The invention discloses application of timosaponin AIII in preparation of a
curative effect enhancer for CAR-
T cell therapy and a product for overcoming
drug resistance. The invention proves that TAIII is an allosteric inhibitor of an
adenosine A2A
receptor, and blocks a downstream
signal channel through allosteric combination with A2AR, so that expression of a
transcription factor FoxP3 is inhibited, Tregs in a CAR-T product is selectively cleared,
immunosuppression of the Tregs on
effector T cells is relieved, meanwhile, the proportion of central memory T cells is increased, and amplification, durability and
cytokine secretion functions of the CAR-T cells are enhanced. The invention further provides a CAR-
T cell composition containing the TAIII, and the TAIII and the CAR-T cells are combined or used as a pretreatment agent, so that the
tumor removal capability can be remarkably enhanced, and recurrence
after treatment can be effectively prevented. The invention provides a safe and effective new strategy for enhancing the anti-tumor activity of the CAR-T cells and overcoming the
drug resistance of the CAR-T therapy.