Imaging angiogenesis in patients with head and neck squamous cell carcinomas by [68Ga]Ga-DOTA-E-[c(RGDfK)]2 PET/CT

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Bevacizumab reduces tumor targeting of antiepidermal growth factor and anti-insulin-like growth factor 1 receptor antibodies

Bevacizumab (antivascular endothelial growth factor [anti-VEGF]) and cetuximab (antiepidermal growth factor receptor [anti-EGFR]) are approved antibodies for treatment of cancer. However, in advanced colorectal cancer, the combination fails to improve survival. As the reason for the lack of activity is unknown, our study aims to determine the effect of bevacizumab on targeting of anti-EGFR and insulin-like growth factor 1 receptor (IGF-1R) antibodies in tumors with single-photon emission computed tomography (SPECT)/CT imaging. Mice with subcutaneous EGFR and IGF-1R-expressing SUM149 xenografts received a single dose of bevacizumab (10 mg/kg) or saline. After 4 days, mice were injected with radiolabeled cetuximab or R1507, an anti-IGF-1R antibody. A control group received a radiolabeled irrelevant IgG (hLL2). Three days later, SPECT/CT images were acquired and mice were dissected to determine the concentration of antibodies in the tissues. Tumors were analyzed immunohistochemically to determine vascular density (CD34), VEGF, EGFR and IGF-1R expression. SPECT/CT imaging revealed that bevacizumab treatment significantly reduced tumor targeting of radiolabeled cetuximab by 40% from 33.1 +/- 1.1 %ID/g to 19.8 +/- 5.7 %ID/g (p=0.009) for untreated and bevacizumab-treated tumors, respectively. A similar effect was found for 111In-R1507: tumor targeting of R1507 decreased by 35%. No significant differences in tumor uptake were observed in mice that received an irrelevant IgG. Uptake in normal organs was not altered by bevacizumab. Immunohistochemical analysis showed that vascular density decreased with 43%, whereas EGFR and IGF-1R expression was unaltered. In conclusion, bevacizumab treatment significantly reduces tumor targeting of anti-EGFR and anti-IGF-1R antibodies. This emphasizes the importance of timing and sequencing of bevacizumab in combination with other antibodie

Targeted Alpha Radionuclide Therapy of Prostate Cancer Using a Small Molecule Inhibitor of Prostate-specific Membrane Antigen (PSMA)

Objectives: PSMA is a well-recognized target for imaging and therapy of prostate cancer (PCa), as it is expressed in nearly all PCa lesions. Radiolabeled PSMA inhibitors localize rapidly to tumor lesions, including soft-tissue and bone metastases, but also show high uptake in kidneys and salivary glands. The aim of the present study was to evaluate the potential of 213Bi-PSMA I&T a DOTA-chelated urea-based PSMA inhibitor, as therapeutic agent in PSMA-expressing tumor cells in vitro and in vivo. Materials and Methods: PSMA I&T was labeled with 111In for biodistribution studies and with 213Bi for therapeutic studies. The tumor targeting of 111In-PSMA I&T was evaluated in mice with subcutaneous LNCaP tumors and PSMA-transfected LS174T tumors. Biodistribution was determined 2 h after injection of 0.1, 0.3, 1, or 10 nmol of 111In-PSMA I&T. Blocking of PSMA-specific binding to kidneys was investigated by co-injecting 2-(Phosphonomethyl)pentane-1,5-dioic acid (PMPA). Next, the therapeutic efficacy of 213Bi-PSMA I&T was tested in vitro in LNCaP cells and in vivo in mice with LNCaP xenografts. Cells were incubated for 20 min with 213Bi-PSMA I&T, 213Bi-DTPA, or medium, and fixed at 1, 2, 4, 24, and 48 h after treatment. Mice were injected with 213Bi-PSMA I&T (0.2 nmol, 5 MBq) and biodistribution was determined at 1 h after injection. In addition, tumor and kidneys were dissected 1 h and 24 h after injection. Fixed cells and tissues were stained with an anti-53BP1 antibody, an anti-GEMININ antibody and a TUNEL detection kit. Results: 111In-PSMA I&T uptake in LNCaP and LS174T-PSMA tumors, kidneys, spleen, lung and salivary glands was dependent on amount of injected peptide. Optimal doses for tumor targeting were between 0.1 and 0.3 nmol. Co-injection of 10 nmol PMPA resulted in a 2.5-fold decrease in renal uptake, and a 1.2-fold decrease in tumor uptake. Treatment of LNCaP cells with 213Bi-PSMA I&T caused a decrease in cellular proliferation, accumulation of DNA double-strand breaks, and induction of apoptosis. The biodistribution of 213Bi-PSMA I&T and 111In-PSMA I&T were similar. 213Bi-PSMA I&T induced DNA-double strand breaks in LNCaP tumors, from which a significant amount was not repaired at 24 h after injection. Conclusion: PSMA I&T is a promising targeting agent for radionuclide therapy of PCa. In this study we showed that renal accumulation of this tracer can be efficiently reduced by co-injection of PMPA, while tumor uptake was preserved. Our preliminary results reveal a good targeting and therapeutic effect of 213Bi-PSMA I&T in LNCaP cells in vitro and in vivo.JRC.E.5-Nuclear chemistr

