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Cabotegravir plus Rilpivirine for Persons with HIV and Adherence Challenges. BACKGROUND: Randomized trials of long-acting injectable antiretroviral therapy (ART) in persons with human immunodeficiency virus (HIV) who face challenges with adherence to oral medication are lacking. METHODS: We conducted an open-label, randomized trial involving persons with HIV who had inadequate adherence to ART (a persistent HIV-1 RNA level of >200 copies per milliliter or loss to follow-up). Participants received up to 24 weeks of adherence support, conditional economic incentives, and standard care with oral ART (step 1). Participants who had an HIV-1 RNA level of 200 copies per milliliter or lower in step 1 were randomly assigned in a 1:1 ratio to either continue standard care or switch to monthly injections of long-acting cabotegravir plus rilpivirine with or without oral lead-in therapy (step 2). The primary outcome was regimen failure, defined as confirmed virologic failure (two consecutive HIV-1 RNA measurements of >200 copies per milliliter) or treatment discontinuation during step 2. RESULTS: In step 1 of the trial, we enrolled 453 participants; the median age was 40 years, 63% were Black, and 29% had been assigned female sex at birth. In step 2, a total of 306 participants underwent randomization; 152 were assigned to receive cabotegravir-rilpivirine and 154 to receive standard care. Step 2 randomization was stopped early on the basis of the superiority of cabotegravir-rilpivirine to standard care in secondary outcomes at a prespecified analysis performed after a median follow-up of 48 weeks. The cumulative incidence of regimen failure by week 48 was 22.8% in the cabotegravir-rilpivirine group and 41.2% in the standard-care group (difference, -18.4 percentage points; 98.4% confidence interval [CI], -32.4 to -4.3; P = 0.002). The cumulative incidence of an adverse event was 43.5% in the cabotegravir-rilpivirine group and 42.4% in the standard-care group (difference, 1.1 percentage points; 95% CI, -12.7 to 15.0). Resistance-associated mutations developed in 2 participants with confirmed virologic failure in each group. CONCLUSIONS: Monthly injections of long-acting cabotegravir-rilpivirine were superior to standard oral ART in reducing the risk of regimen failure among persons with HIV who had adherence challenges. (Funded by the National Institute of Allergy and Infectious Diseases; LATITUDE ClinicalTrials.gov number, NCT03635788.).

Eligible participants were ART-experienced, PWH ≥18 years of age without Hepatitis B co-infection, and no clinically relevant RPV or integrase strand-transfer inhibitor (INSTI) resistance-associated mutations with non-adherence, defined as poor virologic response while being prescribed ART, and/or loss to clinical follow-up with ART non-adherence, each for ≥6 consecutive months, and within 18 months prior to study entry. Full eligibility criteria, trial design and protocol are provided in the Supplementary Appendix at nejm.org. The A5359 protocol was approved by both central and local institutional review boards. All participants provided written informed consent. The National Institute of Allergy and Infectious Diseases Division of AIDS provided regulatory sponsorship and held responsibility for clinical monitoring. ViiV Healthcare and Johnson & Johnson donated ART and contributed to trial design. All the authors vouch for the accuracy and completeness of the data and the fidelity to the protocol.

