Factors influencing the efficacy of rilpivirine in HIV-1 subtype C in low- and middle-income countries

Abstract

Objectives: The use of the NNRTI rilpivirine in low- and middle-income countries (LMICs) is under debate. The main objective of this study was to provide further clinical insights and biochemical evidence on the usefulness of rilpivirine in LMICs.

Patients and methods: Rilpivirine resistance was assessed in 5340 therapy-naive and 13,750 first-generation NNRTI-failed patients from Europe and therapy-naive HIV-1 subtype C (HIV-1C)-infected individuals from India (n = 617) and Ethiopia (n = 127). Rilpivirine inhibition and binding affinity assays were performed using patient-derived HIV-1C reverse transcriptases (RTs).

Results: Primary rilpivirine resistance was rare, but the proportion of patients with >100,000 HIV-1 RNA copies/mL pre-ART was high in patients from India and Ethiopia, limiting the usefulness of rilpivirine as a first-line drug in LMICs. In patients failing first-line NNRTI treatments, cross-resistance patterns suggested that 73% of the patients could benefit from switching to rilpivirine-based therapy. In vitro inhibition assays showed ∼ 2-fold higher rilpivirine IC50 for HIV-1C RT than HIV-1B RT. Pre-steady-state determination of rilpivirine-binding affinities revealed 3.7-fold lower rilpivirine binding to HIV-1C than HIV-1B RT. Structural analysis indicated that naturally occurring polymorphisms close to the NNRTI-binding pocket may reduce rilpivirine binding, leading to lower susceptibility of HIV-1C to rilpivirine.

Conclusions: Our clinical and biochemical findings indicate that the usefulness of rilpivirine has limitations in HIV-1C-dominated epidemics in LMICs, but the drug could still be beneficial in patients failing first-line therapy if genotypic resistance testing is performed.

Figure 1.

Primary resistance and cross-resistance to rilpivirine and pre-therapy HIV-1 RNA load. (a) Primary resistance to rilpivirine using Stanford HIVDB version 7.0.1. (b) Subtype-tailored HIV-1 plasma RNA load (log₁₀ copies/mL) at initiation of ART measured using Cobas Amplicor HIV-1 monitor v1.5, Cobas TaqMan HIV-1 v1.0 or Cobas TaqMan HIV-1 v2.0 (Roche Molecular Systems, Basel, Switzerland) for the Swedish cohort or the Abbott m2000rt real-time PCR system (Abbott, Germany) for the Indian and Ethiopian cohorts. The percentages of treatment-naive patients with an HIV-1 RNA load of >100 000 copies/mL at initiation of ART are indicated. (c) Cross-resistance to rilpivirine in the EuResist database using Stanford HIVDB version 7.0.1. Among the 13 750 sequences obtained, 12 297 (89%) passed quality control as per the Stanford database and were thus included in the analysis. (d) Rilpivirine DRM profiles. *Significant difference (P < 0.05). This figure appears in colour in the online version of JAC and in black and white in the print version of JAC.

Figure 2.

(a) Inhibition of RT activity. The HIV-1B clones were pNL4-3, BH10 and HXB2 and the selected HIV-1C sequences were based on WGS of HIV-1C isolated from four patients. None of the sequences had documented rilpivirine mutations. **P < 0.05 and *borderline significance (P = 0.05) compared with pNL4-3. (b and c) Determination of K_d.RPV of WT HIV-1C and HIV-1B RTs. Single nucleotide (dATP) incorporation assays were performed under pre-steady-state conditions to determine K_d.RPV. (d) Structural comparison of rilpivirine binding and residues at the interface between thumb and connection subdomains in HIV-1B and HIV-1C RTs. This figure shows an example of differences in amino acid residues at the interface of thumb and connection subdomains of HIV-1B (turquoise) and HIV-1C (pink) RTs. The change in the conformation of R277 between HIV-1B and HIV-1C RTs is marked with a red arrow. The dotted lines show the hydrogen bond interactions in HIV-1B RT. RPV, rilpivirine. This figure appears in colour in the online version of JAC and in black and white in the print version of JAC.