Fluorinated EuII-based multimodal contrast agent for temperature- and redox-responsive magnetic resonance imaging

Magnetic resonance imaging (MRI) using redox-active, EuII-containing complexes is one of the most promising techniques for noninvasively imaging hypoxia in vivo. In this technique, positive (T1-weighted) contrast enhancement persists in areas of relatively low oxidizing ability, such as hypoxic tissue. Herein, we describe a fluorinated, EuII-containing complex in which the redox-active metal is caged by intramolecular interactions. The position of the fluorine atoms enables temperature-responsive contrast enhancement in the reduced form of the contrast agent and detection of the oxidized contrast agent via MRI in vivo. Positive contrast is observed in 1H-MRI with Eu in the +2 oxidation state, and chemical exchange saturation transfer and 19F-MRI signal are observed with Eu in the +3 oxidation state. Contrast enhancement is controlled by the redox state of Eu, and modulated by the fluorous interactions that cage a bound water molecule reduce relaxivity in a temperature-dependent fashion. Together, these advancements constitute the first report of in vivo, redox-responsive imaging using 19F-MRI.

Effect of locally tailored labour management guidelines on intrahospital stillbirths and birth asphyxia at the referral hospital of Zanzibar: a quasi-experimental pre-post study (The PartoMa study)

OBJECTIVE

To evaluate effect of locally tailored labour management guidelines (PartoMa guidelines) on intrahospital stillbirths and birth asphyxia.

DESIGN

Quasi-experimental pre-post study investigating the causal pathway through changes in clinical practice.

SETTING

Tanzanian low-resource referral hospital, Mnazi Mmoja Hospital.

POPULATION

Facility deliveries during baseline (1 October 2014 until 31 January 2015) and the 9th to 12th intervention month (1 October 2015 until 31 January 2016) [corrected].

METHODS

Birth outcome was extracted from all cases of labouring women during baseline (n = 3690) and intervention months (n = 3087). Background characteristics and quality of care were assessed in quasi-randomly selected subgroups (n = 283 and n = 264, respectively).

MAIN OUTCOME MEASURES

Stillbirths and neonates with 5-minute Apgar score ≤5.

RESULTS

Stillbirth rate fell from 59 to 39 per 1000 total births (RR 0.66, 95% CI 0.53-0.82), and subanalyses suggest that this was primarily due to reduction in intrahospital stillbirths. Apgar scores between 1 and 5 fell from 52 to 28 per 1000 live births (RR 0.53, 95% CI 0.41-0.69). Median time from last fetal heart assessment till delivery (or fetal death diagnosis) fell from 120 minutes (IQR 60-240) to 74 minutes (IQR 30-130) (Mann-Whitney test for difference, P < 0.01). Oxytocin augmentation declined from 22% to 12% (RR 0.54, 95% CI 0.37-0.81) and timely use improved.

CONCLUSION

Although low human resources and substandard care remain major challenges, PartoMa guidelines were associated with improvements in care, leading to reductions in stillbirths and birth asphyxia. Findings furthermore emphasise the central role of improved fetal surveillance and restricted intrapartum oxytocin use in safety at birth. TWEETABLE ABSTRACT: #PartoMa guidelines aided in reducing stillbirths and birth asphyxia at a Tanzanian low-resource hospital PLAIN LANGUAGE SUMMARY: PartoMa guidelines help birth attendants in Tanzania to save lives Every year, 3 million babies die on the day of birth. The vast majority of these deaths occur in the poorest countries. If their mothers had received better care during birth, most babies would have survived. At Mnazi Mmoja Hospital, an East African referral hospital, the PartoMa study shows that use of locally developed guidelines helps birth attendants to deliver better quality of care, which has led to improved survival at birth. At the hospital studied, resources are scarce. Each birth attendant assists four to six birthing women simultaneously, and many have less than 1 year of professional experience. International guidelines are available, but they are often unachievable and seldom applied. The PartoMa guidelines were developed in close collaboration with the birth attendants and approved by seven international experts. The result is an 8-page pocket booklet providing locally achievable and simple decision support for care during birth. Use of the PartoMa guidelines began in February 2015. As the staff group frequently changes, quarterly seminars are conducted where birth attendants are welcomed after working hours to learn about the guidelines. The guidelines have been positively received, and seminar attendance remains high. Use of the PartoMa guidelines is associated with: A decrease by one-third in stillbirths (59 to 39 per 1000 total births) A nearly halving in the number of babies born in immediate poor medical condition (52 to 28 per 1000 live births) The results presented here derive from a comparison of births before using the PartoMa guidelines and during the 9th-12th month of use. Such a 'before-after' study cannot exclude the possibility of other causes of better survival at birth. However, the improved survival is consistent with improved care during birth, which is in line with the PartoMa guidelines.

