Conference Summary: Latest Progress of the Phase 1/2 Study of SIM0237 in BCG-unresponsive High-risk NMIBC
【Body: Mode B – Academic Deep Interpretation】
Editor’s Note: During a recent academic session, Professor Dingwei Ye (Prof. Dingwei Ye) from Fudan University Shanghai Cancer Center provided an in-depth interpretation of the Phase 1/2 clinical study data for SIM0237—an anti-PD-L1/IL-15 variant fusion protein—specifically in patients with Bacillus Calmette-Guérin (BCG)-unresponsive high-risk non-muscle-invasive bladder cancer (NMIBC).
01 Background and Mechanism: Synergistic Effects of Immune Checkpoint Inhibition and Cytokines
Clinical options remain limited for patients with high-risk NMIBC who are unresponsive to BCG, making the search for effective bladder-sparing therapies a top priority. Professor Dingwei Ye noted that previous studies have shown preliminary clinical efficacy of anti-PD-1 monotherapy combined with IL-15 agonists in this population. SIM0237 is a novel anti-PD-L1/IL-15 variant fusion protein designed to activate the immune system through a dual mechanism: blocking the PD-L1 pathway to relieve immune suppression while utilizing the IL-15 variant to specifically promote the proliferation and activation of NK cells and T cells, thereby enhancing anti-tumor cytotoxicity.
02 Trial Design and Baseline Characteristics: Focus on High-risk BCG-unresponsive Populations
The Phase 1/2 study of SIM0237 included both dose-escalation and dose-expansion phases. As of the data cutoff date of November 28, 2025, a total of 49 patients were enrolled to receive SIM0237 monotherapy via intravesical instillation. All participants had received adequate prior BCG therapy and met the criteria for BCG-unresponsive disease. • Patient Classification: The cohort included 14 patients with Carcinoma in Situ (CIS) and 35 patients with papillary-only tumors. • Study Phase: The reported data focused on the monotherapy dose evaluation and expansion components of the study.
03 Clinical Efficacy: Analysis of Benefit in CIS and Papillary Populations
The results demonstrated that SIM0237 achieved significant clinical benefit across both high-risk patient subgroups. • CIS Population: Among the 14 CIS patients, 10 had at least one post-baseline tumor assessment. Of these, 8 patients achieved a Complete Response (CR), resulting in a CR rate of 80%. The median Duration of Response (mDOR) was not yet mature, with a 71.4% probability of maintaining CR at 12 months. • Papillary-only Population: In the 35 patients with papillary tumors, the median Disease-Free Survival (mDFS) was not yet mature, and the 12-month DFS rate reached 65.8%. Addressing the relatively small sample size of the CIS cohort, Professor Ye mentioned that while 14 cases are representative for a Phase 1/2 trial, further validation in larger cohorts is required to confirm long-term efficacy.
04 Safety and Tolerability: Favorable Profile of Intravesical Instillation
With a median follow-up of 6.7 months, intravesical instillation of SIM0237 demonstrated a favorable safety profile and excellent tolerability: • Dose-Limiting Toxicity (DLT): No DLTs were observed during the trial. • Treatment-Related Adverse Events (TRAE): The incidence of TRAEs was approximately 10%. • Administration Stability: The percentage of dose interruptions was extremely low, confirming that the intravesical route of administration for this agent is safe and can support long-term treatment adherence.
05 Conclusion and Outlook: Phase 3 Clinical Trial Planning Underway
Professor Dingwei Ye concluded that SIM0237 monotherapy exhibits clear anti-tumor activity with a manageable safety risk in BCG-unresponsive high-risk NMIBC patients. Based on these positive early results, a Phase 3 clinical trial for this patient population is currently under planning. This agent has the potential to become a significant new bladder-sparing option for high-risk NMIBC patients following BCG failure.
