WG-am combinations restore antiviral potency against fostemsavir and lenacapavir-resistant HIV-1

BACKGROUND: Resistance to fostemsavir (FTR) and lenacapavir (LEN) poses critical challenges for heavily treatment-experienced (HTE) people with HIV-1 who have exhausted conventional therapeutic options. We evaluated the antiviral synergy of tryptophylglycine-amide (WG-am), a naturally occurring dipeptide from HIV-1 elite controllers that inhibits viral entry and reverse transcription, in combination with seven antiretrovirals against FTR- and LEN-resistant HIV-1 viruses. METHODS: Combination assays were performed in TZM-bl cells using a 7×7 dose-matrix format against nine HIV-1 viruses with defined FTR- or LEN-resistance mutations. Synergy was quantified using the zero-interaction potency (ZIP) model in SynergyFinder across all concentrations and at the ≥90% viral inhibition threshold. Three priority combinations - with ibalizumab (IBA), darunavir (DRV), and FTR - were validated in activated PBMCs from three independent donors. RESULTS: WG-am demonstrated synergistic or additive interactions with all seven antiretrovirals; no antagonism was detected. IBA and DRV showed the highest and most consistent synergy across both resistance backgrounds. FTR showed paradoxical synergy against FTR-resistant virus (peak ZIP 15.58 against S375T). At the ≥90% inhibition threshold, 87.3% (55/63) of combination pairs were synergistic. PBMC validation confirmed synergy for all six priority combinations (ZIP 11.01-17.19), with WG-am + FTR scores exceeding TZM-bl values in primary cells. CONCLUSIONS: WG-am-based combinations demonstrate synergistic antiviral activity against FTR- and LEN-resistant HIV-1 in reporter cells and primary immune cells. IBA, DRV, and FTR are identified as priority combination partners for WG-am as a component of resistance-informed salvage regimens for HTE patients with limited treatment options.