Correlating EGFR expression with receptor-binding properties and internalization of 64Cu-DOTA-cetuximab in 5 cervical cancer cell lines

First-, Second-, and Third-Generation Radiolabeled Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors in Positron Emission Tomography: State of the Art, a Systematic Review

Introduction: Lung cancer (LC) is a leading cause of death among men and women, with non-small cell LC (NSCLC) accounting for a substantial portion of the histopathological spectrum and epidermal growth factor receptor (EGFR) mutations being correlated with its manifestation and evolution. Positron emission tomography (PET)/computed tomography has been the most widely used instrument to assess and monitor LC in a noninvasive way, including EGFR-mutated NSCLC, and its course during therapy, indicating to the referring physician the response to ongoing treatment or the lack of it. This systematic review aims to evaluate the feasibility and safety of radiolabeled EGFR tyrosine kinase inhibitors (TKis) in PET in clinical practice. Materials and Methods: From 1999 to April 2022 a Medline search was conducted on four different databases such as PubMed, Cochrane Library, Scopus, and Web of Sciences. Clinical studies were assessed by Quality Assessment of Diagnostic accuracy Studies-2 (QUADAS-2) and preclinical studies were also reported in this review. Results: Nine clinical studies were QUADAS-2 assessed and risk-of-bias assessment, and it turned out acceptable as two out of eight studies had low risk of bias in all four domains for risk-of-bias assessment, and the other four studies had three low-risk domains. The overall assessment for applicability risks was low. Conclusions: Radiolabeled EGFR-TKis in PET are a valid tool in identifying patients who may benefit from TKi therapy and who may not as a means to start an effective treatment. Although the number of clinical studies conducted so far is meager, these new PET tracers are already proving to be very useful in clinical settings as patient prognosis can be better assessed.

Morphine stimulates cervical cancer cells and alleviates cytotoxicity of chemotherapeutic drugs via opioid receptor-dependent and -independent mechanisms

Morphine is frequently applied in cancer patients for pain management. However, its effects on cancer are not well understood but observed to be specific to certain cancer types. We previously revealed the stimulatory properties of morphine in esophageal carcinoma. This work addressed the effects of morphine and its underlying mechanisms in cervical cancer. Proliferation, apoptosis, and migration assays were performed to examine the effects of morphine alone and its combinatory effects with chemotherapeutic drugs. Immunoblotting and biochemical analysis were performed to determine the underlying mechanisms of morphine's action. Morphine promoted proliferation in opioid receptor-dependent manner and stimulated migration in opioid receptor-independent manner. However, morphine did not affect cervical cancer cell survival. Morphine also interfered with all tested chemotherapeutic drugs (e.g., cisplatin, 5-FU, and paclitaxel) and alleviates their efficacy. Mechanistically, morphine-stimulated growth via activating EGFR-mediated signaling pathways and is opioid-receptor-dependent; morphine-stimulated migration via activating RhoA-mediated signaling pathways and this is opioid receptor-independent. Our work suggests a strong correlation of this opioid receptor on growth factor signaling to stimulate growth and opioid receptor-independent activation of RhoA and consequent migration. Our findings have the potential to guide the clinical use of morphine for patients with cervical cancer.

Emerging roles of the copper-CTR1 axis in tumorigenesis

Physiological roles of copper in metabolic homeostasis have been well established, however, whether and how copper is dysregulated in tumors and contributes to tumorigenesis are not recapitulated. Here, we comprehensively summarize the potential origins of copper accumulation in diseases especially in cancers by dysregulating copper transporter 1 (CTR1) or ATPase copper transporting alpha/beta (ATP7A/B) and further demonstrate the underlying mechanism of copper contributing to tumorigenesis. Specifically, in addition to modulating reactive oxygen species (ROS), angiogenesis, immune response, and metabolic homeostasis, copper recently has drawn more attention by directly binding to oncoproteins such as MEK, ULK, Memo, and PDK1 to activate distinct oncogenic signals and account for tumorigenesis. In the end, we disclose the emerging applications of copper in cancer diagnosis and highlight the promising strategies to target the copper-CTR1 axis for cancer therapies.

A review on the role of epidermal growth factor signaling in the development, progression and treatment of cervical cancer

The sub-committee constituted by the Indian Council of Medical Research (ICMR) for the management of cervical cancer (CC) detailed in the consensus document (2016) reported CC as a significant cause of morbidity and mortality in women. The incidence of an increase in CC and associated mortality in women is a major cause of cancer. To date, human papilloma viral (HPV) infection accounts for more than 99% of CC. However, there are individuals infected with HPV do not develop CC. There is a greater correlation between HPV infection and upregulation of the epidermal growth factor receptor (EGFR) signaling cascade during the initiation, sustenance, and progression of CC. Therefore, EGFR is often targeted to treat CC using tyrosine kinase inhibitors (TKIs) and monoclonal antibodies (mAB). The current review analyzed the existing clinical/pre-clinical studies and the significance of EGFR abundance using the Kaplan-Meier (KM) survival plot analysis for disease-free survival (DFS) and overall survival (OS). We performed a series of bioinformatics analyses to screen the crucial role of the EGFR gene in CC. Further, different transcription factors that are dysregulated due to EGFR abundance and their relevance were determined using computational tools in this review. Endogenous microRNAs (miRNA) that undergo changes due to alterations in EGFR during CC were identified using computational database and consolidated the information obtained with the published in the area of miRNA and EGFR with special reference to the initiation, sustenance and progression of CC. The current review aims to consolidate contemporary approaches for targeting CC using EGFR and highlight the current role of miRNA and genes that are differently regulated during CC involving EGFR mutations. Potential resistance to the available EGFR therapies such as TKIs and mABs and the need for better therapies are also extensively reviewed for the development of newer therapeutic molecules with better efficacy.

Cetuximab PET delineated changes in cellular distribution of EGFR upon dasatinib treatment in triple negative breast cancer

Background

At least 50% of triple negative breast cancer (TNBC) overexpress the epidermal growth factor receptor, EGFR, which paved the way for clinical trials investigating its blockade. Outcomes remained dismal stemming from mechanisms of resistance particularly the nuclear cycling of EGFR, which is enhanced by Src activation. Attenuation of Src reversed nuclear translocation, restoring EGFR to the cell surface. Herein, we hypothesize that changes in cellular distribution of EGFR upon Src inhibition with dasatinib can be annotated through the EGFR immunopositron emission tomography (immunoPET) radiotracer, [⁸⁹Zr]Zr-cetuximab.

Methods

Nuclear and non-nuclear EGFR levels of dasatinib-treated vs. untreated MDA-MB-231 and MDA-MB-468 cells were analyzed via immunoblots. Both treated and untreated cells were exposed to [⁸⁹Zr]Zr-cetuximab to assess binding at 4 °C and 37 °C. EGFR-positive MDA-MB-231, MDA-MB-468, and a patient-derived xenograft were treated with dasatinib or vehicle followed by cetuximab PET imaging to compare EGFR levels. After imaging, the treated mice were separated into two groups: one cohort continued with dasatinib with the addition of cetuximab while the other cohort received dasatinib alone. Correlations between the radiotracer uptake vs. changes in tumor growth and EGFR expression from immunoblots were analyzed.

