RESUMO
Antigen-specific immunotherapy of cancer depends on a consistent source of well-defined protein antigen. Production of recombinant protein offers the obvious solution to this problem but few comparisons of recombinant and native proteins in cellular immune assays have been reported. We report expression of a putative immunotherapy antigen, prostate-specific membrane antigen (PSMA), in insect cells using a baculovirus vector. T cells stimulated with recombinant PSMA or native PSMA derived from the LNCaP cell line recognized both native PSMA and recombinant, baculoviral PSMA. These data indicate that PSMA produced in Sf9 cells is immunologically cross-reactive with native PSMA and therefore suitable for immunotherapy as it is recognized by both cellular and humoral immune responses.
Assuntos
Baculoviridae/química , Antígeno Prostático Específico/imunologia , Antígeno Prostático Específico/isolamento & purificação , Neoplasias da Próstata/imunologia , Linfócitos T/imunologia , Formação de Anticorpos , Baculoviridae/genética , Baculoviridae/imunologia , Western Blotting , Complexo CD3/análise , Complexo CD3/imunologia , Antígenos CD4/análise , Antígenos CD4/imunologia , Antígenos CD8/análise , Antígenos CD8/imunologia , Membrana Celular/imunologia , Vetores Genéticos , Humanos , Imunidade Celular , Imunoterapia/métodos , Masculino , Neoplasias da Próstata/terapia , Biossíntese de Proteínas , Recombinação Genética , Sensibilidade e Especificidade , Células Tumorais CultivadasRESUMO
BACKGROUND: In this paper we describe our program for the immune monitoring of phase II participants given dendritic cell (DC)/prostate-specific membrane antigen (PSMA)-based immunotherapy, and we also present some initial findings. METHODS: Phase II subjects received six administrations of autologous dendritic cells exogenously pulsed with two peptides derived from PSMA. Prior to the initial infusion, and following each treatment, peripheral blood mononuclear cells (PBMC) were collected for the generation of dendritic cells as well as for comprehensive immune monitoring. RESULTS: Thus far, an increase in PSMA-peptide-specific as well as overall cellular reactivity has been observed in several patients receiving DC plus PSM-P1 and -P2, as measured by delayed-type hypersensitivity (DTH) test and enzyme-linked immunosorbant assay (ELISA). CONCLUSIONS: Our initial observations using an ELISA and DTH test indicate that we are enhancing cellular immunity in prostate cancer patients following infusion with DC plus PSMA-derived peptides. Several methods are underway to comprehensively monitor both cell-mediated and humoral immune responsiveness, including: determining anti-PSMA serum antibody titers, testing immunogen-restricted responder-cell proliferation and cytotoxicity, assessing aberrations in signal transduction, antigen processing, and presentation, and measuring soluble factors that may promote tumor outgrowth.
Assuntos
Antígenos de Neoplasias/imunologia , Antígenos de Superfície , Carboxipeptidases/imunologia , Células Dendríticas/imunologia , Antígenos HLA-A/imunologia , Imunoterapia Adotiva/métodos , Neoplasias da Próstata/imunologia , Neoplasias da Próstata/terapia , Linfócitos T/imunologia , Ensaio de Imunoadsorção Enzimática , Genes MHC Classe I , Glutamato Carboxipeptidase II , Humanos , Masculino , Resultado do TratamentoRESUMO
Our approach to prostate cancer immunotherapy involves two components dendritic cells as antigen-presenting cells; and the antigen used to target T-cell attack, HLA-A0201-associated peptides from prostate specific membrane antigen (PSMA). We have conducted a phase I dose-ranging study in 51 men with advanced prostate cancer, using dendritic cells pulsed with a PSMA peptide. no significant toxicity was observed. In that study, T-cell response was enhanced, with seven men meeting NCPC and PSA criteria for partial response. We are now conducting a phase II study with 67 men, who will receive 6 infusions of dendritic cells that have been pulsed with 2 PSMA peptides, at 6-week intervals. The phase II study design and rationale is described in this paper.