Scintigraphic detection of xenografted renal tumor by anti-renal cancer monoclonal antibody radiolabeled with technetium-99m

Abstract

腎細胞癌の画像診断を目指して, 腎細胞癌に特異的に反応するモノクローナル抗体(RCS-1)の, 生体内での腫瘍への集積性の基礎的検討を行った.抗体はテクネシウム標識して検査に用いた.標識抗体の腫瘍への集積性は, 腎細胞癌(AM-RG-3, CCF-RC-2), 胃癌(NUGC-4)移植ヌードマウスを用いて検討した.標識抗体を腹腔に投与し, 48時間後に各組織への集積を検査した.腫瘍への集積性の指標となる腫瘍/血液で各腫瘍を比較するとそれぞれ1.05, 0.80, 0.55となり胃癌株に対して腎細胞癌株に有意に集積しており, 腎細胞癌特異的な反応として集積していることが確認できた.又, シンチグラム像としても本抗体の集積を確認することができた

Accumulation in the tumor of the RCS-1 monoclonal antibody, which recognizes the cell surface antigen of renal cancer cells was examined. The antibody purified by affinity chromatography (protein-A column) and gel fractionation was labeled with technetium-99m (99mTc) by a direct method. High labeling efficiency (> 98%) could be routinely obtained. However, the 99mTc labeling of the antibody did not reduce the reactivity of the RCS-1 antibody. The labeled antibody was injected into nude mice transplanted with human renal and gastric tumors, and the accumulation of the antibody in each tumor and various tissues was compared at 48 hours after injection. The highest accumulation of radiolabeled RCS-1 antibody was observed in the AM-RC-3 renal tumors; at 8.0% of the injected dose per gram and a tumor-to-blood ratio of 1.05, respectively. However, the radiolabeled RCS-1, did not show specific accumulation in the gastric tumor nor in any tissues tested. The xenografted tumor, AM-RC-3 was successfully visualized with the radiolabeled RCS-1 antibody by scintigraphy.