Specific Tumor Localization Research Articles

A High-Throughput Screening Strategy for Synthesizing Molecularly Imprinted Polymer Nanoparticles Selectively Targeting Tumors.

Molecularly imprinted polymers (MIPs) show significant promise as effective alternatives to antibodies in disease diagnosis and therapy. However, the challenging process of screening extensive libraries of monomer combinations and synthesis conditions to identify formulations with enhanced selectivity and affinity presents a notable time constraint. The need for expedient methods becomes clear in accelerating the strategic development of MIPs tailored for precise molecular recognition purposes. In this study, an innovative high-throughput screening methodology designed to identify the optimal MIP formulation for targeting tumors is presented. Employing a microtiter plate format, over 100 polymer syntheses are conducted, incorporating diverse combinations of functional monomers. Evaluation of binding performance utilizes fluorescence-based assays, focusing on an epitope of the epidermal growth factor receptor (EGFR). Through this meticulously structured screening process, synthesis conditions that produced MIP nanoparticles exhibiting substantial specificity for EGFR targeting (KD = 10-12m) are identified. These "bionic antibodies" demonstrate selective recognition of cancer cells in whole blood samples, even at concentrations as low as 5cellsmL-1. Further validation through fluorescent imaging confirms the tumor-specific localization of the MIPs in vivo. This highly efficient screening approach facilitates the strategic synthesis of imprinted polymers functioning as precision bioprobes.

PITX2 as a Sensitive and Specific Marker of Midgut Neuroendocrine Tumors: Results from a Cohort of 1157 Primary Neuroendocrine Neoplasms

As neuroendocrine tumors (NETs) often present as metastatic lesions, immunohistochemical assignment to a site of origin is one of the most important tasks in their pathologic assessment. Because a fraction of NETs eludes the typical expression profiles of their primary localization, additional sensitive and specific markers are required to improve diagnostic certainty.We investigated the expression of the transcription factor Pituitary Homeobox 2 (PITX2) in a large-scale cohort of 909 NET and 248 neuroendocrine carcinomas (NEC) according to the immunoreactive score (IRS) and correlated PITX2 expression groups with general tumor groups and primary localization.PITX2 expression (all expression groups) was highly sensitive (98.1%) for midgut-derived NET, but not perfectly specific, as non–midgut NET (especially pulmonary/duodenal) were quite frequently weak or moderately positive. The specificity rose to 99.5% for a midgut origin of NET if only a strong PITX2 expression was considered, which was found in only 0.5% (one pancreatic/one pulmonary) of non–midgut NET. In metastases of midgut-derived NET, PITX2 was expressed in all cases (87.5% strong, 12.5% moderate), whereas CDX2 was negative or only weakly expressed in 31.3% of the metastases. In NEC, a fraction of cases (14%) showed a weak or moderate PITX2 expression, which was not associated with a specific tumor localization.Our study independently validates PITX2 as a very sensitive and specific immunohistochemical marker of midgut-derived NET in a very large collective of neuroendocrine neoplasms. Therefore, our data argue toward implementation into diagnostic panels applied for NET as a firstline midgut marker.

Specific Tumor Localization of Immunogenic Lipid-Coated Mesoporous Silica Nanoparticles following Intraperitoneal Administration in a Mouse Model of Serous Epithelial Ovarian Cancer.

Immunogenic lipid-coated mesoporous silica nanoparticles (ILM) present pathogen-associated molecular patterns (PAMPs) on the nanoparticle surface to engage pathogen-associated receptors on immune cells. The mesoporous core is capable of loading additional immunogens, antigens or drugs. In this study, the impact of lipid composition, surface potential and intercalation of lipophilic monophosphoryl lipid A (MPL-A) in the lipid coat on nanoparticle properties and cellular interactions is presented. Loading and retention of the model antigen ovalbumin into the mesoporous silica core were found to be similar for all nanoparticle formulations, with presentation of ova peptide (SIINFEKL) by major histocompatibility complex (MHC) evaluated to facilitate the selection of an anionic nanoparticle composition. ILM were able to induce lysosomal tubulation and streaming of lysosomes towards the cell surface in dendritic cells, leading to an enhanced surface presentation of MHC. Myeloid cells robustly internalized all ILM formulations; however, non-myeloid cells selectively internalized cationic ILM in vitro in the presence of 20% serum. Interestingly, ILM administration to the peritoneal cavity of mice with disseminated ovarian cancer resulted in selective accumulation of ILM in tumor-associated tissues (>80%), regardless of nanoparticle surface charge or the presence of MPL-A. Immunofluorescence analysis of the omental tumor showed that ILMs, regardless of surface charge, were localized within clusters of CD11b+ myeloid cells 24 h post administration. Selective uptake of ILMs by myeloid cells in vivo indicates that these cells outcompete other cell populations in the ovarian tumor microenvironment, making them a strong target for therapeutic interventions.

