Department of Chemistry, Lomonosov Moscow State University, GSP-1, Leninskie Gory, Moscow, 119991, Russia.
The Center of Isotopes (CENTIS), Ave. Monumental y Carretera La Rada, Km 3 1/2, CP 32700, San Jose de las Lajas, Mayabeque, Republic of Cuba.
Curr Radiopharm. 2023 Jun 5;16(3):233-242. doi: 10.2174/1874471016666230221102518.
The feasibility of preparing the "in-house" generators and the Th- DTPA(DOTA)-Nimotuzumab radioimmunoconjugate was evaluated. Th is perspective for TAT, however, due to short half-life it is preferable to apply this radionuclide for readily available epithelial malignancies. Nimotuzumab being specific for EGFR expressing cells as a targeting moiety is considered to be suitable for thorium delivery.
TEVA extraction chromatographic resin and anion exchange resin AG 1x8 were used as sorbents for Th generator. In order to determine features of labeling by Th4 we applied Th as a longer-lived analog of short-lived Th and the immunoconjugates DTPA(DOTA)-Nimotuzumab were used for radiolabeling.
The generator on the base of TEVA resin has shown higher volume activity of the product compared to the AG 1x8. The Th volume concentration was up to 80%/mL. The radiolabeling of BFCA by thorium radioisotopes reached 95% at the MR(Th:p-SCN-Bn-DTPA) = 1:100 and 86% for MR(Th:p-SCN-Bn-DOTA) = 1:5000 at 90°C. The procedure of Nimotuzumab labeling with Th4+ for radiotherapy of EGFR-overexpressing carcinomas was established. The overall labeling yield in both radioimmunoconjugates - DTPA and DOTA functionalized - was in the range of 45-50%. The immunoconjugate Nimotuzumab-p-SCN-Bn-DTPA was obtained with a molar ratio 1:25 (Nimotuzumab: BFCA), within 1 hour of conjugation at 25°C and labelled postconjugation approach. Whereas Nimotuzumab-p-SCN-Bn-DOTA was obtained at the same conditions, but radiolabeled by the method of pre-conjugation.
Thorium-234 incorporation into both radioimmunoconjugates reached 45-50%. It has been shown that Th-DTPA-Nimotuzumab radioimmunoconjugate specifically bound with EGFR overexpressing epidermoid carcinoma A431 cells.
评估了制备“内部”发生器和 Th-DTPA（DOTA）-尼莫单抗放射性免疫偶联物的可行性。然而，由于半衰期短，对于 TAT 而言，最好将这种放射性核素应用于现成的上皮恶性肿瘤。尼莫单抗作为针对表达 EGFR 细胞的靶向部分，被认为适合钍的输送。
TEVA 萃取色谱树脂和阴离子交换树脂 AG 1x8 被用作 Th 发生器的吸附剂。为了确定 Th4 标记的特点，我们应用 Th 作为短寿命 Th 的长寿命类似物，并用 DTPA（DOTA）-尼莫单抗免疫缀合物进行放射性标记。
基于 TEVA 树脂的发生器显示出比 AG 1x8 更高的产物体积活度。Th 体积浓度高达 80%/mL。在 90°C 下，MR(Th：p-SCN-Bn-DTPA)=1:100 时，钍放射性同位素对 BFCA 的放射性标记达到 95%，MR(Th：p-SCN-Bn-DOTA)=1:5000 时达到 86%。建立了用 Th4+对 EGFR 过表达癌进行放射治疗的尼莫单抗标记方法。两种放射性免疫偶联物（DTPA 和 DOTA 功能化）的总标记产率均在 45-50%范围内。用摩尔比 1:25（尼莫单抗：BFCA）在 25°C 下 1 小时内进行偶联，并在偶联后进行标记，得到尼莫单抗-p-SCN-Bn-DTPA 免疫偶联物。而在相同条件下，用预偶联法得到尼莫单抗-p-SCN-Bn-DOTA 免疫偶联物。
两种放射性免疫偶联物中钍-234 的掺入率达到 45-50%。已经表明，Th-DTPA-尼莫单抗放射性免疫偶联物特异性结合表达 EGFR 的表皮样癌细胞 A431。
