Scientists identify cancer kill ‘switch’ that destroys tumours from the inside out

A ‘kill switch’ that causes the death of cancer cells could pave the way for new treatments, scientists say.

American researchers have discovered a segment of a protein on the outside of tumor cells that causes them to self-destruct when activated.

Experts say the findings not only open the door to new drugs in the fight against cancer, but could also allow doctors to boost existing therapies.

For example, it could allow CAR T-cell therapy to eventually fight solid tumors such as those of the breast, lung and prostate.

The groundbreaking therapy involves giving cancer patients specially developed T cells to detect and destroy tumors.

American researchers, conducting laboratory tests, discovered a segment of a protein on the outside of cancer cells that causes the cells to self-destruct when activated. Pictured: Image of white blood cells attacking cancer cells

But it fights solid tumors because the immune cells – which are infused into patients – “simply cannot penetrate the microenvironment to produce a therapeutic effect,” says Dr Jogender Tushir-Singh of the University of California, Davis.

CD95 receptors, also known as Fas receptors, are located on the outside of the membranes of cancer cells.

When activated, they release a signal that causes the cell to self-destruct.

Although scientists have long known about the existence of these receptors, attempts to induce them have been unsuccessful.

Researchers at the UC Davis Comprehensive Cancer Center have identified a portion of the receptor that can trigger the destruction process when targeted.

The results of their laboratory experiments with cells and mice were published in the journal Cell death and differentiation.

Dr. Tushir-Singh, one of the researchers, said: ‘Now that we have identified this epitope, there could be a therapeutic pathway to target Fas in tumors.’

Currently, surgery, chemotherapy and radiotherapy are still the standard of care for cancer patients.

However, some children with leukemia and adults with lymphoma may receive chimeric antigen receptor (CAR) T-cell therapy.

It involves collecting and altering their own T cells, which are responsible for fighting infections and disease but struggle to detect cancer cells.

Tweaked cells are returned to the bloodstream via an infusion. The CAR T cells are then theoretically trained to recognize and attack cancer cells.

Although this treatment is effective against blood cancer, a minority of patients will see the cancer return. And it is not yet available for patients with solid tumors.

Dr. Tushir Singh says a treatment that targets the ‘switch’ to kill cancer could theoretically destroy any remaining cancer cells after CAR T-cell therapy.

This would “provide a potential one-two punch against tumors.”

He said it could also potentially support CAR T-cell therapy in solid tumors, but did not specify how this would work.

The study also suggests that cancer patients with a mutated epitope on their CD95 receptor may not respond to CAR-T therapy at all.

Dr. Tushir-Singh said mutations in this epitope could be used as a marker to determine who should receive CAR T-cell therapy.

The researchers now plan to design a new class of antibodies that can bind to and activate this kill switch.

However, it is unclear whether this treatment will work and, if so, which cancers it could eradicate.

And it takes years before new therapies are available to patients because they need to be thoroughly tested.