Results

Treated cells displayed higher binding of [⁸⁹Zr]Zr-cetuximab to the cell membrane at 4 °C and with greater internalized activity at 37 °C vs. untreated cells. In all tumor models, higher accumulation of the radiotracer in dasatinib-treated groups was observed compared to untreated tumors. Treated tumors displayed significantly decreased pSrc (Y416) with retained total Src levels compared to control. In MDA-MB-468 and PDX tumors, the analysis of cetuximab PET vs. changes in tumor volume showed an inverse relationship where high tracer uptake in the tumor demonstrated minimal tumor volume progression. Furthermore, combined cetuximab and dasatinib treatment showed better tumor regression compared to control and dasatinib-only-treated groups. No benefit was achieved in MDA-MB-231 xenografts with the addition of cetuximab, likely due to its KRAS-mutated status.

Conclusions

Cetuximab PET can monitor effects of dasatinib on EGFR cellular distribution and potentially inform treatment response in wild-type KRAS TNBC.

Targeted Delivery of 111In Into the Nuclei of EGFR Overexpressing Cells via Modular Nanotransporters With Anti-EGFR Affibody

Since cell nucleus is one of the most vulnerable compartments, the maximum therapeutic effect from a variety of locally acting agents, such as photosensitizers, alfa-emitters, Auger electron emitters, will be expected when they get there. Therefore, the targeted delivery of these agents into the nuclei of target tumor cells is necessary for their anticancer effects and minimization of side effects. Modular nanotransporters (MNT) are artificial polypeptides comprising several predefined modules that recognize target cell, launching their subsequent internalization, escape from endosomes, and transport the drug load to the nucleus. This technology significantly enhances the cytotoxicity of locally acting drugs in vitro and in vivo. Epidermal growth factor receptors (EGFR) are useful molecular targets as they are overexpressed in glioblastoma, head-and-neck cancer, bladder cancer, and other malignancies. Here, we examined the possibility of using internalizable anti-EGFR affibody as an EGFR-targeting MNT module for drug transport into the cancer cell nuclei. It binds to both murine and human EGFR facilitating preclinical studies. We showed that MNT with affibody on the N-terminus (MNT_N-affibody) effectively delivered the Auger electron emitter ¹¹¹In to target cell nuclei and had pronounced cytotoxic efficacy against EGFR-overexpressing human A431 epidermoid carcinoma cells. Using EGFR-expressing human adenocarcinoma MCF-7 cells, we demonstrated that in contrast to MNT with N-terminal epidermal growth factor (EGF), MNT_N-affibody and MNT with EGF on the C-terminus did not stimulate cancer cell proliferation.

Immuno-PET imaging for non-invasive assessment of cetuximab accumulation in non-small cell lung cancer

Backgrounds

Overexpression of epidermal growth factor receptor (EGFR) has been established as a valid therapeutic target of non-small cell lung cancer (NSCLC). However, the clinical benefit of cetuximab as an EGFR-targeting drug is still controversial, partially due to the lack of effective means to identify suitable patients. This study aimed to investigate the potential of radiolabeled cetuximab as a non-invasive tool to predict cetuximab accumulation in NSCLC tumor xenografts with varying EGFR expression levels.

Methods

The NSCLC tumors in model mice were subjected to in vivo biodistribution study and positron emission tomography (PET) imaging 48 h after injection of either ¹¹¹In- or ⁶⁴Cu-labeled cetuximab. The EGFR expression levels of NSCLC tumors were determined by ex vivo immunoblotting.

Results

We found that tumors with high EGFR expression had significantly higher [¹¹¹In]In-DOTA-cetuximab accumulation than tumors with moderate to low EGFR expression (P < 0.05). Strong correlations were found between [¹¹¹In]In-DOTA-cetuximab tumor uptake and EGFR expression level (r = 0.893), and between [⁶⁴Cu]Cu-DOTA-cetuximab tumor uptake with EGFR expression level (r = 0.915). PET imaging with [⁶⁴Cu]Cu-DOTA-cetuximab allowed clear visualization of tumors.

Conclusion

Our findings suggest that this immuno-PET imaging can be clinically translated as a tool to predict cetuximab accumulation in NSCLC cancer patients prior to cetuximab therapy.

Multifunctional graphene oxide/iron oxide nanoparticles for magnetic targeted drug delivery dual magnetic resonance/fluorescence imaging and cancer sensing

Graphene Oxide (GO) has recently attracted substantial attention in biomedical field as an effective platform for biological sensing, tissue scaffolds and in vitro fluorescence imaging. However, the targeting modality and the capability of its in vivo detection have not been explored. To enhance the functionality of GO, we combine it with superparamagnetic iron oxide nanoparticles (Fe3O4 NPs) serving as a biocompatible magnetic drug delivery addends and magnetic resonance contrast agent for MRI. Synthesized GO-Fe3O4 conjugates have an average size of 260 nm and show low cytotoxicity comparable to that of GO. Fe3O4 nanoparticles provide superparamagnetic properties for magnetic targeted drug delivery allowing simple manipulation by the magnetic field and magnetic resonance imaging with high r2/r1 relaxivity ratios of ~10.7. GO-Fe3O4 retains pH-sensing capabilities of GO used in this work to detect cancer versus healthy environments in vitro and exhibits fluorescence in the visible for bioimaging. As a drug delivery platform GO-Fe3O4 shows successful fluorescence-tracked transport of hydrophobic doxorubicin non-covalently conjugated to GO with substantial loading and 2.5-fold improved efficacy. As a result, we propose GO-Fe3O4 nanoparticles as a novel multifunctional magnetic targeted platform for high efficacy drug delivery traced in vitro by GO fluorescence and in vivo via MRI capable of optical cancer detection.

64Cu-based Radiopharmaceuticals in Molecular Imaging

Copper-64 (T_1/2 = 12.7 hours; β⁺: 19%, β^-: 38%) has a unique decay profile and can be used for positron emission tomography imaging and radionuclide therapy. The well-established coordination chemistry of copper allows for its reaction with different types of chelator systems. It can be linked to antibodies, proteins, peptides, and other biologically relevant small molecules. Two potential ways to produce copper-64 radioisotopes concern the use of the cyclotron or the reactor. This review summarized several commonly used biomarkers of copper-64 radionuclide.

