Acquisition of Multidrug-Resistant Human Immunodeficiency Virus Type 1 Infection in a Patient Taking Preexposure Prophylaxis

First Case of HIV Seroconversion With Integrase Resistance Mutations on Long-Acting Cabotegravir for Prevention in Routine Care

Background

Long-acting cabotegravir (CAB-LA) is highly effective for HIV prevention, but delayed HIV diagnoses and integrase strand transfer inhibitor (INSTI) resistance were observed in trials. We report the first case in routine clinical care of HIV infection on CAB-LA with INSTI resistance.

Methods

The SeroPrEP study enrolls individuals in the United States who acquire HIV on pre-exposure prophylaxis modalities to assess diagnostics, antiretroviral (ARV) drug levels, resistance, and treatment outcomes. Resistance mutations in full-length HIV-1 integrase were identified by single-genome sequencing (SGS). Cabotegravir concentrations in plasma and hair segments were measured by liquid chromatography-tandem mass spectrometry.

Results

A 23-year-old gender-nonbinary person, male at birth, restarted CAB-LA 6 months after discontinuation due to losing insurance. Prior to restart, HIV-1 RNA was not detected, but 20 days elapsed before CAB-LA injection. After the second CAB-LA injection, HIV antigen/antibody returned reactive (HIV-1 RNA 451 copies/mL). SGS of plasma HIV-1 RNA identified INSTI mutation Q148R in 2/24 sequences 2 days postdiagnosis; commercial genotype failed amplification. Cabotegravir hair concentration was 0.190 ng/mg 2 weeks prediagnosis; plasma cabotegravir was high (3.37 μg/mL; ∼20× PA-IC90) 14 days postdiagnosis. Viral suppression was maintained for 6 months on darunavir/cobicistat/emtricitabine/tenofovir alafenamide, then switched to doravirine + emtricitabine/tenofovir alafenamide due to nausea.

Conclusions

In this first case of HIV infection on CAB-LA with INSTI resistance in routine care, cabotegravir resistance was detected only with a sensitive research assay. Accelerated pathways to minimize time between HIV testing and CAB-LA initiation are needed to optimize acute HIV detection and mitigate resistance risk. Sustained product access regardless of insurance is imperative to reduce HIV infections on CAB-LA.

Breakthrough Acute HIV Infections among Pre-Exposure Prophylaxis Users with High Adherence: A Narrative Review

Pre-exposure prophylaxis (PrEP) is a pivotal intervention among HIV prevention strategies. We aimed to narratively revise the topic of HIV acute infection in the setting of PrEP exposure with a focus on diagnostic options, clinical features, and future PrEP perspectives, with a particular focus on users with high adherence to PrEP. We searched the main databases (PubMed, Embase, and Scopus) with the keywords "PrEP" or "Pre-Exposure Prophylaxis" and "HIV" or "PLWH" and "breakthrough" or "acute infection" or "primary infection". We included all randomized clinical trials and non-experimental studies (both case reports and observational studies) ever published. In the present narrative review, we revise the diagnostic challenges related to HIV diagnosis in the setting of PrEP and the clinical characteristics and symptoms of breakthrough infections. We discuss the management of acute HIV infection during PrEP and the new challenges that arise from the use of long-acting drugs for PrEP. Our review underlines that although extremely rare, HIV seroconversions are still possible during PrEP, even in a context of high adherence. Efforts to promptly identify these events must be included in the PrEP follow-up in order to minimize the chance of overlooked HIV breakthrough infections and thus exposure to suboptimal concentrations of antiretrovirals.

Virological safety of the UK blood supply in the era of individual risk assessments and HIV PrEP

A more individualised donor selection policy was implemented in the UK in 2021, which replaced the previous 3-month deferral for men who have sex with men (MSM). Other blood services have a variety of policies in place to ensure the virological safety of blood components, ranging from an indefinite ban on MSM, to a defined period of exclusion, or to an individualised risk assessment that is not based on gender or sexual orientation. Justification of these policies should be based on scientific evidence including assessment of lengths of virological window periods, infectious disease epidemiology within donor populations and donation screening assay sensitivities. Developments in molecular technology and assays which can detect both antibodies and antigens in the very early stages of infection have significantly reduced the risk in most developed countries. However, the increasing usage of pre-exposure prophylaxis (PrEP) to prevent acquisition of HIV infection after possible high-risk sexual contact within the UK blood donor population has been recently noted. It has brought with it new diagnostic challenges within blood screening, notably possible non-detection of HIV RNA and serological markers following PrEP use despite potential infectivity. The use of other testing strategies such as detection of HIV DNA and screening for non-declared PrEP usage should be investigated further.

Clinical Considerations in the Selection of Preexposure Prophylaxis for HIV Prevention in Canada

According to the Public Health Agency of Canada, approximately 62,050 people were living with HIV in Canada in 2018, and of those, 13% were undiagnosed. Currently, no single strategy provides complete protection or is universally effective across all demographic groups at risk for HIV. However, HIV preexposure prophylaxis (PrEP) is the newest HIV prevention strategy that shows promise. To date, two products have received an indication for PrEP by Health Canada: emtricitabine/tenofovir disoproxil fumarate (Truvada®; FTC/TDF) and emtricitabine/tenofovir alafenamide (Descovy®; FTC/TAF). Despite the high efficacy of these PrEP intervention methods, access to PrEP in Canada remains low. Identifying and addressing barriers to PrEP access, especially in high-risk groups, are necessary to reduce HIV transmission in Canada. While guidelines published by the Center for Disease Control and Prevention (CDC) include FTC/TAF information, the efficacy of FTC/TAF for PrEP has not yet been considered in Canada's clinical practice guidelines. Thus, the current paper reviews data regarding the use of FTC/TDF and FTC/TAF for PrEP, which may be useful for Canadian healthcare providers when counseling and implementing HIV prevention methods. The authors highlight these data in relation to various at-risk populations and review ongoing clinical trials investigating novel PrEP agents. Overall, FTC/TDF PrEP is effective for many populations, including men who have sex with men, transgender women, heterosexuals with partners living with HIV, and people who use drugs. While there is fewer data reported on the efficacy of FTC/TAF to date, recent clinical trials have demonstrated noninferiority of FTC/TAF in comparison to FTC/TDF. Notably, as studies have shown that FTC/TAF maintains renal function and bone mineral density to a greater extent than FTC/TDF, FTC/TAF may be a safer option for patients experiencing renal and/or bone dysfunction, for those at risk of renal and bone complications, and for those who develop FTC/TDF-related adverse events.

