Name: preparation and evaluation of 99mtc-labeled tridentate chelates for pre-targeting using bioorthogonal chemistry
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Description: Watch this Scientific Journal Video about Preparation and Evaluation of 99mTc-labeled Tridentate Chelates for Pre-targeting Using Bioorthogonal Chemistry at JoVE.com

This work supported by research grant funding from the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Ontario Institute for Cancer Research (OICR, #P.SI.015.8), and the Canadian Cancer Society (CCS, #703857). The authors acknowledge the contributions of Dr. Denis Snider who provided assistance in preparing the manuscript.

Hayvan çalışmaları Hayvan Bakımı Kanada Konseyi (ccac) kurallara uygun olarak McMaster Üniversitesi Hayvan Araştırmaları Etik Kurulu tarafından onaylanmıştır. 99m Tc ile Tz-üç dişli Ligandlar 1. Radyo-etiketlenmesi DİKKAT: Aşağıdaki prosedürler radyoaktif bileşikler kullanılmasını gerektirir. İş sadece güvenliği ve atılması düzenlemelerine bağlılık ile lisanslı laboratuarda yapılmalıdır. Mikrodalga reaksiyonları, özellikle, kimyasal sentez için tasarlanmış mikrodalga yapılmalıdır. <ol><li> Sentezi [99mTc (CO) 3 (H2O) 3] + 19, 20 <ol><li> Bir mikrodalga şişeye olarak, kombine 8 mg K 2 [BH3 CO2], 15 mg Na 2 CO 3, 20 mg Na 2 B 4 O 7 · 10H 2, O, 25 mg KOCO [CH (OH)]2 COONa · 4H 2 O Boşaltma argon gazı ile 10 dakika boyunca bir tüpe konulmuştur. </li><li> Şişeye% 0.9 tuzlu su içinde (~ 1.100 MBq, ~ 30 mCi) - toplam maliyet masrafı 4 99m 4 ml. </li><li> reaktiflerin bir karışım elde etmek karıştırma 10 saniye sonra, 110 ° C&#39;de 3.5 dakika boyunca bir mikrodalga reaksiyon ısı. </li><li> ~ 400 uL 1 M HCI kullanılarak 3.5-4 çözeltinin pH&#39;ının ayarlanması. pH kağıdı kullanarak doğrulayın. </li></ol></li><li> Tetrazin radyo-etiketlenmesi, 1-5 ligandları <ol><li> 250 uL, MeOH 21 her ligandın 2 mg (bileşikler 1-5) içinde çözülür. </li><li> 250 uL ekleyin [99m Tc (CO) 3 (H 2 O) 3] + (~ 74 MBq ~ 2 mCi) her çözüm. </li><li> 60 ° C&#39;de 20 dakika boyunca bir mikrodalga kullanarak reaksiyon karışımı ısıtılır. Not: Bu adım, tüm 5 tetrazinler için aynıydı. </li><li> Bileşikler 2-5 için, solvent ve yeniden dissol buharlaşması1 h / h, DCM: TFA 1 1 mL elde edilen ürünler ve. </li><li> 6 dakika boyunca (2-4) ya da 10 dakika (5) için bir mikrodalga içinde 60 ° C sıcaklıkta çözülmüş, reaksiyon ürünleri (2-5) ısıtın. </li><li> Oda sıcaklığına kadar soğutulduktan sonra, bir buharlaştırıcı kullanılarak çözücü (36 ° C, 8 mbar, 3 dakika, 6000 rpm) ve buharlaştınlarak 1 kurutulmuştur bileşiği çözmek: 1 ACN: H2, O ya da 1: 1 MeOH: H2O, HPLC ile arıtma öncesi. </li><li> HPLC (C18 ters fazlı) ile, etiketlenmemiş tetrazin ligand etiketli ürünün ayrılması dahil olmak üzere, 99mTc-etiketli bileşikler (1-5), saflaştınlır. Tipik haliyle, 30:70 ACN gradyanı kullanılmaktadır: H2O (her ikisi de% 0.1 TFA ile birlikte) 40:60 ACN: H2O 20 dakika boyunca (18 dakika) ve bir C18 analitik 4.6 x 100 mm kolonu üzerinde. UV (254 nm) ve gama algılama hem de kullanın. <ol><li> Her bir işaretlenmiş ürünün küçük bir örneği alın ve bir ko-inj edilene olan HPLC alıkoyma süresi karşılaştırınyansıtılmaktadır, radyoaktif olmayan, standart yeniden etiketli (% 20 0.125 mg metanol-H2O). Yeniden etiketli standart bir UV HPLC izi tespit edilir ve γ-HPLC izleme 99mTc-etiketli bileşik ile aynı zamanda Zehir. Bu ko-enjeksiyon bileşik Tc-etiketli 99m kimliğini doğrulayan, karşılaştırılabilir tutma zamanlarda doruklarını gösterir. </li></ol></li><li> bir evaporatör (36 ° C, 8 mbar, 3 dakika, 6000 rpm) kullanılarak HPLC fraksiyonlardan çözücü buharlaşır. </li><li> % 0.5 BSA ve% 0.01 Tween-80 ihtiva eden, 7,4 kBq / PBS uL konsantrasyonunda saflaştırılarak bileşik formüle. </li><li> Etiketli bileşikler stabil olmasını sağlamak için, bir in vitro stabilitesi çalışma gerçekleştirin. stabilitesini değerlendirmek için, her zaman noktasında HPLC karışımın küçük bir miktar (3.7 MBq) enjekte, 1, 4 ve 6 saat boyunca 37 ° C &#39;de formüle edilen