FDA required the sponsor to halt enrollment in the trial and transition participants to available therapies for the treatment of their disease. The trial was subsequently terminated once participants were transitioned.

This study is a Phase 2b/3 multi-center extension study designed to evaluate the long term antiviral activity, safety, and tolerability of the strategy of continuing PRO 140 350mg, 525mg, or 700mg SC (subcutaneous) monotherapy to maintain viral suppression after initial 48 weeks in virologically suppressed subjects.

Consenting subjects will continue weekly PRO 140 350mg, 525mg, or 700mg monotherapy during the Treatment Extension Phase with the one-week overlap of existing retroviral regimen and PRO 140 350mg, 525mg, or 700 mg at the end of the treatment in subjects who do not experience virologic failure.

The objective is to assess the long-term safety of using PRO 140 350mg, 525mg, or 700mg SC as single-agent maintenance therapy for the chronic suppression of CCR5-tropic HIV-1 infection.

Inclusion Criteria:

1. Subjects who have completed 48 weeks of treatment in PRO140_CD03 study.
2. Last known Plasma HIV-1 RNA < 50 copies/mL within PRO140_CD03 study.
3. Both male and female patients and their partners of childbearing potential must agree to use 2 medically accepted methods of contraception (e.g., barrier contraceptives [male condom, female condom, or diaphragm with a spermicidal gel], hormonal contraceptives [implants, injectables, combination oral contraceptives, transdermal patches, or contraceptive rings], and intrauterine devices) during the course of the study (excluding women who are not of childbearing potential and men who have been sterilized). Females of childbearing potential must have a negative serum pregnancy test at Screening visit and negative urine pregnancy test prior to receiving the first dose of study drug.
4. Willing and able to participate in all aspects of the study, including use of SC medication, completion of subjective evaluations, attendance at scheduled clinic visits, and compliance with all protocol requirements as evidenced by providing written informed consent.

Exclusion Criteria:

1. Not currently enrolled in PRO140_CD03 study.

2. Any active infection or malignancy requiring acute therapy (with the exception of local cutaneous Kaposi's sarcoma).

3. Females who are pregnant, lactating, or breastfeeding, or who plan to become pregnant during the study.

4. Subjects weighing < 35kg.

5. History of anaphylaxis to any oral or parenteral drugs.

6. History of Bleeding Disorder or patients on anti-coagulant therapy (except aspirin).

   Note: Subjects with well-controlled bleeding disorder while on stable anti-coagulant therapy dose with documented stable INRs can be enrolled as per discretion of the Investigator.

7. Any other clinical condition that, in the Investigator's judgment, would potentially compromise study compliance or the ability to evaluate safety/efficacy.

All patients who received at least one dose of PRO 140 (leronlimab) were included in the baseline analysis population. Study was early terminated.

Report initiation for all adverse events began at the time of the first treatment extension visit and continued up until the final study visit (up to approximately 197 weeks).

AEs were elicited through direct questioning and subject reports. Any abnormalities in visit evaluations, physical examination findings or laboratory results that the Investigator believed clinically significant to the research subject and that occurred after initiation of the first study treatment were reported as AEs.

FDA required the sponsor to halt enrollment in the trial and transition participants to available therapies for the treatment of their disease. The trial was subsequently terminated once participants were transitioned.