Leronlimab (PRO 140) is a humanized IgG4,k monoclonal antibody (mAb) that recognizes the C-C chemokine receptor type 5 (CCR5). CCR5 is expressed predominantly on T cells but also found on macrophages, dendritic cells, and eosinophils to mediate chemotaxis in response to its cognate ligands that include CCL5 (RANTES), CCL3 (MIP-1α), and CCL4 (MIP-1β). These ligands are integral in the recruitment of these immune cells to inflammatory sites. The immunopathogenesis of COVID-19 likely involves the excessive influx of immune cells into the lung. Disruption of the CCL5-CCR5 axis via leronlimab-mediated CCR5 blockade might prevent pulmonary trafficking of pro-inflammatory leukocytes and dampen pathogenic immune activation in COVID-19. The purpose of the study is to assess the safety and efficacy of leronlimab plus standard of care in patients hospitalized with COVID-19 pneumonia who are not requiring mechanical ventilation or extracorporeal oxygenation (ECMO). This is a Phase 3, 2-arm, randomized, double blind, placebo controlled, multicenter study to evaluate the safety and efficacy of leronlimab (PRO 140) as an add on therapy to the institutional standard of care (SoC) for the management of moderately ill patients with COVID-19 pneumonia. Patients will be randomized in a 1:1 ratio to receive up to four doses of leronlimab (PRO 140) or placebo. Leronlimab (700 mg followed by 350 mg weekly) or placebo will be administered subcutaneously over a 4-week treatment period. No treatments will be administered post-discharge. The participant will be evaluated on each study day while hospitalized up until and including Day 28. The daily visits will capture clinical status - ordinal scale and the occurrence of adverse events. A complete follow-up assessment will be performed at Days 7, 14, 21, 28, 42 and 60 for those who are hospitalized at these specific timepoints. Follow-up visits can be conducted as telephone or video contact visits, if subject is discharged from the hospital prior to the complete follow-up visits.

This is a Phase 2, two-arm, randomized, double blind, placebo controlled multicenter study to evaluate the safety and efficacy of leronlimab (PRO 140) in patients with mild-to-moderate symptoms of respiratory illness caused by coronavirus 2019 infection. Patients will be randomized to receive weekly doses of 700 mg leronlimab (PRO 140), or placebo. Leronlimab (PRO 140) and placebo will be administered via subcutaneous injection. The study will have three phases: Screening Period, Treatment Period, and Follow-Up Period. A total of 75 subjects will be randomized 2:1 in this study.

BACKGROUND: Leronlimab, a monoclonal antibody blocker of CCR5 originally developed to treat HIV-1 infection, was administered as an open label compassionate use therapeutic for COVID-19. METHODS: 23 hospitalized severe/critical COVID-19 patients received 700mg leronlimab subcutaneously, repeated after seven days in 17/23 patients still hospitalized. 18/23 received other experimental treatments, including convalescent plasma, hydroxychloroquine, steroids, and/or tocilizumab. 5/23 received leronlimab after blinded placebo-controlled trials of remdesivir, sarilumab, selinexor, or tocilizumab. Outcomes and results were extracted from medical records. RESULTS: Mean age was 69.5±14.9 years. 20/23 had significant co-morbidities. At baseline, 22/23 were receiving supplemental oxygen (3/23 high flow, 7/23 mechanical ventilation). Blood showed markedly elevated inflammatory markers (ferritin, D-dimer, C-reactive protein) and elevated neutrophil:lymphocyte ratio. By day 30 after initial dosing, 17/23 were recovered, 2/23 were still hospitalized, and 4/23 had died. Of the 7 intubated at baseline, 4/7 were fully recovered off oxygen, 2/7 were still hospitalized, and 1/7 had died. CONCLUSIONS: Leronlimab appeared safe and well tolerated. The high recovery rate suggested benefit, and those with lower inflammatory markers had better outcomes. Some but not all patients appeared to have dramatic clinical responses, indicating that unknown factors may determine responsiveness to leronlimab. Routine inflammatory and cell prognostic markers did not markedly change immediately after treatment, although IL-6 tended to fall. In some persons C-reactive protein clearly dropped only after the second leronlimab dose, suggesting that a higher loading dose might be more effective. Future controlled trials will be informative.

