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Supplementary Table 1 from E-3810 Is a Potent Dual Inhibitor of VEGFR and FGFR that Exerts Antitumor Activity in Multiple Preclinical Models

Supplementary Figures 1-4 from E-3810 Is a Potent Dual Inhibitor of VEGFR and FGFR that Exerts Antitumor Activity in Multiple Preclinical Models

Supplementary Table 2 from E-3810 Is a Potent Dual Inhibitor of VEGFR and FGFR that Exerts Antitumor Activity in Multiple Preclinical Models

Supplementary Methods, Figure Legends 1-4 from E-3810 Is a Potent Dual Inhibitor of VEGFR and FGFR that Exerts Antitumor Activity in Multiple Preclinical Models

Objective: Contrast-enhanced MRI could be useful to guide high-intensity focused ultrasound treatment (HIFU), but the effects of HIFU on gadolinium-based agents is not known. Here, we tested in vitro the stability of gadoteridol and gadobenate dimeglumine, two widely used MR contrast agents, after exposure to HIFU at power levels typically applied in the clinical practice. Methods: 0.5 M (gadoteridol and gadobenate dimeglumine) and diluted formulations (1:10 gadoteridol in saline) were exposed to different HIFU sequences. Unexposed and exposed solutions were characterized by high-performance liquid chromatography in terms of concentration of gadolinium complex, free gadolinium and free ligand. Results: Gadoteridol formulation after treatment showed concentrations of the complex not significantly different from control. Free Gd and/or free ligand concentrations in the order of 0.002/0.004% w/w, were observed occasionally without significant correlation with intensity and duration of exposure to HIFU. Gadobenate dimeglumine formulation after treatment showed complex assay content values, by-products (0.24–0.26%) and free BOPTA levels (0.07%) comparable to control sample within the experimental error. Conclusion: In the range of conditions explored, HIFU exposure did not induce significant dissociations of gadoteridol and gadobenate dimeglumine, nor a detectable increase in the concentration of free species. Advances in knowledge: Our study strengthens the hypothesis that gadolinium-based contrast agents are stable during HIFU treatment for body applications (e.g. thermal ablation of uterine fibroids).

BACKGROUND Studies of gadolinium (Gd) clearance from animals in the first weeks after administration of gadolinium-based contrast agents (GBCAs) have previously looked at solitary timepoints only. However, this does not give information on differences between GBCAs and between organs in terms of Gd elimination kinetics. PURPOSE To compare Gd levels in rat cerebellum, cerebrum, skin, and blood at 1, 2, 3, and 5 weeks after repeated administration of macrocyclic GBCAs. STUDY TYPE Prospective. ANIMAL MODEL One hundred eighty male Sprague-Dawley rats randomized to three groups (n = 60/group), received intravenous administrations of gadoteridol, gadoterate meglumine, or gadobutrol (0.6 mmol/kg for each) four times/week for 5 consecutive weeks. Rats were sacrificed after washout periods of 1, 2, 3, or 5 weeks. FIELD STRENGTH/SEQUENCE Not applicable. ASSESSMENT Cerebellum, cerebrum, skin, and blood were harvested for Gd determination by inductively coupled plasma-mass spectrometry (15 animals/group/all timepoints). STATISTICAL TESTS Anova and Dunnett's test (data with homogeneous variances and normal distribution). Kruskal-Wallis and Wilcoxon's rank sum tests (data showing nonhomogeneous variances or a non-normal distribution, significance levels: P

Gadolinium(III) complexes have been employed for more than 30 years as contrast agents in magnetic resonance imaging (MRI). In order to further improve the diagnostic accuracy of enhanced magnetic resonance images or to provide comparable enhancement at a reduced administered dose, current research is focusing on the development of GdIII-complexes characterized by higher relaxivity. In this study we describe the synthesis and the equilibrium, kinetic, relaxation and structural properties of two new GdIII-complexes based on modified 10-(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (HP-DO3A) structure which, due to an intramolecular prototropic exchange, display more than two-fold higher relaxivity compared to currently available GdIII-based MRI contrast agents.

