SPECT/CT imaging of chemotherapy-induced tumor apoptosis using 99mTc-labeled dendrimer-entrapped gold nanoparticles

Non-invasive imaging of apoptosis in tumors induced by chemotherapy is of great value in the evaluation of therapeutic efficiency. In this study, we report the synthesis, characterization, and utilization of radionuclide technetium-99m (99mTc)-labeled dendrimer-entrapped gold nanoparticles (Au DENPs) for targeted SPECT/CT imaging of chemotherapy-induced tumor apoptosis. Generation five poly(amidoamine) (PAMAM) dendrimers (G5.NH2) were sequentially conjugated with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), polyethylene glycol (PEG) modified duramycin, PEG monomethyl ether, and fluorescein isothiocyanate (FI) to form the multifunctional dendrimers, which were then utilized as templates to entrap gold nanoparticles. Followed by acetylation of the remaining dendrimer surface amines and radiolabeling of 99mTc, the SPECT/CT dual mode nanoprobe of tumor apoptosis was constructed. The developed multifunctional Au DENPs before and after 99mTc radiolabeling were well characterized. The results demonstrate that the multifunctional Au DENPs display favorable colloidal stability under different conditions, own good cytocompatibility in the given concentration range, and can be effectively labeled by 99mTc with high radiochemical stability. Furthermore, the multifunctional nanoprobe enables the targeted SPECT/CT imaging of apoptotic cancer cells in vitro and tumor apoptosis after doxorubicin (DOX) treatment in the established subcutaneous tumor model in vivo. The designed duramycin-functionalized Au DENPs might have the potential to be employed as a nanoplatform for the detection of apoptosis and early tumor response to chemotherapy

Inter-rater and intra-rater agreement of [99mTc]-labelled NM-01, a single-domain programmed death-ligand 1 (PD-L1) antibody, using quantitative SPECT/CT in non-small cell lung cancer

Abstract Background Immune checkpoint inhibitors, including those against programmed cell death protein-1 (PD-1) or its ligand (PD-L1), are routinely used to treat non-small cell lung cancer (NSCLC). PD-L1 is a validated prognostic and predictive immunohistochemical biomarker of anti-PD-1/PD-L1 therapy but displays temporospatial heterogeneity of expression. Non-invasive radiopharmaceutical techniques, including technetium-99m [99mTc]-labelled anti-PD-L1 single-domain antibody (NM-01) SPECT/CT, have the potential to improve the predictive value of PD-L1 assessment. This study aims to determine the inter- and intra-rater agreement of the quantitative measurement of [99mTc]NM-01 SPECT/CT in NSCLC. Methods Participants (n = 14) with untreated advanced NSCLC underwent [99mTc]NM-01 SPECT/CT at baseline (n = 3) or at baseline plus 9-week follow-up (n = 11). [99mTc]NM-01 uptake (of primary lung, lymph node, thoracic and distant metastases, and healthy reference tissues) was measured using SUVmax and malignant lesion-to-blood pool ratios with Siemens xSPECT Broad Quantification software by three independent raters. Intraclass correlation coefficients (ICC) were calculated and Bland–Altman plot analysis performed to determine inter- and intra-rater agreement. Results There was excellent inter-rater agreement of manual freehand SUVmax scores of primary lung tumour (T; n = 25; ICC 1.00; 95% CI 0.99–1.00), individual lymph node metastases (LN; n = 56; ICC 0.97; 95% CI 0.95–0.98), thoracic metastases (ThMet; n = 9; ICC 0.94; 95% CI 0.83–0.99) and distant metastases (DisMet; n = 21; ICC 0.91; 95% CI 0.83–0.96). The inter-rater ICCs of tumour-to-blood pool (T:BP), LN:BP, ThMet:BP and DisMet:BP measures of [99mTc]NM-01 uptake also demonstrated good or excellent agreement. Manual freehand scoring of T, LN, ThMet, DisMet and their ratios using [99mTc]NM-01 SPECT/CT following a 28-day interval was consistent for all raters with good or excellent intra-rater agreement demonstrated (ICCs range 0.86–1.00). Conclusion Quantitative assessment of [99mTc]NM-01 SPECT/CT in NSCLC, using SUVmax of malignant primary or metastatic lesions and their ratios with healthy reference tissues, demonstrated good or excellent inter- and intra-rater agreement in this study. Further validation with ongoing and future larger cohort studies is now warranted. Clinical trial registration ClinicalTrials.gov identifier no. NCT04436406 (registered 18th June 2020; available at https://clinicaltrials.gov/ct2/show/NCT04436406 ) and NCT04992715 (registered 5th August 2021; available at https://clinicaltrials.gov/ct2/show/NCT04992715 )

[99mTc]-labelled anti-Programmed Death-Ligand 1 single-domain antibody SPECT/CT: a novel imaging biomarker for myocardial PD-L1 expression

