ImmunoPET of CD146 in Orthotopic and Metastatic Breast Cancer Models

Single-cell and spatial transcriptomics reveals the key role of MCAM+ tip-like endothelial cells in osteosarcoma metastasis

Osteosarcoma, the most common primary malignant bone tumor in children and adolescents, is highly aggressive and prone to metastasis. Endothelial cells (ECs) are involved in angiogenesis and play a key role in promoting the metastasis of tumor. However, research on tip-like ECs within osteosarcoma was extremely rare. In this study, a single-cell atlas of ECs was constructed using single-cell transcriptomic data. It was found that tip-like ECs were abundant in the primary tumors and metastatic foci. Gene sets score analysis indicated their enrichment in pathways associated with angiogenesis and metastasis. What's more, MCAM was highly expressed in tip-like ECs and was likely to promote the metastasis of osteosarcoma. MCAM was also found to be highly expressed in the ECs of metastatic lymph nodes when compared to normal lymph node samples. Meanwhile, spatial transcriptomics data confirmed the presence of MCAM-positive ECs in metastatic lymph node, closely localized to osteoblasts. In vitro assays, including qRT-PCR, tube formation, and immunofluorescence, validated the role of the MCAM gene in promoting angiogenesis. In conclusion, tip-like ECs may promote tumor metastasis by enhancing angiogenesis. MCAM was a functional gene for tip-like ECs and could serve as a target for the treatment of osteosarcoma.

ImmunoPET Imaging of Trop2 Expression in Bladder Cancer Using [64Cu]Cu-NOTA-Trodelvy

Trop2 exhibits significantly elevated expression in numerous solid malignancies, playing a crucial role in tumor advancement, whereas its presence in healthy tissues is minimal. In this study, we investigated Trop2 expression in bladder cancer models using [64Cu]Cu-NOTA-Trodelvy for immunoPET imaging. In HT-1376 models, [64Cu]Cu-NOTA-Trodelvy effectively visualized tumor as early as 12 h p.i. (10.30 ± 1.45% ID/g), with tumor uptake increasing and peaking at 48 h p.i. (13.73 ± 1.16% ID/g), highlighting its potential for tumor imaging. Control groups also demonstrated low tumor uptake (5.27 ± 1.14% ID/g at 48 h in the blocking group; 6.33 ± 0.74% ID/g at 48 h in UM-UC-3; 4.50 ± 0.30% ID/g at 48 h in the [64Cu]Cu-NOTA-IgG group). Long-term fluorescence imaging further confirmed the tumor uptake rate in the IRDye 800CW-Trodelvy group was significantly higher than in the IRDye 800CW-Trodelvy blockade group (P < 0.001). Our findings demonstrated that [64Cu]Cu-NOTA-Trodelvy enables specific and prolonged tumor accumulation in bladder cancer models, providing precise and noninvasive monitoring of Trop2 expression.

Injectable doxorubicin-loaded hyaluronic acid-based hydrogel for locoregional therapy and inhibiting metastasis of breast cancer

Therapy and metastasis pose significant challenges for breast cancer therapy. Locoregional chemotherapy presents a promising strategy to address these dilemmas. In this study, a doxorubicin-loaded injectable hydrogel based on hyaluronic acid (DOX-MCHAgel) was fabricated for locoregional chemotherapy and inhibiting the metastasis of breast cancer. The high bio-safety of cargo-free hydrogels (MCHAgel) would enhance patient compliance. The sustained DOX release behaviors from DOX-MCHAgel (over 10 days) could reduce dosing frequency and achieve long-term therapeutic effects. The potent in vivo anti-tumor activity of DOX-MCHAgel was verified by the smallest tumor volumes, the largest number of apoptotic cells, and the strongest fluorescence intensity in TUNEL sections. Notably, the injectable DOX-MCHAgel not only greatly suppressed the growth of 4T1 tumor tissues, but also effectively curbed the liver and lung metastasis in vivo. Moreover, the survival of 4T1-tumor bearing mice was extended without obvious systemic toxicity. In brief, the novel injectable hydrogel developed in this study offers a new strategy for locoregional therapy and inhibiting metastasis of breast cancer.

