Trafficking of T cells into tumors

T cells are a crucial component of the immune response to infection and cancer. In addition to coordinating immunity in lymphoid tissue, T cells play a vital role at the disease site, which relies on their efficient and specific trafficking capabilities. The process of T-cell trafficking is highly dynamic, involving a series of distinct processes, which include rolling, adhesion, extravasation, and chemotaxis. Trafficking of T cells to the tumor microenvironment is critical for the success of cancer immunotherapies such as adoptive cellular transfer. Although this approach has achieved some remarkable responses in patients with advanced melanoma and hematologic malignancy, the success against solid cancers has been more moderate. One of the major challenges for adoptive immunotherapy is to be able to effectively target a higher frequency of T cells to the tumor microenvironment, overcoming hurdles associated with immunosuppression and aberrant vasculature. This review summarizes recent advances in our understanding of T-cell migration in solid cancer and immunotherapy based on the adoptive transfer of natural or genetically engineered tumor-specific T cells and discusses new strategies that may enhance the trafficking of these cells, leading to effective eradication of solid cancer and metastases.