The LOBSTER study (NCT05080998), an observational trial assessing the performance of the Cxbladder Monitor and Monitor Plus tests in the surveillance of urothelial carcinoma recurrence, is underway. The study focuses on patients with low-, intermediate-, and high-risk disease. Interim data, presented at the 100th annual meeting of the Western Section of the American Urological Association (WSAUA), highlights the potential of Cxbladder to reduce the burden of cystoscopy in these patients.
Study Design and Patient Enrollment
The multi-site study has enrolled 303 patients and collected 479 voided urine samples. Recruitment is ongoing, with a target of 400 to 500 adult participants, aiming for 75 confirmed tumors. Currently, 46 enrolled patients have confirmed tumors. The trial includes patients under surveillance for non-muscle-invasive bladder cancer (NMIBC) with varying risk levels based on AUA/Society of Urologic Oncology guidelines. Eligible patients must have experienced previous urothelial carcinoma recurrence and be able to provide a voided urine sample. Exclusion criteria include prior genitourinary manipulation, total cystectomy, muscle-invasive bladder tumor, or pregnancy. The study is being conducted at Veterans Affairs and other medical centers across the United States.
Study Protocol and Endpoints
Patients provide voided urine samples at the initial visit and up to three successive surveillance cystoscopy visits over a two-year follow-up. Urine samples are tested with the Monitor/Monitor+ tests and central urine cytology to assess for recurrence. Cxbladder tests are alternated with cystoscopy at consecutive visits to directly compare the proposed pathway to the standard of care. Patients, physicians, and laboratory staff are blinded to Cxbladder results. Primary tumor tissue is collected when available for genotyping using DNA markers to assess urothelial carcinoma risk.
The primary endpoints of the study include sensitivity, specificity, negative predictive value, positive predictive value, and test-negative rate of the Cxbladder tests. Investigators propose that a clinical pathway utilizing the Monitor+ test could allow for Monitor+ negative patients to defer cystoscopy, while Monitor+ positive patients would be recalled for immediate evaluation. This approach could substantially reduce the burden of surveillance.
Potential Impact on Clinical Practice
The trial aims to demonstrate the safety of alternating Cxbladder with cystoscopy in urothelial carcinoma surveillance. It also seeks to support the inclusion of biomarkers as an alternative to cystoscopy in the AUA/National Comprehensive Cancer Network guidelines. Final completion of the LOBSTER study is anticipated for 2025, with publication of the results targeted for 2027.
