Introduction:

Recently, Mitomycin C (MMC) hydrogel was FDA approved for the intra-pelvicalyceal treatment of low grade upper tract urothelial carcinoma (UTUC). However, there remains a cohort of patients with recurrent high grade UTUC in functionally solitary kidneys where a nephroureterectomy would render them anephric. In highly selected patients who wish to avoid dialysis or who are poor surgical candidates, we have used repetitive intra-pelvicalyceal treatment with MMC mixed with a contrast agent such as iopamidol, to aid in visualizing the MMC within the renal pelvicalyceal system. Use of contrast minimizes the likelihood of pyelovenous backflow decreasing the risk of systemic toxicity, and it enables the surgeon to visually confirm exposure of the tumor to the MMC solution. This study seeks to confirm efficacy of MMC when mixed with iopamidol contrast agent.

Methods:

Three human high grade urothelial carcinoma (UC) cell lines were cultured until logarithmic growth and then allowed to attach to 96-well microtiter plates for 24 hours. Cells were treated for 60 minutes at 37 °C with 100 ug/mL MMC diluted with saline or iopamidol at varying concentrations. Saline alone was used as a control. Then solution was aspirated and cells were washed and resuspended in drug-free growth medium and incubated for 24-72 hours. After 24 and 72 hours, a dimethyl thiazolyl tetrazolium (MTT) test was performed to qualitatively measure cell viability after treatment. The experiment was performed in triplicate for each group. For each cell line, one-way ANOVA was used to compare mean values between six treatment groups. Tukey’s multiple comparison test was used to control the overall type I error in post-hoc pairwise comparisons.

Results:

Both MMC and MMC mixed with iopamidol were effective in inducing cell death in all three cell lines, compared to the saline control. This cell death was evident after 24 hours and even more robust after 72 hours (p < 0.0001 for all comparisons). Figure 1 demonstrates the mean surviving fraction determined by the MTT assay of cell viability for each treatment group in all three cell lines.

Conclusion:

Instillation of MMC mixed with iopamidol is an effective method to treat high grade UTUC in vitro even at 1/10^th the concentration used in vivo. These findings are translatable to intra-pelvicalyceal treatments in highly selected patients.

Funding: University of Rochester Medical Center Department of Urology