Preclinical Development of Near-Infrared-Labeled CD38-Targeted Daratumumab for Optical Imaging of CD38 in Multiple Myeloma

Abstract

Purpose: Cluster of differentiation 38 (CD38) is a promising therapeutic target in multiple myeloma (MM) patients and has resulted in the development of several CD38 immunotherapies. Current methods to evaluate CD38 expression in the preclinical setting include ex vivo flow cytometry and immunohistochemistry, which can be cumbersome and do not give whole-body information. In vivo imaging technologies such as positron emission tomography rely on decay of radioisotopes, limiting the number of molecular interactions observed at any given time point. Here, we demonstrate the use of near-infrared (NIR) fluorescence imaging for spatiotemporal monitoring of CD38 expression in preclinical MM using the anti-CD38 daratumumab (DARA) conjugated to the NIR fluorophore IRDye800CW (DARA-IRDye800).Procedures: Stability studies with human serum and binding assays with human myeloma cells were performed with DARA-IRDye800. Immunocompromised mice with intra-and extramedullary tumors (n = 5/group) were administered with DARA-IRDye800 for in vivo imaging up to 7 days after injection. Ex vivo biodistribution and flow cytometry studies were performed to validate in vivo imaging results. A separate therapy study was performed in mice with intramedullary tumors that were treated and not treated with DARA at a therapeutic dose (n = 7/group). DARA-IRDye800 was administered for subsequent in vivo and ex vivo imaging in both cohorts of mice.Results: DARA-IRDye800 maintained stability and had high affinity for CD38 (K D = 3.5 ± 0.05 nM). DARA-IRDye800 demonstrated a 5-and 18-fold increase in contrast in tumor-bearing regions of mice with extra-and intramedullary MM. Finally, mice treated with therapeutic

CD38-specific nanobodies allow in vivo imaging of multiple myeloma under daratumumab therapy

“…Previous studies demonstrated the feasibility of fluorophore- or radionuclide-labeled daratumumab for in vivo imaging purposes of CD38-expressing myeloma cells ( 19 , 20 , 41 ). However, targeting the same epitope as daratumumab is only effective in daratumumab-naive patients.…”

“…Instead of using a conventional monoclonal antibody, we used nanobody JK36 AF680 , recognizing a distinct, non-overlapping epitope of CD38 for demonstrating the feasibility of specific imaging of daratumumab-pretreated CD38-expressing tumors. Key advantages of using nanobodies over conventional antibodies for in vivo diagnostic purposes include greater ease of production ( 42 ) as well as more favorable imaging kinetics: nanobodies allow for excellent tumor-to-background ratios as early as 6 hours post-injection and for same-day in vivo imaging ( 33 , 41 ), owing to the rapid elimination of excess unbound nanobodies by renal filtration. Furthermore, the risk of allergic infusion reactions is reduced when using nanobodies as opposed to conventional antibodies, owing to their low immunogenicity ( 43 ).…”

Tissue biodistribution and tumor targeting of near-infrared labelled anti-CD38 antibody-drug conjugate in preclinical multiple myeloma

“…Our in vivo imaging results showed that both immunoconjugates had high specificity to GFP + tumor lesions in both mouse models. We, and others, have previously demonstrated that IV injection of human myeloma cells results in diffuse tumor growth in variable regions of bone marrow in mice compared to the localized tumor burden observed in MM.1S SQ mice [ 29 , 30 ]. MM is a plasma cell disorder that causes significant skeletal morbidity within the bone marrow niche.…”

Recent developments on the application of molecular probes in multiple myeloma: Beyond [18F]FDG

“…Preclinical evaluation of DARA-IRDye800, in which DARA conjugated to the NIR fluorophore IRDye800CW, revealed a significant (~10×) reduction in vivo in fluorescence intensity for the treated group (listed in Table 3). (Cho et al, 2021) 2.3.5 B cell maturation antigen and signaling lymphocyte activation molecule 7 B cell maturation antigen (BCMA) is a member of the tumor necrosis factor receptor superfamily that is found almost exclusively on mature B cells. Its expression level increases significantly in MM cells, and its expression level is positively correlated with MM progression (Shah et al, 2020).…”