The interactions of gadoterate meglumine, gadobutrol, gadoteridol and Gd(HB-DO3A) with bovine Type I collagen were investigated by ultrafiltration and dialysis. The affinity of the four agents to collagen is similar. However, the maximum adsorbed amount of GdIII-complexes decreases in the following order: gadoterate meglumine > gadobutrol > gadoteridol > Gd(HB-DO3A). Calculations with the open three-compartment model reveal that the structural homologs gadoteridol and Gd(HB-DO3A) have a lower adsorption onto collagen, which may explain the less prolonged in vivo retention of gadoteridol observed in soft tissues of rats.

Breast cancer is the most common cancer among women worldwide. For high-risk women, contrast enhanced (CE)-magnetic resonance imaging (MRI) is recommended as supplemental screening together with mammography. The development of new MRI contrast agents is an active field of research, which requires efficacy tests on appropriate preclinical pathological models. In this work, a refined method to orthotopically induce breast cancer in BALB/c mice was developed using ultrasound (US) as a guide for the precise localisation of the tumour induction site and to improve animal welfare. The method was coupled with CE-MRI to characterise the evolution of the tumoural lesion.

Glucose is the central nervous system’s only energy source. Imaging techniques capable to detect pathological alterations of the brain metabolism are useful in different diagnostic processes. Such techniques are also beneficial for assessing the evaluation efficacy of therapies in pre-clinical and clinical stages of diseases. Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) is a possible alternative to positron emission tomography (PET) imaging that has been widely explored in cancer research in humans and animal models. We propose that pathological alterations in brain 2-deoxy-D-glucose (2DG) uptake, typical of neurodegenerative diseases, can be detected with CEST MRI. Transgenic mice overexpressing a mutated form of amyloid precusrsor protein (APP23), a model of Alzheimer’s disease, analyzed with CEST MRI showed a clear reduction of 2DG uptake in different brain regions. This was reminiscent of the cerebral condition observed in Alzheimer’s patients. The results indicate the feasibility of CEST for analyzing the brain metabolic state, with better image resolution than PET in experimental models.

The relaxivity of Gd(HP-DO3A) was studied as a function of pH and buffer composition in order to identify the main factors of the observed relaxation enhancement due to the exchange of the coordinated hydroxyl proton. It was established that the paramagnetic relaxation time, T1M, of the coordinated hydroxyl proton is about 50% shorter than that of the protons in the coordinated water molecule. The control of the p K of the coordinated alcoholic -OH moiety in the ligand is fundamental to utilize the proton exchange enhanced relaxivity under physio/pathologic conditions. A new derivative of Gd(HP-DO3A) was synthesized by replacing the -CH3 group with a -CF3 moiety. In this complex, the -OH group becomes more acidic. Consequently, the maximum contribution of the proton exchange to the relaxivity is shifted to a lower pH region with the fluorinated ligand.

The Gd(iii)-complexes of three novel HP-DO3A-like ligands have been investigated to assess the relationship between relaxometry and intramolecular catalysis of the proton exchange. The structures of these ligands differ from the parent HP-DO3A because the methyl group of the hydroxy-propyl arm has been replaced by -Ph-OH, -Ph-NH2 and -Ph-COOH, respectively. The phenol, amine and carboxylate functionalities display an intramolecular H-bonding with the coordinated hydroxyl moiety that affects either the pK values of the involved functionalities and the rate of the proton exchange process.

