A lifesaving cancer therapy could actually be causing new cancers in patients receiving the treatment.

CAR-T therapies have saved tens of thousands of terminally-ill blood cancer patients since 2017, working by extracting immune cells from the body and re-engineering them in a lab — before infusing them back into patients.

But in a letter issued this week, the Food and Drug Administration said the treatment should now carry a black box warning — the most severe safety warning — that they may cause cancer.

The agency highlighted, however, that the benefits of the treatment ‘continue to outweigh the potential risks’.

An illustration of a T cell, blue, attacking a cancer cell, red. This underlines how CAR-T therapies work

An illustration of a T cell, blue, attacking a cancer cell, red. This underlines how CAR-T therapies work

CAR-T therapies, or chimeric antigen receptor T-cell therapies, were first approved in November 2017 and are reserved for cancer patients who would otherwise die without it

CAR-T therapies, or chimeric antigen receptor T-cell therapies, were first approved in November 2017 and are reserved for cancer patients who would otherwise die without it 

They are currently investigating 19 cases of cancer among patients, compared to the 27,000 who have received the treatment — suggesting a risk of cancer of about one in 1,500 patients.

Experts say the breakthrough treatment may cause cancers by disrupting cell DNA which then leads to other cancers.

It is not unheard of for cancer therapies to themselves cause the disease, with this already an established risk for radiation and chemotherapy. 

CAR-T therapy, or chimeric antigen receptor T-cell therapies, involves harvesting white blood cells from a patient and then genetically altering them in a lab to target cancer cells.

These are then infused back into a patient and get to work eliminating the cancer.

The treatment is about 76 percent effective against blood cancers and was first approved in 2017 — with six versions now available.

In its update, the FDA said the black box should now include the following warning on its prescribing information: ‘T cell malignancies have occurred following treatment with BCMA- and CD19- directed genetically modified autologous T cell immunotherapies, including KYMRIAH.’

T cells are a type of white blood cell harnessed by the therapy, with malignancies referring to when these cells turn cancerous.

The letter was updated to the drug-makers: Bristol Myers Squibb, for Abecma and Breyanzi; Gilead Sciences’ Kite Pharma, for Yescarta and Tecartus; Johnson & Johnson’s Carvykti; and Novartis, for Kymriah.

The companies said in statements they have agreed to add black box warnings to their drugs.

A spokeswoman for Novartis told DailyMail.com in a statement: ‘Novartis places the highest priority on patient safety and is committed to fully understanding the effects of its medicines.

‘Novartis will work with the FDA to update the Kymriah prescribing information appropriately in the interest of patients.’

She added: ‘Novartis has not found sufficient evidence to support the causal relationship between Kymriah and secondary T-cell malignancies to date and remains confident in the favorable benefit/risk profile of Kymriah.’

This is the third black box warning to be added to the medications, with the others including cytokine storms — an immune system overreaction that can be fatal — and neurological toxicities.

The cancer warning was already detailed on the prescribing information but was not previously included in the black box. 

The National Cancer Institute estimates there will be roughly 60,000 new cases of leukemia in 2023, resulting in more than 20,000 deaths.

A third of patients with blood cancer die within five years of a diagnosis.

The Leukemia and Lymphoma Society estimates 90,000 people will be diagnosed with lymphoma, a cancer of the lymph system that includes Hodgkin (HL) and Non-Hodgkin (NHL) Lymphoma, and 21,000 are estimated to die from the disease. The five-year survival rate for HL is 96 percent and 85 percent for NHL.

Myeloma, another type of blood cancer, is expected to affect 35,000 people and result in 12,500 deaths. The five-year survival rate is 77 percent. 

What is CAR-T therapy? 

CAR T-cell therapy (or chimeric antigen receptor T-cell therapy) is a form of immunotherapy, using the power of a patient’s immune system to fight the disease.

There are several types that work in different ways to help the immune system recognize and attack cancer cells.

With CAR T-cell therapy, immune cells called T-cells are engineered to seek out and destroy cancer cells.

The process of making these weaponized T-cells is lengthy, complex and expensive.

It begins with hooking the patient up to a machine (similar to a dialysis machine used for kidney patients) that takes a sample of their blood and separates out their T-cells, before returning the rest of the blood to their body.

The machine repeats the process until it has collected 200ml of T-cells, which can take six hours.

In a lab, these T-cells are then engineered to hunt down and destroy the patient’s cancer. This is done using an inactivated virus to insert genetic material instructing the cells to make a protein called a chimeric antigen receptor (CAR) that recognizes a specific protein on the patient’s cancer cells.

Certain cancers over-produce certain proteins and the treatments target these.

The supercharged T-cells are then multiplied in the lab, before an infusion of 200 million cells is delivered to the patient via a drip, which takes just two minutes.

The cells should then home in on, and kill, cancer cells that have the protein they’ve been engineered to recognize. In some cases the cancer is undetectable within a month, although this can take longer.

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