How could HIV-1 drug resistance impact preexposure prophylaxis for HIV prevention?

PURPOSE OF REVIEW

To review current laboratory and clinical data on the frequency and relative risk of drug resistance and range of mutations selected from approved and investigational antiretroviral agents used for preexposure prophylaxis (PrEP) of HIV-1 infection, including tenofovir disproxil fumarate (TDF)-based oral PrEP, dapivirine ring, injectable cabotegravir (CAB), islatravir, lenacapavir and broadly neutralizing antibodies (bNAbs).

RECENT FINDINGS

The greatest risk of HIV-1 resistance from PrEP with oral TDF/emtricitabine (FTC) or injectable CAB is from starting or continuing PrEP after undiagnosed acute HIV infection. By contrast, the dapivirine intravaginal ring does not appear to select nonnucleoside reverse transcriptase inhibitor resistance in clinical trial settings. Investigational inhibitors including islatravir, lenacapavir, and bNAbs are promising for use as PrEP due to their potential for sustained delivery and low risk of cross-resistance to currently used antiretrovirals, but surveillance for emergence of resistance mutations in more HIV-1 gene regions (gag, env) will be important as the same drugs are being developed for HIV therapy.

SUMMARY

PrEP is highly effective in preventing HIV infection. Although HIV drug resistance from PrEP use could impact future options in individuals who seroconvert on PrEP, the current risk is low and continued monitoring for the emergence of resistance and cross-resistance during product development, clinical studies, and product roll-out is advised to preserve antiretroviral efficacy for both treatment and prevention.

Evidence and implication of interventions across various socioecological levels to address pre-exposure prophylaxis uptake and adherence among men who have sex with men in the United States: a systematic review

BACKGROUND

Pre-exposure prophylaxis (PrEP) represents a proven biomedical strategy to prevent HIV transmissions among men who have sex with men (MSM) in the United States (US). Despite the design and implementation of various PrEP-focus interventions in the US, aggregated evidence for enhancing PrEP uptake and adherence is lacking. The objective of this systematic review is to synthesize and evaluate interventions aimed to improve PrEP uptake and adherence among MSM in the US, and identify gaps with opportunities to inform the design and implementation of future PrEP interventions for these priority populations.

METHODS

We followed the PRISMA guidelines and conducted a systematic review of articles (published by November 28, 2021) with a focus on PrEP-related interventions by searching multiple databases (PubMed, MEDLINE, Web of Science and PsycINFO). Details of PrEP interventions were characterized based on their socioecological level(s), implementation modalities, and stage(s) of PrEP cascade continuum.

RESULTS

Among the 1363 articles retrieved from multiple databases, 42 interventions identified from 47 publications met the inclusion criteria for this review. Most individual-level interventions were delivered via text messages and/or apps and incorporated personalized elements to tailor the intervention content on participants' demographic characteristics or HIV risk behaviors. Interpersonal-level interventions often employed peer mentors or social network strategies to enhance PrEP adoption among MSM of minority race. However, few interventions were implemented at the community-, healthcare/institution- or multiple levels.

CONCLUSIONS

Interventions that incorporate multiple socioecological levels hold promise to facilitate PrEP adoption and adherence among MSM in the US given their acceptability, feasibility, efficacy and effectiveness. Future PrEP interventions that simultaneously address PrEP-related barriers/facilitators across multiple socioecological levels should be enhanced with a focus to tackle contextual and structural barriers (e.g., social determinants of health, stigma or medical mistrust) at the community- and healthcare/institution-level to effectively promote PrEP use for MSM of color.

Casting a Wide Net: HIV Drug Resistance Monitoring in Pre-Exposure Prophylaxis Seroconverters in the Global Evaluation of Microbicide Sensitivity Project

Global Evaluation of Microbicide Sensitivity projects in 4 countries demonstrated the feasibility of establishing an HIV drug resistance monitoring program for pre-exposure prophylaxis (PrEP). These projects will provide valuable information on seroconversions in the context of PrEP use and will serve to inform Ministries of Health and policy makers on the need for long-term surveillance approaches.

Background:

Evidence of HIV drug resistance (HIVDR) in individuals using oral pre-exposure prophylaxis (PrEP) who acquire HIV is limited to clinical trials and case studies. More data are needed to understand the risk of HIVDR with oral PrEP during PrEP rollout. Mechanisms to collect these data vary, and are dependent on cost, scale of PrEP distribution, and in-country infrastructure for the identification, collection, and testing of samples from PrEP seroconverters.

Methods:

The Global Evaluation of Microbicide Sensitivity (GEMS) project, in collaboration with country stakeholders, initiated HIVDR monitoring among new HIV seroconverters with prior PrEP use in Eswatini, Kenya, South Africa, and Zimbabwe. Standalone protocols were developed to assess HIVDR among a national sample of PrEP users. In addition, HIVDR testing was incorporated into existing demonstration projects for key populations.

Lessons learned:

Countries are supportive of conducting a time-limited evaluation of HIVDR during the early stages of PrEP rollout. As PrEP rollout expands, the need for long-term HIVDR monitoring with PrEP will need to be balanced with maintaining national HIV drug resistance surveillance for pretreatment and acquired drug resistance. Laboratory capacity is a common obstacle to setting up a monitoring system.