Leronlimab (PRO 140) is a humanized IgG4,k monoclonal antibody (mAb) that recognizes the C-C chemokine receptor type 5 (CCR5). CCR5 is expressed predominantly on T cells but also found on macrophages, dendritic cells, and eosinophils to mediate chemotaxis in response to its cognate ligands that include CCL5 (RANTES), CCL3 (MIP-1α), and CCL4 (MIP-1β). These ligands are integral in the recruitment of these immune cells to inflammatory sites. The immunopathogenesis of COVID-19 likely involves the excessive influx of immune cells into the lung. Disruption of the CCL5-CCR5 axis via leronlimab-mediated CCR5 blockade might prevent pulmonary trafficking of pro-inflammatory leukocytes and dampen pathogenic immune activation in COVID-19. The purpose of the study is to assess the safety and efficacy of leronlimab plus standard of care in critically ill patients hospitalized with COVID-19 pneumonia who are requiring mechanical ventilation or extracorporeal oxigenation (ECMO). This is a Phase 3, 2-arm, randomized, double blind, placebo controlled, multicenter study to evaluate the safety and efficacy of leronlimab (PRO 140) as an add on therapy to the institutional standard of care (SoC) for the management of critically ill patients with COVID-19 pneumonia. Patients will be randomized in a 1:1 ratio to receive up to four doses of 700 mg leronlimab (PRO 140) or placebo. Leronlimab or placebo will be administered by 30-minute intravenous (IV) infusion weekly over a 4-week treatment period. No treatments will be administered post-discharge. The participant will be evaluated on each study day while hospitalized up until and including Day 28. The daily visits will capture clinical status - ordinal scale and the occurrence of adverse events. A complete follow-up assessment will be performed at Days 7, 14, 21, 28, 42 and 60 for those who are hospitalized at these specific timepoints. Follow-up visits can be conducted as telephone or video contact visits, if subject is discharged from the hospital prior to the complete follow-up visits.

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This is a Phase 2, two-arm, randomized, double blind, placebo controlled multicenter study to evaluate the safety and efficacy of leronlimab (PRO 140) in patients with prolonged symptoms caused by Coronavirus Disease 2019 (COVID-19). Patients will be randomized to receive weekly doses of 700 mg leronlimab (PRO 140), or placebo. Leronlimab (PRO 140) and placebo will be administered via subcutaneous injection. The study will have three phases: Screening Period, Treatment Period, and Follow-Up Period. Total study duration is 91 days. The study will be conducted at up to 5 centers in the United States and planned number of subjects are 50 subjects. Visit schedule: Visit 1 - Screening assessment Visit 2 - baseline, first dose Visit 3 - no dose, baseline+3 days Visit 4 - second dose, baseline + 7 days Visit 5 - no dose, safety assessment/con med, baseline +10 days Visit 6 - third dose, baselines + 14 days Visit 7 - no dose, safety assessments, baseline + 17 days Visit 8 - fourth dose, baseline +21 days Visit 9 - no dose, safety assessment, baseline + 24 days Visit 10 - fifth dose, baseline + 28 days Visit 11 - no dose, safety assessment, baseline + 31 days Visit 12 - sixth dose, baseline + 35 days Visit 13 - no dose, safety assessment, baseline + 38 days Visit 14 - seventh dose, baseline + 42 days Visit 15 - no dose, safety assessment, baseline + 45 days Visit 16 - eighth and final dose, baseline + 49 days Visit 17 - End of treatment, baseline + 56 days

This is a Phase 2b/3, two-arm, randomized, double blind, placebo controlled, adaptive design multicenter study to evaluate the safety and efficacy of leronlimab (PRO 140) in patients with severe or critical symptoms of respiratory illness caused by coronavirus 2019 infection. Patients will be randomized to receive weekly doses of 700 mg leronlimab (PRO 140), or placebo. Leronlimab (PRO 140) and placebo will be administered via subcutaneous injection. A single arm, non-randomized, open-label phase is added to the protocol after completion of enrollment in the Randomized Phase of the study. The study will have three phases: Screening Period, Treatment Period, and Follow-Up Period.

