Protease inhibitor therapy in resource-limited settings

HIV multi-drug resistance at first-line antiretroviral failure and subsequent virological response in Asia

Introduction

First-line antiretroviral therapy (ART) failure often results from the development of resistance-associated mutations (RAMs). Three patterns, including thymidine analogue mutations (TAMs), 69 Insertion (69Ins) and the Q151M complex, are associated with resistance to multiple-nucleoside reverse transcriptase inhibitors (NRTIs) and may compromise treatment options for second-line ART.

Methods

We investigated patterns and factors associated with multi-NRTI RAMs at first-line failure in patients from The TREAT Asia Studies to Evaluate Resistance – Monitoring study (TASER-M), and evaluated their impact on virological responses at 12 months after switching to second-line ART. RAMs were compared with the IAS-USA 2013 mutations list. We defined multi-NRTI RAMs as the presence of either Q151M; 69Ins; ≥2 TAMs; or M184V+≥1 TAM. Virological suppression was defined as viral load (VL) <400 copies/ml at 12 months from switch to second-line. Logistic regression was used to analyze (1) factors associated with multi-NRTI RAMs at first-line failure and (2) factors associated with virological suppression after 12 months on second-line.

Results

A total of 105 patients from 10 sites in Thailand, Hong Kong, Indonesia, Malaysia and Philippines were included. There were 97/105 (92%) patients harbouring ≥1 RAMs at first-line failure, 39/105 with multi-NRTI RAMs: six with Q151M; 24 with ≥2 TAMs; and 32 with M184V+≥1 TAM. Factors associated with multi-NRTI RAMs were CD4 ≤200 cells/µL at genotyping (OR=4.43, 95% CI [1.59–12.37], p=0.004) and ART duration >2 years (OR=6.25, 95% CI [2.39–16.36], p<0.001). Among 87/105 patients with available VL at 12 months after switch to second-line ART, virological suppression was achieved in 85%. The median genotypic susceptibility score (GSS) for the second-line regimen was 2.00. Patients with ART adherence ≥95% were more likely to be virologically suppressed (OR=9.33, 95% CI (2.43–35.81), p=0.001). Measures of patient resistance to second-line ART, including the GSS, were not significantly associated with virological outcome.

Conclusions

Multi-NRTI RAMs at first-line failure were associated with low CD4 level and longer duration of ART. With many patients switching to highly susceptible regimens, good adherence was still crucial in achieving virological response. This emphasizes the importance of continued adherence counselling well into second-line therapy.

Factors associated with suboptimal adherence to antiretroviral therapy in Asia

INTRODUCTION

Adherence to antiretroviral therapy (ART) plays an important role in treatment outcomes. It is crucial to identify factors influencing adherence in order to optimize treatment responses. The aim of this study was to assess the rates of, and factors associated with, suboptimal adherence (SubAdh) in the first 24 months of ART in an Asian HIV cohort.

METHODS

As part of a prospective resistance monitoring study, the TREAT Asia Studies to Evaluate Resistance Monitoring Study (TASER-M) collected patients' adherence based on the World Health Organization-validated Adherence Visual Analogue Scale. SubAdh was defined in two ways: (i) <100% and (ii) <95%. Follow-up time started from ART initiation and was censored at 24 months, loss to follow-up, death, treatment switch, or treatment cessation for >14 days. Time was divided into four intervals: 0-6, 6-12, 12-18 and 18-24 months. Factors associated with SubAdh were analysed using generalized estimating equations.

