Melanoma immunotherapy using mature DCs expressing the constitutive proteasome
Jens Dannull, N. Rebecca Haley, Gary Archer, Smita Nair, David Boczkowski, Mark Harper, Nicole De Rosa, Nancy Pickett, Paul J. Mosca, James Burchette, Maria A. Selim, Duane A. Mitchell, John Sampson, Douglas S. Tyler, Scott K. Pruitt
Jens Dannull, N. Rebecca Haley, Gary Archer, Smita Nair, David Boczkowski, Mark Harper, Nicole De Rosa, Nancy Pickett, Paul J. Mosca, James Burchette, Maria A. Selim, Duane A. Mitchell, John Sampson, Douglas S. Tyler, Scott K. Pruitt
View: Text | PDF
Clinical Research and Public Health Oncology

Melanoma immunotherapy using mature DCs expressing the constitutive proteasome

Abstract

Background. 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.

Methods. 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).

Results. 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.

Conclusion. These results suggest that the efficacy of melanoma DC–based immunotherapy is enhanced when tumor antigen–loaded DCs used for vaccination express cPs.

Trial registration. Clinicaltrials.gov NCT00672542.

Funding. Duke Clinical Research Institute/Duke Translational Medicine Institute, Duke Melanoma Consortium, and Duke University Department of Surgery.

Authors

Jens Dannull, N. Rebecca Haley, Gary Archer, Smita Nair, David Boczkowski, Mark Harper, Nicole De Rosa, Nancy Pickett, Paul J. Mosca, James Burchette, Maria A. Selim, Duane A. Mitchell, John Sampson, Douglas S. Tyler, Scott K. Pruitt

×

Figure 8

Peripheral blood levels of CD8+ T cells binding HLA-A2 tetramers loaded with melanoma TAA–derived peptides generated by the cP.

Options: View larger image (or click on image) Download as PowerPoint
Peripheral blood levels of CD8+ T cells binding HLA-A2 tetramers loaded ...
For 6 of the 7 subjects in this trial that were HLA-A2+, sufficient numbers of collected peripheral blood T cells were available for tetramer binding analysis. Using blood samples collected before and approximately 1 month after completion of the course of vaccination, PBMCs were isolated and then stained with an anti-CD8 FITC-conjugated mAb and PE-conjugated HLA-A2 tetramers loaded with cP-generated peptides derived from MART1 or gp100. The pre- and postvaccination percentages of CD8+tetramer+ T cells are graphed for subjects 10, 11, and 12 (each vaccinated with TAA RNA–transfected DCs derived from iP siRNA–transfected monocytes), and for subjects 2, 4, and 7, whose TAA RNA–transfected DC vaccine was derived from monocytes that were either untransfected (subjects 2 and 4) or transfected with control siRNA (subject 7). Representative FACS profiles are shown for pre- and postassessment of MART1 CD8+tetramer+ cells for subjects 2 and 12.