bileşiğin inkübe edin. </li></ol></li></ol> 2. Ön hedefli Bio-dağıtım Çalışmaları <ol><lHayvanların i&gt; hazırlanması <ol><li> 7-9 haftalık dişi Balb / c fareleri kullanılarak (n = 3), kuyruk ven enjeksiyon yoluyla TCO BP tuzlu su (20 mg / kg) (5 ug / ml) içinde formüle uygulanması. </li><li> fiziksel kısıtlama cihaz fare yerleştirin ve kuyruk yan yüzeylerinde bulunan damarları belirlemek ve alkollü bir bezle silin. kuyruk ucundan yaklaşık 2 cm, ven sığ bir açı paralel bir 30-gauge iğne takın. Yavaşça, enjekte iğneyi çıkarın ve kanama durana kadar hafif basınç ile enjeksiyon yerinde temiz gazlı bez sünger uygulamak için piston bastırın. </li><li> TCO-BP 1 saat sonra enjeksiyon da tatbik ~% 0.5 BSA, 100 uL içinde formüle 99mTc-tetrazin 0.74 MBq (20 uCi),% 0.01 Tween-80, PBS içinde, kuyruk ven enjeksiyon yoluyla. </li></ol></li><li> Biyo-dağılım çalışmaları <ol><li> İstenilen zaman noktasında (t = 6 saat),% 3 izofluran ve% 2 oksijen gaz karışımı kullanılarak Fareler uyuşturan. bir gösterinanestezi fare e tutam çekilme anestezi cerrahi düzlemine altında olduğundan emin olmak için. </li><li> bir şırınga heparin ile ön-muamele ile kalp ponksiyonu ile kanı (1 mL) içinde toplayın. devam anestezi burun konisi burun sırtında yer fare ve hayvan üzerinde kılıç şeklinde sürecini bulun. <ol><li> 20 ° açıyla biraz kılıç şeklinde süreci kapsamında hayvanın orta hatta sol, 25 G iğne takın. Tam iğneyi ve yavaş yavaş kalp delinmiş eğer iğne hub kan görmek için piston geri çekin. Gerekirse kalbi delmek, dalgıç tutarken biraz iğneyi yeniden ayarlayın. Yavaş yavaş şırınga içine kan çizmek. </li></ol></li><li> anestezi altında iken, servikal dislokasyon ile hayvan Euthanize. </li><li> Bir plastik torba içinde her hayvan koyun ve tüm vücut aktivite düzeyini ölçmek için bir doz kalibrasyon cihazı (99m Tc ayarı) kullanın. </li><li> aşağıdaki doku ve sıvı toplama öncesi ağırlığındakan, kemik (diz ve omuz), safra kesesi, böbrekler, karaciğer, (içindekiler) ile mide, (içindekiler) ile ince bağırsak, kalın bağırsak ve (içeriği ile) caecum, tiroid ve trakea, idrar ile idrar kesesi: ed tüpleri sayma ve kuyruk. </li><li> Uygun sayım tüpleri dokuları yerleştirmeden önce kan kaldırmak ve kuru leke PBS (kan, safra kesesi ve idrar kesesi hariç) uygun dokuları durulayın. </li><li> plastik bir torbaya hayvan karkas yerleştirin ve bir doz kalibratörü ile artık tüm vücut aktivitesini ölçmek. </li><li> Doku örneği içeren her tüp tartılır. Tüpün çıkarma başlangıç ​​ağırlık doku kütlesi elde edilmiştir. </li><li> Her bir fare için enjeksiyon esnasında bir test numunesi (100 uL) etkinlik miktarını ölçmek için, bir doz kalibrasyon cihazı (99mTc ayarı) kullanın. Not: Bu test örneği, böylece enjeksiyon esnasında aktivite sayımı veren enjeksiyon hacmine eşittir. </li><li> Doku ölçümü bir zamandadaha önce kullanılmış olan test örneğinin liquot 5 uL. Bir çok dedektörlü gama sayacı (99m Tc ayarı) kullanın ve 5 uL test örneği için dakika (CPM) başına sayımı elde etmek saymak. </li><li> Bir dönüşüm faktörü (CPM uCi -1) elde etmek için denklem 1 kullanılarak aktivite ve CPM ilişkiyi hesaplamak için 2.2.9 ve 2.2.10 elde edilen iki değer kullanın. (1) <img alt="denklem 1" src="/files/ftp_upload/55188/55188eq1.jpg" /></li><li> Her bir doku veya sıvı örneğinde radyoaktivite miktarını ölçmek için gama sayacını kullanın. </li><li> toplam enjekte edilen dozun ölçüm nisbetle zamanda her bir doku veya akışkan içinde etkinlik miktarını hesaplamak için Denklem 1 kullanın. Bu değer daha sonra, organ ağırlığı ile normalize ve doku gramı başına enjekte edilen doz yüzdesi (yani,% ID / g) olarak rapor edilir. </li><li> Absen 99m Tc-etiketli tetrazin ligandlar kullanılarak negatif kontrol deney yapmak için adımları 2.2.13&#39;ün için 2.1.2 izleyinTCO-BP ce. Kurban fareleri (n = 3) ve 0.5, 1, 4 ve 6 saat sonra enjeksiyonda doku ya da yukarıda tarif edildiği gibi sıvı elde. </li></ol></li></ol>

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The authors declare they have no competing financial interests.