Conclusions:

Establishing HIV resistance monitoring within PrEP programs is feasible. Approaches to drug resistance monitoring may evolve as the PrEP programs mature and expand. The methods and implementation support offered by GEMS assisted countries in developing methods to monitor for drug resistance that best fit their PrEP program needs and resources.

HIV-1-infection in a man who has sex with men despite self-reported excellent adherence to pre-exposure prophylaxis, the Netherlands, August 2021: be alert to emtricitabine/tenofovir-resistant strain transmission

In August 2021, a man who has sex with men was diagnosed with HIV-1 infection despite using event-driven pre-exposure prophylaxis for over 2 years with self-reported excellent adherence. Sequencing identified resistance-associated mutations (RAM) M184V and K65R, conferring resistance to emtricitabine and tenofovir, and RAM V108I and E138A. Background RAM prevalence was two of 164 (1.2%) new HIV diagnoses in Amsterdam (2017–19). We reiterate the need for frequent HIV testing among PrEP users and additional testing in case of symptoms.

Drug Resistance Mutations in a Population Before Antiretroviral Therapy Initiation in Northern South Africa

South Africa introduced the "diagnose and treat" universal HIV treatment program in September 2016. This program enables all identified HIV-positive patients to immediately start first-line antiretroviral therapy (ART). However, the presence of drug-resistant (DR) viruses in the drug-naive population complicates the choice of ART. We used next-generation sequencing (NGS) to determine the prevalence and diversity of HIV DR mutations in patients entering HIV treatment programs in northern South Africa. RNA was isolated from plasma of drug-naive HIV-1-infected patients. Using reverse transcriptase polymerase chain reaction, the HIV-1-pol gene comprising the complete protease (PR) and the first 900 bp of reverse transcriptase (RT) was amplified and sequenced on an Illumina MiniSeq platform. Consensus sequences were derived at >20% threshold and at >5% threshold using Geneious PRIME^® software version 2020.1.2. HIV-1 surveillance drug resistance mutations (SDRM) were inferred using Calibrated Population Resistance tool in HIV Drug Resistance Database. Viral subtypes were determined using REGA and RIP genotyping tools. The HIV PR/RT region was successfully sequenced from 241 patients. From these, 23 (9.5%) had at least one SDRM detected at >20% threshold, with a prevalence of 9.5% (n = 18), 3% (n = 7), and 0.4% (n = 1) for non-nucleoside reverse transcriptase inhibitors (NNRTI), nucleoside reverse transcriptase inhibitors (NRTI), and protease inhibitors (PI), respectively. The number of patients with SDRM increased to 31 (12.9%) when minority variants were accounted for at >5% threshold. The most frequent SDRMs based on drug class were; K103N (7.9%-NNRTI), K65R (2.5%-NRTI), and D30N (0.8%-PI). Four cases of dual NRTI/NNRTI mutations were identified. All consensus sequences were subtype C, except three, which were C/A1, C/F1, and C/G recombinants. NGS analysis confirms that individuals entering HIV treatment programs in northern South Africa, habor moderate levels of SDRM, including cases of dual-class drug resistance. Further SDRM studies may be required to better understand resistance in the drug-naive population in the era of "diagnose and treat" in Limpopo Province, South Africa.

Multidrug Resistance (MDR): A Widespread Phenomenon in Pharmacological Therapies

Multidrug resistance is a leading concern in public health. It describes a complex phenotype whose predominant feature is resistance to a wide range of structurally unrelated cytotoxic compounds, many of which are anticancer agents. Multidrug resistance may be also related to antimicrobial drugs, and is known to be one of the most serious global public health threats of this century. Indeed, this phenomenon has increased both mortality and morbidity as a consequence of treatment failures and its incidence in healthcare costs. The large amounts of antibiotics used in human therapies, as well as for farm animals and even for fishes in aquaculture, resulted in the selection of pathogenic bacteria resistant to multiple drugs. It is not negligible that the ongoing COVID-19 pandemic may further contribute to antimicrobial resistance. In this paper, multidrug resistance and antimicrobial resistance are underlined, focusing on the therapeutic options to overcome these obstacles in drug treatments. Lastly, some recent studies on nanodrug delivery systems have been reviewed since they may represent a significant approach for overcoming resistance.

HIV pre-exposure prophylaxis and sexually transmitted infections: intersection and opportunity

Pre-exposure prophylaxis (PrEP) has revolutionized HIV prevention, but PrEP does not protect against other sexually transmitted infections (STIs). Rates of STIs are rising worldwide, with notably high incidences among PrEP-using men who have sex with men in high-income countries; in low-income and middle-income countries, data are sparse, but results from a limited number of studies among African women initiating and taking PrEP have shown high STI prevalence and incidence. Efforts aimed at markedly reducing HIV in populations worldwide include a major focus on increasing PrEP use, along with improving HIV testing and treatment in order to eliminate HIV transmission. Together, these efforts could augment continued expansion of the global STI epidemic, but they could alternatively create an opportunity to improve STI control, including the development of comprehensive sexual health programmes and research to develop new STI prevention strategies. The introduction of PrEP globally has been characterized by challenges and many successes, and its role as part of a range of robust strategies to reduce HIV infections is clear. Looking ahead, understanding rising rates of curable STIs and their relationship to HIV prevention, and considering the future directions for synergies in PrEP and STI prevention will be integral to improving sexual health.

