SUO 2018: Phase III Trial of Intravenous Mannitol vs. Placebo During Nephron Sparing Surgery: 3 Year Outcomes

Phoenix, Arizona ( In a prospective, randomized, placebo-controlled, double-blind trial it was demonstrated that patients with normal kidney function who received mannitol during nephron-sparing surgery did not manifest improved kidney function compared to patients who received placebo at 6 weeks and 6 months following surgery. Despite these findings, some have suggested that patients with comorbidities, including lower preoperative estimated glomerular filtration rate, may still derive some benefit. In this presented study, these patients were reexamined at the 3-year follow-up time point and their long-term renal function outcomes were assessed. 

Between 2012 and 2015, 199 participants with normal renal function (defined as preoperative estimated glomerular filtration rate (eGFR) >45 ml/min/1.73m2) who underwent partial nephrectomy at Memorial Sloan Kettering Cancer Center were randomized. They either received mannitol (12.5g) or placebo intravenously within 30 minutes prior to renal vascular clamping during surgery. In the initial study, the original follow-up was at 6 months following surgery with renal function assessment using differences in eGFR. In this study, all original patients were followed for 3 years and their renal function was assessed.

For this long-term follow-up, 134 (67%) of patients had GFR available at 3 years. The results demonstrated that the median age at the time of surgery was 57.8 months, 63% were male and 81% were Caucasian. The median follow-up was 3.8 years. At baseline, median preoperative eGFR was similar with 86 ml/min/1.73m2 (IQR: 71-99) in the mannitol arm and 89 ml/min/1.73m2 (IQR: 78-100) in the placebo arm. Following 3 years of follow-up, the mean eGFR was 77 ml/min/1.73m2 (20) in the mannitol arm and 79 ml/min/1.73m2 (16) in the placebo arm. Summarizing the results, at 6 months, and 3 years of follow-up, the differences in eGFR between both arms were not significant, as can be demonstrated in figure 1.

SUO 2018 poster 180 effect of mannitol
Figure 1. The effect of mannitol on post-operative eGFR (6 months and 3 years) stratified by patient or surgical factors

In this important study, after 3 years of follow-up, patients with normal kidney function who received 12.5g mannitol during partial nephrectomy did not demonstrate improved renal function compared to placebo across all time points. There is also no evidence of effect modification by comorbidities, including lower preoperative eGFR, supporting the validity of the original trial conclusions.

Presented by: Nathan C. Wong, Memorial Sloan Kettering Cancer Center, New York, New York

Written By: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer, @GoldbergHanan, at the 19th Annual Meeting of the Society of Urologic Oncology (SUO), November 28-30, 2018 – Phoenix, Arizona