Farklı kutuplar tetrazin-bağlı üç dişli şelatların koleksiyonu hazırlandı ve in vivo olarak bir TCO türevi ile IEDDA reaksiyonunda kendi 99mTc komplekslerinin yardımcı değerlendirildi. Etkili ve tekrarlanabilir 99mTc etiketleme yöntemi ligand konsantrasyonu etiketleme adım (Bileşikler 2-5), t-butil gruplarının korumasının kaldırılması izledi 10 -3 M, beş tetrazin-çelatları için geliştirilmiştir. Ligandın konsantrasyonu yü...

99m Tc dünya çapında yılda 1, 2, 3 başına yapılan 50 milyon görüntüleme işlemleri ile teşhis nükleer tıpta kullanılan baskın radyoizotop kalır. Klinik olarak kullanılan 99m Tc ajanların çoğunluğu perfüzyon tipi radyofarmosötik. 99mTc, bir hedef yapıya ligasyon aracılığıyla belirli bir biyomarker bağlamak için yönlendirildiği aktif hedef bileşiklerin sınırlı vardır. Hedeflenen 99m Tc radyofarmasötik oluşturulması genellikle ilgi biyobelirteci bağlamak için hedef molekülün yeteneği 99m Tc-ligand komplekslerinin etkisiyle tarafından engellendiği ya da izotoplar yarı ömrü daha yüksek molekül ağırlıklı biyomoleküllerin kullanım için yeterince uzun değildir antikorlar gibi. görüntüleri Tiss olmayan hedefinden temizlemek biyomolekülün için sırayla edinilen önce ikincisi genellikle birkaç gün gerektirir<html> ues. Ön hedefleme bu zorlukların üstesinden gelmek için alternatif bir yaklaşım sunuyor. Bioorthogonal kimya ile birlikte ön hedefleme hem floresan ve radyo-görüntüleme 4, 5, 6, 7, 8 yeni moleküler görüntüleme probları geliştirmek için etkili bir yol olduğu görülmüştür. Şekil 1 &#39;de gösterildiği gibi, 1,2,4,5-tetrazin (Tz) ve trans -cyclooctene (TCO) türevleri arasında ters elektron talebi Diels-Alder (IEDDA) Reaksiyon, 6, özellikle etkili olduğu gösterilmiştir. Bu bileşenleri ile IEDDA reaksiyonu ve yüksek seçicilik, in vivo ön hedefleme uygulamalar 9, 10 için idealdir (2 ≈ 6,000 M -1 s -1 k) PBS içinde hızlı kinetik sergileyebilirler. e_content &quot;&gt; en sık kullanılan yaklaşım TCO türetilen hedefleme vektör uygulanması ve yeterli bir gecikme süresinden sonraki kapsar, bir radyo-etiketli tetrazin uygulanır. Radyoaktif tetrazinler olmuştur 11 ° C, 18 F, 64 Cu, 89 Zr ve 111 In dayalı , 13, 12, 11, 14, 15 bildirilmiştir. Buna karşın, in vivo olarak proteine bozulmasını önlemek için ko-ligand kullanımını gerektiren HYNIC tipi ligand kullanılarak hazırlanmıştır Tz Tc-99m etiketli, tek yayın vardır 16. bir alternatif olarak, + çekirdek [3 99mTc (CO)], bir kararlı üç dişli kompleksleri oluşturan bağların bir ailesi kullanılarak tetrazinler etiketli burada 99mTc (I) &#39;in sentezi açıklanmıştır. Şekil 1: tetrazin ve trans -cyclooctene arasındaki bioorthogonal IEDDA reaksiyonu. <a href="https://ecsource-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/55188/55188fig1large.jpg" target="_blank">Bu rakamın büyük halini görmek için lütfen buraya tıklayınız.</a> Hazırlanan ligandlar ailesi polarite ve metal bağlanma bölgesi ve Tz (Şekil 2) arasında bağlayıcı grubun doğasına değişir üç dişli şelatları içerir. Amaç, yüksek hedef-to-hedef dışı oranları elde etmek amacıyla, Tc-tetrazin etkin bir şekilde lokalize ve TCO-etiketli in vivo siteleri ve bağlı değilken hızla net ile reaksiyona olabilir inşa eden 99m belirlemektir. Ligandları test etmek için, bir bisfosfonat bir TCO-türevi (TCO-BP) 17 kullanılmıştır. Bu TCO-BP aktif kemik metabolizmasının bölgelerine lokalize ile reaksiyona girerek daha önce göstermiştirin vivo 18 radyo-etiketli tetrazinler. Bu tek bir aşamada hazırlanabilir ve deneyler lokalizasyon esas olarak eklem (diz ve omuz) meydana gelir, normal farelerde gerçekleştirilebilir, çünkü yeni bir tetrazinler test etmek için uygun bir reaktiftir.

