Targeting HIV Reservoir in Infected CD4 T Cells by Dual-Affinity Re-targeting Molecules (DARTs) that Bind HIV Envelope and Recruit Cytotoxic T Cells

Abstract

HIV reservoirs and production of viral antigens are not eliminated in chronically infected participants treated with combination antiretroviral therapy (cART). Novel therapeutic strategies aiming at viral reservoir elimination are needed to address chronic immune dysfunction and non-AIDS morbidities that exist despite effective cART. The HIV envelope protein (Env) is emerging as a highly specific viral target for therapeutic elimination of the persistent HIV-infected reservoirs via antibody-mediated cell killing. Dual-Affinity Re-Targeting (DART) molecules exhibit a distinct mechanism of action via binding the cell surface target antigen and simultaneously engaging CD3 on cytotoxic T lymphocytes (CTLs). We designed and evaluated Env-specific DARTs (HIVxCD3 DARTs) derived from known antibodies recognizing diverse Env epitopes with or without broadly neutralizing activity. HIVxCD3 DARTs derived from PGT121, PGT145, A32, and 7B2, but not VRC01 or 10E8 antibodies, mediated potent CTL-dependent killing of quiescent primary CD4 T cells infected with diverse HIV isolates. Similar killing activity was also observed with DARTs structurally modified for in vivo half-life extension. In an ex vivo model using cells isolated from HIV-infected participants on cART, combinations of the most potent HIVxCD3 DARTs reduced HIV expression both in quiescent and activated peripheral blood mononuclear cell cultures isolated from HIV-infected participants on suppressive cART. Importantly, HIVxCD3 DARTs did not induce cell-to-cell virus spread in resting or activated CD4 T cell cultures. Collectively, these results provide support for further development of HIVxCD3 DARTs as a promising therapeutic strategy for targeting HIV reservoirs.

HDAC inhibition induces HIV-1 protein and enables immune-based clearance following latency reversal

“…CD4 + T cell viability remained similar across treatment conditions (Supplemental Figure 4). These proof-of-concept studies illustrate HDACis, as well as other latency-reversing agents, can elicit viral protein production to facilitate redirected cell killing and support immune clearance approaches under evaluation (5,17,18,(35)(36)(37)(38)(39).…”

IFITM1 targets HIV-1 latently infected cells for antibody-dependent cytolysis

“…Recently, two papers described the use of dual-affinity re-targeting (DART) proteins aimed at improving T cell-mediated clearance of HIV-1-infected cells (24,25). DARTs were specifically designed to recognize Env-expressing cells and to engage to CD3.…”

MGD011, A CD19 x CD3 Dual-Affinity Retargeting Bi-specific Molecule Incorporating Extended Circulating Half-life for the Treatment of B-Cell Malignancies

“…DART protein engineering, production, and purification MGD011, an Fc-bearing CD19 x CD3 DART protein, was constructed as described (11) using VL and VH sequences from humanized anti-CD19 mAb BU12 (12) and humanized anti-CD3 mAb XR32 (13). The IgG1-derived Fc segment was modified to encode the L234A/L235A mutation to greatly reduce or eliminate FcgR and C1q binding (14).…”