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

Sloan DD, Lam CY, Irrinki A, Liu L, Tsai A, Pace CS, Kaur J, Murry JP, Balakrishnan M, Moore PA, Johnson S, Nordstrom JL, Cihlar T, Koenig S - PLoS Pathog. (2015)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Gilead Sciences, Foster City, California, United States of America.

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.

No MeSH data available.


Related in: MedlinePlus

HIVxCD3 DARTs in basic and MP3 format.(A) Schematics of DARTs in basic and MP3 (Fc-bearing) format are shown. The anti-HIV and anti-CD3 domains are colored in blue and orange, respectively, and the human IgG1 Fc domains are shaded in grey. The chains of the Fc domain are modified to contain L234A/L235A mutations that inhibit Fc binding to activating FcγRs. The chains of the Fc domain do not inhibit binding to FcRn, which prolongs serum half-life and exposure. (B) Pharmacokinetic profile in human FcRn transgenic mice. The A32xCD3 MP3 DART was administered at 5 mg/kg by iv injection and serum concentrations were measured over time (closed circles). For comparison, the serum concentration-time curve for a basic DART with different specificities is shown (open squares). The PK parameters for the A32xCD3 MP3 DART are presented in the table.
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ppat.1005233.g007: HIVxCD3 DARTs in basic and MP3 format.(A) Schematics of DARTs in basic and MP3 (Fc-bearing) format are shown. The anti-HIV and anti-CD3 domains are colored in blue and orange, respectively, and the human IgG1 Fc domains are shaded in grey. The chains of the Fc domain are modified to contain L234A/L235A mutations that inhibit Fc binding to activating FcγRs. The chains of the Fc domain do not inhibit binding to FcRn, which prolongs serum half-life and exposure. (B) Pharmacokinetic profile in human FcRn transgenic mice. The A32xCD3 MP3 DART was administered at 5 mg/kg by iv injection and serum concentrations were measured over time (closed circles). For comparison, the serum concentration-time curve for a basic DART with different specificities is shown (open squares). The PK parameters for the A32xCD3 MP3 DART are presented in the table.

Mentions: The MP3 DART format was developed to prolong the short circulating half-life of basic format DARTs [28]. MP3 DARTs contain a human IgG1 Fc domain that has been mutated (L234A/L235A) to inactivate effector function via binding to FcγRs and/or complement, while retaining binding to the neonatal FcR (FcRn) to engage the IgG salvage pathway (Fig 7A) [56,57]. The MP3 DART format would likely be preferable for clinical applications, as it would reduce dosing frequency while maintaining optimal exposure levels.


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

Sloan DD, Lam CY, Irrinki A, Liu L, Tsai A, Pace CS, Kaur J, Murry JP, Balakrishnan M, Moore PA, Johnson S, Nordstrom JL, Cihlar T, Koenig S - PLoS Pathog. (2015)

HIVxCD3 DARTs in basic and MP3 format.(A) Schematics of DARTs in basic and MP3 (Fc-bearing) format are shown. The anti-HIV and anti-CD3 domains are colored in blue and orange, respectively, and the human IgG1 Fc domains are shaded in grey. The chains of the Fc domain are modified to contain L234A/L235A mutations that inhibit Fc binding to activating FcγRs. The chains of the Fc domain do not inhibit binding to FcRn, which prolongs serum half-life and exposure. (B) Pharmacokinetic profile in human FcRn transgenic mice. The A32xCD3 MP3 DART was administered at 5 mg/kg by iv injection and serum concentrations were measured over time (closed circles). For comparison, the serum concentration-time curve for a basic DART with different specificities is shown (open squares). The PK parameters for the A32xCD3 MP3 DART are presented in the table.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4634948&req=5

ppat.1005233.g007: HIVxCD3 DARTs in basic and MP3 format.(A) Schematics of DARTs in basic and MP3 (Fc-bearing) format are shown. The anti-HIV and anti-CD3 domains are colored in blue and orange, respectively, and the human IgG1 Fc domains are shaded in grey. The chains of the Fc domain are modified to contain L234A/L235A mutations that inhibit Fc binding to activating FcγRs. The chains of the Fc domain do not inhibit binding to FcRn, which prolongs serum half-life and exposure. (B) Pharmacokinetic profile in human FcRn transgenic mice. The A32xCD3 MP3 DART was administered at 5 mg/kg by iv injection and serum concentrations were measured over time (closed circles). For comparison, the serum concentration-time curve for a basic DART with different specificities is shown (open squares). The PK parameters for the A32xCD3 MP3 DART are presented in the table.
Mentions: The MP3 DART format was developed to prolong the short circulating half-life of basic format DARTs [28]. MP3 DARTs contain a human IgG1 Fc domain that has been mutated (L234A/L235A) to inactivate effector function via binding to FcγRs and/or complement, while retaining binding to the neonatal FcR (FcRn) to engage the IgG salvage pathway (Fig 7A) [56,57]. The MP3 DART format would likely be preferable for clinical applications, as it would reduce dosing frequency while maintaining optimal exposure levels.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Gilead Sciences, Foster City, California, United States of America.

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.

No MeSH data available.


Related in: MedlinePlus