ImmunoPET imaging of Trop2 expression in triple-negative breast cancer using [64Cu]Cu-NOTA-Trodelvy-F(ab')2

PURPOSE

The Trop2-targeting antibody-drug conjugate (ADC) sacituzumab govitecan (Trodelvy) has demonstrated remarkable efficacy in patients with metastatic triple-negative breast cancer (TNBC). ImmunoPET imaging offers a noninvasive method to visualize the expression and distribution of target antigens in vivo. In this study, we developed F(ab')2 fragments of Trodelvy for immunoPET imaging to detect Trop2 expression in TNBC models, aiming to achieve a shorter imaging window.

MATERIALS AND METHODS

Trodelvy-F(ab')2 was prepared using the IdeS protease kit and purified with Magne Protein A beads and MagneHis™ Ni Particles. The products were characterized by non-reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis and high-performance liquid chromatography. Trodelvy-F(ab')2 was subsequently conjugated with p-SCN-Bn-NOTA (NOTA) for radiolabeling with 64Cu. ImmunoPET imaging using [64Cu]Cu-NOTA-Trodelvy-F(ab')2 was conducted at multiple time points to assess its in vivo targeting capability. Immunohistochemical and immunofluorescence analyses were performed on tumor tissues obtained from tumor-bearing mice.

RESULTS

The radiochemical yield of [64Cu]Cu-NOTA-Trodelvy-F(ab')2 exceeded 90%, with a radiochemical purity greater than 99%. High Trop2 expression was observed in MDA-MB-468 cells, whereas MDST8 cells exhibited low expression. The apparent dissociation constant (KD) of [64Cu]Cu-NOTA-Trodelvy-F(ab')2 for MDA-MB-468 cells was determined to be 14.60 nM. ImmunoPET imaging revealed clear uptake of [64Cu]Cu-NOTA-Trodelvy-F(ab')2 in MDA-MB-468 tumors as early as 4 h post-injection (p.i.) (8.20 ± 0.98%ID/g), peaking at 12 h p.i. (11.13 ± 0.45%ID/g). Uptake was significantly higher compared to the MDST8 group (3.37 ± 0.45%ID/g at 4 h; 5.77 ± 0.74%ID/g at 12 h) and the blocking group (2.67 ± 0.21%ID/g at 4 h; 3.07 ± 0.37%ID/g at 12 h). [64Cu]Cu-NOTA-Trodelvy-F(ab')2 achieved significantly higher tumor-to-heart ratios in MDA-MB-468 tumors (3.87 ± 0.58 vs. 0.74 ± 0.19, P = 0.0019) at 12 h p.i., compared to [64Cu]Cu-NOTA-Trodelvy, indicating superior tumor contrast.

CONCLUSIONS

Our findings indicate that [64Cu]Cu-NOTA-Trodelvy-F(ab')2 exhibits rapid, specific, and sustained tumor accumulation in TNBC models, enabling precise and noninvasive monitoring of Trop2 expression.

Preclinical evaluation of zirconium-89 labeled anti-Trop2 antibody-drug conjugate (Trodelvy) for imaging in gastric cancer and triple-negative breast cancer

PURPOSE

Trophoblast cell-surface antigen 2 (Trop2) is overexpressed in various solid tumors and contributes to tumor progression, while its expression remains low in normal tissues. Trop2-targeting antibody-drug conjugate (ADC), sacituzumab govitecan-hziy (Trodelvy), has shown efficacy in targeting this antigen. Leveraging the enhanced specificity of ADCs, we conducted the first immunoPET imaging study of Trop2 expression in gastric cancer (GC) and triple-negative breast cancer (TNBC) models using 89Zr-labeled Trodelvy ([89Zr]Zr-DFO-Trodelvy). This approach enables preclinical screening to identify patients who may benefit from targeted therapies.

