Melanoma immunotherapy using mature DCs expressing the constitutive proteasome.
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.


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


BACKGROUND
Clinicaltrials.gov NCT00672542.


BACKGROUND
Duke Clinical Research Institute/Duke Translational Medicine Institute, Duke Melanoma Consortium, and Duke University Department of Surgery.
Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA.
Jens
J
Dannull
N Rebecca
NR
Haley
Gary
G
Archer
Smita
S
Nair
David
D
Boczkowski
Mark
M
Harper
Nicole
N
De Rosa
Nancy
N
Pickett
Paul J
PJ
Mosca
James
J
Burchette
Maria A
MA
Selim
Duane A
DA
Mitchell
John
J
Sampson
Douglas S
DS
Tyler
Scott K
SK
Pruitt
D000368:Aged; D000369:Aged, 80 and over; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D019496:Cancer Vaccines; D003713:Dendritic Cells / Q000201:enzymology / Q000637:transplantation*; D005260:Female; D055785:Gene Knockdown Techniques; D006801:Humans; D007167:Immunotherapy; D008207:Lymphatic Metastasis; D008297:Male; D008545:Melanoma / Q000276:immunology / Q000556:secondary / Q000628:therapy*; D008875:Middle Aged; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D016896:Treatment Outcome; D014407:Tumor Cells, Cultured
D019496:Cancer Vaccines; D021122:Protein Subunits; D034741:RNA, Small Interfering; D046988:Proteasome Endopeptidase Complex