An advisory committee calls on the US Medicines Agency (FDA) to authorize the marketing of gene therapy to treat a severe form of leukemia.
- Acute lymphoblastic leukemia is cancer of the blood and bone marrow that affects blood stem cells.
- In 2012, 810 new cases of ALL were diagnosed in France.
- 44% of diagnoses concerned children under 15 years old.
- In 70 to 90% of cases, complete remission is obtained.
- But 15% of ALL cases are resistant to treatment.
- CTL019 gene therapy teaches the immune system to recognize failing cells and destroy them.
A world first is being prepared in the United States. Gene therapy may soon be approved by the Food and Drug Administration (FDA). Intended to treat acute lymphoblastic leukemia (ALL), it modifies the action of T lymphocytes.
One Consultative Committee experts concluded in favor of bringing this innovative approach to market. While raising reservations about the long-term side effects of such treatment.
If this advice is followed by the health authorities, it would be the first time that such a strategy would be authorized in the country. The gene therapy in question, CTL019, was developed by the University of Pennsylvania (USA) and purchased by the Swiss laboratory Novartis, which now owns the patent.
29 patients in remission
The treatment of acute lymphoblastic leukemia is based on the CAR-T cell technique: the patient’s T lymphocytes are extracted before being genetically reprogrammed in the laboratory, using inactivated HIV.
Once the material of the cells has been changed, they are reinjected into the patients. They then multiply and gradually replace the untreated lymphocytes. At the same time, these enhanced white blood cells attack the failing B cells that cause this cancer of the blood and bone marrow.
In practice, the results delivered by the laboratory are rather conclusive. Of the 63 patients treated between 2015 and 2016, 52 reached the stage of remission. The others are deceased. At the end of November, 29 people were still in remission. 11 relapsed.
Heavy side effects
It is on the basis of these data that the Advisory Committee issued a positive opinion. But not without reservations. Gene therapy should be reserved for young patients with ALL – between 3 and 25 years old – and in treatment failure. No question, given the cumbersome process, to expand access.
The CTL019 gene therapy indeed requires intensive monitoring. This is because modified T lymphocytes not only attack defective B cells, but also those whose functioning is normal. Patients therefore need regular injections of immunoglobulin, as a replacement. And all these treatments have a cost, estimated at 300,000 dollars (263,000 euros).
The side effects of the treatment are also very serious. The first patient, then 6 years old, suffered from a high fever, low blood pressure and pulmonary congestion. Experts are also worried about possible serious long-term side effects, such as cancer induced by gene therapy.
A therapeutic breakthrough
To address these concerns, the clinical trial coordinators scheduled close patient monitoring for 15 years. While waiting for this additional data, the experts of the advisory committee did not hesitate. They unanimously ruled in favor of placing it on the market.
It must be said that the expectations are enormous. About 15% of cases of acute lymphoblastic leukemia are resistant to treatment. This justified, in 2014, obtaining the status of “major therapeutic breakthrough”, accelerating the analysis process by the health authorities.
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