In addition, the absence of biomarkers for CAR-T therapy makes it difficult to tailor CAR treatments to patients. Current biomarkers for baseline characteristics, CAR-T cell function, long-term survival, and toxicities are insufficient, making it challenging to guide treatment decisions properly. In the context of implementing new solutions to improve T cell persistence, biomarkers become even more critical to optimize the treatment. More research should be done to validate current biomarkers and identify new ones.