Targeted Killing of Virally Infected Cells by Radiolabeled Antibodies to Viral Proteins

BACKGROUND: The HIV epidemic is a major threat to health in the developing and western worlds. A modality that targets and kills HIV-1-infected cells could have a major impact on the treatment of acute exposure and the elimination of persistent reservoirs of infected cells. The aim of this proof-of-principle study was to demonstrate the efficacy of a therapeutic strategy of targeting and eliminating HIV-1-infected cells with radiolabeled antibodies specific to viral proteins in vitro and in vivo. METHODS AND FINDINGS: Antibodies to HIV-1 envelope glycoproteins gp120 and gp41 labeled with radioisotopes bismuth 213 ((213)Bi) and rhenium 188 ((188)Re) selectively killed chronically HIV-1-infected human T cells and acutely HIV-1-infected human peripheral blood mononuclear cells (hPBMCs) in vitro. Treatment of severe combined immunodeficiency (SCID) mice harboring HIV-1-infected hPBMCs in their spleens with a (213)Bi- or (188)Re-labeled monoclonal antibody (mAb) to gp41 resulted in a 57% injected dose per gram uptake of radiolabeled mAb in the infected spleens and in a greater than 99% elimination of HIV-1-infected cells in a dose-dependent manner. The number of HIV-1-infected thymocytes decreased 2.5-fold in the human thymic implant grafts of SCID mice treated with the (188)Re-labeled antibody to gp41 compared with those treated with the (188)Re-control mAb. The treatment did not cause acute hematologic toxicity in the treated mice. CONCLUSIONS: The current study demonstrates the effectiveness of HIV-targeted radioimmunotherapy and may provide a novel treatment option in combination with highly active antiretroviral therapy for the eradication of HIV

Short Communication: Methamphetamine Treatment Increases in Vitro and in Vivo HIV Replication

To delineate the mechanistic basis for the epidemiological association between methamphetamine use and accelerated progression to AIDS, we evaluated the direct in vitro and in vivo effects of methamphetamine on HIV-1 replication. Methamphetamine administration significantly increased HIV-1 production by both HIV-infected monocytes and CD4 T lymphocytes in vitro. In addition, in vivo methamphetamine treatment increased HIV production and viremia in mice transgenic for a replication-competent HIV provirus and human cyclinT1. Methamphetamine activated transcription of the HIV long terminal repeat (LTR) regulatory region, was associated with nuclear translocation of NF-κB. Our results provide further insights into the mechanisms by which methamphetamine accelerates disease course in HIV-infected individuals

Pharmacokinetics of Oral Nirmatrelvir/Ritonavir, a Protease Inhibitor for Treatment of COVID-19, in Subjects With Renal Impairment

Nirmatrelvir coadministered with ritonavir is highly efficacious in reducing the risk of coronavirus disease 2019 (COVID-19) adverse outcomes among patients at increased risk of progression to severe disease, including patients with chronic kidney disease. Because nirmatrelvir is eliminated by the kidneys when given with ritonavir, this phase I study evaluated the effects of renal impairment on pharmacokinetics, safety, and tolerability of nirmatrelvir/ritonavir. Participants with normal renal function (n = 10) or mild, moderate, or severe renal impairment (n = 8 each) were administered a single 100-mg nirmatrelvir dose with 100 mg ritonavir given 12 hours before, together with and 12 and 24 hours after the nirmatrelvir dose. Systemic nirmatrelvir exposure increased with increasing renal impairment, with mild, moderate, and severe renal impairment groups having respective adjusted geometric mean ratio areas under the plasma concentration-time profile from time 0 extrapolated to infinite time of 124%, 187%, and 304% vs. the normal renal function group. Corresponding ratios for maximum plasma concentration were 130%, 138%, and 148%. Apparent clearance was positively correlated with estimated glomerular filtration rate, and geometric mean renal clearance values were particularly lower for the moderate (47% decrease) and severe (80% decrease) renal impairment groups vs. the normal renal function group. Nirmatrelvir/ritonavir exhibited an acceptable safety profile; treatment-related adverse events were mild in severity, and there were no significant findings regarding laboratory measurements, vital signs, or electrocardiogram assessments. These findings led to a dose reduction recommendation for nirmatrelvir/ritonavir in patients with moderate renal impairment (150/100 mg nirmatrelvir/ritonavir instead of 300/100 mg twice daily for 5 days). NCT04909853

Effect of RIT on Platelet Counts in the Peripheral Blood

<p>Platelet counts in the blood of SCID mice injected intrasplenically with HIV-1-infected hPBMCs and either treated with 160 μCi (5.92 MBq) (20 μg) ¹⁸⁸Re-246-D IP 1 h after infection with hPBMCs (<i>n</i> = 5) or no treatment (<i>n</i> = 5). The blood was collected from the tail vein on days 0, 4, 8, and 15 post-therapy. Each data point represents the mean of platelet counts in a given group of mice, and error bars show standard error of the mean.</p

