Asymmetric desymmetrization of meso-diols by C(2)-symmetric chiral 4-pyrrolidinopyridines.

In this work we developed C(2)-symmetric chiral nucleophilic catalysts which possess a pyrrolidinopyridine framework as a catalytic site. Some of these organocatalysts effectively promoted asymmetric desymmetrization of meso-diols via enantioselective acylation

Phototriggered Dehydration Condensation Using an Aminocyclopropenone

金沢大学新学術創成研究機構A phototriggered dehydration condensation using an aminocyclopropenone has been developed. The UV irradiation of an aminocyclopropenone generated a highly reactive ynamine in situ and the dehydration condensation of a carboxylic acid and an amine coexisting in the reaction solution smoothly proceeded to afford an amide. This reaction is completely controllable by the ON/OFF states of a UV lamp. © 2017 American Chemical Society.Embargo Period 12 month

Development of radiogallium-labeled peptides for platelet-derived growth factor receptor β (Pdgfrβ) imaging: Influence of different linkers

金沢大学疾患モデル総合研究センターThe purpose of this study is to develop peptide-based platelet-derived growth factor receptor β (PDGFRβ) imaging probes and examine the effects of several linkers, namely un-natural amino acids (D-alanine and β-alanine) and ethylene-glycol (EG), on the properties of Ga-DOTA(linker)-IPLPPPRRPFFK peptides. Seven radiotracers,67 Ga-DOTA-(linker)-IPLPPPRRPFFK peptides, were designed, synthesized, and evaluated. The stability and cell uptake in PDGFRβ positive peptide cells were evaluated in vitro. The biodistribution of [67 Ga]Ga-DOTA-EG2-IPLPPPRRPFFK ([67 Ga]27) and [67 Ga]Ga-DOTA-EG4-IPLPPPRRPFFK ([67 Ga]28), which were selected based on in vitro stability in murine plasma and cell uptake rates, were determined in BxPC3-luc-bearing nu/nu mice. Seven67 Ga-labeled peptides were successfully synthesized with high radiochemical yields (>85%) and purities (>99%). All evaluated radiotracers were stable in PBS (pH 7.4) at 37◦ C. However, only [67 Ga]27 and [67 Ga]28 remained more than 75% after incubation in murine plasma at 37◦ C for 1 h. [67 Ga]27 exhibited the highest BxPC3-luc cell uptake among the prepared radiolabeled peptides. As regards the results of the biodistribution experiments, the tumor-to-blood ratios of [67 Ga]27 and [67 Ga]28 at 1 h post-injection were 2.61 ± 0.75 and 2.05 ± 0.77, respectively. Co-injection of [67 Ga]27 and an excess amount of IPLPPPRRPFFK peptide as a blocking agent can significantly decrease this ratio. However, tumor accumulation was not considered sufficient. Therefore, further probe modification is required to assess tumor accumulation for in vivo imaging. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This.CC-BY 4.

Synthesis and fundamental evaluation of radioiodinated rociletinib (CO-1686) as a probe to lung cancer with L858R/T790M mutations of Epidermal Growth Factor Receptor (EGFR)

