Comparison of Immuno-PET of CD138 and PET imaging with 64CuCl2 and 18F-FDG in a preclinical syngeneic model of multiple myeloma.
ABSTRACT: Although recent data from the literature suggest that PET imaging with -Fluorodeoxyglucose (18F-FDG) is a promising technique in multiple myeloma (MM), the development of other radiopharmaceuticals seems relevant. CD138 is currently used as a standard marker in many laboratories for the identification and purification of myeloma cells, and could be used in phenotype tumor imaging. In this study, we evaluated a 64Cu-labeled anti-CD138 murine antibody (64Cu-TE2A-9E7.4) and a metabolic tracer (64CuCl2) for PET imaging in a MM syngeneic mouse model.64Cu-TE2A-9E7.4 antibody and 64CuCl2 were evaluated via PET imaging and biodistribution studies in C57BL / KaLwRij mice bearing either 5T33-MM subcutaneous tumors or bone lesions. These results were compared to 18F-FDG-PET imaging. Autoradiography and histology of representative tumors were secondly conducted. In biodistribution and PET studies, 64Cu-TE2A-9E7.4 displayed good tumor uptake of subcutaneous and intra-medullary lesions, greater than that demonstrated with 18F-FDG-PET. In control experiments, only low-level, non-specific uptake of 64Cu-labeled isotype IgG was observed in tumors. Similarly, low activity concentrations of 64CuCl2 were accumulated in MM lesions. Histopathologic analysis of the immuno-PET-positive lesions revealed the presence of plasma cell infiltrates within the bone marrow.64Cu-labeled anti-CD138 antibody can detect subcutaneous MM tumors and bone marrow lesions with high sensitivity, outperforming 18F-FDG-PET and 64CuCl2 in this preclinical model. These data support 64Cu-anti-CD138 antibody as a specific and promising new imaging radiopharmaceutical agent in MM.
Project description:Although positron emission tomography (PET) imaging with 18-Fluorodeoxyglucose (18F-FDG) is a promising technique in multiple myeloma (MM), the development of other radiopharmaceuticals seems relevant. CD138 is currently used as a standard marker for the identification of myeloma cells and could be used in phenotype tumor imaging. In this study, we used an anti-CD138 murine antibody (9E7.4) radiolabeled with copper-64 (64Cu) or zirconium-89 (89Zr) and compared them in a syngeneic mouse model to select the optimal tracers for MM PET imaging. Then, 9E7.4 was conjugated to TE2A-benzyl isothiocyanate (TE2A) and desferrioxamine (DFO) chelators for 64Cu and 89Zr labeling, respectively. 64Cu-TE2A-9E7.4 and 89Zr-DFO-9E7.4 antibodies were evaluated by PET imaging and biodistribution studies in C57BL/KaLwRij mice bearing either 5T33-MM subcutaneous tumors or bone lesions and were compared to 18F-FDG-PET imaging. In biodistribution and PET studies, 64Cu-TE2A-9E7.4 and 89Zr-DFO-9E7.4 displayed comparable good tumor uptake of subcutaneous tumors. On the bone lesions, PET imaging with 64Cu-TE2A-9E7.4 and 89Zr-DFO-9E7.4 showed higher uptake than with 18F-FDG-PET. Comparison of both 9E7.4 conjugates revealed higher nonspecific bone uptakes of 89Zr-DFO-9E7.4 than 64Cu-TE2A-9E7.4. Because of free 89Zr's tropism for bone when using 89Zr-anti-CD138, 64Cu-anti-CD138 antibody had the most optimal tumor-to-nontarget tissue ratios for translation into humans as a specific new imaging radiopharmaceutical agent in MM.
Project description:18F-Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is one of the most widely used imaging techniques to detect multiple myeloma (MM). Intracellular FDG uptake depicts in vivo metabolic activity, which can be seen in both malignant and nonmalignant cells, resulting in limited sensitivity and specificity. Our group showed preclinically that tracing MM dissemination using a CD38-directed human antibody, daratumumab, that is radioconjugated with 64Cu via the chelator DOTA (64Cu-daratumumab), led to improved sensitivity and specificity over that of FDG. Here, we report the results of a phase 1 trial designed to (1) assess the safety and feasibility of 64Cu-daratumumab PET/CT and (2) preliminarily evaluate and characterize the ability of 64Cu-daratumumab to accurately detect or exclude MM lesions. A total of 12 daratumumab-naive patients were imaged. Prior to the injection of 15 mCi/5 mg of 64Cu-daratumumab, patients were treated with 0 (n = 3), 10 (n = 3), 45 (n = 3), or 95 mg (n = 3) of unlabeled daratumumab to assess its effect on image quality. No significant adverse events were observed from either unlabeled daratumumab or 64Cu-daratumumab. Of the dose levels tested, 45 mg unlabeled daratumumab was the most optimal in terms of removing background signal without saturating target sites. 64Cu-daratumumab PET/CT provided safe whole-body imaging of MM. A trial comparing the sensitivity and specificity of 64Cu-daratumumab PET/CT with that of FDG PET/CT is planned. This trial was registered at www.clinicaltrials.gov as #NCT03311828.
