#0741

Comparing low-dose and full-dose intravesical Sii-Onco BCG in patients with intermediate and high risk NMIBC: A prospective randomised study

J. Hsu¹, P. Cheng^1,2, C. Chao¹, C. Tsai^1,3, B. Chiu¹, S. Chung¹, S. Yii^1,2

¹Far Eastern Memorial Hospital, Divisions of Urology, Department of Surgery, New Taipei City, Taiwan
²National Taiwan University, Department of Biomedical Engineering, College of Medicine and College of Engineering, Taipei, Taiwan
³Yuan Ze University, Department of Electrical Engineering, Taoyuan, Taiwan

Introduction:

Bacillus Calmette-Guerin (BCG) is a standard immunotherapy for non-muscle-invasive bladder cancer (NMIBC) that significantly reduces recurrence and progression risks. However, the optimal BCG dose remains unclear, with dose reduction explored to minimize side effects. During the global BCG shortage, the NCCN guidelines recommend using one-third of the standard dose for induction therapy, along with maintenance therapy, based on clinical trials showing similar efficacy between the reduced and standard doses. This study compares the safety and side effects of full-dose (120 mg) versus one-third dose (40 mg) of Sii Onco BCG in NMIBC patients.

Material and methods:

From August 2023, we prospectively enrolled patients with histologically confirmed, completely resected T1, high-grade Ta, low-grade Ta with multifocality, tumor size ≥3 cm, recurrence within one year, and carcinoma in situ (CIS). Patients underwent transurethral resection followed by repeated intravesical BCG instillations (40 mg or 120 mg) per the induction and maintenance schedule at 3, 6, 12, 15, 18, and 24 months. Tumor recurrence and progression were monitored with cystoscopy, and adverse effects were assessed using the Common Terminology Criteria for Adverse Events (CTCAE) and Overactive Bladder Symptom Score (OABSS). The association between a single risk factor (i.e., clinically relevant variables) and the occurrence of adverse events across different dosage levels was assessed using generalized estimating equations (GEE). The GEE model specified a logit link function and assumed an autoregressive correlation structure of order 1 (AR(1)) to account for within-subject correlations arising from repeated measurements.

Results:

A total of 32 patients were enrolled, with 15 in low-dose group and 17 in full-dose group. The average number of BCG instillations was 10.3 for the low-dose group and 8.4 for the full-dose group (p = 0.003). No significant differences were observed between groups regarding gender, age, tumor number, size, or risk classification. The severity and incidence of side effects were similar, with frequency and dysuria being the most common. The full-dose group had a higher OABSS (OR 1.83), and three patients discontinued BCG instillation due to discomfort, resulting in a 18% discontinuation rate, while none discontinued in the low-dose group.