Preclinical radiolabeling, in vivo biodistribution and positron emission tomography of a novel pyrrolobenzodiazepine (PBD)-based antibody drug conjugate targeting ASCT2

IntroductionAnti-ASCT2 antibody drug conjugate (ADC) MEDI7247 has been under development as a potential anti-cancer therapy for patients with selected relapsed/refractory hematological malignancies and advanced solid tumors by MedImmune. Although promising efficacy was observed in the clinic, pharmacokinetic (PK) analyses observed low exposure of MEDI7247 in phase I hematological patients. To investigate the biodistribution properties of MEDI7247, MEDI7247 and control antibodies were radiolabeled with zirconium-89 and in vitro and in vivo properties characterized. MethodsMEDI7247 (human anti-ASCT2 antibody conjugated with pyrrolobenzodiazepine (PBD)) and MEDI7519 (MEDI7247 without PBD drug conjugate) and an isotype control antibody drug conjugate construct were conjugated with p-isothiocyanatobenzyl-deferoxamine (Df) and radiolabeled with zirconium-89. In vitro studies included determining the radiochemical purity, protein integrity, immunoreactivity (Lindmo analysis), apparent antigen binding affinity for ASCT2-positive cells by Scatchard analysis and serum stability of the radiolabeled immunoconjugates. In vivo studies included biodistribution and PET/MRI imaging studies of the radiolabeled immunoconjugates in an ASCT2-positive tumor model, HT-29 colorectal carcinoma xenografts. ResultsConditions for the Df-conjugation and radiolabeling of antibody constructs were determined to produce active radioimmunoconjugates. In vivo biodistribution and whole body PET/MRI imaging studies of [89Zr]Zr-Df-MEDI7519 and [89Zr]Zr-Df-MEDI7247 radioimmunoconjugates in HT-29 colon carcinoma xenografts in BALB/c nude mice demonstrated specific tumor localization. However, more rapid blood clearance and non-specific localization in liver was observed for [89Zr]Zr-Df-MEDI7247 and [89Zr]Zr-Df-MEDI7519 compared to isotype control ADC. Except for liver and bone, other normal tissues demonstrated clearance reflecting the blood clearance for all three constructs and no other abnormal tissue uptake. Conclusions and advances in knowledgePreclinical biodistribution analyses of [89Zr]Zr-Df-MEDI7247 and [89Zr]Zr-Df-MEDI7519 showed the biodistribution pattern of anti-ASCT2 ADC MEDI7247 was similar to parental MEDI7519, and both antibodies showed specific tumor uptake compared to an isotype control ADC. This study highlights an important role nuclear medicine imaging techniques can play in early preclinical assessment of drug specificity as part of the drug development pipeline.

IL12 immune therapy clinical trial review: Novel strategies for avoiding CRS-associated cytokines.

Interleukin 12 (IL-12) is a naturally occurring cytokine that plays a key role in inducing antitumor immune responses, including induction of antitumor immune memory. Currently, no IL-12-based therapeutic products have been approved for clinical application because of its toxicities. On the basis of this review of clinical trials using primarily wild-type IL-12 and different delivery methods, we conclude that the safe utilization of IL-12 is highly dependent on the tumor-specific localization of IL-12 post administration. In this regard, we have developed a cell membrane-anchored and tumor-targeted IL-12-T (attIL12-T) cell product for avoiding toxicity from both IL-12 and T cells-induced cytokine release syndrome in peripheral tissues. A phase I trial using this product which seeks to avoid systemic toxicity and boost antitumor efficacy is on the horizon. Of note, this product also boosts the impact of CAR-T or TCR-T cell efficacy against solid tumors, providing an alternative approach to utilize CAR-T to overcome tumor resistance.

Targeting a proteolytic neoepitope on CUB domain containing protein 1 (CDCP1) for RAS-driven cancers.