Abstract 2184: Development and testing of nanoformulation of a vascular disrupting agent in rat glioma with MRI monitoring

Anti-angiogenesis therapy VEGF-VEGF receptors (VEGFRs) axis alone or in combination with other therapeutic agents have demonstrated mixed results, with the majority of reports indicating that glioblastoma multiform (GBM) developed resistance against anti-angiogenesis therapy as well as small molecular receptor tyrosine kinase inhibitors. This result is perhaps not unexpected, because angiogenesis is obviously complex, involving dozen of different growth factors that trigger a cascade of subsequent events. Even if a drug effectively blocks one angiogenic growth factor, such as VEGF, blood vessels may still develop via activating alternative pathways. Yet without a sufficient blood supply, cancerous tumors can't grow larger than the head of a pin and are unlikely to become lethal. Therefore, tumor vascularization is a critical process that determines tumor growth, progression and metastasis. Thus, tumor vasculature has become an emerging target for new chemotherapeutic drugs Vascular disrupting agents (VDAs) for example, combretastatin (CA4), represent a new class of chemotherapeutic agent that targets the newly formed vasculature in solid tumors. Preclinical and early phase trials have demonstrated the promising therapeutic benefits of CA4. Nevertheless, the clinical translation of CA4 has been significantly hampered due to its poor systemic bioavailability and the non-specific distribution of CA4 throughout the body when administered intravenously. Thus, it is reasonable to explore novel formulations of CA4 that overcome the limitations mentioned above. To improve bioavailability combretastatin phosphate (CA4-P) has been synthesized. But, CA4-P showed short blood half life. We have engineered dendrimer-based nano-sized CA4 conjugate which demonstrates high water solubility. Preliminary intravenous (i.v.) delivery of nano-combretastatin in an orthotropic glioma model demonstrated a necrosis at the core of the tumor leaving a rim of viable tissue. The MRI-determined tissue parameters Ktrans, blood flow (CBF), DWI, ADC map, distribution volume and tumor size indicated the effectiveness of nano-combretastatin treatment.

Citation Format: Meser M. Ali, Sunalee Jayasundara, James R. Ewing. Development and testing of nanoformulation of a vascular disrupting agent in rat glioma with MRI monitoring [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 2184. doi:10.1158/1538-7445.AM2017-2184

Application of Dendrimer-based Nanoparticles in Glioma Imaging

Dendritic polymers or dendrimers present an alternate template for the development of nanoparticulate-based drug delivery and imaging systems. The smaller size (~7-12 nm) of dendrimers have the advantage over the other particles, because its smaller size can possibly improve tumor penetration and the inclusion of tumor specific drug release mechanisms. A Paramagnetic Chemical Exchange Saturation Transfer (PARACEST) MRI contrast agent, Eu-DOTA-Gly4 or a clinical relevant Gd-DOTA was conjugated on the surface of a G5 PAMAM dendrimer. To create a dual mode MRI-optical imaging nanoparticle, Dylight680 was also incorporated on the amines surface of a G5 dendrimer. The particle was detected with in vivo MRI in preclinical glioma animal model. Furthermore, noninvasive imaging results were validated with in vivo and ex-vivo optical imaging.

MicroRNA cluster miR-17-92 Cluster in Exosomes Enhance Neuroplasticity and Functional Recovery After Stroke in Rats

BACKGROUND AND PURPOSE

Multipotent mesenchymal stromal cell (MSC) harvested exosomes are hypothesized as the major paracrine effectors of MSCs. In vitro, the miR-17-92 cluster promotes oligodendrogenesis, neurogenesis, and axonal outgrowth. We, therefore, investigated whether the miR-17-92 cluster-enriched exosomes harvested from MSCs transfected with an miR-17-92 cluster plasmid enhance neurological recovery compared with control MSC-derived exosomes.

METHODS

Rats subjected to 2 hours of transient middle cerebral artery occlusion were intravenously administered miR-17-92 cluster-enriched exosomes, control MSC exosomes, or liposomes and were euthanized 28 days post-middle cerebral artery occlusion. Histochemistry, immunohistochemistry, and Golgi-Cox staining were used to assess dendritic, axonal, synaptic, and myelin remodeling. Expression of phosphatase and tensin homolog and activation of its downstream proteins, protein kinase B, mechanistic target of rapamycin, and glycogen synthase kinase 3β in the peri-infarct region were measured by means of Western blots.

RESULTS

Compared with the liposome treatment, both exosome treatment groups exhibited significant improvement of functional recovery, but miR-17-92 cluster-enriched exosome treatment had significantly more robust effects on improvement of neurological function and enhancements of oligodendrogenesis, neurogenesis, and neurite remodeling/neuronal dendrite plasticity in the ischemic boundary zone (IBZ) than the control MSC exosome treatment. Moreover, miR-17-92 cluster-enriched exosome treatment substantially inhibited phosphatase and tensin homolog, a validated miR-17-92 cluster target gene, and subsequently increased the phosphorylation of phosphatase and tensin homolog downstream proteins, protein kinase B, mechanistic target of rapamycin, and glycogen synthase kinase 3β compared with control MSC exosome treatment.

CONCLUSIONS

Our data suggest that treatment of stroke with tailored exosomes enriched with the miR-17-92 cluster increases neural plasticity and functional recovery after stroke, possibly via targeting phosphatase and tensin homolog to activate the PI3K/protein kinase B/mechanistic target of rapamycin/glycogen synthase kinase 3β signaling pathway.

