AINEWS
Researchers map a self-activating brake on T cells, separate from PD-1
A receptor called SLAMF6 sits on the T cell itself and acts as a brake independent of the PD 1/PD L1 axis, offering a candidate target for treatment resistant disease.
A receptor called SLAMF6 sits on the T cell itself and acts as a brake independent of the PD 1/PD L1 axis, offering a candidate target for treatment resistant disease.
The most successful modern cancer drugs work by releasing a brake on the immune system: the checkpoint inhibitors that block PD-1 or its partner PD-L1. For a meaningful share of patients, that brake is not the only one holding the immune response back. In work described by a Université de Montréal team this week, a second, structurally different brake has been mapped. It lives on the T cell itself, on a receptor called SLAMF6, and it can switch itself on without needing a signal from the tumor.
The finding, published in Nature (2026 Apr;652(8110):722-730) by Dr. André Veillette and colleagues at Université de Montréal and the Montreal Clinical Research Institute, points to a candidate target for the next generation of immunotherapies aimed at patients whose tumors do not respond to, or eventually escape, today's checkpoint drugs.
SLAMF6 belongs to the SLAM family of receptors, a separate signaling system from the PD-1 axis that current immunotherapies target. In mouse cancer models, Veillette and colleagues showed that monoclonal antibodies blocking SLAMF6 restored T cell activation and improved tumor control. The mechanism is mechanistically distinct from PD-1/PD-L1 blockade: SLAMF6 acts on the T cell directly, triggered in cis by homotypic interactions at the T cell surface, without requiring a partner molecule on the tumor surface.
The clinical problem the work is trying to address is well known to oncologists. PD-1 and PD-L1 inhibitors have transformed care for melanoma, lung cancer, kidney cancer, and others, but resistance is common. Some patients never respond. Others respond and then relapse. The field has spent years mapping escape routes, with candidates including LAG-3, TIM-3, and TIGIT, several of which are now in late-stage clinical testing.
Veillette's group is arguing that SLAMF6 is a different kind of escape route. PD-1 and its peers are activated by ligands produced by the tumor or its surroundings. The researchers argue that SLAMF6 appears to be self-activating: a brake that the T cell can engage from within, independent of what the tumor is doing. That distinction is what makes it worth its own drug-development program, the researchers say.
The evidence, for now, is preclinical. The work describes mouse experiments, not human trials, and there is no public timeline for a clinical candidate. The team has not disclosed a biotech partner or an investigational therapy in patients. Framing this as a near-term treatment for resistant disease would overstate the data. What the work does is sharpen the map of where the immune system can be re-engaged when PD-1/PD-L1 blockade is not enough. It gives drug developers a named, structurally novel target to test next.
The check that matters now is whether the mouse biology holds up in human tumors, and whether blocking SLAMF6, alone or in combination with PD-1 inhibitors, can move the needle on cancers that have stopped responding to existing therapy. The first answers will come from preclinical work in human tumor samples and, eventually, careful early-phase trials. Until then, SLAMF6 is a new entry on a growing list of immune brakes, and one that researchers who study resistance will be watching closely.