Late adverse events to iodinated contrast media in patients treated with IL-2: a safety report from the Danish Renal Carcinoma Group (DaRenCa) study – 1

Background A higher incidence of late adverse events (LAEs) to iodinated contrast media in interleukin-2 (IL-2)-treated patients has been reported. Purpose To assess the incidence of LAEs after administration of iodinated contrast media in patients with metastatic renal cell carcinoma (mRCC) treated with IL-2. Material and Methods Patients were randomized to treatment with IL-2 and interferon-α with/without bevacizumab in the Danish Renal Carcinoma Group study – 1. Patients underwent a computed tomography (CT) scan at baseline, at one month, at three months, and every third month until RECIST 1.1 defined progression. LAEs due to iodinated contrast media were systematically registered according to the Common Terminology Criteria for Adverse Events classification. Results In total, 89 patients were included and underwent a total of 507 contrast-enhanced CT scans. An overall incidence of 46 (9.1%) LAEs was observed in 38 of 89 (42.7%) patients; 3 LAEs at baseline (3.4% of all baseline scans), 39 (13.9%) LAEs during IL-2-based therapies, and 4 (2.9%) LAEs after termination of IL-based therapies. There was no difference in progression-free survival, overall survival, and treatment response in patients experiencing LAEs compared to patients without LAEs ( P = 0.2, P = 0.5, and P = 0.6, respectively). Conclusion Patients with mRCC demonstrated a higher incidence of LAEs after administration of iodinated contrast during ongoing IL-2 therapy, indicating that iodinated contrast media may cause a recall phenomenon of IL-2 toxicities in patients with mRCC. Treatment with IL-2 should not be a contraindication for contrast-enhanced scans in patients with mRCC but expertise and vigilance are required.