Preferences regarding emerging HIV prevention technologies among Toronto men who have sex with men: a discrete choice experiment

New forms of HIV pre-exposure prophylaxis (PrEP) include long-acting injectables and topical microbicides, each with unique attributes that may appeal to distinct users. We used a discrete choice experiment to characterize preferences for new PrEP formulations among Toronto men who have sex with men. MSM undergoing anonymous HIV testing completed a discrete choice experiment with 12 choice sets by selecting their preferred option within each set. Each set included “usual methods to prevent HIV” (excluding PrEP) as one alternative and two hypothetical PrEP alternatives, which differed according formulation/dosing, side effects (none/mild), risk of drug resistance (none/low/moderate), and HIV prevention efficacy (50%, 65%, 80% or 99% risk reduction). We used mixed logistic regression to infer preferences for PrEP attributes and calculate the marginal rate of substitution between efficacy and other PrEP attributes. 306 men with median (interquartile range) age = 29 (25, 36) years participated, and reported 6 (3, 10) partners and 0 (0, 2) condomless receptive anal sex acts in the preceding six months. An on-demand pill was the most preferred formulation, followed by a monthly injection, daily pill, and on-demand rectal gel. Drug resistance was an important determinant of preferences if the risk was moderate, but not if it was low. The minimum efficacy required for an on-demand pill to be preferred over no PrEP was 32.6% (95%CI = 21.2–43.9%); for a daily pill, injections, and rectal gel, minimum efficacy was 57.9% (95%CI = 44.1–71.7%), 40.1% (27.0–53.2%), and 71.3% (60.5–82.1%), respectively. Attitudes towards PrEP formulations vary among men who have sex with men, with on-demand pills and monthly injections having the highest average preference scores. Understanding these preferences may help to predict uptake.

HIV-1 Nucleic Acids Identify Rectal HIV Exposures in Self-Collected Rectal Swabs, Whereas Y-Chromosome Single Tandem Repeat Mixtures Are Not Reliable Biomarkers of Condomless Receptive Anal Intercourse

BACKGROUND

To focus interventions, biomarkers of HIV-1 exposure could help in identifying subpopulations at highest risk of acquisition. We assessed whether Y-chromosome single tandem repeat (YSTR) mixtures obtained from rectal swabs could serve as a biomarker of condomless receptive anal intercourse (CRAI) among men who have sex with men and transgender women and evaluated the feasibility of detecting HIV-1 virions to assess exposures.

METHODS

Twenty-nine sexually active HIV-seronegative men who have sex with men and one transgender woman from New York City answered on-site and mobile app sexual behavior questionnaires. They were randomized to collecting self-administered rectal swabs every morning or after receptive anal intercourse (RAI). YSTR profiles were assessed from blood sample and swabs; HIV-1 exposure was measured by conducting quantitative polymerase chain reaction in swabs.

RESULTS

After 2 months, the daily mobile survey had 135%-201% more instances of anal sex acts and 170%-193% more RAI than on-site surveys. Daily mobile reporting had 11%-35% less CRAI events than those reported on-site (Pdaily = 0.001; Pper-sex = 0.047). The daily swabbing arm reported less RAI (P < 0.001) and CRAI (P < 0.038) and had 2.95 lower odds of detecting YSTR mixtures (P = 0.021) than the per-sex-event arm. Surprisingly, YSTR detection was not significantly modified by report of bowel movements and lubricant, enema, or condom use. No participant became HIV-1 infected, yet HIV-1 total nucleic acids were detected in 6 independent episodes of CRAI in 2 participants taking pre-exposure prophylaxis.

CONCLUSIONS

YSTR mixtures demonstrated 80% specificity but only 30% sensitivity as a biomarker of CRAI in self-collected rectal swabs. However, detection of HIV-1 exposures in self-collected swabs may help in identifying those needing further HIV risk reduction strategies.

Brief Report: Prevalence Trend of Transmitted Drug Resistance in a Prospective Cohort of Thai People With Acute HIV Infection

BACKGROUND

The greater availability of different antiretroviral therapy regimens in developing countries may influence the emergence of transmitted drug resistance (TDR). People with acute HIV infection (AHI) represent the best opportunity for real-time monitoring of TDR. This study assessed the TDR prevalence trends over time in a Thai cohort of predominantly men who have sex with men (MSM) with AHI.

METHODS

At the time of RV254/SEARCH010 study (NCT00796146) enrollment and before starting ART, HIV genotyping was used to identify mutations in the reverse transcriptase and protease genes. Testing for TDR mutations was obtained by a validated in-house method with TRUGENE assay in a subset. Genotype sequences were analyzed using the Stanford University HIV Drug Resistance Database.

RESULTS

Genotyping was performed for 573 participants with AHI. Their median age was 26 years (interquartile range 22-31), 97.4% were men, and 94.1% were MSM. Overall TDR prevalence was 7.0%, declining from 12.5% in 2009-2010 to 4.8% in 2017-2018. A declining resistance prevalence to nonnucleoside reverse transcriptase inhibitor emerged from 9.4% in 2009-2010 to 3.5% in 2017-2018 and to nucleoside reverse transcriptase inhibitor from 6.3% to 2.1%. Protease inhibitor resistance showed a decreased TDR level from 3.1% in 2009-2010 to 1.4% in 2017-2018.

CONCLUSIONS

We report an encouraging declining trend in TDR prevalence in a Thai cohort of mainly MSM from 2009 to 2018; in 2017-2018, we observed a low TDR prevalence according to the World Health Organization definition.

Transmitted Drug Resistance Among HIV-1 Diagnoses in the United States, 2014-2018

BACKGROUND

Transmitted HIV drug resistance can threaten the efficacy of antiretroviral therapy (ART) and preexposure prophylaxis (PrEP). Drug resistance testing is recommended at entry to HIV care in the United States and provides valuable insight for clinical decision-making and population-level monitoring.

METHODS

We assessed transmitted drug resistance-associated mutation (TDRM) prevalence and predicted susceptibility to common HIV drugs among U.S. persons with HIV diagnosed during 2014-2018 who had a drug resistance test performed ≤3 months after HIV diagnosis and reported to the National HIV Surveillance System and who resided in 28 jurisdictions where ≥20% of HIV diagnoses had an eligible sequence during this period.

