Real-world use of long-acting cabotegravir and rilpivirine: 12-month results of the inJectable Antiretroviral therapy feasiBility Study (JABS)

OBJECTIVES

The inJectable Antiretroviral feasiBility Study (JABS) aimed to evaluate the implementation of long-acting regimens in a 'real world' Australian setting, with inclusion of participants with complex medical needs, social vulnerability and/or historical non-adherence.

METHODS

JABS was a 12-month, single-centre, single-arm, open-label phase IV study of long-acting cabotegravir 600 mg plus rilpivirine 900 mg administered intramuscularly every 2 months to adults with treated HIV-1 infection. The primary endpoint was the proportion of attendances and administration of injections within a 14-day dosing window over 12 months, out of the total prescribed doses. Secondary endpoints included proportions of missed appointments, use of oral bridging, discontinuations, virological failures, adverse events and participant-reported outcomes. A multidisciplinary adherence programme embedded in the clinical service known as REACH provided support to JABS participants.

RESULTS

Of 60 participants enrolled by May 2022, 60% had one or more complexity or vulnerability factors identified, including absence of social supports (50%), mental health issues, alcohol or drug use (30%) and financial hardship or instability (13%), among others. Twenty-seven per cent of participants had historical non-adherence to antiretroviral therapy. Out of 395 prescribed doses, 97.2% of injections were administered within correct dosing windows at clinic visits. Two courses of short-term oral bridging were required. The rate of injection site reactions was 29%, the majority being grade 1-2. There were no virological failures, no serious adverse events and only one injection-related study discontinuation. High baseline treatment satisfaction and acceptability of injections increased by month 12. Those with vulnerability factors had similar adherence to injections as those without such factors. Ninety-eight per cent of the participants who completed 12 months on the study have maintained long-acting therapy, virological suppression and retention in care.

CONCLUSIONS

Long-acting cabotegravir plus rilpivirine was associated with very high adherence, maintenance of virological suppression, safety and treatment satisfaction in a diverse Australian clinic population, comparable to results of phase III randomized clinical trials. Individuals with vulnerability factors can achieve adherence to injections with individualized support. Long-acting therapies in this group can increase the subsequent engagement in clinical care.

Determinants of residual viraemia during combination HIV treatment: Impacts of baseline HIV RNA levels and treatment choice

OBJECTIVES

Effective HIV therapy reflects suppression of plasma HIV RNA levels below assay detection thresholds, although lower levels of "residual viraemia" have also been demonstrated over extended periods of effective antiretroviral treatment. Here we examine the determinants of HIV RNA suppression below the standard assay threshold (40 HIV-1 RNA copies/mL) as well as factors associated with detectable HIV RNA below this reported detection limit.

METHODS

Between 2007 and 2010, 11 575 consecutive viral load (VL) tests were obtained from 1540 patients, including 356 on effective antiretroviral therapy followed since initiation (1996-2001: n = 165; 2002-2009: n = 191). Analyses modelled the probability of an undetectable VL given successful suppression to < 200 copies/mL, and the probability of residual viraemia given an undetectable result.

RESULTS

Detectable HIV RNA amplification was demonstrated in 20% of samples with a VL result < 40 copies/mL. Longitudinal analyses from 356 patients revealed that the likelihood of achieving results < 40 copies/mL was increased with current nonnucleoside reverse transcriptase inhibitor (NNRTI) therapy [odds ratio (OR) 2.0; P < 0.05] and reduced with prior virological rebound (OR 0.5; P < 0.05). In contrast, the presence of detectable HIV RNA < 40 copies/mL was strongly associated with pretreatment HIV RNA levels among those on current protease inhibitor (PI) treatment (OR 1.5 per log10 copies/mL increase; P = 0.02) as well as those on NNRTIs (OR 1.7; P = 0.002).

CONCLUSIONS

While HIV treatment history was associated with plasma HIV RNA levels below the detection limit, residual viraemia results were dominantly determined by pretreatment VL. These findings support the concept of a stable, long-lived reservoir of latently infected cells as a source of residual viraemia despite effective HIV treatment.

Association between presence of HLA-B*5701, HLA-DR7, and HLA-DQ3 and hypersensitivity to HIV-1 reverse-transcriptase inhibitor abacavir

BACKGROUND

The use of abacavir--a potent HIV-1 nucleoside-analogue reverse-transcriptase inhibitor--is complicated by a potentially life-threatening hypersensitivity syndrome in about 5% of cases. Genetic factors influencing the immune response to abacavir might confer susceptibility. We aimed to find associations between MHC alleles and abacavir hypersensitivity in HIV-1-positive individuals treated with abacavir.

METHODS

MHC region typing was done in the first 200 Western Australian HIV Cohort Study participants exposed to abacavir. Definite abacavir hypersensitivity was identified in 18 cases, and was excluded in 167 individuals with more than 6 weeks' exposure to the drug (abacavir tolerant). 15 individuals experienced some symptoms but did not meet criteria for abacavir hypersensitivity. p values were corrected for comparisons of multiple HLA alleles (p(c)) by multiplication of the raw p value by the estimated number of HLA alleles present within the loci examined.

FINDINGS

HLA-B*5701 was present in 14 (78%) of the 18 patients with abacavir hypersensitivity, and in four (2%) of the 167 abacavir tolerant patients (odds ratio 117 [95% CI 29-481], p(c)<0.0001), and the HLA-DR7 and HLA-DQ3 combination was found in 13 (72%) of hypersensitive and five (3%) of tolerant patients (73 [20-268], p(c)<0.0001 ). HLA-B*5701, HLA-DR7, and HLA-DQ3 were present in combination in 13 (72%) hypersensitive patients and none of the tolerant patients (822 [43-15 675], p(c)<0.0001). Other MHC markers also present on the 57.1 ancestral haplotype to which the three markers above belong confirmed the presence of haplotype-specific linkage disequilibrium, and mapped potential susceptibility loci to a region bounded by C4A6 and HLA-C. Within the entire abacavir-exposed cohort (n=200), presence of HLA-B*5701, HLA-DR7, and HLA-DQ3 had a positive predictive value for hypersensitivity of 100%, and a negative predictive value of 97%.

INTERPRETATION

Genetic susceptibility to abacavir hypersensitivity is carried on the 57.1 ancestral haplotype. In our population, withholding abacavir in those with HLA-B*5701, HLA-DR7, and HLA-DQ3 should reduce the prevalence of hypersensitivity from 9% to 2.5% without inappropriately denying abacavir to any patient.