Abstract Background Myocardial programmed death-ligand 1 (PD-L1) expression is implicated in immune checkpoint inhibitor (ICI)-associated myocarditis. Measurement of myocardial PD-L1 expression may have potential use as a mechanistic and predictive biomarker. The aim of this study was to determine non-invasive assessment of myocardial PD-L1 expression using [99mTc]-labelled anti-PD-L1 single-domain antibody (NM-01) SPECT/CT. Methods Thoracic [99mTc]NM-01 SPECT/CT was performed in lung cancer patients (n = 10) at baseline and 9-weeks following anti-programmed cell death protein 1 (PD-1) therapy. Baseline and 9-week left ventricular and right ventricular to blood pool ratios (LVmax:BP) and (RVmax:BP) were measured. LVmax was compared to background skeletal muscle (musclemax). Intra-rater reliability was determined by intraclass correlation coefficient (ICC) and Bland–Altman analysis. Results Mean LVmax:BP values were 2.76 ± 0.67 at baseline vs 2.55 ± 0.77 at 9 weeks (p = 0.42). Mean RVmax:BP was 1.82 ± 0.32 at baseline vs 1.76 ± 0.45 at 9 weeks (p = 0.67). Myocardial PD-L1 expression was at least threefold greater than skeletal muscle at baseline for the LV (LVmax to musclemax 3.71 ± 0.77 vs 0.98 ± 0.20 (p < 0.001)) and at least twofold for the RV (LVmax to musclemax 2.49 ± 0.63 vs 0.98 ± 0.20 (p < 0.001)). There was excellent intra-rater reliability for LVmax:BP with ICC 0.99 (95% confidence interval 0.94–0.99, p < 0.001), mean bias -0.05 ± 0.14 (95% limits of agreement -0.32 to 0.21). There were no major adverse cardiovascular events or myocarditis during follow-up. Conclusion This study is the first to report PD-L1 expression of the heart that can be quantified non-invasively without invasive myocardial biopsy, with high reliability and specificity. This technique can be applied to investigate myocardial PD-L1 expression in ICI-associated myocarditis and cardiomyopathies. Clinical trial registration PD-L1 Expression in Cancer (PECan) study (NCT04436406). https://clinicaltrials.gov/ct2/show/NCT04436406 June 18th, 2020

99mTc‑labeled single-domain antibody for SPECT/CT assessment of HER2 expression in diverse cancer types

UNLABELLED: The expression status of human epidermal growth factor receptor 2 (HER2) in cancer predicts response to HER2-targeted therapy. Therefore, its accurate determination is of utmost importance. In recent years, there has been an increase in research on noninvasive techniques for molecular imaging, as this method offers the advantages of a more accurate determination of HER2 status without the need for multiple biopsies. The technetium-labeled single-domain antibody RAD201, previously known as 99mTc-NM-02, has been shown to be safe for use in breast cancer imaging with reasonable radiation doses, favorable biodistribution, and imaging characteristics. METHODS: A total of six HER2-positive, heavily pretreated patients with different cancer types aged between 42 and 69 years (5 women and 1 man; the median age of 55.5) have been examined. In six of seven scans, the patients were administered 500 ml of Gelofusine® solution (40 mg/ml) for radiation protection before the tracer injection (434 ± 42 MBq). Planar scans were acquired with the patient supine at 10 min, 60 min, 160 min, 20 h, and 24 h after injection. A CT scan was acquired at 95 min, followed by local tomographic SPECT imaging. RESULTS: One patient was scanned twice with RAD201, 3 months apart, resulting in a total of seven scans for six patients. Here, we show that the use of RAD201 in our patient group shows the same favorable biodistribution as in a previous study with RAD201 (NCT04040686) and that the radiation dose to the critical organ kidney can be reduced by the application of the plasma expander Gelofusine® by almost 50%. CONCLUSION: RAD201 appears safe for use in humans and is a promising noninvasive tool for discriminating HER2 status in metastatic (breast) cancer, regardless of ongoing HER2-targeted antibody treatment

SPECT/CT imaging of chemotherapy-induced tumor apoptosis using ^99mTc-labeled dendrimer-entrapped gold nanoparticles

<p>Non-invasive imaging of apoptosis in tumors induced by chemotherapy is of great value in the evaluation of therapeutic efficiency. In this study, we report the synthesis, characterization, and utilization of radionuclide technetium-99m (^99mTc)-labeled dendrimer-entrapped gold nanoparticles (Au DENPs) for targeted SPECT/CT imaging of chemotherapy-induced tumor apoptosis. Generation five poly(amidoamine) (PAMAM) dendrimers (G5.NH₂) were sequentially conjugated with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), polyethylene glycol (PEG) modified duramycin, PEG monomethyl ether, and fluorescein isothiocyanate (FI) to form the multifunctional dendrimers, which were then utilized as templates to entrap gold nanoparticles. Followed by acetylation of the remaining dendrimer surface amines and radiolabeling of ^99mTc, the SPECT/CT dual mode nanoprobe of tumor apoptosis was constructed. The developed multifunctional Au DENPs before and after ^99mTc radiolabeling were well characterized. The results demonstrate that the multifunctional Au DENPs display favorable colloidal stability under different conditions, own good cytocompatibility in the given concentration range, and can be effectively labeled by ^99mTc with high radiochemical stability. Furthermore, the multifunctional nanoprobe enables the targeted SPECT/CT imaging of apoptotic cancer cells <i>in vitro</i> and tumor apoptosis after doxorubicin (DOX) treatment in the established subcutaneous tumor model <i>in vivo</i>. The designed duramycin-functionalized Au DENPs might have the potential to be employed as a nanoplatform for the detection of apoptosis and early tumor response to chemotherapy.</p