An alphavirus vector overcomes the presence of neutralizing antibodies and elevated numbers of Tregs to induce immune responses in humans with advanced cancer
Michael A. Morse, … , Jonathan Smith, H. Kim Lyerly
Michael A. Morse, … , Jonathan Smith, H. Kim Lyerly
Published August 2, 2010
Citation Information: J Clin Invest. 2010;120(9):3234-3241. https://doi.org/10.1172/JCI42672.
View: Text | PDF
Research Article

An alphavirus vector overcomes the presence of neutralizing antibodies and elevated numbers of Tregs to induce immune responses in humans with advanced cancer

Abstract

Therapeutic anticancer vaccines are designed to boost patients’ immune responses to tumors. One approach is to use a viral vector to deliver antigen to in situ DCs, which then activate tumor-specific T cell and antibody responses. However, vector-specific neutralizing antibodies and suppressive cell populations such as Tregs remain great challenges to the efficacy of this approach. We report here that an alphavirus vector, packaged in virus-like replicon particles (VRP) and capable of efficiently infecting DCs, could be repeatedly administered to patients with metastatic cancer expressing the tumor antigen carcinoembryonic antigen (CEA) and that it overcame high titers of neutralizing antibodies and elevated Treg levels to induce clinically relevant CEA-specific T cell and antibody responses. The CEA-specific antibodies mediated antibody-dependent cellular cytotoxicity against tumor cells from human colorectal cancer metastases. In addition, patients with CEA-specific T cell responses exhibited longer overall survival. These data suggest that VRP-based vectors can overcome the presence of neutralizing antibodies to break tolerance to self antigen and may be clinically useful for immunotherapy in the setting of tumor-induced immunosuppression.

Authors

Michael A. Morse, Amy C. Hobeika, Takuya Osada, Peter Berglund, Bolyn Hubby, Sarah Negri, Donna Niedzwiecki, Gayathri R. Devi, Bruce K. Burnett, Timothy M. Clay, Jonathan Smith, H. Kim Lyerly

×

Figure 2

Immune analysis following VRP-CEA(6D) vaccination.

Options: View larger image (or click on image) Download as PowerPoint
Immune analysis following VRP-CEA(6D) vaccination. Patient sera or PBMCs...
Patient sera or PBMCs were analyzed before and after VRP-CEA(6D) for each immunization for MTD cohort by (A) anti-VRP microneutralization assay; (B) CEA ELISA; (C) VRP-CEA ELISpot; and (D) intracellular IFN-γ. (A) Patient sera were analyzed for anti-VRP antibodies by microneutralization assay for weeks 0, 3, 6, 9, and 12. The antibody titer is presented for each week as mean ± SD. The endpoint titer was defined as the last serum dilution at which there was at least 80% reduction in the number of GFP-positive cells compared with control wells. (B) Patient sera were tested against CEA protein by ELISA for weeks 0, 3, 6, 9, and 12. The antibody titer is represented over the course of the 4 vaccinations as mean ± SEM. A single patient with an outlier titer of 1:1,600 at week 9 was not included in the data presented in the graph but was included for statistical analysis. *P = 0.02. (C) Patient PBMCs were stimulated with VRP-CEA (MOI 10) in an ELISpot assay. The number of IFN-γ–producing cells per 106 PBMCs is presented as mean ± SEM. *P = 0.01; **P = 0.005. (D) Patient PBMCs were stimulated with VRP-CEA (MOI 1) and incubated for 12 hours in an intracellular cytokine assay. The percentage of cells that were CD4+CD69+IFN-γ+ is presented as mean ± SEM. Time of vaccinations is represented by arrows on the x axis of graph (D). Regression analysis with repeated measures was used to analyze assay results over time. Time points where the mean significantly differed from baseline are indicated on the graph (P values are adjusted for multiple comparisons). *P = 0.01.