Suppression of human and simian immunodeficiency virus replication with the CCR5-specific antibody Leronlimab in two species

Abstract

The CCR5-specific antibody Leronlimab is being investigated as a novel immunotherapy that can suppress HIV replication with minimal side effects. Here we studied the virological and immunological consequences of Leronlimab in chronically CCR5-tropic HIV-1 infected humans (n = 5) on suppressive antiretroviral therapy (ART) and in ART-naïve acutely CCR5-tropic SHIV infected rhesus macaques (n = 4). All five human participants transitioned from daily combination ART to self-administered weekly subcutaneous (SC) injections of 350 mg or 700 mg Leronlimab and to date all participants have sustained virologic suppression for over seven years. In all participants, Leronlimab fully occupied CCR5 receptors on peripheral blood CD4+ T cells and monocytes. In ART-naïve rhesus macaques acutely infected with CCR5-tropic SHIV, weekly SC injections of 50 mg/kg Leronlimab fully suppressed plasma viremia in half of the macaques. CCR5 receptor occupancy by Leronlimab occurred concomitant with rebound of CD4+ CCR5+ T-cells in peripheral blood, and full CCR5 receptor occupancy was found in multiple anatomical compartments. Our results demonstrate that weekly, self-administered Leronlimab was safe, well-tolerated, and efficacious for long-term virologic suppression and should be included in the arsenal of safe, easily administered, longer-acting antiretroviral treatments for people living with HIV-1. Trial Registration: ClinicalTrials.gov Identifiers: NCT02175680 and NCT02355184.

Fig 1. Leronlimab maintained virologic suppression in humans for over seven years.

(A) Study outline for CD01 and CD01-Extension studies (ClinicalTrials.gov: NCT02175680 and NCT02355184). One-week prior to ART interruption, cohort 1 (n = 2; red) and cohort 2 (n = 3; blue) received weekly SC 350 mg injections. After weeks 246–249, cohort 2 switched to weekly SC 700 mg. Longitudinal HIV-1 RNA copies/mL in plasma for (B) cohort 1 and (C) cohort 2. (D) Total number and (E) mean (±SEM) HIV-1 RNA copies/mL of viral blips (>40 copies/mL). (B-C, E) Horizontal dashed line denotes assay limit of detection (LOD) of 40 copies/mL; undetected viral loads graphed at LOD. (F-G) Left graph shows longitudinal CD4+ T-cell counts in the blood and right graph shows mean (±SD) for all CD4+ T-cell timepoints based on the treatment dose for cohort 1 (E) and cohort 2 (F). (F-G) Two horizontal dotted lines represent the normal range for CD4+ T-cells. Gray and orange boxes denote 350 and 700 mg injections, respectively. (E, G) Two-tailed unpair t test.

Fig 2. Analyses of long-term Leronlimab treatment in humans.

Blood was collected from 01–037, 01–038, 01–057, 01–061, and 01–064 at weeks 304, 301, 297, 299, and 297, respectively. (A) Integrated HIV-1 DNA copies in CD4+ T-cells. (B) Leronlimab concentration in the plasma. Horizontal dashed line denotes LOD (0.0226 μg/mL). (C) CCR5 RO by Leronlimab on CD4+ T-cells, CD8+ T-cells, and CD14+ monocytes. Intracellular cytokine staining of CD95+ memory (D) CD4+ and (E) CD8+ T_M-cells stimulated with HCMV (IE1 and PP65) and HIV (Gag and Nef) peptides. Positive responses were determined by Boolean gating with CD69+TFN-α+ and/or CD69+IFN-γ+.

Fig 3. Leronlimab suppressed SHIV_SF162P3 viremia in macaques.

Macaques were infected intravenously with 1,000 TCID₅₀ SHIV_SF162P3. Leronlimab-treated group (n = 4, green) received weekly SC 50 mg/kg starting at week-3 post-infection and untreated controls (n = 5, black). (A) Study outline. (B) Longitudinal CCR5 RO levels by Leronlimab on blood CD4+CCR5+T-cell. (C) Longitudinal plasma concentration; horizontal dashed line denotes LOD (0.0226 μg/mL). (D) Longitudinal SHIV_SF162P3 RNA copies/mL in plasma. Horizontal dashed line denotes LOD (50 copies/mL); undetectable viral loads graphed at LOD. (E) Longitudinal fold change from week-0 (baseline) for CD4+CCR5+ T-cell percentage in blood. (D-E) Weekly P-values can be found in S4 Table. (F-G) Mean (±SEM) cell-associated SHIV_SF162P3 (F) vDNA and (G) vRNA at week-3 (pre-treatment) and week-15 (necropsy). Horizontal dashed lines denote LOD (7 copies/10⁶ cells). PBMC = peripheral blood mononuclear cell, AxLN = axillary lymph node, MesLN = mesenteric lymph node. (F-G) P-values calculated by two-way repeated-measures ANOVA with Tukey-Kramer adjustment. Gray box represents period of Leronlimab injections.

Fig 4. Tissue penetrance by Leronlimab.

Tissues were collected at week-15 (necropsy). Tissue concentration in A) non-brain and (B) brain tissues. (C) CCR5 RO by Leronlimab on CD4+ T-cells. Panels A-C show mean (±SEM). (D) Representative flow cytometry plots showing the costaining of anti-CCR5 (clone 3A9) and Leronlimab (by anti-human IgG4, clone HP-6025) on CD4+ T-cells from control (38224) and Leronlimab-treated (35778) macaques. PBMC = peripheral blood mononuclear cell, Ax LN = axillary lymph node, Ing LN = inguinal lymph node, Mes LN = mesenteric lymph node, BAL = bronchoalveolar lavage.