te of Allergy and Infectious Diseases Division of AIDS provided regulatory sponsorship and held responsibility for clinical monitoring. ViiV Healthcare and Johnson & Johnson donated ART and contributed to trial design. All the authors vouch for the accuracy and completeness of the data and the fidelity to the protocol. The trial was designed with two steps for the primary outcome followed by either an extension phase (Step 3) for participants continuing LAI or an observation phase (Step 4) for those discontinuing LAI (Figure 1A); this report focuses on the primary outcome. In Step 1, participants initiated SOC oral ART consisting of at least ≥3 drugs with ≥2 predicted to be fully active, including a boosted protease inhibitor and/or an INSTI for up to 24 weeks. Participants in Step 1 received adherence support and were eligible for conditional economic incentives at each Step 1 visit (maximum $675 total) for achieving benchmarks in visit completion and/or decreased viral load (Supplementary Appendix).12,13 Participants achieving virologic suppression during Step 1 were randomized 1:1 at Step 2 enrollment to continue SOC or switch to LAI for 52 weeks. Those randomized to LAI received an optional oral lead-in with daily CAB 30 mg and RPV 25 mg for approximately 4 weeks followed by loading injections of CAB 600 mg (3mL)/RPV 900 mg (3mL). Subsequent injections of CAB 400 mg (2mL)/RPV 600 mg (2 mL) were administered within 24 to 32 days after the previous injection for the second and third injections, and within 21 to 35 days thereafter. Step 2 participants received continued adherence support without conditional economic incentives. Randomization used permuted blocks with balancing by site. Three protocol versions were implemented prior to this primary analysis (Supplementary Appendix). Major changes among versions included: a) modification in the viral load threshold to advance into Step 2 from <50 copies/mL in version 1 to <200 copies/mL in version 2; b) shortening of the required time in Step 1 prior to randomization in Step 2 from 20 weeks in version 1 to 12 weeks in version 2 and 4 weeks in version 3; c) allowing enrollment of participants who were virally suppressed at screening but had an HIV VL >200 copies/mL within 12 months prior to study entry in version 3, and; d) optionality of optional oral lead-in in versions 2 and 3.

n in Step 2 from 20 weeks in version 1 to 12 weeks in version 2 and 4 weeks in version 3; c) allowing enrollment of participants who were virally suppressed at screening but had an HIV VL >200 copies/mL within 12 months prior to study entry in version 3, and; d) optionality of optional oral lead-in in versions 2 and 3. After enrollment, participants were asked to return every 4 weeks to assess conditional economic incentives eligibility in Step 1 or receive LAI injections in Step 2. Participants randomized to continuation of SOC in Step 2 had less frequent visits (every 8 weeks starting at week 12 and every 12 weeks at week 24) to more closely mimic US standard of care for individuals with adherence challenges. The primary outcome was regimen failure in Step 2, defined as the earliest occurrence of either confirmed virologic failure (two consecutive HIV-1 RNA >200 copies/mL post randomization) or permanent discontinuation of study treatment (including death and never initiated treatment). Secondary outcomes reported here included virologic failure, treatment-related failure (i.e., earliest occurrence of virologic failure or premature treatment discontinuation due to treatment-related AE), genotypic resistance with virologic failure, adverse events (AE), and plasma pharmacokinetics of CAB and RPV in participants with confirmed virologic failure. Additional participant reported outcomes are available in the Supplementary Appendix.

ailure or premature treatment discontinuation due to treatment-related AE), genotypic resistance with virologic failure, adverse events (AE), and plasma pharmacokinetics of CAB and RPV in participants with confirmed virologic failure. Additional participant reported outcomes are available in the Supplementary Appendix. A sample size of 320 participants in Step 2 was estimated to provide approximately 80% power to detect a 16-percentage point difference in the cumulative probability of regimen failure between the LAI and SOC arms, using a two-sided 5% type I error rate. The primary analysis was based on the intention-to-treat principle. Comparison of treatment arms was made using the difference in the Kaplan-Meier estimate for the week 48 cumulative probability of regimen failure. Analysis of secondary efficacy outcomes of virologic failure, treatment-related failure, and premature treatment discontinuation followed the same analysis approach. For analysis of virologic failure, participants who prematurely discontinued the study follow-up or died were censored. Treatment effects for the primary and secondary efficacy outcomes were evaluated in pre-specified subgroups. Details of other secondary outcome measures, supportive analyses and statistical analysis methods are available in the Supplementary Appendix.