Extracellular proteolysis is frequently dysregulated in disease and can generate proteoforms with unique neoepitopes not found in healthy tissue. Here, we demonstrate that Abs that selectively recognize a proteolytic neoepitope on CUB domain containing protein 1 (CDCP1) could enable more effective and safer treatments for solid tumors. CDCP1 is highly overexpressed in RAS-driven cancers, and its ectodomain is cleaved by extracellular proteases. Biochemical, biophysical, and structural characterization revealed that the 2 cleaved fragments of CDCP1 remain tightly associated with minimal proteolysis-induced conformational change. Using differential phage display, we generated recombinant Abs that are exquisitely selective to cleaved CDCP1 with no detectable binding to the uncleaved form. These Abs potently targeted cleaved CDCP1-expressing cancer cells as an Ab-drug conjugate, an Ab-radionuclide conjugate, and a bispecific T cell engager. In a syngeneic pancreatic tumor model, these cleaved-specific Abs showed tumor-specific localization and antitumor activity with superior safety profiles compared with a pan-CDCP1 approach. Targeting proteolytic neoepitopes could provide an orthogonal “AND” gate for improving the therapeutic index.

BIMG-18. ELEVATED CYSTATHIONINE IN MEDULLOBLASTOMA DEMONSTRATES TUMOR-SPECIFIC METHIONINE METABOLISM

We investigated tumor-specific metabolism medulloblastoma using a non-biased MS-imaging screen and identified a pattern of methionine flux that may present a therapeutic opportunity. We studied brain tumors that form in mice genetically engineered to develop Sonic Hedgehog (SHH)-driven medulloblastoma. We subjected sagittal sections including brain and medulloblastoma to MS-imaging, generating concentration maps for hundreds of metabolites MW 100–400. We then confirmed results by analyzing tumor, brain and blood by LC-MS/MS, high-resolution NMR and 2D NMR-TOCSY, and used immunohistochemistry to determine the cellular localization of implicated enzymes. MS imaging, accomplished by matrix-assisted laser desorption electrospray ionization (MALDESI), detected cystathionine at an order of magnitude higher concentration in medulloblastomas compared to adjacent brain. No other metabolite showed such a strong, tumor-specific localization. LC-MS/MS and NMR methods confirmed cystathionine elevation. As cystathionine is the product of homocysteine and serine, catalyzed by cystathionine beta-synthase (CBS), we investigated CBS expression by IHC. Consistent with prior studies, we found that only astrocytes expressed CBS, both in the normal brain and within the tumors. ScRNA-seq confirmed Cbs only in astrocytes, and showed tumor cells express methionine-metabolizing enzymes Mat2a, Dnmt1, Ancy and Mtr. Together, these findings show that tumor cells generate and export homocysteine, which astrocytes convert to cystathionine. Tumor cystathionine generation responded to changes in methionine- cycle metabolites. In vivo, systemic administration of homocysteine increased tumor cystathionine which decreased in response to systemic folate, the methyl donor for homocysteine methyltransferase. Cystathionine itself was inert in tumors as tumor cells cultured in up to 8 mM cystathionine showed no change in cell cycle progression. Our studies show that medulloblastomas utilize methionine and generate homocysteine, but avoid folate-dependent homocysteine-methionine recycling by exporting homocysteine for detoxification by local astrocytes. This model suggests that treatments that impose methionine scarcity, folate scarcity or CBS inhibition may produce anti-tumor effects in medulloblastoma.

Recent Advancements in Stimuli Responsive Drug Delivery Platforms for Active and Passive Cancer Targeting.

