TIM-3 as a therapeutic target in anaplastic thyroid carcinoma: Preclinical and transcriptomic evidence supporting a new immunotherapy avenue.

We recently characterized the microenvironment of Anaplastic Thyroid Carcinoma (ATC) as immune-exhausted, rich in TIM-3-expressing exhausted cytotoxic T lymphocytes (CTLs). PD-1 was notably the least frequently expressed immune checkpoint (ICP). The results provided a potential explanation for the limited efficacy of anti-PD-1/PD-L1 immunotherapy, highlighting TIM-3 as another promising target. This pilot study further evaluated the potential efficacy of targeting TIM-3 in ATC as a therapeutic strategy in an in vitro model. A co-culture model of ATC cell line 8505C with exhausted TIM-3+ve/PD-1+ve CTLs was established and treated with anti-TIM-3 and anti-PD-1 antibodies, alone and in combination. Antibody efficacy was evaluated using flow cytometry, measuring Granzyme B and Perforin for CTL cytotoxic activity, and Annexin V and propidium iodide for tumor cell death. Additionally, differential gene expression before and after ICP blockade was analyzed using the NanoString nCounter Immune-oncology panel. Both individual and combined antibody treatments enhanced CTL cytotoxicity and promoted tumor cell death. Interestingly, ICP inhibition induced an upregulation of immune-activating pathways and downregulation of genes associated with tumor progression. These findings support the potential of TIM-3 blockers as an alternative to or in combination with anti-PD-1 therapy, thereby providing a rationale for further clinical investigation.