Indium-111–labeled Girentuximab ImmunoSPECT as a Diagnostic Tool in Clear Cell Renal Cell Carcinoma

Abstract Background Improved and more frequent radiologic evaluation has resulted in increased identification of renal masses of unknown origin, which frequently pose a diagnostic dilemma for urologists. Objective Carbonic anhydrase IX (CAIX) is an antigen ubiquitously expressed in clear cell renal cell carcinoma (ccRCC). The specific and high level of expression in ccRCC makes CAIX an excellent target for imaging ccRCC lesions. We present our experience with immuno–single-photon emission computed tomography (immunoSPECT) imaging with the indium-111 (111 In)–labeled anti-CAIX antibody girentuximab in patients presenting with either a primary renal tumor or a history of ccRCC and lesions suspect for metastases during follow-up. Design, setting, and participants Twenty-nine patients received 100–200 MBq111 In-labeled girentuximab. Whole-body and single photon emission computed tomography (SPECT) images were acquired after 4–7 d. Intervention Injection with111 In-girentuximab and image acquisition after 4–7 d. Outcome measurements and statistical analysis Accuracy of111 In-girentuximab immunoSPECT. Results and limitations Distinct uptake of111 In-girentuximab was seen in 16 of 22 patients presenting with a renal mass. All renal masses proven to be ccRCC after resection ( n = 15) were detected with111 In-girentuximab. Suspect lesions of six patients showed no uptake of111 In-girentuximab. In these patients, ccRCC was not found, nor progression occurred. Seven patients with a history of ccRCC and possible metastatic lesions on follow-up computed tomography scans were imaged with111 In-girentuximab. In four of these patients, the lesions showed preferential uptake of111 In-girentuximab and local or systemic treatment was initiated. In three other cases, no111 In-girentuximab targeting was seen. During follow-up of these three patients, one showed progression, for which systemic treatment was started. In the two other patients, no progression occurred, suggesting a benign nature. Conclusions111 In-girentuximab immunoSPECT can be used to detect ccRCC lesions in patients with a primary renal mass and to clarify the nature of lesions suspect for metastases in patients with a history of ccRCC.