Simple SummaryCancer is one of the leading causes of death globally. Several studies, efforts and treatment strategies have been put forth for the treatment of different types of cancers. Several chemotherapeutic agents have been discovered and utilized for the treatment of various types of cancers and tumors, which play an important role in improving the quality of life of patients. The key problems associated with the abovementioned chemotherapeutic agents are the limited target ability and non-selective toxicity. The current review focuses on the achievement of improved targeting of anticancer agents at the tumor microenvironment without affecting normal tissues. The fulfilment of the mentioned objectives by stimuli-responsive drug delivery systems, as physical stimuli-responsive drug delivery systems and chemical stimuli-responsive drug delivery systems through active and passive targeting have extensively been discussed in the current review. The current review will help the wide community of researchers conducting research in targeted drug delivery systems and anticancer treatment strategies.The tumor-specific targeting of chemotherapeutic agents for specific necrosis of cancer cells without affecting the normal cells poses a great challenge for researchers and scientists. Though extensive research has been carried out to investigate chemotherapy-based targeted drug delivery, the identification of the most promising strategy capable of bypassing non-specific cytotoxicity is still a major concern. Recent advancements in the arena of onco-targeted therapies have enabled safe and effective tumor-specific localization through stimuli-responsive drug delivery systems. Owing to their promising characteristic features, stimuli-responsive drug delivery platforms have revolutionized the chemotherapy-based treatments with added benefits of enhanced bioavailability and selective cytotoxicity of cancer cells compared to the conventional modalities. The insensitivity of stimuli-responsive drug delivery platforms when exposed to normal cells prevents the release of cytotoxic drugs into the normal cells and therefore alleviates the off-target events associated with chemotherapy. Contrastingly, they showed amplified sensitivity and triggered release of chemotherapeutic payload when internalized into the tumor microenvironment causing maximum cytotoxic responses and the induction of cancer cell necrosis. This review focuses on the physical stimuli-responsive drug delivery systems and chemical stimuli-responsive drug delivery systems for triggered cancer chemotherapy through active and/or passive targeting. Moreover, the review also provided a brief insight into the molecular dynamic simulations associated with stimuli-based tumor targeting.

Peptide functionalized liposomes for receptor targeted cancer therapy.

Most clinically approved cancer therapies are potent and toxic small molecules that are limited by severe off-target toxicities and poor tumor-specific localization. Over the past few decades, attempts have been made to load chemotherapies into liposomes, which act to deliver the therapeutic agent directly to the tumor. Although liposomal encapsulation has been shown to decrease toxicity in human patients, reliance on passive targeting via the enhanced permeability and retention (EPR) effect has left some of these issues unresolved. Recently, investigations into modifying the surface of liposomes via covalent and/or electrostatic functionalization have offered mechanisms for tumor homing and subsequently controlled chemotherapeutic delivery. A wide variety of biomolecules can be utilized to functionalize liposomes such as proteins, carbohydrates, and nucleic acids, which enable multiple directions for cancer cell localization. Importantly, when nanoparticles are modified with such molecules, care must be taken as not to inactivate or denature the ligand. Peptides, which are small proteins with <30 amino acids, have demonstrated the exceptional ability to act as ligands for transmembrane protein receptors overexpressed in many tumor phenotypes. Exploring this strategy offers a method in tumor targeting for cancers such as glioblastoma multiforme, pancreatic, lung, and breast based on the manifold of receptors overexpressed on various tumor cell populations. In this review, we offer a comprehensive summary of peptide-functionalized liposomes for receptor-targeted cancer therapy.

Bacillus anthracis Protective Antigen Shows High Specificity for a UV Induced Mouse Model of Cutaneous Squamous Cell Carcinoma.

Squamous cell carcinoma (SCC) accounts for the majority of non-melanoma skin cancer related deaths, particularly in immunosuppressed persons. Identification of biomarkers that could be used to identify or treat SCC would be of significant benefit. The anthrax toxin receptors, Tumor Endothelial Marker 8 (TEM8) and Capillary Morphogenesis Gene 2 (CMG2), are endothelial receptors involved in extracellular matrix homeostasis and angiogenesis that are selectively upregulated on numerous tumors. One method of targeting these receptors is Protective Antigen (PA), a protein produced by B. anthracis that mediates binding and translocation of anthrax toxins into cells. PA targeted toxins have been demonstrated to selectively inhibit tumor growth and angiogenesis, but tumor selectivity of PA is currently unknown. In this work fluorescently labeled PA was shown to maintain receptor dependent binding and internalization in vitro. Utilizing a human papillomavirus transgenic mouse model that develops cutaneous SCC in response to ultraviolet irradiation we identified tumor uptake of PA in vivo. The intravenously administered PA resulted in tumor specific localization, with exclusive tumor detection 24 h post injection. Ex vivo analysis identified significantly higher fluorescence in the tumor compared to adjacent healthy tissue and major clearance organs, demonstrating low non-specific uptake and rapid clearance. While both TEM8 and CMG2 were observed to be overexpressed in SCC tumor sections compared to control skin, the intravenously administered PA was primarily co-localized with TEM8. These results suggest that PA could be systemically administered for rapid identification of cutaneous SCC, with potential for further therapeutic development.

