(UroToday.com) The 2024 GU ASCO annual meeting featured a urothelial carcinoma session and a presentation by Dr. Stephen Williams discussing population based trends in intravesical gemcitabine use among patients with high-risk non-muscle invasive bladder cancer. Although BCG remains the standard of care for newly diagnosed high-risk non-muscle invasive bladder cancer (NMIBC), intravesical gemcitabine use among patients with high-risk NMIBC has shown effectiveness towards preventing or delaying tumor recurrence. Data characterizing intravesical gemcitabine use and associated treatment patterns in the existing literature is limited, thus real world research of treatment patterns in the high risk NMIBC population is warranted to better understand intravesical gemcitabine utilization. This retrospective cohort study investigated intravesical gemcitabine users and reported their treatment patterns among SEER-Medicare enrollees newly diagnosed with high-risk NMIBC patients BCG naïve (no claims prior to the index date) or exposed to BCG therapy (at least one BCG claim prior to the index date).
Patients enrolled in Medicare Part A & B fee-for-service enrolled, with high-risk NMIBC, defined by Tis, Ta, T1, N0, M0, and ≥65 years with intravesical gemcitabine use between 2008-2020 were evaluated. Patients with missing TNM stage, low/ intermediate risk NMIBC, or other primary cancers were excluded. The index date was defined as the first claim of intravesical gemcitabine after high-risk NMIBC diagnosis, regardless of their prior BCG use. Patients were followed until the earliest event of death, end of Medicare Advantage enrollment, or data availability end (December 31, 2020):
Demographic and clinical characteristics were reported in the baseline period (12-month pre-index) and treatment patterns were reported calendar year post-index date for BCG-naïve and BCG-exposed cohorts.
There were approximately 293,000 unique bladder cancer patients identified, of which 37,762 (12.9%) met the criteria for high risk NMIBC during the specified time period. The final analysis set of 679 patients included 277 BCG-naïve (41%) and 402 BCG-exposed (59%) patients receiving intravesical gemcitabine. In both cohorts, the mean age was >75 years, ≥80% were male, and >90% were White. The mean national cancer index comorbidity index score was 0.85 (SD 0.7) for BCG-naïve and 0.63 (SD 0.7) for BCG-exposed. A higher proportion of patients with Ta tumors and lower proportion of T1 and Tis were noted in the BCG-naïve group at baseline:
Intravesical therapy use beyond a perioperative instillation during the baseline period was observed in 27.4% of BCG-naïve and 36.1% of BCG-exposed patients. The use of intravesical docetaxel (17.3% BCG-naïve, 20.4% BCG-exposed) and mitomycin (11.6% BCG-naïve, 17.2% BCG-exposed) were most common. From 2008-2020, the use of intravesical gemcitabine increased over the study period, most notably, since 2019:
The median number of intravesical gemcitabine doses in the BCG-naïve group was 6 (IQR 1,8) with mean of 28 (SD 43) days of retreatment interval. In BCG-exposed, the median number of intravesical gemcitabine doses was 6 (IQR 2,9) with mean of 23 (SD 26) days of retreatment interval. The percentages of patients who received 1, 2, 3, and 4 doses of intravesical gemcitabine are as follows:
Over 40% of the BCG-naïve cohort and over 30% of the BCG-exposed cohort did not receive a fourth dose. Docetaxel was used in combination with intravesical gemcitabine in 18.4% of the BCG-naïve cohort and 21.4% of the BCG-exposed cohort. There are several limitations of this study, including (i) the retrospective nature with the inherent limitations of administrative data, including potential inaccurate coding errors leading to misclassification of treatment and clinical outcomes, (ii) the study did not account for induction and maintenance phases of intravesical gemcitabine treatment, so the results should be interpreted with this consideration, and (iii) data used in this study were limited by the information recorded and translated into structured data element, and may not have been generalizable to the entire US population.
Dr. Williams concluded his presentation by discussing population based trends in intravesical gemcitabine use among patients with high-risk non-muscle invasive bladder cancer with the following take-home points:
- The use of intravesical gemcitabine in management of high risk NMIBC has increased dramatically since 2019 in overall intravesical treated patients
- Treatment duration of intravesical gemcitabine was observed to be suboptimal with the majority of patients stopping therapy within 4 months
- Given the increased practice and lack of phase 3 trials on intravesical gemcitabine use in the high risk NMIBC setting, studies of real world clinical outcomes will become important in understanding the clinical benefits and risks of intravesical gemcitabine and the optimal duration of treatment
Presented by: Stephen B. Williams, MD, MS, University of Texas Medical Branch at Galveston, Galveston, TX
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Associate Professor of Urology, Georgia Cancer Center, Wellstar MCG Health, @zklaassen_md on Twitter during the 2024 American Society of Clinical Oncology Genitourinary (ASCO GU) Cancers Symposium, San Francisco, CA, January 25th – January 27th, 2024