Tumors block the recruitment of activated "tumor-killing" T cells

T cells, the cells of our immune system that can kill the tumor, barely infiltrate the tumor. What halts T cell infiltration is far from being understood. Researchers of the de Duve Institute have discovered a novel mechanism by which tumor cells reduce T cell infiltration. The study, which was led by Monica Gordon-Alonso and Pierre van der Bruggen of the de Duve Institute and the Brussels Branch of the Ludwig Institute for Cancer Research, details how massive secretion of galectin by the tumor hijacks some essential immune signals within the tumor microenvironment. Retention of these immune signals blocks important steps of the immune response, in particular the recruitment of activated "tumor-killing" T cells inside the tumor. The researchers demonstrated in tumor-bearing mice that galectin-trapped immune signals are released upon treatment with galectin antagonists, resulting in more T cell infiltration and delayed tumor growth.

This study suggests therefore that drugs that counter galectin may potently boost the efficiency of cancer immunotherapies by two different mechanisms: an increase in T cell infiltration inside tumor masses and a re-activation of lethargic T cells, as shown before by the same research group.

Article describing this research

Galectin-3 captures interferon-gamma in the tumor matrix reducing chemokine gradient production and T-cell tumor infiltration

Gordon-Alonso Monica, Hirsch Thibault, Wildmann Claude, van der Bruggen P.

Nature Communications. 2017; doi: 10.1038/s41467-017-00925-6