Abstract 156: Tailored Multipotent Mesenchymal Stromal Cell Harvested Exosomes Carrying Elevated miR-17-92 Cluster Enhance Neurovascular Remodeling & Improve Functional Recovery After Stroke in Rats

Introduction: MSC generated exosomes mediate therapeutic benefits of MSCs for stroke, which are at least in-part attributed to their miRNA contents. In vitro, the miR-17-92 cluster promotes oligodendrogenesis, neurogenesis and axonal outgrowth, and tailored MSC exosomes enriched with the miR-17-92 cluster promote axonal outgrowth of primary cortical neurons. We therefore investigated whether the miR-17-92 cluster enriched exosomes (Exo-miR-17-92 + ) harvested from MSCs enhance neurological recovery compared to control MSC derived exosomes (Exo-Con).

Methods: Rats (n=8/group) subjected to 2 hours of transient MCAO were intravenously administered Exo-miR-17-92 + , Exo-Con, or liposomes, and were sacrificed 28 days post MCAO. Foot-fault test, and a modified neurologic severity score (mNSS) were carried out at 1, 3, 7, 14, 21 and 28 days after MCAO by an investigator blinded to the treatments. Histochemistry, immunohistochemistry and Golgi-Cox staining were used to assess dendritic, axonal, synaptic and myelin remodeling. Expression of PTEN and activation of its downstream proteins, Akt, mTOR and GSK-3β in the peri-infarct region were measured by means of Western blots.

Results: Compared with the liposome treatment, both exosome treatment groups exhibited significant improvement of functional recovery (P<0.05, respectively), but Ex-miR-17-92 + treatment had more robust effects on improvement of neurological function (P<0.05), and enhancements of oligodendrogenesis, neurogenesis and neurite remodeling/neuronal dendrite plasticity in the ischemic boundary zone (IBZ) than the Ex-Con treatment (P<0.05, respectively). Moreover, Ex-miR-17-92 + treatment substantially inhibited PTEN, a validated miR-17-92 cluster target gene, and subsequently increased the phosphorylation of PTEN downstream proteins, Akt, mTOR, and decreased the activity of GSK-3β by phosphorylating GSK-3β in neurons compared to Ex-Con treatment (P<0.05, respectively).

Conclusions: Our data suggest that treatment of stroke with tailored exosomes enriched with the miR-17-92 cluster increases neural plasticity and functional recovery after stroke, possibly via targeting PTEN to activate the PI3K/Akt/mTOR/GSK-3β signaling pathway.

Intravenous Formulation of HET0016 Decreased Human Glioblastoma Growth and Implicated Survival Benefit in Rat Xenograft Models

Glioblastoma (GBM) is a hypervascular primary brain tumor with poor prognosis. HET0016 is a selective CYP450 inhibitor, which has been shown to inhibit angiogenesis and tumor growth. Therefore, to explore novel treatments, we have generated an improved intravenous (IV) formulation of HET0016 with HPßCD and tested in animal models of human and syngeneic GBM. Administration of a single IV dose resulted in 7-fold higher levels of HET0016 in plasma and 3.6-fold higher levels in tumor at 60 min than that in IP route. IV treatment with HPßCD-HET0016 decreased tumor growth, and altered vascular kinetics in early and late treatment groups (p < 0.05). Similar growth inhibition was observed in syngeneic GL261 GBM (p < 0.05). Survival studies using patient derived xenografts of GBM811, showed prolonged survival to 26 weeks in animals treated with focal radiation, in combination with HET0016 and TMZ (p < 0.05). We observed reduced expression of markers of cell proliferation (Ki-67), decreased neovascularization (laminin and αSMA), in addition to inflammation and angiogenesis markers in the treatment group (p < 0.05). Our results indicate that HPßCD-HET0016 is effective in inhibiting tumor growth through decreasing proliferation, and neovascularization. Furthermore, HPßCD-HET0016 significantly prolonged survival in PDX GBM811 model.

Targeting Triple Negative Breast Cancer with a Small-sized Paramagnetic Nanoparticle

There is no available targeted therapy or imaging agent for triple negative breast cancer (TNBC). We developed a small-sized dendrimer-based nanoparticle containing a clinical relevant MRI contrast agent, GdDOTA and a NIR fluorescent dye, DL680. Systemic delivery of dual-modal nanoparticles led to accumulation of the agents in a flank mouse model of TNBC that were detected by both optical and MR imaging. In-vivo fluorescence images, as well as ex-vivo fluorescence images of individual organs, demonstrated that nanoparticles accumulated into tumor selectively. A dual modal strategy resulted in a selective delivery of a small-sized (GdDOTA)42-G4-DL680 dendrimeric agent to TNBC tumors, avoiding other major organs.

Myelin-targeted, texaphyrin-based multimodal imaging agent for magnetic resonance and optical imaging

Reliable methods of imaging myelin are essential to investigate the causes of demyelination and to study drugs that promote remyelination. Myelin-specific compounds can be developed into imaging probes to detect myelin with various imaging techniques. The development of multimodal myelin-specific imaging probes enables the use of orthogonal imaging techniques to accurately visualize myelin content and validate experimental results. Here, we describe the synthesis and application of multimodal myelin-specific imaging agents for light microscopy and magnetic resonance imaging. The imaging agents were synthesized by incorporating the structural features of luxol fast blue MBS, a myelin-specific histological stain, into texaphyrins coordinated to Gd^III . These new complexes demonstrated absorption of visible light, emission of near-IR light, and relaxivity values greater than clinically approved contrast agents for magnetic resonance imaging. These properties enable the use of optical imaging and magnetic resonance imaging for visualization of myelin. We performed section- and en block-staining of ex vivo mouse brains to investigate the specificity for myelin of the new compounds. Images obtained from light microscopy and magnetic resonance imaging demonstrate that our complexes are retained in white matter structures and enable detection of myelin. Copyright © 2016 John Wiley & Sons, Ltd.

