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Currently, the 5-year survival rate for patients with advanced hepatocellular carcinoma (HCC) is very low. Therefore, there is an urgent need to find new strategies for the treatment of HCC. TMTP1 (NVVRQ) is a tumor-homing peptide that has been shown to target a range of highly metastatic tumor cells. In this study, a novel radiotherapeutic probe, [

Immune checkpoint blockers (ICBs) targeting programmed death receptor 1 (PD-1) ligand 1 (PD-L1) for immunotherapy have radically reformed oncology. It is of great significance to enhance the response rate of ICB in cancer patients. Here, a radioiodinated anti-PD-L1 antibody (

Supplementary Data from A Paradigm of Cancer Immunotherapy Based on 2-[18F]FDG and Anti–PD-L1 mAb Combination to Enhance the Antitumor Effect

Purpose:Efforts have been devoted to select eligible candidates for PD-1/PD-L1 immune checkpoint blocker (ICB) immunotherapy. Here, we have a serendipitous finding of positron emission tomography (PET) imaging tracer 2-[18F]FDG as a potential immunomodulator. Therefore, we hypothesize that 2-[18F]FDG could induce PD-L1 expression change and create an immune-favorable microenvironment for tumor immunotherapy.Experimental Design:We designed a series of assays to verify PD-L1 upregulation, and tested immunotherapy regimens based on 2-[18F]FDG and anti–PD-L1 mAb, as monotherapy and in combination, in fully immunocompetent mice of MC38 and CT26 models. PD-L1 expression and tumor microenvironment (TME) changes were analyzed by Western blot, transcriptomics study, and flow-cytometric analysis.Results:PD-L1 was upregulated in a time- and dose-dependent manner after being induced by 2-[18F]FDG. The activation of NF-κB/IRF3 pathway and STAT1/3-IRF1 pathway play crucial parts in modulating PD-L1 expression after DNA damage and repair. Improved αPD-L1 mAb utilization rate and significant tumor growth delay were observed when the personalized therapeutic alliance of 2-[18F]FDG stimulation and ICB was used. In addition, combination of 2-[18F]FDG with αPD-L1 mAb could reprogram a TME from “cold” to “hot,” to make low immunoactivity tumors sensitive to ICB therapy.Conclusions:In summary, this promising paradigm has the potential to expand the traditional tumor theranostics. 2-[18F]FDG-based ICB immunotherapy is highly significant in enhancing antitumor effect. A research of 2-[18F]FDG-based ICB immunotherapy has been proposed to enhance the antitumor effect.

Overexpression of estrogen receptors (ERs) is one of the important characteristics of most breast cancers. We aim to develop a new type of ER-specific radioiodine-labeled estrogen derivative ([131I]IPBA-EE), which was modified with an albumin-specific ligand 4-(p-iodophenyl) butyric acid (IPBA) to improve the metabolic stability and enhance the ER-targeting ability of estrogen. [131I]IPBA-EE can effectively bind to albumin in vitro, and its dissociation constant (Kd = 0.31 μM) is similar to IPBA (Kd = 0.30 μM). The uptake of [131I]IPBA-EE in ER-positive MCF-7 cells (41.81 ± 3.41%) was significantly higher than that in ER-negative MDA-MB-231 cells (8.78 ± 2.37%, ***P < 0.0005) and could be significantly blocked (3.92 ± 0.35%, ***P < 0.0005). The uptakes of [131I]IPBA-EE in rat uterus and ovaries were 5.66 ± 0.34% ID/g and 5.71 ± 2.77% ID/g, respectively, at 1 h p.i., and these uptakes could be blocked by estradiol (uterus: 2.81 ± 0.41% ID/g, *P < 0.05; ovarian: 3.02 ± 0.08% ID/g, *P < 0.05). SPECT/CT imaging showed that ER-positive MCF-7 tumor uptake of [131I]IPBA-EE reached to 6.07 ± 0.20% ID/g at 7 h p.i., which was significantly higher than that of ER-negative MDA-MB-231 tumor (0.87 ± 0.08% ID/g, **P < 0.005) and could be blocked obviously with fulvestrant (1.65 ± 1.56% ID/g, *P < 0.05). In conclusion, a novel radioiodinated estradiol derivative, [131I]IPBA-EE with albumin-binding property and good metabolic stability, was developed to image the ER in breast cancer. This promising ER-targeted probe has the potential to warrant further preclinical investigations.

Intravascular brachytherapy requires advances in radio-embolization technologies that combine brilliant radiostability efficacy with a facile and green synthesis route. We report a hybrid-integrated radioactive microsphere strategy using phosphorylcholine-modified lutetium-177 coordinated polymeric microspheres (177Lu-PCMs) that were fabricated via radiation-induced graft polymerization for imaging-guided locoregional intravascular brachytherapy. The underlying formation mechanism of 177Lu-PCMs is elucidated using first-principles computations and density functional theory calculations and 177Lu loading mechanisms was investigated with Near-edge and extended X-ray absorption fine structure spectroscopy. The engineered 177Lu-PCMs exhibit excellent mechanical properties, good hydrophilicity, and controlled sphere diameter. These features provide advantages of ultra-stable and ultra-selective embolic radio-theranostics, which is demonstrated in different preclinical rodent models and isolated human liver tumor tissues. During locoregional intra-arterial brachytherapy, 177Lu-PCMs can be visualized via SPECT to validate the in vivo biodistribution and retention in real time, achieving precise delivery, effective anti-cancer treatment, and a distinguished safety profile without degradation, ectopic embolization, and adverse reactions. Therefore, this study may offer a new avenue for the development of a highly innovative and translational approach for precision intravascular brachytherapy.

