US regulators on Wednesday approved the first gene therapy against cancer - a treatment that uses a patient's own immune cells to fight leukemia - opening a new era in the fight against one of the world's top killers.

The treatment is made by Novartis and is called Kymriah (tisagenlecleucel).

This type of anti-cancer immunotherapy, known as a CAR-T cell therapy, was known by CTL019 until now.

"This marks the first-ever CAR-T cell therapy to be approved anywhere in the world," Novartis CEO Joseph Jimenez told reporters on a conference call.

"It uses a new approach that is wholly personalized by using a patient's own T-cells."

Kymriah was approved by the US Food and Drug Administration for children and young adult patients up to age 25 with a form of acute lymphoblastic leukemia (ALL).