prematurely discontinued the study follow-up or died were censored. Treatment effects for the primary and secondary efficacy outcomes were evaluated in pre-specified subgroups. Details of other secondary outcome measures, supportive analyses and statistical analysis methods are available in the Supplementary Appendix. Interim efficacy analyses were conducted using the Lan-DeMets spending function analog of the O’Brien-Fleming boundaries.14 At the second planned efficacy review on February 12, 2024 which included trial data through January 3, 2024, the Data and Safety Monitoring Board recommended halting randomization to Step 2 based on efficacy of secondary outcomes of virologic failure and treatment-related failure (Supplementary Appendix). The analyses in this manuscript include data collected up to the date of the efficacy review on February 12, 2024 with 76.6% information fraction, leading to a Type I error of 0.0161. Two-sided 98.4% CIs were provided for the primary and secondary efficacy outcomes. Other outcomes were summarized with point estimates and two-sided 95% CIs. The widths of the confidence intervals were not adjusted for multiplicity and should not be used to infer definitive treatment effects for secondary outcomes and subgroup analyses. All analyses were performed with the use of SAS software (version 9.4M7 for Linux).

The trial was designed with two steps for the primary outcome followed by either an extension phase (Step 3) for participants continuing LAI or an observation phase (Step 4) for those discontinuing LAI (Figure 1A); this report focuses on the primary outcome. In Step 1, participants initiated SOC oral ART consisting of at least ≥3 drugs with ≥2 predicted to be fully active, including a boosted protease inhibitor and/or an INSTI for up to 24 weeks. Participants in Step 1 received adherence support and were eligible for conditional economic incentives at each Step 1 visit (maximum $675 total) for achieving benchmarks in visit completion and/or decreased viral load (Supplementary Appendix).12,13 Participants achieving virologic suppression during Step 1 were randomized 1:1 at Step 2 enrollment to continue SOC or switch to LAI for 52 weeks. Those randomized to LAI received an optional oral lead-in with daily CAB 30 mg and RPV 25 mg for approximately 4 weeks followed by loading injections of CAB 600 mg (3mL)/RPV 900 mg (3mL). Subsequent injections of CAB 400 mg (2mL)/RPV 600 mg (2 mL) were administered within 24 to 32 days after the previous injection for the second and third injections, and within 21 to 35 days thereafter. Step 2 participants received continued adherence support without conditional economic incentives. Randomization used permuted blocks with balancing by site. Three protocol versions were implemented prior to this primary analysis (Supplementary Appendix). Major changes among versions included: a) modification in the viral load threshold to advance into Step 2 from <50 copies/mL in version 1 to <200 copies/mL in version 2; b) shortening of the required time in Step 1 prior to randomization in Step 2 from 20 weeks in version 1 to 12 weeks in version 2 and 4 weeks in version 3; c) allowing enrollment of participants who were virally suppressed at screening but had an HIV VL >200 copies/mL within 12 months prior to study entry in version 3, and; d) optionality of optional oral lead-in in versions 2 and 3.

After enrollment, participants were asked to return every 4 weeks to assess conditional economic incentives eligibility in Step 1 or receive LAI injections in Step 2. Participants randomized to continuation of SOC in Step 2 had less frequent visits (every 8 weeks starting at week 12 and every 12 weeks at week 24) to more closely mimic US standard of care for individuals with adherence challenges. The primary outcome was regimen failure in Step 2, defined as the earliest occurrence of either confirmed virologic failure (two consecutive HIV-1 RNA >200 copies/mL post randomization) or permanent discontinuation of study treatment (including death and never initiated treatment). Secondary outcomes reported here included virologic failure, treatment-related failure (i.e., earliest occurrence of virologic failure or premature treatment discontinuation due to treatment-related AE), genotypic resistance with virologic failure, adverse events (AE), and plasma pharmacokinetics of CAB and RPV in participants with confirmed virologic failure. Additional participant reported outcomes are available in the Supplementary Appendix.