Project description:BACKGROUND:Despite the significant upgrading in recent years of the role of 18F-FDG PET/CT in multiple myeloma (MM) diagnostics, there is a still unmet need for myeloma-specific radiotracers. 3'-Deoxy-3'-[18F]fluorothymidine (18F-FLT) is the most studied cellular proliferation PET agent, considered a potentially new myeloma functional imaging tracer. The aim of this pilot study was to evaluate 18F-FLT PET/CT in imaging of MM patients, in the context of its combined use with 18F-FDG PET/CT. RESULTS:Eight patients, four suffering from symptomatic MM and four suffering from smoldering MM (SMM), were enrolled in the study. All patients underwent 18F-FDG PET/CT and 18F-FLT PET/CT imaging by means of static (whole body) and dynamic PET/CT of the lower abdomen and pelvis (dPET/CT) in two consecutive days. The evaluation of PET/CT studies was based on qualitative evaluation, semi-quantitative (SUV) calculation, and quantitative analysis based on two-tissue compartment modeling. 18F-FDG PET/CT demonstrated focal, 18F-FDG avid, MM-indicative bone marrow lesions in five patients. In contrary, 18F-FLT PET/CT showed focal, 18F-FLT avid, myeloma-indicative lesions in only two patients. In total, 48 18F-FDG avid, focal, MM-indicative lesions were detected with 18F-FDG PET/CT, while 17 18F-FLT avid, focal, MM-indicative lesions were detected with 18F-FLT PET/CT. The number of myeloma-indicative lesions was significantly higher for 18F-FDG PET/CT than for 18F-FLT PET/CT. A common finding was a mismatch of focally increased 18F-FDG uptake and reduced 18F-FLT uptake (lower than the surrounding bone marrow). Moreover, 18F-FLT PET/CT was characterized by high background activity in the bone marrow compartment, further complicating the evaluation of bone marrow lesions. Semi-quantitative evaluation revealed that both SUVmean and SUVmax were significantly higher for 18F-FLT than for 18F-FDG in both MM lesions and reference tissue. SUV values were higher in MM lesions than in reference bone marrow for both tracers. CONCLUSIONS:Despite the limited number of patients analyzed in this pilot study, the first results of the trial indicate that 18F-FLT does not seem suitable as a single tracer in MM diagnostics. Further studies with a larger patient population are warranted to generalize the herein presented results.
Project description:Epidermal growth factor receptor (EGFR) is overexpressed and considered as a proper molecular target for diagnosis and targeted therapy of esophageal squamous cell carcinoma (ESCC). This study evaluated the usefulness of PET imaging biomarkers with 64Cu-PCTA-cetuximab and 18F-FDG-PET for anti-EGFR immunotherapy in ESCC models. In vivo EGFR status and glucose metabolism by cetuximab treatment were evaluated using 64Cu-PCTA-cetuximab and 18F-FDG-PET, respectively. Therapeutic responses with imaging biomarkers were confirmed by western blot and immunohistochemistry. TE-4 and TE-8 tumors were clearly visualized by 64Cu-PCTA-cetuximab, and EGFR expression on TE-8 tumors showed 2.6-fold higher uptake than TE-4. Tumor volumes were markedly reduced by cetuximab in TE-8 tumor (92.5 ± 5.9%), but TE-4 tumors were refractory to cetuximab treatment. The SUVs in 64Cu-PCTA-cetuximab and 18F-FDG-PET images were statistically significantly reduced by cetuximab treatment in TE-8 but not in TE-4. 64Cu-PCTA-cetuximab and 18F-FDG-PET images were well correlated with EGFR and pAkt levels. 64Cu-PCTA-cetuximab immuno-PET had a potential for determining EGFR level and monitoring therapeutic response by anti-EGFR therapy. 18F-FDG-PET was also attractive for monitoring efficacy of anti-EGFR therapy. In conclusion, PET imaging biomarkers may be useful for selecting patients that express target molecules and for monitoring therapeutic efficacy of EGFR-targeted therapy in ESCC patients.