MATERIALS AND METHODS

Trop2 expression levels in GC and TNBC cell lines (NCI-N87, HGC-27, MDST8, and MDA-MB-468) were assessed via flow cytometry and immunofluorescence staining. Labeling of DFO-Trodelvy with 89Zr was performed in Na2CO3 buffer at pH 7 (37 °C, 1.5 h). In vitro stability was analyzed using radio-thin layer chromatography. Biological properties were evaluated through cell uptake, saturation binding assays, and biodistribution experiments. ImmunoPET imaging with [89Zr]Zr-DFO-Trodelvy was performed at various time points to confirm its in vivo targeting. Immunohistochemical and immunofluorescence analyses were conducted on tumor tissues from tumor-bearing mice.

RESULTS

The radiochemical yield of [89Zr]Zr-DFO-Trodelvy exceeded 90%, with a radiochemical purity (RCP) greater than 99%. Trop2 expression was high in MDA-MB-468 and NCI-N87 cells, while it was low in MDST8 and HGC-27 cells. The KD values of [89Zr]Zr-DFO-Trodelvy were 9.44 nM for MDA-MB-468 and 3.51 nM for NCI-N87 cells. ImmunoPET imaging with [89Zr]Zr-DFO-Trodelvy provided clear visualization of tumor morphology in MDA-MB-468 and NCI-N87 models (n = 3) as early as 6 h post-injection. Tumor uptake of [89Zr]Zr-DFO-Trodelvy increased over time, peaking at 48 h (MDA-MB-468: 10.03 ± 1.26%ID/g; NCI-N87: 14.30 ± 2.09%ID/g), and was significantly higher than in the MDST8 (5.27 ± 0.71%ID/g) and HGC-27 (4.37 ± 0.54%ID/g) models. Co-injection with 2 mg of unlabeled Trodelvy significantly reduced uptake in NCI-N87 and MDA-MB-468 tumors (P < 0.001). A high target-to-non-target ratio was observed at 48 h, showing specific tumor uptake and minimal off-target accumulation. Fluorescence imaging further confirmed higher tumor uptake in the IRDye800CW-Trodelvy group compared to the IRDye800CW-Trodelvy-blocking group (P < 0.001).

CONCLUSIONS

[89Zr]Zr-DFO-Trodelvy for immunoPET imaging in TNBC and GC tumor models demonstrated specific, rapid, and sustained accumulation in tumors with high Trop2 expression, allowing for noninvasive monitoring of Trop2 status. The increased tumor-to-background ratio observed in immunoPET imaging suggests strong potential for clinical translation. Additionally, optical imaging, with its superior spatial resolution compared to PET, was employed to aid in precise probe localization and potentially enhancing differentiation between healthy and malignant tissues during surgical procedures.

Netrin-1-CD146 and netrin-1-S100A9 are associated with early stage of lymph node metastasis in colorectal cancer

BACKGROUND

The netrin-1/CD146 pathway regulates colorectal cancer (CRC) liver metastasis, angiogenesis, and vascular development. However, few investigations have yet examined the biological function of netrin-1/CD146 complex in CRC. In this work, we investigated the relationship between the netrin-1/CD146 axis and S100 proteins in sentinel lymph node, and revealed a possible new clue for vascular metastasis of CRC.

METHODS

The expression levels of netrin-1 and CD146 proteins in CRC, as well as S100A8 and S100A9 proteins in the sentinel lymph nodes were determined by immunohistochemistry. Using GEPIA and UALCAN, we analyzed netrin-1 and CD146 gene expression in CRC, their association with CRC stage, and their expression levels and prognosis in CRC patients.

RESULTS

The expression level of netrin-1 in N1a+1b (CRC lymphatic metastasis groups, exculded N1c) was positively increased with N0 (p = 0.012). The level of netrin-1 protein was positively correlated with CD146 protein (p < 0.05). The level of S100A9 protein was positively correlated with CD146 protein (r = 0.492, p = 0.007). Moreover, netrin-1 expression was obviously correlated with S100A9 expression in the N1 stage (r = 0.867, p = 0.000). CD146 level was correlated with S100A9 level in the N2 stage (r = 0.731, p = 0.039). CD146 mRNA expression was higher in normal colorectal tissues than in CRC (p < 0.05). Netrin-1 and CD146 expression were not significantly associated with the tumor stages and prognosis of patients with CRC (p > 0.05).

