Background: [177Lu]Lu-PSMA-617 is a well-tolerated therapy for the treatment of metastatic prostate cancer. However, because of the mainly renal excretion of the tracer, the kidneys are one of the most limiting organs. The purpose of this study was to examine the post-therapeutic changes in renal function over time and to identify risk factors for developing renal toxicity. We also tested the reliability of markers for renal function monitoring.
Methods: Fifty-five patients with castrate-resistant metastatic prostate cancer treated with at least three cycles of [177Lu]Lu-PSMA-617 were investigated. Renal function was assessed through laboratory tests (creatinine, GFR, cystatin C) and Tc-99 m-MAG3 measurements. Adverse events were classified according to the Common Terminology Criteria for Adverse Events (CTCAE) v4.0. To identify risk factors for renal toxicity, we used Pearson's correlation coefficient and the corresponding p values.
Results: None of the 55 patients experienced severe nephrotoxicity (grade 3/4). In 14 patients (25%), we observed increased creatinine levels of CTC 1° or 2°. There were 16 cases of increased GFR (grade 1/2). At the baseline, only 14 patients had elevated cystatin C. However, post-therapeutic cystatin C was elevated in 32 patients (58%). A significant effect on renal function was found for age (p = 0.049), hypertension (p = 0.001) and pre-existing kidney disease (p = 0.001). The most reliable predictive markers of nephrotoxicity were TER-MAG3 and cystatin C.
Conclusion: Renal toxicity in patients treated with [177Lu]Lu-PSMA-617 was low. There was no (sub)acute grade 3 or 4 nephrotoxicity.
Keywords: 177Lu; Nephrotoxicity; PSMA; Prostate cancer; Radioligand therapy; Renal function.