Project description:Recently, the somatostatin receptor subtype 2 (SSTR2) selective antagonist sst2-ANT was determined to have a high affinity for SSTR2. Additionally, 111In-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-sst2-ANT showed high uptake in an SSTR2-transfected, tumor-bearing mouse model and suggested that radiolabeled SSTR2 antagonists may be superior to agonists for imaging SSTR2-positive tumors. This report describes the synthesis and evaluation of 64Cu-CB-4,11-bis(carboxymethyl)-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane-sst2-ANT (64Cu-CB-TE2A-sst2-ANT) as a PET radiopharmaceutical for the in vivo imaging of SSTR2-positive tumors.Receptor-binding studies were performed to determine the dissociation constant of the radiopharmaceutical 64Cu-CB-TE2A-sst2-ANT using AR42J rat pancreatic tumor cell membranes. The internalization of 64Cu-CB-TE2A-sst2-ANT was compared with that of the 64Cu-labeled agonist 64Cu-CB-TE2A-tyrosine3-octreotate (64Cu-CB-TE2A-Y3-TATE) in AR42J cells. Both radiopharmaceuticals were also compared in vivo through biodistribution studies using healthy rats bearing AR42J tumors, and small-animal PET/CT of 64Cu-CB-TE2A-sst2-ANT was performed.The dissociation constant value for the radiopharmaceutical was determined to be 26 +/- 2.4 nM, and the maximum number of binding sites was 23,000 fmol/mg. 64Cu-CB-TE2A-sst2-ANT showed significantly less internalization than did 64Cu-CB-TE2A-Y3-TATE at time points from 15 min to 4 h. Biodistribution studies revealed that the clearance of 64Cu-CB-TE2A-sst2-ANT from the blood was rapid, whereas the clearance of 64Cu-CB-TE2A-sst2-ANT from the liver and kidneys was more modest at all time points. Tumor-to-blood and tumor-to-muscle ratios were determined to be better for 64Cu-CB-TE2A-sst2-ANT than those for 64Cu-CB-TE2A-Y3-TATE at the later time points, although liver and kidney uptake was significantly higher. Small-animal imaging using 64Cu-CB-TE2A-sst2-ANT revealed excellent tumor-to-background contrast at 4 h after injection, and standardized uptake values remained high even after 24 h.The PET radiopharmaceutical 64Cu-CB-TE2A-sst2-ANT is an attractive agent, worthy of future study as a PET radiopharmaceutical for the imaging of somatostatin receptor-positive tumors.
Project description:As a growing number of patients with multiple myeloma (MM) respond to upfront therapies while eventually relapsing in a time frame that is often unpredictable, attention has increasingly focused on developing novel diagnostic criteria to also account for disease dissemination. Positron emission tomography/computed tomography (PET/CT) is often used as a noninvasive monitoring strategy to assess cancer cell dissemination, but because the uptake of the currently used radiotracer 18fluorodeoxyglucose (18F-FDG) is a function of the metabolic activity of both malignant and nonmalignant cells, the results frequently lack sufficient specificity. Radiolabeled antibodies targeting MM tissue may detect disease irrespective of cell metabolism. Hence, we conjugated the clinically significant CD38-directed human antibody daratumumab (Darzalex [Dara]) to the DOTA chelator and labeled it with the positron-emitting radionuclide copper 64 (64Cu; 64Cu-DOTA-Dara). Here, we show that 64Cu-DOTA-Dara can efficiently bind CD38 on the surface of MM cells and was mainly detected in the bones associated with tumor in a MM murine model. We also show that PET/CT based on 64Cu-DOTA-Dara displays a higher resolution and specificity to detect MM cell dissemination than does 18F-FDG PET/CT and was even more sensitive than were bioluminescence signals. We therefore have supporting evidence for using 64Cu-DOTA-Dara as a novel imaging agent for MM.
Project description:An observational study was set up to assess the feasibility of [18F]FPRGD2 PET/CT for imaging patients with multiple myeloma (MM) and to compare its detection rate with low dose CT alone and combined [18F]NaF/[18F]FDG PET/CT images. Four patients (2 newly diagnosed patients and 2 with relapsed MM) were included and underwent whole-body PET/CT after injection of [18F]FPRGD2. The obtained images were compared with results of low dose CT and already available results of a combined [18F]NaF/[18F]FDG PET/CT. In total, 81 focal lesions (FLs) were detected with PET/CT and an underlying bone destruction or fracture was seen in 72 (89%) or 8 (10%) FLs, respectively. Fewer FLs (54%) were detected by [18F]FPRGD2 PET/CT compared to low dose CT (98%) or [18F]NaF/[18F]FDG PET/CT (70%) and all FLs detected with [18F]FPRGD2 PET were associated with an underlying bone lesion. In one newly diagnosed patient, more [18F]FPRGD2 positive lesions were seen than [18F]NaF/[18F]FDG positive lesions. This study suggests that [18F]FPRGD2 PET/CT might be less useful for the detection of myeloma lesions in patients with advanced disease as all FLs with [18F]FPRGD2 uptake were already detected with CT alone.