Multiscale imaging of therapeutic anti-PD-L1 antibody localization using molecularly defined imaging agents

BACKGROUND: While immune checkpoint inhibitors such as anti-PD-L1 antibodies have revolutionized cancer treatment, only subgroups of patients show durable responses. Insight in the relation between clinical response, PD-L1 expression and intratumoral localization of PD-L1 therapeutics could improve patient stratification. Therefore, we present the modular synthesis of multimodal antibody-based imaging tools for multiscale imaging of PD-L1 to study intratumoral distribution of PD-L1 therapeutics. RESULTS: To introduce imaging modalities, a peptide containing a near-infrared dye (sulfo-Cy5), a chelator (DTPA), an azide, and a sortase-recognition motif was synthesized. This peptide and a non-fluorescent intermediate were used for site-specific functionalization of c-terminally sortaggable mouse IgG1 (mIgG1) and Fab anti-PD-L1. To increase the half-life of the Fab fragment, a 20 kDa PEG chain was attached via strain-promoted azide-alkyne cycloaddition (SPAAC). Biodistribution and imaging studies were performed with (111)In-labeled constructs in 4T1 tumor-bearing mice. Comparing our site-specific antibody-conjugates with randomly conjugated antibodies, we found that antibody clone, isotype and method of DTPA conjugation did not change tumor uptake. Furthermore, addition of sulfo-Cy5 did not affect the biodistribution. PEGylated Fab fragment displayed a significantly longer half-life compared to unPEGylated Fab and demonstrated the highest overall tumor uptake of all constructs. PD-L1 in tumors was clearly visualized by SPECT/CT, as well as whole body fluorescence imaging. Immunohistochemistry staining of tumor sections demonstrated that PD-L1 co-localized with the fluorescent and autoradiographic signal. Intratumoral localization of the imaging agent could be determined with cellular resolution using fluorescent microscopy. CONCLUSIONS: A set of molecularly defined multimodal antibody-based PD-L1 imaging agents were synthesized and validated for multiscale monitoring of PD-L1 expression and localization. Our modular approach for site-specific functionalization could easily be adapted to other targets. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12951-022-01272-5

A Clinical Feasibility Study To Image Angiogenesis in Patients With Arteriovenous Malformations Using Ga-RGD PET/CT.