Purpose To compare the levels of gadolinium in the blood, cerebrum, cerebellum, liver, femur, kidneys, and skin after multiple exposure of rats to the macrocyclic gadolinium-based contrast agents (GBCAs) gadoterate, gadobutrol, and gadoteridol. Materials and Methods Fifty male Wistar Han rats were randomized to three exposure groups (n = 15 per group) and one control group (n = 5). Animals in the exposure groups received a total of 20 GBCA administrations (four administrations per week for 5 consecutive weeks) at a dose of 0.6 mmol/kg bodyweight. After a 28-day recovery period animals were sacrificed and the blood and tissues harvested for determination of gadolinium (Gd) levels. Gd determination was performed by inductively coupled plasma mass spectrometry (ICP-MS). Results After 28 days' recovery no Gd was found in the blood, liver, or skin of any animal in any group. Significantly lower levels of Gd were noted with gadoteridol compared to gadoterate and gadobutrol in the cerebellum (0.150 ± 0.022 vs. 0.292 ± 0.057 and 0.287 ± 0.056 nmol/g, respectively; P < 0.001), cerebrum (0.116 ± 0.036 vs. 0.250 ± 0.032 and 0.263 ± 0.045 nmol/g, respectively; P < 0.001), and kidneys (25 ± 13 vs. 139 ± 88 [P < 0.01] and 204 ± 109 [P < 0.001], respectively). Higher levels of Gd were noted in the femur (7.48 ± 1.37 vs. 5.69 ± 1.75 and 8.60 ± 2.04 nmol/g, respectively) with significantly less Gd determined for gadoterate than for gadobutrol (P < 0.001) and gadoteridol (P < 0.05). Conclusion Differences exist between macrocyclic agents in terms of their propensity to accumulate in tissues. The observed differences in Gd concentration point to differences in GBCA washout rates in this setting and in this experimental model, with gadoteridol being the GBCA that is most efficiently removed from both cerebral and renal tissues. Level of Evidence: 2 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2017.

Purpose To dissect the contributions to the longitudinal relaxivity (r1) of two commercial contrast agents (CAs), Gd-DOTA and Gd-HP-DO3A, and to synthesize/characterize a novel macrocyclic agent (Gd-Phen-DO3A) having superior r1. Methods Longitudinal relaxation rates R1 of the CAs in saline with/without human serum albumin (HSA), ionized simulated body fluid (i-SBF), viscous simulated body fluid (v-SBF), and human plasma were measured. Results have been interpreted to evince the main determinants to the observed r1 values. Results In v-SBF or in the presence of HSA, r1 is enhanced for all complexes, reflecting the viscosity increase and a weak interaction with proteins. The CAs further differentiate in plasma, with a relaxivity increase (versus saline) of approximately 1, 1.5, and 2.5 mM−1s−1 for Gd-DOTA, Gd-HPDO3A, and Gd-Phen-DO3A, respectively. R1 versus pH curves in i-SBF indicates that prototropic exchange sizably contributes to the relaxivity of Gd-HP-DO3A and Gd-Phen-DO3A. Conclusion The major contributions to r1 in the physiological environment have been highlighted, namely, increased viscosity, complex-protein interaction, and prototropic exchange. The control of these terms allows the design of novel macrocyclic structures with enhanced r1 as a result of an improved interaction with plasma's macromolecules and the shift of the prototropic exchange to physiological pH. Magn Reson Med 78:1523–1532, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Meningioma in vivo research is hampered by the difficulty of establishing an easy and reproducible orthotopic model able to mimic the characteristics of a human meningioma. Moreover, leptomeningeal dissemination and high mortality are often associated with such orthotopical models, making them useless for clinical translation studies. An optimized method for inducing meningiomas in nude mice at two different sites is described in this paper and the high reproducibility and low mortality of the models are demonstrated. Skull base meningiomas were induced in the auditory meatus and convexity meningiomas were induced on the brain surface of 23 and 24 nude mice, respectively. Both models led to the development of a mass easily observable by imaging methods. Dynamic contrast enhanced MRI was used as a tool to monitor and characterize the pathology onset and progression. At the end of the study, histology was performed to confirm the neoplastic origin of the diseased mass.

