(UroToday.com) The 2025 American Society of Clinical Oncology Genitourinary (ASCO GU) cancers symposium held in San Francisco, CA between February 13th and 15th 2025, was host to the Trials in Progress Poster Session B: Urothelial Carcinoma. Dr. Marie-Pier St-Laurent presented trial in progress poster 889: A phase 2/3 multicenter trial evaluating safety and efficacy of a new mucoadhesive gemcitabine suspension for ablation of upper tract urothelial carcinoma.
Kidney-sparing surgery for upper tract urothelial carcinoma (UTUC) remains limited and Nephroureterectomy (NU) is often required for recurrent or high-volume low-grade UTUC.
Despite Mitomycin C in hydrogel form showing efficacy in the treatment of low-grade upper tract urothelial carcinoma (LG UTUC), with 41 patients achieving a complete response and a median duration of response of 47.8 months in the OLYMPUS trial, there was a concerning rate of stricture (44%). (1) Furthermore, this form of Mitomycin C remains not widely available worldwide. On the other hand, Gemcitabine has proven effective in treating and preventing recurrence of urothelial carcinoma of the bladder, with limited side effects
This investigator-initiated, prospective, multicenter, single-arm trial (NCT06124976) aims to evaluate the efficacy and safety of ST-02 (mucoadhesive gemcitabine paste) for chemo-ablation of low-grade upper tract urothelial carcinoma (UTUC).
The investigational drug is a mucoadhesive gemcitabine polymer suspension. The active compound, gemcitabine hydrochloride, is diluted in a water-free polymer suspension that forms a gel and adheres to the urothelium upon contact with water or urine. The maximum dose is 200 mg of gemcitabine suspended in 10 mL of diluent, providing a concentration of 20 mg/mL
The primary objective is to evaluate the complete response (CR) rate at 3 months after the first instillation. Key secondary objectives include assessing the durability of response at 12 months in patients who achieve CR at 3 months, as well as evaluating the safety and tolerability of ST-02. The trial is divided into two phases: Phase 2 will enroll 30 participants, and if more than 8 CRs are observed, the study will expand to Phase 3, with an additional 40 participants, bringing the total to 70.
The trial inclusion criteria are:
- Primary or recurrent LG, non-invasive UTUC in the renal pelvis/calyces
- At least 1 measurable and biopsy-confirmed LG tumour (5-15mm)
- No active UTI
- All sexually active participants with reproductive potential must agree to use adequate contraceptive method, for at least 48 h after each instillation. Negative pregnancy test required for female of childbearing potential prior to instillation
- ECOG ≤2 (Karnofsky ≥60), life expectancy > 12mo
- Participants must have adequate organ and bone marrow function
Exclusion criteria, as reported by Dr. St-Lauren,t are:
- Received BCG treatment for UTUC within 6 weeks prior to initial ST-02 treatment visit
- History of high-grade NMIBC within the past 6 months
- Prior MIBC in the past 2 yrs
- Actively being treated or intend to be treated with intravesical (excluding SIC), or systemic chemotherapy during the duration of the trial
- Currently receiving another investigational agent or involved in a clinical trial with an investigational product within the past 30 days prior to initial ST-02 treatment visit
The trial design includes a screening phase where patients undergo ureteroscopy to confirm low-grade upper tract urothelial carcinoma (LG UTUC) with residual tumors ranging from 5-15 mm. Once enrolled, patients receive an induction of six weekly instillations of ST-02 via nephrostomy tube or ureteral catheter. If disease-free, they proceed to maintenance instillations of ST-02, followed by ureteroscopy every 3 months with a dose instillation of ST-02 until 12 months after the first surveillance. The schedule of activities is outlined below:
Presented by: Marie-Pier St-Laurent, MD, Urologic Oncology Fellow at the University of British Columbia, Vancouver General Hospital. BC, Canada.
Written by: Julian Chavarriaga, MD – Urologic Oncologist at Cancer Treatment and Research Center (CTIC) via Society of Urologic Oncology (SUO) Fellow at The University of Toronto. @chavarriagaj on Twitter during the 2025 Genitourinary (GU) American Society of Clinical Oncology (ASCO) Annual Meeting, San Francisco, CA, Thurs, Feb 13 – Sat, Feb 15, 2025.
Related content: Mucoadhesive Gemcitabine Formulation for Upper Tract Urothelial Carcinoma - Marie-Pier St-Laurent
Reference:
- Pierorazio PM, Kleinmann N, Shabsigh A, Hu B, Raman JD, Kaimakliotis H, et al. Long-Term Outcomes of Primary Chemoablation of Low-Grade Upper Tract Urothelial Carcinoma With UGN-101, a Mitomycin Reverse Thermal Gel. Journal of Urology [Internet]. [cited 2025 Feb 6];0(0). Available from: https://doi.org/10.1097/JU.0000000000004331