A sample size of 320 participants in Step 2 was estimated to provide approximately 80% power to detect a 16-percentage point difference in the cumulative probability of regimen failure between the LAI and SOC arms, using a two-sided 5% type I error rate. The primary analysis was based on the intention-to-treat principle. Comparison of treatment arms was made using the difference in the Kaplan-Meier estimate for the week 48 cumulative probability of regimen failure. Analysis of secondary efficacy outcomes of virologic failure, treatment-related failure, and premature treatment discontinuation followed the same analysis approach. For analysis of virologic failure, participants who prematurely discontinued the study follow-up or died were censored. Treatment effects for the primary and secondary efficacy outcomes were evaluated in pre-specified subgroups. Details of other secondary outcome measures, supportive analyses and statistical analysis methods are available in the Supplementary Appendix.

Between March 28, 2019 and February 12, 2024, 820 adults were screened at 33 sites across the US and 453 eligible participants enrolled into Step 1 (Figure 1B). Median age for Step 1 participants was 40 (Q1, Q3: 31, 52) years, 29% were female sex at birth, 63% were Black, 17% were Hispanic, and 14% reported either ongoing or prior injection drug use (Table 1). Social determinants of health informing outcomes among PWH15,16 including household income and housing status (Table 1), as well as employment, insurance, and education level (Supplementary Appendix) were assessed. Alcohol use screening and urine drug testing were assessed at baseline and throughout the study (Table 1), in addition to assessments of depression and anxiety (Supplementary Table).

sehold income and housing status (Table 1), as well as employment, insurance, and education level (Supplementary Appendix) were assessed. Alcohol use screening and urine drug testing were assessed at baseline and throughout the study (Table 1), in addition to assessments of depression and anxiety (Supplementary Table). Of the 453 participants enrolled in Step 1, 306 (68%) successfully completed Step 1 and enrolled to Step 2; 54 (12%) did not meet virologic criteria for randomization, 66 (15%) discontinued Step 1 prematurely, and 27 (6%) remained on Step 1 as of February 12, 2024. Of the 306 eligible participants enrolled into Step 2, 152 were randomized to LAI and 154 to SOC (Figure 1C). Three participants (one on LAI and two on SOC) did not initiate randomized treatment. Baseline characteristics were comparable between those who entered Step 2 and those who did not except for CD4+ T-cell count and HIV-1 RNA (Supplementary Appendix). Participants who did not enroll into Step 2 had lower CD4+ T-cells (median 206 vs. 300 cells/mm3) and higher HIV-1 RNA at enrollment (4.23 vs. 2.91 log10 copies/mL). While participants were required to have HIV-1 RNA ≤200 copies/mL at or after Week 4 of Step 1 to be eligible for randomization in Step 2, 24 (16%) LAI and 10 (7%) SOC participants had a HIV-1 RNA >200 copies/mL at the Step 2 randomization visit itself; eight participants (5%) on LAI had HIV-1 RNA >10,000 copies/mL.

). While participants were required to have HIV-1 RNA ≤200 copies/mL at or after Week 4 of Step 1 to be eligible for randomization in Step 2, 24 (16%) LAI and 10 (7%) SOC participants had a HIV-1 RNA >200 copies/mL at the Step 2 randomization visit itself; eight participants (5%) on LAI had HIV-1 RNA >10,000 copies/mL. The median duration of follow-up was 48 weeks (interquartile range: 20, 52). Twenty-five (16%) participants on LAI and 35 (23%) on SOC discontinued randomized treatment prematurely. Twenty participants (13%) on LAI and 24 (16%) on SOC prematurely discontinued study follow-up. Among the 152 eligible participants randomized to LAI, 11 did not initiate injections (6 completed oral lead-in, 2 prematurely discontinued oral lead-in, 2 remained on oral lead-in at data cut-off, and one never initiated oral lead-in). The remaining 141 participants received a total of 1359 injections on Step 2. Ninety-four percent of post-loading dose injections were administered on time. Fifteen (11%) participants had at least one missed injection. Four LAI participants received bridging with oral ART due to anticipated delay in injection administration.