A dinuclear gadolinium(III) chelate containing two moieties of diethylenetriaminepentaacetic acid (DTPA), covalently conjugated to an analogue of deoxycholic acid, was synthesized and thoroughly characterized. A full relaxometric analysis was carried out, consisting of 1) the acquisition of nuclear magnetic resonance dispersion (NMRD) profiles in various media; 2) the study of binding affinity to serum albumin; 3) the measurement of 17 O transverse relaxation rate versus temperature, and 4) a transmetallation assay. In vivo biodistribution MRI studies at 1 T and blood pharmacokinetics assays were carried out in comparison with Gd-DTPA (Magnevist) and gadocoletic acid trisodium salt (B22956/1), two well-known Gd complexes that share the same chelating cage and the same deoxycholic acid residue of the Gd complex investigated herein ((GdDTPA)2 -Chol). High affinity for plasma protein and, in particular, the availability of more than one binding site, allows the complex to reach a fairly high relaxivity value in plasma (∼20 mm-1 s-1 , 20 MHz, 310 K) as well as to show unexpectedly enhanced properties of blood pooling, with an elimination half-life in rats approximately seven times longer than that of B22956/1.

Several molecules have been exploited for developing MRI pH sensors based on the chemical exchange saturation transfer (CEST) technique. A ratiometric approach, based on the saturation of two exchanging pools at the same saturation power, or by varying the saturation power levels on the same pool, is usually needed to rule out the concentration term from the pH measurement. However, all these methods have been demonstrated by using a continuous wave saturation scheme that limits its translation to clinical scanners. This study shows a new ratiometric CEST-MRI pH-mapping approach based on a pulsed CEST saturation scheme for a radiographic contrast agent (iodixanol) possessing a single chemical exchange site. This approach is based on the ratio of the CEST contrast effects at two different flip angles combinations (180 degrees/360 degrees and 180 degrees/720 degrees), keeping constant the mean irradiation RF power (B-avg power). The proposed ratiometric approach index is concentration independent and it showed good pH sensitivity and accuracy in the physiological range between 6.0 and 7.4. (C) 2017 Elsevier Inc. All rights reserved.

Purpose To compare the levels of gadolinium in the blood, cerebrum, cerebellum, liver, femur, kidneys, and skin after multiple exposure of rats to the macrocyclic gadolinium‐based contrast agents (GBCAs) gadoterate, gadobutrol, and gadoteridol. Materials and Methods Fifty male Wistar Han rats were randomized to three exposure groups (n = 15 per group) and one control group (n = 5). Animals in the exposure groups received a total of 20 GBCA administrations (four administrations per week for 5 consecutive weeks) at a dose of 0.6 mmol/kg bodyweight. After a 28‐day recovery period animals were sacrificed and the blood and tissues harvested for determination of gadolinium (Gd) levels. Gd determination was performed by inductively coupled plasma mass spectrometry (ICP‐MS). Results After 28 days' recovery no Gd was found in the blood, liver, or skin of any animal in any group. Significantly lower levels of Gd were noted with gadoteridol compared to gadoterate and gadobutrol in the cerebellum (0.150 ± 0.022 vs. 0.292 ± 0.057 and 0.287 ± 0.056 nmol/g, respectively; P < 0.001), cerebrum (0.116 ± 0.036 vs. 0.250 ± 0.032 and 0.263 ± 0.045 nmol/g, respectively; P < 0.001), and kidneys (25 ± 13 vs. 139 ± 88 [P < 0.01] and 204 ± 109 [P < 0.001], respectively). Higher levels of Gd were noted in the femur (7.48 ± 1.37 vs. 5.69 ± 1.75 and 8.60 ± 2.04 nmol/g, respectively) with significantly less Gd determined for gadoterate than for gadobutrol (P < 0.001) and gadoteridol (P < 0.05). Conclusion Differences exist between macrocyclic agents in terms of their propensity to accumulate in tissues. The observed differences in Gd concentration point to differences in GBCA washout rates in this setting and in this experimental model, with gadoteridol being the GBCA that is most efficiently removed from both cerebral and renal tissues. Level of Evidence: 2 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018;47:746–752.

