RESUMO
The purpose of this study was to assess whether cationic nanoliposomes could address tumor vaccines to dendritic cells in the lungs in vivo. Nanoliposomes were prepared using a cationic lipid, dimethylaminoethanecarbamoyl-cholesterol (DC-cholesterol) or dioleoyltrimethylammoniumpropane (DOTAP), and dipalmitoylphosphatidylcholine (DPPC), the most abundant phospholipid in lung surfactant. The liposomes presented a size below 175 nm and they effectively entrapped tumor antigens, an oligodeoxynucletotide containing CpG motifs (CpG) and the fluorescent dye calcein used as a tracer. Although the liposomes could permanently entrap a large fraction of the actives, they could not sustain their release in vitro. Liposomes made of DOTAP were safe to respiratory cells in vitro, while liposomes composed of DC-cholesterol were cytotoxic. DOTAP nanoliposomes were mainly taken up by alveolar macrophages following delivery to the lungs in mice. Few dendritic cells took up the liposomes, and interstitial macrophages did not take up liposomal calcein more than they took up soluble calcein. Stimulation of the innate immune system using liposomal CpG strongly enhanced uptake of calcein liposomes by all phagocytes in the lungs. Although a small percentage of dendritic cells took up the nanoliposomes, alveolar macrophages represented a major barrier to dendritic cell access in the lungs.
Assuntos
Ilhas de CpG/imunologia , Células Dendríticas/efeitos dos fármacos , Sistemas de Liberação de Medicamentos/métodos , Lipossomos/farmacocinética , Pulmão/citologia , Pulmão/efeitos dos fármacos , Macrófagos Alveolares/efeitos dos fármacos , 1,2-Dipalmitoilfosfatidilcolina/farmacocinética , Adjuvantes Imunológicos/uso terapêutico , Animais , Vacinas Anticâncer/uso terapêutico , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Colesterol/análogos & derivados , Colesterol/farmacocinética , Ácidos Graxos Monoinsaturados/farmacocinética , Feminino , Fluoresceínas/farmacocinética , Corantes Fluorescentes/farmacocinética , Lipopeptídeos , Lipossomos/síntese química , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/terapia , Antígeno MART-1/farmacologia , Camundongos , Nanopartículas/química , Compostos de Amônio Quaternário/farmacocinética , Distribuição Tecidual , Antígeno gp100 de Melanoma/farmacologiaRESUMO
Anticancer vaccination is a promising approach to increase the efficacy of cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and programmed death ligand 1 (PD-L1) checkpoint blockade therapies. However, the landmark FDA registration trial for anti-CTLA-4 therapy (ipilimumab) revealed a complete lack of benefit of adding vaccination with gp100 peptide formulated in incomplete Freund's adjuvant (IFA). Here, using a mouse model of melanoma, we found that gp100 vaccination induced gp100-specific effector T cells (Teffs), which dominantly forced trafficking of anti-CTLA-4-induced, non-gp100-specific Teffs away from the tumor, reducing tumor control. The inflamed vaccination site subsequently also sequestered and destroyed anti-CTLA-4-induced Teffs with specificities for tumor antigens other than gp100, reducing the antitumor efficacy of anti-CTLA-4 therapy. Mechanistically, Teffs at the vaccination site recruited inflammatory monocytes, which in turn attracted additional Teffs in a vicious cycle mediated by IFN-γ, CXCR3, ICAM-1, and CCL2, dependent on IFA formulation. In contrast, nonpersistent vaccine formulations based on dendritic cells, viral vectors, or water-soluble peptides potently synergized with checkpoint blockade of both CTLA-4 and PD-L1 and induced complete tumor regression, including in settings of primary resistance to dual checkpoint blockade. We conclude that cancer vaccine formulation can dominantly determine synergy, or lack thereof, with CTLA-4 and PD-L1 checkpoint blockade therapy for cancer.