First reprogrammed-cell leukaemia therapy approved

Novartis, the pharma multinational headquartered in Switzerland, has successfully sought approval for a new class of therapy that uses a patient's own blood cells to combat cancer.

This week the US FDA (Food and Drug Administration) gave the go ahead for patients to be treated with the agent, generically named tisagenlecleucel and marketed as "Kymriah".

The treatment is intended to help children and young adults with a blood cancer called acute lymphoblastic leukaemia. This is one of the leading causes of childhood cancer, accounting for 25% of malignancies in this age group and is, thankfully, often curable. But about 20% of patients do not respond to existing therapies, and for them the prognosis was previously grim.

Now, a recent trial has shown that over 80% of those treatment failures can also be cured using Kymriah.

The treatment involves first extracting a sample of the patient's blood and extracting blood cells called T lymphocyte. These cells are naturally equipped with cell-killing machinery. In the laboratory, these cells are "weaponised" by adding a gene containing the instructions for assembling a structure called a chimeric antigen receptor or CAR. This recognises a specific marker expressed only by the patient's cancer cells and not by healthy tissue. 

These modified killing machines are then reinfused into the patient where they patrol the bloodstream seeking out and destroying the rogue leukaemia cells.

Within 3 months, almost all of the patients who received the therapy, having previously failed to respond to treatment or had suffered a relapse, were in remission.

There were, of course, side effects from the therapy. The most serious was a condition called cytokine release syndrome, which is caused by over-stimulation of the immune system as it goes to war against the tumour cells. About half of the patients in the study developed this problem, which causes fevers, rigors and flu-like symptoms and, in more severe cases, delirium and confusion. However, it can be controlled with existing drugs and can be regarded as a sign that the therapy is working.

There is also another unpleasant side effect: the eye-watering price. Novartis have pegged the cost of a course of treatment for those in whom it succeeds at nearly half a million US Dollars, which has led some patient groups to describe drug pricing as "fundamentally broken".