<table><tbody><tr><td>Argon gas</td><td>Alphagaz</td><td>---</td><td>---</td></tr><tr><td>Na&lt;sub&gt;2&lt;/sub&gt;CO&lt;sub&gt;3&lt;/sub&gt;</td><td>EMD Millipore</td><td>106395</td><td>---</td></tr><tr><td>Na&lt;sub&gt;2&lt;/sub&gt;B&lt;sub&gt;4&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt;&amp;#183;10H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Anachemia</td><td>S9640</td><td>---</td></tr><tr><td>KNaC&lt;sub&gt;4&lt;/sub&gt;H&lt;sub&gt;4&lt;/sub&gt;O&lt;sub&gt;6&lt;/sub&gt;&amp;#183;4H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Anachemia</td><td>217255</td><td>---</td></tr><tr><td>Technelite &lt;sup&gt;99m&lt;/sup&gt;Tc generator</td><td>Lantheus medical imaging</td><td>---</td><td>Source of &lt;sup&gt;99m&lt;/sup&gt;TcO&lt;sup&gt;4-&lt;/sup&gt;</td></tr><tr><td>0.9% Saline</td><td>Lantheus medical imaging</td><td>---</td><td>To elute generator</td></tr><tr><td>1 M HCl</td><td>Lab Chem</td><td>---</td><td>---</td></tr><tr><td>MeOH</td><td>Caledon</td><td>---</td><td>---</td></tr><tr><td>ACN</td><td>Caledon</td><td>---</td><td>HPLC grade</td></tr><tr><td>Millipore H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Thermo Fisher Scientific</td><td>Barnstead Nanopure</td><td>---</td></tr><tr><td>DCM</td><td>Caledon</td><td>---</td><td>---</td></tr><tr><td>TFA</td><td>Caledon</td><td>---</td><td>---</td></tr><tr><td>PBS</td><td>Thermo Fisher Scientific</td><td>10010023</td><td>pH 7.4 1x</td></tr><tr><td>BSA</td><td>Sigma Aldrich</td><td>A7906</td><td>---</td></tr><tr><td>Tween80</td><td>Sigma Aldrich</td><td>P8047</td><td>---</td></tr><tr><td>Isoflurane</td><td>CDMV</td><td>108737</td><td>Supplier: Fresenius Kabi Animal Health</td></tr><tr><td>HPLC</td><td>Waters</td><td>1525 Binary Pump, 2998 Photodiodde Array Detector, E-SAT/IN, Bioscan Flowcount PMT detector (item # 15590)</td><td>---</td></tr><tr><td>HPLC column for analysis and purification of compounds 2-4</td><td>Phenomenex</td><td>00G-4435-E0</td><td>Gemini&amp;reg; 5 &amp;micro;m C18 110&amp;nbsp;&amp;Aring;, LC Column 250 x 4.6 mm</td></tr><tr><td>HPLC column for analysis and purification of compounds 1 and 5</td><td>Waters&amp;nbsp;</td><td>186003115</td><td>XBridge BEH C18 Column, 130 &amp;Aring;, 5 &amp;micro;m, 4.6 mm x 100 mm</td></tr><tr><td>Microwave Reactor&amp;nbsp;</td><td>Biotage&amp;nbsp;</td><td>Initiator 8</td><td>---</td></tr><tr><td>Biotage V10 Evaporator</td><td>Biotage&amp;nbsp;</td><td>Serial # V1041</td><td>---</td></tr><tr><td>Dose calibrator</td><td>Capintec, Inc.&amp;nbsp;</td><td>CRC-25R</td><td>---</td></tr><tr><td>Gamma counter</td><td>Perkin Elmer</td><td>Wizard 1470 Automatic Gamma Counter</td><td>---</td></tr><tr><td>Animal room scale&amp;nbsp;</td><td>Mettler Toledo</td><td>XP105 Delta Range</td><td>---</td></tr><tr><td>Microwave vials&amp;nbsp;</td><td>Biotage&amp;nbsp;</td><td>355629</td><td>0.5-2 mL&amp;nbsp;</td></tr></tbody></table>

preparation and evaluation of 99mtc-labeled tridentate chelates for pre-targeting using bioorthogonal chemistry

Pre-targeting combined with bioorthogonal chemistry is emerging as an effective way to create new radiopharmaceuticals. Of the methods available, the inverse electron demand Diels-Alder (IEDDA) cycloaddition between a radiolabeled tetrazines and trans-cyclooctene (TCO) linked to a biomolecule has proven to be a highly effective bioorthogonal approach to imaging specific biological targets. Despite the fact that technetium-99m remains the most widely used isotope in diagnostic nuclear medicine, there is a scarcity of methods for preparing 99mTc-labeled tetrazines. Herein we report the preparation of a family of tridentate-chelate-tetrazine derivatives and their Tc(I) complexes. These hitherto unknown compounds were radiolabeled with 99mTc using a microwave-assisted method in 31% to 83% radiochemical yield. The products are stable in saline and PBS and react rapidly with TCO derivatives in vitro. Their in vivo pre-targeting abilities were demonstrated using a TCO-bisphosphonate (TCO-BP) derivative that localizes to regions of active bone metabolism or injury. In murine studies, the 99mTc-tetrazines showed high activity concentrations in knees and shoulder joints, which was not observed when experiments were performed in the absence of TCO-BP. The overall uptake in non-target organs and pharmacokinetics varied greatly depending on the nature of the linker and polarity of the chelate.

Ligandlar ticari olarak temin edilebilen tetrazin 22, 23, ürünün bağlanması ve ardından basit bir indirgeyici aminasyon stratejisi (Şekil 2), üzerinden farklı bağlayıcılar ve kenetleyiciler kullanılarak sentezlenmiştir. Radyo-etiketlenmesi bütün bileşikler aynı yöntem kullanılarak gerçekleştirilir ve yüksek oranda çoğaltılabilir oldu. % 83 (1),% 45 (2),%...

Watch this Scientific Journal Video about Preparation and Evaluation of 99mTc-labeled Tridentate Chelates for Pre-targeting Using Bioorthogonal Chemistry at JoVE.com

Preparation and Evaluation of 99mTc-labeled Tridentate Chelates for Pre-targeting Using Bioorthogonal Chemistry

Here, we describe a protocol for radiolabeling and in vivo testing of tridentate 99mTc(I) chelate-tetrazine derivatives for pre-targeting and bioorthogonal chemistry.

