This study is designed to assess the safety and pharmacokinetic profile of 800 mg Trogarzo once every two weeks administered via "IV Push" or intramuscular injection. An initial "Sentinel Group" of 5 participants will begin receiving 800mg Trogarzo on a gradual schedule of increasing concentration and decreasing administration time until undiluted IV Push over 30 seconds is achieved, while safety and pharmacokinetics are evaluated. If no safety signals are seen, the Core Group of 15 participants will be enrolled. The Core Group will receive 800mg Trogarzo via undiluted IV Push over 30 seconds while safety and pharmacokinetics are monitored. After completion of the IV Push portion of the study, a second group of 20 participants will be enrolled to evaluate the safety and pharmacokinetics of administration of 800mg via intramuscular injection.

This goal of this Phase 3 is to evaluate the safety and pharmacokinetics of administering Trogarzo 800 mg once every two weeks as an undiluted IV Push over 30 seconds, and as an intramuscular injection in clinically stable HIV-1 infected patients currently receiving treatment with a stable Trogarzo-containing regimen and in healthy volunteers.

The first five (5) patients enrolled will comprise the Sentinel Group. Patients six (6) through twenty (20) (the Core Group) will not be screened until the Sentinel Group has completed Day 99 (14 weeks) of the study and the DSMB has reviewed the data accumulated and given approval for enrollment of the Core Group to proceed.

The Sentinel Group will receive 2 successive doses of Trogarzo in accordance with the prescribing information. Safety and pharmacokinetic data from these administrations will serve as the comparator for each study participant. Beginning at Day 29 and continuing through Day 85, Sentinel Group participants will begin receiving the prescribed dosage of Trogarzo once every two weeks through Day 85 of the study on a schedule of increasing drug concentration and decreasing administration time at each visit to achieve an undiluted IV Push administration of Trogarzo over 30 seconds.

After review of data from the Sentinel Group by a Data Safety Monitoring Board (DSMB), if approved the study will continue with enrollment of the Core Group, which will enroll both clinically stable HIV-infected patients on a stable Trogarzo-containing treatment regimen and healthy volunteers. The HIV-infected participants in the Core Group will receive 2 successive doses of Trogarzo in accordance with the prescribing information. Safety and pharmacokinetic data from these administrations will serve as the comparator for each study participant. Thereafter, HIV-infected participants in the Core Group will receive the prescribed dosage of Trogarzo via undiluted IV Push over 30 seconds through Day 71 of the study.

Healthy Volunteers in the Core Group will receive a single loading dose of 2000mg of Trogarzo, followed by three successive doses of 800mg Trogarzo in accordance with the prescribing information in order to reach steady state before pharmacokinetic data for analysis are collected. Thereafter, Healthy Volunteers in the Core Group will follow the same schedule of drug administration and assessments as the HIV-infected participants in the Core Group.

HIV-infected participants in the Intramuscular Injection Group will receive 2 successive doses of Trogarzo in accordance with the prescribing information. Safety and pharmacokinetic data from these administrations will serve as the comparator for each study participant. Thereafter, HIV-infected Intramuscular Injection Group participants will receive the prescribed dosage of Trogarzo via intramuscular injection beginning at Day 29 and continuing through Day 71.

Healthy Volunteers in the Intramuscular Injection Group will receive a single loading dose of 2000mg of Trogarzo, followed by three successive doses of 800mg Trogarzo in accordance with the prescribing information in order to reach steady state before pharmacokinetic data for analysis are collected. Thereafter, Healthy Volunteers in the Intramuscular Injection Group will follow the same schedule of drug administration and assessments as the HIV-infected participants in the Intramuscular Injection Group.

Inclusion Criteria - HIV-infected participants (all groups):

1. Are capable of understanding and have voluntarily signed the informed consent document
2. Currently receiving a stable Trogarzo-containing antiretroviral (ARV) regimen for a minimum of 3 months, and no change in background ARVs anticipated over the period of study participation; a stable regimen is defined as having no changes in dose or frequency and no interruptions greater than or equal to 2 weeks during the 3 month period
3. Have no acquired immunodeficiency syndrome (AIDS)-defining events in the 3 months before Screening, other than cutaneous Kaposi's sarcoma or wasting syndrome due to HIV
4. Are able and willing to comply with all protocol requirements and procedures
5. Are 18 years of age or older
6. Have a life expectancy that is >6 months.
7. Have a viral load <1,000 copies/mL at Screening
8. CD4+ T-cell count > 50 cells/mm3 at Screening
9. Prothrombin time (PT) and partial thromboplastin time (PTT) <1.5 times the upper limit of normal (IM Group only)

Inclusion Criteria - Healthy Volunteers (all groups):

1. Healthy volunteers born male and female as assessed by medical history and physical examination
2. Aged >18 and <50 years at the time of Screening
3. Ability and willingness to provide written informed consent
4. Willingness to comply with protocol schedule
5. Willingness to undergo HIV-1 testing
6. Non-reactive 4th generation point of care HIV-1 test at Screening
7. Hepatitis B Surface antigen negative
8. Hepatitis C antibody negative, or if reactive, Hepatitis C RNA undetectable in plasma
9. PT and PTT <1.5 times the upper limit of normal (IM Group only)
10. Volunteers born female of reproductive potential who are sexually active with a male sex partner must agree to use one effective method of contraception from the time of signing the consent to completion of the study and agree to pregnancy testing as per the schedule of events.