RESULTS

Of 50,747 persons in the analysis, 9,616 (18.9%) had ≥1 TDRM. TDRM prevalence was 0.8% for integrase strand transfer inhibitors (INSTI), 4.2% for protease inhibitors, 6.9% for nucleoside reverse transcriptase inhibitors, and 12.0% for non-nucleoside reverse transcriptase inhibitors. Most individual mutations had a prevalence <1.0% including M184V (0.9%) and K65R (0.1%); K103N was most prevalent (8.6%). TDRM prevalence did not increase or decrease significantly during 2014-2018 overall, for individual drug classes, or for key individual mutations except for M184V (12.9% increase per year, 95% CI=5.6-20.6).

CONCLUSIONS

TDRM prevalence overall and for individual drug classes remained stable during 2014-2018; transmitted INSTI resistance was uncommon. Continued population-level monitoring of INSTI and NRTI mutations, especially M184V and K65R, is warranted amidst expanding use of second-generation INSTI and PrEP.

Use of Drug-level Testing and Single-genome Sequencing to Unravel a Case of Human Immunodeficiency Virus Seroconversion on Pre-exposure Prophylaxis

Cases of seroconversion on pre-exposure prophylaxis (PrEP) should be carefully investigated, given their public health implications and rarity. We report a case of transmitted drug resistance causing seroconversion on PrEP in spite of high adherence, confirmed with dried blood spot and segmental hair drug-level testing and single-genome sequencing.

Infection with antiretroviral-susceptible HIV in an individual adherent to pre-exposure prophylaxis: strategies for treatment initiation

HIV pre-exposure prophylaxis (PrEP) is effective at preventing sexual acquisition of HIV, and failures in clinical trials are largely attributable to medication nonadherence. We report here a case of infection with a fully susceptible strain of HIV in an individual adherent to PrEP as demonstrated by pharmacy records and intracellular tenofovir diphosphate levels. At diagnosis, the viral load was 90 copies/mL precluding initial genotype testing due to low copy number. While PrEP failure is rare, this case underscores the importance of regular HIV testing for patient on PrEP and prompts discussion regarding the approach to treatment following failure where an initial genotype is not yet available or not possible due to low viral load. Few other case reports of PrEP failure exist in the literature and approaches to treatment varied widely. We suggest the initial viral copy number may guide next steps and discuss the risks and benefits of stopping PrEP, escalating therapy with integrase inhibitors or boosted protease inhibitors, or switching to non-nucleoside antiretroviral treatment regimens.

HIV incidence after pre-exposure prophylaxis initiation among women and men at elevated HIV risk: A population-based study in rural Kenya and Uganda

BACKGROUND

Oral pre-exposure prophylaxis (PrEP) is highly effective for HIV prevention, but data are limited on HIV incidence among PrEP users in generalized epidemic settings, particularly outside of selected risk groups. We performed a population-based PrEP study in rural Kenya and Uganda and sought to evaluate both changes in HIV incidence and clinical and virologic outcomes following seroconversion on PrEP.

METHODS AND FINDINGS

During population-level HIV testing of individuals ≥15 years in 16 communities in the Sustainable East Africa Research in Community Health (SEARCH) study (NCT01864603), we offered universal access to PrEP with enhanced counseling for persons at elevated HIV risk (based on serodifferent partnership, machine learning-based risk score, or self-identified HIV risk). We offered rapid or same-day PrEP initiation and flexible service delivery with follow-up visits at facilities or community-based sites at 4, 12, and every 12 weeks up to week 144. Among participants with incident HIV infection after PrEP initiation, we offered same-day antiretroviral therapy (ART) initiation and analyzed HIV RNA, tenofovir hair concentrations, drug resistance, and viral suppression (<1,000 c/ml based on available assays) after ART start. Using Poisson regression with cluster-robust standard errors, we compared HIV incidence among PrEP initiators to incidence among propensity score-matched recent historical controls (from the year before PrEP availability) in 8 of the 16 communities, adjusted for risk group. Among 74,541 individuals who tested negative for HIV, 15,632/74,541 (21%) were assessed to be at elevated HIV risk; 5,447/15,632 (35%) initiated PrEP (49% female; 29% 15-24 years; 19% in serodifferent partnerships), of whom 79% engaged in ≥1 follow-up visit and 61% self-reported PrEP adherence at ≥1 visit. Over 7,150 person-years of follow-up, HIV incidence was 0.35 per 100 person-years (95% confidence interval [CI] 0.22-0.49) among PrEP initiators. Among matched controls, HIV incidence was 0.92 per 100 person-years (95% CI 0.49-1.41), corresponding to 74% lower incidence among PrEP initiators compared to matched controls (adjusted incidence rate ratio [aIRR] 0.26, 95% CI 0.09-0.75; p = 0.013). Among women, HIV incidence was 76% lower among PrEP initiators versus matched controls (aIRR 0.24, 95% CI 0.07-0.79; p = 0.019); among men, HIV incidence was 40% lower, but not significantly so (aIRR 0.60, 95% CI 0.12-3.05; p = 0.54). Of 25 participants with incident HIV infection (68% women), 7/25 (28%) reported taking PrEP ≤30 days before HIV diagnosis, and 24/25 (96%) started ART. Of those with repeat HIV RNA after ART start, 18/19 (95%) had <1,000 c/ml. One participant with viral non-suppression was found to have transmitted viral resistance, as well as emtricitabine resistance possibly related to PrEP use. Limitations include the lack of contemporaneous controls to assess HIV incidence without PrEP and that plasma samples were not archived to assess for baseline acute infection.

CONCLUSIONS

Population-level offer of PrEP with rapid start and flexible service delivery was associated with 74% lower HIV incidence among PrEP initiators compared to matched recent controls prior to PrEP availability. HIV infections were significantly lower among women who started PrEP. Universal HIV testing with linkage to treatment and prevention, including PrEP, is a promising approach to accelerate reductions in new infections in generalized epidemic settings.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01864603.