CONCLUSIONS

The netrin-1/CD146 and netrin-1/S100A9 axis in CRC tissues might related with early stage of lymph node metastasis, thus providing potential novel channels for blocking lymphatic metastasis and guiding biomarker discovery in CRC patients.

Theranostic role of 89Zr- and 177Lu-labeled aflibercept in breast cancer

PURPOSE

Triple-negative breast cancer (TNBC) has a poor prognosis due to the absence of effective therapeutic targets. Vascular endothelial growth factor (VEGF) family are expressed in 30-60% of TNBC, therefore providing potential therapeutic targets for TNBC. Aflibercept (Abe), a humanized recombinant fusion protein specifically bound to VEGF-A, B and placental growth factor (PIGF), has proven to be effective in the treatment in some cancers. Therefore, 89Zr/177Lu-labeled Abe was investigated for its theranostic role in TNBC.

METHODS

Abe was radiolabeled with 89Zr and 177Lu via the conjugation of chelators. Flow cytometry and cell immunofluorescent staining were performed to evaluate the binding affinity of Abe. Sequential PET imaging and fluorescent imaging were conducted in TNBC tumor bearing mice following the injection of 89Zr-labeled Abe and Cy5.5-labeled Abe. Treatment study was performed after the administration of 177Lu-labeled Abe. Tumor volume and survival were monitored and SPECT imaging and biodistribution studies were conducted. Safety evaluation was performed including body weight, blood cell measurement, and hematoxylin-eosin (H&E) staining of major organs. Expression of VEGF and CD31 was tested by immunohistochemical staining. Dosimetry was estimated using the OLINDA software.

RESULTS

FITC-labeled Abe showed a strong binding affinity to VEGF in TNBC 4T1 cells and HUVECs by flow cytometry and cell immunofluorescence. Tumor uptake of 89Zr-labeled Abe peaked at 120 h (SUVmax = 3.2 ± 0.64) and persisted before 168 h (SUVmax = 2.54 ± 0.42). The fluorescence intensity of the Cy5.5-labeled Abe group surpassed that of the Cy5.5-labeled IgG group, implying that Cy5.5-labeled Abe is a viable candidate monitoring in vivo tumor targeting and localization. 177Lu-labeled Abe (11.1 MBq) served well as the therapeutic component to suppress tumor growth with standardized tumor volume at 16 days, significantly smaller than PBS group (about 815.66 ± 3.58% vs 3646.52 ± 11.10%, n = 5, P < 0.01). Moreover, SPECT images confirmed high contrast between tumors and normal organs, indicating selective tumor uptake of 177Lu-labeled Abe. No discernible abnormalities in blood cells, and no evident histopathological abnormality observed in liver, spleen, and kidney. Immunohistochemical staining showed that 177Lu-labeled Abe effectively inhibited the expression of VEGF and CD31 of tumor, suggesting that angiogenesis may be suppressed by 177Lu-labeled Abe. The whole-body effective dose for an adult human was estimated to be 0.16 mSv/MBq.

CONCLUSION

89Zr/177Lu-labeled Abe could be a TNBC-specific marker with diagnostic value and provide insights into targeted therapy in the treatment of TNBC. Further clinical evaluation and translation may be of high significance for TNBC.

