ABSTRACT During the last decade the field of cancer therapy has been reformed by the development of new and effective treatment modalities with a major focus on immune therapeutic strategies. Beside the successful immune check point antibodies different forms of adoptive cellular immunotherapies have been exploited in the past years. Among these adoptive cell therapy (ACT) based on the infusion of ex vivo expanded tumor infiltrating lymphocytes (TILs) has been the most applied and successful. TIL based ACT is a personalized treatment defined as the infusion of T cells harvested from autologous fresh autologous tumor tissues after ex vivo activation and extensive expansion. The final cell infusionproduct consist of a polyclonal T cell population comprising a highly variable amount and diversity of tumor specific T-cells. The expanded TILs are infused i.v. after one week of intensive lymphodepleting chemotherapy and followed by treatment with high i.v. doses of IL-2. TIL based ACT has yet only been tested in smaller phase I/II studies but these studies consistently confirm an impressive clinical response rate of up to 50% in metastatic melanoma - response rates able to compete with the immune check point antibodies. These impressive results justify the need for a pivotal phase III trial documenting the efficacy of this type of T-cell based Advanced Therapy Medicinal Products (ATMP) in order to pave the way for regulatory approval and implementation of TIL therapy as a new treatment standard in oncology practice. The complexity and severe acute toxicity associated with this treatment is likely to significantly limit the dissemination of TIL therapy to cancer centers outside highly specialized units. Much of the toxicity is associated with high-dose IL-2 and recent data have questioned the need for this high dose regimen. Thus, the role of IL-2 dosing requires further clarification. Other approaches might contribute to the improved efficacy of TIL therapy. These strategies could specifically aim at increasing the anti-tumor activity of T cell products, or at improving host conditioning for a better in vivo TIL survival and tumor targeting by immune sensitization of tumors. Furthermore, initiatives to extend TIL therapy to other diagnoses are ongoing. Disclosure: I.M. Svane: limited research grant has been recieved from BMS and Roche.