Although KRAS has been an important target for many cancers, direct inhibition of oncogenic RAS remains challenging. Until recently, covalent KRAS G12C-specific inhibitors have been developed and progressed to the clinics. Nevertheless, not all patients benefit from these covalent inhibitors. At present, identification of candidates for this treatment requires tissue biopsies and gene sequencing, which are invasive, time-consuming, and could be of insufficient quality and limited predictive value owing to tumor heterogeneity. The use of noninvasive molecular imaging techniques such as PET and SPECT for spying KRAS G12C mutation in tumors provide a promising strategy for circumventing these hurdles. In the present study, based on the covalent G12C-specific inhibitor ARS-1620, we sought to develop radiolabeled small molecules for direct imaging of the KRAS mutation status in tumors. [131I]I-ARS-1620 and [18F]F-ARS-1620 were successfully prepared with high radiochemical yield, radiochemical purity, and molar activity. In vitro and in vivo studies have demonstrated the affinity, specificity, and capacity of [131I]I-ARS-1620 for direct imaging of the oncogenic KRAS G12C mutant. This initial attempt allows us to directly screen the KRAS G12C mutant for the first time in vivo.

The formation of advanced plaques, which is characterized by the uninterrupted aggregation of macrophages with high expression of folate receptor-β (FR-β), is observed in several concomitant metabolic syndromes. The objective of this study was to develop a novel FR-β-targeted single-photon emission computed tomography (SPECT) radiotracer and validate its application to the noninvasive detection of atherosclerosis (AS) plaque and non-alcoholic fatty liver (NAFL). Two radioiodinated probes, [131I]IPBF and [131I]IBF, were developed, and cell uptake studies were used to identify their specific targets for activated macrophages. Biodistribution in normal mice was performed to obtain the pharmacokinetic information of the probes. Apolipoprotein E knockout (ApoE−/−) mice with atherosclerotic aortas were induced by a high-fat and high-cholesterol (HFHC) diet. To investigate the affinity of radiotracers to FR-β, Kd values were determined using in vitro assays. In addition, the assessments of the aorta in the ApoE−/− mice at different stages were performed using in vivo SPECT/CT imaging, and the findings were compared by histology. Both [131I]IPBF and [131I]IBF were synthesized with > 95% radiochemical purity and up to 3 MBq/nmol molar activity. In vitro assay of [131I]IPBF showed a moderate binding affinity to plasma proteins and specific uptake in activated macrophages. The prolonged blood elimination half-life (t1/2z) of [131I]IPBF (8.14 h) was observed in a pharmacokinetic study of normal mice, which was significantly longer than that of [131I]IBF (t1/2z = 2.95 h). As expected, the Kd values of [131I]IPBF and [131I]IBF in the Raw 264.7 cells were 43.94 ± 9.83 nM and 61.69 ± 15.19 nM, respectively. SPECT imaging with [131I]IPBF showed a high uptake in advanced plaques and NAFL. Radioactivity in excised aortas examined by ex vivo autoradiography further confirmed the specific uptake of [131I]IPBF in high-risk AS plaques. In summary, we reported a proof-of-concept study of an albumin-binding folate derivative for macrophage imaging. The FR-β-targeted probe, [131I]IPBF, significantly prolongs the plasma elimination half-life and has the potential for the monitoring of AS plaques and concomitant fatty liver.

Breast cancer is the most common cancer in women worldwide. Due to the heterogeneous nature of breast cancer, the optimal treatment and expected response for each patient may not necessarily be universal. Molecular imaging techniques could play an important role in the early detection and targeted therapy evaluation of breast cancer. This review focuses on the development of peptides labeled with SPECT and PET radionuclides for breast cancer imaging. We summarized the current status of radiolabeled peptides for different receptors in breast cancer. The characteristics of radionuclides and major techniques for peptide labeling are also briefly discussed.

Purpose: Efforts have been devoted to select eligible candidates for PD-1/PD-L1 immune checkpoint blocker (ICB) immunotherapy. Here, we have a serendipitous finding of positron emission tomography (PET) imaging tracer 2-[18F]FDG as a potential immunomodulator. Therefore, we hypothesize that 2-[18F]FDG could induce PD-L1 expression change and create an immune-favorable microenvironment for tumor immunotherapy. Experimental Design: We designed a series of assays to verify PD-L1 upregulation, and tested immunotherapy regimens based on 2-[18F]FDG and anti–PD-L1 mAb, as monotherapy and in combination, in fully immunocompetent mice of MC38 and CT26 models. PD-L1 expression and tumor microenvironment (TME) changes were analyzed by Western blot, transcriptomics study, and flow-cytometric analysis. Results: PD-L1 was upregulated in a time- and dose-dependent manner after being induced by 2-[18F]FDG. The activation of NF-κB/IRF3 pathway and STAT1/3-IRF1 pathway play crucial parts in modulating PD-L1 expression after DNA damage and repair. Improved αPD-L1 mAb utilization rate and significant tumor growth delay were observed when the personalized therapeutic alliance of 2-[18F]FDG stimulation and ICB was used. In addition, combination of 2-[18F]FDG with αPD-L1 mAb could reprogram a TME from “cold” to “hot,” to make low immunoactivity tumors sensitive to ICB therapy. Conclusions: In summary, this promising paradigm has the potential to expand the traditional tumor theranostics. 2-[18F]FDG-based ICB immunotherapy is highly significant in enhancing antitumor effect. A research of 2-[18F]FDG-based ICB immunotherapy has been proposed to enhance the antitumor effect.