Molecular imaging of tumour-associated pathological biomarkers with smart nanoprobe: From "Seeing" to "Measuring"

Although the extraordinary progress has been made in molecular biology, the prevention of cancer remains arduous. Most solid tumours exhibit both spatial and temporal heterogeneity, which is difficult to be mimicked in vitro. Additionally, the complex biochemical and immune features of tumour microenvironment significantly affect the tumour development. Molecular imaging aims at the exploitation of tumour-associated molecules as specific targets of customized molecular probe, thereby generating image contrast of tumour markers, and offering opportunities to non-invasively evaluate the pathological characteristics of tumours in vivo. Particularly, there are no "standard markers" as control in clinical imaging diagnosis of individuals, so the tumour pathological characteristics-responsive nanoprobe-based quantitative molecular imaging, which is able to visualize and determine the accurate content values of heterogeneous distribution of pathological molecules in solid tumours, can provide criteria for cancer diagnosis. In this context, a variety of "smart" quantitative molecular imaging nanoprobes have been designed, in order to provide feasible approaches to quantitatively visualize the tumour-associated pathological molecules in vivo. This review summarizes the recent achievements in the designs of these nanoprobes, and highlights the state-of-the-art technologies in quantitative imaging of tumour-associated pathological molecules.

CD146-targeted nuclear medicine imaging in cancer: state of the art

The transmembrane glycoprotein adhesion molecule CD146 is overexpressed in a wide variety of cancers. Through molecular imaging, a specific biomarker's expression and distribution can be viewed in vivo non-invasively. Radionuclide-labeled monoclonal antibodies or relevant fragments that target CD146 may find potential applications in cancer imaging, thereby offering tremendous value in cancer diagnosis, staging, prognosis evaluation, and prediction of drug resistance. This review discusses the recent developments of CD146-targeted molecular imaging via nuclear medicine, especially in malignant melanoma, brain tumor, lung cancer, liver cancer, breast cancer, and pancreatic cancer. Many studies have proved that CD146 targeting may present a promising strategy for cancer theranostics.

Dual-Targeting PET Tracers Enable Enzyme-Mediated Self-Assembly for the PET Imaging of Legumain Activity

Legumain, a lysosomal cysteine protease overexpressed in a variety of tumors, has been considered a promising biomarker for various cancers. Precise detection of legumain activity in the lysosome represents an important strategy for early diagnosis and prognosis of tumors. Small-molecule probes with the property of target-enabled self-assembly hold great potential for molecular imaging. In this study, we reported two dual-targeting radiotracers ([18F]SF-AAN-M and [18F]SF-AAN-HEM) with a property of legumain-mediated self-assembly for positron emission tomography (PET) imaging. Both the radiotracers were synthesized with high labeling yield (>50%) and the radiochemical purity was over 99% via one-step straightforward 18F-labeling. Both tracers were efficiently activated by the reducing agent and legumain to self-assemble into aggregates and showed enhanced retention in legumain-overexpressed MDA-MB-468 cells and tumors, indicating that the introduction of lysosome-targeting morpholine increased the tumor uptake and extended the retention of radiotracers in legumain-overexpressed tumors. In addition, [18F]SF-AAN-HEM with a hydrophilic (histidine-glutamate)3 tag displayed significantly reduced liver uptake with no conspicuous reduction in tumor uptake, affording high signal-to-noise ratios (tumor/liver and tumor/muscle). All of these results suggest that dual-targeting tracer [18F]SF-AAN-HEM could provide a promising tool for in vivo monitoring legumain activity in tumors.

Advances in PET/CT Imaging for Breast Cancer

One out of eight women will be affected by breast cancer during her lifetime. Imaging plays a key role in breast cancer detection and management, providing physicians with information about tumor location, heterogeneity, and dissemination. In this review, we describe the latest advances in PET/CT imaging of breast cancer, including novel applications of 18F-FDG PET/CT and the development and testing of new agents for primary and metastatic breast tumor imaging and therapy. Ultimately, these radiopharmaceuticals may guide personalized approaches to optimize treatment based on the patient's specific tumor profile, and may become a new standard of care. In addition, they may enhance the assessment of treatment efficacy and lead to improved outcomes for patients with a breast cancer diagnosis.

