Radioimmunodetection of recurrence of colorectal cancer using monoclonal antibody

使用肿瘤相关抗原的放射性标记单抗(MAb)进行成像是一种潜在的定性诊断的特异性方法。用纯化的CEA免疫制备抗CEA的MAbCEA102，并用于结直肠癌的放射性示踪剂。为了研究放射性标记CEA102的特异性蓄积，用富士计算机放射自显影(FCR)进行了放射自显影研究，发现131I标记CEA102在原发肿瘤甚至小的肝转移瘤中有明显的定位。然后，我们将131-I标记的CEA102应用于20例肝转移、局部复发和/或原发肿瘤的患者。总敏感度为71.4%，无假阳性。由于~(131)I有能量的伽马射线发射，且在膀胱内有较高的游离~(131)I蓄积量，我们尝试使用半衰期较短的~(111)In作为示踪剂，可用于单光子发射断层扫描(SPECT)。我们应用111In标记的CEA102对10例患者(原发肿瘤1例，回肠CEA产生肿瘤1例，直肠癌局部复发8例)进行了检测。总体敏感度为70%。虽然由于111-In在肝脏中的高蓄积，该示踪剂不适合检测肝脏转移，但发射CT在诊断直肠癌局部复发方面特别有用。上述结果表明，放射成像在定性诊断方面有很大潜力。

Imaging using radiolabeled monoclonal antibody (MAb) to tumor-associated antigen is potentially specific approach to qualitative diagnosis. The MAbCEA102 against CEA was produced by immunization with purified CEA,and used as a radiotracer for the imaging of colorectal cancer. To investgate the specific accumulation of radiolabeled CEA102, autoradiographic study using Fuji Computed Radiography (FCR) was performed, and predominant localizations of 131-I-labeled-CEA102 were observed in primary tumors and even small liver metastases. We then applied 131-I-labeled-CEA102 to 20 cases with liver metastases, local recurrences, and/or primary tumors. Overall sensitivity was 71.4%, and no false positive was observed. Since 131-I has energic gamma-ray emission, and high accumulation of free 131-I in bladder, we attempted using 111-In as a radiotracer which has a short half life and provides to use Single Photon Emission CT (SPECT) . We applied to 10 cases (primary tumor 1, CEA producing tumor of ileum 1, and local recurrence of rectal cancer 8) using 111-In-labeled CEA102. Overall sensitivity was 70%. Although this radiotracer was not suitable to detect liver metastasis due to high accumulation of 111-In in liver, it was especially useful to diagnose local recurrence of rectal cancer using Emission CT.The above results demonstrated that radioimaging has a great potential in qualitative diagnosis.