Researchers studying cancer immunotherapy have uncovered an important reason why some treatments stop working for certain patients.
A team led by Dr. André Veillette at the Université de Montréal has identified a molecule called SLAMF6 that acts like an internal brake on the immune system, preventing immune cells from fully attacking cancer.
Their findings, published in the journal Nature, could lead to new therapies for patients who no longer respond to current treatments.
Immunotherapy works by helping the body’s own immune system recognize and destroy cancer cells.
One of the key players in this process is the T cell, a type of white blood cell that can identify and kill abnormal cells.
Many modern cancer drugs, such as PD-1 or PD-L1 inhibitors, are designed to remove the signals that tumors use to hide from T cells.
While these treatments have helped many patients, a significant number either do not respond or eventually relapse.
The new research suggests that part of the problem may lie inside the immune cells themselves. The scientists found that SLAMF6 sits on the surface of T cells and can send a “stop” signal that weakens their ability to fight cancer.
Unlike other inhibitory molecules, this one does not need to interact with tumor cells to have an effect. Instead, it activates itself, reducing the strength of the immune attack and speeding up a process called immune exhaustion, where T cells become worn out and ineffective.
To overcome this obstacle, the research team developed specialized antibodies designed to block SLAMF6 from activating itself.
In laboratory experiments and tests in mice, these antibodies restored the power of T cells. The treated immune cells became more active, produced stronger long-lasting responses, and showed fewer signs of exhaustion. The mice also experienced stronger anti-tumor effects.
Scientists believe this approach could represent a new generation of immunotherapy. It may be especially useful for patients whose cancers have stopped responding to existing treatments. The new antibodies could potentially be used alone or combined with current therapies to enhance their effectiveness.
Before the treatment can be tested in people, researchers plan to conduct early clinical trials to evaluate safety and effectiveness in patients with both solid tumors and blood cancers. Experts say the discovery opens a promising new direction in the fight against cancer because it targets an internal immune barrier that had previously gone unnoticed.
The findings highlight how complex the immune system is and why cancer treatment can be so challenging. By identifying this hidden “off switch” inside T cells, scientists hope to develop therapies that keep the immune system active for longer periods, improving survival and quality of life for patients.
While more research is needed, the study offers new hope that future immunotherapies could help people who currently have limited options, bringing medicine one step closer to more effective and personalized cancer care.
