Advances and prospects in tumor infiltrating lymphocyte therapy

Tumor-infiltrating lymphocyte (TIL) therapy in adoptive T-cell therapy (ACT) has already caused durable regression in a variety of cancer types due to T-cell persistence, clinical activity, and duration of objective response and safety. TILs are composed of polyclonal effector T-cells specific to heterogenetic tumor antigens, reasonably providing a promising means for tumor therapy. In addition, their expansion in vitro can release them from the suppressive tumor microenvironment. Even though significant advances have been made in the procedure of TIL therapy, from TIL isolation, modification, expansion, and infusion back to the patient to target the tumor, strategy optimization is always ongoing to overcome drawbacks such as a complex process, options for the lineage differentiation status of TILs, and sufficient trafficking of TILs to the tumor. In this review, we summarize the current advances of TIL therapy, raise problem-based optimization strategies, and provide future perspectives on next-generation TIL therapy as a potential avenue for enhancing cell-based immunotherapy.