Abstract 2024: Hyaluronic acid conjugated nanoparticle delivery of siTWIST reduces tumor burden and enhances chemosensitivity in ovarian cancer

Abstract Purpose: TWIST is a transcription factor critical to embryonic development, and aberrantly activated in many cancers. It regulates epithelial-to-mesenchymal transition (EMT), the process underlying metastatic spread and drug resistance. The majority of epithelial ovarian cancer (EOC) patients respond well to chemotherapy, but relapse with metastatic and drug-resistant disease. We are investigating the role of TWIST-mediated relapse, with the goal of developing treatments that sensitize chemoresistant tumors and improve survival. Experimental Procedures: We employ siRNA to target TWIST mRNA and have created a mesoporous silica nanoparticle with hyaluronic acid (siTWIST-MSN-HA) as a delivery vehicle. Microscopy was conducted to ensure cancer stem cell (CSC) targeting via CD44, and efficient uptake of MSN-HAs. We tested TWIST knockdown combined with cisplatin in vitro and in vivo. At necropsy, total tumor, metastasis, and ascites were evaluated to determine effects of siTWIST-MSN-HA compared to cisplatin alone. qPCR was conducted on tumors to examine effect of siRNA against TWIST, and its target genes. Mice were imaged via bioluminescence to observe CSC localization of siTWIST-MSN-HA compared to siTWIST-MSN (No HA). Tissue sections were stained via IHC to determine MSN-HA tumor targeting. CD44 staining was conducted to reveal HA co-localization in tumor. Results: siTWIST-MSN-HAs significantly knocked down TWIST, and sensitized cells to cisplatin compared to control in vitro. Following necropsy, tumor quantification revealed mice treated with siTWIST-MSN-HAs plus cisplatin exhibited a startling 75% loss of overall tumor burden (p=0.0012), 88% loss of total metastasis (p=0.001), and further 86% loss of total ascites (p=0.002) compared to cisplatin-alone treatment groups. EMT target expression by qPCR analysis revealed loss of TWIST1, vimentin, N-cadherin, and gain of E-cadherin in tumors treated with siTWIST-MSN-HA compared to controls. Bioluminescent images of mice at necropsy revealed highly specific tumor localization of MSN-HA Dylight (680nm) compared to MSN without HA. MSN-HA exhibited CSC targeting at metastatic sites, where most of the signal was emitted from the primary tumor; and negligible quantities of MSN-HAs were detected elsewhere. MSN-HA RITC (576nm) reveals highly specific tumor targeting via IHC; MSN-HA nanoparticles localized primarily in tumor cells and not in control organs. CD44 staining of these tissues reveals MSN-HAs co-localized with CD44 in CSCs. Conclusions: These studies demonstrate TWIST as a promising target for metastasis and acquired drug resistance in EOC. MSN-HAs provide CSC specific CD44 targeting with high efficacy and reduce tumor burden via siTWIST therapy. Thus, siTWIST-MSN-HAs provide a promising platform to improve survival from metastatic, drug-resistant ovarian cancer. Citation Format: Carlotta A. Glackin, Sophia A. Shahin, Shirleen Simargi, Ruining Wang, Altagracia Contreras, Liliana Parra, Loiuse Qu, Wei Wen, Thanh Dellinger, Julia Unternaehrer, Fuyujiko Tamanoi, Jeffrey Zink. Hyaluronic acid conjugated nanoparticle delivery of siTWIST reduces tumor burden and enhances chemosensitivity in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2024.

Abstract 1831: PET/CT imaging of interleukin-13 receptor alpha-2-targeted peptide to glioblastoma after locoregional delivery

