Formyl peptide enhances cancer immunotherapy by activating antitumoral neutrophils, and T cells.

Neutrophils are heterogeneous and plastic, with the ability to polarize from antitumour to protumour phenotype and modulate tumour microenvironment components. While some advances have been made, the neutrophil-targeting therapy remains underexplored. Activation of formyl peptide receptors (FPRs) by formylated peptides is needed for local control of infection through the recruitment of activated neutrophils while the potential contribution of antitumour activity remains underexplored. Here, we demonstrate that neutrophils can be harnessed to suppress tumour growth through the action of the formyl peptide (FP) on the formyl peptide receptor (FPR). Mechanistically, FP efficiently recruits neutrophils to produce reactive oxygen species production (ROS), resulting in the direct killing of tumours. Antitumour functions disappeared when neutrophils were depleted by anti-Ly6G antibodies. Interestingly, extensive T-cell activation was observed in mouse tumours treated with FP, showing the potential to alter the immune suppressed tumour microenvironment (TME) and further sensitize mice to anti-PD1 therapy. Transcriptomic and flow cytometry analyses revealed the mechanisms of FP-sensitized anti-PD1 therapy, mainly including stimulated neutrophils and an altered immune-suppressed tumour microenvironment. Collectively, these data establish FP as an effective combination partner for sensitizing anti-PD1 therapy by stimulating tumour-infiltrated neutrophils.

A gB nanoparticle vaccine elicits a protective neutralizing antibody response against EBV.

Epstein-Barr virus (EBV) is a global public health concern, as it is known to cause multiple diseases while also being etiologically associated with a wide range of epithelial and lymphoid malignancies. Currently, there is no available prophylactic vaccine against EBV. gB is the EBV fusion protein that mediates viral membrane fusion and participates in host recognition, making it critical for EBV infection in both B cells and epithelial cells. Here, we present a gB nanoparticle, gB-I53-50 NP, that displays multiple copies of gB. Compared with the gB trimer, gB-I53-50 NP shows improved structural integrity and stability, as well as enhanced immunogenicity in mice and non-human primate (NHP) preclinical models. Immunization and passive transfer demonstrate a robust and durable protective antibody response that protects humanized mice against lethal EBV challenge. This vaccine candidate demonstrates significant potential in preventing EBV infection, providing a possible platform for developing prophylactic vaccines for EBV.

mRNA-based Vaccines Targeting the T-cell Epitope-rich Domain of Epstein Barr Virus Latent Proteins Elicit Robust Anti-Tumor Immunity in Mice.

Epstein-Barr virus (EBV) is associated with various malignancies and infects >90% of the global population. EBV latent proteins are expressed in numerous EBV-associated cancers and contribute to carcinogenesis, making them critical therapeutic targets for these cancers. Thus, this study aims to develop mRNA-based therapeutic vaccines that express the T-cell-epitope-rich domain of truncated latent proteins of EBV, including truncatedlatent membrane protein 2A (Trunc-LMP2A), truncated EBV nuclear antigen 1 (Trunc-EBNA1), and Trunc-EBNA3A. The vaccines effectively activate both cellular and humoral immunity in mice and show promising results in suppressing tumor progression and improving survival time in tumor-bearing mice. Furthermore, it is observed that the truncated forms of the antigens, Trunc-LMP2A, Trunc-EBNA1, and Trunc-EBNA3A, are more effective than full-length antigens in activating antigen-specific immune responses. In summary, the findings demonstrate the effectiveness of mRNA-based therapeutic vaccines targeting the T-cell-epitope-rich domain of EBV latent proteins and providing new treatment options for EBV-associated cancers.

Automated Synthesis and Preclinical Evaluation of Optimized Integrin α6-Targeted Positron Emission Tomography Imaging of Pancreatic Cancer.