Targeting Glioma with a Dual Mode Optical and Paramagnetic Nanoprobe across the Blood-brain Tumor Barrier

In brain tumors, delivering nanoparticles across the blood-tumor barrier presents major hurdles. A clinically relevant MRI contrast agent, GdDOTA and a near-infrared (NIR) fluorescent dye, DL680 were conjugated to a G5 PAMAM dendrimer, thus producing a dual-mode MRI and NIR imaging agent. Systemic delivery of the subsequent nano-sized agent demonstrated glioma-specific accumulation, probably due to the enhanced permeability and retention effect. In vivo MRI detected the agent in glioma tissue, but not in normal contralateral tissue; this observation was validated with in vivo and ex vivo fluorescence imaging. A biodistribution study showed the agent to have accumulated in the glioma tumor and the liver, the latter being the excretion path for a G5 dendrimer-based agent.

pH-Dependent Cellular Internalization of Paramagnetic Nanoparticle

A hallmark of the tumor microenvironment in malignant tumor is extracellular acidosis, which can be exploited for targeted delivery of drugs and imaging agents. A pH sensitive paramagnetic nanoaparticle (NP) is developed by incorporating GdDOTA-4AmP MRI contrast agent and pHLIP (pH Low Insertion Peptide) into the surface of a G5-PAMAM dendrimer. pHLIP showed pH-selective insertion and folding into cell membranes, but only in acidic conditions. We demonstrated that pHLIP-conjugated Gd₄₄-G5 paramagnetic nanoparticle binds and fuses with cellular membrane at low pH, but not at normal physiological pH, and that it promotes cellular uptake. Intracellular trafficking of NPs showed endosomal/lysosomal path ways.

Targeted Theranostic Approach for Glioma Using Dendrimer-Based Curcumin Nanoparticle

The delivery of anti-cancer agents to brain tumors represent a challenge because the blood-brain tumor barrier (BBTB) effectively limits the delivery of many agents. A new generation 3 (G3) dendrimer-based curcumin (Curc) conjugate was synthesized. The synthesized G3-Curc conjugate demonstrated full solubility in aqueous media. The in vitro study revealed that G3-Curc nanoparticles were internalized into glioma U-251 cells. Systemic delivery of G3-Curc conjugate led to preferentially accumulation in an orthotopic preclinical glioma model minimizing systemic toxic effect. Multicolor microscopy images of the tumor tissue showed that G3-Curc particles were internalized inside tumor cells selectively and further localized within nuclei. Enhanced bioavailability of G3-Curc conjugate was also observed with improved therapeutic efficacy against different cancers cells.

Effect of Curcumin on Pro-angiogenic Factors in the Xenograft Model of Breast Cancer

The formation of a new blood vessel is stimulated by angiogenic factors. Curcumin, which is the active ingredient of the spice plant Curcuma longa L and is used as food and traditional medicine, has shown anticancer effects against different types of cancers. We evaluated the effects of curcumin on angiogenesis/pro-angiogenic factors in a mouse model of human breast cancer. Cell viability was measured by the MTT assay after curcumin treatment in triple-negative breast cancer cells (MDA-MB-231). For the in vivo study, human breast cancer was induced in athymic mice and treated with 300 mg/kg/day of curcumin administered intraperitoneally. Tumor size was measured weekly, and the animals underwent single photon emission computed tomography (SPECT) scanning with Tc-99m tagged VEGF-c to detect the in vivo expression of VEGFR2/3. In addition, the expression of proangiogenic/ growth factors in the tumor extracts was evaluated by a membrane antibody array. Histological analysis was performed to confirm the effect of curcumin on neovascularization. The MTT assay showed that curcumin significantly reduced the cell viability of MDA-MB-231 cells. In breast cancer xenografts, curcumin treatment led to a decrease in tumor volume and cell proliferation (Ki-67) compared with the vehicle treated group. Tc-99m-HYNIC-VEGF-c-SPECT imaging showed decreased uptake to the tumor, which may indicate a lower expression of VEGFR2/3 in curcumin treated tumors; however, a statistically significant difference was not achieved (p>0.05). Additionally, curcumin treatment showed a significantly low level of expression of pro-angiogenic factors (p<0.05) and a decrease in micro-vessel density (vWF) in animals compared with that of vehicle treated tumors. In conclusion, curcumin treatment showed effectiveness in reducing tumor growth and cell proliferation, as well as in the inhibition of angiogenesis.

Are hypertensive disorders in pregnancy associated with congenital malformations in offspring? Evidence from the WHO Multicountry cross sectional survey on maternal and newborn health

BACKGROUND

Annually, around 7.9 million children are born with birth defects and the contribution of congenital malformations to neonatal mortality is generally high. Congenital malformations in children born to mothers with hypertensive disorders during pregnancy has marginally been explored.