Primary HIV-1 infection in users of pre-exposure prophylaxis

Pre-exposure prophylaxis (PrEP) has proven to be a highly effective and safe way to prevent HIV infection. Seroconversion and primary HIV infection are exceptional if adherence to PrEP is good. However, primary HIV infection while using PrEP can occur, albeit rarely, and HIV drug resistance might develop. Furthermore, the scope of PrEP is expected to expand, and clinicians might face potential seroconversions and primary HIV infection in patients starting or taking PrEP. The characteristics of primary HIV infection in users of PrEP are poorly described. PrEP users present a lower viral load peak during primary HIV infection and, frequently, fewer symptoms than individuals not exposed to PrEP. Additionally, PrEP prolongs the stages of seroconversion, thus potentially complicating diagnosis of primary HIV infection. Drug resistance is rare, occurring mostly when PrEP is initiated in undiagnosed patients who are at an extremely early stage of infection, in whom detection of HIV-RNA was not used to rule out HIV infection. Therefore, careful exclusion of primary HIV infection before starting PrEP is crucial. In patients presenting with primary HIV infection while on PrEP, a drug with a high genetic barrier (or even two) should be added to tenofovir disoproxil fumarate-emtricitabine until test results for resistance are available.

Approaches to Objectively Measure Antiretroviral Medication Adherence and Drive Adherence Interventions

PURPOSE OF REVIEW

Traditional methods to assess antiretroviral adherence, such as self-report, pill counts, and pharmacy refill data, may be inaccurate in determining actual pill-taking to both antiretroviral therapy (ART) or pre-exposure prophylaxis (PrEP). HIV viral loads serve as surrogates of adherence on ART, but loss of virologic control may occur well after decreases in adherence and viral loads are not relevant to PrEP.

RECENT FINDINGS

Pharmacologic measures of adherence, electronic adherence monitors, and ingestible electronic pills all serve as more objective metrics of adherence, surpassing self-report in predicting outcomes. Pharmacologic metrics can identify either recent adherence or cumulative adherence. Recent dosing measures include antiretroviral levels in plasma or urine, as well as emtricitabine-triphosphate in dried blood spots (DBS) for those on tenofovir-emtricitabine-based therapy. A urine tenofovir test has recently been developed into a point-of-care test for bedside adherence monitoring. Cumulative adherence metrics assess adherence over weeks to months and include measurement of tenofovir-diphosphate in peripheral blood mononuclear cells or DBS, as well as ART levels in hair. Electronic adherence monitors and ingestible electronic pills can track pill bottle openings or medication ingestion, respectively. New and objective approaches in adherence monitoring can be used to detect nonadherence prior to loss of prevention efficacy or virologic control with PrEP or ART, respectively.

A review of reported cases of HIV pre-exposure prophylaxis failure with resultant breakthrough HIV infections

OBJECTIVES

Early randomized controlled trials (RCTs) have confirmed high efficacy of pre-exposure prophylaxis (PrEP) for preventing HIV infection in men who have sex with men (MSM) with high HIV exposure risk. Nevertheless, some PrEP failure cases have been reported despite adequate drug adherence. This review aims to summarize the common features of PrEP failure cases and discuss the implications of upscaling PrEP programmes.

METHODS

A search based on articles and clinical trials was conducted through Medline and OVID, with keywords for accessing publications reporting 'true' PrEP failure in the presence of documented adherence to daily regimen of co-formulated tenofovir disoproxil fumarate/emtricitabone.

RESULTS

Ten cases of 'true' PrEP failure were identified, all of which were preceded by continued practice of condomless anal sex, despite documented adherence. Dried blood spot and/or hair analyses provided supporting evidence of adherence in eight cases. There was strong association of PrEP failure with recurrent or multiple sexually transmitted diseases and infection with resistant HIV viruses. Seroconversion was usually atypical or delayed because of significantly suppressed viral load, making diagnosis a clinical challenge.

DISCUSSION

Although it is uncommon, 'true' PrEP failure can occur in a real-world situation, contrary to the outcome of early RCTs. Failure to identify HIV infection while on PrEP can potentially lead to the emergence of drug-resistant virus. To achieve effective HIV prevention, PrEP programmes should emphasize safer sexual practice in addition to drug adherence. Early identification of PrEP failure is crucial, which requires the development of highly sensitive assays and their clinical application.

Implementing a Status-Neutral Approach to HIV in the Asia-Pacific

PURPOSE OF REVIEW

Globally, "undetectable equals untransmittable (U=U)" and "pre-exposure prophylaxis (PrEP)" have become crucial elements in HIV treatment and prevention programs. We reviewed the implementation of U=U and PrEP among countries in the Asia-Pacific region.

RECENT FINDINGS

U=U and PrEP uptakes were limited and slow in the Asia-Pacific. Inadequate knowledge among health care practitioners and pervasive stigma towards individuals living with HIV and their sexual lives are key barriers for the integration of U=U into clinical practice. Paternalistic and hierarchical health care systems are major obstacles in PrEP implementation and scale-up. Countries with the most advanced PrEP implementation all use community-based, nurse-led, and key population-led service delivery models. To advance U=U and PrEP in the Asia-Pacific, strategies targeting changes to practice norm through wide-scale stakeholders' training and education, making use of online health care professional influencers, and utilizing financial mechanism should be further explored through implementation research.

Effect of HIV pre-exposure prophylaxis (PrEP) on detection of early infection and its impact on the appropriate post-PrEP deferral period

INTRODUCTION

HIV antivirals for pre-exposure prophylaxis (PrEP) are known to affect detection of early HIV infection through suppression of viral load and delayed seroconversion. To cover potential delay in HIV detection associated with PrEP use by blood donors in the context of international reductions in sexual activity-based deferral periods, we analysed the available data to determine the appropriate minimum post-PrEP deferral period for blood donation.

MATERIALS AND METHODS

Published cases of incident HIV infection when PrEP use was objectively demonstrable were identified, consisting principally of seroconverters from the Partners PrEP study (a clinical trial of PrEP efficacy). Data were reviewed to determine the impact of PrEP on the detection of HIV RNA, p24 Ag and seroconversion delay.