Integrin α6 has been considered a promising biomarker, is overexpressed in many tumors, and plays a vital role in tumor formation, recurrence, and metastasis. In this study, we identified a novel high-affinity integrin α6-targeted peptide named RD2 (Arg-Trp-Tyr-Asp-PEG4)2-Lys-Lys and developed a 18F-radiolabeled peptide tracer ([18F]-AlF-NOTA-RD2) and evaluated its potential application in positron emission tomography (PET) imaging of pancreatic cancer. [18F]-AlF-NOTA-RD2 was produced using GMP (Good Manufacturing Practice of Medical Products)-compliant automatic radiosynthesis on a single GE FASTLab2 cassette-type synthesis module. The stability of [18F]-AlF-NOTA-RD2 was analyzed in phosphate-buffered saline (PBS) and fetal bovine serum (FBS). The cell uptake assay of the tracer was assessed using PANC-1 cells. In addition, small-animal PET imaging and biodistribution studies of [18F]-AlF-NOTA-RD2 were performed in pancreatic cancer subcutaneous tumor-bearing mice. The PET tracer [18F]-AlF-NOTA-RD2 was obtained with a radiochemical yield of 23.7 ± 4.7%, radiochemical purity of >99%, and molar activity of 165.7 ± 59.1 GBq/µmol. [18F]-AlF-NOTA-RD2 exhibited good in vitro stability in PBS and FBS. LogP octanol water value for the tracer was -2.28 ± 0.05 (n = 3). The binding affinity of RD2 to the integrin α6 protein (Kd = 0.13 ± 3.65 µM, n = 3) was significantly higher than that of the RWY (CRWYDENAC) (Kd = 6.97 ± 1.44 µM, n = 3). Small-animal PET imaging and biodistribution also revealed that [18F]-AlF-NOTA-RD2 displayed rapid and good tumor uptake and lower liver background uptake in PANC-1 tumor-bearing mice. [18F]-AlF-NOTA-RD2 showed significant radioactivity accumulation in tumors and was successfully blocked by NOTA-RD2. Compared with [18F]-FDG, [18F]-AlF-NOTA-RD2 PET imaging and biodistribution studies in PANC-1 xenograft tumor-bearing mice confirmed a good tumor-to-muscle ratio (8.69 ± 2.03 vs 1.41 ± 0.23, respectively) at 0.5 h and (2.99 ± 3.02 vs 1.43 ± 0.17, respectively) at 1 h post injection. Autoradiography of human pancreatic cancer tumor tissues further confirmed high accumulation of [18F]-AlF-NOTA-RD2. In summary, we developed an optimized integrin α6-targeted imaging tracer and obtained high radioactivity products with a cassette-type synthesis module; moreover, the tracer exhibited good binding affinity with integrin α6 and good target specificity for PANC-1 cells in xenograft pancreatic tumor-bearing mice, demonstrating its promising application as a noninvasive PET radiotracer of integrin α6 expression in pancreatic cancer.

EDB-FN targeted probes for the surgical navigation, radionuclide imaging, and therapy of thyroid cancer.

PURPOSE: Extradomain B of fibronectin (EDB-FN) is a promising diagnostic and therapeutic biomarker for thyroid cancer (TC). Here, we identified a high-affinity EDB-FN targeted peptide named EDBp (AVRTSAD) and developed three EDBp-based probes, Cy5-PEG4-EDBp(Cy5-EDBp), [18F]-NOTA-PEG4-EDBp([18F]-EDBp), and [177Lu]-DOTA-PEG4-EDBp ([177Lu]-EDBp), for the surgical navigation, radionuclide imaging, and therapy of TC. METHODS: Based on the previously identified EDB-FN targeted peptide ZD2, the optimized EDB-FN targeted peptide EDBp was identified by using the alanine scan strategy. Three EDBp-based probes, Cy5-EDBp, [18F]-EDBp, and [177Lu]-EDBp, were developed for fluorescence imaging, positron emission tomography (PET) imaging, and radiotherapy in TC tumor-bearing mice, respectively. Additionally, [18F]-EDBp was evaluated in two TC patients. RESULTS: The binding affinity of EDBp to the EDB fragment protein (Kd = 14.4 ± 1.4 nM, n = 3) was approximately 336-fold greater than that of the ZD2 (Kd = 4839.7 ± 361.7 nM, n = 3). Fluorescence imaging with Cy5-EDBp facilitated the complete removal of TC tumors. [18F]-EDBp PET imaging clearly delineated TC tumors, with high tumor uptake (16.43 ± 1.008%ID/g, n = 6, at 1-h postinjection). Radiotherapy with [177Lu]-EDBp inhibited tumor growth and prolonged survival in TC tumor-bearing mice (survival time of different treatment groups: saline vs. EDBp vs. ABRAXANE vs. [177Lu]-EDBp = 8.00 d vs. 8.00 d vs. 11.67 d vs. 22.33 d, ***p < 0.001). Importantly, the first-in-human evaluation of [18F]-EDBp demonstrated that it had specific targeting properties (SUVmax value of 3.6) and safety. CONCLUSION: Cy5-EDBp, [18F]-EDBp, and [177Lu]-EDBp are promising candidates for the surgical navigation, radionuclide imaging, and radionuclide therapy of TC, respectively.