METHODS

Country incidence of congenital malformations was estimated using data on the 310 401 livebirths of the WHO Multicountry Survey which reported information from 359 facilities across 29 countries. A random-effect logistic regression model was utilized to explore the associations between six broad categories of congenital malformations and the four maternal hypertensive disorders "Chronic Hypertension", "Preeclampsia" and "Eclampsia" and "Chronic hypertension with superimposed preeclampsia".

RESULTS

The occupied territories of Palestine presented the highest rates in all groups of malformation except for the "Lip/Cleft/Palate" category. Newborns of women with chronic maternal hypertension were associated with a 3.7 (95 % CI 1.3-10.7), 3.9 (95 % CI 1.7-9.0) and 4.2 (95 % CI 1.5-11.6) times increase in odds of renal, limb and lip/cleft/palate malformations respectively. Chronic hypertension with superimposed preeclampsia was associated with a 4.3 (95 % CI 1.3-14.4), 8.7 (95 % CI 2.5-30.2), 7.1 (95 % CI 2.1-23.5) and 8.2 (95 % CI 2.0-34.3) times increase in odds of neural tube/central nervous system, renal, limb and Lip/Cleft/Palate malformations.

CONCLUSIONS

This study shows that chronic hypertension in the maternal period exposes newborns to a significant risk of developing renal, limb and lip/cleft/palate congenital malformations, and the risk is further exacerbate by superimposing eclampsia. Additional research is needed to identify shared pathways of maternal hypertensive disorders and congenital malformations.

Abstract 466: MR prediction of tumor burden in Patient-Derived Mouse Xenografts model of glioblastoma using an adaptive model

Introduction: In human glioblastoma multiforme (GBM), infiltrating cells are found in remote locations, even in the hemisphere contralateral to the primary lesion. Magnetic Resonance Imaging (MRI) allows approximation of the extent of tumor cell infiltration. However, the actual extent of infiltration may be greater or less than the edema, and there is no standard MRI practice that allow exploring the infiltrating tumor burden. This pilot study investigates the feasibility of using a set of MR modalities for the development of an MRI estimate of infiltrating tumor burden in Patient-Derived Mouse Xenografts model of GBM using an adaptive model.

Material and Methods: 8 mice implanted with GBM CSC HF2927 were studied. MRI studies were performed in a Direct Drive Varian 7 Tesla. The following image sets were acquired: high-res. T1-weighted; T2-weighted (TE/TR = (20, 40, 60, 80)/3000 ms); MT-weighted fast spin-echo. Magnevist (0.25 mmol/kg i.p) was injected about 5 minutes before the post-contrast T1-weighted image set was acquired. The animal was sacrificed immediately after MRI and stained for the presence of human GBM cells. We used the following MRI sequences to establish a basis set for training the AM: pre- and post-contrast (Magnevist, I.P.) T1-weighted, 4-echo T2, MT, 3-direction, 3 b-value diffusion-weighted. Maps of T2 and proton density (T2-PD) were produced by fitting the T2 data. The histology image was warped and co-registered to the T2-PD image using mouse brain anatomical landmarks. MR image sets were normalized to the white matter area of the brain, and each voxel profile extracted from the 9 image set was normalized to the summation of two normalized T2 images (echo 2 and 3), following which the normalized profile along with the co-registered histology was used for training and testing of an artificial neural network (ANN) with Multi-Layer perceptron architecture to predict the presence of local tumor burden in form of tumorous cell density.

Results and Conclusions: The ANN was successfully trained and validated using K-Fold Cross Validation technique (KFCV) and the 9 MR modalities as its input set. Results imply that the chosen MRI feature set contains adequate information content for training the ANN. The predictive power of the ANN was ∼ 0.81. The correlation coefficient for the association between the predicted map and histology was ∼ 0.85. Given the success of training an ANN to predict infiltrating tumor burden, it may be possible to identify similar or different basis set of MRI images that can robustly predict both infiltrating and solid tumor burden in human GBM.

Citation Format: Hassan Bagher-Ebadian, Ana deCarvalho, Azimeh NV Dehkordi, Tavarekere Nagaraja, Susan Irtenkauf, Swayamparva Panda, Meser M. Ali, Arbab S. Ali, Hamid Soltanian-Zadeh, Robert Knight, James R. Ewing. MR prediction of tumor burden in Patient-Derived Mouse Xenografts model of glioblastoma using an adaptive model. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 466.

Abstract 2710: Model evolution technique as a novel concept for characterization of tumor heterogeneity in dynamic contrast enhanced MRI studies

Introduction: Many studies have shown that tumor vascular network and the assortment of tumorous cells inside and on the periphery of solid tumors are spatially heterogeneous. Variation in cell packing density (VCPD), hypoxia, acidosis, and elevated interstitial fluid pressure (IFP) are main characteristic features of solid tumors. Elevated IFP and VCPD in solid tumors can be generally relevant to the pathological structures at the cellular level that is fundamental to understanding the chance of response to treatment and recurrence. Therefore, non-invasive quantification of tumor heterogeneity for the same types of tumors can play an important role in diagnosis and treatment planning.