Abstract Glioblastoma (GBM) is the most aggressive and common primary malignant astrocytoma which is characterized by tumor heterogeneity, infiltrating margins. Radiotherapy, chemotherapy and experimental targeted therapies have been ineffective at meaningfully increasing patient survival. One significant shortcoming of systemically delivered therapies is their inability to cross the blood brain barrier (BBB) and access infiltrating tumor cells. Therefore, in this work, we tested the potential of locoregionally targeting GBM via IL13Rα2, which we discovered to be expressed on greater than 75% of GBMs. To accomplish this, we intracranially infused copper-64 (64Cu) radiolabeled IL13Rα2 specific peptide Pep-1L, previously developed by Pandya et al., into mice bearing IL13Rα2 expressing orthotopic GBMs. Small animal micro PET/CT imaging showed ~2-fold greater tumor specific localization and lower volume of distribution of 64Cu-Pep-1L within brains of mice. Post-PET biodistribution study showed greater retention of 64Cu-Pep-1L 4 hours (%ID/g = 20.85± 0.65) and 24 hours (%ID/g = 14.65± 0.30) post infusion when compared to similarly infused 64Cu radiolabeled scrambled control peptide 4 hours (%ID/g = 10.73± 2.02) and 24 hours (%ID/g = 5.97± 1.47) post infusion. These results demonstrate that Pep-1L efficiently targets IL13Rα2 expressing GBMs in vivo upon loco-regional delivery and can effectively deliver potential therapeutic agents to GBM tumors while sparing normal brain. This work was supported by the American Cancer Society Mentored Research Scholar grant # 124443-MRSG-13-121-01-CDD (Mintz), 1R01CA179072-01A1 (Mintz), P30 CA012197 (Pasche), R01CA07414519 (Debinski) and the Translational Imaging Program (TIP) of the Wake Forest CTSA (UL1TR001420). Citation Format: Anirudh Sattiraju, Ang Xuan, Frankis Almaguel, Denise Herpai, Waldemar Debinski, Akiva Mintz, Kiran Kumar Solingapuram Sai. PET/CT imaging of interleukin-13 receptor alpha-2-targeted peptide to glioblastoma after locoregional delivery [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1831. doi:10.1158/1538-7445.AM2017-1831

Non-Melanoma Skin Cancers of the Fronto-Temporal Area Preferentially Localize in the Proximity of Arterial Blood Vessels

Background: Squamous cell carcinomas and basal cell carcinomas are both induced by chronic UV exposure. However, their predilection for specific areas of the face remains unexplained. Regional factors such as arterial blood flow may explain specific tumor localization. Objective: To determine whether in the fronto-temporal area of the face there is a preferential localization of non-melanoma skin cancer (NMSC) at sites of arterial blood vessels. Methods: Twenty-two patients with NMSC of the fronto-temporal area were selected for this study. The clinical tumor margins were demarked based on clinical examination. Arterial colocalization was determined using both sonography and histological analysis. Results: Echo-Doppler analysis revealed the colocalization of NMSC with an arterial branch in 59% of the patients. Histologically, colocalization between NMSC and artery was found in 68% of the patients. When combining echo-Doppler and histological results, colocalization of NMSC and arteries were found in 82% of the patients. Conclusion: In this study, we found an unexpectedly high colocalization of NMSC with arterial branches in the fronto-temporal area of the face. These results suggest that in addition to UV exposure, pulsatile arterial blood flow may represent an additional factor determining the precise facial localization of NMSC.

Hypoxia-directed and activated theranostic agent: Imaging and treatment of solid tumor.

Hypoxia, a distinguished feature of various solid tumors, has been considered as a key marker for tumor progression. Inadequate vasculature and high interstitial pressures result in relatively poor drug delivery to these tumors. Herein, we developed an antitumor theranostic agent, 4, which is activated in hypoxic conditions and can be used for the diagnosis and treatment of solid tumors. Compound 4, bearing biotin, a tumor-targeting unit, and SN38, an anticancer drug, proved to be an effective theranostic agent for solid tumors. SN38 plays a dual role: as an anticancer drug for therapy and as a fluorophore for diagnosis, thus avoids an extra fluorophore and limits cytotoxicity. Compound 4, activated in the hypoxic environment, showed high therapeutic activity in A549 and HeLa cells and spheroids. Invivo imaging of solid tumors confirmed the tumor-specific localization, deep tissue penetration and activation of compound 4, as well as the production of a strong anticancer effect through the inhibition of tumor growth in a xenograft mouse model validating it as a promising strategy for the treatment of solid tumors.

Multifunctional platinum-based nanoparticles for biomedical applications.