maining 141 participants received a total of 1359 injections on Step 2. Ninety-four percent of post-loading dose injections were administered on time. Fifteen (11%) participants had at least one missed injection. Four LAI participants received bridging with oral ART due to anticipated delay in injection administration. The primary outcome of regimen failure was observed in 29 (19%) participants on LAI and 55 (36%) participants on SOC (Figure 2A). Among LAI regimen failures, 5 had virologic failure as the first event and 24 had permanent treatment discontinuation as the first event. Among SOC failures, 32 had virologic failure as the first event and 23 had permanent treatment discontinuation as the first event. The difference in the Week 48 cumulative probability of regimen failure (LAI - SOC) was −18.4% (98.4% CI: −32.4%, −4.3%, p=0.002) demonstrating superiority of the LAI regimen (Figures 2A/2B). Results of subgroup analyses and supportive analyses are shown in supplemental tables. Six LAI and 34 SOC participants had virologic failure. The treatment difference in the Week 48 cumulative probability of virologic failure was −21.4% (98.4% CI: −33.5%, −9.3%). Nine LAI and 34 SOC participants had treatment-related failure. The difference in the Week 48 cumulative probability of treatment-related failure was −19.2% (98.4% CI: −31.6%, −6.9%). Twenty-six LAI and 37 SOC participants had permanent treatment discontinuation. The treatment difference in the Week 48 cumulative probability of permanent treatment discontinuation was −8.4% (98.4% CI: −21.3%, 4.5%).

the Week 48 cumulative probability of treatment-related failure was −19.2% (98.4% CI: −31.6%, −6.9%). Twenty-six LAI and 37 SOC participants had permanent treatment discontinuation. The treatment difference in the Week 48 cumulative probability of permanent treatment discontinuation was −8.4% (98.4% CI: −21.3%, 4.5%). A total of 60 participants discontinued treatment in Step 2 (25 LAI, 35 SOC). The most common reasons for treatment discontinuation on SOC were loss to follow-up/participant withdrawal (n=20, 57%) and non-compliance with study drug (n=6, 17%), whereas for LAI the reasons were more varied, including: loss to follow-up/participant withdrawal (n=9, 36%), AE (n=4, 16%), death not related to study drug (n=2, 8%), and incarceration (n=2, 8%). Amongst participants who experienced virologic failure and had resistance data available, 2 of 5 (40%) in the LAI arm acquired INSTI resistance-associated mutations (RAMs); 2 of 22 (9%) in the SOC arm acquired RAMs (Figure 3).

36%), AE (n=4, 16%), death not related to study drug (n=2, 8%), and incarceration (n=2, 8%). Amongst participants who experienced virologic failure and had resistance data available, 2 of 5 (40%) in the LAI arm acquired INSTI resistance-associated mutations (RAMs); 2 of 22 (9%) in the SOC arm acquired RAMs (Figure 3). Six participants randomized to LAI experienced virologic failure. One of these initiated oral lead-in but discontinued treatment prior to initiating injections (meeting primary outcome), and was followed in the study with subsequent virologic failure. Of the remaining 5 participants, none had a detectable HIV-1 RNA at LAI initiation, nor any missed injections (Figure 3). Three had delayed injections at least once, though all were delayed by <5 days. While guidelines suggest those with BMI >30 kg/m2 should receive injections with 2” needle lengths,10 the 4 virologic failure participants with BMI >30 kg/m2 received injections with needle lengths of ≤1.6”. All except one virologic failure occurred after week 24 on Step 2. All 4 virologic failure s with successful sub-typing of virus were clade B. All participants with virologic failure subsequently suppressed on oral ART except 1 participant who was lost to follow-up (no RAMs were identified at their virologic failure confirmation visit).

