Institute of Biomedical Sciences

Title

Antibody-Secreting T Cells Engineered for Tripartite Immune Response Against HIV

Document Type

Poster

Abstract Category

HIV/AIDS

Keywords

HIV, Immunotherapy

Publication Date

Spring 5-1-2019

Abstract

Antiretroviral therapies have improved outcomes in HIV/AIDS patients but are unable to cure infection. Several strategies appear promising though they have only shown transient decrease in viral load: (1) strong virus-specific CD8+ T cell responses seen in elite controllers, (2) neutralizing antibodies from patient sera prevent virus from infecting cells, and (3) a subset of participants of the RV144 vaccine trial able to elicit high levels of ADCC. The simultaneous use of all three as the basis of a single therapeutic has never been explored. We sought to genetically modify HIV-specific T cells from HIV-naïve donors (dHXTC) to secrete a neutralizing antibody directed against HIV envelope (10-1074). We designed two transgene constructs. The first, a 10-1074 antibody comprised of 10-1074 heavy and light chains fused to IgG3 Fc to elicit ADCC, with truncated CD19 as selectable marker. The second, a 10-1074 bispecific killer cell engager molecule composed of the 10-1074 single chain variable fragment (scFv) and CD16 scFv. We then modified HIV-specific T cells to express these constructs by expanding cells from HIV-naïve donors using antigens expressing overlapping HIV antigens in the presence of cytokines. T cells retained antigen specificity against HIV gag, nef, and pol (untrans: 113.74+/-91.56 INFSFC/1x105 cells against HIV peptide vs 8.25+/-12.60 INFSFC/1x105 cells against irrelevant peptide, n=6; 10-1074 Ab: 121.47+/-75.23 against HIV peptide vs 5.92+/-7.00 against irrelevant peptide, n=6; 10-1074 BiKE: 140.70+/-31.66 against HIV peptide vs 26.30+/-33.78 against irrelevant peptide, n=5) following transduction (10-1074 Ab: 30.58+/-22.90%, n=7; 10-1074 BiKE: 44.63+/-19.04%, n=6) with the 10-1074 constructs. These cells secreted 10-1074 antibodies (10-1074 Ab: 138.28+/-82.57 ng/mL, n=5, p=0.0203 compared to untransduced cells). Functional analysis of the secreted engineered 10-1074 bnAb in culture supernatants showed higher neutralization of HIV compared to their untransduced counterparts (10-1074 Ab: 44.05+/-14.19% compared to 6.49+/-1.00% in untransduced, n=3), the ability to elicit ADCC as shown by increased NK cytotoxicity (10-1074 Ab: +10.5%, n=2; 10-1074 BiKE: +19.40%, n=3), and a greater anti-viral response in a p24 viral inhibition assay. These preliminary results show that HIV-specific T cells can be engineered to mount a tripartite attack against HIV. We demonstrate: (1) direct T cell cytotoxicity targeting processed HIV antigens, (2) bnAb ability to elicit ADCC against surface expressed HIV envelope and (3) neutralize free HIV. This tripartite approach allows for synergy between immune arms, broadens the target range of the immune therapy, and provides further insight into what defines an effective anti-HIV response.

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Presented at Research Days 2019.

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Antibody-Secreting T Cells Engineered for Tripartite Immune Response Against HIV

Antiretroviral therapies have improved outcomes in HIV/AIDS patients but are unable to cure infection. Several strategies appear promising though they have only shown transient decrease in viral load: (1) strong virus-specific CD8+ T cell responses seen in elite controllers, (2) neutralizing antibodies from patient sera prevent virus from infecting cells, and (3) a subset of participants of the RV144 vaccine trial able to elicit high levels of ADCC. The simultaneous use of all three as the basis of a single therapeutic has never been explored. We sought to genetically modify HIV-specific T cells from HIV-naïve donors (dHXTC) to secrete a neutralizing antibody directed against HIV envelope (10-1074). We designed two transgene constructs. The first, a 10-1074 antibody comprised of 10-1074 heavy and light chains fused to IgG3 Fc to elicit ADCC, with truncated CD19 as selectable marker. The second, a 10-1074 bispecific killer cell engager molecule composed of the 10-1074 single chain variable fragment (scFv) and CD16 scFv. We then modified HIV-specific T cells to express these constructs by expanding cells from HIV-naïve donors using antigens expressing overlapping HIV antigens in the presence of cytokines. T cells retained antigen specificity against HIV gag, nef, and pol (untrans: 113.74+/-91.56 INFSFC/1x105 cells against HIV peptide vs 8.25+/-12.60 INFSFC/1x105 cells against irrelevant peptide, n=6; 10-1074 Ab: 121.47+/-75.23 against HIV peptide vs 5.92+/-7.00 against irrelevant peptide, n=6; 10-1074 BiKE: 140.70+/-31.66 against HIV peptide vs 26.30+/-33.78 against irrelevant peptide, n=5) following transduction (10-1074 Ab: 30.58+/-22.90%, n=7; 10-1074 BiKE: 44.63+/-19.04%, n=6) with the 10-1074 constructs. These cells secreted 10-1074 antibodies (10-1074 Ab: 138.28+/-82.57 ng/mL, n=5, p=0.0203 compared to untransduced cells). Functional analysis of the secreted engineered 10-1074 bnAb in culture supernatants showed higher neutralization of HIV compared to their untransduced counterparts (10-1074 Ab: 44.05+/-14.19% compared to 6.49+/-1.00% in untransduced, n=3), the ability to elicit ADCC as shown by increased NK cytotoxicity (10-1074 Ab: +10.5%, n=2; 10-1074 BiKE: +19.40%, n=3), and a greater anti-viral response in a p24 viral inhibition assay. These preliminary results show that HIV-specific T cells can be engineered to mount a tripartite attack against HIV. We demonstrate: (1) direct T cell cytotoxicity targeting processed HIV antigens, (2) bnAb ability to elicit ADCC against surface expressed HIV envelope and (3) neutralize free HIV. This tripartite approach allows for synergy between immune arms, broadens the target range of the immune therapy, and provides further insight into what defines an effective anti-HIV response.