金沢大学疾患モデル総合研究センターRociletinib (CO-1686), a 2,4-diaminopyrimidine derivative, is a highly potent tyrosine kinase inhibitor (TKI) that acts on epidermal growth factor receptor (EGFR) with L858R/T790M mutations. We supposed radioiodinated CO-1686 would function as a useful tool for monitoring EGFR L858R/T790M mutations. To aid in patient selection before therapy with EGFR-TKIs, this study aimed to develop a 125I-labeled derivative of CO-1686, N-{3-[(2-{[4-(4-acetylpiperazin-1-yl)-2-methoxyphenyl]amino}-5-(trifluoromethyl)pyrimidine-4-yl] amino}-5-([125I]iodophenyl)acrylamide ([125I]ICO1686) and evaluate its selectivity toward EGFR L858R/T790M. Radiosynthesis was performed by iododestannylation of the corresponding tributylstannyl precursor with [125I]NaI and N-chlorosuccinimide. The selectivity of the tracer for detecting EGFR L858R/T790M was evaluated using three relevant non-small cell lung cancer (NSCLC) cell lines—H1975, H3255 and H441 overexpressing the dual mutation EGFR L858R/T790M, active mutant EGFR L858R and wild-type EGFR, respectively. The nonradioactive ICO1686 and the precursor compound were successfully synthesized. A novel radiolabeled probe, [125I]ICO1686, was prepared with high radiochemical yield (77%) and purity (>99%). ICO1686 exhibited high cytotoxicity toward H1975 (IC50 0.20 ± 0.05 µM) and H3255 (IC50 0.50 ± 0.21 µM), which is comparable to that of CO-1686. In contrast, the cytotoxicity of ICO1686 toward H441 was 10-fold lower than that toward H1975. In the cell uptake study, the radioactivity uptake of [125I]ICO1686 in H1975 was 101.52% dose/mg, whereas the uptakes in H3255 and H441 were 33.52 and 8.95% dose/mg, respectively. The uptake of [125I]ICO1686 in H1975 was greatly reduced to 45.61% dose/mg protein by treatment with excess CO-1686. In vivo biodistribution study of the radiotracer found that its accumulation in H1975 tumor (1.77 ± 0.43% ID/g) was comparable to that in H3255 tumor (1.63 ± 0.23% ID/g) and the accumulation in H1975 tumor was not reduced by pretreatment with an excess dose of CO-1686. Although this radiotracer exhibited highly specific in vitro uptake in target cancer cells, structural modification is required to improve in vivo biodistribution. © 2020 by the authors.This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

Synthesis and evaluation of a dimeric rgd peptide as a preliminary study for radiotheranostics with radiohalogens

金沢大学疾患モデル総合研究センターWe recently developed125I-and211At-labeled monomer RGD peptides using a novel radi-olabeling method. Both labeled peptides showed high accumulation in the tumor and exhibited similar biodistribution, demonstrating their usefulness for radiotheranostics. This study applied the labeling method to a dimer RGD peptide with the aim of gaining higher accumulation in tumor tissues based on improved affinity with αvβ3 integrin. We synthesized an iodine-introduced dimer RGD peptide, E[c(RGDfK)] (6), and an 125/131 I-labeled dimer RGD peptide, E[c(RGDfK)]{[125/131I]c[RGDf(4-I)K]} ([125/131I]6), and evaluated them as a preliminary step to the synthesis of an211At-labeled dimer RGD peptide. The affinity of 6 for αvβ3 integrin was higher than that of a monomer RGD peptide. In the biodistribution experiment at 4 h postinjection, the accumulation of [125I]6 (4.12 ± 0.42% ID/g) in the tumor was significantly increased compared with that of125I-labeled monomer RGD peptide (2.93 ± 0.08% ID/g). Moreover, the accumulation of [125I]6 in the tumor was greatly inhibited by co-injection of an excess RGD peptide. However, a single injection of [131I]6 (11.1 MBq) did not inhibit tumor growth in tumor-bearing mice. We expect that the labeling method for targeted alpha therapy with211At using a dimer RGD peptide could prove useful in future clinical applications. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.CC-BY 4.

A radiobrominated tyrosine kinase inhibitor for egfr with l858r/t790m mutations in lung carcinoma

