ST-02 Treatment for Upper Tract Urothelial Carcinoma

Inclusion Criteria: * Adult (≥ 18 years) male or female * Primary or recurrent low-grade (LG), noninvasive (Ta) Upper Tract Urothelial Carcinoma (UTUC) in the renal pelvis, infundibulum, and/or calyces, based on ureteroscopy, biopsy and cytology (disease assessment URS) performed within 8 weeks prior to or during the Screening Visit * At least 1 measurable papillary tumor measuring 5-15 mm * Low grade tumor(s) in the ipsilateral ureter. Every attempt should be made to ablate this tumor completely, but residual ipsilateral ureteral tumor is not an exclusion criterion. * Prior fully ablated low grade bladder tumor(s), without the need for intravesical therapy except for single-dose chemotherapy * A life expectancy of greater than 12 months * No active untreated urinary tract infection (UTI) as confirmed by urine culture or urinalysis * Women of Child bearing potential (WoCBP) and Males who have a WoCBP partner require a negative pregnancy test at the Screening visit and must use two acceptable contraceptives methods until six months post-treatment * All sexually active males must agree to use a condom during intercourse, for at least 48 h after each instillation * eGFR ≥10 mL/min; weekly creatinine monitoring recommended during treatment for participants with eGFR \<30 mL/min or a solitary functional kidney Exclusion Criteria: * Have received Bacillus Calmette - Guerin (BCG) treatment for UTUC within 6 weeks prior to Visit 1 (D1) * Pregnant (positive urine pregnancy test), planning pregnancy during trial, breast-feeding, or of childbearing potential without reliable contraception * Unresolved infection requiring active treatment with systemic antimicrobial drugs * History of high-grade non-muscle invasive bladder cancer within the past 6 months * History of muscle-invasive bladder cancer during the past 2 years * Actively being treated or intend to be treated with intravesical or systemic chemotherapy during the duration of the trial * Urinary obstruction in the ipsilateral Upper Urinary Tract (UUT) * Any contraindicated to gemcitabine or sensitivity to gemcitabine or any of the ST-02 ingredients * Currently receiving another investigational agent or involved in a clinical trial with an investigational product within the past 30 days prior to Visit 1 (D1) * Active hepatitis B (chronic or acute) or active hepatitis C infection