The US Food and Drug Administration (FDA) on Wednesday approved a "historic" treatment that genetically engineers a patient's own immune cells to fight childhood leukemia.

The procedure, known as CAR-T cell therapy, takes a patient's immune cells, or T-cells and white blood cells, and genetically modifies them to give a power boost to viciously target leukemia.

Once transfused back into the patient, the immune cells then attack leukemia cells for months or even years.

"We're entering a new frontier in medical innovation with the ability to reprogram a patient's own cells to attack a deadly cancer," said FDA Commissioner Scott Gottlieb. "New technologies such as gene and cell therapies hold out the potential to transform medicine and create an inflection point in our ability to treat and even cure many intractable illnesses."

Read more: Fighting cancer with methadone - making chemotherapy more powerful

Last resort

The treatment was developed by Novartis Pharmaceuticals and the drug is known as Kymriah (tisagenlecleucel).

The immune system-altering treatment was approved for patients aged 3 to 25 with a blood cancer called acute lymphoblastic leukemia (ALL), the most common form of childhood cancer in the US.

About 3,100 people under the age of 20 are diagnosed with ALL each year in the United States. Around 20 percent of those with ALL fail to respond to traditional drug, bone marrow transplants and chemotherapy treatments. Typically, young patients with ALL who fail chemotherapy have only a 30 percent chance of survival.

The breakthrough treatment would only be used if the disease failed to respond to standard treatment.

The therapy would cost $475,000 (400,000 euros) per dose, but Novartis said anyone who didn't respond within a month would not have to pay. Typical treatments of ALL, such as bone marrow transplants, can run up to $800,000 in the first year.

Application to be filed in EU

According to studies, about 83 percent of patients responded to CAR-T cell therapy went into remission after three months.

The treatment does carry potential side effects, including an immune overreaction, fever, high blood pressure, neurological reactions, acute kidney injury and decreased oxygen.

Questions also remain about the drug's possible long-term side effects and ability to prevent ALL from coming back.

Due to their age, many of those suffering from the disease would be covered by their parent's health insurance or Medicare in the US.

The procedure is best known for treating a now 12-year-old girl named Emily Whitehead, who has been cancer-free for five years after being the first child to receive the experimental therapy.

An application for CAR-T is expected to be filed with the European Medicines Agency by the end of the year.

cw/cmk (AP, AFP)