Melanoma immunotherapy using mature DCs expressing the constitutive proteasome

• Published in: The Journal of clinical investigation 2013-07, Vol.123 (7), p.3135-3145
• Main Authors: Dannull, Jens, Haley, N Rebecca, Archer, Gary, Nair, Smita, Boczkowski, David, Harper, Mark, De Rosa, Nicole, Pickett, Nancy, Mosca, Paul J, Burchette, James, Selim, Maria A, Mitchell, Duane A, Sampson, John, Tyler, Douglas S, Pruitt, Scott K
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; Biomedical research; Cancer; Cancer Vaccines; Care and treatment; CD8-Positive T-Lymphocytes - immunology; CD8-Positive T-Lymphocytes - metabolism; Clinical Medicine; Clinical trials; Dendritic cells; Dendritic Cells - enzymology; Dendritic Cells - transplantation; DNA methylation; Drug therapy; Female; Gene Knockdown Techniques; Genetic aspects; Humans; Immunology; Immunotherapy; Lymphatic Metastasis; Male; Melanoma; Melanoma - immunology; Melanoma - secondary; Melanoma - therapy; Middle Aged; Peptides; Proteasome Endopeptidase Complex - genetics; Proteasome Endopeptidase Complex - metabolism; Protein Subunits - genetics; Protein Subunits - metabolism; RNA, Small Interfering - genetics; Treatment Outcome; Tumor Cells, Cultured
• ISSN: 0021-9738; 1558-8238
• DOI: 10.1172/JCI67544

Many cancers, including melanoma, exclusively express constitutive proteasomes (cPs) and are unable to express immunoproteasomes (iPs). In contrast, mature DCs used for immunotherapy exclusively express iPs. Since proteasomes generate peptides presented by HLA class I molecules, we hypothesized that mature melanoma antigen-loaded DCs engineered to process antigens through cPs would be superior inducers of antimelanoma immunity in vivo. Subjects with metastatic melanoma were vaccinated with mature DCs transfected with RNAs encoding melanoma antigens MART1, MAGE-3, gp100, and tyrosinase. These DCs were derived from monocytes that were untransfected (Arm A; n = 4), transfected with control siRNA (Arm B; n = 3), or transfected with siRNAs targeting the 3 inducible iP subunits (Arm C; n = 5). Vaccination stimulated antigen-specific T cell responses in all subjects, which peaked after 3-4 vaccinations, but remained elevated in Arm C subjects. Also in Arm C, circulating melanoma cell levels (as detected by quantitative PCR) fell, and T cell lytic activity against autologous melanoma was induced. In HLA-A2⁺ subjects, CD8⁺ T cells that bound tetramers loaded with cP-derived melanoma antigenic peptides were found in the peripheral blood only in Arm C subjects. Of 2 subjects with active disease (both in Arm C), one had a partial clinical response, while the other, who exhibited diffuse dermal and soft tissue metastases, had a complete response. These results suggest that the efficacy of melanoma DC-based immunotherapy is enhanced when tumor antigen-loaded DCs used for vaccination express cPs. Clinicaltrials.gov NCT00672542. Duke Clinical Research Institute/Duke Translational Medicine Institute, Duke Melanoma Consortium, and Duke University Department of Surgery.