Purpose: Tumor Necrosis Factor Receptor 1 (TNFR1) and integrin αvβ3 receptor are overexpressed in breast cancer. We hypothesized that a peptide ligand recognizing both receptors in a single receptor-binding probe would be advantageous. Here, we developed a novel 18F-labeled fusion peptide probe [18F]-NOTA-Gly3- E(2PEG4-RGD-WH701) targeting dual receptors (TNFR1 and αvβ3) and evaluated the diagnostic efficacy of this radioactive probe in both MDA-MB-231 and MCF-7 xenograft models in mice. Methods: The NOTA-conjugated RGD-WH701 analog was radiolabeled with 18F using NOTA-AlF chelation method. We used two PEG4 molecules and Glutamic acid (Glu) to covalently link c(RGDyK) with WH701. Gly3 was also added to further improve the water solubility and pharmacokinetic properties of the probe. The expression of TNFR1 and Integrin αvβ3 in MCF-7 and MDA-MB-231 cells was detected by western blot analysis and immunofluorescence staining. The tumor-targeting characteristics of [18F]-NOTA-Gly3-E(2PEG4-RGDWH701) were assessed in nude mice bearing MDA-MB-231 and MCF-7 xenografts. Results: HPLC analysis of the product NOTA-G3-E (2P4-RGD-WH701) revealed a purity >95%. The yield after attenuation correction was approximately 33.5%±2.8% (n=5), and the radiochemical purity was above 95%. The MDA-MB-231 tumor uptake of [18]-NOTA-Gly3-E(2PEG4-RGD-WH701) was 1.14±0.14%ID/g, as measured by PET at 40min postinjection (p.i.). In comparison, the tumor uptake of [18F]-NOTA-RGD and [18F]- NOTA-WH701 in MDA-MB-231 xenografts was 0.96±0.13%ID/g and 0.93±0.28%ID/g, respectively. The MCF-7 tumor uptake of [18F]-NOTA-Gly3-E(2PEG4-RGD-WH701) was 1.22±0.11%ID/g, as measured by PET at 40min postinjection (p.i.). In comparison, the tumor uptake of [18F]-NOTA-RGD and [18F]-NOTA-WH701 in MCF-7 xenografts was 0.99±0.18%ID/g and 0.57±0.08%ID/g, respectively. Conclusion: [18F]AlF-NOTA-Gly3-E(2PEG4-RGD-WH701) was successfully synthesized and labeled with 18F. The results from the microPET/CT and biodistribution studies of [18F]AlF-NOTA-Gly3-E(2PEG4-RGDWH701) showed that the tracer could specifically target TNFR1 and integrin αvβ3 receptors.

Glypican-3 (GPC3) is a diagnostic biomarker for hepatocellular carcinoma (HCC). Although numerous designs targeting GPC3 have been reported, the HCC diagnostic agents with specific tumor accumulation and low background, particularly in normal liver tissue, are still in need. Peptides have attracted considerable attention as an imaging probe due to their low immunogenicity, short in vivo circulation time, and acceptable production cost. Herein, a two-step phage display screening approach was performed against GPC3-high expression tumor xenografts in vivo, followed by human recombinant GPC3 protein in vitro. A GPC3-specific binding peptide, named TJ12P2, with the sequence of Ser-Asn-Asp-Arg-Pro-Pro-Asn-Ile-Leu-Gln-Lys-Arg (SNDRPPNILQKR) was identified. The apparent Kd value between TJ12P2 and the GPC3 protein was measured as 158.2 ± 26.25 nM. After 18F labeling, 18F-AlF-NOTA-TJ12P2 was found accumulated in the tumors by positron emission tomography (PET) imaging in two HCC subcutaneous tumor models (HepG2 and SMMC-7721) with high GPC3 expression. Static PET imaging revealed that 18F-AlF-NOTA-TJ12P2 accumulation in the HepG2 and SMMC-7721 tumors reached 1.825 ± 0.296 %ID g-1 and 1.575 ± 0.520 %ID g-1, with tumor-to-muscle ratios of 4.14 ± 0.50 and 4.25 ± 0.25, respectively, at 30 min post-injection (p.i.). Much less accumulation (0.533 ± 0.078 %ID g-1) of the 18F-AlF-NOTA-TJ12P2 was found in the control PC3 tumors with low GPC3 expression. More importantly, no obvious normal liver uptake of TJ12P2 was observed in the abovementioned animal models. As a result, a novel peptide targeting GPC3, TJ12P2, with strong affinity and specificity was identified using a two-step phage display screening technique in the present study. The 18F-AlF-NOTA-TJ12P2 may be a promising PET imaging probe with translational potential for accurate HCC diagnosis.

