This study evaluates the real-world effectiveness and safety of a long-acting injectable HIV treatment consisting of cabotegravir and rilpivirine in people living with HIV-1. The focus is on individuals with HIV-1 subtype A6, which is common in Eastern Europe and among people who acquired HIV in that region, and on comparison with individuals with subtype B and those with an unknown subtype.

Although long-acting cabotegravir and rilpivirine are widely used and effective, limited real-world data are available on how well this treatment works in people with HIV-1 subtype A6. This is important because subtype A6 has been suggested as a potential risk factor for treatment failure, but current evidence is inconclusive.

The study uses existing medical records from treatment centers in Poland, Germany, and the Czech Republic. It includes adults with HIV who have received at least one injection of long-acting cabotegravir and rilpivirine and follows their clinical outcomes for up to 24 months. Researchers will assess viral suppression, treatment persistence, adherence to injection schedules, and reasons for treatment discontinuation.

The results of this study will help clinicians better understand whether HIV-1 subtype A6 affects treatment outcomes and whether knowing a patient's HIV subtype is important when deciding to switch to long-acting injectable therapy. The findings may support safer and more effective use of this treatment in diverse patient populations.

This is a multicentre, international, real-world, retrospective observational study designed to evaluate clinical outcomes of long-acting injectable cabotegravir plus rilpivirine (CAB/RPV LA) in adults living with HIV-1. The study is conducted at HIV treatment centers in Poland, Germany, and the Czech Republic and is based on routinely collected clinical data from electronic medical records and paper charts.

The study population includes treatment-experienced individuals aged 18 years or older who received at least one dose of CAB/RPV LA in routine clinical practice. Participants are grouped according to HIV-1 subtype: subtype A6, subtype B, and unknown subtype. Individuals with known subtype A6 are matched with individuals with subtype B using propensity score matching to reduce the impact of confounding factors. Participants with unknown subtype are analyzed as an unmatched group.

Clinical data are collected from the time of CAB/RPV LA initiation (index date) and from follow-up visits closest to 6, 12, 18, and 24 months after initiation. Outcomes assessed include treatment persistence, adherence to injection schedules, discontinuation rates and reasons for discontinuation, and measures of virologic effectiveness. Virologic outcomes include viral suppression, viral rebound, and confirmed virologic failure as defined by standard HIV RNA criteria.

For participants with unknown HIV-1 subtype, proviral DNA genotyping is performed after initial descriptive analyses to explore whether knowledge of HIV-1 subtype has prognostic relevance for clinical outcomes. Genotypic data are analyzed descriptively and may inform additional exploratory analyses.

As this is a retrospective, non-interventional study using existing clinical data, no study-specific treatment interventions are performed. Safety data collection is limited to adverse events leading to treatment discontinuation, reflecting routine clinical practice. The study aims to provide clinically relevant real-world evidence on the use of CAB/RPV LA across different HIV-1 subtypes, with particular focus on subtype A6.

Inclusion Criteria:

• Confirmed diagnosis of HIV-1 infection
• Age ≥18 years at the time of initiation of long-acting cabotegravir plus rilpivirine (CAB/RPV LA)
• Received at least one dose of CAB/RPV LA as part of routine clinical care
• Availability of relevant clinical data in medical records for retrospective analysis
• Signed informed consent for use of clinical data
• Agreement to provide an additional blood sample for proviral DNA genotyping, if HIV-1 subtype was unknown at treatment initiation

Exclusion Criteria:

- Lack of patient consent for use of clinical data for research purposes

The study population consists of adults aged 18 years or older living with HIV-1 infection who have received long-acting injectable cabotegravir plus rilpivirine (CAB/RPV LA) as part of routine clinical care. Participants are treatment-experienced and include individuals with suppressed or unsuppressed HIV-1 viral load at the time of treatment initiation.

Patients are identified retrospectively from electronic medical records at participating HIV treatment centers in Poland, Germany, and the Czech Republic. Participants are grouped according to documented HIV-1 subtype (subtype A6, subtype B, or unknown subtype). Individuals with known subtype A6 are matched with individuals with subtype B based on selected clinical characteristics, while participants with unknown subtype are analyzed as an unmatched descriptive cohort.

The study includes a broad, real-world patient population without upper age limits or sex-based restrictions, reflecting routine clinical practice in participating ce

Individual participant data (IPD) will not be shared because this is a retrospective, observational study based on routinely collected clinical data from multiple centers. The data are pseudo-anonymized and subject to local data protection regulations and ethical approvals, which limit the ability to share individual-level data outside the study team.