Melanoma immunotherapy using mature DCs expressing the constitutive proteasome
Jens Dannull, … , Douglas S. Tyler, Scott K. Pruitt
Jens Dannull, … , Douglas S. Tyler, Scott K. Pruitt
Published June 24, 2013
Citation Information: J Clin Invest. 2013;123(7):3135-3145. https://doi.org/10.1172/JCI67544.
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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

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Figure 3

Clinical timeline for vaccine generation and administration and immunologic testing.

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Clinical timeline for vaccine generation and administration and immunolo...
Subjects were screened to determine eligibility (week –6), and then underwent surgery or a biopsy of their metastatic melanoma (week –5). Leukapheresis was then performed (week –4) for collection of PBMCs. The monocytes were then isolated from the PBMCs, electroporated with the appropriate siRNAs, and differentiated into immature DCs over a period of 5 days. After induction of maturation for 2 days, DCs were electroporated with TAA RNAs, then cryopreserved. Over the next 3 weeks, the vaccine was test thawed, and both sterility testing and DC phenotypic analysis was performed. Subjects were then vaccinated weekly (weeks 0–5) by intradermal injection, as indicated. Blood was collected at the time of each vaccination, and repeat leukapheresis was performed 2 weeks after the final vaccination (week 7) for isolation of T cells and monocytes, which were used to assess antitumor immune responses.