[Image: see text] Two novel PEGylated ethinylestradiol (PEG = poly(ethylene glycol)) estrogen receptor (ER) targeting probes [(131)I]EITE and [(131)I]MITE were synthesized and evaluated. Both probes had a nanomolar binding affinity to the ER receptor (36.47 nM for [(131)I]EITE and 61.83 nM for [(131)I]MITE). They showed high uptake in ER-positive MCF-7 cells and tumors, which could be significantly blocked by a coinjection of excess estradiol. Their ER specificities were further demonstrated by the low uptake in ER-negative MDA-MB-231 cells and tumors. The maximum tumor-to-muscle (T/M) ratios reach to 6.59 for [(131)I]EITE at 1 h postinjection (p.i.) and to 3.69 for [(131)I]MITE at 2 h p.i. in MCF-7 tumors. Among these two probes, [(131)I]EITE showed a faster tumor accumulation and a higher T/M ratio indicating it could be a better candidate for the potential diagnosis of ER-positive breast cancers.

Overexpression of estrogen receptors (ERs) is one of the important characteristics of most breast cancers. We aim to develop a new type of ER-specific radioiodine-labeled estrogen derivative ([

Background: Neuropilin-1 (NRP-1) and integrin αvβ3 receptors are both overexpressed in breast cancer. Methods: We developed and synthesized a heterodimeric tracer consisting of Arg−Gly−Asp (RGD) and Ala-Thr-Trp-Leu-Pro-Pro-Arg (ATWLPPR) peptides that simultaneously targets integrin αvβ3 and NRP-1. We then investigated the diagnostic efficacy of RGD-ATWLPPR heterodimeric peptides in MCF-7 xenograft models in mice. DOTA-conjugated RGD-ATWLPPR peptides were then radiolabeled with 68Ga, and the receptor-binding characteristics and tumor-targeting efficacy of 68Ga-DOTA-RGD-ATWLPPR were investigated in vitro and in vivo. We also detected integrin αvβ3 and NRP-1 expression in MCF-7 cells and tumor tissues. Results: The peptide showed high stability in vitro. Static PET/CT imaging studies showed that MCF-7 tumors were clearly visible 30 min and 60 min after 68Ga-DOTA-RGD-ATWLPPR injection. Further, the heterodimer showed higher tumor uptake than 68Ga-DOTA-RGD or 68Ga-DOTA-ATWLPPR alone. High specificity was shown in blocking studies using RGD and ATWLPPR peptides. MicroPET/CT and biodistribution studies using 68Ga-DOTA-RGD-ATWLPPR showed that the tracer specifically targets NRP-1 and integrin ανβ3 receptors. Conclusions: Compared with 68Ga-DOTA-RGD and 68Ga-DOTA-ATWLPPR, 68Ga-DOTA-RGD-ATWLPPR has higher binding affinity, better targeting efficiency, and longer tumor retention time. It therefore has potential as an imaging probe for breast cancer detection.

Efforts have been devoted to select eligible candidates for PD-1/PD-L1 immune checkpoint blocker (ICB) immunotherapy based on radiopharmaceuticals. Here, we have observed a tracking-to-triggering (referred to as “T2T”) immunoediting effect of the employed radionuclides. In particular, we found the usefulness of 2-[18F]FDG in cancer ICB therapy. Given that the PD-L1 expression is upregulated after the administration of various radiotracers, the predictive result from PET/SPECT imaging should be treated with caution. Viewed positively, radiotracers are potential immunomodulators to create an immune-favorable microenvironment for tumor immunotherapy. Improving αPD-L1 mAb utilization and significant tumor growth delay are observed when the personalized therapeutic alliance of radiotracer stimulation and ICB are employed. This new paradigm has the potential to expand the traditional tumor theranostic model and implement precision cancer immunotherapy.

Glypican-3 (GPC3) is a diagnostic biomarker for hepatocellular carcinoma (HCC). Although numerous designs targeting GPC3 have been reported, the HCC diagnostic agents with specific tumor accumulation and low background, particularly in normal liver tissue, are still in need. Peptides have attracted considerable attention as an imaging probe due to their low immunogenicity, short in vivo circulation time, and acceptable production cost. Herein, a two-step phage display screening approach was performed against GPC3-high expression tumor xenografts in vivo, followed by human recombinant GPC3 protein in vitro. A GPC3-specific binding peptide, named TJ12P2, with the sequence of Ser-Asn-Asp-Arg-Pro-Pro-Asn-Ile-Leu-Gln-Lys-Arg (SNDRPPNILQKR) was identified. The apparent Kd value between TJ12P2 and the GPC3 protein was measured as 158.2 ± 26.25 nM. After 18F labeling, 18F-AlF-NOTA-TJ12P2 was found accumulated in the tumors by positron emission tomography (PET) imaging in two HCC subcutaneous tumor models (HepG2 and SMMC-7721) with high GPC3 expression. Static PET imaging revealed that 18F-AlF-NOTA-TJ12P2 accumulation in the HepG2 and SMMC-7721 tumors reached 1.825 ± 0.296 %ID g-1 and 1.575 ± 0.520 %ID g-1, with tumor-to-muscle ratios of 4.14 ± 0.50 and 4.25 ± 0.25, respectively, at 30 min post-injection (p.i.). Much less accumulation (0.533 ± 0.078 %ID g-1) of the 18F-AlF-NOTA-TJ12P2 was found in the control PC3 tumors with low GPC3 expression. More importantly, no obvious normal liver uptake of TJ12P2 was observed in the abovementioned animal models. As a result, a novel peptide targeting GPC3, TJ12P2, with strong affinity and specificity was identified using a two-step phage display screening technique in the present study. The 18F-AlF-NOTA-TJ12P2 may be a promising PET imaging probe with translational potential for accurate HCC diagnosis.