ologic failure occurred after week 24 on Step 2. All 4 virologic failure s with successful sub-typing of virus were clade B. All participants with virologic failure subsequently suppressed on oral ART except 1 participant who was lost to follow-up (no RAMs were identified at their virologic failure confirmation visit). Plasma concentrations of CAB and RPV were all above the lowest quartile at the time of initial and confirmed virologic failure, consistent with previously reported adequate exposure (Figure 3).17,18 However, each participant demonstrated trends in trough concentrations below the lowest quartile for at least one of the agents early after initiating LAI, some of which were also accompanied by a single detectable viral load that re-suppressed by the subsequent visit.

iously reported adequate exposure (Figure 3).17,18 However, each participant demonstrated trends in trough concentrations below the lowest quartile for at least one of the agents early after initiating LAI, some of which were also accompanied by a single detectable viral load that re-suppressed by the subsequent visit. Fifty-two (34%) LAI and 46 (30%) SOC participants had ≥1 AE during Step 2 (Table 2). The difference in the week 48 cumulative probability of AE was 1.1% (95% CI: −12.7%, 15.0%). Twenty-one (14%) LAI and 16 (10%) SOC participants had ≥1 serious AE reported during Step 2 with the difference in the week 48 cumulative probability of 4.8% (95% CI: −5.6%, 15.2%). Four LAI participants discontinued treatment due to AE, two due to low-grade injection site pain or pain/nodule, one due to seizure, and one due to cerebrovascular accident/hemiparesis requiring anti-coagulation that was deemed by the site investigator as not related to study treatment. Only 1 SOC participant discontinued treatment due to AE (ischemic cerebral infarction/encephalopathy). Two deaths (both on the LAI arm, 1 due to fentanyl overdose at week 43, 1 due to coronary artery disease at week 44) were reported on Step 2, and both were determined by the site investigators to be not related to study treatment.

rticipant discontinued treatment due to AE (ischemic cerebral infarction/encephalopathy). Two deaths (both on the LAI arm, 1 due to fentanyl overdose at week 43, 1 due to coronary artery disease at week 44) were reported on Step 2, and both were determined by the site investigators to be not related to study treatment. Among the 141 participants who initiated LAI, 84 (60%) had at least one injection site reaction, with the most frequently reported injection site reactions being pain, swelling, tenderness, or nodule (Table 2). Three participants had ≥1 Grade 3 injection site reaction (pain), and only 2 participants discontinued treatment due to injection site reaction (Grade 1 and Grade 2). Four pregnancies occurred on study, with 2 pregnancies in each Step. Both Step 2 pregnancies were in the LAI arm, one of whom experienced virologic failure and developed RAMs (Participant A, Figure 3). All 4 pregnancies resulted in live births, with no congenital abnormalities reported. The LATITUDE trial established the superiority of monthly LAI CAB/RPV over oral ART to reduce regimen failure in PWH who face adherence barriers. Results appeared similar within subgroups in a vulnerable population that is frequently excluded from clinical trials. While a growing body of observational data reporting benefits of this approach have recently accrued, this study provides randomized clinical trial data indicating efficacy of LAI ART as a treatment strategy to reduce regimen failure in PWH for whom oral ART has not proven effective.

ntly excluded from clinical trials. While a growing body of observational data reporting benefits of this approach have recently accrued, this study provides randomized clinical trial data indicating efficacy of LAI ART as a treatment strategy to reduce regimen failure in PWH for whom oral ART has not proven effective. This trial was launched when HIV treatment guidelines limited LAI to PWH with sustained viral suppression on oral ART. Thus, to foster viral suppression in the viremic population enrolled, the trial provided comprehensive adherence support and financial incentives contingent on viral load reduction during Step 1. Adherence support to individuals in this study reflected routine clinical practice and provision of financial incentives tied to virologic benchmarks in a viremic population has implementation precedence.19,20 However, the utility of alternative strategies to best initiate individuals with viremia on LAI regimens will benefit from further systematic research. To date, “direct-to-inject” approaches show promise in clinical cohorts7-9 , and our study demonstrated no virologic failure or treatment discontinuation for 23 of the 24 participants who initiated LAI without viral suppression. An ongoing study is further evaluating the use of LAI administered every other month versus oral SOC in viremic PWH (NCT06694805).