In Vitro Binding and Killing of HIV-Infected Human PBMCs with Human Monoclonal Antibodies

<div><p>(A) Binding of 246-D human mAbs to HIV gp41 was determined by flow cytometry of hPBMCs infected with the JR-CSF strain of HIV-1. Human mAb 1418 (IgG1) to parvovirus B19 was used as an irrelevant control, and human mAb 447 (IgG3) to the V3 loop of HIV-1 gp120 (26) was used as a positive control for the FACS studies. No significant staining was detected after incubation of HIV-infected cells with the conjugated anti-human IgG in the absence of a primary human mAb. Samples were analyzed in duplicate.</p> <p>(B) HIV-infected hPBMCs were treated with ²¹³Bi-246-D, cold 246-D, and ²¹³Bi-1418 (irrelevant control), and noninfected hPBMCs were treated with ²¹³Bi-246-D. The number of surviving cells was determined by Trypan blue dye exclusion assay. Samples were analyzed in triplicate. Every data point represents the mean of two (A) or three (B) replicates; error bars in (B) show standard error of the mean.</p></div

In Vitro Binding and Killing of ACH-2 Cells with ¹⁸⁸Re- and ²¹³Bi-Labeled Monoclonal Antibodies

<div><p>(A) ACH-2 cells treated with anti-gp120 labeled with ¹⁸⁸Re. The mAb 18B7 radiolabeled with ¹⁸⁸Re was used as a irrelevant control.</p> <p>(B) ACH-2 cells treated with anti-gp120 labeled with ²¹³Bi. The mAb 18B7 radiolabeled with ²¹³Bi was used as an irrelevant control.</p> <p>In both experiments the number of surviving cells was determined by Trypan blue dye exclusion. Samples were done in triplicate. Every data point represents the mean of three replicates and error bars show standard error of the mean.</p></div

RIT of SCID Mice Injected Intrasplenically with HIV-1_JR-CSF-Infected Human PBMCs with ¹⁸⁸Re- and ²¹³Bi-Labeled Human Anti-gp41 mAb 246-D

<div><p>(A) Mice were treated IP 1 h after infection with infected hPBMCs with either 20 μg of cold 246-D (<i>n</i> = 4); 100 μCi (3.7 MBq) (20 μg) of ²¹³Bi-1418 (<i>n</i> = 5) or 80 μCi (2.96 MBq) (20 μg) of ¹⁸⁸Re-1418 (<i>n</i> = 3) as isotype-matching controls; 80 μCi (2.96 MBq) (20 μg) of ¹⁸⁸Re-246-D (<i>n</i> = 4); or 100 μCi (3.7 MBq) (20 μg) of ²¹³Bi-246-D (<i>n</i> = 5). One group was left untreated (<i>n</i> = 4). Another group of mice were given 80 μCi (2.96 MBq) (20 μg) of ¹⁸⁸Re-246-D IP 1 h before infection with infected hPBMCs (<i>n</i> = 4).</p> <p>(B) Mice were injected IP with ¹⁸⁸Re-246-D (20 μg) with activity of 40 μCi (1.48 MBq) (<i>n</i> = 4), with 160 μCi (5.92 MBq) (<i>n</i> = 4), or with 20 μg of cold 246-D (<i>n</i> = 4). A fourth group was untreated (<i>n</i> = 4). The number of HIV-1-infected hPBMCs in the spleens were then determined by limiting dilution coculture and presented as TCID₅₀/10⁶ splenocytes. Each bar represents the mean of TCID₅₀/10⁶ splenocytes in a given group of mice, and error bars show standard error of the mean.</p></div

RIT Using Anti-gp41 mAb ¹⁸⁸Re-246-D Reduces HIV Infection in the Human Thymic Implants of thy/liv-SCID-hu Mice

<div><p>One week after thy/liv-SCID-hu mice were infected with HIV-1, they were treated by intraimplant injection of two doses of either ¹⁸⁸Re-246-D (<i>n</i> = 4) or ¹⁸⁸Re-1418 control mAb (<i>n</i> = 4) given on two consecutive days (<i>p</i> = 0.11).</p> <p>(A) The number of HIV-infected thymocytes was determined 3 d later. The bars show mean number (error bars show standard error of the mean) of HIV-infected thymocytes/10⁶ thymocytes in the human thymic implants of thy/liv-SCID-hu mice treated with ¹⁸⁸Re-246-D or ¹⁸⁸Re-1418 control mAb.</p> <p>(B) Comparison of the number of HIV-infected thymocytes in the human thymic implants in each of the four treated thy/liv-SCID-hu mice before treatment was initiated and after treatment with ¹⁸⁸Re-246-D.</p></div