Integrin α6 Targeted Near Infrared Fluorescent Imaging and Photoacoustic Imaging of Hepatocellular Carcinoma in Mice.

Background and Aims: Hepatocellular carcinoma (HCC) is the fourth most common cause of cancer-related death and ranks sixth in terms of incident cases worldwide. The purpose of this study was to develop an effective and sensitive method to distinguish liver cancer tissues from normal tissues in HCC patients. Integrin α6 is a promising cell surface target for molecular imaging of HCC, where it is overexpressed and is a prognostic biomarker. We previously identified an integrin α6-targeted peptide CRWYDENAC (RWY) that has been used for positron emission tomography (PET) imaging of HCC in mouse models. Methods: We labeled the integrin α6-targeted RWY peptide with cyanine 7 (Cy7) to form an optical probe (Cy7-RWY) for near infrared fluorescent (NIRF) and photoacoustic (PA) imaging in HCC. Mice transplanted with subcutaneous HCC-LM3 or orthotopic HCC-H22 cells that overexpressed integrin α6 were intravenously injected with Cy7-RWY and its corresponding Cy7-control. NIRF and PA images of mice were collected from 0 to 48 h after injection. Results: Both NIRF and PA signals started to accumulate in the tumor 2 h after injection of Cy7-RWY and peaked at 24 h. Conclusions: Cy7-RWY is a promising optical probe for NIRF and PA imaging of HCC in mice, and has potential clinical application for HCC detection.

Integrin α6-Targeted Molecular Imaging of Central Nervous System Leukemia in Mice.

Central nervous system leukemia (CNS-L) is caused by leukemic cells infiltrating into the meninges or brain parenchyma and remains the main reason for disease relapse. Currently, it is hard to detect CNS-L accurately by clinically available imaging models due to the relatively low amount of tumor cells, confined blood supply, and the inferior glucose metabolism intensity. Recently, integrin α6-laminin interactions have been identified to mediate CNS-L, which suggests that integrin α6 may be a promising molecular imaging target for the detection of CNS-L. The acute lymphoblastic leukemia (ALL) cell line NALM6 stabled and transfected with luciferase was used to establish the CNS-L mouse model. CNS-L-bearing mice were monitored and confirmed by bioluminescence imaging. Three of our previously developed integrin α6-targeted peptide-based molecular imaging agents, Cy5-S5 for near-infrared fluorescence (NIRF), Gd-S5 for magnetic resonance (MR), and 18F-S5 for positron emission tomography (PET) imaging, were employed for the molecular imaging of these CNS-L-bearing mice. Bioluminescence imaging showed a local intensive signal in the heads among CNS-L-bearing mice; meanwhile, Cy5-S5/NIRF imaging produced intensive fluorescence intensity in the same head regions. Moreover, Gd-S5/MR imaging generated superior MR signal enhancement at the site of meninges, which were located between the skull bone and brain parenchyma. Comparatively, MR imaging with the clinically available MR enhancer Gd-DTPA did not produce the distinguishable MR signal in the same head regions. Additionally, 18F-S5/PET imaging also generated focal radio-concentration at the same head regions, which generated nearly 5-times tumor-to-background ratio compared to the clinically available PET radiotracer 18F-FDG. Finally, pathological examination identified layer-displayed leukemic cells in the superficial part of the brain parenchyma tissue, and immunohistochemical staining confirmed the overexpression of the integrin α6 within the lesion. These findings suggest the potential application of these integrin α6-targeted molecular imaging agents for the accurate detection of CNS-L.