PET Imaging Biomarkers of Anti-EGFR Immunotherapy in Esophageal Squamous Cell Carcinoma Models

Epidermal growth factor receptor (EGFR) is overexpressed and considered as a proper molecular target for diagnosis and targeted therapy of esophageal squamous cell carcinoma (ESCC). This study evaluated the usefulness of PET imaging biomarkers with ⁶⁴Cu-PCTA-cetuximab and ¹⁸F-FDG-PET for anti-EGFR immunotherapy in ESCC models. In vivo EGFR status and glucose metabolism by cetuximab treatment were evaluated using ⁶⁴Cu-PCTA-cetuximab and ¹⁸F-FDG-PET, respectively. Therapeutic responses with imaging biomarkers were confirmed by western blot and immunohistochemistry. TE-4 and TE-8 tumors were clearly visualized by ⁶⁴Cu-PCTA-cetuximab, and EGFR expression on TE-8 tumors showed 2.6-fold higher uptake than TE-4. Tumor volumes were markedly reduced by cetuximab in TE-8 tumor (92.5 ± 5.9%), but TE-4 tumors were refractory to cetuximab treatment. The SUVs in ⁶⁴Cu-PCTA-cetuximab and ¹⁸F-FDG-PET images were statistically significantly reduced by cetuximab treatment in TE-8 but not in TE-4. ⁶⁴Cu-PCTA-cetuximab and ¹⁸F-FDG-PET images were well correlated with EGFR and pAkt levels. ⁶⁴Cu-PCTA-cetuximab immuno-PET had a potential for determining EGFR level and monitoring therapeutic response by anti-EGFR therapy. ¹⁸F-FDG-PET was also attractive for monitoring efficacy of anti-EGFR therapy. In conclusion, PET imaging biomarkers may be useful for selecting patients that express target molecules and for monitoring therapeutic efficacy of EGFR-targeted therapy in ESCC patients.

Benzofuran-appended 4-aminoquinazoline hybrids as epidermal growth factor receptor tyrosine kinase inhibitors: synthesis, biological evaluation and molecular docking studies

A series of 2-arylbenzo[b]furan–appended 4-aminoquinazoline hybrids were prepared and evaluated for cytotoxicity in vitro against the human lung cancer (A549), colorectal adenocarcinoma (Caco-2), hepatocellular carcinoma (C3A) and cervical cancer (HeLa) cell lines. Compounds 10d and 10j exhibited significant cytotoxicity against the C3A and Caco-2 cell lines and induced apoptosis in these cell lines. Likewise, compounds 10d and 10e exhibited significant inhibitory activity towards epidermal growth factor receptor-tyrosine kinase phosphorylation (IC₅₀ values of 29.3 nM and 31.1 nM, respectively) against Gefitinib (IC₅₀ = 33.1 nM). Molecular docking of compounds 10 into EGFR-TK active site suggests that they bind to the region of EGFR like Gefitinib does.

Green synthesis of labeled CeO2 nanoparticles with 99mTc and its biodistribution evaluation in mice

AIMS

The in vivo targeted diagnostic applications of biosynthetic Cerium oxide nanoparticles (CeO₂-NPs), prepared by applying chitosan as a stabilizer, was explored by evaluating the cytotoxicity through MTT assay on WEHI 164 cell line, the Hemolytic activity of CeO₂-NPs and biodistribution in rats.

MAIN METHODS

The CeO₂-NPs were characterized through the use of TGA/DTG, PXRD, FESEM, FTIR, and UV-Vis spectroscopy. The biodistribution of CeO₂-NPs were determined by directly labeled nanoparticles with Technetium-99 m (99mTc) radioisotope (99mTc-CeO₂-NPs). The labeling efficiency and stability of 99mTc-CeO₂-NPs were also measured with Instant Thin Layer Chromatography (ITLC) method. The saturation study was investigated by 1 mCi of 99mTc-CeO₂-NPs using different concentrations of WEHI 164 cells after 4 h of incubation. In vivo biodistribution study was performed by intravenous injection of 600 μCi/200 μL 99mTc-CeO₂-NPs through rat's tail.

KEY FINDINGS

CeO₂-NPs seemed to have a low cytotoxic effect on WEHI 164 cell line and did not result in hemolysis. The biodistribution of CeO₂-NPs has shown that a huge amount of 99mTc-CeO₂-NPs was amassed in the living human organs, including liver, lung, spleen, stomach, and thyroid which shows the in vivo stability of the labeled conjugate. Herein, we have developed a facile, economical, and greener synthetic procedure applying Chitosan template. This green approach is comparable to conventional methods that utilize hazardous materials which are would be a suitable alternative to circumvent synthetic issues related to these materials.

SIGNIFICANCE

The bio-applications of nano-sized CeO₂-NPs were explored to find new horizon to use nanotechnology as the diagnostic tool.

A comprehensively revised strategy that improves the specific activity and long-term stability of clinically relevant 89Zr-immuno-PET agents

Zirconium-89 is currently being used in numerous clinical trials involving monoclonal antibodies and positron emission tomography. This report describes a revised strategy that reduces preparation time while increasing the specific activity of clinically relevant immuno-PET agents. Additionally, it demonstrates that n-acetyl-l-cysteine acts as a superior radioprotective agent that improves long-term stability without compromising antigen affinity in vivo.

Synthesis, Biological Evaluation and Molecular Docking of Novel Indole-Aminoquinazoline Hybrids for Anticancer Properties

A series of indole-aminoquinazolines was prepared via amination of the 2-aryl-4-chloroquinazolines with the 7-amino-2-aryl-5-bromoindoles. It was then evaluated for cytotoxicity in vitro against human lung cancer (A549), epithelial colorectal adenocarcinoma (Caco-2), hepatocellular carcinoma (C3A), breast adenocarcinoma (MCF-7), and cervical cancer (HeLa) cells. A combination on the quinazoline and indole moieties of a 2-phenyl and 2-(4-fluorophenyl) rings in compound 4b; 2-(4-fluorophenyl) and 3-chlorophenyl rings in compound 4f; or the two 2-(4-fluorophenyl) rings in compound 4g, resulted in significant and moderate activity against the Caco-2 and C3A cell lines. The indole-aminoquinazoline hybrids compounds 4f and 4g induced apoptosis in Caco-2 and C3A cells, and were also found to exhibit moderate (IC₅₀ = 52.5 nM) and significant (IC₅₀ = 40.7 nM) inhibitory activity towards epidermal growth factor receptor (EGFR) against gefitinib (IC₅₀ = 38.9 nM). Molecular docking suggests that 4a–h could bind to the ATP region of EGFR like erlotinib.

Integrated treatment using intraperitoneal radioimmunotherapy and positron emission tomography-guided surgery with 64Cu-labeled cetuximab to treat early- and late-phase peritoneal dissemination in human gastrointestinal cancer xenografts

Peritoneal dissemination is a common cause of death from gastrointestinal cancers and is difficult to treat using current therapeutic options, particularly late-phase disease. Here, we investigated the feasibility of integrated therapy using ⁶⁴Cu-intraperitoneal radioimmunotherapy (ipRIT), alone or in combination with positron emission tomography (PET)-guided surgery using a theranostic agent (⁶⁴Cu-labeled anti-epidermal growth factor receptor antibody cetuximab) to treat early- and late-phase peritoneal dissemination in mouse models. In this study, we utilized the OpenPET system, which has open space for conducting surgery while monitoring objects at high resolution in real time, as a novel approach to make PET-guided surgery feasible. ⁶⁴Cu-ipRIT with cetuximab inhibited tumor growth and prolonged survival with little toxicity in mice with early-phase peritoneal dissemination of small lesions. For late-phase peritoneal dissemination, a combination of ⁶⁴Cu-ipRIT for down-staging and subsequent OpenPET-guided surgery for resecting large tumor masses effectively prolonged survival. OpenPET clearly detected tumors (≥3 mm in size) behind other organs in the peritoneal cavity and was useful for confirming the presence or absence of residual tumors during an operation. These findings suggest that integrated ⁶⁴Cu therapy can serve as a novel treatment strategy for peritoneal dissemination.