An increased prevalence of liver diseases such as hepatitis C and nonalcoholic fatty liver results in an augmented incidence of the most common form of liver cancer, hepatocellular carcinoma (HCC). HCC is most often found in the cirrhotic liver and it can therefore be challenging to rely on anatomical information alone when diagnosing HCC. Valuable information on specific cellular metabolism can be obtained with high sensitivity thanks to an emerging magnetic resonance (MR) technique that uses 13C labeled hyperpolarized molecules. Our interest was to explore potential new high contrast metabolic markers of HCC using hyperpolarized 13C-MR. This work led to the identification of a class of substrates, low molecular weight ethyl-esters, which showed high specificity for carboxyl esterases and proved in many cases to possess good properties for signal enhancement. In particular, hyperpolarized [1,3-13C2]ethyl acetoacetate (EAA) was shown to provide a metabolic fingerprint of HCC. Using this substrate a liver cancer implanted in rats was diagnosed as a consequence of an ∼4 times higher metabolic substrate-to-product ratio than in the surrounding healthy tissue, (p = 0.009). Unregulated cellular uptake as well as cosubstrate independent enzymatic conversion of EAA, made this substrate highly useful as a hyperpolarized 13C-MR marker. This could be appreciated by the signal-to-noise (SNR) obtained from EAA, which was comparable to the SNR reported in a literature liver cancer study with state-of-the-art hyperpolarized substrate, [1-13C]pyruvate. Also, the contrast-to-noise (CNR) in the EAA based metabolic ratio images was significantly improved compared with the CNR in equivalent images reported using [1-13C]pyruvate.

The available theoretical approaches aiming at describing Dynamic Nuclear spin Polarization (DNP) in solutions containing molecules of biomedical interest and paramagnetic centers are not able to model the behaviour observed upon varying the concentration of trityl radicals or the polarization enhancement caused by moderate addition of gadolinium complexes. In this manuscript, we first show experimentally that the nuclear steady state polarization reached in solutions of pyruvic acid with 15 mM trityl radicals is substantially independent from the average internuclear distance. This evidences a leading role of electron (over nuclear) spin relaxation processes in determining the ultimate performances of DNP. Accordingly, we have devised a variant of the Thermal Mixing model for inhomogenously broadened electron resonance lines which includes a relaxation term describing the exchange of magnetic anisotropy energy of the electron spin system with the lattice. Thanks to this additional term, the dependence of the nuclear polarization on the electron concentration can be properly accounted for. Moreover, the model predicts a strong increase of the final polarization on shortening the electron spin-lattice relaxation time, providing a possible explanation for the effect of gadolinium doping., Comment: 13 pages, 12 figures

To dissect the contributions to the longitudinal relaxivity (rLongitudinal relaxation rates RIn v-SBF or in the presence of HSA, rThe major contributions to r

The extraordinary enhancement of the nuclear magnetic resonance (NMR) signal that can be obtained by dynamic nuclear polarization (DNP) techniques is prompting new avenues of research based on the in vivo detection of metabolic abnormalities associated with the onset and progression of human diseases. 13C-labelled short-chain fatty acids appear to be interesting candidates for this novel class of metabolic-active contrast agents (MCAs), as they have been shown to report on metabolic differences between healthy and ischaemic tissues in mice. In spite of their promising biological efficacy, the formulations of short-chain fatty acids that fulfil the many technical constraints of the DNP procedure, as it is today, may limit their clinical potential. New solutions have been sought to circumvent technology-related challenges and facilitate clinical translation of these molecules. In particular, it has been shown that, by using symmetric anhydrides as chemical precursors for short-chain fatty acids, no glass-forming additives are needed in the DNP formulations. Furthermore, novel esterified trityl radicals and lipophilic gadolinium complexes allow easy removal of the polarization-promoting additives at the end of the DNP process. By applying the three concepts reported, we have succeeded in preparing aqueous formulations of short-chain fatty acids for pharmaceutical use that have favourable properties compared with those obtained from current procedures. The use of organic derivatives as chemical precursors of the MCA of interest appears to be a generally valid concept, not restricted to symmetric anhydrides of fatty acids, which can markedly improve the clinical potential of other 13C-labelled compounds. Copyright © 2012 John Wiley & Sons, Ltd.

