Biotechnology · Immunotherapy

Scientists found a hidden T-cell "brake" called SLAMF6, and antibodies that release it

Canadian scientists identified SLAMF6, an internal "brake" that exhausts cancer-fighting T cells on its own, and built antibodies to release it, boosting tumor attacks in mice.

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Evidence certainty

Not AssessableStudy type not set · Rule v2.0

Rests on a source Lumen does not treat as evidence (a press release or unreviewed assertion). Recorded as an unverified claim; supports no reliance.

The five checks

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Source tier

Peer-reviewed · Nature / Montreal Clinical Research Institute (IRCM), Université de Montréal

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Study type

Phase 1

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Sample size (n)

Not applicable by design. Not reported

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Effect size (absolute)

Newly developed blocking antibodies increased human T-cell activation, raised resilient (stem-like) T-cell numbers, reduced exhausted T cells, and drove strong anti-tumor responses in mice, outperforming prior SLAMF6-targeting tools (study reports directional results; an earlier agonist antibody reduced SLAMF6–SLAMF6 energy transfer by ~60% in assays)

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Disease burden

Immune checkpoint inhibitors fail or lose effect in a large share of treated patients; cancer remains a leading cause of death worldwide (~10 million deaths/year)

Primary source: Nature / Montreal Clinical Research Institute (IRCM), Université de Montréal.View primary source Read the Lumen Standard

Peer-reviewedBy Nathan Stanley Martanegara12 June 20261 min read

SLAMF6 acts as a self-triggered brake on the very T cells most able to recover after treatment.

Why it matters: Today's leading immunotherapies (PD-1, PD-L1 inhibitors) release brakes that tumors impose on the immune system, but many patients don't respond or stop responding. SLAMF6 is a different kind of brake: it self-activates on the T cell without any signal from the tumor, which may explain some of those failures.

Cancer researchers have identified a previously unrecognized "brake" inside the immune system that may explain why some treatments stop working, and developed antibodies to release it.

The molecule, SLAMF6, sits on the surface of T cells. Unlike the targets of current immunotherapies, it doesn't need to interact with a tumor to suppress the immune response. Instead, it self-activates directly on the T cell surface, sending a stop signal, and it does so on exactly the population of "stem-like" exhausted T cells that retain the ability to bounce back after treatment.

A team led by André Veillette at the Université de Montréal–affiliated Montreal Clinical Research Institute (IRCM) developed monoclonal antibodies designed to stop SLAMF6 from binding to copies of itself. In lab and mouse experiments, the antibodies produced more activation of human T cells, higher numbers of resilient immune cells, fewer exhausted cells, and strong anti-tumor responses.

The researchers say the new antibodies outperform any existing tool aimed at SLAMF6, and could form the basis of a new class of immunotherapy, potentially for patients who no longer benefit from PD-1 or PD-L1 drugs, used alone or in combination. The next step is early-phase clinical trials in people with solid tumors or blood cancers.

“"By identifying an internal brake that had until now gone unrecognized and developing antibodies capable of neutralizing it, our researchers are offering an innovative solution to the limitations of current treatments."”
André Veillette · Director, Molecular Oncology Research Unit, and Professor of Medicine · Montreal Clinical Research Institute (IRCM) / Université de Montréal

Source: Nature / Montreal Clinical Research Institute (IRCM), Université de Montréal · Nathan Stanley Martanegara · 12 June 2026