Non-18F-2-Fluoro-2-Deoxy-d-Glucose PET/Computed Tomography in Gynecologic Oncology: An Overview of Current Status and Future Potential

The current status and future potential targets of non-¹⁸F-2-fluoro-2-deoxy-d-glucose (FDG) PET/computed tomography (CT) in 3 major gynecologic malignancies are discussed. Estrogen receptor-based 16alpha-¹⁸F-fluoro-17beta-estradiol (¹⁸F-FES) PET/CT has been investigated in (a) Uterine malignancies (both endometrial and myometrial pathologies) and (b) ovarian carcinoma. For uterine tumors, FDG/FES standardized uptake value and/or uptake ratio showed a positive correlation with malignant transformation (ie, endometrial carcinoma and uterine sarcoma) and higher malignant grades, whereas higher ¹⁸F-FES uptake was documented in benign pathologies (ie, endometrial hyperplasia and leiomyoma). For epithelial ovarian carcinomas, ¹⁸F-FES PET/CT can predict the response to antiestrogen therapy in platinum-resistant cases.

Novel PAMAM-PEG-Peptide Conjugates for siRNA Delivery Targeted to the Transferrin and Epidermal Growth Factor Receptors

The transferrin (TfR) and epidermal growth factor receptors (EGFR) are known to be overexpressed on the surface of a wide variety of tumor cells. Therefore, the peptides B6 (TfR specific) and GE11 (targeted to the EGFR) were linked to the PAMAM (polyamidoamine) structure via a polyethylenglycol (PEG) 2 kDa chain with the aim of improving the silencing capacity of the PAMAM-based dendriplexes. The complexes showed an excellent binding capacity to the siRNA with a maximal condensation at nitrogen/phosphate (N/P) 2. The nanoparticles formed exhibited hydrodynamic diameters below 200 nm. The zeta potential was always positive, despite the complexes containing the PEG chain in the structure showing a drop of the values due to the shielding effect. The gene silencing capacity was assayed in HeLa and LS174T cells stably transfected with the eGFPLuc cassette. The dendriplexes containing a specific anti luciferase siRNA, assayed at different N/P ratios, were able to mediate a mean decrease of the luciferase expression values of 14% for HeLa and 20% in LS174T cells, compared to an unspecific siRNA-control. (p < 0.05). In all the conditions assayed, dendriplexes resulted to be non-toxic and viability was always above 75%.

Preclinical evaluation of the anti-tumor effects of the natural isoflavone genistein in two xenograft mouse models monitored by [18F]FDG, [18F]FLT, and [64Cu]NODAGA-cetuximab small animal PET

The natural phytoestrogen genistein is known as protein kinase inhibitor and tumor suppressor in various types of cancers. We studied its antitumor effect in two different xenograft models using positron emission tomography (PET) in vivo combined with ex vivo histology and nuclear magnetic resonance (NMR) metabolic fingerprinting.

Novel Tumor Pretargeting System Based on Complementary l-Configured Oligonucleotides

Unnatural mirror image l-configured oligonucleotides (L-ONs) are a convenient substance class for the application as complementary in vivo recognition system between a tumor specific antibody and a smaller radiolabeled effector molecule in pretargeting approaches. The high hybridization velocity and defined melting conditions are excellent preconditions of the L-ON based methodology. Their high metabolic stability and negligible unspecific binding to endogenous targets are superior characteristics in comparison to their d-configured analogs. In this study, a radiopharmacological evaluation of a new l-ONs based pretargeting system using the epidermal growth factor receptor (EGFR) specific antibody cetuximab (C225) as target-seeking component is presented. An optimized PEGylated 17mer-L-DNA was conjugated with p-SCN-Bn-NOTA (NOTA') to permit radiolabeling with the radionuclide ⁶⁴Cu. C225 was modified with the complementary 17mer-L-DNA (c-L-DNA) strand as well as with NOTA' for radiolabeling and use for positron emission tomography (PET). Two C225 conjugates were coupled with 1.5 and 5.0 c-L-DNA molecules, respectively. In vitro characterization was done with respect to hybridization studies, competition and saturation binding assays in EGFR expressing squamous cell carcinoma cell lines A431 and FaDu. The modified C225 derivatives exhibited high binding affinities in the low nanomolar range to the EGFR. PET and biodistribution experiments on FaDu tumor bearing mice with directly ⁶⁴Cu-labeled NOTA'₃-C225-(c-L-DNA)_1.5 conjugate revealed that a pretargeting interval of 24 h might be a good compromise between tumor accumulation, internalization, blood background, and liver uptake of the antibody. Despite internalization of the antibody in vivo pretargeting experiments showed an adequate hybridization of ⁶⁴Cu-radiolabeled NOTA'-L-DNA to the tumor located antibody and a good tumor-to-muscle ratio of about 11 resulting in a clearly visible image of the tumor after 24 h up to 72 h. Furthermore, low accumulation of radioactivity in organs responsible for metabolism and excretion was determined. The presented results indicate a high potential of complementary L-ONs for the pretargeting approach which can also be applied to therapeutic radionuclides such as ¹⁷⁷Lu, ⁹⁰Y, ¹⁸⁶Re, or ¹⁸⁸Re.

EGFR-targeted Chimeras of Pseudomonas ToxA released into the extracellular milieu by attenuated Salmonella selectively kill tumor cells

Tumor-targeted Salmonella VNP20009 preferentially replicate within tumor tissue and partially suppress tumor growth in murine tumor models. These Salmonella have the ability to locally induce apoptosis when they are in direct contact with cancer cells but they lack significant bystander killing, which may correlate with their overall lack of antitumor activity in human clinical studies. In order to compensate for this deficiency without enhancing overall toxicity, we engineered the bacteria to express epidermal growth factor receptor (EGFR)-targeted cytotoxic proteins that are released into the extracellular milieu. In this study, we demonstrate the ability of the Salmonella strain VNP20009 to produce three different forms of the Pseudomonas exotoxin A (ToxA) chimeric with a tumor growth factor alpha (TGFα) which results in its producing culture supernatants that are cytotoxic and induce apoptosis in EGFR positive cancer cells as measured by the tetrazolium dye reduction, and Rhodamine 123 and JC-10 mitochondrial depolarization assays. In addition, exchange of the ToxA REDLK endoplasmic reticulum retention signal for KDEL and co-expression of the ColE3 lysis protein resulted in an overall increased cytotoxicity compared to the wild type toxin. This approach has the potential to significantly enhance the antitumor activity of VNP20009 while maintaining its previously established safety profile. Biotechnol. Bioeng. 2016;113: 2698-2711. © 2016 The Authors. Biotechnology and Bioengineering published by Wiley Periodicals, Inc.

