, developed by drug company Novartis, is a highly personalized form of immunotherapy called CAR T-cell therapy. The procedure, short for "Chimeric Antigen Receptor T-cell Therapy," takes a person's T-cell – a kind of white blood cell – and genetically modifies it to contain a new kind of protein.

This protein, called a chimeric antigen receptor, or CAR, helps detect certain kinds of cancer cells. When the body's T-cells are reintroduced to the body, they are now able to find and kill the cancer cells.

The treatment is specialized to attack a kind of pediatric cancer called acute lymphoblastic lymphoblastic leukemia, or ALL. ALL is a bone marrow and blood cancer, and is one of the most common childhood cancers in the United States – according to the FDA, over 3,000 patients under the age of 20 are diagnosed with it each year.

Kymriah was recently approved by the FDA and will be offered to patients who have not responded to other existing treatments, or those whose cancer has returned after initial treatment. Such patients normally have almost no chance of survival. However, in a clinical trial with Kymriah, the majority of patients who received the treatment saw their cancer go into remission, the FDA said.

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The treatment is not without side effects. Sometimes, when the white blood cells are rewritten, they can lead to a severe immune response called cytokine release syndrome, or CRS, when they are reintroduced. Symptoms of this syndrome can include high fever, flu symptoms, dangerously low blood pressure, and organ damage. It can also cause neurological symptoms, including swelling of the brain, which can be fatal.

In light of these potential side effects, the FDA also approved the expansion of use of an immune suppressing drug for treatment for CRS. The drug has shown to be an effective treatment for CRS after treatment with CAR-T cells. The FDA will also require Novartis to continue monitoring Kymriah after its release for long-term side effects and other harmful side effects.

Fr. Pacholczyk said that when considering the treatment for any specific situation, it is important to weigh "the question of whether the risks may be greater than the benefits."

But with the control of the dangerous side effects, and taking into account the risks of the treatment, the new gene therapy looks "promising," he said.