Injectable Antiretroviral Drugs: Back to the Future

Pharmacological advances in anti-retroviral therapy for human immunodeficiency virus-1 infection: A comprehensive review

The discovery of anti-retroviral (ARV) drugs over the past 36 years has introduced various classes, including nucleoside/nucleotide reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, protease inhibitor, fusion, and integrase strand transfer inhibitors inhibitors. The introduction of combined highly active anti-retroviral therapies in 1996 was later proven to combat further ARV drug resistance along with enhancing human immunodeficiency virus (HIV) suppression. As though the development of ARV therapies was continuously expanding, the variation of action caused by ARV drugs, along with its current updates, was not comprehensively discussed, particularly for HIV-1 infection. Thus, a range of HIV-1 ARV medications is covered in this review, including new developments in ARV therapy based on the drug's mechanism of action, the challenges related to HIV-1, and the need for combination therapy. Optimistically, this article will consolidate the overall updates of HIV-1 ARV treatments and conclude the significance of HIV-1-related pharmacotherapy research to combat the global threat of HIV infection.

Is the Central Nervous System Reservoir a Hurdle for an HIV Cure?

There is currently no cure for HIV infection although adherence to effective antiretroviral therapy (ART) suppresses replication of the virus in blood, increases CD4+ T-cell counts, reverses immunodeficiency, and increases life expectancy. Despite these substantial advances, ART is a lifelong treatment for people with HIV (PWH) and upon cessation or interruption, the virus quickly rebounds in plasma and anatomic sites, including the central nervous system (CNS), resulting in disease progression. With recent advances in quantifying viral burden, detection of genetically intact viral genomes, and isolation of replication-competent virus from brain tissues of PWH receiving ART, it has become apparent that the CNS viral reservoir (largely comprised of macrophage type cells) poses a substantial challenge for HIV cure strategies. Other obstacles impacting the curing of HIV include ageing populations, substance use, comorbidities, limited antiretroviral drug efficacy in CNS cells, and ART-associated neurotoxicity. Herein, we review recent findings, including studies of the proviral integration sites, reservoir decay rates, and new treatment/prevention strategies in the context of the CNS, together with highlighting the next steps for investigations of the CNS as a viral reservoir.

Long-Term Effectiveness of Rilpivirine-Based Single-Tablet Regimens in a Seven-Year, Two-Center Observational Cohort of People Living with HIV

Data on the long-term durability of rilpivirine (RPV) are still scarce. A two-center retrospective study was performed, including all people living with HIV (PLWH) treated with tenofovir disoproxil fumarate/emtricitabine (TDF/FTC)/RPV or tenofovir alafenamide (TAF)/FTC/RPV in the period January 2013-December 2019. Aims of the study were to assess the rate of discontinuation of the RPV single-tablet regimen (STR) and identify factors associated with the risk of discontinuation according to Cox's regression analysis. A total of 684 PLWH were enrolled. Mean duration of RPV-STR treatment was 192.5 (±99.5) weeks for 123 antiretroviral therapy (ART)-naïve participants (18%) and 173.3 (± 85.6) weeks for 561 ART-experienced study participants (82%). During the study period, the incidence of discontinuation was 7.7 per 100 person-years. The estimated proportions of discontinuation after 48 and 96 weeks were 5.6% and 13.4%, respectively. Causes of discontinuation were loss to follow-up (30%), side effects (15%), ART optimization (14%), virological failure (VF) (12%), death or transfer to another center (9%), low adherence (7%), drug interactions (6%), simplification to dual therapy (3%), and unknown (3%). No differences were observed in cumulative probability of discontinuation between ART-naïve and -experienced PLWH. Heterosexual (hazard ratio [HR] 3.0, 95% confidence interval [CI] 1.4-6.8) and mother-to-child (HR 5.3, 95% CI 1.8-15.3) transmission of HIV infection and history of previous VF (HR 1.7, 95% CI 1.2-2.5) were associated with higher risk of discontinuation. High RPV-STR effectiveness and durability were confirmed in our real-life population of PLWH. Given these data, RPV has the potential to be a drug for life in patients selected according to current guidelines.

Enhanced Antiviral Ability by a Combination of Zidovudine and Short Hairpin RNA Targeting Avian Leukosis Virus

Avian leukosis virus (ALV) causes tumor diseases in poultry and is circulating all over the world, leading to significant economic losses. In addition, mixed infection of ALV with other viruses is very common and is often reported to contaminate live vaccines. At present, there is no effective method to suppress the replication of ALV in vitro, so it is very difficult to remove it in mixed infection. As a retrovirus, the replication of ALV can be limited by reverse transcriptase (RT) inhibitors like zidovudine (AZT), but it also causes nontargeted cytotoxicity. To find the optimal solution in cytotoxicity and inhibition efficiency in vitro culture system, we firstly designed a combination therapy of AZT and short hairpin RNA (shRNA) targeting ALV and then verified its efficiency by multiple biological methods. Results showed that shRNA can effectively inhibit the expression of RT and then limit the replication of ALV. The combination of AZT and shRNA can significantly improve the antiviral efficiency in viral replication, shedding, and provirus assembly under the condition of low cytotoxicity. Overall, in this study, the combination therapy of AZT and shRNA targeting ALV showed excellent antiviral performance against ALV in vitro culture system. This method can be applied to multiple scenarios, such as the removal of ALV in mixed infection or the purification of contaminated vaccine strains.