99m Tc-anti-epidermal growth factor receptor nanobody for tumor imaging

Nanobodies are important biomolecules for tumor targeting. In this study, we synthesized and labeled anti-epidermal growth factor receptor (EGFR) nanobody OA-cb6 with ^99m Tc(CO)₃⁺ and evaluated its characteristics for targeting the EGFR in the A431 human epidermal carcinoma cell line. Nanobody radiolabeling was achieved with high yield and radiochemical purity, and the radioconjugate was stable. Biodistribution results in nude mice exhibited a favorable tumor-to-muscle ratio at 4-hr postinjection, and tumor location was visualized at 4 hr after injection of radiolabeled nanobody. Our result showed that the OA-cb6-^99m Tc-tricarbonyl radiolabeled nanobody is a promising radiolabeled biomolecule for tumor imaging in cancers with high EGFR overexpression.

Personalizing NSCLC therapy by characterizing tumors using TKI-PET and immuno-PET

Non-small cell lung cancer (NSCLC) therapy has entered a rapidly advancing era of precision medicine with an ever increasing number of drugs directed against a variety of specific tumor targets. Amongst these new agents, tyrosine kinase inhibitors (TKIs) and monoclonal antibodies (mAbs) are most frequently used. However, as only a sensitive subgroup of patients benefits from targeting drugs, predictive biomarkers are needed. Positron emission tomography (PET) may offer such a biomarker for predicting therapy efficacy. Some of the TKIs and mAbs that are in clinical use can be radioactively labeled and used as tracers. PET can visualize and quantify tumor specific uptake of radiolabeled targeting drugs, allowing for characterization of their pharmacokinetic behavior. In this review, the clinical potential of PET using radiolabeled TKIs (TKI-PET) and mAbs (immuno-PET) in NSCLC is discussed, and an overview is provided of the most relevant preclinical and clinical studies.

Copper-64 Radiopharmaceuticals for Oncologic Imaging

The positron emitting radionuclide (64)Cu has a radioactive half-life of 12.7 hours. The decay characteristics of (64)Cu allow for PET images that are comparable in quality to those obtained using (18)F. Given the longer radioactive half-life of (64)Cu compared with (18)F and the versatility of copper chemistry, copper is an attractive alternative to the shorter-lived nuclides for PET imaging of peptides, antibodies, and small molecules that may require longer circulation times. This article discusses a number of copper radiopharmaceuticals, such as Cu-ATSM, that have been translated to the clinic and new developments in copper-based radiopharmaceuticals.

Molecular Fluorescence Endoscopy Targeting Vascular Endothelial Growth Factor A for Improved Colorectal Polyp Detection

Small and flat adenomas are known to carry a high miss-rate during standard white-light endoscopy. Increased detection rate may be achieved by molecular fluorescence endoscopy with targeted near-infrared (NIR) fluorescent tracers. The aim of this study was to validate vascular endothelial growth factor A (VEGF-A) and epidermal growth factor receptor (EGFR)-targeted fluorescent tracers during ex vivo colonoscopy with an NIR endoscopy platform.

METHODS

VEGF-A and EGFR expression was determined by immunohistochemistry on a large subset of human colorectal tissue samples--48 sessile serrated adenomas/polyps, 70 sporadic high-grade dysplastic adenomas, and 19 hyperplastic polyps--and tissue derived from patients with Lynch syndrome--78 low-grade dysplastic adenomas, 57 high-grade dysplastic adenomas, and 31 colon cancer samples. To perform an ex vivo colonoscopy procedure, 14 mice with small intraperitoneal EGFR-positive HCT116(luc) tumors received intravenous bevacizumab-800CW (anti-VEGF-A), cetuximab-800CW (anti-EGFR), control tracer IgG-800CW, or sodium chloride. Three days later, 8 resected HCT116(luc) tumors (2-5 mm) were stitched into 1 freshly resected human colon specimen and followed by an ex vivo molecular fluorescence colonoscopy procedure.

RESULTS

Immunohistochemistry showed high VEGF-A expression in 79%-96% and high EGFR expression in 51%-69% of the colorectal lesions. Both targets were significantly overexpressed in the colorectal lesions, compared with the adjacent normal colon crypts. During ex vivo molecular fluorescence endoscopy, all tumors could clearly be delineated for both bevacizumab-800CW and cetuximab-800CW tracers. Specific tumor uptake was confirmed with fluorescent microscopy showing, respectively, stromal and cell membrane fluorescence.

CONCLUSION

VEGF-A is a promising target for molecular fluorescence endoscopy because it showed a high protein expression, especially in sessile serrated adenomas/polyps and Lynch syndrome. We demonstrated the feasibility to visualize small tumors in real time during colonoscopy using a NIR fluorescence endoscopy platform, providing the endoscopist a wide-field red-flag technique for adenoma detection. Clinical studies are currently being performed in order to provide in-human evaluation of our approach.

In vitro baselining of new pyrrolopyrimidine EGFR-TK inhibitors with Erlotinib

Epidermal growth factor receptor tyrosine kinase inhibitors are useful in treatment of non-small cell lung cancer, and show promise in combination therapy settings. Two novel chiral pyrrolopyrimidines have been baselined towards Erlotinib, Lapatinib and Dasatinib using in vitro cellular studies and ADME profiling. One of these, (S)-2-((6-(4-(hydroxymethyl)-2-methoxyphenyl)-7H-pyrrolo[2,3-d]pyrimidin-4-yl)amino)-2-phenylethan-1-ol, was more active than Erlotinib in lung and breast cancer cell models. The compound also had promising activity towards ovarian cancer cell lines, while low activity was seen towards cells of haematological origin. ADME profiling revealed good solubility, higher metabolic stability than Erlotinib and no inhibitory effect towards the hERG voltage-gated ion channel. Investigation of inhibitory potency towards 6 CYP isoforms generally revealed low inhibitory potency, but in the case of CYP3A4, a substrate dependent inhibition was noted using testosterone as substrate (IC50: 12.5μM). No cellular or gene toxicity was noted for the compounds or products of phase I metabolism. However, permeability studies using Caco-2 cells revealed a high efflux ratio. Further experiments using ABC transporter inhibitors revealed that the pyrrolopyrimidines are actively transported by the breast cancer resistant protein and P-glycoprotein transporters, which might prevent their further development into drugs.