Development of a Radiotracer for PET Imaging of the SNAP Tag.

Cell therapies have progressed to cures for hematopoietic disorders, neurodegenerative diseases, and cancer. However, only some patients can benefit from cell therapies even with prior screening. Due to the limited clinical methods to monitor the in vivo therapeutic functions of these transferred cells over time, the uncertain prognosis is hard to attenuate. Positron emission tomography (PET) cell tracking can provide comprehensive dynamic and spatial information on the proliferation status and whole-body distribution of the therapeutic cell. In this work, we designed and synthesized the first SNAP-tagged PET radiotracer. SNAP tag is an O 6-alkylguanine-DNA alkyltransferase that can form an irreversible bond with 18F-BG-surface for in vivo cell tracking based on a reporter gene system. 18F-BG-surface was obtained by the F-Al radiolabeling method in 32 ± 7% radiochemical yield and showed a high in vitro stability in mouse serum. SNAP-tagged cells could be selectively targeted by 18F-BG-surface both in vitro (4.81 ± 0.08%AD/106 cell vs 2.26 ± 0.10%AD/106 cell) and in vivo (1.90 ± 0.05 vs 0.55 ± 0.02% ID/g, p < 0.01).

Parallel profiling of antigenicity alteration and immune escape of SARS-CoV-2 Omicron and other variants.

SARS-CoV-2 variants have evolved a variety of critical mutations, leading to antigenicity changes and immune escape. The recent emerging SARS-CoV-2 Omicron variant attracted global attention due to its significant resistance to current antibody therapies and vaccines. Here, we profiled the mutations of Omicron and other various circulating SARS-CoV-2 variants in parallel by computational interface analysis and in vitro experimental assays. We identified critical mutations that lead to antigenicity changes and diminished neutralization efficiency of a panel of 14 antibodies due to diverse molecular mechanisms influencing the antigen-antibody interaction. Our study identified that Omicron exhibited extraordinary potency in immune escape compared to the other variants of concern, and explores the application of computational interface analysis in SARS-CoV-2 mutation surveillance and demonstrates its potential for the early identification of concerning variants, providing preliminary guidance for neutralizing antibody therapy.

Sodium Pump Na + /K + ATPase Subunit α1-Targeted Positron Emission Tomography Imaging of Hepatocellular Carcinoma in Mouse Models.

PURPOSE: Positron emission tomography (PET) imaging was not efficiently used in the early diagnosis of hepatocellular carcinoma (HCC) due to the lack of appropriate tracers. Sodium pump Na + /K + ATPase subunit α1 (NKAα1) emerges to be a potential diagnostic biomarker of HCC. Here, we investigated the feasibility of 18F-ALF-NOTA-S3, a PET tracer based on an NKAα1 peptide, to detect small HCC. PROCEDURES: GEPIA database was searched to obtain the expression characteristics of NKAα1 in HCC and its relationship with the prognosis. PET/CT was performed in orthotopic, diethylnitrosamine (DEN)-induced and genetically engineered HCC mouse models to evaluate the use of 18F-ALF-NOTA-S3 to detect HCC lesions. RESULTS: NKAα1 is overexpressed in early HCC with a high positive rate and may correlate with poor survival. In orthotopic, DEN-induced and genetically engineered HCC mouse models, PET/CT imaging showed a high accumulation of 18F-ALF-NOTA-S3 in the tumor. The tumor-to-liver ratios are 2.56 ± 1.02, 4.41 ± 1.09, and 4.59 ± 0.65, respectively. Upregulated NKAα1 expression in tumors were verified by immunohistochemistry. Furthermore, 18F-ALF-NOTA-S3 has the ability to detect small HCC lesions with diameters of 2-5 mm. CONCLUSIONS: NKAα1 may serve as a suitable diagnostic biomarker for HCC. 18F-ALF-NOTA-S3 shows great potential for PET imaging of HCC.

