CD38 as a PET Imaging Target in Lung Cancer

Abstract

Daratumumab (Darzalex, Janssen Biotech) is a clinically approved antibody targeting CD38 for the treatment of multiple myeloma. However, CD38 is also expressed by other cancer cell types, including lung cancer, where its expression or absence may offer prognostic value. We therefore developed a PET tracer based upon daratumumab for tracking CD38 expression, utilizing murine models of non-small cell lung cancer to verify its specificity. Daratumumab was prepared for radiolabeling with 89Zr (t1/2 = 78.4 h) through conjugation with desferrioxamine (Df). Western blot, flow cytometry, and saturation binding assays were utilized to characterize CD38 expression and binding of daratumumab to three non-small cell lung cancer cell lines: A549, H460, and H358. Murine xenograft models of the cell lines were also generated for further in vivo studies. Longitudinal PET imaging was performed following injection of 89Zr-Df–daratumumab out to 120 h postinjection, and nonspecific uptake was also evaluated through the injection of a radiolabeled control IgG antibody in A549 mice, 89Zr-Df–IgG. Ex vivo biodistribution and histological analyses were also performed after the terminal imaging time point at 120 h postinjection. Through cellular studies, A549 cells were found to express higher levels of CD38 than the H460 or H358 cell lines. PET imaging and ex vivo biodistribution studies verified in vitro trends, with A549 tumor uptake peaking at 8.1 ± 1.2%ID/g at 120 h postinjection according to PET analysis, and H460 and H358 at lower levels at the same time point (6.7 ± 0.7%ID/g and 5.1 ± 0.4%ID/g, respectively; n = 3 or 4). Injection of a nonspecific radiolabeled IgG into A549 tumor-bearing mice also demonstrated lower tracer uptake of 4.4 ± 1.3%ID/g at 120 h. Immunofluorescent staining of tumor tissues showed higher staining levels present in A549 tissues over H460 and H358. Thus, 89Zr-Df–daratumumab is able to image CD38-expressing tissues in vivo using PET, as verified through the exploration of non-small cell lung cancer models in this study. This agent therefore holds potential to image CD38 in other malignancies and aid in patient stratification and elucidation of the biodistribution of CD38.

ImmunoPET imaging of CD38 in murine lymphoma models using 89Zr-labeled daratumumab

“…The preparation of 89 Zr (t 1/2 = 78.4 h) radiolabeled daratumumab was performed through conjugation with SCN-Bn-deferoxamine (Df), as described in previous protocols [14, 15]. Briefly, 4 mg of daratumumab was added to 500 µL of PBS and adjusted to a pH of 8.5 – 9.0 with Na 2 CO 3 (0.1 M), then Df dissolved in dimethyl sulfoxide was added at a 1:10 molar ratio.…”

“…In our previous study, 89 Zr-labeled daratumumab was developed as a PET probe to visualize CD38 expression in lung cancer models [14]. However, the relatively low tumor uptake (highest at 8.1 ± 1.2 %ID/g) limited its potential for lung tumor imaging.…”

Poly(ADP-Ribose) Polymerases in Host-Pathogen Interactions, Inflammation, and Immunity

“…The antibody exhibited high efficacy in an animal model of multiple myeloma (434). CD38 has also been developed as a target for positron emission tomography (PET) imaging using daratumumab antibody (435,436). Other antibodies, such as MOR202, a human antibody, and isatuximab, a humanized antibody, are in various stages of clinical trials (437,438).…”

Computational Gene Expression Profiling in Non-Small Cell Lung Cancer Reveals Network-Based Immune Signatures Associated With Smoking and Overall Survival

“…Six of them (CD27, CD38, GUSBP11, IGKC, IGLL3P, and IGHD) presented similar results in validation microarray. Among them, CD38 was found being up-regulated in life-long smokers [32] and highly expressed in lung cancers [33]. However, the remaining genes had few reports about connecting their expression with smoking.…”