Could Long-Acting Cabotegravir-Rilpivirine Be the Future for All People Living with HIV? Response Based on Genotype Resistance Test from a Multicenter Italian Cohort

Long-acting (LA) formulations have been designed to improve the quality of life of people with HIV (PWH) by maintaining virologic suppression. However, clinical trials have shown that patient selection is crucial. In fact, the HIV-1 resistance genotype test and the Body Mass Index of individual patients assume a predominant role in guiding the choice. Our work aimed to estimate the patients eligible for the new LA therapy with cabotegravir (CAB) + rilpivirine (RPV). We selected, from the Antiviral Response Cohort Analysis (ARCA) database, all PWH who had at least one follow-up in the last 24 months. We excluded patients with HBsAg positivity, evidence of non-nucleoside reverse transcriptase inhibitor (except K103N) and integrase inhibitor mutations, and with a detectable HIV-RNA (>50 copies/mL). Overall, 4103 patients are currently on follow-up in the ARCA, but the eligible patients totaled 1641 (39.9%). Among them, 1163 (70.9%) were males and 1399 were Caucasian (85.3%), of which 1291 (92%) were Italian born. The median length of HIV infection was 10.2 years (IQR 6.3–16.3) with a median nadir of CD4 cells/count of 238 (106–366) cells/mm³ and a median last available CD4 cells/count of 706 (509–944) cells/mm³. The majority of PWH were treated with a three-drug regimen (n = 1116, 68%). Among the 525 (30.3%) patients treated with two-drug regimens, 325 (18.1%) were treated with lamivudine (3TC) and dolutegravir (DTG) and only 84 (5.1%) with RPV and DTG. In conclusion, according to our snapshot, roughly 39.9% of virologically suppressed patients may be suitable candidates for long-acting CAB+RPV therapy. Therefore, based on our findings, many different variables should be taken into consideration to tailor the antiretroviral treatment according to different individual characteristics.

Tolerability and Adherence of Antiretroviral Regimens Containing Long-Acting Fusion Inhibitor Albuvirtide for HIV Post-Exposure Prophylaxis: A Cohort Study in China

INTRODUCTION

There have been no prospective clinical studies investigating adherence and tolerability of HIV post-exposure prophylaxis (PEP) in China. Tolerability, adherence, and transmitted drug resistance are concerns, especially when single-tablet regimen (STR) usage is low. The present study aimed to explore the safety, tolerability, and adherence of regimens containing albuvirtide (ABT) compared with recommended non-STR antiretrovirals for HIV PEP.

METHODS

This was a prospective, open-label, multicenter cohort study. The subjects were stratified into 3 groups based on their preference: ABT + Dolutegravir (DTG) (Group 1), ABT + Tenofovir disoproxil fumarate (TDF) + Lamivudine (3TC) (Group 2), and DTG + TDF + 3TC (Group 3). All enrolled subjects received PEP within 72 h after exposure and continued for 28 days, and were followed-up for 12 weeks.

RESULTS

A total of 330 participants were enrolled in the three groups. Most participants were male (87.2%). Sexual contact was the most frequent mode of exposure (91.9%). The average time from exposure to treatment was 26.8 ± 19.5 h. There were no statistically significant differences between the three study groups with respect to completion of oral medication at 28 days. The 28-day completion rate was shown to be significantly higher with ABT versus oral (88.9% vs. 64.0%; p < 0.0001), and adherence with ABT was 94.4% compared to 75.7% with oral PEP (p < 0.0001). Subjects in ABT-containing Group 1 exhibited higher adherence than those in Group 3 (87.3% vs. 72.9%; p < 0.05). None of the participants reported serious adverse drug reactions which led to withdrawal from the study. All the drug regimens were found to be safe and well tolerated. No HIV incident case was observed during the study period.

CONCLUSIONS

ABT-containing regimens (ABT + DTG or ABT + TDF + 3TC) offer a good option for HIV PEP due to higher completion rates and adherence than the DTG + TDF + 3TC regimen. The overall safety was comparable and acceptable among the three groups.

REGISTRATION

The study was registered in Chinese Clinical Trial Registry with registration number (ChiCTR1900022881, http://www.chictr.org.cn/showprojen.aspx?proj=37395 ).

Evaluating fostemsavir as a therapeutic option for patients with HIV

ABSTRACIntroduction: Despite the unquestionable success of antiretroviral therapy achieved in recent years, there are still cases of heavily treated patients who do not achieve or struggle to maintain undetectable HIV-RNA due to drug resistance. New antiretroviral options are needed to address this issue.Area covered: The authors first provide an overview of fostemsavir and its role in the treatment of HTE PLWH. Data from pre-clinical and clinical studies are reviewed and the pharmacokinetic and farmacodynamic properties are highlited. Drug-drug interactions and safety data from available clinical studies are also discussed.Expert opinion: Fostemsavir is a promising antiretroviral belonging to the class of entry inhibitors; its novel mechanism of action represents a very important innovation. Its use will be limited to the heavy-treatment-experienced patient population. This use will have to be monitored to avoid abuse and waste of a molecule that for some patients may represent a life-saving drug.