<sup>177</sup>Lu-PSMA radioligand therapy of prostate cancer in patients with single functioning kidney — ASN Events
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  3. 177Lu-PSMA radioligand therapy of prostate cancer in patients with single functioning kidney

177Lu-PSMA radioligand therapy of prostate cancer in patients with single functioning kidney (#85)

Aviral Singh 1 , Chistiane Schuchardt 1 , Harshad Kulkarni 1 , Karin Niepsch 1 , Richard P. Baum 1
  1. Theranostics Center for Molecular Radiotherapy and Molecular Imaging, Zentralklinik Bad Berka, Bad Berka, Germany

Objective: 177Lu-PSMA radioligand therapy (PRLT) is a promising treatment option for patients with metastatic castration-resistant prostate cancer (mCRPC). High 177Lu-PSMA uptake in kidneys has been reported as a concern for nephrotoxicity. Therefore, we assessed the effects of 177Lu-PRLT in patients with mCRPC possessing a single functioning kidney.

Methods: 119 patients with mCRPC received 300 cycles of 177Lu-PRLT (mean administered radioactivity: 6 GBq). Two (1.68%) patients had a single functioning kidney. Pre-therapy and pre-scheduled post-therapy renal function test (RFT): urea, creatinine, eGFR, and MAG3-scintigraphy based tubular-extraction rate (TER) were performed. Comparative dosimetry was performed in a control group of 30 randomly selected patients with bilateral functional kidneys.

Results: Patient 1 (P1) received 3 cycles of 177Lu-PRLT with cumulative radioactivity of 20 GBq (mean 6.7 GBq/cycle) over 4 months. Baseline RFT: urea 7.3, creatinine 111.8, pre-therapy n-3: urea 6.3; creatinine 102.7. TER reduced by a clinically negligible factor of 5% (baseline 140 ml/min, before third PRLT 129 ml/min). Patient 2 (P2) received 4 cycles of 177Lu-PRLT with cumulative radioactivity of 23 GBq (mean 5.7 GBq/cycle) over 6 months. Baseline RFT: urea 11.9, creatinine 82.7, pre therapy n-4 85.4. TER reduced by 26% (baseline 199 ml/min, before fourth PRLT 132 ml/min). eGFR remained persistently >60 for both patients. Renal dosimetry for the control group revealed an effective half-life of 39 hours, mean absorbed dose of 1 mGy/MBq (mean 0.4-2.0 mGy/MBq), and mean absorbed dose of 6 Gy per treatment.

Conclusion: In this group of patients with a single functional kidney, no clinically significant acute nephrotoxicity was observed. Despite a reduction of TER in one patient assessed prior to the fourth treatment, the renal function tests remained unaffected. Dosimetry revealed favourable tracer kinetics. Long term follow-up of these patients is warranted, and more patients need to be studied to validate these findings.