PURPOSE: The small peptide TMTP1 (NVVRQ) has been proved to target a series of highly metastatic tumor cells. The aim of this study was to develop a new agent based on TMTP1 conjugated with Evans blue (EB), to increase tumor uptake and modify the pharmacokinetic characteristics of the resulting radiolabeled agent. PROCEDURES: DOTA-EB-TMTP1 was prepared through conventional solid-phase peptide synthesis chemistry. Then, it was successfully labeled with Cu-64 to obtain [(64)Cu]DOTA-EB-TMTP1. The tumor targeting properties were evaluated in vivo using 143B xenografts. RESULTS: DOTA-EB-TMTP1 was successfully labeled with Cu-64 in a yield of 87.3 ± 5.2 %. In a small animal positron emission tomography/X-ray computed tomography (PET/CT) study in osteosarcoma 143B xenograft mice, [(64)Cu]DOTA-EB-TMTP1 was found to rapidly accumulate in the tumor tissue. The tumor uptake increased over time and reached a plateau of 6.50 ± 0.88 % ID/g 8 h after tail vein injection. The radioactivity remained in the tumor tissue 48 h postinjection with a negligible decrease. CONCLUSIONS: Overall, the introduction of the EB motif to TMTP1 significantly changed its pharmacokinetics in vivo, and this strategy fulfills the purpose of prolonging the blood circulation and enhancing the tumor uptake. [(64)Cu]DOTA-EB-TMTP1 is a promising agent for osteosarcoma targeting. Moreover, our study highlights that DOTA-EB-TMTP1 is a good candidate for labeling with different radionuclides for potential theranostic applications.

Tumor necrosis factor receptor 1 (TNFR1) is overexpressed in several varieties of carcinoma, including breast cancer. WH701 (Ala-Thr-Ala-Gln-Ser-Ala-Tyr-Gly), which was identified by phage display, can specifically bind to TNFR1. In this study, we labeled WH701 with 18F and investigated its tumor diagnostic value. WH701 was synthesized by standard Fmoc-solid phase synthetic protocols and conjugated by NOTA–NHS. NOTA–WH701 was radiolabeled with 18F using NOTA–AlF chelation reaction. The tumor target properties were evaluated in vitro and in vivo using MCF-7 xenografts and inflammation models. [18F]AlF–NOTA–WH701 was labeled in 25 min with a decay-corrected yield of 38.1 ± 4.8% (n = 5) and a specific activity of 10.4–13.0 GBq/μmol. WH701 had relatively high affinity for MCF-7 cells in vitro and [18F]AlF–NOTA–WH701 displayed relatively high tumor uptake in vivo. The tumor to muscle ratio was 4.25 ± 0.56 at 30 min post-injection (p.i.); further, there was a significant difference between the tumor/muscle and inflammation/muscle (3.22 ± 0.56) ratio, which could differentiate the tumor and inflammation. The tumor uptake of [18F]AlF–NOTA–WH701 could be inhibited by 71.1% by unlabeled WH701 at 30 min p.i. We have developed a promising PET tracer [18F]AlF–NOTA–WH701 for the noninvasive detection of breast cancer in vivo.

Photodynamic therapy (PDT) is a novel treatment modality that is under intensive preclinical investigations for a variety of diseases, including cancer. Despite extensive studies in this area, selective and effective photodynamic agents that can specifically accumulate in tumors to reach a therapeutic concentration are limited. Although recent attempts have produced photosensitizers (PSs) complexed with various nanomaterials, the tedious preparation steps and poor tumor efficiency of therapy hamper their utilization. Here, we developed a CD44-targeted nanophotodynamic agent by physically encapsulating a photosensitizer, Ce6, into a hyaluronic acid nanoparticle (HANP), which was hereby denoted HANP/Ce6. Its physical features and capability for photodynamic therapy were characterized in vitro and in vivo. Systemic delivery of HANP/Ce6 resulted in its accumulation in a human colon cancer xenograft model. The tumor/muscle ratio reached 3.47 ± 0.46 at 4 h post injection, as confirmed by fluorescence imaging. Tumor growth after HANP/Ce6 treatment with laser irradiation (0.15 W/cm

Fluorinated polyethylenimine derivative labeled with radionuclide (99m) Tc is developed as a (19) F MRI/SPECT/PA multifunctional imaging agent with good asialoglycoprotein receptors (ASGPR)-targeting ability. This multifunctional agent is safe and suitable for (19) F MRI/SPECT/PA imaging and has the potential to detect hepatic diseases and to assess liver function, which provide powerful support for the development of personalized and precision medicine.