show promise in clinical cohorts7-9 , and our study demonstrated no virologic failure or treatment discontinuation for 23 of the 24 participants who initiated LAI without viral suppression. An ongoing study is further evaluating the use of LAI administered every other month versus oral SOC in viremic PWH (NCT06694805). The main risk factors present in the five LAI participants experiencing virologic failure were higher BMI and lower CAB and RPV concentrations earlier in treatment, which have been identified in other studies17,18. Additionally needle lengths <2” were used in these participants. This inverse relationship between BMI and trough concentrations is known21, and thus longer needle lengths of 2” are typically recommended to ensure adequate drug exposure. While comparative thresholds to historical PK data were used in our analysis,18,22 a threshold clearly associated with virologic breakthrough has not been identified. Notably none of the participants with virologic failure had missed injections, and three had short delays ≤ 5 days in LAI administration at a maximum of 2 time points.

ive thresholds to historical PK data were used in our analysis,18,22 a threshold clearly associated with virologic breakthrough has not been identified. Notably none of the participants with virologic failure had missed injections, and three had short delays ≤ 5 days in LAI administration at a maximum of 2 time points. Our study is strengthened by the broad study population of individuals in whom viral suppression has not been achieved due to mental health comorbidities, substance and alcohol use, and unstable housing, among other causes, representative of the out-of-care population in the United States23 (Supplementary Appendix). This is reflected in the finding of almost 40% of those randomized to SOC had regimen failure during the study. This emphasizes the potential public health contributions of LAI to ending the HIV epidemic. Protocol modifications were made to address slow accrual, lower than expected transition from Step 1 into Step 2, and to overcome barriers imposed by the COVID-19 public health emergency. While these factors could have introduced heterogeneity in the study population, the results from the subgroup and stratified analyses by protocol version indicated no substantial variability. Similarly, while the use of conditional economic incentives could raise concerns about the generalizability of this strategy, the financial support was time-limited and was not included in Step 2, thus allowing for a direct comparison between LAI and oral SOC.

s by protocol version indicated no substantial variability. Similarly, while the use of conditional economic incentives could raise concerns about the generalizability of this strategy, the financial support was time-limited and was not included in Step 2, thus allowing for a direct comparison between LAI and oral SOC. Our study results showed that LAI has superior efficacy over SOC in reducing regimen failure in PWH who face adherence barriers. This strategy provides a key intervention for both averting disease progression and preventing HIV transmission. Wide implementation of this treatment strategy in the people who need it most will require a multidisciplinary approach to maximize its benefit and reach.

The primary outcome of regimen failure was observed in 29 (19%) participants on LAI and 55 (36%) participants on SOC (Figure 2A). Among LAI regimen failures, 5 had virologic failure as the first event and 24 had permanent treatment discontinuation as the first event. Among SOC failures, 32 had virologic failure as the first event and 23 had permanent treatment discontinuation as the first event. The difference in the Week 48 cumulative probability of regimen failure (LAI - SOC) was −18.4% (98.4% CI: −32.4%, −4.3%, p=0.002) demonstrating superiority of the LAI regimen (Figures 2A/2B). Results of subgroup analyses and supportive analyses are shown in supplemental tables. Six LAI and 34 SOC participants had virologic failure. The treatment difference in the Week 48 cumulative probability of virologic failure was −21.4% (98.4% CI: −33.5%, −9.3%). Nine LAI and 34 SOC participants had treatment-related failure. The difference in the Week 48 cumulative probability of treatment-related failure was −19.2% (98.4% CI: −31.6%, −6.9%). Twenty-six LAI and 37 SOC participants had permanent treatment discontinuation. The treatment difference in the Week 48 cumulative probability of permanent treatment discontinuation was −8.4% (98.4% CI: −21.3%, 4.5%).

