TY - JOUR AB - Targeting inhibitory immune checkpoint molecules has significantly altered cancer treatment regimens. T cell immunoglobulin and mucin domain 3 (TIM3) is one of the major inhibitory immune checkpoints expressed on T cells. Blocking the engagement of TIM3 and its inhibitory ligand galectin‑9 may potentiate the effects of immunotherapy or overcome the adaptive resistance to the therapeutic blockade of programmed cell death protein 1, cytotoxic T‑lymphocyte‑associated protein 4, B‑ and T‑lymphocyte attenuator and lymphocyte‑activation gene 3, amongst others, as each of these immune checkpoints harbors unique properties that set it apart from the rest. Heavy chain variable fragment (VH)‑derived single‑domain antibodies (sdAbs) represent a class of expanding drug candidates. These sdAbs have unique advantages, including their minimal size in the antibody class, ease of expression, broad scope for modular structure design and re‑engineering, and excellent tumor penetration. In the present study, two sdAbs, TIM3‑R23 and TIM3‑R53, were generated by immunizing rabbits with the recombinant extracellular domain of TIM3 and applying phage display technology. These sdAbs were easily expressed in mammalian cells. The purified sdAbs were able to bind to both recombinant and cell surface TIM3, and blocked it from binding to the ligand galectin‑9. In vivo studies demonstrated that TIM3‑R53 was able to potentiate the antitumor activity of chimeric antigen receptor T cells that targeted mesothelin. In conclusion, the results of the present study suggested that TIM3‑R53 may be a novel and attractive immune checkpoint inhibitor against TIM3, which is worthy of further investigation. AD - College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P.R. China Clinical Testing Branch, Hongshan District Chinese Medicine Hospital, Wuhan, Hubei 430000, P.R. China Department of Internal Medicine‑Oncology, Hubei Cancer Hospital, Wuhan, Hubei 430079, P.R. China Clinical Laboratory, Hospital of Huazhong Agricultural University, Wuhan, Hubei 430070, P.R. China AU - Yang,Liu AU - Chen,Xin AU - Wang,Qian AU - Zhu,Yuankui AU - Wu,Changfa AU - Ma,Xuqian  AU - Zuo,Dianbao AU - He,Huixia AU - Huang,Le AU - Li,Jingwen AU - Xia,Chunjiao  AU - Hu,Sheng AU - Yang,Xiaoqing AU - Feng,Mingqian DA - 2021/07/01 DO - 10.3892/ol.2021.12803 IS - 1 JO - Oncol Lett KW - T cell immunoglobulin and mucin domain 3 galectin‑9 single‑domain antibody chimeric antigen receptor T cells PY - 2021 SN - 1792-1074 1792-1082 SP - 542 ST - Generation of TIM3 inhibitory single‑domain antibodies to boost the antitumor activity of chimeric antigen receptor T cells T2 - Oncology Letters TI - Generation of TIM3 inhibitory single‑domain antibodies to boost the antitumor activity of chimeric antigen receptor T cells UR - https://doi.org/10.3892/ol.2021.12803 VL - 22 ER -