PET/CT in Patients with Breast Cancer Treated with Immunotherapy

Significant advances in breast cancer (BC) treatment have been made in the last decade, including the use of immunotherapy and, in particular, immune checkpoint inhibitors that have been shown to improve the survival of patients with triple negative BC. This narrative review summarizes the studies supporting the use of immunotherapy in BC. Furthermore, the usefulness of 2-deoxy-2-[¹⁸F]fluoro-D-glucose (2-[¹⁸F]FDG) positron emission/computerized tomography (PET/CT) to image the tumor heterogeneity and to assess treatment response is explored, including the different criteria to interpret 2-[¹⁸F]FDG PET/CT imaging. The concept of immuno-PET is also described, by explaining the advantages of mapping treatment targets with a non-invasive and whole-body tool. Several radiopharmaceuticals in the preclinical phase are referred too, and, considering their promising results, translation to human studies is needed to support their use in clinical practice. Overall, this is an evolving field in BC treatment, despite PET imaging developments, the future trends also include expanding immunotherapy to early-stage BC and using other biomarkers.

Theranostic application of 64Cu/177Lu-labeled anti-Trop2 monoclonal antibody in pancreatic cancer tumor models

PURPOSE

Pancreatic cancer is a malignant tumor with a high degree of malignancy, strong heterogeneity, and high lethality. Trop2 is a transmembrane glycoprotein associated with the occurrence, development, and poor prognosis of pancreatic cancer. This study aims to develop 64Cu/177Lu-labeled anti-Trop2 monoclonal antibody (hIMB1636) for positron emission tomography (PET) imaging and radioimmunotherapy (RIT) application in pancreatic cancer tumor models.

METHODS

The binding kinetics of hIMB1636 to Trop2 antigen was measured by Biolayer interferometry (BLI). Western blotting was used to screen the Trop2 expression of pancreatic cancer cell lines. Flow cytometry and cell immunofluorescence were used to evaluate the binding ability of hIMB1636 and Trop2 on the cell surface. hIMB1636 were conjugated with p-SCN-Bn-NOTA (NOTA) and DOTA-NHS-ester (DOTA) for 64Cu and 177Lu radiolabeling respectively. ImmunoPET imaging and RIT studies were performed using 64Cu-NOTA-hIMB1636 and 177Lu-DOTA-hIMB1636 in subcutaneous pancreatic cancer tumor models.

RESULTS

hIMB1636 had a strong binding affinity to Trop2 according to the results of BLI. The T3M-4 cell line showed the strongest expression of Trop2 and specific binding ability of hIMB1636 according to the results of Western blotting, flow cytometry, and cell immunofluorescence. The radiochemical purity of 64Cu-NOTA-hIMB1636 and 177Lu-DOTA-hIMB1636 exceeded 95%. PET imaging showed gradually an accumulation of 64Cu-NOTA-hIMB1636 in T3M-4 tumor models. The maximum tumor uptake was 8.95 ± 1.07%ID/g (n = 4) at 48 h post injection (p.i.), which had significant differences with T3M-4-blocked and PaTu8988-negative groups (P < 0.001). The high-177Lu-hIMB1636 group demonstrated the strongest tumor suppression with standardized tumor volume about 94.24 ± 14.62% (n = 5) at 14 days p.i., significantly smaller than other groups (P < 0.05). Ex vivo biodistribution and histological staining verified the in vivo PET imaging and RIT results.

CONCLUSIONS

This study demonstrated that 64Cu/177Lu-labeled hIMB1636 could noninvasively evaluate the expression level of Trop2 and inhibit the Trop2-overexpressed tumor growth in pancreatic cancer tumor models. Further clinical evaluation and translation of Trop2-targeted drug may be of great help in the stratification and management of pancreatic cancer patients.

Soluble CD146 in the detection and grading of intravascular and tissue congestion in patients with acute dyspnoea: analysis of the prospective observational Lithuanian Echocardiography Study of Dyspnoea in Acute Settings (LEDA) cohort

OBJECTIVES

To evaluate the potential of soluble cluster of differentiation 146 (sCD146) in the detection and grading of congestion in patients with acute dyspnoea.

DESIGN

Subanalysis of the prospective observational Lithuanian Echocardiography Study of Dyspnoea in Acute Settings (LEDA) cohort.

SETTING

Two Lithuanian university centres.

