Navidea Biopharmaceuticals Announces Publication of Study Investigating Tc99m Tilmanocept Imaging of Arterial Inflammation in People Living with HIV

DUBLIN, Ohio–(BUSINESS WIRE)–Navidea Biopharmaceuticals, Inc. (NYSE American: NAVB) (“Navidea” or the “Company”), a company specializing in the development of precision immunodiagnostic agents and immunotherapies, today announced the publication of a manuscript titled “Increased Macrophage Specific Arterial Inflammation Uniquely Relates to Noncalcified Plaque and Specific Immune Activation Pathways in People Living with HIV: A Targeted Molecular Imaging Approach,” based on work performed at Massachusetts General Hospital (“MGH”) and Harvard Medical School, Boston MA, and sponsored by the company. The Journal of Infectious Diseases (PMID: 35856671), was led by lead researcher Steven Grinspoon, MD, head of the Metabolism Unit at Mass General Hospital and professor of medicine at Harvard Medical School.

Persistent immune activation and specific arterial downstream macrophage infiltration are thought to contribute to the increased risk of atherosclerotic cardiovascular disease (plaque) in people living with HIV on antiretroviral therapy (“ART”). In this study, tilmanocept Tc99m imaging was applied to study macrophage-specific arterial inflammation in participants with versus matched participants without HIV. The hypothesis was that people living with HIV would show higher levels of aortic arterial inflammation in relation to atherosclerotic plaque and immune activation.

Results showed that HIV-positive patients on antiretroviral therapy (N=20) had significantly higher macrophage-specific arterial inflammation demonstrated by tilmanocept Tc99m than risk-matched non-HIV-positive people (N=10). Total, non-calcified, and calcified aortic plaque volume calculated from CT scans did not differ significantly between groups. Macrophage-specific arterial inflammation linked to non-calcified plaque in HIV patients (not HIV-free participants) and further linked to levels of specific inflammatory markers. Aortic uptake of Tc99m-tilmanocept was significantly higher for different uptake thresholds in seropositive participants (P = 0.03) and demonstrated a stronger relationship between arterial inflammation and volume of non-calcified plaque (P = 0.0001 for the interaction between HIV status and plaque volume) but non-calcified plaque volume (P = 0.83 for the interaction). Among people living with HIV (not among participants without HIV), the volume of non-calcified aortic plaque was directly related to aortic uptake of Tc99m-tilmanocept at different uptake thresholds.

Macrophage-specific arterial inflammation, quantified using a new molecular imaging approach, was higher in HIV-positive patients on ART than in matched participants with similar atherosclerotic cardiovascular risk without HIV. Arterial inflammation related to non-calcified plaque volume only in HIV-infected patients. Cellular biomarkers of inflammation are also linked to macrophage-specific arterial inflammation. These key immune pathways may contribute to an increased risk of cardiovascular disease in people living with HIV and are therefore relevant for identifying new therapies.

These data suggest that increased arterial inflammation specific to non-calcified plaque macrophages may be a mechanism for increased cardiovascular risk in people living with HIV. The use of Tc99m tilmanocept imaging may help identify future targets for new immunomodulatory therapies to reduce the risk of atherosclerotic cardiovascular disease in people living with HIV on ART.

Dr. Michael Rosol, Navidea’s Chief Medical Officer, said: “We are delighted to have helped sponsor this important work with Dr. Grinspoon at MGH. This is another research collaboration we have had with top researchers at leading institutions. Dr. Rosol continued, “Today’s announcement illustrates the broad reach of our tilmanocept platform. Developing applications of tilmanocept Tc99m as a biomarker in people living with HIV could have far-reaching implications for monitoring patient treatment and making decisions about therapeutic benefit.

Dr Grinspoon said: “This study provides another key piece of evidence for increased arterial inflammation in relation to monocytes and activation and major pathways of innate immune activation in people living with HIV. . Tilmanocept may be useful for evaluating new immunomodulatory strategies to reduce inflammation and improve cardiovascular disease risk in PWH.

About Navidea

Navidea Biopharmaceuticals, Inc. (NYSE American: NAVB) is a biopharmaceutical company specializing in the development of precision immunodiagnostic agents and immunotherapies. Navidea is developing several precision-targeted products based on its Manocept platform to improve patient care by identifying sites and pathways of disease and enabling better diagnostic accuracy, clinical decision-making and targeted treatment. Navidea’s Manocept platform relies on the ability to specifically target the CD206 mannose receptor expressed on activated macrophages. The Manocept platform serves as the molecular backbone of tilmanocept Tc99m, the first product developed and marketed by Navidea based on the platform. Navidea’s strategy is to deliver superior growth and shareholder return by bringing new products to market and advancing the company’s pipeline through global partnership and marketing efforts. For more information, please visit www.navidea.com.

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