The claim: immunotherapy has a second brake nobody was targeting. The catch: so far it has only been shown in mice.
Dr. André Veillette of the Université de Montréal, working at the Montreal Clinical Research Institute (IRCM), reported in Nature that a molecule called SLAMF6 acts as a built-in shutoff switch on T cells. The paper, “SLAMF6 as a drug-targetable suppressor of T cell immunity against cancer,” carries a date of 11 February 2026 and lists Bin Li, Ming-Chao Zhong, Cristian Camilo Galindo, Jiayu Dou, Jin Qian, Zhenghai Tang and Dominique Davidson as co-authors.
The mechanics here
Existing drugs such as PD1 and PDL1 inhibitors take away external brakes that tumors impose. Many patients either never respond or stop responding. Veillette’s team found a brake of a different kind. SLAMF6 does not need tumor cells at all. It self-activates on the T cell surface and sends a stop signal that cuts the production of healthy, long-lasting T cells and speeds up exhaustion, the point at which T cells no longer work against cancer.
In other words, a tumor can be stripped of its own defenses and the T cells may still slow down, because the restraint comes from inside.
The fix, and its limits
The team developed monoclonal antibodies that stop SLAMF6 from interacting with itself. In mice, the antibodies produced higher numbers of resilient immune cells and strong anti-tumor responses. The researchers say the antibodies beat all existing strategies aimed at SLAMF6, which makes them candidates for a new class of immunotherapies. They could be used alone or with other immune-based treatments, and may suit patients who no longer benefit from PD1 or PDL1 inhibitors.
Nobody has run these antibodies in a person. The next step is early-phase clinical trials to assess safety and effectiveness in patients with solid tumors or blood cancers.
The institute’s leadership was less guarded. “The discovery made by Dr. Veillette’s team opens the door to a new chapter in immunotherapy,” said IRCM president and scientific director Dr. Jean-François Côté. “Our researchers are offering an innovative solution to the limitations of current treatments,” he said.
Funding came from the Canadian Institutes of Health Research, the Terry Fox Research Institute, BioCanRx, Québec’s Ministry of Economy, Innovation and Energy, and the Canadian Foundation for Innovation.
