“Advances in chimeric antigen receptor (CAR)-T cell therapy have significantly improved clinical outcomes of patients with relapsed or refractory hematologic malignancies. However, progress is still hindered as clinical benefit is only available for a fraction of patients. In this review, we discuss the reasons why CAR-T immunotherapy fails in clinical practice and what this field has learned since the milestone of single-cell sequencing technologies. Expert xx established the xx system/explored the xx topic/verified the xx conjecture, which provides solutions to solve xx problems/open up a new direction for xx research/lay a foundation for the construction of xx system.”