An Optimized Integrin α6-Targeted Magnetic Resonance Probe for Molecular Imaging of Hepatocellular Carcinoma in Mice.

INTRODUCTION: Integrin α6 is an attractive diagnostic biomarker for molecular imaging of hepatocellular carcinoma (HCC) as it has an extremely high positive rate (approximately 94%) in clinical early-stage HCC. In this study, based on our previously identified integrin α6-targeted peptide, we developed an optimized integrin α6-targeted magnetic resonance (MR) probe dubbed DOTA(Gd)-ANADYWR for MR imaging of HCC in mice. MATERIALS AND METHODS: The longitudinal (R1) relaxivity of DOTA(Gd)-ANADYWR was measured on a 3.0 T MR system . The specific tumor enhancement of the agent was investigated in four distinct mouse models, including subcutaneous, orthotopic, genetically engineered and chemically induced HCC mice. RESULTS: The R1 relaxivity value of DOTA(Gd)-ANADYWR is 5.11 mM-1s-1 at 3.0 T, which is similar to that of the nonspecific clinical agent Gadoteridol. DOTA(Gd)-ANADYWR generated superior enhanced MR signal in HCC lesions and provided complementary enhancement MR signals to the clinically available hepatobiliary MR contrast agent gadoxetate disodium (Gd-EOB-DTPA). Importantly, DOTA(Gd)-ANADYWR could efficiently visualize small HCC lesion (approximately 1 mm) which was hardly detected by the clinical Gd-EOB-DTPA. CONCLUSION: These findings suggest the potential application of this integrin α6-targeted MR probe for the detection of HCC, particularly for small HCC.

Rapid Development of SARS-CoV-2 Spike Protein Receptor-Binding Domain Self-Assembled Nanoparticle Vaccine Candidates.

The coronavirus disease pandemic of 2019 (COVID-19) caused by the novel SARS-CoV-2 coronavirus resulted in economic losses and threatened human health worldwide. The pandemic highlights an urgent need for a stable, easily produced, and effective vaccine. SARS-CoV-2 uses the spike protein receptor-binding domain (RBD) to bind its cognate receptor, angiotensin-converting enzyme 2 (ACE2), and initiate membrane fusion. Thus, the RBD is an ideal target for vaccine development. In this study, we designed three different RBD-conjugated nanoparticle vaccine candidates, namely, RBD-Ferritin (24-mer), RBD-mi3 (60-mer), and RBD-I53-50 (120-mer), via covalent conjugation using the SpyTag-SpyCatcher system. When mice were immunized with the RBD-conjugated nanoparticles (NPs) in conjunction with the AddaVax or Sigma Adjuvant System, the resulting antisera exhibited 8- to 120-fold greater neutralizing activity against both a pseudovirus and the authentic virus than those of mice immunized with monomeric RBD. Most importantly, sera from mice immunized with RBD-conjugated NPs more efficiently blocked the binding of RBD to ACE2 in vitro, further corroborating the promising immunization effect. Additionally, the vaccine has distinct advantages in terms of a relatively simple scale-up and flexible assembly. These results illustrate that the SARS-CoV-2 RBD-conjugated nanoparticles developed in this study are a competitive vaccine candidate and that the carrier nanoparticles could be adopted as a universal platform for a future vaccine development.

Clinical and radiologic features of the first cured Coronavirus disease 2019 (COVID-19) patient in Guangzhou City, China.

