The Bovine Tuberculoid Granuloma

The bovine tuberculoid granuloma is the hallmark lesion of bovine tuberculosis (bTB) due to Mycobacterium bovis infection. The pathogenesis of bTB, and thereby the process of bovine tuberculoid granuloma development, involves the recruitment, activation, and maintenance of cells under the influence of antigen, cytokines and chemokines in affected lungs and regional lymph nodes. The granuloma is key to successful control of bTB by preventing pathogen dissemination through containment by cellular and fibrotic layers. Paradoxically, however, it may also provide a niche for bacterial replication. The morphologic and cellular characteristics of granulomas have been used to gauge disease severity in bTB pathogenesis and vaccine efficacy studies. As such, it is critical to understand the complex mechanisms behind granuloma initiation, development, and maintenance.

Translation of Pharmacodynamic Biomarkers of Antibiotic Efficacy in Specific Populations to Optimize Doses

Antibiotic efficacy determination in clinical trials often relies on non-inferiority designs because they afford smaller study sample sizes. These efficacy studies tend to exclude patients within specific populations or include too few patients to discern potential differences in their clinical outcomes. As a result, dosing guidance in patients with abnormal liver and kidney function, age across the lifespan, and other specific populations relies on drug exposure-matching. The underlying assumption for exposure-matching is that the disease course and the response to the antibiotic are similar in patients with and without the specific condition. While this may not be the case, clinical efficacy studies are underpowered to ensure this is true. The current paper provides an integrative review of the current approach to dose selection in specific populations. We review existing clinical trial endpoints that could be measured on a more continuous rather than a discrete scale to better inform exposure–response relationships. The inclusion of newer systemic biomarkers of efficacy can help overcome the current limitations. We use a modeling and simulation exercise to illustrate how an efficacy biomarker can inform dose selection better. Studies that inform response-matching rather than exposure-matching only are needed to improve dose selection in specific populations.

Development of Astatine-211 (211At)-Based Anti-CD123 Radioimmunotherapy for Acute Leukemias and Other CD123+ Hematologic Malignancies

Background: Radioimmunotherapy (RIT) has long been pursued to improve outcomes in acute leukemia. Of current interest are alpha-particle emitting radionuclides as they deliver a very large amount of radiation over just a few cell diameters, enabling efficient and selective target cell kill. So far, alpha-emitters including astatine-211 (211At) have been primarily explored with monoclonal antibodies (mAbs) targeting CD45 or CD33 but their broad display on non-malignant target-expressing cells can lead to marked "on-target, off tumor cell" toxicities. To overcome this limitation, we developed a novel form of 211At-based RIT targeting CD123. CD123 is displayed widely on acute leukemia cells, including underlying leukemic stem cells, but is expressed only on a discrete subset of normal hematopoietic cells and is virtually absent on non-blood cells. Methods: We immunized BALB/c mice with peptides consisting of the extracellular domain of human CD123 to generate anti-CD123 mAbs. Flow cytometry-based assays with human acute leukemia cell lines were used to characterize binding of hybridoma supernatants and mAbs to CD123. mAbs were conjugated with isothiocyantophenethyl-ureido-closo-decaborate(2-) (B10), a boron cage molecule for subsequent astatination, and were then labeled with 211At. In vivo leukemia cell targeting ("biodistribution") and efficacy studies were conducted in immunodeficient NOD-Rag1 null IL2rɣ null/J (NRG) mice xenografted with MOLM-13 cells, a CD123+ human acute myeloid leukemia cell line. Results: Based on initial hybridoma screening studies, we selected 4 mAbs (10C4, 5G4, 11F11, and 1H8) for further characterization. Phenotyping studies with CD123+ and CD123- human acute leukemia cell lines (including CD123+ cell lines in which CD123 was deleted via CRISPR/Cas9) confirmed specific binding of all mAbs to human CD123 (binding intensity: 10C4>5G4=11F11=1H8), with 10C4 yielding a higher median fluorescence intensity than the widely used commercial anti-CD123 mAb clones, 7G3 and 6H6 (Figure 1). In vitro internalization with a panel of human acute leukemia cell lines studies demonstrated uptake of all mAbs by CD123+ target cells with a kinetic slower than that for anti-CD33 antibodies (typically, 30-50% of the anti-CD123 mAb internalized over 2-4 hours). All 4 anti-CD123 mAbs could be conjugated to B10 and subsequently labeled with 211At. Unlike a non-binding 211At-labeled control mAb, 211At-labeled anti-CD123 mAbs showed uptake at MOLM-13 flank tumors in NRG mice carrying MOLM-13 xenografts. After additional leukemia cell targeting studies to optimize the dosing of 10C4, we conducted proof-of-concept efficacy studies in NRG mice injected intravenously with luciferase-transduced MOLM-13 cells (disseminated leukemia model). Animals were either untreated or treated with 10 µCi, 20 µCi, or 40 µCi of 211At-labeled 10C4-B10 mAb (9-11 animals/group). This was followed by the infusion of bone marrow cells from donor mice as stem cell support 3 days later. As shown in Figure 2 and Figure 3, 211At-10C4-B10 led to a dose dependent decrease in tumor burden. Further, the treatment significantly prolonged survival compared to untreated animals (median survival: 49 days [40 µCi of 211At] vs. 31 days [10 µCi of 211At] vs. 21 days [Ctrl]; P<0.0001 for Ctrl vs. 10 µCi, P<0.004 for 10 µCi vs. 40 µCi), demonstrating potent in vivo anti-leukemia efficacy of a single dose of 211At-CD123 RIT. Conclusion: Our data support the further development of 211At-CD123 RIT for the treatment of patients with acute leukemia and other CD123+ hematologic malignancies. Figure 1 Figure 1. Disclosures Green: Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Cellectar Biosciences: Research Funding; GSK: Membership on an entity's Board of Directors or advisory committees; JANSSEN Biotech: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno Therapeutics: Patents & Royalties, Research Funding; Legend Biotech: Consultancy; Neoleukin Therapeutics: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; SpringWorks Therapeutics: Research Funding. Walter: Kite: Consultancy; Janssen: Consultancy; Genentech: Consultancy; BMS: Consultancy; Astellas: Consultancy; Agios: Consultancy; Amphivena: Consultancy, Other: ownership interests; Selvita: Research Funding; Pfizer: Consultancy, Research Funding; Jazz: Research Funding; Macrogenics: Consultancy, Research Funding; Immunogen: Research Funding; Celgene: Consultancy, Research Funding; Aptevo: Consultancy, Research Funding; Amgen: Research Funding.

