Disclosed herein is a method for ex vivo expanding tumor-infiltrating lymphocytes for use in adoptive cell therapy (ACT). The method involves culturing tumor fragments from the subject in a culture medium containing IL-2 and a 41BB agonist in an amount effective to expand tumor-infiltrating lymphocytes with enriched tumor-reactivity and specificity. Also disclosed is a method for treating a tumor in a subject that involves treating the subject with nonmyeloablative lymphodepleting chemotherapy, and administering tumor-infiltrating lymphocytes expanded by the disclosed methods.
