Introduction:

Bladder cancer (BC) is a common urinary tract cancer with a variable clinical course. With frequent recurrence, cystoscopy and urine cytology are routinely employed during follow-up of patients with a history of non-muscle invasive bladder cancer (NMIBC). Although there are multiple FDA approved urine-based tests for BC detection and surveillance, diagnostic accuracy of these urine-based assays is still suboptimal, especially in the surveillance setting. Here, we explore the feasibility of a newly developed urine-based DNA methylation test for detection of recurrence in NMIBC. 

Methods:

We included patients undergoing blue-light surveillance cystoscopy for NMIBC between July 2019 and August 2022. Patient were required to have a prior diagnosis of urothelial carcinoma. Urine samples were collected at each surveillance cystoscopy as well as before and after transurethral resection of bladder tumor (TURBT). Samples were analyzed with Bladder CARE, a urine-based assay that measures methylation levels of 3 bladder cancer specific biomarkers (TRNA-Cys, SIM2, and NKX1-1) and two internal control loci using methylation-sensitive restriction enzymes coupled with qPCR. Results are reported as Bladder CARE Index (BCI) score and categorized as “positive” (BCI>5), “high risk” (2.5<BCI£5) or “negative” (BCI£2.5). Association between changes in BCI score and category, recurrence and pathology findings were assessed.

Results:

101 patients (median age 74, 86% male) were included. 24(24%) patients had recurrence. Bladder CARE detected the cancer recurrence on an average of 7.35 months prior to cystoscopy. Recurrence in 1 case(#23) was detected at the same time as cystoscopy and 1 case(#11) was missed by Bladder CARE(Fig.1). BCI values for detection of recurrence demonstrated the sensitivity, specificity, positive predictive values(PPV), and negative predictive value(NPV) of 92.5%, 71.5%, 86% and 83%, respectively(Fig.2). Bladder CARE showed sensitivity of 95% for high grade disease, 89% for CIS and 100% for T1(Fig.3).

15/56 patients who received intravesical BCG or chemotherapy during the study period, experienced recurrence, of whom 11/15 (73%) had persistent elevated BCIs during the course of the study. Patients with a positive BCI within the two months following the TURBT had significantly lower recurrence free survival at 2 years(P= 0.001,Fig.4).

Conclusion:

Our preliminary findings suggest a potential utility for this urine-based methylation test in early detection of recurrence in NMIBC. Also, this study confirms the low sensitivity and NPV for urine cytology. Bladder CARE has high sensitivity and can potentially predict future recurrences. Larger sample size with longer follow-up is required to validate these results.

Funding: Zymo Research Corp, Pangea Laboratory