PET of EGFR with (64) Cu-cetuximab-F(ab')2 in mice with head and neck squamous cell carcinoma xenografts

Overexpression of the epidermal growth factor receptor (EGFR) is linked to an adverse outcome in various solid tumors. Cetuximab is an EGFR inhibitor, which in combination with radiotherapy improves locoregional control and survival in a subgroup of patients with head and neck squamous cell carcinomas (HNSCCs). The aim of this study was to develop and characterize an EGFR-directed PET tracer, (64) Cu-cetuximab-F(ab')2, to determine the systemic accessibility of EGFR. Mice with HNSCC xenografts, UT-SCC-8 (n = 6) or UT-SCC-45 (n = 6), were imaged 24 h post injection with (64) Cu-NODAGA-cetuximab-F(ab')2 using PET/CT. One mouse for each tumor model was co-injected with excess unlabeled cetuximab 3 days before radiotracer injection to determine non-EGFR-mediated uptake. Ex vivo biodistribution of the tracer was determined and tumors were analyzed by autoradiography and immunohistochemistry. The SUVmax of UT-SCC-8 tumors was higher than that of UT-SCC-45: 1.5 ± 1.0 and 0.8 ± 0.2 (p < 0.05), respectively. SUVmax after in vivo blocking of EGFR with cetuximab was 0.4. Immunohistochemistry showed that UT-SCC-8 had a significantly higher EGFR expression than UT-SCC-45: 0.50 ± 0.19 versus 0.12 ± 0.08 (p < 0.005), respectively. Autoradiography indicated that (64) Cu-cetuximab-F(ab')2 uptake correlated with EGFR expression in both tumors: r = 0.86 ± 0.06 (UT-SCC-8) and 0.90 ± 0.06 (UT-SCC-45). (64) Cu-cetuximab-F(ab')2 is a promising PET tracer to determine expression of EGFR in vivo. Clinically, this tracer has the potential to be used to determine cetuximab targeting of tumors and possibly to non-invasively monitor the response to EGFR-inhibitor treatment.

A novel PET imaging using ⁶⁴Cu-labeled monoclonal antibody against mesothelin commonly expressed on cancer cells

Mesothelin (MSLN) is a 40-kDa cell differentiation-associated glycoprotein appearing with carcinogenesis and is highly expressed in many human cancers, including the majority of pancreatic adenocarcinomas, ovarian cancers, and mesotheliomas, while its expression in normal tissue is limited to mesothelial cells lining the pleura, pericardium, and peritoneum. Clone 11-25 is a murine hybridoma secreting monoclonal antibody (mAb) against human MSLN. In this study, we applied the 11-25 mAb to in vivo imaging to detect MSLN-expressing tumors. In in vitro and ex vivo immunochemical studies, we demonstrated specificity of 11-25 mAb to membranous MSLN expressed on several pancreatic cancer cells. We showed the accumulation of Alexa Fluor 750-labeled 11-25 mAb in MSLN-expressing tumor xenografts in athymic nude mice. Then, 11-25 mAb was labeled with ⁶⁴Cu via a chelating agent DOTA and was used in both in vitro cell binding assay and in vivo positron emission tomography (PET) imaging in the tumor-bearing mice. We confirmed that ⁶⁴Cu-labeled 11-25 mAb highly accumulated in MSLN-expressing tumors as compared to MSLN-negative ones. The ⁶⁴Cu-labeled 11-25 mAb is potentially useful as a PET probe capable of being used for wide range of tumors, rather than ¹⁸F-FDG that occasionally provides nonspecific accumulation into the inflammatory lesions.

Molecular imaging of targeted therapies with positron emission tomography: the visualization of personalized cancer care

INTRODUCTION

Molecular imaging has been defined as the visualization, characterization and measurement of biological processes at the molecular and cellular level in humans and other living systems. In oncology it enables to visualize (part of) the functional behaviour of tumour cells, in contrast to anatomical imaging that focuses on the size and location of malignant lesions. Available molecular imaging techniques include single photon emission computed tomography (SPECT), positron emission tomography (PET) and optical imaging. In PET, a radiotracer consisting of a positron emitting radionuclide attached to the biologically active molecule of interest is administrated to the patient. Several approaches have been undertaken to use PET for the improvement of personalized cancer care. For example, a variety of radiolabelled ligands have been investigated for intratumoural target identification and radiolabelled drugs have been developed for direct visualization of the biodistibution in vivo, including intratumoural therapy uptake. First indications of the clinical value of PET for target identification and response prediction in oncology have been reported. This new imaging approach is rapidly developing, but uniformity of scanning processes, standardized methods for outcome evaluation and implementation in daily clinical practice are still in progress. In this review we discuss the available literature on molecular imaging with PET for personalized targeted treatment strategies.

CONCLUSION

Molecular imaging with radiolabelled targeted anticancer drugs has great potential for the improvement of personalized cancer care. The non-invasive quantification of drug accumulation in tumours and normal tissues provides understanding of the biodistribution in relation to therapeutic and toxic effects.

Comparison of conjugation strategies of cross-bridged macrocyclic chelators with cetuximab for copper-64 radiolabeling and PET imaging of EGFR in colorectal tumor-bearing mice

Epidermal growth-factor receptor (EGFR) is overexpressed in a wide variety of solid tumors and has served as a well-characterized target for cancer imaging and therapy. Cetuximab was the first mAb targeting EGFR approved by the FDA for the treatment of metastatic colorectal and head and neck cancers. Previous studies showed that (64)Cu (T1/2 = 12.7 h; β(+) (17.4%)) labeled DOTA-cetuximab showed promise for PET imaging of EGFR-positive tumors; however the in vivo stability of this compound has been questioned. In this study, two recently developed cross-bridged macrocyclic chelators (CB-TE1A1P and CB-TE1K1P) were conjugated to cetuximab using standard NHS coupling procedures and/or strain-promoted azide-alkyne cycloaddition (SPAAC) methodologies. The radiolabeling and in vitro/vivo evaluation of the resulting cetuximab conjugates were compared. Improved Cu-64 labeling efficiency and high specific activity (684 kBq/μg, decay corrected to the end of bombardment) were obtained with the CB-TE1K1P-PEG4-click-cetuximab conjugate. Saturation binding assays indicated that the prepared cetuximab conjugates had comparable affinity (1.32-2.00 nM) in the HCT116 human colorectal tumor cell membranes. In the subsequent in vivo evaluation, (64)Cu-CB-TE1K1P-PEG4-click-cetuximab demonstrated more rapid renal clearance with a higher tumor/nontumor ratio than other (64)Cu-labeled cetuximab conjugates, and it shows the greatest promise for imaging and therapy of EGFR-positive tumors.

Radiolabeled Cetuximab Conjugates for EGFR Targeted Cancer Diagnostics and Therapy

The epidermal growth factor receptor (EGFR) has evolved over years into a main molecular target for the treatment of different cancer entities. In this regard, the anti-EGFR antibody cetuximab has been approved alone or in combination with: (a) chemotherapy for treatment of colorectal and head and neck squamous cell carcinoma and (b) with external radiotherapy for treatment of head and neck squamous cell carcinoma. The conjugation of radionuclides to cetuximab in combination with the specific targeting properties of this antibody might increase its therapeutic efficiency. This review article gives an overview of the preclinical studies that have been performed with radiolabeled cetuximab for imaging and/or treatment of different tumor models. A particularly promising approach seems to be the treatment with therapeutic radionuclide-labeled cetuximab in combination with external radiotherapy. Present data support an important impact of the tumor micromilieu on treatment response that needs to be further validated in patients. Another important challenge is the reduction of nonspecific uptake of the radioactive substance in metabolic organs like liver and radiosensitive organs like bone marrow and kidneys. Overall, the integration of diagnosis, treatment and monitoring as a theranostic approach appears to be a promising strategy for improvement of individualized cancer treatment.