金沢大学疾患モデル総合研究センターActivating double mutations L858R/T790M in the epidermal growth factor receptor (EGFR) region are often observed as the cause of resistance to tyrosine kinase inhibitors (TKIs). Third‐generation EGFR‐TKIs, such as osimertinib and rociletinib (CO‐1686), was developed to target such resistance mutations. The detection of activating L858R/T790M mutations is necessary to select sensitive patients for therapy. Hence, we aimed to develop novel radiobromine‐labeled CO‐ 1686 as a positron emission tomography (PET) imaging probe for detecting EGFR L858R/T790M mutations. Nonradioactive brominated‐CO1686 (BrCO1686) was synthesized by the condensation of N‐(3‐[{2‐chloro‐5‐(trifluoromethyl)pyrimidin‐4‐yl}amino]‐5‐bromophenyl) acrylamide with the corresponding substituted 1‐(4‐[4‐amino‐3‐methoxyphenyl]piperazine‐1‐yl)ethan‐1‐one. The radi-obrominated [77 Br]BrCO1686 was prepared through bromodestannylation of the corresponding tributylstannylated precursor with [77Br]bromide and N‐chlorosuccinimide. Although we aimed to provide a novel PET imaging probe,77Br was used as an alternative radionuclide for76Br. We fun-damentally evaluated the potency of [77Br]BrCO1686 as a molecular probe for detecting EGFR L858R/T790M using human non‐small‐cell lung cancer (NSCLC) cell lines: H1975 (EGFR L858R/T790M), H3255 (EGFR L858R), and H441 (wild‐type EGFR). The BrCO1686 showed high cy-totoxicity toward H1975 (IC50 0.18 ± 0.06 μM) comparable to that of CO‐1686 (IC50 0.14 ± 0.05 μM). In cell uptake experiments, the level of accumulation of [77Br]BrCO1686 in H1975 was significantly higher than those in H3255 and H441 upon 4 h of incubation. The radioactivity of [77Br]BrCO1686 (136.3% dose/mg protein) was significantly reduced to 56.9% dose/mg protein by the pretreatment with an excess CO‐1686. These results indicate that the binding site of the radiotracers should be identical to that of CO‐1686. The in vivo accumulation of radioactivity of [77Br]BrCO1686 in H1975 tumor (4.51 ± 0.17) was higher than that in H441 tumor (3.71 ± 0.13) 1 h postinjection. Our results suggested that [77Br]BrCO1686 has specificity toward NSCLC cells with double mutations EGFR L858R/T790M compared to those in EGFR L858R and wild‐type EGFR. However, the in vivo accumulation of radioactivity in the targeted tumor needs to be optimized by structural modification. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.CC-BY 4.

Decreasing undesirable absorbed radiation to the intestine after administration of radium-223 dichloride for treatment of bone metastases

金沢大学疾患モデル総合研究センター[223Ra]RaCl2 is the first alpha-particle emitting radiopharmaceutical to be used for castration-resistant prostate cancer patients with bone metastases because of its excellent therapeutic effects. [223Ra]RaCl2 is excreted via the intestine into feces, and some is absorbed from the intestine into the blood, which may be undesirable in terms of the exposure to radiation. Recently, we showed that a complex of myo-inositol-hexakisphosphate (InsP6) with zinc is a useful decorporation agent against radiostrontium. In this study, we hypothesized that Zn-InsP6 could bind to not only strontium but also to radium, and could inhibit the absorption of radium from the intestine. In in vitro binding experiments, Zn-InsP6 showed a high binding affinity for radium. In in vivo biodistribution experiments by intravenous injection of [223Ra]RaCl2 after treatment of Zn-InsP6, mice treated with Zn-InsP6 showed significantly lower bone accumulation of radioactivity (34.82 ± 1.83%Dose/g) than the mice in the non-treatment control group (40.30 ± 2.78%Dose/g) at 48 h postinjection. These results indicate that Zn-InsP6 bound radium in the intestine and inhibited the absorption of radium into the blood. Therefore, the insoluble Zn-InsP6 complex has high potential to decrease the side effects of [223Ra]RaCl2. © 2020, The Author(s)

Radiotheranostics coupled between an At-211-Labeled RGD peptide and the corresponding radioiodine-labeled RGD peptide

金沢大学疾患モデル総合研究センターAlpha particle-emitting radionuclides have gained considerable attention for radionuclide therapy. Astatine-211 ( 211 At) is a promising alpha particle-emitting radionuclide. 211 At is a halogen that has similar chemical properties to iodine and exhibits a half-life of 7.2 h. However, direct labeling of proteins or peptides into the tyrosine residue with 211 At was shown to be impractical. Herein, we demonstrate a novel 211 At-labeling method using the RGD peptide as a model peptide. An 211 At-labeled RGD peptide, [ 211 At]c[RGDf(4-At)K], was prepared from a precursor with a tributylstannyl group on the phenylalanine residue in c(RGDfK) with a radiochemical yield of 63% and a radiochemical purity of >96%, and its potential for targeted radionuclide therapy was evaluated. Based on the results of biodistribution experiments, [ 125 I]c[RGDf(4-I)K] and [ 211 At]c[RGDf(4-At)K] showed high accumulation in the tumor and similar biodistribution. This study provides useful information for radiotheranostics between an 211 At-labeled peptide and the corresponding radioiodine-labeled peptide. © 2019 American Chemical Society.This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes

Synthesis and evaluation of radioiodinated 1-(2-[5-(2-methoxyethoxy)-1H-benzo[d]imidazol-1-yl]quinolin-8-yl)piperidin-4-amine derivatives for platelet-derived growth factor receptor β (PDGFRβ) imaging

金沢大学新学術創成研究機構Platelet-derived growth factor receptor β (PDGFRβ) is a transmembrane tyrosine kinase receptor and it is upregulated in various malignant tumors. Radiolabeled PDGFRβ inhibitors can be a convenient tool for the imaging of tumors overexpressing PDGFRβ. In this study, [125I]-1-(5-iodo-2-[5-(2-methoxyethoxy)-1H-benzo[d]imidazol-1-yl]quinoline-8-yl)piperidin-4-amine ([125I]IIQP) and [125I]-N-3-iodobenzoyl-1-(2-[5-(2-methoxyethoxy)-1H-benzo[d]imidazol-1-yl]quinolin-8-yl)-piperidin-4-amine ([125I]IB-IQP) were designed and synthesized, and their potential as PDGFRβ imaging agents was evaluated. In cellular uptake experiments, [125I]IIQP and [125I]IB-IQP showed higher uptake by PDGFRβ-positive cells than by PDGFRβ-negative cells, and the uptake in PDGFRβ-positive cells was inhibited by co-culture with PDGFRβ ligands. The biodistribution of both radiotracers in normal mice exhibited hepatobiliary excretion as the main route. In mice inoculated with BxPC3-luc (PDGFRβ-positive), the tumor uptake of radioactivity at 1h after the injection of [125I]IIQP was significantly higher than that after the injection of [125I]IB-IQP. These results indicated that [125I]IIQP can be a suitable PDGFRβ imaging agent. However, further modification of its structure will be required to obtain a more appropriate PDGFRβ-targeted imaging agent with a higher signal/noise ratio. © 2017.Embargo Period 12 month

Radiobrominated benzimidazole-quinoline derivatives as Platelet-derived growth factor receptor beta (PDGFRβ) imaging probes

金沢大学疾患モデル総合研究センターPlatelet-derived growth factor receptor beta (PDGFRβ) affects in numerous human cancers and has been recognized as a promising molecular target for cancer therapies. The overexpression of PDGFRβ could be a biomarker for cancer diagnosis. Radiolabeled ligands having high affinity for the molecular target could be useful tools for the imaging of overexpressed receptors in tumors. In this study, we aimed to develop radiobrominated PDGFRβ ligands and evaluate their effectiveness as PDGFRβ imaging probes. The radiolabeled ligands were designed by modification of 1-{2-[5-(2-methoxyethoxy)-1H- benzo[d]imidazol-1-yl]quinolin-8-yl}piperidin-4-amine (1), which shows selective inhibition profile toward PDGFRβ. The bromine atom was introduced directly into C-5 of the quinoline group of 1, or indirectly by the conjugation of 1 with the 3-bromo benzoyl group. [77Br]1-{5-Bromo-2-[5-(2-methoxyethoxy)-1H-benzo[d]imidazol-1-yl]quinoline-8-yl}piperidin-4-amine ([77Br]2) and [77Br]-N-3-bromobenzoyl-1-{2-[5-(2-methoxyethoxy)-1H-benzo[d]imidazol-1-yl]quinolin-8-yl}-piperidin-4-amine ([77Br]3) were prepared using a bromodestannylation reaction. In a cellular uptake study, [77Br]2 and [77Br]3 more highly accumulatd in BxPC3-luc cells (PDGFRβ-positive) than in MCF7 cells (PDGFRβ-negative), and their accumulation was significantly reduced by pretreatment with inhibitors. In biodistribution experiments, [77Br]2 accumulation was higher than [77Br]3 accumulation at 1 h postinjection. These findings suggest that [76Br]2 is more promising for positron emission tomography (PET) imaging of PDGFRβ than [76Br]3. © 2018 The Author(s).CC-BY 4.