Platinum-based anticancer drugs play a central role in current cancer therapy. However, their applicability and efficacy are limited by drug resistance and adverse effects. Nanocarrier-based platinum drug delivery systems are promising alternatives to circumvent the disadvantages of bare platinum drugs. The various properties of nanoparticle chemistry allow for the trend toward multiple functionality. Nanoparticles preferentially accumulate at the tumor site through passive targeting, and the attachment of tumor targeting moieties further enhances their tumor-specific localization as well as tumor cell uptake. The introduction of stimuli-responsive groups into drug delivery systems can further achieve spatially and temporally controlled drug release in response to specific stimuli. Combination therapy strategies have been used to promote synergetic efficacy and overcome the resistance of platinum drugs. The tumor-localized drug delivery strategies exhibit benefits for preventing local tumor recurrence. In addition, the combination of platinum drugs and imaging agents in one unity allows the cancer diagnostics for real-time monitoring the distribution of drug-loaded nanoparticles inside the body and tumor. This review discusses recent scientific advances in multifunctional nanoparticle formulations of platinum drugs, and these designs exhibit new potential of multifunctional nanoparticles for delivering platinum-based anticancer drugs. WIREs Nanomed Nanobiotechnol 2017, 9:e1410. doi: 10.1002/wnan.1410 For further resources related to this article, please visit the WIREs website.

Monoclonal Antibody against Cell Surface GRP78 as a Novel Agent in Suppressing PI3K/AKT Signaling, Tumor Growth, and Metastasis

The ER chaperone GRP78 translocates to the surface of tumor cells and promotes survival, metastasis, and resistance to therapy. An oncogenic function of cell surface GRP78 has been attributed to the activation of the phosphoinositide 3-kinase (PI3K) pathway. We intend to use a novel anti-GRP78 monoclonal antibody (MAb159) to attenuate PI3K signaling and inhibit tumor growth and metastasis. MAb159 was characterized biochemically. Antitumor activity was tested in cancer cell culture, tumor xenograft models, tumor metastasis models, and spontaneous tumor models. Cancer cells and tumor tissues were analyzed for PI3K activity. MAb159 was humanized and validated for diagnostic and therapeutic application. MAb159 specifically recognized surface GRP78, triggered GRP78 endocytosis, and localized to tumors but not to normal organs in vivo. MAb159 inhibited tumor cell proliferation and enhanced tumor cell death both in vitro and in vivo. In MAb159-treated tumors, PI3K signaling was inhibited without compensatory MAPK pathway activation. Furthermore, MAb159 halted or reversed tumor progression in the spontaneous PTEN-loss-driven prostate and leukemia tumor models, and inhibited tumor growth and metastasis in xenograft models. Humanized MAb159, which retains high affinity, tumor specific localization, and the antitumor activity, was nontoxic in mice, and had desirable pharmacokinetics. GRP78-specific antibody MAb159 modulates the PI3K pathway and inhibits tumor growth and metastasis. Humanized MAb159 will enter human trials shortly.

Hyaluronate Tethered, “Smart” Multiwalled Carbon Nanotubes for Tumor-Targeted Delivery of Doxorubicin

The present study reports the optimized synthesis, physicochemical characterization, and biological evaluation of a novel, multiwalled carbon nanotube-hyaluronic acid (MWCNT-HA) conjugate, complexed with an anticancer agent, Doxorubicin (DOX) via π-π stacking interaction. The therapeutic conjugate was concomitantly labeled with a near-infrared fluorescent dye, Alexa-Flour-647 (AF-647), and radiotracer Technetium-99m ((99m)Tc) to track its whereabouts both in vitro and in vivo via optical and scintigraphic imaging techniques. Covalent functionalization of MWCNTs with HA facilitated their internalization into human lung adenocarcinoma, A549 cells via hyaluronan receptors (HR) mediated endocytosis. Internalized nanotubes showed lysosomal trafficking, followed by low pH-triggered DOX release under endolysosomal conditions. Consequently, DOX-loaded HA-MWCNTs exhibited 3.2 times higher cytotoxicity and increased apoptotic activity than free DOX in equivalent concentrations. Organ distribution studies in Ehlrich ascites tumor (EAT) bearing mice model indicated that tumor specific localization of (99m)Tc-MWCNT-HA-DOX is significantly higher than both free drug and nontargeted MWCNTs. Pharmacodynamic studies in chemically breast-cancer-induced rats showed that the tumor-growth inhibitory effect of HA-MWCNT-DOX was 5 times higher than free DOX in equivalent concentration. DOX delivered through HA-MWCNTs was devoid of any detectable cardiotoxity, hepatotoxicity, or nephrotoxicity. All these promising attributes make HA-MWCNTs a "smart" platform for tumor-targeted delivery of anticancer agents.

