A standardised attenuated dosing of 177 lutetium-prostate-specific membrane antigen therapy for patients with metastatic castration-resistant prostate carcinoma and preexisting renal impairment.

OBJECTIVE

This study analysed the safety and effectiveness of a 20% dose reduction of 177 Lutetium-labelled prostate-specific membrane antigen (PSMA) radioligand therapy in patients with metastatic castration-resistant prostate carcinoma (mCRPC) and preexisting impaired renal function.

METHODS

In this retrospective study, 16 mCRPC patients with impaired renal function - estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m 2 who received 177 Lu-PSMA-I&T were identified. Median number of cycles was 4 (range 1-8 cycles), and median interval between cycles was 6 weeks. Renal function was monitored throughout the treatment. Therapy response was assessed via prostate-specific antigen (PSA) measurements. Patients received a 20% dose reduction from the standard dose of 7.4 GBq. Mean follow-up time was 8.5 months (range 2-37 months). Kaplan-Meier analysis was performed to obtain progression-free survival (PFS) and overall survival (OS).

RESULTS

Mean baseline eGFR was 48 ml/min/1.73 m 2 (range 21-59 ml/min/1.73 m 2 ). Mean end-of-treatment eGFR was 51 ml/min/1.73 m 2 (range 19-83 ml/min/1.73 m 2 ). At the end of follow-up, the mean eGFR was 48 ml/min/1.73 m 2 (range 20-83 ml/min/1.73 m 2 ). There was no evidence that eGFR was affected by the 177 Lu-PSMA-I&T treatment either after the last cycle or at the end of follow-up ( P  > 0.05). No patients suffered grade 4 renal toxicity. After 1 cycle, 50% of patients had a partial PSA response, which increased to 73% after two cycles. Median PFS was 12 months [95% confidence interval (CI): 4-14 months], and OS was 17 months (95% CI: 13-40 months).

CONCLUSION

Findings support the feasibility of 177 Lu-PSMA-I&T treatment in mCRPC patients with preexisting renal impairment (eGFR 21-59 ml/min/1.73 m 2 ) when a 20% dose reduction is applied.