Volunteers born female with reproductive potential are defined as pre-menopausal volunteers born female who have not had a sterilization procedure (e.g., hysterectomy, bilateral oophorectomy, tubal ligation or salpingectomy). Volunteers born female are considered menopausal if they have not had a menses for at least 12 months and have a follicle-stimulating hormone (FSH) of greater than 40 IU/L or if FSH testing is not available, they have had amenorrhea for 24 consecutive months.

Exclusion Criteria - HIV-infected participants (all groups):

1. Any active AIDS-defining illness according to the Centers for Disease Control and Prevention (CDC) Revised Surveillance Case Definitions for HIV Infection 2008 (Morbidity and Mortality Weekly Report (MMWR) Vol.57/No. RR-10, Appendix A), or history of the same during the 3 months preceding Screening, with the following exceptions: cutaneous Kaposi's sarcoma and wasting syndrome due to HIV

2. Any significant diseases (other than HIV-1 infection) or clinically significant findings, including psychiatric and behavioral problems, determined from Screening, medical history, and/or physical examination that, in the investigator's opinion, would preclude the subject from participating in this study

3. Any significant acute illness within 1 week before the initial administration of study drug

4. Any active infection secondary to HIV requiring acute therapy; however, subjects that require maintenance therapy (i.e., secondary prophylaxis for opportunistic infections) will be eligible for the study

5. Any immunomodulating therapy (including interferon), systemic steroids, or systemic chemotherapy within 12 weeks before Enrollment

6. Any vaccination within 7 days before Day 1

7. Any female subject who either is pregnant, intends to become pregnant, or is currently breastfeeding

8. Any current alcohol or illicit drug use that, in the investigator's opinion, will interfere with the subject's ability to comply with the study schedule and protocol evaluations

9. Any radiation therapy during the 28 days before first administration of study medication

10. Any Grade 3 or 4 laboratory abnormality according to the Division of AIDS (DAIDS) grading scale, except for the following asymptomatic Grade 3 events:

    • triglyceride elevation
    • total cholesterol elevation
    • or Grade 3 or 4 reductions in levels of CD4+ T cells

11. History of coagulopathy that would preclude administration of IM injections (IM Group only)

12. Skin rashes or tattoos that would prevent ability to assess IM injection for injection-site reactions (IM Group only)

13. Use of high-dose aspirin, clopidogrel, prasugrel, ticagrelor, dipyridamole or other antiplatelet medication that would interfere with the ability to receive IM injections (IM Group only).

Exclusion Criteria - Healthy Volunteers (all groups):

1. Confirmed HIV-1 infection

2. At high risk of severe COVID-19 disease as defined by one of the following:

   • History of hypertension, atherosclerotic cardiovascular disease (ASCVD), coronary artery disease, diabetes mellitus
   • History of asthma or chronic pulmonary disease
   • History of renal disease and chronic renal insufficiency
   • BMI over 35

3. Any acute or chronic medical condition that in the opinion of the investigator would preclude participation

4. Chronic autoimmune disease

5. Active IV drug use

6. Excessive use of alcohol or recreational drugs that in the opinion of the investigator would preclude participation

7. Decompensated psychiatric illness

8. Need for chronic immunotherapy including systemic corticosteroids, other monoclonal antibody (MAb) therapy, or immunosuppressive drugs

9. Volunteers born female who are pregnant, lactating, or planning on becoming pregnant over the study period

10. Any of the following laboratory parameters:

    • Hemoglobin <10.0 g/dL
    • Absolute neutrophil count <1,000/mm3
    • Absolute lymphocyte count <500/mm3
    • Platelet count <100,000/mm3
    • Creatinine >1.25x upper limit of normal (ULN)
    • Aspartate aminotransferase (AST) >1.5x ULN
    • Alanine aminotransferase (ALT) >1.5x ULN
    • Glucose (non-fasting) >160 mg/dL
    • Proteinuria: 2+ or greater
    • Hematuria: >10 red blood cells (RBCs) per high-power field

11. Previous receipt of an experimental MAb for HIV-1treatment or prevention in a research study

12. History of severe allergic reactions to drugs, vaccines, or drug infusion

13. Participation in another investigational clinical trial within the past 12 weeks or anticipated during the course of the current study

14. History of coagulopathy that would preclude administration of IM injections (IM Group only)

15. Skin rashes or tattoos that would prevent ability to assess IM injection for injection-site reactions (IM Group only)

16. Use of high-dose aspirin, clopidogrel, prasugrel, ticagrelor, dipyridamole any other antiplatelet medication that would interfere with the ability to receive IM injections (IM Group only).

Individual Participant Data will not be shared with other researchers.

Adverse events were elicited from the time of signing the informed consent through completion of the study at either day 85 (HIV+ IVP, HIV+IM, HIV uninfected IVP) or day 99 (Sentinel IVP and Uninfected IM). For HIV-uninfected individuals study duration requited establishment of an ibalizumab steady state which added 55 days to period of time over which adverse event data were collected.

Adverse events were collected by subject interview, observation pre, during, and post ibalizumab infusion over 15 minute; pre, during and post ibalizumab dosing by intravenous push and pre- during, and post IM administration of ibalizumab.

Limitations of the trial include::

1. difficulty in recruitment of HIV-infected individuals who were using ibalizumab as part of a suppressive regimen as issues with continued supply and reimbursement emerged necessitating the recruitment of HIV-uninfected participants in whom the pharmacokinetics of ibalizumab differ from the HIV-infected population.