Liothyronine (Tresitope) is an active form of thyroid hormone, binding to β1 thyroid hormone receptor (TRβ1), and activates its activity.

METHODS: Mouse colon adenocarcinoma cells MC38 were treated with Liothyronine (12.5-100 µM) for 24-72 h. Cell viability was measured using MTT Assay.
RESULTS: Liothyronine did not affect the cell viability of MC38 cells at the concentrations tested. [1]
METHODS: Jurkat hTIGIT cells were stimulated with anti-CD3 and anti-CD28 stimulatory antibodies and treated with anti-TIGIT (1 µg/mL) and Liothyronine (100 µM) for 48 h. The frequency of IL-2 secreting Jurkat hTIGIT was detected using Flow cytometry.
RESULTS: TIGIT/PVR interaction significantly inhibited IL-2 secretion from Jurkat hTIGIT cells, and the inhibition was significantly reversed by a functional anti-TIGIT antibody and Liothyronine, which has the typical characteristics of an immune checkpoint blocker. [1]

METHODS: To detect anti-tumor activity in vivo, Liothyronine (1.5-5 mg/kg, normal saline with 3% DMSO and 0.5% Tween-80) was injected intraperitoneally every two days for two weeks into C57BL/6 mice bearing MC38 tumors.
RESULTS: Both low and high doses of Liothyronine significantly inhibited the growth of MC38 tumors. Liothyronine significantly increased the frequency of tumor-infiltrating CD8+ T cells and significantly enhanced the secretion of IFN-γ by tumor-infiltrating CD4+ T cells treated with high doses of Liothyronine. [1]