Clinical and genetic factors associated with increased risk of severe liver toxicity in a monocentric cohort of HIV positive patients receiving nevirapine-based antiretroviral therapy

Background

Nevirapine has been used as antiretroviral agent since early ‘90. Although nevirapine is not currently recommended in initial anti-HIV regimens, its use remains consistent in a certain number of HIV-1-positive subjects. Thus, our aim was to determine clinical and genetic factors involved in the development of severe nevirapine induced liver toxicity.

Methods

We retrospectively analyzed all HIV positive patients who were followed at the Infectious Diseases Unit, DIBIC Luigi Sacco, University of Milan from May 2011 to December 2015. All patients treated with nevirapine who underwent a genotyping for the functional variants mapping into ABCB1, CYP2B6, CYP3A4 and CYP3A5 genes were included in the analysis. Severe hepatotoxicity was defined as ACTG grade 3–4 AST/ALT increase during the first three months of nevirapine treatment. The causality assessment between NVP exposure and drug-induced liver injury was performed by using the updated Roussel Uclaf Causality Assessment Methods. Hardy Weinberg equilibrium was tested by χ² test. A multivariable logistic regression model was constructed using a backward elimination method.

Results

Three hundred and sixty-two patients were included in the analysis, of which 8 (2.2%) experienced a severe liver toxicity. We observed no differences between patients with and without liver toxicity as regards gender, ethnicity, age and immune-virological status. A higher prevalence of HCV coinfection (75.0% vs 30.2%; p = .0013) and higher baseline AST (58 IU/L vs 26 IU/L; p = 0.041) and ALT (82 IU/L vs 27 IU/L; p = 0.047) median levels were observed in patients with liver toxicity vs those without toxicity. The genotypes CT/TT at ABCB1 rs1045642 single nucleotide polymorphism (SNP), showed a protective effect for liver toxicity when compared with genotype CC (OR = 0.18, 95%CI 0.04–0.76; p = 0.020) in univariate analysis. In the multivariate model, HCV coinfection was independently associated with higher risk of developing liver toxicity (aOR = 8.00, 95%CI 1.27–50.29; p = 0.027), whereas ABCB1 rs1045642 CT/TT genotypes (aOR = 0.10, 95%CI 0.02–0.47; p = 0.004) was associated with a lower risk.

Conclusions

According to our findings HCV coinfection and ABCB1 rs1045642 SNP represent independent determinants of severe liver toxicity related to nevirapine. This genetic evaluation could be included as toxicity assessment in HIV-1-positive subjects treated with nevirapine.

CD4+ T cell counts in initiation of antiretroviral therapy in HIV infected asymptomatic individuals; controversies and inconsistencies

The primary goal when devising strategies to define the start of therapy in HIV infected individuals is to avoid HIV disease progression and toxicity from antiretroviral therapy (ART). Intermediate goals includes, avoiding resistance by suppressing HIV replication, reducing transmission, limiting spread and diversity of HIV within the body and protecting the immune system from harm. The question of how early or late to start ART and achieve both primary and intermediate goals has dominated HIV research. The distinction between early and late treatment of HIV infection is currently a matter of CD4+ T cells count, a marker of immune status, rather than on viral load, a marker of virus replication. Discussions about respective benefits of early or delayed therapy, as well as the best CD4+ T cell threshold during the course of HIV infection at which ART is initiated remains inconclusive. Guidelines issued by various agencies, provide different initiation recommendations. This can be confusing for clinicians and policy-makers when determining the best time to initiate therapy. Optimizing ART initiation strategies are clearly complex and must be balanced between individual and broader public health needs. This review assesses available data that contributes to the debate on optimal time to initiate therapy in HIV-infected asymptomatic individuals. We also review reports on CD4+ T cell threshold to guide initiation of ART and finally discuss arguments for and against early or late initiation of ART.

Nevirapine-raltegravir combination, an NRTI and PI/r sparing regimen, as maintenance antiretroviral therapy in virologically suppressed HIV-1-infected patients

BACKGROUND

Nucleoside reverse transcriptase inhibitor (NRTI) and protease inhibitor (PI)/ritonavir sparing regimens may be useful to some HIV-infected patients. Nevirapine (NVP) and raltegravir (RAL) are both potent antiretrovirals with good long-term safety profiles.

METHODS

We retrospectively identified from our electronic database all patients with HIV RNA<50 copies/ml for >6 months on an NVP-containing regimen and no prior exposure to integrase strand transfer inhibitors who were switched to RAL plus NVP. Data was collected for 36 months or until discontinuation of RAL plus NVP for any reason.

RESULTS

A total of 39 patients (30 male) were included in this analysis. Median duration of prior antiretroviral therapy was 14 years (IQR 10-17) and median duration with plasma HIV-1 RNA<50 copies/ml prior to switch was 50 months (IQR 22-96). Switched regimens included mainly a boosted PI (n=24) or tenofovir disoproxil fumarate/emtricitabine (n=12). After switching, the percentages of patients with HIV-1 RNA<50 copies/ml were 87.2% (95% CI 76.7, 97.7) and 82.1% (95% CI 70.0, 94.1) at 6 and 12 months, respectively, in the intent-to-treat-exposed analysis, 97.1% (95% CI 91.6, 100) and 94.1% (95% CI 86.2, 100), respectively, in the per-protocol analysis. All patients with follow-up to month 24 (n=22) or month 36 (n=14) had HIV-1 RNA<50 copies/ml. One virological failure was observed (related to archived non-nucleoside reverse transcriptase inhibitor resistance mutation). During follow-up, no patient experienced Grade 3 or 4 adverse events. Median values of serum creatinine and lipids significantly improved after switch.

CONCLUSIONS

In patients with prolonged HIV-1 RNA<50 copies/ml, switching to NVP-RAL combination maintained virological suppression throughout 36 months. This combination deserves further evaluation in patients unable to tolerate NRTI or PI/ritonavir agents.