The combination of the antiviral agent cidofovir and anti-EGFR antibody cetuximab exerts an antiproliferative effect on HPV-positive cervical cancer cell lines' in-vitro and in-vivo xenografts

Cervical carcinoma remains a leading cause of female mortality worldwide and over 90% of these tumors contain the human papillomavirus (HPV) genome. Cross-talk between the epidermal growth factor receptor and HPV has been reported and is implicated in tumor progression. The combination of the antiviral compound cidofovir (Cd) with the monoclonal antibody antiepidermal growth factor receptor cetuximab (Cx) was evaluated. HPV-positive (HeLa and Me180) and HPV-negative (C33A, H460 and A549) human cancer cell lines were incubated with Cd (1-10 μg/ml) and/or Cx (10 or 50 μg/ml). The antitumor effect of the combination was assessed in vitro using a clonogenic survival assay, cell cycle analysis, and phospho-H2AX level. Tumor growth delay was assayed in vivo using xenograft models. A pan-genomic analysis was carried out to identify the genes expressed differentially in untreated HeLa HPV-positive cells versus cells treated by the Cd-Cx combination. The Cd-Cx combination inhibited proliferation in all the cell lines tested. The association of Cd and Cx exerted a synergistic activity on HPV-positive but not on HPV-negative cell lines. The combination delayed tumor growth of HPV-positive tumors in vivo; however, no efficacy was reported on HPV-negative C33A xenografts nor on cell lines treated by single-drug therapy. The combination induced an S-phase arrest associated with an enhanced level of the double-strand break in Me180 and HeLa cell lines. Gene profiling assays showed a significant differential modulation of genes in HeLa cell lines treated with the combination involving the EGR-1 transcription factor. The current data support a synergistic antiproliferative action of the Cd-Cx combination on HPV-related cervical tumors.

Interrogating tumor metabolism and tumor microenvironments using molecular positron emission tomography imaging. Theranostic approaches to improve therapeutics

Positron emission tomography (PET) is a noninvasive molecular imaging technology that is becoming increasingly important for the measurement of physiologic, biochemical, and pharmacological functions at cellular and molecular levels in patients with cancer. Formation, development, and aggressiveness of tumor involve a number of molecular pathways, including intrinsic tumor cell mutations and extrinsic interaction between tumor cells and the microenvironment. Currently, evaluation of these processes is mainly through biopsy, which is invasive and limited to the site of biopsy. Ongoing research on specific target molecules of the tumor and its microenvironment for PET imaging is showing great potential. To date, the use of PET for diagnosing local recurrence and metastatic sites of various cancers and evaluation of treatment response is mainly based on [(18)F]fluorodeoxyglucose ([(18)F]FDG), which measures glucose metabolism. However, [(18)F]FDG is not a target-specific PET tracer and does not give enough insight into tumor biology and/or its vulnerability to potential treatments. Hence, there is an increasing need for the development of selective biologic radiotracers that will yield specific biochemical information and allow for noninvasive molecular imaging. The possibility of cancer-associated targets for imaging will provide the opportunity to use PET for diagnosis and therapy response monitoring (theranostics) and thus personalized medicine. This article will focus on the review of non-[(18)F]FDG PET tracers for specific tumor biology processes and their preclinical and clinical applications.

Imaging EGFR and HER2 by PET and SPECT: a review

In an effort to discover a noninvasive method for predicting which cancer patients will benefit from therapy targeting the EGFR and HER2 proteins, a large body of the research has been conducted toward the development of PET and SPECT imaging agents, which selectively target these receptors. We provide a general overview of the advances made toward imaging EGFR and HER2, detailing the investigation of PET and SPECT imaging agents ranging in size from small molecules to monoclonal antibodies.

Asymmetric liposome particles with highly efficient encapsulation of siRNA and without nonspecific cell penetration suitable for target-specific delivery

The discovery of siRNA has been an important step in gene therapy, but the problem of delivering siRNA to a target organ limits its use as a therapeutic drug. Liposomes can be used as a nonviral vector to deliver siRNA to target cells. In this study we developed a novel method of producing asymmetric liposome particles (ALPs) with highly efficient siRNA encapsulation. Two kinds of lipid inverted micelles were prepared for the purpose of obtaining ALPs. The inner one is composed of ionizable cationic 1,2-dioleoyl-3-dimethylammonium-propane (DODAP) and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), which entrap siRNA, and the outer one is composed of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), DOPE, polyethylene glycol-1,2-distearoyl-sn-glycero-3-phosphatidylethanolamine (PEG-PE), and cholesterol. After mixing the inverted micelles, ALPs encapsulating siRNA were obtained by solvent evaporation and dialysis. This process allowed more than 90% siRNA encapsulation as well as the negatively charged surface. The ALPs protected siRNA from ribonuclease A degradation. ALPs without any surface modification elicited almost no uptake into cells, while the surface-modified ALPs with a polyarginine peptide (R12) induced nonspecific cell penetration. The conjugation of the anti-human epidermal growth factor receptor antibody (anti-EGFR) to ALPs induces an EGFR-mediated uptake into the non-small cell lung cancer cell lines but not into NIH-3T3 cells without the receptor. The siRNA encapsulated in ALPs showed the R12- or anti-EGFR-dependent target gene silencing in NCI-H322 cells. These properties of ALPs are useful for target-specific delivery of siRNA after modification of ALPs with a target-specific ligand.

The role of p53 in combination radioimmunotherapy with 64Cu-DOTA-cetuximab and cisplatin in a mouse model of colorectal cancer

Radioimmunotherapy has been successfully used in the treatment of lymphoma but thus far has not demonstrated significant efficacy in humans beyond disease stabilization in solid tumors. Radioimmunotherapy with (64)Cu was highly effective in a hamster model of colorectal cancer, but targeted radiotherapies with this radionuclide have since not shown as much success. It is widely known that mutations in key proteins play a role in the success or failure of cancer therapies. For example, the KRAS mutation is predictive of poor response to anti-epidermal growth factor receptor therapies in colorectal cancer, whereas p53 is frequently mutated in tumors, causing resistance to multiple therapeutic regimens.

METHODS

We previously showed that nuclear localization of (64)Cu-labeled DOTA-cetuximab was enhanced in p53 wild-type tumor cells. Here, we examine the role of p53 in the response to radioimmunotherapy with (64)Cu-DOTA-cetuximab in KRAS-mutated HCT116 tumor-bearing mice, with and without cisplatin, which upregulates wild-type p53.