Tumor angiogenesis is a degenerate process regulated by a complex network of proangiogenic factors. Existing antiangiogenic drugs used in clinic are characterized by selectivity for specific factors. Antiangiogenic properties might be improved in drugs that target multiple factors and thereby address the inherent mechanistic degeneracy in angiogenesis. Vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) family members and their cognate receptors are key players in promoting tumor angiogenesis. Here we report the pharmacologic profile of E-3810, a novel dual inhibitor of the VEGF and FGF receptors. E-3810 potently and selectively inhibited VEGF receptor (VEGFR)-1, -2, and -3 and FGF receptor (FGFR)-1 and -2 kinases in the nanomolar range. Ligand-dependent phosphorylation of VEGFR-2 and FGFR-1 was suppressed along with human vascular endothelial cell growth at nanomolar concentrations. In contrast, E-3810 lacked cytotoxic effects on cancer cell lines under millimolar concentrations. In a variety of tumor xenograft models, including early- or late-stage subcutaneous and orthotopic models, E-3810 exhibited striking antitumor properties at well-tolerated oral doses administered daily. We found that E-3810 remained active in tumors rendered nonresponsive to the general kinase inhibitor sunitinib resulting from a previous cycle of sunitinib treatment. In Matrigel plug assays performed in nude mice, E-3810 inhibited basic FGF–induced angiogenesis and reduced blood vessel density as assessed by histologic analysis. Dynamic contrast-enhanced magnetic resonance imaging analysis confirmed that E-3810 reduced the distribution of angiogenesis-sensitive contrast agents after only 5 days of treatment. Taken together, our findings identify E-3810 as a potent antiangiogenic small molecule with a favorable pharmacokinetic profile and broad spectrum antitumor activity, providing a strong rationale for its clinical evaluation. Cancer Res; 71(4); 1396–405. ©2011 AACR.

Gd(III)-complexes have been employed for more than twentyfive years as MRI contrast agents. In the last decade, considerations about potential toxicity of residual gadolinium in patients suffering from severe kidney diseases have moved researchers to evaluate alternative solutions, among them Mn(II)-complexes, to shorten T1 and achieve good image contrast. In this article we report on the synthesis of a new Mn(II)-chelate, endowed with a deoxycholic acid residue designed to interact reversibly with serum albumin and to boost the usually low relaxivity associated with Mn(II)-complexes. Its detailed relaxometric characterization and the analysis of albumin binding behaviour showed remarkable properties, suggesting its potential use as MRI blood pool agent.

An increased prevalence of liver diseases such as hepatitis C and nonalcoholic fatty liver results in an augmented incidence of the most common form of liver cancer, hepatocellular carcinoma (HCC). HCC is most often found in the cirrhotic liver and it can therefore be challenging to rely on anatomical information alone when diagnosing HCC. Valuable information on specific cellular metabolism can be obtained with high sensitivity thanks to an emerging magnetic resonance (MR) technique that uses 13C labeled hyperpolarized molecules. Our interest was to explore potential new high contrast metabolic markers of HCC using hyperpolarized 13C-MR. This work led to the identification of a class of substrates, low molecular weight ethyl-esters, which showed high specificity for carboxyl esterases and proved in many cases to possess good properties for signal enhancement. In particular, hyperpolarized [1,3-13C2 ]ethyl acetoacetate (EAA) was shown to provide a metabolic fingerprint of HCC. Using this substrate a liver cancer implanted in rats was diagnosed as a consequence of an ∼4 times higher metabolic substrate-to-product ratio than in the surrounding healthy tissue, (p=0.009). Unregulated cellular uptake as well as cosubstrate independent enzymatic conversion of EAA, made this substrate highly useful as a hyperpolarized 13C-MR marker. This could be appreciated by the signal-to-noise (SNR) obtained from EAA, which was comparable to the SNR reported in a literature liver cancer study with state-of-the-art hyperpolarized substrate, [1-13C]pyruvate. Also, the contrast-to-noise (CNR) in the EAA based metabolic ratio images was significantly improved compared with the CNR in equivalent images reported using [1-13C]pyruvate.