To determine changes in clinical and radiologic findings associated with Coronavirus disease 2019 (COVID-19) from diagnosis to recovery, we retrospectively reviewed the diagnosis and treatment records of the first patient cured of COVID-19 in Guangzhou. A 55-year-old woman from Wuhan was admitted to the hospital isolation ward with the chief complaint of "cough for 11 days and once fever 8 days ago" on January 22, 2020. COVID-19 was laboratory confirmed by reverse transcription polymerase chain reaction (RT-PCR) assay, and she received conventional antiviral therapy, such as moxifloxacin, traditional Chinese medicine, and arbidol. Repeat chest-computed tomography (CT) scans were performed on days 13 and 19 of her illness. The former showed radiologic findings, including ground-glass opacities (GGOs), which revealed viral pneumonia; the latter revealed that the previous lesions had been significantly absorbed. The lesions on CT scans were consistent with the changes in the course of disease. Some drugs, such as traditional Chinese medicine and arbidol, might play an important role in the recovery of COVID-19 patients. This study provides some new insights into the formulation of a timely and effective diagnostic and therapeutic strategy to cure patients with COVID-19.

The anti-inflammatory drug dimethyl itaconate protects against colitis-associated colorectal cancer.

Colorectal cancer (CRC) is the third most common diagnosed cancer of which risk factors include unhealthy diet, smoking, and chronic inflammation. Weakening the inflammatory response emerges as an effective therapeutic strategy to prevent the progression of CRC. Inflammatory macrophages produce substantial amounts of immunoregulatory metabolite itaconate, which is synthesized by the immune response gene 1 (Irg1). In this study, we use a membrane-permeable itaconate derivative, dimethyl itaconate (DI), for the protection against CRC in mouse model. DI decreased the high inflammatory state of ulcerative colitis and reduced the colitis-associated cancer (CAC) risk. Mechanistically, DI inhibited the secretion of the cytokines IL-1ß and CCL2 from intestinal epithelial cells, and therefore reduced the recruitment of macrophages into tumor microenvironment. Meanwhile, the decrease of macrophage infiltration was accompanied by a decrease of myeloid-derived suppressor cell (MDSC) infiltration and the differentiation of T cell subsets into cytotoxic T cells. We showed that itaconate derivative limits inflammatory response, indicating a negative feedback loop that involves an inflammatory agent and itaconate. Our findings demonstrate the potential application of DI for the prevention of colitis-associated CRC. KEY MESSAGES: Dimethyl itaconate (DI) suppresses ulcerative colitis and colitis-associated colorectal cancer DI decreases infiltration of macrophages and myeloid-derived suppressor cells into tumor DI weakens the inflammatory response via inhibiting the secretion of IL-1ß and CCL2.

A method to establish a c-Myc transgenic mouse model of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) remains one of the most lethal malignant cancers worldwide. HCC mouse models are widely used to explore the molecular pathogenesis of HCC and to test novel drug candidates. The advantages of this mouse model are as follows:•This method developed a H11LNL-Myc knock-in HCC mouse model by crossing H11LNL-Myc heterozygous mice with (albumin (Alb))-cre transgenic mice to generate c-Myc/Alb-cre double positive mice.•The c-Myc/Alb-cre double-positive mice exhibited a typical HCC phenotype, and showed accelerated tumor initiation and rapid HCC progression. Early stage HCC tumors (2-3 mm in diameter) were observed in male mice at the age of 47 days and in female mice at the age of 60 days.•Approximately 3 months later, the HCC tumors had progressed to a late stage (> 1 cm in diameter), and 100% of the male and female mice had HCC.

Transferrin receptor 1 targeted optical imaging for identifying glioma margin in mouse models.