RESULTS

Experiments with HCT116 cells that are p53 +/+ (p53 wild-type) and -/- (p53 null) grown in cell culture demonstrated that preincubation with cisplatin increased expression of p53 and subsequently enhanced localization of (64)Cu from (64)Cu-acetate and (64)Cu-DOTA-cetuximab to the tumor cell nuclei. Radioimmunotherapy studies in p53-positive HCT116 tumor-bearing mice, receiving either radioimmunotherapy alone or in combination with cisplatin, showed significantly longer survival in mice receiving unlabeled cetuximab or cisplatin alone or in combination (all, P < 0.01). In contrast, the p53-negative tumor-bearing mice treated with radioimmunotherapy alone or combined with cisplatin showed no survival advantage, compared with control groups (all, P > 0.05).

CONCLUSION

Together, these data suggest that (64)Cu specifically delivered to epidermal growth factor receptor-positive tumors by cetuximab can suppress tumor growth despite the KRAS status and present opportunities for personalized clinical treatment strategies in colorectal cancer.

Micelle-based activatable probe for in vivo near-infrared optical imaging of cancer biomolecules

Near-infrared (NIR: 800-1000 nm) fluorescent probes, which activate their fluorescence following interaction with functional biomolecules, are desirable for noninvasive and sensitive tumor diagnosis due to minimal tissue interference. Focusing on bioavailability and applicability, we developed a probe with a self-assembling polymer micelle, a lactosome, encapsulating various quantities of NIR dye (IC7-1). We also conjugated anti-HER2 single chain antibodies to the lactosome surface and examined the probe's capacity to detect HER2 in cells and in vivo. Micelles encapsulating 20mol% IC7-1 (hIC7L) showed 30-fold higher fluorescence (λem: 858 nm) after micelle denaturation compared to aqueous buffer. Furthermore, antibody modification allowed specific activation of the probe (HER2-hIC7L) following internalization by HER2-positive cells, with the probe concentrating in lysosomes. HER2-hIC7L intravenously administered to mice clearly and specifically visualized HER2-positive tumors by in vivo optical imaging. These results indicate that HER2-hIC7L is a potential activatable NIR probe for sensitive tumor diagnosis.

FROM THE CLINICAL EDITOR

Near-infrared probes that activate their fluorescence following interaction with specific biomolecules are desirable for noninvasive and sensitive tumor detection due to minimal tissue interference. This team of authors developed a probe termed hIC7L and demonstrate its potential in HER2 tumor diagnosis.

Evaluation and comparison of human absorbed dose of (90)Y-DOTA-Cetuximab in various age groups based on distribution data in rats

The organ radiation-absorbed doses have been evaluated for humans in six age groups and both genders based on animal data. After intravenous administration of ⁹⁰Y-DOTA-Cetuximab to five groups of rats, they were sacrificed at exact time intervals (2, 24, 48, 72, and 96 h) and the percentage of injected dose per gram of each organ was calculated by direct counting from rat data. By using the formulation that Medical Internal Radiation Dose suggests, radiation-absorbed doses for all organs were calculated and extrapolated from rat to human. The total body absorbed dose for all groups was >22 mGy due to pure β-emission of the applied radiopharmaceutical. The effective dose resulting from an intravenously injected activity of 100 MBq is 56.7 mSv for a 60-kg female adult and 60.3 mSv for a 73-kg male adult. The results demonstrated the usefulness of this method for estimation of β-absorbed dose in humans.

Alternative PET tracers in head and neck cancer. A review

Positron emission tomography (PET) has become a standard in staging Head and Neck cancer. While (18)F-fluoro-2-deoxy-D-glucose (FDG) is the most frequently used radiopharmaceutical, glycolysis is not the only metabolic process that can be visualized. Different PET tracers can also be used to visualize other metabolic processes and in this manner, the disadvantages of FDG PET can be avoided. In this review, we describe a comprehensive overview of alternatives to FDG that can be used in identifying head and neck cancer. The potential advantages and disadvantages of these radiopharmaceuticals are discussed.

Tissue biomarkers as prognostic variables of cervical cancer

The most important prognostic variables of cervical carcinoma are FIGO stage, lymph node status and clinical-pathological features of primary tumor. Recently, there has been increasing interest in the identification of biomarkers able to predict both response to treatment and survival. The aim of this review is to critically evaluate current published evidence on the ability of various tissue biomarkers to predict the clinical outcome of patients with cervical carcinoma. In particular, the paper takes into account DNA content, cell-cycle and apoptosis-regulatory proteins, epidermal growth factor receptor [EGFR], vascular endothelial growth factor [VEGF], cyclooxygenase [COX]-2, signal transducer and activator of transcription [Stat]3, human papilloma virus [HPV] status, tumor hypoxia, tumor infiltrating lymphocytes [TIL], microarray technology and microRNA (miRNA). The presence of HPV-18 genotype and an elevated VEGF expression appear to be poor prognostic factors in women with early disease treated with primary surgery, whereas the expression of EGFR, VEGF, COX-2 and tumor hypoxia may have a major impact on the survival of patients treated with definitive radiotherapy or chemoradiation. The data supporting the reliability of ΔNp73 and TAp73α as novel biomarkers of response to radiotherapy are interesting but still limited. DNA microarray technology could offer new laboratory tools for a rationale planning of treatment strategy, and miRNAs might represent new candidate targets to be investigated for both prognostic and therapeutic purposes. Moreover, the assessment of different types of TIL and their ligands in tumor biopsies could enable the identification of a subset of high-risk patients, paving the way to novel immune therapies aimed at blocking T-reg cell activity.

Rift Valley fever virus strain MP-12 enters mammalian host cells via caveola-mediated endocytosis

Rift Valley fever virus (RVFV) is a zoonotic pathogen capable of causing serious morbidity and mortality in both humans and livestock. The lack of efficient countermeasure strategies, the potential for dispersion into new regions, and the pathogenesis in humans and livestock make RVFV a serious public health concern. The receptors, cellular factors, and entry pathways used by RVFV and other members of the family Bunyaviridae remain largely uncharacterized. Here we provide evidence that RVFV strain MP-12 uses dynamin-dependent caveola-mediated endocytosis for cell entry. Caveolae are lipid raft domains composed of caveolin (the main structural component), cholesterol, and sphingolipids. Caveola-mediated endocytosis is responsible for the uptake of a wide variety of host ligands, as well as bacteria, bacterial toxins, and a number of viruses. To determine the cellular entry mechanism of RVFV, we used small-molecule inhibitors, RNA interference (RNAi), and dominant negative (DN) protein expression to inhibit the major mammalian cell endocytic pathways. Inhibitors and RNAi specific for macropinocytosis and clathrin-mediated endocytosis had no effect on RVFV infection. In contrast, inhibitors of caveola-mediated endocytosis, and RNAi targeted to caveolin-1 and dynamin, drastically reduced RVFV infection in multiple cell lines. Expression of DN caveolin-1 also reduced RVFV infection significantly, while expression of DN EPS15, a protein required for the assembly of clathrin-coated pits, and DN PAK-1, an obligate mediator of macropinocytosis, had no significant impact on RVFV infection. These results together suggest that the primary mechanism of RVFV MP-12 uptake is dynamin-dependent, caveolin-1-mediated endocytosis.