BLUE RIBBON POSTER RADIOPHARMACEUTICALS: Renal Dosimetry and Creatinine Clearance Trends In Lu-177-PSMA Therapy: A Single-Institution Analysis
Abstract
Purpose
Despite the widespread use of Lu-177-PSMA for treatment of prostate cancer, the association between renal dose and toxicity remains unclear. This study investigates this relationship.
Methods
SPECT/CT based dosimetry was performed using images obtained at 4-, 24-, 48-, and 72- hours after therapeutic administration of Lu-177-PSMA for 17 patients at our institution. Cumulative renal dose was estimated by multiplying single-cycle dose (Gy/GBq) by the total administered activity across treatment cycles. The Cockcroft-Gault formula was used to estimate creatinine clearance from serum creatinine. The average follow-up time between the initial and final serum creatinine measurement was 765.5 (SD = 234.1) days for patients who had prior PSMA therapy (n = 8) and 224.4 (SD = 101.2) days for patients who had not (n = 9). Percent change in creatinine clearance from baseline to final follow-up was plotted against total renal dose, and the relationship was assessed using Spearman’s rank correlation. Longitudinal changes in renal function were evaluated by plotting the absolute and relative changes in creatinine clearance as a function of cumulative absorbed dose.
Results
A strong negative relationship was observed between total renal dose and percent change in creatinine clearance from baseline to final follow-up (rs(15) = -0.65, p < 0.01). Longitudinal plots of absolute and percent changes in creatinine clearance versus cumulative dose demonstrated a visual decreasing trend, which merits further investigation.
Conclusion
These results suggest an important association between the decline in creatinine clearance and total renal dose. However, as radiation-induced renal damage can exhibit a long latency period, longer-term follow-up with a larger cohort of patients is warranted.