Hazırlama ve Değerlendirilmesi<sup&gt; 99m</sup&gt; Bioorthogonal Kimya Kullanarak Öncesi hedeflemek için üç dişli Şelatlar Tc-etiketli

Pre-targeting combined with bioorthogonal chemistry is emerging as an effective way to create new radiopharmaceuticals. Of the methods available, the ...

preparation-evaluation-99mtc-labeled-tridentate-chelates-for-pre

Universidad San Sebastian

Research

JoVE Journal

Chemistry

Preparation and Evaluation of 99mTc-labeled Tridentate Chelates for Pre-targeting Using Bioorthogonal Chemistry

8.1K Görüntüleme.  McMaster University. Here, we describe a protocol for radiolabeling and in vivo testing of tridentate 99mTc(I) chelate-tetrazine derivatives for pre-targeting and bioorthogonal chemistry. 

Video: Preparation and Evaluation of 99mTc-labeled Tridentate Chelates for Pre-targeting Using Bioorthogonal Chemistry

Microfluidic On-chip Capture-cycloaddition Reaction to Reversibly Immobilize Small Molecules or Multi-component Structures for Biosensor Applications

Methods for rapid surface immobilization of bioactive small molecules with control over orientation and immobilization density are highly desirable for biosensor and microarray applications. In this Study, we use a highly efficient covalent bioorthogonal [4+2] cycloaddition reaction between trans-cyclooctene (TCO) and 1,2,4,5-tetrazine (Tz) to enable the microfluidic immobilization of TCO/Tz-derivatized molecules. We monitor the process in real-time under continuous flow conditions using surface plasmon resonance (SPR). To enable reversible immobilization and extend the experimental range of the sensor surface, we combine a non-covalent antigen-antibody capture component with the cycloaddition reaction. By alternately presenting TCO or Tz moieties to the sensor surface, multiple capture-cycloaddition processes are now possible on one sensor surface for on-chip assembly and interaction studies of a variety of multi-component structures. We illustrate this method with two different immobilization experiments on a biosensor chip; a small molecule, AP1497 that binds FK506-binding protein 12 (FKBP12); and the same small molecule as part of an immobilized and in situ-functionalized nanoparticle.

We present a method for rapid, reversible immobilization of small molecules and functionalized nanoparticle assemblies for Surface Plasmon Resonance (SPR) studies, using sequential on-chip bioorthogonal cycloaddition chemistry and antibody-antigen capture.

Tersi Küçük Moleküller veya Biosensor Uygulamaları için Çok bileşenli Yapılar hareketsiz için microfluidic On-chip Yakalama sikloeklenme Tepki

Methods  for rapid surface immobilization of bioactive small molecules with control over  orientation and immobilization density are highly desirable for ...

Kimya

The Bioconjugation and Radiosynthesis of 89Zr-DFO-labeled Antibodies

The exceptional affinity, specificity, and selectivity of antibodies make them extraordinarily attractive vectors for tumor-targeted PET radiopharmaceuticals. Due to their multi-day biological half-life, antibodies must be labeled with positron-emitting radionuclides with relatively long physical decay half-lives. Traditionally, the positron-emitting isotopes 124I (t1/2 = 4.18 d), 86Y (t1/2 = 14.7 hr), and 64Cu (t1/2 = 12.7 hr) have been used to label antibodies for PET imaging. More recently, however, the field has witnessed a dramatic increase in the use of the positron-emitting radiometal 89Zr in antibody-based PET imaging agents. 89Zr is a nearly ideal radioisotope for PET imaging with immunoconjugates, as it possesses a physical half-life (t1/2 = 78.4 hr) that is compatible with the in vivo pharmacokinetics of antibodies and emits a relatively low energy positron that produces high resolution images. Furthermore, antibodies can be straightforwardly labeled with 89Zr using the siderophore-derived chelator desferrioxamine (DFO). In this protocol, the prostate-specific membrane antigen targeting antibody J591 will be used as a model system to illustrate (1) the bioconjugation of the bifunctional chelator DFO-isothiocyanate to an antibody, (2) the radiosynthesis and purification of a 89Zr-DFO-mAb radioimmunoconjugate, and (3) in vivo PET imaging with an 89Zr-DFO-mAb radioimmunoconjugate in a murine model of cancer.

The Bioconjugation and Radiosynthesis of 89Zr-DFO-labeled Antibodies

Due to its multi-day radioactive half-life and favorable decay properties, the positron-emitting radiometal 89Zr is extremely well-suited for use in antibody-based radiopharmaceuticals for PET imaging. In this protocol, the bioconjugation, radiosynthesis, and preclinical application of 89Zr-labeled antibodies will be described.

Bioconjugation ve radiosynthesis<sup&gt; 89</sup&gt;, Zr-DFO-etiketli antikorlar

The exceptional affinity, specificity, and selectivity of antibodies make them extraordinarily attractive vectors for tumor-targeted PET ...

An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125I-labeled azide prosthetic group and its application to the efficient radiolabeling of DBCO-group-functionalized gold nanoparticles using a copper-free click reaction. Radioiodination of the stannylated precursor (2) was carried out by using [125I]NaI and chloramine T as an oxidant at room temperature for 15 min. After HPLC purification of the crude product, the purified 125I-labeled azide (1) was obtained with high radiochemical yield (75 &plusmn; 10%, n = 8) and excellent radiochemical purity (&gt;99%). For the synthesis of radiolabeled 13-nm-sized gold nanoparticles, the DBCO-functionalized gold nanoparticles (3) were prepared by using a thiolated polyethylene glycol polymer. A copper-free click reaction between 1 and 3 gave the 125I-labeled gold nanoparticles (4) with more than 95% of radiochemical yield as determined by radio-thin-layer chromatography (radio-TLC). These results clearly indicate that the present radiolabeling method using a strain-promoted copper-free click reaction will be useful for the efficient and convenient radiolabeling of DBCO-group-containing nanomaterials.