Six participants randomized to LAI experienced virologic failure. One of these initiated oral lead-in but discontinued treatment prior to initiating injections (meeting primary outcome), and was followed in the study with subsequent virologic failure. Of the remaining 5 participants, none had a detectable HIV-1 RNA at LAI initiation, nor any missed injections (Figure 3). Three had delayed injections at least once, though all were delayed by <5 days. While guidelines suggest those with BMI >30 kg/m2 should receive injections with 2” needle lengths,10 the 4 virologic failure participants with BMI >30 kg/m2 received injections with needle lengths of ≤1.6”. All except one virologic failure occurred after week 24 on Step 2. All 4 virologic failure s with successful sub-typing of virus were clade B. All participants with virologic failure subsequently suppressed on oral ART except 1 participant who was lost to follow-up (no RAMs were identified at their virologic failure confirmation visit). Plasma concentrations of CAB and RPV were all above the lowest quartile at the time of initial and confirmed virologic failure, consistent with previously reported adequate exposure (Figure 3).17,18 However, each participant demonstrated trends in trough concentrations below the lowest quartile for at least one of the agents early after initiating LAI, some of which were also accompanied by a single detectable viral load that re-suppressed by the subsequent visit.

Fifty-two (34%) LAI and 46 (30%) SOC participants had ≥1 AE during Step 2 (Table 2). The difference in the week 48 cumulative probability of AE was 1.1% (95% CI: −12.7%, 15.0%). Twenty-one (14%) LAI and 16 (10%) SOC participants had ≥1 serious AE reported during Step 2 with the difference in the week 48 cumulative probability of 4.8% (95% CI: −5.6%, 15.2%). Four LAI participants discontinued treatment due to AE, two due to low-grade injection site pain or pain/nodule, one due to seizure, and one due to cerebrovascular accident/hemiparesis requiring anti-coagulation that was deemed by the site investigator as not related to study treatment. Only 1 SOC participant discontinued treatment due to AE (ischemic cerebral infarction/encephalopathy). Two deaths (both on the LAI arm, 1 due to fentanyl overdose at week 43, 1 due to coronary artery disease at week 44) were reported on Step 2, and both were determined by the site investigators to be not related to study treatment.

Among the 141 participants who initiated LAI, 84 (60%) had at least one injection site reaction, with the most frequently reported injection site reactions being pain, swelling, tenderness, or nodule (Table 2). Three participants had ≥1 Grade 3 injection site reaction (pain), and only 2 participants discontinued treatment due to injection site reaction (Grade 1 and Grade 2).

Four pregnancies occurred on study, with 2 pregnancies in each Step. Both Step 2 pregnancies were in the LAI arm, one of whom experienced virologic failure and developed RAMs (Participant A, Figure 3). All 4 pregnancies resulted in live births, with no congenital abnormalities reported.

The LATITUDE trial established the superiority of monthly LAI CAB/RPV over oral ART to reduce regimen failure in PWH who face adherence barriers. Results appeared similar within subgroups in a vulnerable population that is frequently excluded from clinical trials. While a growing body of observational data reporting benefits of this approach have recently accrued, this study provides randomized clinical trial data indicating efficacy of LAI ART as a treatment strategy to reduce regimen failure in PWH for whom oral ART has not proven effective. This trial was launched when HIV treatment guidelines limited LAI to PWH with sustained viral suppression on oral ART. Thus, to foster viral suppression in the viremic population enrolled, the trial provided comprehensive adherence support and financial incentives contingent on viral load reduction during Step 1. Adherence support to individuals in this study reflected routine clinical practice and provision of financial incentives tied to virologic benchmarks in a viremic population has implementation precedence.19,20 However, the utility of alternative strategies to best initiate individuals with viremia on LAI regimens will benefit from further systematic research. To date, “direct-to-inject” approaches show promise in clinical cohorts7-9 , and our study demonstrated no virologic failure or treatment discontinuation for 23 of the 24 participants who initiated LAI without viral suppression. An ongoing study is further evaluating the use of LAI administered every other month versus oral SOC in viremic PWH (NCT06694805).