865 iosH2 exerts potent anti-tumor activity by blocking LILRB1/2 and KIR3DL1 receptor signaling

BackgroundTo develop novel anti-cancer therapeutics we have used a reverse rational approach and searched for human HLA class I molecules known to induce autoimmunity and long-term lasting viral control as a surrogate marker for potential anti-cancer activity. HLA-B*27 or HLA-B*57 are well known genetic factors associated with superior control of viral infections (e.g. HIV and HCV) through processes related to both adaptive and innate immunity. Here we demonstrate that the expression of an optimised HLA-B57-Fc fusion protein (iosH2) exerts anti-tumor efficacy through its multimodal inhibition of LILRB1/2 and KIR3DL1 receptors.Methods iosH2 was produced by stable expression in CHO cells and purified by standard chromatography techniques. Interaction and competition studies were performed using Bio-Layer Interferometry, ELISA, and cell-based assays. Analysis of LILRB1/2 downstream ITIM signaling was assessed using an automated western blot system. Functional cell-based assays including in vitro polarization and phagocytosis of macrophages, T cell and NK cell assays were assessed using live-cell imaging. In vivo efficacy studies were performed using syngeneic and humanized mouse models of cancer.Results iosH2 binds with nanomolar affinity to LILRB1/2 and KIR3DL1, and blocks HLA-G and ANGPTL’s binding to LILRB1/2. iosH2 reduces ITIM downstream signalling including phosphorylation of SHP1/2 and promotes conversion from M2 to M1 macrophage phenotype resulting in enhanced tumor cell phagocytosis in vitro. In addition, iosH2 increases T and NK cell cytotoxicity in co-cultures with cancer cell lines. In vivo efficacy studies demonstrate therapeutic efficacy in syngeneic C38 colon cancer mice and in BRGSF-HIS humanized PDX NSCLC mice in concert with reduction of pro-tumorigenic cytokines.Conclusions iosH2 binds to LILRB1/2 and KIR3DL1, restores immune effector cell function in vitro and demonstrates anti-tumor activity in diverse in vivo mouse models. iosH2 is a first-in-class multi-functional agent that promotes key components of the innate and adaptive immune system leading to profound anti-tumor activity. Clinical development is underway and a phase I trial in preparation.Ethics Approval1. Animal housing and experimental procedures were conducted according to the French and European Regulations and the National Research Council Guide for the Care and Use of Laboratory Animals7–8. The animal facility is authorized by the French authorities (Agreement N° B 21 231 011 EA). All animals procedures (including surgery, anesthesia and euthanasia as applicable) used in the current study (200269/ACT1 C38 SC/Ethical protocol: ONCO 1) were submitted to the Institutional Animal Care and Use Committee of Oncodesign (Oncomet) approved by French authorities (CNREEA agreement N° 91). 2. Animal welfare for this study complies with the UK Animals Scientific Procedures Act 1986 (ASPA) in line with Directive 2010/63/EU of the European Parliament and the Council of 22 September 2010 on the protection of animals used for scientific purposes. All experimental data management and reporting procedures were in strict accordance with applicable Crown Bioscience UK Guidelines and Standard Operating Procedures.

