Blocking α ₄ β ₇ integrin delays viral rebound in SHIV SF162P3 -infected macaques treated with anti-HIV broadly neutralizing antibodies

Broadly neutralizing antibodies and an anti-α4β7 monoclonal antibody prolong viral load control in SHIVSF162P3-infected macaques. Integrin blockade may contribute to HIV control Blocking integrin α4β7 has been shown to have immunomodulatory effects. In a new study, Frank et al. investigated how blocking integrin α4β7 in macaques infected with a simian-human immunodeficiency virus and treated with anti-HIV broadly neutralizing antibodies (bNAbs) could modulate viral load. Their results suggested that the combination of α4β7 blockade and bNAbs may have controlled the virus better and longer than treatment with bNAbs alone. These findings need to be recapitulated in larger studies with a focus on determining the mechanisms and the duration of virologic control, before they can be translated into clinical settings. Anti-HIV broadly neutralizing antibodies (bNAbs) may favor development of antiviral immunity by engaging the immune system during immunotherapy. Targeting integrin α4β7 with an anti-α4β7 monoclonal antibody (Rh-α4β7) affects immune responses in SIV/SHIV-infected macaques. To explore the therapeutic potential of combining bNAbs with α4β7 integrin blockade, SHIVSF162P3-infected, viremic rhesus macaques were treated with bNAbs only (VRC07-523LS and PGT128 anti-HIV antibodies) or a combination of bNAbs and Rh-α4β7 or were left untreated as a control. Treatment with bNAbs alone decreased viremia below 200 copies/ml in all macaques, but seven of eight macaques (87.5%) in the bNAbs-only group rebounded within a median of 3 weeks (95% CI: 2 to 9). In contrast, three of six macaques treated with a combination of Rh-α4β7 and bNAbs (50%) maintained a viremia below 200 copies/ml until the end of the follow-up period; viremia in the other three macaques rebounded within a median of 6 weeks (95% CI: 5 to 11). Thus, there was a modest delay in viral rebound in the macaques treated with the combination antibody therapy compared to bNAbs alone. Our study suggests that α4β7 integrin blockade may prolong virologic control by bNAbs in SHIVSF162P3-infected macaques.