Hypothesis: In this pilot study, using Nested Model (NM) selection technique, Model Evolution (ME) concept is framed and introduced to quantify the evolutions of 3 different physiologically NM that are derived from standard Tofts model, throughout the course of Dynamic Contrast Enhanced (DCE) Magnetic Resonance Imaging (MRI) experiment. Using ME technique for pharmacokinetic (PK) modeling and DCE-MRI data analysis, a heterogeneity measure is formulated and introduced based on the evolutionary profile of the estimated extra-cellular extra-vascular (ve) volume. We hypothesized that the ME profiles in the course of DCE-MRI experiment, highly depend on the inward diffusion and outward convection of contrast agent concentration and contain abundant information for describing the compartmentalization and heterogeneity levels of solid tumors.

Material and Methods: 24 athymic Nude rats with U251n rat tumor model of cerebral tumor were studied. Look-Locker T1 mapping and DCE-MRI experiments (Dual Gradient Echo, 150 image sets at 4.0 sec intervals over 10 min: matrix = 128×64, five 2.0 mm slices, NE = 2, NA = 1, TE/TE/TR = 2.0/4.0/40ms with bolus intravenous injection of the Magnevist at 0.25 mmol/kg) acquired at 7T field strengths. In each animal, in-vivo measurement of tumor IFP was done right after the DCE-MRI experiment using a wick-in-needle technique. The ME technique was applied on DCE-MR data of 24 U251n rat tumors to characterize the heterogeneity of each tumor and then the results were compared to their known in vivo measure of IFPs.

Results and Conclusions: Results of this pilot study clearly attest that the evolutionary profile of ve can be used to characterize the heterogeneity level of solid tumors. The ME results imply that as the slop of the evolutionary profile increases, the IFP of tumor increases. Also, the latency of the profile during the course of MR experiment can reliably explain the tumor compartmentalization and their elevated IFP. This pilot study confirms that the ME concept can make a paradigm shift in non-invasive quantification of tumor heterogeneity from DCE-MRI studies

Citation Format: Hassan Bagher-Ebadian, Azimeh NV Dehkordi, Rasha Alamgharibi, David Nathanson, Hamid Soltanian-Zadeh, Arbab S. Ali, Stephen Brown, Meser M. Ali, Tom Mikkelsen, James R. Ewing. Model evolution technique as a novel concept for characterization of tumor heterogeneity in dynamic contrast enhanced MRI studies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2710.

Abstract 1316: Targeted therapeutic approach for triple negative breast cancer using paramagnetic nanoparticle

Breast cancer (BC) is a spectrum of diseases with distinct molecular alterations accounting for differences in treatment response and outcome. Gene expression profiling defines much of this molecular heterogeneity and has been used to stratify the disease into different molecular subtypes. Triple-negative breast cancer (TNBC) refers to a subtype of breast cancer that is negative for estrogen receptors (ER) and/or progesterone receptors (PR), and lacks HER2 overexpression. Therefore, this subtype of breast cancer lacks the benefits of specific therapies which target these receptors. TNBC has been characterized by an acidic extracellular environment. In human aggressive breast tumors, extracellular pH (pHe) has been measured by microelectrode and the values are in good agreement with the values observed in animal systems i.e. that the pHe is significantly acidic in the range from 6.2 to 7.0. However, tumor intracellular pH is either neutral or alkaline. Interestingly, a similar pH gradient is not observed in normal tissues. Therefore, this acidic extracellular pH (pHe) within tumor tissues can be exploited for targeted delivery of drugs and imaging agents.

Recently, A pH low insertion peptide (pHLIP) derived from the protein bacteriorhodopsin has been found to target tumor acidic pHe. The peptide inserts across cell membranes as an alpha-helix when extracellular pH (pHe) is acidic, but does not form the helix at normal or alkaline pH. Since aggressive TNBC has an acidic environment, the pHLIP will insert into the cancer cell membrane, but the pHLIP will not insert into the cell membranes of normal tissues, providing excellent specificity for targeting TNBC. Our initial study demonstrated the detection of breast tumor in rodent by dendrimer-based paramagnetic nanoparticles nonspecifically. To develop this nanoparticle as a platform, it should easily accommodate targeting ligands for selective localization at the acidic tumor microenvironment and for therapeutic drugs that can be released selectively into TNBC tumor cells. Here, we demonstrate that pHLIP-tagged nanoparticles bind to and are internalized by TNBC cells in in-vitro. Systemic delivery of paramagnetic nanoparticle, Gd-G5-pHLIP (NP-pHLIP) leads to accumulation of the NPs in a flank mouse model of TNBC tumor that are detected by both optical and MR imaging.

Finally, we have conjugated doxorubicin (dox) with pHLIP3-NP via hydrazone bond formation. We have successfully incorporated 20 dox molecules with pHLIP3-NP via a pH-sensitive hydrazone bond as evidenced by maldi-tof analyses. A cohort of 6 mice was treated with pHLIP-NP-dox and a second cohort of 6 mice was treated with vehicle. A solution of 0.04 mmol/kg pHLIP-NP-dox (12mg/kg equivalent dose of dox) was injected through the tail vein catheter at day 8 and 14. We generated T2 maps on day 21′to calculate tumor volume by following our previous reports. We observed a short-term tumor regression by pHLIP-NP-dox infusion.

Citation Format: Meser M. Ali, Li Zhang, Hassan Bagher Ebadian, James R. Ewing. Targeted therapeutic approach for triple negative breast cancer using paramagnetic nanoparticle. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1316.