An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group

A detailed procedure for the synthesis of a 125I-labeled azide and the radiolabeling of dibenzocyclooctyne (DBCO)-group-conjugated, 13-nm-sized gold nanoparticles using a copper-free click reaction is described.

Bir Kullanarak Altın Nanopartiküller Verimli Radyoaktif bir Optimize Protokolü<sup&gt; 125</sup&gt; I-etiketli Azid Protez Grubu

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125I-labeled azide prosthetic group and its application to the efficient ...

Harnessing the Bioorthogonal Inverse Electron Demand Diels-Alder Cycloaddition for Pretargeted PET Imaging

Due to their exquisite affinity and specificity, antibodies have become extremely promising vectors for the delivery of radioisotopes to cancer cells for PET imaging. However, the necessity of labeling antibodies with radionuclides with long physical half-lives often results in high background radiation dose rates to non-target tissues. In order to circumvent this issue, we have employed a pretargeted PET imaging strategy based on the inverse electron demand Diels-Alder cycloaddition reaction. The methodology decouples the antibody from the radioactivity and thus exploits the positive characteristics of antibodies, while eschewing their pharmacokinetic drawbacks. The system is composed of four steps: (1) the injection of a mAb-trans-cyclooctene (TCO) conjugate; (2) a localization time period during which the antibody accumulates in the tumor and clears from the blood; (3) the injection of the radiolabeled tetrazine; and (4) the in vivo click ligation of the components followed by the clearance of excess radioligand. In the example presented in the work at hand, a 64Cu-NOTA-labeled tetrazine radioligand and a trans-cyclooctene-conjugated humanized antibody (huA33) were successfully used to delineate SW1222 colorectal cancer tumors with high tumor-to-background contrast. Further, the pretargeting methodology produces high quality images at only a fraction of the radiation dose to non-target tissue created by radioimmunoconjugates directly labeled with 64Cu or 89Zr. Ultimately, the modularity of this protocol is one of its greatest assets, as the trans-cyclooctene moiety can be appended to any non-internalizing antibody, and the tetrazine can be attached to a wide variety of radioisotopes.

The bioorthogonal inverse electron demand Diels-Alder cycloaddition has been harnessed to create an effective and modular pretargeted PET imaging strategy for cancer. In this protocol, the steps of this methodology are described in the context of a model system employing the colorectal cancer targeted antibody huA33 and a 64Cu-labeled radioligand.

Pretargeted PET Görüntüleme Bioorthogonal Ters Elektron Talep Diels-Alder Katılma Harnessing

Due to their exquisite affinity and specificity, antibodies have become extremely promising vectors for the delivery of radioisotopes to cancer cells for ...

Biyomühendislik

MR Molecular Imaging of Prostate Cancer with a Small Molecular CLT1 Peptide Targeted Contrast Agent

Tumor extracellular matrix has abundance of cancer related proteins that can be used as biomarkers for cancer molecular imaging. In this work, we demonstrated effective MR cancer molecular imaging with a small molecular peptide targeted Gd-DOTA monoamide complex as a targeted MRI contrast agent specific to clotted plasma proteins in tumor stroma. We performed the experiment of evaluating the effectiveness of the agent for non-invasive detection of prostate tumor with MRI in a mouse orthotopic PC-3 prostate cancer model. The targeted contrast agent was effective to produce significant tumor contrast enhancement at a low dose of 0.03 mmol Gd/kg. The peptide targeted MRI contrast agent is promising for MR molecular imaging of prostate tumor.

To demonstrate MR cancer molecular imaging with a small peptide targeted MRI contrast agent specific to clotted plasma proteins in tumor stroma in a mouse prostate cancer model.

Küçük Moleküler CLT1 Peptide Hedefli Kontrast Agent ile Prostat Kanseri MR Moleküler Görüntüleme

Tumor extracellular  matrix has abundance of cancer related proteins that can be used as biomarkers  for cancer molecular imaging. In this work,  we ...

Tıp

Pretargeted Radioimmunotherapy Based on the Inverse Electron Demand Diels-Alder Reaction

While radioimmunotherapy (RIT) is a promising approach for the treatment of cancer, the long pharmacokinetic half-life of radiolabeled antibodies can result in high radiation doses to healthy tissues. Perhaps not surprisingly, several different strategies have been developed to circumvent this troubling limitation. One of the most promising of these approaches is pretargeted radioimmunotherapy (PRIT). PRIT is predicated on decoupling the radionuclide from the immunoglobulin, injecting them separately, and then allowing them to combine in vivo at the target tissue. This approach harnesses the exceptional tumor-targeting properties of antibodies while skirting their pharmacokinetic drawbacks, thereby lowering radiation doses to non-target tissues and facilitating the use of radionuclides with half-lives that are considered too short for use in traditional radioimmunoconjugates. Over the last five years, our laboratory and others have developed an approach to in vivo pretargeting based on the inverse electron-demand Diels-Alder (IEDDA) reaction between trans-cyclooctene (TCO) and tetrazine (Tz). This strategy has been successfully applied to pretargeted positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging with a variety of antibody-antigen systems. In a pair of recent publications, we have demonstrated the efficacy of IEDDA-based PRIT in murine models of pancreatic ductal adenocarcinoma and colorectal carcinoma. In this protocol, we describe protocols for PRIT using a 177Lu-DOTA-labeled tetrazine radioligand ([177Lu]Lu-DOTA-PEG7-Tz) and a TCO-modified variant of the colorectal cancer targeting huA33 antibody (huA33-TCO). More specifically, we will describe the construction of huA33-TCO, the synthesis and radiolabeling of [177Lu]Lu-DOTA-PEG7-Tz, and the performance of in vivo biodistribution and longitudinal therapy studies in murine models of colorectal carcinoma.