The goal of this study is to evaluate a new (18) F-labeled imaging agent for diagnosing high metastatic (aggressive) hepatocellular carcinoma using positron emission tomography (PET). The new (18) F-labeled imaging agent [(18) F]AlF-NOTA-G-TMTP1 was synthesized and radiolabeled with (18) F using NOTA-AlF chelation method. The tumor-targeting characteristics of [(18) F]AlF-NOTA-G-TMTP1 was assessed in HepG2, SMCC-7721, HCC97L and HCCLM3 xenografts. The total synthesis time was about 20 min with radiochemical yield of 25 ± 6%. The specific activity was about 11.1-14.8 GBq/µmol at the end of synthesis based on the amount of peptide used and the amount of radioactivity trapped on the C18 column. The log P value of [(18) F]AlF-NOTA-G-TMTP1 was -3.166 ± 0.022. [(18) F]AlF-NOTA-G-TMTP1 accumulated in SMCC-7721 and HCCLM3 tumors (high metastatic potential) in vivo and result in tumor/muscle (T/M) ratios of 4.5 ± 0.3 and 4.7 ± 0.2 (n = 4) as measured by PET at 40 min post-injection (p.i.). Meanwhile, the tumor/muscle (T/M) ratios of HepG2 and HCC97L tumors (low metastatic potential) were1.6 ± 0.3 and 1.8 ± 0.4. The tumor uptake of [(18) F]AlF-NOTA-G-TMTP1 could be inhibited 61.9% and 57.6% by unlabeled G-TMTP1 in SMCC-7721 and HCCLM3 xenografts at 40 min p.i., respectively. Furthermore, [(18) F]AlF-NOTA-G-TMTP1 showed pretty low activity in the liver and intestines in all tumor bearing mice, such in vivo distribution pattern would be advantageous for the detection of hepatic carcinoma. Overall, [(18) F]AlF-NOTA-G-TMTP1 may specifically target high metastatic or/and aggressive hepatocellular carcinoma with low background activity and, therefore, holds the potential to be used as an imaging agent for detecting tumor lesions within the liver area. Copyright © 2016 John Wiley & Sons, Ltd.

Synthetic oligodeoxynucleotides (ODN) containing unmethylated CpG motifs were found to be able to target cells that express Toll-like receptor 9 to modulate innate and adaptive immune reactions. But their in vivo application in immunotherapy against cancer has not been successful. We attempted in this study to examine polyethylene-glycol (PEG) conjugated CpG ODNs and investigated their mechanism of immune modulation in anti-cancer therapy. CpG-PEG conjugates with different PEG lengths were synthesized. In vitro activity as well as in vivo pharmacokinetics and pharmacodynamics properties were evaluated. CpG-PEG20Ks were found to be able to persist longer in circulation and activate various downstream effector cells. After intravenous injection, they resulted in higher levels of IL-12p70 in the circulation and lower M-MDSC infiltrates in the tumor microenvironment. Such activities were different from those of CpG ODNs without PEGylation, suggesting different PK-PD profiles systemically and locally. Our data support the development of CpG-PEGs as a new therapeutic agent that can be systemically administered to modulate immune responses and the microenvironment in tumor tissues.

Nanotransducer-mediated photothermal therapy (PTT) has emerged as an attractive therapy modality against cancer, but its efficacy is often limited by the amount of nanoparticles delivered to tumors. Previous studies showed a vasculature modulation treatment, which dilates or prunes tumor blood vessels, may enhance tumor uptake of nanoparticles. However, exploiting these approaches for improved PTT has seldom been studied. In this study, we investigated the impact of mild hyperthermia or anti-angiogenesis therapy on PTT. Briefly, we gave tumor-bearing balb/c mice low doses of sunitinib or submerged tumors in a 42 °C water bath. Next, we injected PEGylated reduced graphene oxide (RGO-PEG) and irradiated the tumors to induce PTT. We then followed up the treatment with multi-parameter MRI. Contrary to expectation, both vessel modulation strategies led to diminished PTT efficacy. Our results show that vessel modulation does not warrant improved PTT, and should be carefully gauged when used in combination with PTT.

This study reports three novel 18F-labeled pyridaben analogues for potential myocardial perfusion imaging (MPI). Three precursors and the corresponding nonradioactive compounds were synthesized and characterized. The radiolabeled tracers were obtained by substituting tosyl with 18F. The total radiosynthesis time of these tracers was 70–90 min. Typical decay-corrected radiochemical yields were 47–58%, with high radiochemical purities (>98%). Tracers were evaluated as MPI agents in vitro, ex vivo and in vivo. In the mouse biodistribution study, all three radiotracers showed high initial heart uptake (34–54% ID/g at 2 min after injection) and fast liver clearance. In the microPET imaging study, [18F]Fmpp2 produced heart images with good quality in both mice and rats. In the whole-body PET/CT images of mini-swine, [18F]Fmpp2 showed excellent initial heart standardized uptake value (SUV) (7.12 at 5 min p.i.) and good retention (5.75 at 120 min p.i.). The heart/liver SUV ratios were 4.12, 5.42 and 5.99 at 30, 60 and 120 min after injection, respectively. The favorable biological properties of [18F]Fmpp2 suggest that it is worth further investigation as a potential MPI agent.

Molecular imaging technique is an attractive tool to detect liver disease at early stage. This study aims to develop a simultaneous dual-isotope single photon emission computed tomography (SPECT)/CT imaging method to assist diagnosis of hepatic tumor and liver fibrosis. Animal models of liver fibrosis and orthotopic human hepatocellular carcinoma (HCC) were established. The tracers of 131I-NGA and 99mTc-3P-RGD2 were selected to target asialoglycoprotein receptor (ASGPR) on the hepatocytes and integrin αvβ3 receptor in tumor or fibrotic liver, respectively. SPECT imaging and biodistribution study were carried out to verify the feasibility and superiority. As expected, 99mTc-3P-RGD2 had the ability to evaluate liver fibrosis and detect tumor lesions. 131I-NGA showed that it was effective in assessing the anatomy and function of the liver. In synchronized dual-isotope SPECT/CT imaging, clear fusion images can be got within 30 minutes for diagnosing liver fibrosis and liver cancer. This new developed imaging approach enables the acquisition of different physiological information for diagnosing liver fibrosis, liver cancer and evaluating residual functional liver volume simultaneously. So synchronized dual-isotope SPECT/CT imaging with 99mTc-3P-RGD2 and 131I-NGA is an effective approach to detect liver disease, especially liver fibrosis and liver cancer.