RESULTS

Out of 1316 patients, 32% ever reported <100% adherence and 17% ever reported <95%. Defining the outcome as SubAdh <100%, the rates of SubAdh for the four time intervals were 26%, 17%, 12% and 10%. Sites with an average of >2 assessments per patient per year had an odds ratio (OR)=0.7 (95% confidence interval (CI) (0.55 to 0.90), p=0.006), compared to sites with ≤2 assessments per patient per year. Compared to heterosexual exposure, SubAdh was higher in injecting drug users (IDUs) (OR=1.92, 95% CI (1.23 to 3.00), p=0.004) and lower in homosexual exposure (OR=0.52, 95% CI (0.38 to 0.71), p<0.001). Patients taking a nucleoside transcriptase inhibitor and protease inhibitor (NRTI+PI) combination were less likely to report adherence <100% (OR=0.36, 95% CI (0.20 to 0.67), p=0.001) compared to patients taking an NRTI and non-nucleoside transcriptase inhibitor (NRTI+NNRTI) combination. SubAdh decreased with increasing time on ART (all p<0.001). Similar associations were found with adherence <95% as the outcome.

CONCLUSIONS

We found that SubAdh, defined as either <100% and <95%, was associated with mode of HIV exposure, ART regimen, time on ART and frequency of adherence measurement. The more frequently sites assessed patients, the lower the SubAdh, possibly reflecting site resourcing for patient counselling. Although social desirability bias could not be excluded, a greater emphasis on more frequent adherence counselling immediately following ART initiation and through the first six months may be valuable in promoting treatment and programme retention.

A dimeric high-molecular-weight chymotrypsin inhibitor with antitumor and HIV-1 reverse transcriptase inhibitory activities from seeds of Acacia confusa

A dimeric 70-kDa chymotrypsin inhibitor with substantial N-terminal sequence homology to serine protease inhibitors was isolated from Acacia confusa seeds. The chymotrypsin inhibitor was purified using a protocol that entailed ion exchange chromatography on Q-Sepharose, SP-Sepharose and fast protein liquid chromatography-gel filtration on Superdex 75. The chymotrypsin inhibitor was unadsorbed on both Q-Sepharose and SP-Sepharose. Its chymotrypsin inhibitory activity was stable from pH 3 to 10 and from 0 to 50 degrees C. It exerted antiproliferative activity toward breast cancer MCF-7 cells with an IC(50) of 10.7+/-4.2 microM. It inhibited HIV-1 reverse transcriptase with an IC(50) of 8+/-1.5 microM. It was devoid of antifungal activity toward a variety of fungal species. The distinctive features of the chymotrypsin inhibitor included dimeric nature, a high molecular mass, lack of trypsin inhibitory activity, highly potent HIV-1 reverse transcriptase inhibitory activity, specific antitumor activity and relatively high pH-stability.

Resistance considerations in sequencing of antiretroviral therapy in low-middle income countries with currently available options

PURPOSE OF REVIEW

Access to antiretroviral therapy (ART) has been scaled-up in low-middle income countries (LMICs), where the majority of the world's HIV-1-infected population is living. Concerns towards the emergence and spread of HIV-1 drug resistance exist, given the lack of virological monitoring which may give rise to accumulation of resistance as well as the use of suboptimal ART in pregnant women with the aim to reduce perinatal transmission. Knowledge of the prevalence of transmitted and emerging drug resistance as well as its specific patterns is of help in guiding the selection of appropriate ART types and sequencing strategies.

RECENT FINDINGS

Whereas transmitted drug resistance in LMIC is still limited, resistance in pregnant women as a consequence of suboptimal ART for the prevention of vertical transmission is frequent and dependent on viral subtype and load. Accumulation of drug resistance during first-line ART depends on the frequency of monitoring, whereas mutational patterns are influenced by type of ART and, partly, viral subtype.

SUMMARY

Optimized ART for prevention of mother-to-child transmission and closer monitoring of ART programs with the inclusion of viral load may help reducing unnecessary development of HIV drug resistance in LMIC and preserve the limited available treatment options.

Current and Novel Inhibitors of HIV Protease

The design, development and clinical success of HIV protease inhibitors represent one of the most remarkable achievements of molecular medicine. This review describes all nine currently available FDA-approved protease inhibitors, discusses their pharmacokinetic properties, off-target activities, side-effects, and resistance profiles. The compounds in the various stages of clinical development are also introduced, as well as alternative approaches, aiming at other functional domains of HIV PR. The potential of these novel compounds to open new way to the rational drug design of human viruses is critically assessed.