PARTICIPANTS

Adult patients with acute dyspnoea admitted to the emergency department.

METHODS

Congestion was assessed using clinical and sonographic parameters. All patients underwent sCD146 and N-terminal pro-B-type natriuretic peptide (NT-proBNP) testing.

RESULTS

The median value of sCD146 concentration in the study cohort (n=437) was 405 (IQR 315-509) ng/mL. sCD146 was higher in patients with peripheral oedema than in those without (median (IQR) 472 (373-535) vs 400 (304-501) ng/mL, p=0.009) and with pulmonary rales than in those without (439 (335-528) vs 394 (296-484) ng/mL, p=0.001). We found a parallel increase of estimated right atrial pressure (eRAP) and sCD146 concentration: sCD146 was 337 (300-425), 404 (290-489) and 477 (363-572) ng/mL in patients with normal, moderately elevated and high eRAP, respectively (p=0.001). In patients with low NT-proBNP, high sCD146 distinguished a subgroup with a higher prevalence of oedema as compared with patients with low levels of both biomarkers (76.0% vs 41.0%, p=0.010). Moreover, high sCD146 indicated a higher prevalence of elevated eRAP, irrespective of NT-proBNP concentration (p<0.05).

CONCLUSION

sCD146 concentration reflects the degree of intravascular and tissue congestion assessed by clinical and echocardiographic indices, with this association maintained in patients with low NT-proBNP. Our data support the notion that NT-proBNP might represent heart stretch while sCD146 rather represents peripheral venous congestion.

Immuno-PET Imaging of TNF-α in Colitis Using 89Zr-DFO-infliximab

Tumor necrosis factor-alpha (TNF-α) neutralization has become increasingly important in the treatment of inflammatory bowel diseases (IBD). A series of monoclonal antibodies were approved in the clinic for anti-TNF-α therapy. However, a comprehensive assessment of TNF-α levels throughout the colon, which facilitates the diagnosis of IBD and predicts anti-TNF-α efficacy, remains challenging. Here, we radiolabeled infliximab with long-lived radionuclides ⁸⁹Zr for immuno-positron emission tomography (PET) imaging of TNF-α in vivo. The increased TNF-α level was detected in the inflammatory colon of the dextran sodium sulfate-induced colitis mice. The immuno-PET imaging of ⁸⁹Zr-desferrioxamine-infliximab reveals a high uptake (7.1 ± 0.3%ID/g) in the inflammatory colon, which is significantly higher than in the healthy control and blocked groups. The colon-to-muscle ratio reached more than 10 and was maintained at a high level for 10 h after injection. The ex vivo biodistribution study also verified the superior uptake in the inflammatory colon. This study provides an in vivo immune-PET approach to molecular imaging of the pro-inflammatory cytokine TNF-α. It is promising in diagnosing and predicting efficacy in both IBD and other autoimmune diseases.

An Enzyme-Activatable Aggregation-Induced-Emission Probe: Intraoperative Pathological Fluorescent Diagnosis of Pancreatic Cancer via Specific Cathepsin E

Pancreatic cancer (PC) is one of the most devastating malignant tumors. However, fluorescence probes for early clinical diagnosis of PC often encounter difficulties in accuracy and penetrability. In this work, an enzyme-activated aggregation-induced-emission (AIE) probe, QM-HSP-CPP, for high-contrast fluorescence diagnosis of PC is developed by monitoring specific overexpressed enzyme Cathepsin E (CTSE). The probe is composed of an AIE fluorophore QM-COOH (QM = quinoline-malononitrile), CTSE-triggered hydrophobic peptide (HSP), and hydrophilic biocompatible cell penetrating peptide (CPP). The CPP unit can well-modulate the molecular dispersion properties, giving initial fluorescence-off state in the aqueous biosystem, thus endowing high signal-to-noise ratio, and finally overcoming the poor targeting selectivity of traditional AIE probes. CPP can ensure cell/tissue penetrating ability, thus allowing on-site monitoring of endogenous CTSE in PC cells, tissues, and living animal models. When the QM-HSP-CPP probe is specifically cleaved by CTSE, it can generate AIE signals in situ with high-specificity and long-term tracking ability, and successfully achieve intraoperative diagnosis of human PC sections, tracking PC in heterotopic nude mice models. The CTSE-enzyme-triggered AIEgens' liberation strategy improves accuracy and addresses the penetration problem simultaneously, which can expand the database of multitudinous biocompatible AIE-active probes, especially for establishing intraoperative pathological fluorescent diagnosis.

