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Cancer immunotherapies under development have generally focused on either stimulating T cell immunity or driving antibody-directed effector functions of the innate immune system such as antibody-dependent cell-mediated cytotoxicity (ADCC). We find that a combination of an anti-tumor antigen antibody and an untargeted IL-2 fusion protein with delayed systemic clearance induces significant tumor control in aggressive isogenic tumor models via a concerted innate and adaptive response involving neutrophils, NK cells, macrophages, and CD8+ T cells. This combination therapy induces an intratumoral “cytokine storm” and extensive lymphocyte infiltration. Adoptive transfer of anti-tumor T cells together with this combination therapy leads to robust cures of established tumors and development of immunological memory., National Cancer Institute (U.S.) (Grant NCI CA174795), National Institute of General Medical Sciences (U.S.). Biotechnology Training Program, National Science Foundation (U.S.). Graduate Research Fellowship Program

In adoptive cell therapy (ACT), autologous tumor-specific T-cells isolated from cancer patients are activated and expanded ex vivo, then infused back into the individual to eliminate metastatic tumors. A major limitation of this promising approach is the rapid loss of ACT T-cell effector function in vivo due to the highly immunosuppressive environment in tumors. Protection of T-cells from immunosuppressive signals can be achieved by systemic administration of supporting adjuvant drugs such as interleukins, chemotherapy, and other immunomodulators, but these adjuvant treatments are often accompanied by serious toxicities and may still fail to optimally stimulate lymphocytes in all tumor and lymphoid compartments. Here we propose a novel strategy to repeatedly stimulate or track ACT T-cells, using cytokines or ACT-cell-specific antibodies as ligands to target PEGylated liposomes to transferred T-cells in vivo. Using F(ab′)[subscript 2] fragments against a unique cell surface antigen on ACT cells (Thy1.1) or an engineered interleukin-2 (IL-2) molecule on an Fc framework as targeting ligands, we demonstrate that > 95% of ACT cells can be conjugated with liposomes following a single injection in vivo. Further, we show that IL-2-conjugated liposomes both target ACT cells and are capable of inducing repeated waves of ACT T-cell proliferation in tumor-bearing mice. These results demonstrate the feasibility of repeated functional targeting of T-cells in vivo, which will enable delivery of imaging contrast agents, immunomodulators, or chemotherapy agents in adoptive cell therapy regimens., National Institutes of Health (U.S.) (CA140476), National Institutes of Health (U.S.) (CA172164), United States. Dept. of Defense (Contract W81XWH-10-1-0290), National Cancer Institute (U.S.) (Koch Institute Support (core) Grant P30-CA14051)

In adoptive cell therapy (ACT), autologous tumor-specific T-cells isolated from cancer patients are activated and expanded ex vivo, then infused back into the individual to eliminate metastatic tumors. A major limitation of this promising approach is the rapid loss of ACT T-cell effector function in vivo due to the highly immunosuppressive environment in tumors. Protection of T-cells from immunosuppressive signals can be achieved by systemic administration of supporting adjuvant drugs such as interleukins, chemotherapy, and other immunomodulators, but these adjuvant treatments are often accompanied by serious toxicities and may still fail to optimally stimulate lymphocytes in all tumor and lymphoid compartments. Here we propose a novel strategy to repeatedly stimulate or track ACT T-cells, using cytokines or ACT-cell-specific antibodies as ligands to target PEGylated liposomes to transferred T-cells in vivo. Using F(ab′)[subscript 2] fragments against a unique cell surface antigen on ACT cells (Thy1.1) or an engineered interleukin-2 (IL-2) molecule on an Fc framework as targeting ligands, we demonstrate that > 95% of ACT cells can be conjugated with liposomes following a single injection in vivo. Further, we show that IL-2-conjugated liposomes both target ACT cells and are capable of inducing repeated waves of ACT T-cell proliferation in tumor-bearing mice. These results demonstrate the feasibility of repeated functional targeting of T-cells in vivo, which will enable delivery of imaging contrast agents, immunomodulators, or chemotherapy agents in adoptive cell therapy regimens., National Institutes of Health (U.S.) (CA140476), National Institutes of Health (U.S.) (CA172164), United States. Dept. of Defense (Contract W81XWH-10-1-0290), National Cancer Institute (U.S.) (Koch Institute Support (core) Grant P30-CA14051)