Arteriovenous malformations (AVMs) have an inherent capacity to form new blood vessels, resulting in excessive lesion growth, and this process is further triggered by the release of angiogenic factors. 68Ga-labeled arginine-glycine-aspartate tripeptide sequence (RGD) PET/CT imaging may provide insight into the angiogenic status and treatment response of AVMs. This clinical feasibility study was performed to demonstrate that 68Ga-RGD PET/CT imaging can be used to quantitatively assess angiogenesis in peripheral AVMs. METHODS: Ten patients with a peripheral AVM (mean age, 40 y; 4 men and 6 women) and scheduled for endovascular embolization treatment were prospectively included. All patients underwent 68Ga-RGD PET/CT imaging 60 min after injection (mean dose, 207 ± 5 MBq). Uptake in the AVM, blood pool, and muscle was quantified as SUVmax and SUVpeak, and a descriptive analysis of the PET/CT images was performed. Furthermore, immunohistochemical analysis was performed on surgical biopsy sections of peripheral AVMs to investigate the expression pattern of integrin αvβ3 RESULTS: 68Ga-RGD PET/CT imaging showed enhanced uptake in all AVM lesions (mean SUVmax, 3.0 ± 1.1; mean SUVpeak, 2.2 ± 0.9). Lesion-to-blood and lesion-to-muscle ratios were 3.5 ± 2.2 and 4.6 ± 2.8, respectively. Uptake in blood and muscle was significantly higher in AVMs than in background tissue (P = 0.0006 and P = 0.0014, respectively). Initial observations included uptake in multifocal AVM lesions and enhanced uptake in intraosseous components in those AVM cases affecting bone integrity. Immunohistochemical analysis revealed cytoplasmatic and membranous integrin αvβ3 expression in the endothelial cells of AVMs. CONCLUSION: This feasibility study showed increased uptake in AVMs with angiogenic activity, compared with surrounding tissue without angiogenic activity, suggesting that 68Ga-RGD PET/CT imaging can be used as a tool to quantitatively determine angiogenesis in AVMs. Further studies will be conducted to explore the potential of 68Ga-RGD PET/CT imaging for guiding current treatment decisions and for assessing response to antiangiogenic treatment

Cetuximab Reduces the Accumulation of Radiolabeled Bevacizumab in Cancer Xenografts without Decreasing VEGF Expression

Bevacizumab and cetuximab are approved for the treatment of cancer. However, in advanced colorectal cancer, addition of cetuximab to chemotherapy with bevacizumab did not improve survival. The reason for the lack of activity remains unclear. The aim of this study was to determine the effect of cetuximab on VEGF expression and targeting of bevacizumab to the tumor. Mice with subcutaneous SUM149 or WiDr xenografts were treated with cetuximab, bevacizumab, or a combination of the two. Before the start of cetuximab treatment and after 7 and 21 days of treatment, the uptake of radiolabeled bevacizumab in the tumor was measured by immunoSPECT/CT. Tumor growth of SUM149 xenografts was significantly inhibited by cetuximab, bevacizumab, or their combination, whereas growth of WiDr xenografts was not affected. Cetuximab caused a significant reduction of bevacizumab uptake in SUM149 xenografts, whereas tumor-to-blood ratios in mice with WiDr xenografts did not change. Biodistribution studies with an irrelevant antibody in the SUM149 model also showed significantly reduced tumor-to-blood ratios. Cetuximab treatment did not decrease VEGF expression. Without decreasing VEGF levels, cetuximab reduces tumor targeting of bevacizumab. This could, at least partly, explain why the combination of bevacizumab and cetuximab does not result in improved therapeutic efficacy

Kaplan-Meier survival curves.

<p>Kaplan-Meier survival curve estimates of overall survival of chemotherapy (<b>A</b>) or endocrine therapy (<b>B</b>) treated patients with a tumor showing a downregulation, no change or an upregulation in IGF-1R expression after neoadjuvant treatment (p = 0.060 and p = 0.069, respectively).</p

Kaplan-Meier survival curves.

<p>Kaplan-Meier survival curve estimates showing the effect of baseline IGF-1R expression (left) and changes in IGF-1R expression (right) on overall survival in the total population (<b>A</b>), and subgroup analysis in patients with non-metastatic disease (<b>B</b>) and metastatic disease (<b>C</b>).</p

Patient (N = 62) and tumor (N = 63) characteristics.

<p>Patient (N = 62) and tumor (N = 63) characteristics.</p

Examples of IGF-1R immunostaining of breast tumors.

<p>Scoring of IGF-1R membrane expression is depicted in the lower left corner. Magnification 400X, DAB staining.</p