American Association for Cancer Research
10780432ccr191655-sup-222659_2_supp_5966985_q2mn32.png (1.28 MB)

Figure S3 from Efficacy of Affibody-Based Ultrasound Molecular Imaging of Vascular B7-H3 for Breast Cancer Detection

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posted on 2023-03-31, 21:22 authored by Rakesh Bam, Patrick S. Lown, Lawrence A. Stern, Karina Sharma, Katheryne E. Wilson, Gregory R. Bean, Amelie M. Lutz, Ramasamy Paulmurugan, Benjamin J. Hackel, Jeremy Dahl, Lotfi Abou-Elkacem

ABYB7-H3 positively stains B7-H3 expressed in the tissue sections from human breast cancer patients.





Human B7-H3 (hB7-H3) is a promising molecular imaging target differentially expressed on the neovasculature of breast cancer and has been validated for preclinical ultrasound (US) imaging with anti–B7-H3-antibody-functionalized microbubbles (MB). However, smaller ligands such as affibodies (ABY) are more suitable for the design of clinical-grade targeted MB. Binding of ABYB7-H3 was confirmed with soluble and cell-surface B7-H3 by flow cytometry. MB were functionalized with ABYB7-H3 or anti–B7-H3-antibody (AbB7-H3). Control and targeted MB were tested for binding to hB7-H3–expressing cells (MS1hB7-H3) under shear stress conditions. US imaging was performed with MBABY-B7-H3 in an orthotopic mouse model of human MDA-MB-231 coimplanted with MS1hB7-H3 or control MS1WT cells and a transgenic mouse model of breast cancer development. ABYB7-H3 specifically binds to MS1hB7-H3 and murine-B7-H3–expressing monocytes. MBABY-B7-H3 (8.5 ± 1.4 MB/cell) and MBAb-B7-H3 (9.8 ± 1.3 MB/cell) showed significantly higher (P < 0.0001) binding to the MS1hB7-H3 cells compared with control MBNon-targeted (0.5 ± 0.1 MB/cell) under shear stress conditions. In vivo, MBABY-B7-H3 produced significantly higher (P < 0.04) imaging signal in orthotopic tumors coengrafted with MS1hB7-H3 (8.4 ± 3.3 a.u.) compared with tumors with MS1WT cells (1.4 ± 1.0 a.u.). In the transgenic mouse tumors, MBABY-B7-H3 (9.6 ± 2.0 a.u.) produced higher (P < 0.0002) imaging signal compared with MBNon-targeted (1.3 ± 0.3 a.u.), whereas MBABY-B7-H3 signal in normal mammary glands and tumors with B7-H3 blocking significantly reduced (P < 0.02) imaging signal. MBABY-B7-H3 enhances B7-H3 molecular signal in breast tumors, improving cancer detection, while offering the advantages of a small size ligand and easier production for clinical imaging.