The goal of this study is to develop a noninvasive method of SPECT imaging to quantify and stage liver fibrosis with an Asialoglycoprotein receptor (ASGP-R) targeting tracer—99mTc-p(VLA-co-VNI). ASGP-Rs are well known to specifically express in the mammalian liver. Here, we demonstrated ASGP-R expression decreased in carbon tetrachloride (CCl4)-induced mouse model. ASGP-R expression correlated with liver fibrosis progression. ASGP-R could be a useful marker in the stage of liver fibrosis. Liver uptake value (LUV) derived by SPECT imaging was used to assess liver fibrosis in the CCl4-induced mouse model. LUV = [radioactivity (liver uptake)/radioactivity (injected)] × 100/liver volume. The LUV decreased along with the disease progression. The relationships between LUV and liver hydroxyproline (i.e. collagen), as well as Sirius Red were established and verified. A strong negative linear correlation was found between LUV and hydroxyproline levels (r = −0.83) as well as LUV and Sirius Red quantification (r = −0.83). In conclusion, SPECT imaging with 99mTc-p(VLA-co-VNI) is useful in evaluating and staging liver fibrosis in vivo.

Selective receptor-targeting peptide based agents have attracted considerable attention in molecular imaging of tumor cells that overexpress corresponding peptide receptors due to their unique properties such as rapid clearance from circulation as well as high affinities and specificities for their targets. The rapid growth of chemistry modification techniques has enabled the design and development of various peptide-based imaging agents with enhanced metabolic stability, favorable pharmacokinetics, improved binding affinity and selectivity, better imaging ability as well as biosafety. Among them, many radiolabeled peptides have already been translated into the clinic with impressive diagnostic accuracy and sensitivity. This review summarizes the current status in the development of peptide-based imaging agents with an emphasis on the consideration of probe design including the identification of suitable peptides, the chemical modification of probes and the criteria for clinical translation. Specific examples in clinical trials have been provided as well with respect to their diagnostic capability compared with other FDA approved imaging agents.

4-[18F]flouro-3-nitro-N-2-propyn-1-yl-benzamide ([18F]FNPB) was developed as a new stable aromatic prosthetic group for more efficient click labeling of peptides. A new aromatic precursor 3,4-dinitro-N-2-propyn-1-yl-benzamide was radiofluorinated using [18F]KF/K2.2.2 followed by HPLC purification to obtain the desired product [18F]FNPB. [18F]FNPB was synthesized with a 58% radiochemical yield, a specific activity?>?350?GBq/mu mol, and radiochemical purity was exceeded 98% in 40?min. The in vitro stability studies showed no detectable radiodefluorination over 2?h in mouse plasma. The click labeling yield of three different peptides with [18F]FNPB were all above 87%. The in vitro study suggests that [18F]FNPB may be stable?in vivo and could have general application in labeling peptides with high radiochemical yield for positron emission tomography applications. Copyright (c) 2012 John Wiley & Sons, Ltd.

Angiogenesis is a key factor for post-ischemic repair of the infarcted myocardium. This study aims to monitor angiogenesis of infarcted myocardium with a positron emission tomography (PET) imaging agent, (18)F-alfatide II ((18)F-AlF-NOTA-E[PEG4-c(RGDfk)]2), targeting αvβ3 integrin after treatment with vascular endothelial growth factor (VEGF) gene and/or bone marrow mesenchymal stem cells (BMSCs). Sprague-Dawley (SD) rats underwent left coronary artery ligation and were randomly divided into four groups: normal saline control, Ad-VEGF, BMSCs, and Ad-VEGF + BMSCs (n = 4/group). The induced myocardial infarction (MI) was confirmed by electrocardiogram (ECG) with ST-segment elevation, and (99m)Tc-MIBI SPECT imaging showing defected myocardial perfusion. Alfatide II PET was performed to monitor angiogenesis at different time points after the therapy. The ratios of Alfatide II tracer uptake in the infarcted myocardium to normal myocardium in all four groups were analyzed. The PET results were validated by ex vivo tissue biodistribution, autoradiography, and immunofluorescence staining. At 1 week after therapy, elevated RGD peptide tracer uptake at the infarcted myocardium was observed in all four groups. The infarct to normal heart ratio of Alfatide II tracer for the three treatment groups was significantly higher than that of the control group (3.94 ± 0.20 for VEGF group, 3.77 ± 0.16 for BMSCs group and 4.86 ± 0.08 for the combination group vs. 3.01 ± 0.03 for the control group, P < 0.005, P < 0.005, P < 0.0001, respectively). The combination treatment group demonstrated higher contrast than the two single treatment groups. Similar results were also observed at 4 weeks after treatment. Autoradiography showed similar trend to that of PET results. Immunohistochemical staining showed expression of VEGF protein and the presence of adenovirus in the myocardium. The patterns of vascular density and integrin αvβ3 expression were measured by CD31 and CD61 immunostaining analysis, and were consistent with the PET results. (18)F-alfatide II PET could reflect angiogenesis of infarcted myocardium after VEGF gene and BMSCs therapy and further provide a non-invasive way of monitoring therapy response of myocardial infarction.

