In vivo quantitative assessment of therapeutic response to bortezomib therapy in disseminated animal models of multiple myeloma with [18F]FDG and [64Cu]Cu-LLP2A PET

Anchal Ghai; Nikki Fettig; Francesca Fontana; John DiPersio; Mike Rettig; Julie O Neal; Samuel Achilefu; Kooresh I Shoghi; Monica Shokeen

doi:10.1186/s13550-021-00840-4

In vivo quantitative assessment of therapeutic response to bortezomib therapy in disseminated animal models of multiple myeloma with [¹⁸F]FDG and [⁶⁴Cu]Cu-LLP2A PET

EJNMMI Res. 2021 Sep 29;11(1):97. doi: 10.1186/s13550-021-00840-4.

Authors

Anchal Ghai¹, Nikki Fettig¹, Francesca Fontana², John DiPersio³, Mike Rettig³, Julie O Neal³, Samuel Achilefu^{1

4

5}, Kooresh I Shoghi¹, Monica Shokeen^{6

7}

Affiliations

¹ Department of Radiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, 4515 McKinley Avenue, 2nd floor, St. Louis, MO, 63110, USA.
² Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA.
³ Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
⁴ Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA.
⁵ Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA.
⁶ Department of Radiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, 4515 McKinley Avenue, 2nd floor, St. Louis, MO, 63110, USA. shokeenm@wustl.edu.
⁷ Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA. shokeenm@wustl.edu.

Abstract

Background: Multiple myeloma (MM) is a disease of cancerous plasma cells in the bone marrow. Imaging-based timely determination of therapeutic response is critical for improving outcomes in MM patients. Very late antigen-4 (VLA4, CD49d/CD29) is overexpressed in MM cells. Here, we evaluated [¹⁸F]FDG and VLA4 targeted [⁶⁴Cu]Cu-LLP2A for quantitative PET imaging in disseminated MM models of variable VLA4 expression, following bortezomib therapy.

Methods: In vitro and ex vivo VLA4 expression was evaluated by flow cytometry. Human MM cells, MM.1S-CG and U266-CG (C: luciferase and G: green fluorescent protein), were injected intravenously in NOD-SCID gamma mice. Tumor progression was monitored by bioluminescence imaging (BLI). Treatment group received bortezomib (1 mg/kg, twice/week) intraperitoneally. All cohorts (treated, untreated and no tumor) were longitudinally imaged with [¹⁸F]FDG (7.4-8.0 MBq) and [⁶⁴Cu]Cu-LLP2A (2-3 MBq; Molar Activity: 44.14 ± 1.40 MBq/nmol) PET, respectively.

Results: Flow cytometry confirmed high expression of CD49d in U266 cells (> 99%) and moderate expression in MM.1S cells (~ 52%). BLI showed decrease in total body flux in treated mice. In MM.1S-CG untreated versus treated mice, [⁶⁴Cu]Cu-LLP2A localized with a significantly higher SUV_mean in spine (0.58 versus 0.31, p < 0.01) and femur (0.72 versus 0.39, p < 0.05) at week 4 post-tumor inoculation. There was a four-fold higher uptake of [⁶⁴Cu]Cu-LLP2A (SUV_mean) in untreated U266-CG mice compared to treated mice at 3 weeks post-treatment. Compared to [⁶⁴Cu]Cu-LLP2A, [¹⁸F]FDG PET detected treatment-related changes at later time points.

Conclusion: [⁶⁴Cu]Cu-LLP2A is a promising tracer for timely in vivo assessment of therapeutic response in disseminated models of MM.

Keywords: Bortezomib (proteasome inhibitor) therapy; Multiple myeloma (MM); Therapy response; Very late antigen-4 (VLA4); [18F]FDG; [64Cu]Cu-LLP2A.

Abstract

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