RESULTS

Nucleic acid testing (NAT) detected early HIV infection in the presence of PrEP prior to or in concordance with serological testing in approximately 90% of cases. Undetectable HIV RNA would rebound to detectable levels within two months of PrEP cessation. PrEP delayed p24 antigen detection and antibody seroconversion by about 7 days.

CONCLUSION

Even when daily PrEP is continued, it is likely that the majority of early HIV infections are detectable by individual donation (ID)-NAT, with p24 Ag or antibody seroconversion occurring conservatively within four weeks of exposure. HIV RNA levels also rebound rapidly in the absence of PrEP. In Australia, a three-month deferral period for blood donation after the last dose of PrEP provides an appropriate safety margin to mitigate the residual risk of transfusion-transmitted HIV.

Tail-phase safety, tolerability, and pharmacokinetics of long-acting injectable cabotegravir in HIV-uninfected adults: a secondary analysis of the HPTN 077 trial

BACKGROUND

Long-acting injectable cabotegravir is a novel integrase inhibitor currently in advanced clinical development for HIV prevention and treatment. We aimed to assess the terminal phase pharmacokinetics and safety of long-acting injectable cabotegravir in participants included in the HPTN 077 trial.

METHODS

HPTN 077 was a multicentre, double-blind, randomised, placebo-controlled phase 2a trial done at eight sites in Brazil, Malawi, South Africa, and the USA. Participants (aged 18-65 years), who were HIV-uninfected and at low-risk for HIV, were randomly assigned (3:1) to long-acting injectable cabotegravir (800 mg given three times at 12 week intervals or 600 mg given five times, administered at one 4 week interval, and every 8 weeks thereafter) or placebo. Participants were followed up to 76 weeks after final injection. In a prespecified analysis of secondary and exploratory outcomes, we assessed the safety, measured by the proportion of participants with grade 2 or worse adverse events, and pharmacokinetics, measured by apparent terminal phase half-life (t_1/2app) and estimated time to lower limit of quantification (LLOQ) of long-acting injectable cabotegravir during the injection phase (defined as the time between first injection and 12 weeks or 8 weeks after the last injection in cohort 1 or cohort 2 respectively) and tail phase (defined as the time between final injection and 52-76 weeks post-final injection). Safety was analysed in all participants who received at least one injection. Pharmacokinetic analyses included all participants who had received at least one injection and had at least three cabotegravir measurements higher than the LLOQ after the final injection. Pharmacokinetic outcomes were estimated using non-compartmental methods. The trial is completed, and was registered with ClinicalTrials.gov, NCT02178800.

FINDINGS

Between Feb 9, 2015, and May 27, 2016, 177 participants (134 participants in the cabotegravir group [74 participants in cohort 1; 60 participants in cohort 2] and 43 participants in the placebo group [25 participants in cohort 1; 18 participants in cohort 2) were enrolled and received at least one injection and thus were included in the safety analysis. The incidence of grade 2 or worse adverse events was significantly lower during the tail phase than the injection phase (p<0·0001). At 52-60 weeks after final injection, nine (23%) of 40 male participants had detectable cabotegravir concentrations and at week 76, four (13%) of 30 male participants had detectable cabotegravir concentrations compared with 52 (63%) of 82 female participants and 27 (42%) of 64 female participants at the same timepoints. The median time from the last injection to the time when cabotegravir concentration decreased below the LLOQ was 43·7 weeks (IQR 31·1-66·6; range 20·4-152·5) for male participants and 67·3 weeks (29·1-89·6; 17·7-225·5) for female participants (p=0·0003). t_1/2app was longer for female participants than male participants (geometric mean fold-change 1·33, 95% CI 1·06-1·68; p=0·014), and longer for participants with a high body-mass index (BMI) than those with a low BMI (1·31, 1·06-1·63; p=0·015).

INTERPRETATION

The clinical significance of the long pharmacokinetic tail of cabotegravir observed in female participants compared with male participants, and those with higher BMI compared with a lower BMI, need to be addressed in future trials.

FUNDING

National Institute of Allergy and Infectious Diseases.

Challenges of HIV diagnosis and management in the context of pre-exposure prophylaxis (PrEP), post-exposure prophylaxis (PEP), test and start and acute HIV infection: a scoping review

INTRODUCTION

Knowledge of HIV status relies on accurate HIV testing, and is the first step towards access to HIV treatment and prevention programmes. Globally, HIV-status unawareness represents a significant challenge for achieving zero new HIV infections and deaths. In order to enhance knowledge of HIV status, the World Health Organisation (WHO) recommends a testing strategy that includes the use of HIV-specific antibody point-of-care tests (POCT). These POCTs do not detect acute HIV infection, the stage of disease when viral load is highest but HIV antibodies are undetectable. Complicating things further, in the presence of antiretroviral therapy (ART) for pre-exposure prophylaxis (PrEP) or post-exposure prophylaxis (PEP), other currently available testing technologies, such as viral load detection for diagnosis of acute HIV infection, may yield false-negative results. In this scoping review, we evaluate the evidence and discuss alternative HIV testing algorithms that may mitigate diagnostic dilemmas in the setting of increased utilization of ART for immediate treatment and prevention of HIV infection.

DISCUSSION

Missed acute HIV infection prevents people living with HIV (PLHIV) from accessing early treatment, increases likelihood of onward transmission, and allows for inappropriate initiation or continuation of PrEP, which may result in HIV drug resistance. While immediate ART is recommended for all PLHIV, studies have shown that starting ART in the setting of acute HIV infection may result in a delayed or complete absence of development of HIV-specific antibodies, posing a diagnostic challenge that is particularly pertinent to resource-limited, high HIV burden settings where HIV-antibody POCTs are standard of care. Similarly, ART used as PrEP or PEP may supress HIV RNA viral load, complicating current HIV testing algorithms in resource-wealthy settings where viral detection is included. As rollout of PrEP continues, HIV testing algorithms may need to be modified.

