The virological efficacy of ibalizumab has been clearly demonstrated in multiple clinical trials. This study will expand ibalizumab's clinical data set and allow a better understanding of the virologic response durability on ARV regimens with or without ibalizumab in a heterogeneous real-world patient population. Additional data on the efficacy and safety of ibalizumab and its impact on patient reported outcomes will be captured until study end.

Primary Objective:

To evaluate the long-term efficacy, safety, and durability of ibalizumab in combination with other ARVs by comparing the virologic, immunologic and clinical outcomes of patients receiving ibalizumab treatment versus patients not receiving ibalizumab.

Secondary Objective:

To assess the efficacy of ibalizumab in combination with other antiretrovirals by comparing the virologic, immunologic, clinical and patient reported outcomes of patients before and after they receive ibalizumab treatment.

To assess the long-term safety and tolerability of ibalizumab.

Other Objectives:

To assess risk factors/predictors of virologic and immunologic response. To assess efficacy and safety in special populations that enroll.

Antiretroviral therapy (ART) for treatment of human immunodeficiency virus (HIV) has evolved tremendously over recent years. Newer medications have superior efficacy and tolerability, affording more convenient treatment regimens. The proportion of patients receiving antiretroviral (ARV) treatment that maintain viral suppression is approximately 85% in the United States. However, some patients may not be able to adhere to the prescribed ARV regimen or harbour strains of HIV that are resistant to most currently available therapies. Multi-drug resistant (MDR) HIV may be transmitted or result from incomplete viral suppression, which leads to accumulation of mutations in the viral genome over time. Patients with MDR HIV infection have significantly fewer available treatment options to construct a fully suppressive regimen. This ultimately results in shorter life expectancy, greater potential for transmission of MDR virus, increased morbidity and greater use of health resources. These comparisons are valid for the general population as well as people infected with non-MDR virus.

Ibalizumab, a humanized IgG4 monoclonal antibody that binds to a conformational epitope on domain 2 of the extracellular portion of the CD4 receptor, belongs to a new class of ARVs, CD4-directed post-attachment HIV-1 inhibitors, Ibalizumab exhibits no known cross-resistance with other ARV medications. Ibalizumab was approved by the FDA on March 6, 2018 and is indicated in combination with other ARVs for the treatment of HIV-1 infection in heavily treatment-experienced adults with MDR HIV-1 infection failing their current ARV regimen. It has been available commercially from April 2018.

The safety, efficacy and durability of response to ibalizumab treatment in combination with other ARVs have been demonstrated in clinical trials. This registry is designed to better understand the long-term efficacy and safety outcomes of MDR patients with and without ibalizumab in a real-world scenario.

Inclusion Criteria:

1. The patient is Heavily treatment-experienced (HTE), with limited treatment options and a history of treatment failure;
2. Based on recent or historical resistance assays and ARV history, patients must have documented Multi Drug Resistant (MDR) HIV-1 (e.g., laboratory report and documented past ARV treatment);
3. Received an appropriate HIV-1 resistance assay (genotypic or phenotypic testing) to devise an OBR (which may include an investigational ARV treatment) or will receive an appropriate resistance assay prior to initiating ibalizumab treatment;
4. Provide signed and dated informed consent to the Investigator, indicating that the patient (or, legally acceptable representative) has been informed of all pertinent aspects of the study, and is capable of understanding and willing to comply with the registry requirements. The consent will request to access the patient's medical, hospital, pharmacy, and vital statistics records as appropriate, as well as historical medical data for the full retrospective time period (01 May 2018 to enrollment). Further, consent will be provided for access to all available historical resistance and ARV treatment data;
5. ≥18 years of age or older at the time of screening;
6. Provide information on at least one alternate contact person of their choice (primary care physician, close relative or emergency contact) who can be contacted, should the patient be lost to follow-up over the course of the study;
7. Acknowledgement that in the event of their death, additional information can be obtained by contacting their primary care physician, a close relative, emergency contact or by consulting public or external databases (death registries, obituary listings) when available and verifiable. This is to be done in accordance with local regulatory requirements and laws;
8. Exceptionally, patients who may have started ibalizumab outside of the approved indication can also be included in Cohort 2 of the registry at the discretion of the investigator, provided they determine clinical utility.

Exclusion Criteria:

1. Pregnant or breastfeeding;
2. Unable to provide informed consent;
3. Hypersensitivity to ibalizumab or any of the excipients in ibalizumab;
4. Previous ibalizumab experience (Cohort 1 only)
5. Previously enrolled in Cohort 2 of this registry.

The study will enroll Heavily treatment-experienced (HTE) adult patients infected with MDR HIV-1. For Cohort 2, the study will accept patients prescribed ibalizumab across study sites, including patients previously enrolled in Cohort 1 who subsequently initiated ibalizumab treatment. The decision to include ibalizumab in the treatment regimen will be clinical and independent of patient inclusion in the study.

Yearly interim analyses may be presented at scientific conferences and meetings.