Spectroscopic Characterization of the 3+ and 2+ Oxidation States of Europium in a Macrocyclic Tetraglycinate Complex

The 3+ and 2+ oxidation states of europium have drastically different magnetic and spectroscopic properties. Electrochemical measurements are often used to probe Eu^III/II oxidation state changes, but a full suite of spectroscopic characterization is necessary to demonstrate conversion between these two oxidation states in solution. Here, we report the facile conversion of an europium(III) tetraglycinate complex into its Eu^II analogue. We present electrochemical, luminescence, electron paramagnetic resonance, UV-visible, and NMR spectroscopic data demonstrating complete reversibility from the reduction and oxidation of the 3+ and 2+ oxidation states, respectively. The Eu^II-containing analogue has kinetic stability within the range of clinically approved Gd^III-containing complexes using an acid-catalyzed dissociation experiment. Additionally, we demonstrate that the 3+ and 2+ oxidation states provide redox-responsive behavior through chemical-exchange saturation transfer or proton relaxation, respectively. These results will be applicable to a wide range of redox-responsive contrast agents and Eu-containing complexes.

Introduction and enzootic of A/H5N1 in Egypt: Virus evolution, pathogenicity and vaccine efficacy ten years on

It is almost a decade since the highly pathogenic H5N1 avian influenza virus (A/H5N1) of clade 2.2.1 was introduced to Egypt in 2005, most likely, via wild birds; marking the longest endemic status of influenza viruses in poultry outside Asia. The endemic A/H5N1 in Egypt still compromises the poultry industry, poses serious hazards to public health and threatens to become potentially pandemic. The control strategies adopted for A/H5N1 in Egyptian poultry using diverse vaccines in commercialized poultry neither eliminated the virus nor did they decrease its evolutionary rate. Several virus clades have evolved, a few of them disappeared and others prevailed. Disparate evolutionary traits in both birds and humans were manifested by accumulation of clade-specific mutations across viral genomes driven by a variety of selection pressures. Viruses in vaccinated poultry populations displayed higher mutation rates at the immunogenic epitopes, promoting viral escape and reducing vaccine efficiency. On the other hand, viruses isolated from humans displayed changes in the receptor binding domain, which increased the viral affinity to bind to human-type glycan receptors. Moreover, viral pathogenicity exhibited several patterns in different hosts. This review aims to provide an overview of the viral evolution, pathogenicity and vaccine efficacy of A/H5N1 in Egypt during the last ten years.

Dendrimer-Based Responsive MRI Contrast Agents (G1-G4) for Biosensor Imaging of Redundant Deviation in Shifts (BIRDS)

Biosensor imaging of redundant deviation in shifts (BIRDS) is a molecular imaging platform for magnetic resonance that utilizes unique properties of low molecular weight paramagnetic monomers by detecting hyperfine-shifted nonexchangeable protons and transforming the chemical shift information to reflect its microenvironment (e.g., via temperature, pH, etc.). To optimize translational biosensing potential of BIRDS we examined if this detection scheme observed with monomers can be extended onto dendrimers, which are versatile and biocompatible macromolecules with modifiable surface for molecular imaging and drug delivery. Here we report on feasibility of paramagnetic dendrimers for BIRDS. The results show that BIRDS is resilient with paramagnetic dendrimers up to the fourth generation (i.e., G1-G4), where the model dendrimer and chelate were based on poly(amido amine) (PAMAM) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA(4-)) complexed with thulium ion (Tm(3+)). Temperature sensitivities of two prominent signals of Gn-PAMAM-(TmDOTA(-))x (where n = 1-4, x = 6-39) were comparable to that of prominent signals in TmDOTA(-). Transverse relaxation times of the coalesced nonexchangeable protons on Gn-PAMAM-(TmDOTA(-))x were relatively short to provide signal-to-noise ratio that was comparable to or better than that of TmDOTA(-). A fluorescent dye, rhodamine, was conjugated to a G2-PAMAM-(TmDOTA)12 to create a dual-modality nanosized contrast agent. BIRDS properties of the dendrimer were unaltered with rhodamine conjugation. Purposely designed paramagnetic dendrimers for BIRDS in conjunction with novel macromolecular surface modification for functional ligands/drugs could potentially be used for biologically compatible theranostic sensors.

Concentration-independent MRI of pH with a dendrimer-based pH-responsive nanoprobe

The measurement of extracellular pH (pHe ) has significant clinical value for pathological diagnoses and for monitoring the effects of pH-altering therapies. One of the major problems of measuring pHe with a relaxation-based MRI contrast agent is that the longitudinal relaxivity depends on both pH and the concentration of the agent, requiring the use of a second pH-unresponsive agent to measure the concentration. Here we tested the feasibility of measuring pH with a relaxation-based dendritic MRI contrast agent in a concentration-independent manner at clinically relevant field strengths. The transverse and longitudinal relaxation times in solutions of the contrast agent (GdDOTA-4AmP)44 -G5, a G5-PAMAM dendrimer-based MRI contrast agent in water, were measured at 3 T and 7 T magnetic field strengths as a function of pH. At 3 T, longitudinal relaxivity (r1 ) increased from 7.91 to 9.65 mM(-1) s(-1) (on a per Gd(3+) basis) on changing pH from 8.84 to 6.35. At 7 T, r1 relaxivity showed pH response, albeit at lower mean values; transverse relaxivity (r2 ) remained independent of pH and magnetic field strengths. The longitudinal relaxivity of (GdDOTA-4AmP)44 -G5 exhibited a strong and reversible pH dependence. The ratio of relaxation rates R2 /R1 also showed a linear relationship in a pH-responsive manner, and this pH response was independent of the absolute concentration of (GdDOTA-4AmP)44 -G5 agent. Importantly, the nanoprobe (GdDOTA-4AmP)44 -G5 shows pH response in the range commonly found in the microenvironment of solid tumors.

