Sara Zalba1,2, María J Garrido3,4, María Merino5, Teresa Lozano6,7, Noelia Casares6,7, Hugo Lana5, Iñaki F Troconiz5,7, Timo L M Ten Hagen8, Grazyna Kochan7,9, Pedro Berraondo6,7. 1. Department of Pharmaceutical Technology and Chemistry, School of Pharmacy, University of Navarra, 31008, Pamplona, Navarra, Spain. szalbaot@unav.es. 2. Navarra Institute for Health Research (IdisNA), Pamplona, Spain. szalbaot@unav.es. 3. Department of Pharmaceutical Technology and Chemistry, School of Pharmacy, University of Navarra, 31008, Pamplona, Navarra, Spain. mgarrido@unav.es. 4. Navarra Institute for Health Research (IdisNA), Pamplona, Spain. mgarrido@unav.es. 5. Department of Pharmaceutical Technology and Chemistry, School of Pharmacy, University of Navarra, 31008, Pamplona, Navarra, Spain. 6. Program of Immunology and Immunotherapy, CIMA-Universidad de Navarra, Pamplona, Spain. 7. Navarra Institute for Health Research (IdisNA), Pamplona, Spain. 8. Laboratory of Experimental Oncology, Erasmus Medical Center, Rotterdam, The Netherlands. 9. Department of Oncology, Navarrabiomed-Biomedical Research Centre, Pamplona, Spain.
Abstract
BACKGROUND: The immunomodulation of the antitumor response driven by immunocheckpoint inhibitors (ICIs) such as PD-L1 (Programmed Death Ligand-1) monoclonal antibody (α-PD-L1) have shown relevant clinical outcomes in a subset of patients. This fact has led to the search for rational combinations with other therapeutic agents such as Doxorubicin (Dox), which cytotoxicity involves an immune activation that may enhance ICI response. Therefore, this study aims to evaluate the combination of chemotherapy and ICI by developing Dox Immunoliposomes functionalized with monovalent-variable fragments (Fab') of α-PD-L1. RESULTS: Immunoliposomes were assayed in vitro and in vivo in a B16 OVA melanoma murine cell line over-expressing PD-L1. Here, immune system activation in tumor, spleen and lymph nodes, together with the antitumor efficacy were evaluated. Results showed that immunoliposomes bound specifically to PD-L1+ cells, yielding higher cell interaction and Dox internalization, and decreasing up to 30-fold the IC50, compared to conventional liposomes. This mechanism supported a higher in vivo response. Indeed, immunoliposomes promoted full tumor regression in 20% of mice and increased in 1 month the survival rate. This formulation was the only treatment able to induce significant (p < 0.01) increase of activated tumor specific cytotoxic T lymphocytes at the tumor site. CONCLUSION: PD-L1 targeted liposomes encapsulating Dox have proved to be a rational combination able to enhance the modulation of the immune system by blocking PD-L1 and selectively internalizing Dox, thus successfully providing a dual activity offered by both, chemo and immune therapeutic strategies.
BACKGROUND: The immunomodulation of the antitumor response driven by immunocheckpoint inhibitors (ICIs) such as PD-L1 (Programmed Death Ligand-1) monoclonal antibody (α-PD-L1) have shown relevant clinical outcomes in a subset of patients. This fact has led to the search for rational combinations with other therapeutic agents such as Doxorubicin (Dox), which cytotoxicity involves an immune activation that may enhance ICI response. Therefore, this study aims to evaluate the combination of chemotherapy and ICI by developing Dox Immunoliposomes functionalized with monovalent-variable fragments (Fab') of α-PD-L1. RESULTS: Immunoliposomes were assayed in vitro and in vivo in a B16 OVA melanomamurine cell line over-expressing PD-L1. Here, immune system activation in tumor, spleen and lymph nodes, together with the antitumor efficacy were evaluated. Results showed that immunoliposomes bound specifically to PD-L1+ cells, yielding higher cell interaction and Dox internalization, and decreasing up to 30-fold the IC50, compared to conventional liposomes. This mechanism supported a higher in vivo response. Indeed, immunoliposomes promoted full tumor regression in 20% of mice and increased in 1 month the survival rate. This formulation was the only treatment able to induce significant (p < 0.01) increase of activated tumor specific cytotoxic T lymphocytes at the tumor site. CONCLUSION:PD-L1 targeted liposomes encapsulating Dox have proved to be a rational combination able to enhance the modulation of the immune system by blocking PD-L1 and selectively internalizing Dox, thus successfully providing a dual activity offered by both, chemo and immune therapeutic strategies.
Authors: Ana M Contreras-Sandoval; María Merino; Marcos Vasquez; Iñaki F Trocóniz; Pedro Berraondo; María J Garrido Journal: Oncotarget Date: 2016-11-22