This protocol describes the synthesis and characterization of a trans-cyclooctene (TCO)-modified antibody and a 177Lu-labeled tetrazine (Tz) radioligand for pretargeted radioimmunotherapy (PRIT). In addition, it details the use of these two constructs for in vivo biodistribution and longitudinal therapy studies in a murine model of colorectal cancer.

Pretargeted Radioimmunotherapy ters elektron talep Diels-Alder reaksiyonu üzerinde dayalı

While radioimmunotherapy (RIT) is a promising approach for the treatment of cancer, the long pharmacokinetic half-life of radiolabeled antibodies can ...

Synthesis and Bioconjugation of Thiol-Reactive Reagents for the Creation of Site-Selectively Modified Immunoconjugates

Maleimide-bearing bifunctional probes have been employed for decades for the site-selective modification of thiols in biomolecules, especially antibodies. Yet maleimide-based conjugates display limited stability in vivo because the succinimidyl thioether linkage can undergo a retro-Michael reaction. This, of course, can lead to the release of the radioactive payload or its exchange with thiol-bearing biomolecules in circulation. Both of these processes can produce elevated activity concentrations in healthy organs as well as decreased activity concentrations in target tissues, resulting in reduced imaging contrast and lower therapeutic ratios. In 2018, we reported the creation of a modular, stable, and easily accessible phenyloxadiazolyl methyl sulfone reagent &#8212; dubbed &#8216;PODS&#8217; &#8212; as a platform for thiol-based bioconjugations. We have clearly demonstrated that PODS-based site-selective bioconjugations reproducibly and robustly create homogenous, well-defined, highly immunoreactive, and highly stable radioimmunoconjugates. Furthermore, preclinical experiments in murine models of colorectal cancer have shown that these site-selectively labeled radioimmunoconjugates exhibit far superior in vivo performance compared to radiolabeled antibodies synthesized via maleimide-based conjugations. In this protocol, we will describe the four-step synthesis of PODS, the creation of a bifunctional PODS-bearing variant of the ubiquitous chelator DOTA (PODS-DOTA), and the conjugation of PODS-DOTA to the HER2-targeting antibody trastuzumab.

In this protocol, we will describe the synthesis of PODS, a phenyoxadiazolyl methyl sulfone-based reagent for the site-selective attachment of cargos to the thiols of biomolecules, particularly antibodies. In addition, we will describe the synthesis and characterization of a PODS-bearing bifunctional chelator and its conjugation to a model antibody.

Sentez ve Site seçici olarak oluşturulması için Thiol reaktif reaktif Bioconjugation Immunoconjugates modifiye

Maleimide-bearing bifunctional probes have been employed for decades for the site-selective modification of thiols in biomolecules, especially antibodies. ...

Positron Emission Tomography Imaging of Cell Trafficking: A Method of Cell Radiolabeling

Stem cell and chimeric antigen receptor (CAR) T-cell therapies are emerging as promising therapeutics for organ regeneration and as immunotherapy for various cancers. Despite significant progress having been made in these areas, there is still more to be learned to better understand the pharmacokinetics and pharmacodynamics of the administered therapeutic cells in the living system. For noninvasive, in vivo tracking of cells with positron emission tomography (PET), a novel [89Zr]Zr-p-isothiocyanatobenzyl-desferrioxamine ([89Zr]Zr-DBN)-mediated cell radiolabeling method has been developed utilizing 89Zr (t1/2 78.4 h). The present protocol describes a [89Zr]Zr-DBN-mediated, ready-to-use, radiolabeling synthon for direct radiolabeling of variety of cells, including mesenchymal stem cells, lineage-guided cardiopoietic stem cells, liver regenerating hepatocytes, white blood cells, melanoma cells, and dendritic cells. The developed methodology enables noninvasive PET imaging of cell trafficking for up to 7 days post-administration without affecting the nature or the function of the radiolabeled cells. Additionally, this protocol describes a stepwise method for the radiosynthesis of [89Zr]Zr-DBN, biocompatible formulation of [89Zr]Zr-DBN, preparation of cells for radiolabeling, and finally the radiolabeling of cells with [89Zr]Zr-DBN, including all the intricate details needed for the successful radiolabeling of cells.

Presented here is a protocol to radiolabel cells with a positron emission tomography (PET) radioisotope, 89Zr (t1/2 78.4 h), using a ready-to-use radiolabeling synthon, [89Zr]Zr-p-isothiocyanatobenzyl-desferrioxamine ([89Zr]Zr-DBN). Radiolabeling cells with [89Zr]Zr-DBN allows noninvasive tracking and imaging of administered radiolabeled cells in the body with PET for up to 7 days post-administration.

Hücre Kaçakçılığının Pozitron Emisyon Tomografisi Görüntülemesi: Bir Hücre Radyo-Etiketleme Yöntemi

Stem cell and chimeric antigen receptor (CAR) T-cell therapies are emerging as promising therapeutics for organ regeneration and as immunotherapy for ...