Integrins are critically involved in many tumour-promoting activities. The development of inhibitors against integrins may suppress tumour growth by inhibiting tumour angiogenic signalling. In this study, we investigated the effects of two novel peptides containing the integrin binding arginine-glycine-aspartic acid-motif on inhibiting diverse cell behaviours, including cell adhesion, motility, invasion, tube formation and cell cytoskeleton. Cell adhesion and motility assays demonstrated that cyclopeptides c-Gly and c-Lys might inhibit the adhesive and motile activity at the concentration of 25 μM. There was no significant effect on cell invasion, indicating the importance of extracellular matrix degradation in modulating the anti-invasive effect of human umbilical vein endothelial cells (HUVECs). More importantly, the tubular network formation of HUVECs was significantly inhibited by cyclopeptide c-Lys besides causing a remarkable inhibition of cytoskeletal organization, disrupting the focal adhesion and actin stress fibres formation. In conclusion, this study results indicated that the novel peptide c-Lys has the ability to inhibit diverse cell behaviours of HUVECs, and the effects may be mediated at different levels of the tumour growth. Therefore, c-Lys is perhaps proposed to be a potent anti-angiogenic drug candidate.

A simple and mild synthesis of a new family of cyclopeptide analogues cyclo[-Arg-Gly-Asp-Ψ(triazole)-Gly-Xaa-] that is obtained by cyclization with click chemistry was investigated. In addition, the method was also successfully expanded to the synthesis of their analogues of different ring sizes. The result supports the potential utility of click chemistry in the preparation of novel integrin domain-binding antagonists and other cyclopeptide analogues.

The goal of this study is to evaluate a new (18) F-labeled imaging agent for diagnosing high metastatic (aggressive) hepatocellular carcinoma using positron emission tomography (PET). The new (18) F-labeled imaging agent [(18) F]AlF-NOTA-G-TMTP1 was synthesized and radiolabeled with (18) F using NOTA-AlF chelation method. The tumor-targeting characteristics of [(18) F]AlF-NOTA-G-TMTP1 was assessed in HepG2, SMCC-7721, HCC97L and HCCLM3 xenografts. The total synthesis time was about 20 min with radiochemical yield of 25 ± 6%. The specific activity was about 11.1-14.8 GBq/µmol at the end of synthesis based on the amount of peptide used and the amount of radioactivity trapped on the C18 column. The log P value of [(18) F]AlF-NOTA-G-TMTP1 was -3.166 ± 0.022. [(18) F]AlF-NOTA-G-TMTP1 accumulated in SMCC-7721 and HCCLM3 tumors (high metastatic potential) in vivo and result in tumor/muscle (T/M) ratios of 4.5 ± 0.3 and 4.7 ± 0.2 (n = 4) as measured by PET at 40 min post-injection (p.i.). Meanwhile, the tumor/muscle (T/M) ratios of HepG2 and HCC97L tumors (low metastatic potential) were1.6 ± 0.3 and 1.8 ± 0.4. The tumor uptake of [(18) F]AlF-NOTA-G-TMTP1 could be inhibited 61.9% and 57.6% by unlabeled G-TMTP1 in SMCC-7721 and HCCLM3 xenografts at 40 min p.i., respectively. Furthermore, [(18) F]AlF-NOTA-G-TMTP1 showed pretty low activity in the liver and intestines in all tumor bearing mice, such in vivo distribution pattern would be advantageous for the detection of hepatic carcinoma. Overall, [(18) F]AlF-NOTA-G-TMTP1 may specifically target high metastatic or/and aggressive hepatocellular carcinoma with low background activity and, therefore, holds the potential to be used as an imaging agent for detecting tumor lesions within the liver area. Copyright © 2016 John WileySons, Ltd.

With the assistance of molecular docking and 3D-QSAR models established previously, structurally identical 18F- and 125I-labeled benzyloxybenzene derivatives were designed to achieve the early detection of Aβ plaques by PET/SPECT imaging. In competition binding assay, ligands 7a and 12a displayed high binding affinities to Aβ42 aggregates with Ki values of 19.5 nM and 23.9 nM, respectively. Specific plaque labeling was observed on the in vitro autoradiography of brain sections from AD patients and Tg mice. In biodistribution, [125I]7a, [18F]7a, [125I]12a and [18F]12a all exhibited high initial brain uptakes (>5% ID/g at 2 min). [125I]7a and [125I]12a cleared fast from the normal brain regions, while corresponding [18F]7a and [18F]12a showed slow washout rates. Dynamic microPET/CT and microSPECT/CT imaging data in normal ICR mice were in accordance with in vivo biodistribution results. In vivo metabolism results indicated that the different clearance profiles between the structurally identical 18F- and 125I-labeled tracers could be attributed to different biochemical characteristics of the radiometabolites. Radioiodinated benzyloxybenzene derivatives exhibited good in vivo biostability in brain. Ex vivo autoradiography further confirmed the strong in vivo Aβ labeling ability of [125I]7a. These new fluorinated and iodinated benzyloxybenzenes can develop into PET/SPECT dual imaging agents targeting Aβ plaques.