Coronavirus disease 2019 (COVID-19) is associated with considerable morbidity and mortality. The number of confirmed cases of infection with SARS-CoV-2, the virus causing COVID-19 continues to escalate with over 70 million confirmed cases and over 1.6 million confirmed deaths. Severe-to-critical COVID-19 is associated with a dysregulated host immune response to the virus, which is thought to lead to pathogenic immune dysregulation and end-organ damage. Presently few effective treatment options are available to treat COVID-19. Leronlimab is a humanized IgG4, kappa monoclonal antibody that blocks C-C chemokine receptor type 5 (CCR5). It has been shown that in patients with severe COVID-19 treatment with leronlimab reduces elevated plasma IL-6 and chemokine ligand 5 (CCL5), and normalized CD4/CD8 ratios. We administered leronlimab to 4 critically ill COVID-19 patients in intensive care. All 4 of these patients improved clinically as measured by vasopressor support, and discontinuation of hemodialysis and mechanical ventilation. Following administration of leronlimab there was a statistically significant decrease in IL-6 observed in patient A (p=0.034) from day 0-7 and patient D (p=0.027) from day 0-14. This corresponds to restoration of the immune function as measured by CD4+/CD8+ T cell ratio. Although two of the patients went on to survive the other two subsequently died of surgical complications after an initial recovery from SARS-CoV-2 infection.

BACKGROUND: Triple-negative breast cancer (BCa) (TNBC) is a deadly form of human BCa with limited treatment options and poor prognosis. In our prior analysis of over 2200 breast cancer samples, the G protein-coupled receptor CCR5 was expressed in > 95% of TNBC samples. A humanized monoclonal antibody to CCR5 (leronlimab), used in the treatment of HIV-infected patients, has shown minimal side effects in large patient populations. METHODS: A humanized monoclonal antibody to CCR5, leronlimab, was used for the first time in tissue culture and in mice to determine binding characteristics to human breast cancer cells, intracellular signaling, and impact on (i) metastasis prevention and (ii) impact on established metastasis. RESULTS: Herein, leronlimab was shown to bind CCR5 in multiple breast cancer cell lines. Binding of leronlimab to CCR5 reduced ligand-induced Ca+ 2 signaling, invasion of TNBC into Matrigel, and transwell migration. Leronlimab enhanced the BCa cell killing of the BCa chemotherapy reagent, doxorubicin. In xenografts conducted with Nu/Nu mice, leronlimab reduced lung metastasis of the TNBC cell line, MB-MDA-231, by > 98% at 6 weeks. Treatment with leronlimab reduced the metastatic tumor burden of established TNBC lung metastasis. CONCLUSIONS: The safety profile of leronlimab, together with strong preclinical evidence to both prevent and reduce established breast cancer metastasis herein, suggests studies of clinical efficacy may be warranted.

CCR5 plays a central role in infectious disease, host defense, and cancer progression, thereby making it an ideal target for therapeutic development. Notably, CCR5 is the major HIV entry co-receptor, where its surface density correlates with HIV plasma viremia. The level of CCR5 receptor occupancy (RO) achieved by a CCR5-targeting therapeutic is therefore a critical predictor of its efficacy. However, current methods to measure CCR5 RO lack sensitivity, resulting in high background and overcalculation. Here, we report on two independent, flow cytometric methods of calculating CCR5 RO using the anti-CCR5 antibody, Leronlimab. We show that both methods led to comparable CCR5 RO values, with low background on untreated CCR5+CD4+ T cells and sensitive measurements of occupancy on both blood and tissue-resident CD4+ T cells that correlated longitudinally with plasma concentrations in Leronlimab-treated macaques. Using these assays, we found that Leronlimab stabilized cell surface CCR5, leading to an increase in the levels of circulating and tissue-resident CCR5+CD4+ T cells in vivo in Leronlimab-treated macaques. Weekly Leronlimab treatment in a chronically SIV-infected macaque led to increased CCR5+CD4+ T cells levels and fully suppressed plasma viremia, both concomitant with full CCR5 RO on peripheral blood CD4+ T cells, demonstrating that CCR5+CD4+ T cells were protected from viral replication by Leronlimab binding. Finally, we extended these results to Leronlimab-treated humans and found that weekly 700 mg Leronlimab led to complete CCR5 RO on peripheral blood CD4+ T cells and a statistically significant increase in CCR5+CD4+ T cells in peripheral blood. Collectively, these results establish two RO calculation methods for longitudinal monitoring of anti-CCR5 therapeutic antibody blockade efficacy in both macaques and humans, demonstrate that CCR5+CD4+ T cell levels temporarily increase with Leronlimab treatment, and facilitate future detailed investigations into the immunological impacts of CCR5 inhibition in multiple pathophysiological processes.