Abstract P1-01-13: Triple negative breast cancer targeting paramagnetic nanoparticle for non-invasive tumor imaging

Triple-negative breast cancer (TNBC) refers to a subtype of breast cancer that is negative for estrogen receptors (ER) and/or progesterone receptors (PR) , and lacks HER2 overexpression. Therefore, this subtype of breast cancer lacks the benefits of specific therapies which target these receptors. TNBC has been characterized by an acidic extracellular environment. In human aggressive breast tumors, pHe has been measured by microelectrode and the values are in good agreement with the values observed in animal systems i.e. that the pHe is significantly acidic in the range from 6.2 to 7.0. However, tumor intracellular pH is either neutral or alkaline. Interestingly, a similar pH gradient is not observed in normal tissues. Therefore, this acidic extracellular pH (pHe) within tumor tissues can be exploited for targeted delivery of drugs and imaging agents. Recently, A pH low insertion peptide (pHLIP) derived from the protein bacteriorhodopsin has been found to target tumor acidic pH. The peptide inserts across cell membranes as an α-helix when extracellular pH (pHe) is acidic, but does not form the helix at normal or alkaline pH. Since aggressive TNBC has an acidic environment, the pHLIP will insert into the cancer cell membrane, but the pHLIP will not insert into the cell membranes of normal tissues, providing excellent specificity for targeting TNBC. Here, we demonstrate that pHLIP-tagged nanoparticles bind to and are internalized by TNBC cells in vitro. Systemic delivery of the Gd-G5-pHLIP leads to accumulation of the nanoparticles in a flank mouse model of TNBC tumor that are detected by optical and MR imaging.

We have synthesized pH-responsive MRI nanoprobe, phosphonate G5-(GdDOTA-4AmP) by following our published synthetic method. The MW of the conjugated G5 dendrimer was estimated at 79,082 g/mole by maldi-tof analysis. This corresponds to a G5-dendrime with an average of 44 chelated Gd3+ ions per dendrimer. Gd44-G5 dendrimer was reacted with heterobifunctional cross-linker (sulfo-SMCC) to form reactive maleimides and then maleimide- Gd44-G5 dendrimer was coupled with C-terminus cysteine group of biotinylated Bt-pHLIP (AEQNPIYWARYADWLFTTPLLLLDLALLVDADEGTCG-pegBiotin). The HABA assay with biotin and avidin revealed that on average 3.1 molecules of biotin are present in Gd44-G5-Bt-pHLIP dendrimer. Finally, Rhodamine dye was conjugated to amines surface of preloaded Gd44-G5-Bt-pHLIP3 in order to achieve final conjugate Rhodamine-Gd44-G5-Bt-pHLIP3.

To study pH-dependent translocation of molecules across the cell membrane, we have added Rho-Gd-G5-Bt-pHLIP to the cells and incubated for 3 h at pH 7.4 and 6.5. The cellular uptake of Rho-Gd-G5-pHLIP was significantly higher at pH 6.5. When Rho-Gd-G5 was used, the cellular uptake was considerable lower at both, pH 6.5 and 7.4. Hence, we have shown the ability of pHLIP peptide for intracellular delivery of Gd-G5 nanoparticles in vitro at pH 6.5 but the same ability is attenuated significantly at neutral pH. We have created a mouse model of TNBC MDA-MB-231 tumor. The pharmacokinetics of Gd44-G5-pHLIP was visualized in the MDA-MB-231 tumor over the course of 105 min post-contrast administration.

Citation Format: Meser M Ali, Nadimpalli RS Varma, Branislava Janic, Li Zhang, James R Ewing. Triple negative breast cancer targeting paramagnetic nanoparticle for non-invasive tumor imaging [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-01-13.

SLE presenting as multiple hemorrhagic complications

A 24 year old female with hereditary spastic paraplegia presented with intermittent headache for one year. She also had lower abdominal pain and vomiting for two months. She was pale, had icterus and mild splenomegaly. On diagnostic evaluation she was found to have hemolytic anemia, thrombocytopenia and bilateral adrenal, subdural, soft tissue (scalp and orbit) hemorrhages due to systemic lupus erythematosus (SLE). However, antiphospholipid syndrome (APS) antibodies were negative. Bilateral adrenal hemorrhage without associated APS is a rare phenomenon in SLE. We describe a case of SLE presenting with sequence of rare hemorrhagic complications in concert.

Oxidation-responsive Eu(2+/3+)-liposomal contrast agent for dual-mode magnetic resonance imaging

An oxidation-responsive contrast agent for magnetic resonance imaging was synthesized using Eu(2+) and liposomes. Positive contrast enhancement was observed with Eu(2+), and chemical exchange saturation transfer was observed before and after oxidation of Eu(2+). Orthogonal detection modes render the concentration of Eu inconsequential to molecular information provided through imaging.