Early Detection and Investigation of Extracellular Vesicles Biomarkers in Breast Cancer

Breast cancer (BC) is the most commonly diagnosed malignant tumor in women worldwide, and the leading cause of cancer death in the female population. The percentage of patients experiencing poor prognosis along with the risk of developing metastasis remains high, also affecting the resistance to current main therapies. Cancer progression and metastatic development are no longer due entirely to their intrinsic characteristics, but also regulated by signals derived from cells of the tumor microenvironment. Extracellular vesicles (EVs) packed with DNA, RNA, and proteins, are the most attractive targets for both diagnostic and therapeutic applications, and represent a decisive challenge as liquid biopsy-based markers. Here we performed a study based on a multiplexed phenotyping flow cytometric approach to characterize BC-derived EVs from BC patients and cell lines, through the detection of multiple antigens. Our data reveal the expression of EVs-related biomarkers derived from BC patient plasma and cell line supernatants, suggesting that EVs could be exploited for characterizing and monitoring disease progression.

64Cu-labeled daratumumab F(ab')2 fragment enables early visualization of CD38-positive lymphoma

PURPOSE

Abnormal CD38 expression in some hematologic malignancies, including lymphoma, has made it a biomarker for targeted therapies. Daratumumab (Dara) is the first FDA-approved CD38-specific monoclonal antibody, enabling successfully immunoPET imaging over the past years. Radiolabeled Dara however has a long blood circulation and delayed tumor uptake which can limit its applications. The focus of this study is to develop ⁶⁴Cu-labeled Dara-F(ab')₂ for the visualization of CD38 in lymphoma models.

METHODS

F(ab')₂ fragment was prepared from Dara using an IdeS enzyme and purified with Protein A beads. Western blotting, flow cytometry, and surface plasmon resonance (SPR) were performed for in vitro assay. Probes were labeled with ⁶⁴Cu after the chelation of 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA). Small animal PET imaging and quantitative analysis were performed after injection of ⁶⁴Cu-labeled Dara-F(ab')₂, IgG-F(ab')₂, and Dara for evaluation in lymphoma models.

RESULTS

Flow cytometry and SPR assay proved the specific binding ability of Dara-F(ab')₂ and NOTA-Dara-F(ab')₂ in vitro. Radiolabeling yield of [⁶⁴Cu]Cu-NOTA-Dara-F(ab')₂ was over 90% and with a specific activity of 4.0 ± 0.6 × 10³ MBq/μmol (n = 5). PET imaging showed [⁶⁴Cu]Cu-NOTA-Dara-F(ab')₂ had a rapid and high tumor uptake as early as 2 h (6.9 ± 1.2%ID/g) and peaked (9.5 ± 0.7%ID/g) at 12 h, whereas [⁶⁴Cu]Cu-NOTA-Dara reached its tumor uptake peaked at 48 h (8.3 ± 1.4%ID/g, n = 4). In comparison, IgG-F(ab')₂ and HBL-1 control groups found no noticeable tumor uptake. [⁶⁴Cu]Cu-NOTA-Dara-F(ab')₂ had significantly lower uptake in blood pool, bone, and muscle than [⁶⁴Cu]Cu-NOTA-Dara and its tumor-to-blood and tumor-to-muscle ratios were significantly higher than controls.

CONCLUSIONS

[⁶⁴Cu]Cu-NOTA-Dara-F(ab')₂ showed a rapid and high tumor uptake in CD38-positive lymphoma models with favorable imaging contrast, showing its promise as a potential PET imaging agent for future clinical applications.