Purpose: Detection of residual or recurrent vital renal tumor on follow-up (FU) cross-sectional imaging after ablative therapy is challenging. The specific and high expression levels of carbonic anhydrase IX (CAIX) in clear cell renal cell carcinoma (ccRCC) makes it a suitable target for imaging using radiolabeled anti-CAIX antibody girentuximab. The objective of this study was to evaluate the feasibility of targeted FU imaging 1 month after cryoablation of ccRCC using single photon emission computed tomography (SPECT) after 111In-labeled girentuximab administration.
Methods: In this prospective study 16 patients underwent 111In-girentuximab-SPECT before MR-guided renal cryoablation between February 2015 and September 2018. In case of tumor targeting 111In-girentuximab-SPECT was repeated 1 month following MR-guided cryoablation. Presence of residual or recurrent vital tumor was assessed on contrast-enhanced cross-sectional imaging during further FU. The standard FU imaging protocol consisted of MRI/CT scans at 1, 3, 6, 12, and 18 months and annually thereafter.
Results: A total of 10 (63%) patients showed positive tumor targeting on 111In-girentuximab-SPECT before cryoablation and 9 ( 56%) were eligible to undergo FU SPECT. Of the 9 111In-girentuximab-SPECT FU scans, 8 (89%) were considered negative. One (11%) scan showed uptake suggestive for residual vital tumor. Six months after treatment, FU CT showed contrast enhancement suggestive for residual/recurrent disease in the ablated zone at the site of the 111In-girentuximab uptake after treatment. During a mean FU of 21 months (range 1-33) no other cases with residual/recurrent disease were detected.
Conclusion: FU imaging with 111In-girentuximab-SPECT is feasible after ccRCC cryoablation and may contribute to early detection of residual or recurrent disease.
Keywords: CAIX; Cryoablation; Follow-up; Renal cell carcinoma; Single photon emission computed tomography.