OBJECTIVE: Optical molecular imaging technology that indiscriminately detects intracranial glioblastoma (GBM) can help neurosurgeons effectively remove tumor masses. Transferrin receptor 1 (TfR 1) is a diagnostic and therapeutic target in GBM. A TfR 1-targeted peptide, CRTIGPSVC (CRT), was shown to cross the blood brain barrier (BBB) and accumulate at high levels in GBM tissues. In this study, we synthesized a TfR 1-targeted near-infrared fluorescent (NIRF) probe, Cy5-CRT, for identifying the GBM tissue margin in mouse models. METHODS: We initially confirmed the overexpression of TfR 1 in GBM and the tumor-specific homing ability of Cy5-CRT in subcutaneous and orthotopic GBM mouse models. We then examined the feasibility of Cy5-CRT for identifying the tumor margin in orthotopic GBM xenografts. Finally, we compared Cy5-CRT with the clinically used fluorescein sodium in identifying tumor margins. RESULTS: Cy5-CRT specifically accumulated in GBM tissues and detected the tumor burden with exceptional contrast in mice with orthotopic GBM, enabling fluorescence-guided GBM resection under NIRF live imaging conditions. Importantly, Cy5-CRT recognized the GBM tissue margin more clearly than fluorescein sodium. CONCLUSIONS: The TfR 1-targeted optical probe Cy5-CRT specifically differentiates tumor tissues from the surrounding normal brain with high sensitivity, indicating its potential application for the precise surgical removal of GBM.

Integrin α6-Targeted Magnetic Resonance Imaging of Hepatocellular Carcinoma in Mice.

PURPOSE: Magnetic resonance imaging (MRI) has a high spatial resolution for detecting hepatocellular carcinoma (HCC). Integrin α6 has emerged as a diagnostic and prognostic biomarker of HCC. Here, we developed the MR contrast agent RWY-dL-(Gd-DOTA)4 based on the integrin α6-targeted RWY peptide that we previously identified to detect HCC. PROCEDURES: Contrast-enhanced MRI was carried out to evaluate the use of RWY-dL-(Gd-DOTA)4 to detect HCC lesions in subcutaneous and diethylnitrosamine (DEN)-induced HCC mouse models. RESULTS: Enhancement MR signals were observed in HCC-LM3 subcutaneous liver tumors in the first 5 min post-injection of RWY-dL-(Gd-DOTA)4 at a low dose of 0.03 mmol Gd/kg. Moreover, RWY-dL-(Gd-DOTA)4 generated superior contrast enhancement for liver tumors in chemical-induced HCC mice. Importantly, RWY-dL-(Gd-DOTA)4 provided complementary enhancement MR signals to the clinical available hepatobiliary MR contrast agent gadoxetate disodium Gd-EOB-DTPA. Additionally, RWY-dL-(Gd-DOTA)4 showed minimal gadolinium retention in normal tissues and organs at 48 h post-injection. CONCLUSION: These findings potentiate the use of RWY-dL-(Gd-DOTA)4 for the MRI of HCC to improve the diagnosis of HCC.

Integrin α6-Targeted Positron Emission Tomography Imaging of Colorectal Cancer.

Colorectal cancer (CRC) is the third most common cancer and the fourth leading cause of cancer deaths worldwide. Integrin α6 is overexpressed in all stages of CRC which makes it a potential diagnostic biomarker for CRC. Previously, we identified an integrin α6-targeted peptide CRWYDENAC (dubbed RWY) using phage display technology and employed it for nasopharyngeal carcinoma specific nanotherapeutics. In this study, we developed a radiotracer, 18F-RWY, based on this integrin α6-targeted RWY peptide for positron emission tomography (PET) imaging of CRC. Integrin α6 was overexpressed on several CRC cells including HT29 cells where the biotin-labeled RWY peptide colocalized with integrin α6. 18F-RWY PET imaging was performed on subcutaneous, chemically induced, and genetically engineered CRC mice. 18F-RWY generated high PET signals in subcutaneous HT29 tumors, and the tumor uptake of 18F-RWY was reduced by a blocking study using nonradio-labeled RWY. Moreover, 18F-RWY PET imaging enabled detection of CRC in chemically induced and genetically engineered CRC mice. The overexpression of integrin α6 in tumor tissues isolated from chemically induced and genetically engineered CRC mice was confirmed. These results demonstrate the potential clinical application of 18F-RWY for PET imaging of CRC.