We have explored the manifold physical scenario emerging from a model of Dynamic Nuclear Polarization (DNP) via thermal mixing under the hypothesis of highly effective electron-electron interaction. When the electron and nuclear reservoirs are also assumed to be in strong thermal contact and the microwave irradiation saturates the target electron transition, the enhancement of the nuclear polarization is expected to be considerably high even if the irradiation frequency is set far away from the centre of the ESR line (as already observed by Borghini) and the typical polarization time is reduced on moving towards the boundaries of said line. More reasonable behaviours are obtained by reducing the level of microwave saturation or the contact between electrons and nuclei in presence of nuclear leakage. In both cases the function describing the dependency of the steady state nuclear polarization on the frequency of irradiation becomes sharper at the edges and the build up rate decreases on moving off-resonance. If qualitatively similar in terms of the effects produced on nuclear polarization, the degree of microwave saturation and of electron-nucleus contact has a totally different impact on electron polarization, which is of course strongly correlated to the effectiveness of saturation and almost insensitive, at the steady state, to the magnitude of the interactions between the two spin reservoirs. The likelihood of the different scenario is discussed in the light of the experimental data currently available in literature, to point out which aspects are suitably accounted and which are not by the declinations of thermal mixing DNP considered here., Comment: 15 pages, 7 figures

A novel mathematical treatment is proposed for computing the time evolution of dynamic nuclear polarization processes in the low temperature thermal mixing regime. Without assuming any a priori analytical form for the electron polarization, our approach provides a quantitative picture of the steady state that recovers the well known Borghini prediction based on thermodynamics arguments, as long as the electrons-nuclei transition rates are fast compared to the other relevant time scales. Substantially different final polarization levels are achieved instead when the latter assumption is relaxed in the presence of a nuclear leakage term, even though very weak, suggesting a possible explanation for the deviation between the measured steady state polarizations and the Borghini prediction. The proposed methodology also allows to calculate nuclear polarization and relaxation times, once specified the electrons/nuclei concentration ratio and the typical rates of the microscopic processes involving the two spin species. Numerical results are shown to account for the manifold dynamical behaviours of typical DNP samples., 11 pages, 11 figures

The extraordinary enhancement of the nuclear magnetic resonance (NMR) signal that can be obtained by dynamic nuclear polarization (DNP) techniques is prompting new avenues of research based on the in vivo detection of metabolic abnormalities associated with the onset and progression of human diseases. (13) C-labelled short-chain fatty acids appear to be interesting candidates for this novel class of metabolic-active contrast agents (MCAs), as they have been shown to report on metabolic differences between healthy and ischaemic tissues in mice. In spite of their promising biological efficacy, the formulations of short-chain fatty acids that fulfil the many technical constraints of the DNP procedure, as it is today, may limit their clinical potential. New solutions have been sought to circumvent technology-related challenges and facilitate clinical translation of these molecules. In particular, it has been shown that, by using symmetric anhydrides as chemical precursors for short-chain fatty acids, no glass-forming additives are needed in the DNP formulations. Furthermore, novel esterified trityl radicals and lipophilic gadolinium complexes allow easy removal of the polarization-promoting additives at the end of the DNP process. By applying the three concepts reported, we have succeeded in preparing aqueous formulations of short-chain fatty acids for pharmaceutical use that have favourable properties compared with those obtained from current procedures. The use of organic derivatives as chemical precursors of the MCA of interest appears to be a generally valid concept, not restricted to symmetric anhydrides of fatty acids, which can markedly improve the clinical potential of other (13) C-labelled compounds.

Hyperpolarized 1-13C-2-oxoglutarate as contrast agent in13C Magnetic Resonance diagnostic technique (13C-MRI) for use in the diagnosis of cancer. In particular, upon administration of said 1-13C-2-oxoglutarate, signals of 1-13C-glutamate are detected. More in particular, different MR signals from13C nuclei are detected and compared, said comparison being useful to determine a difference between tumor and non-tumor tissues, to determine the aggressiveness of a tumor or the efficacy of an anti-tumor therapy

1-13C-1,1-Bis(acetoxy(methyl))-2,2'-cyclopropane of formula (I): The compound can be hyperpolarized and used as a contrast agent in 13C Magnetic Resonance diagnostic technique (13C-MR) for the diagnosis of tumor.