CONCLUSIONS

With increasing use of PrEP and ART in acute infection we anticipate diagnostic challenges using currently available HIV testing strategies. Research and surveillance are needed to determine the most appropriate assays and optimal testing algorithms that are accurate, affordable and sustainable.

Drug Resistance During HIV Pre-Exposure Prophylaxis

Clinical studies have demonstrated that use of tenofovir disoproxil fumarate with or without emtricitabine as antiretroviral pre-exposure prophylaxis (PrEP) can decrease the risk of human immunodeficiency virus (HIV) acquisition when medication adherence is high. However, the potential for PrEP to promote antiretroviral resistance remains an important public health consideration. We performed a search of the medical literature to identify studies that address HIV drug resistance during PrEP use. In this review, we summarize findings about emergent drug resistance during clinical trials of PrEP, case reports of seroconversions in patients adherent to PrEP, and animal studies of PrEP effectiveness against drug-resistant viral strains. We also discuss the potential utility of novel PrEP formulations for protection against drug-resistant HIV, the impact of drug resistance on HIV treatment options, and mathematical models that estimate the potential contribution of PrEP to population-level drug resistance. Evidence suggests that selection for HIV drug resistance with PrEP use is infrequent and most likely to occur when PrEP is used during undiagnosed acute HIV infection. Breakthrough infections during PrEP use with high adherence are possible, but appear to be rare. The prevalence of drug-resistant HIV strains needs to be monitored as PrEP is scaled up. However, the benefit of a decreased HIV incidence with wider PrEP use is likely to outweigh the risk of harms from possible increases in the prevalence of HIV drug resistance.

Update on HIV Preexposure Prophylaxis: Effectiveness, Drug Resistance, and Risk Compensation

PURPOSE OF REVIEW

In 2019, the US government launched an initiative to decrease new HIV infections by 90% over the next decade. Studies have demonstrated the efficacy of HIV preexposure prophylaxis (PrEP) for high-risk populations, and the United States Preventative Services Task Force has issued a grade A recommendation for PrEP, indicating substantial net benefit. However, questions have been raised about the effectiveness of PrEP in clinical settings and whether PrEP use might promote antiretroviral drug resistance and increased sexual risk behaviors, which could increase transmission of bacterial sexually transmitted infections. In this narrative review, we summarize recent evidence of the effectiveness of PrEP when provided in clinical and community settings, the emergence of antiretroviral drug resistance during PrEP use, and associations between PrEP use and increased sexual risk behaviors. We also review novel PrEP modalities that are being developed to optimize PrEP acceptability, adherence, and effectiveness.

RECENT FINDINGS

Studies suggest that PrEP is effective when provided in clinical settings. However, PrEP uptake and impact have been limited in the USA thus far, and major disparities in access to PrEP exist. In addition, there is evidence that drug resistance can occur with PrEP use, particularly with inadvertent PrEP use during undiagnosed acute HIV infection. Risk compensation can also occur with PrEP use and has been associated with increased sexually transmitted infections. Promising new modalities for PrEP could expand options. PrEP has strong potential to decrease HIV incidence. However, disparities in access must be addressed to ensure equity and impact for PrEP. While drug resistance and risk compensation can occur with PrEP use, these are not valid reasons to withhold PrEP from patients given its substantial protective benefits.

Acquisition of tenofovir-susceptible, emtricitabine-resistant HIV despite high adherence to daily pre-exposure prophylaxis: a case report

BACKGROUND

Pre-exposure prophylaxis (PrEP) with emtricitabine and tenofovir disoproxil fumarate is highly protective against HIV infection. We report a case of tenofovir-susceptible, emtricitabine-resistant HIV acquisition despite high adherence to daily PrEP.

METHODS

Adherence to PrEP was assessed by measuring concentrations of emtricitabine and tenofovir disoproxil fumarate or their metabolites in plasma, dried blood spots, and hair. After seroconversion, genotypic and phenotypic resistance of the acquired virus was determined by standard clinical tests and by single-genome sequencing of proviral genomes. HIV partner services identified the likely transmission partner.

FINDINGS

A 21-year-old Latino man tested positive for HIV infection 13 months after PrEP initiation. He had a negative HIV antibody test, but detectable HIV RNA with 559 copies per mL. He reported good adherence to daily PrEP. He was linked to care and immediately started antiretroviral therapy, at which point his RNA was 1544 copies per mL and his HIV antibody test was positive. The HIV genotype revealed Met184Val, Leu74Val, Leu100Ile, and Lys103Asn mutations in reverse transcriptase, and the phenotype showed susceptibility to tenofovir disoproxil fumarate and resistance to emtricitabine. Segmental hair analysis of tenofovir disoproxil fumarate concentrations measured in 1 cm segments of hair from the scalp indicated consistently high adherence to PrEP in each of the 6 months before HIV diagnosis (0·0672-0·0889 ng/mg). Concentrations of tenofovir diphosphate (1012 fmol per punch) and emtricitabine triphosphate (0·266 fmol per punch) in a dried blood spot indicated high adherence over the preceding 6 weeks. Concentrations of emtricitabine (870·5 ng/mL) and tenofovir disoproxil fumarate (188·2 ng/mL) measured in plasma 3 months before HIV seroconversion confirmed adherence in the days preceding that visit. The likely transmission partner was not engaged in HIV primary care and had a similar viral genotype.

INTERPRETATION

Acquisition of HIV virus that is susceptible to tenofovir disoproxil fumarate, but resistant to emtricitabine can occur despite high adherence to PrEP. Quarterly screening for HIV and sexually transmitted diseases facilitates early diagnosis in people on PrEP; when combined with prompt linkage to care and partner services this can prevent onward transmission of HIV.

FUNDING

US National Institutes of Health.