Synthesis, Pharmacoscintigraphic Evaluation and Antitumor Efficacy of Methotrexate-Loaded, Folate-Conjugated, Stealth Albumin Nanoparticles

The present study aims to develop a multifunctional nanoformulation based on technetium-99m labeled, folate conjugated, methotrexate-loaded human serum albumin nanoparticles (HSA NPs) and explore their potential in cancer theragnostics. Methotrexate-loaded HSA NPs were synthesized by a reverse microemulsion technique, followed by chemical crosslinking with glutaraldehyde. These NPs were conjugated with folic acid (FA) through a hydrophilic polyethylene glycol spacer to render them long-circulatory and augment their tumor-specific localization. The therapeutic conjugate was further radiolabeled with a γ-emitter technetium-99m for real-time monitoring of its blood clearance kinetics and biodistribution through the measurement of blood/organ-associated radioactivity and scintigraphic imaging. In vitro cell-uptake and cytotoxicity studies corroborated that FA conjugation enabled these NPs to specifically target and kill folate-receptor overexpressing cancer cells via S phase arrest. Blood clearance kinetics and biodistribution studies clearly indicated that circulation time, as well as tumor-specific localization of methotrexate-loaded HSA nanocarriers, could be significantly augmented upon polyethylene glycolylation and conjugation of FA. Finally, we demonstrated that these targeted HSA NPs inhibited tumor growth more effectively, as compared with the nontargeted controls.

Abstract B112: Personalizing anti-IL13R 2 therapy with real-time immunoPET visualization of biomarker expression.

Abstract Interleukin 13 Receptor 2 (IL13R 2) is a tumor-restricted plasma membrane receptor that is overexpressed on greater than 70% of Glioblastoma Multiformes (GBM) as well as in other malignancies, including melanoma, adenocarcinoma, ovarian cancer and renal cell carcinoma. We and others have therapeutically exploited this attractive tumor-restricted biomarker in a number of ways, including with bacterial toxins, chemotherapeutics, nanoparticles, viruses and immunotherapies. Our objective here is to for the first time develop a positron emission tomography (PET)-based molecular imaging probe that can non-invasively visualize IL13R 2 expression in order to determine if it is expressed on a particular patient's tumor, which can then potentially be therapeutically targeted. To accomplish our goal, we created a novel IL13R 2-Targeted Quadruple Mutant of IL13 (TQM13; IL13.E13K/R66D/S69D/K105R) based on our prior work in which we identified functional “hotspot” amino acid mutations of IL13 that separately increased its affinity towards the tumor-restricted IL13R 2 but abrogated its binding to the physiologically abundant IL13R 1/IL4R heterodimer. In addition, we created a matching negative control, IL13R-Binding Deficient mutant (BDef13; IL13.E13K/R66D/S69D/K105A) with disrupted binding to both IL13R 1 and IL13R 2. In these experiments, our goals were to confirm the binding profile of this optimized ligand in vitro and its potential as a non-invasive PET probe to visualize the cancer-restricted IL13R 2 biomarker in vivo. We demonstrated that 125I-TQM13, but not 125I-BDef13, specifically bound to IL13R 2 via autoradiography on frozen GBM sections and electrophoretic mobility shift assay. An in vitro cell binding assay confirmed 125I-TQM13 had strong affinity to IL13R 2-expressing cells (Kd ∼ 5nM). This binding assay also established that G48a GBM cell line, which we utilized in our in vivo studies, highly expressed IL13R 2 with approximately three million binding sites per cell. Importantly, in an in vivo biodistribution study, 125I-TQM13 bound to IL13R 2-expressing G48a tumors at a 7-to-1 ratio compared to background muscles 24 hours after intravenous injection, in contrast to 125I-BDef13, which remained at background levels. We therefore radiolabeled TQM13 with the positron emitter 124I and intravenously delivered it to mice bearing subcutaneous G48a tumors. Subsequent microPET images at 24 and 48 hours post-injection demonstrated specific tumor localization with tumor-to-background ratio of 7:1 at 48 hours. In contrast, 124I-BDef13 only demonstrated background signal levels. In conclusion, we have successfully generated an optimized, biomarker-targeted IL13 derivative and demonstrated for the first time the potential to non-invasively image the attractive cancer-restricted biomarker, IL13R 2. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B112.

Only a single implanted marker is needed for tracking lung cancers for IGRT

Only a single implanted marker is needed for tracking lung cancers for IGRT