Frequency of capsid substitutions associated with GS-6207 in vitro resistance in HIV-1 from antiretroviral-naive and -experienced patients

Background: GS-6207 is a first-in-class HIV capsid inhibitor, targeting several functions of the HIV capsid in the viral cycle, including viral particle assembly, capsid formation and nuclear entry. GS-6207 has demonstrated picomolar potency in vitro, activity confirmed by high potency in a Phase 1 clinical study, with a long-acting antiretroviral profile with potential dosing every 6months. In vitro resistance selections previously conducted with increasing doses of GS-6207 have identified capsid variants with reduced susceptibility to GS-6207. Objectives: To study the prevalence of capsid mutations associated with in vitro resistance to GS-6207 in people living with HIV (PLWH). Methods: Plasma samples from ART-naive or -experienced PLWH, including PI-experienced people, were sequenced and analysed for the presence of capsid variants identified during in vitro resistance selection: L56I, M66I, Q67H, K70N, N74D, N74S and T107N. Results: Among the samples from the 1500 patients studied, none of the seven GS-6207 resistance mutations identified during in vitro selection experiments was detected, regardless of HIV subtype or PLWH treatment history. Conclusions: Out of the seven HIV capsid substitutions previously selected in vitro and shown to confer phenotypic resistance to GS-6207, none of these seven mutations was observed in this large dataset, suggesting that neither PLWH with previous PI failure nor PLWH with emergence of PI resistance mutations are anticipated to impact GS-6207 activity in these diverse HIV-infected populations.