Kanser Araştırmaları

Initial Evaluation of Antibody-conjugates Modified with Viral-derived Peptides for Increasing Cellular Accumulation and Improving Tumor Targeting

Antibody-conjugates (ACs) modified with virus-derived peptides are a potentially powerful class of tumor cell delivery agents for molecular payloads used in cancer treatment and imaging due to increased cellular accumulation over current ACs. During early AC in vitro development, fluorescence techniques and radioimmunoassays are sufficient for determining intracellular localization, accumulation efficiency, and target cell specificity. Currently, there is no consensus on standardized methods for preparing cells for evaluating AC intracellular accumulation and localization. The initial testing of ACs modified with virus-derived peptides is critical especially if several candidates have been constructed. Determining intracellular accumulation by fluorescence can be affected by background signal from ACs at the cell surface and complicate the interpretation of accumulation. For radioimmunoassays, typically treated cells are fractionated and the radioactivity in different cell compartments measured. However, cell lysis varies from cell to cell and often nuclear and cytoplasmic compartments are not adequately isolated. This can produce misleading data on payload delivery properties. The intravenous injection of radiolabeled virus-derived peptide-modified ACs in tumor bearing mice followed by radionuclide imaging is a powerful method for determining tumor targeting and payload delivery properties at the in vivo phase of development. However, this is a relatively recent advancement and few groups have evaluated virus-derived peptide-modified ACs in this manner. We describe the processing of treated cells to more accurately evaluate virus-derived peptide-modified AC accumulation when using confocal microscopy and radioimmunoassays. Specifically, a method for trypsinizing cells to remove cell surface bound ACs. We also provide a method for improving cellular fractionation. Lastly, this protocol provides an in vivo method using positron emission tomography (PET) for evaluating initial tumor targeting properties in tumor-bearing mice. We use the radioisotope 64Cu (t1/2 = 12.7 h) as an example payload in this protocol.

Viral-derived peptides coupled to antibody-conjugates (ACs) is an approach gaining momentum due to the potential of delivering molecular payloads with increased tumor cell accumulation. Utilizing common methods to evaluate peptide conjugation, AC and payload intracellular accumulation, and tumor targeting, this protocol helps researchers during the key initial development phases.

Antikor conjugates ilk değerlendirilmesi ile Viral kaynaklı peptidler hücresel birikimi artan ve tümör hedefleme artırmak için değiştirilmiş

Antibody-conjugates (ACs) modified with virus-derived peptides are a potentially powerful class of tumor cell delivery agents for molecular payloads used ...

Murine Lymphocyte Labeling by 64Cu-Antibody Receptor Targeting for In Vivo Cell Trafficking by PET/CT

This protocol illustrates the production of 64Cu and the chelator conjugation/radiolabeling of a monoclonal antibody (mAb) followed by murine lymphocyte cell culture and 64Cu-antibody receptor targeting of the cells. In vitro evaluation of the radiolabel and non-invasive in vivo cell tracking in an animal model of an airway delayed-type hypersensitivity reaction (DTHR) by PET/CT are described.
In detail, the conjugation of a mAb with the chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) is shown. Following the production of radioactive 64Cu, radiolabeling of the DOTA-conjugated mAb is described. Next, the expansion of chicken ovalbumin (cOVA)-specific CD4+ interferon (IFN)-&#947;-producing T helper cells (cOVA-TH1) and the subsequent radiolabeling of the cOVA-TH1 cells are depicted. Various in vitro techniques are presented to evaluate the effects of 64Cu-radiolabeling on the cells, such as the determination of cell viability by trypan blue exclusion, the staining for apoptosis with Annexin V for flow cytometry, and the assessment of functionality by IFN-&#947; enzyme-linked immunosorbent assay (ELISA). Furthermore, the determination of the radioactive uptake into the cells and the labeling stability are described in detail. This protocol further describes how to perform cell tracking studies in an animal model for an airway DTHR and, therefore, the induction of cOVA-induced acute airway DHTR in BALB/c mice is included. Finally, a robust PET/CT workflow including image acquisition, reconstruction, and analysis is presented.
The 64Cu-antibody receptor targeting approach with subsequent receptor internalization provides high specificity and stability, reduced cellular toxicity, and low efflux rates compared to common PET-tracers for cell labeling, e.g.64Cu-pyruvaldehyde bis(N4-methylthiosemicarbazone) (64Cu-PTSM). Finally, our approach enables non-invasive in vivo cell tracking by PET/CT with an optimal signal-to-background ratio for 48 h. This experimental approach can be transferred to different animal models and cell types with membrane-bound receptors that are internalized.

Murine Lymphocyte Labeling by 64Cu-Antibody Receptor Targeting for In Vivo  Cell Trafficking by PET/CT

Following the preparation of a 64Cu-modified monoclonal antibody binding to a transgenic murine T cell receptor, T cells are radiolabeled in vivo, analyzed for viability, functionality, labeling stability and apoptosis, and adoptively transferred into mice with an airway delayed-type hypersensitivity reaction for non-invasive imaging by positron emission tomography/computed tomography (PET/CT).

tarafından Kemirgen Lenfosit Etiketleme<sup&gt; 64</sup&gt; Cu-Antikor Reseptör için hedefleme<em&gt; In Vivo</em&gt; PET / CT ile hücre Trafik

This protocol illustrates the production of 64Cu and the chelator conjugation/radiolabeling of a monoclonal antibody (mAb) followed by murine lymphocyte ...

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