Pioneering gene therapy approved for leukaemia in the US

A CAR-T treatment – a type of gene therapy for cancer – has been approved for use in the US. Announced by the US Food and Drug Administration (FDA) on Wednesday, this is the first approval anywhere in the world for a type of CAR-T therapy, although the techniques have been used experimentally for some time.

CAR-T therapy made headlines earlier this year, when it was announced a CAR-T approach had saved the life of Layla, a young child in the UK who had leukaemia. The approach involves reprogramming a person’s own immune cells to make them better at targeting cancerous ones.

The drug that has been approved by the FDA is Kymriah, a treatment for B-cell acute lymphoblastic leukaemia, the most common childhood cancer in the US.

To synthesise Kymriah, a patient first has a type of immune cell, called T-cells, removed from their body and transported to a facility in New Jersey operated by the pharmaceutical firm Novartis. Here, viruses will be used to insert a gene into these cells. The gene codes for a protein called a chimeric antigen receptor (CAR).

These cells are then reinfused back into the person. The added protein helps these modified T-cells home in on and fight leukemia cells.

In a trial, this approach achieved an 83 per cent remission rate over a period of three months in people who hadn’t responded to other treatment options. The FDA has approved Kymriah for people aged 25 or under who have not responded to other treatments, or who have relapsed.

One-off treatment

Nearly half the people in the trial experienced a side effect caused by an unwanted immune response triggered by the altered T-cells. Because of this, the FDA is requiring staff at the 32 facilities approved for this treatment to undergo specific training to recognise this response, called cytokine release syndrome.

Kymriah will cost $475,000. This sounds high, but it’s lower than some analysts expected, and unlike many expensive cancer drugs, it is a one-off treatment that could result in years, not months, of extended lifespan.

The FDA’s decision has been hailed as the first approval for a gene therapy in the US. Some argue that this isn’t a true gene therapy, as the genes introduced into the T-cells are not the treatment themselves – it is the transformed T-cells that go on to fight the cancer. But the FDA defines human gene therapy as products that introduce genetic material into a person’s DNA to treat a disease, so has classified Kymriah as such.

Europe has already approved two gene therapies for inherited diseases, while China approved a gene therapy for cancer treatment in 2004.

As for CAR-T therapies, other firms have similar treatments in the works, while Novartis also plans to get Kymriah approved for treating lymphoma.