Project description:Positron emission tomography and computed tomography imaging (PET/CT) is an increasingly valuable tool for diagnosing tuberculosis (TB). The glucose analog [18F]fluoro-2-deoxy-2-d-glucose ([18F]-FDG) is commonly used in PET/CT that is retained by metabolically active inflammatory cells in granulomas, but lacks specificity for particular cell types. A PET probe that could identify recruitment and differentiation of different cell populations in granulomas would be a useful research tool and could improve TB diagnosis and treatment. We used the Mycobacterium-antigen murine inflammation model and macaques with TB to identify [64Cu]-labeled CB-TE1A1P-PEG4-LLP2A ([64Cu]-LLP2A), a high affinity peptidomimetic ligand for very late Ag-4 (VLA-4; also called integrin ?4?1) binding cells in granulomas, and compared [64Cu]-LLP2A with [18F]-FDG over the course of infection. We found that [64Cu]-LLP2A retention was driven by macrophages and T cells, with less contribution from neutrophils and B cells. In macaques, granulomas had higher [64Cu]-LLP2A uptake than uninfected tissues, and immunohistochemical analysis of granulomas with known [64Cu]-LLP2A uptake identified significant correlations between LLP2A signal and macrophage and T cell numbers. The same cells coexpressed integrin ?4 and ?1, further supporting that macrophages and T cells drive [64Cu]-LLP2A avidity in granulomas. Over the course of infection, granulomas and thoracic lymph nodes experienced dynamic changes in affinity for both probes, suggesting metabolic changes and cell differentiation or recruitment occurs throughout granuloma development. These results indicate [64Cu]-LLP2A is a PET probe for VLA-4, which when used in conjunction with [18F]-FDG, may be a useful tool for understanding granuloma biology in TB.
Project description:Due to the high mortality of lung cancer, there is a critical need to develop diagnostic procedures enabling early detection of the disease while at a curable stage. Targeted molecular imaging builds on the positive attributes of positron emission tomography/computed tomography (PET/CT) to allow for a noninvasive detection and characterization of smaller lung nodules, thus increasing the chances of positive treatment outcome. In this study, we investigate the ability to characterize lung tumors that spontaneously arise in a transgenic mouse model. The tumors are first identified with small animal CT followed by characterization with the use of small animal PET with a novel 64Cu-1,4,7,10-tetra-azacylododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-knottin peptide that targets integrins upregulated during angiogenesis on the tumor associated neovasculature. The imaging results obtained with the knottin peptide are compared with standard 18F-fluorodeoxyglucose (FDG) PET small animal imaging. Lung nodules as small as 3 mm in diameter were successfully identified in the transgenic mice by small animal CT, and both 64Cu-DOTA-knottin 2.5F and FDG were able to differentiate lung nodules from the surrounding tissues. Uptake and retention of the 64Cu-DOTA-knottin 2.5F tracer in the lung tumors combined with a low background in the thorax resulted in a statistically higher tumor to background (normal lung) ratio compared with FDG (6.01±0.61 versus 4.36±0.68; P<0.05). Ex vivo biodistribution showed 64Cu-DOTA-knottin 2.5F to have a fast renal clearance combined with low nonspecific accumulation in the thorax. Collectively, these results show 64Cu-DOTA-knottin 2.5F to be a promising candidate for clinical translation for earlier detection and improved characterization of lung cancer.
Project description:The incidence and importance of bone marrow involvement and/or early bone lesions in multiple myeloma (MM) precursor diseases is largely unknown. This study prospectively compared the sensitivity of several imaging modalities in monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM) and MM. Thirty patients (10 each with MGUS, SMM and MM) were evaluated with skeletal survey, [18F]FDG-PET/CT, [18F]NaF-PET/CT and morphologic dynamic contrast enhanced (DCE)-MRI. An additional 16 SMM patients had skeletal surveys and FDG-PET/CT. Among MGUS patients, DCE-MRI found only one focal marrow abnormality; other evaluations were negative. Among 26 SMM patients, five (19%) were re-classified as MM based on lytic bone lesions on CT and six had unifocal or diffuse marrow abnormality. Among MM, marrow abnormalities were observed on FDG-PET/CT in 8/10 patients and on DCE-MRI in nine evaluable patients. Abnormal NaF uptake was observed only in MM patients with lytic lesions on CT, providing no additional clinical information.