Current guidelines for malaria treatment in Somalia: evidence-based recommendations

Case management – rapid diagnosis and prompt administration of artemisinin-based combination therapy (ACT) – is a fundamental pillar of recommended malaria interventions in Somalia. Unfortunately, the emergence and spread of drug resistant falciparum parasites continues to pose a considerable threat to effective case management. With technical and financial support from WHO, the efficacy of recommended ACTs has been regularly monitored in sentinel sites since 2003. These studies provided evidence that supported the adoption of artesunate-sulfadoxine/pyrimethamine as first-line treatment in 2005 and artemether-lumefantrine as second-line treatment in 2011. Efficacy studies conducted between 2011 and 2015 showed high artesunate-sulfadoxine/pyrimethamine treatment failure rates of 12.3% - 22.2%, above the threshold (10%) for a change of treatment policy as recommended by WHO. This was also associated with high prevalence of quadruple and quintuple mutations in the dihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps) genes, which are associated with sulfadoxine/pyrimethamine resistance. Based on these findings, national malaria treatment guidelines were updated in 2016, with artesunate-sulfadoxine/pyrimethamine replaced by artemether-lumefantrine as first-line treatment and dihydroartemisinin-piperaquine recommended as second-line treatment. Subsequent efficacy studies in 2016 and 2017 confirmed that both the current first- and second-line treatments remain highly efficacious (cure rate above 97%). Technical and financial support from WHO has been instrumental in generating evidence that informs malaria treatment policy and should therefore continue to ensure that effective treatments are available to malaria patients in the country.

Immunogenicity of SCB-2019 COVID-19 Vaccine Compared to Four Approved Vaccines

A significant correlation has been shown between the binding antibody responses against original SARS-CoV-2-S-protein all performed in one laboratory and vaccine efficacy of four approved COVID-19 vaccines. We therefore assessed the immune response against original SARS-CoV-2 elicited by the adjuvanted S-Trimer vaccine, SCB-2019 + CpG/alum, in the same assay and laboratory. When compared with four approved vaccines immune responses to SCB-2019 predicted 81% − 94% efficacy against the original strain and 75–94% against the Alpha variant (B.1.1.7). Immunogenicity comparisons to original strain and variants of concern (VOC) should be considered as a basis for authorization of vaccines because efficacy studies now have predominantly VOC cases.

The Antimicrobial Mode of Action of Maltol and Its Synergistic Efficacy with Selected Cationic Surfactants

Maltol, mostly used as a flavoring molecule, also has various potential applications as a biomedical compound. Despite its extensive use in the food industry, maltol’s antimicrobial activity was evaluated only briefly, and was suggested to be insufficient on its own. Recently, we have shown that maltol can be used in conjunction with cationic surfactant species to receive higher activity against contaminant microorganisms. In this paper, we have broadened the antimicrobial efficacy studies and evidenced maltol’s mode of action against Gram-negative, Gram-positive bacteria, and fungi. In addition, to increase its efficacy, blends of maltol and two selected cationic surfactants, dodecyl-dimethyl-ammonium chloride (DDAC) and polyquaternium 80 (P-80), were appraised for their activity. Broad efficacy studies revealed synergistic interactions between maltol and both cationic surfactants against most of the tested microorganisms. Electron microscopy images were used to evaluate the microorganisms’ morphology following treatment, pinpointing the specific cell wall damage caused by each of the compounds. Our findings indicate that maltol’s effect on the microbial cell wall can be complemented by catalytic amounts of selected cationic surfactants to enhance and extend its activity. Such a solution can be used as a broad-spectrum preservative for personal care products in cosmetic applications.

Streptococcal and enterococcal endocarditis: time for individualized antibiotherapy?

Recommendations for the treatment of streptococcal and enterococcal endocarditis are based on old efficacy studies, but the starting doses have never been reassessed and are associated with significant adverse events. Based on data from other serious infections, we suggest that maintaining a concentration of β-lactams higher than 4–6 times the responsible bacteria MIC 100% of the time in the heart of the vegetation would be a pertinent therapeutic objective. The data point to a diffusion gradient of β-lactams in the vegetation. Yet, so far as is known, the ratio of antibiotic concentration at steady state between plasma and vegetation cannot be completely determined. Answering this crucial question would make it possible for each patient to have a targeted β-lactam plasma concentration, according to the MIC for the responsible bacteria. This would lead the way to personalized antibiotherapy and allow a safe switch to oral medication.