Pharmacokinetic and pharmacokinetic/pharmacodynamic characterization of the dolutegravir/rilpivirine two-drug regimen in SWORD-1/-2 phase 3 studies.

AIM: SWORD-1 and SWORD-2 phase 3 studies concluded that switching virologically suppressed participants with HIV-1 from their current three- or four-drug antiretroviral regimen (CAR) to the two-drug regimen of once-daily dolutegravir (DTG, 50 mg) and rilpivirine (RPV, 25 mg) was safe, well tolerated and noninferior for maintaining HIV-1 suppression at week 48 and highly efficacious to week 148. A secondary objective was to characterize drug exposure and exposure-efficacy/safety relationships. METHODS: Adults with plasma HIV-1 RNA <50 copies/mL were randomized to switch to once-daily DTG + RPV on day 1 or to continue CAR for 52 weeks before switching. Trough plasma concentrations (C0) of DTG and RPV, the proportion of participants with HIV-1 RNA <50 copies/mL and adverse events to week 100 were summarized and subjected to exposure-response analyses in the overall population, in the subset of participants who switched from CAR containing enzyme-inducing drugs and by age category (≥50 and <50 years). The relationship between C0avg (individual average C0 across visits) and efficacy/safety was investigated. RESULTS: Although week 2 DTG and RPV C0 were lower in participants switching from enzyme-inducing antiretroviral drugs, C0 and C0avg stayed above in vitro antiviral protein binding-adjusted IC90 and to week 100 with viral suppression >89%. DTG or RPV C0avg showed no relationship with virologic failures or safety. Participants ≥50 years had similar C0avg and safety response to younger participants. CONCLUSION: No clinically relevant relationship between DTG or RPV exposures and virologic or safety response was observed, confirming the DTG + RPV switch for participants as a safe and effective treatment.

Role of interferon regulatory factor-1 in double-stranded RNA-induced iNOS expression by mouse islets.

Environmental factors, such as viral infection, have been implicated as potential triggering events leading to the initial destruction of pancreatic beta cells during the development of autoimmune diabetes. Double-stranded RNA (dsRNA), the active component of a viral infection that stimulates antiviral responses in infected cells, has been shown in combination with interferon-gamma (IFN-gamma) to stimulate inducible nitric oxide synthase (iNOS) expression and nitric oxide production and to inhibit beta cell function. Interferon regulatory factor-1 (IRF-1), the activation of which is induced by dsRNA, viral infection, and IFN-gamma, regulates the expression of many antiviral proteins, including PKR, type I IFN, and iNOS. In this study, we show that IRF-1 is not required for dsRNA + IFN-gamma-stimulated iNOS expression and nitric oxide production by mouse islets. In contrast to islets, dsRNA + IFN-gamma fails to induce iNOS expression or nitric oxide production by macrophages isolated from IRF-1(-/-) mice; however, dsRNA + IFN-gamma induces similar levels of IL-1 release by macrophages isolated from both IRF-1(-/-) and IRF-1(+/+) mice. Importantly, we show that dsRNA- or dsRNA + IFN-gamma-stimulated IRF-1 expression by mouse islets and peritoneal macrophages is independent of PKR. These results indicate that IRF-1 is required for dsRNA + IFN-gamma-induced iNOS expression and nitric oxide production by mouse peritoneal macrophages but not by mouse islets. These findings suggest that dsRNA + IFN-gamma stimulates iNOS expression by two distinct PKR-independent mechanisms; one that is IRF-1-dependent in macrophages and another that is IRF-1-independent in islets.