Association of tumor-informed minimal residual disease (MRD) with clinical outcomes for muscle invasive bladder cancer (MIBC): A multicenter retrospective real-world analysis.
Authors: Kommalapati Ajitha , Laliotis George , Glover Michael , Selig Grayce , Kollipara Revathi , Mahmood Tamara , Shah Sumit , Hoimes Christopher J. , Stewart Tyler F. , Sharma Shruti , Malhotra Meenakshi , Pajak Natalia , Calhoun Mark , ElNaggar Adam , Liu Minetta C. , Basu Arnab , Galsky Matt D. , Tan Alan 
Published: June 2023

3050 Background: Muscle invasive bladder cancer is associated with a significant elevated risk of mortality and morbidity due to micro metastatic spread at the time of diagnosis. Accurate biomarkers to guide treatment determination and evaluate response are needed. Previous studies using tumor informed ct-DNA have shown that MRD assessment may be informative in these scenarios. Methods: We conducted a retrospective multicenter analysis of real-world data obtained from commercial testing (Signatera; Natera, Inc.). This cohort of MIBC patients included those who underwent radical cystectomy with a minimum follow up of 90 days. Data were collected on patient demographics, clinical and pathological staging, histologic type, and treatments. Correlation of ct-DNA status with clinical outcomes was analyzed using Cox-regression analysis to evaluate utility of the assay for detecting residual disease post-surgery and radiological recurrence. Results: A total of 109 patients with 545 plasma samples were identified that fit the inclusion criteria. The majority of the patients [79, 72.5%] were male, with a median age of 70 (range: 32-88) years. Most patients had pure urothelial carcinoma [73.4%, 80/109]. Median follow-up was 13.63 (range: 3-89.04) months. On analyzing the first time point post-surgery (median 54 days), 91.55% (65/71) of ct-DNA negative patients at the first post-surgical test remained recurrence free while 65.79% (25/38) of positive patients had recurred at data cut-off. Therefore, ct-DNA positivity at the first post-surgical timepoint was associated with shorter disease-free survival (DFS) (HR=9.9, 95%CI: 4.1-24%, p<0.001). ct-DNA detected imaging recurrence with a median lead time of 61 days (range: 12-381). Similarly, on analyzing ct-DNA positivity at any time post-surgery, of those who remained ct-DNA negative (N=63), 96.83% (61/63) showed no evidence of recurrent disease. On the other hand, 63.04% (29/46) of pts with ct-DNA positivity at any time after cystectomy recurred and experienced reduced DFS (HR=25, 95%CI: 5.9-103%, p<0.001). The assay’s sensitivity for predicting radiological recurrence at any time post-surgery was 93.55%. Notably, in the multivariate analysis, anytime ct-DNA positivity after cystectomy was found to be the only significant risk factor associated with shorter DFS (HR=23.07, 95%CI: 5.1-104.4, p<0.001). Conclusions: In this initial analysis of real-world data, MRD detection via tumor-informed ct-DNA testing was highly prognostic of patient outcomes post-surgery and may guide adjuvant treatment decisions. Future studies in this setting will explore the utility of ct-DNA testing as a predictive biomarker in response to systemic therapy.