Background: In China, UTUC affects 9.3% - 19.9% of urothelial carcinoma(UC) patients(Pts), comparing to 5%-10% in western countries. Radical nephroureterectomy (RNU) is the standard of care for locally advanced UTUC; however, patient prognosis remains suboptimal, and previous studies have shown a controversial survival benefit of postoperative adjuvant chemotherapy in pts with UTUC. Immune checkpoint inhibitors(ICI) have been demonstrated to improve disease-free survival (DFS) in pts after adjuvant therapy for UC, but the data from UTUC studies is limited. This study is intended to evaluate real-world study data on whether Tisle with/without GC is able to achieve better survival benefit in pts with UTUC. Methods: UTUC pts with clinical diagnosis of T1N1 or T2-T4aN0-1M0, ECOG ps of 0-1, could tolerate surgery and had adequate renal functional reserve after surgery. Enrolled pts underwent RNU surgery and adjuvant therapy was started within 90 days after surgery. ICI: 200 mg in day1(D1), Q3w regimen, when to discontinue the drug was assessed by clinicians, and the reasons for disease progression and intolerable toxicity; GC chemotherapy: gemcitabine 1000 mg/m² D1, D8, cisplatin 70 mg/m² D2, up to 6 (0-6) cycles. Primary endpoint: 3-year Overall survival (OS) rate; secondary endpoints included 5-year OS rate, tumor-related survival (CSS) and safety. Results: A total of 60 pts received the above treatment from Jan 2020 to Dec 2022, of whom 5 pts were considered to have metastases at initial diagnosis at further evaluation and were finally evaluated for safety only. Fifty-five pts were evaluable for response, with a median follow-up time of 21.5 (3-33) months, and 70.91% (39/55) of pts were followed up for more than 12 months. The OS rate was 93.14% at 1 year and 76.21% at 2 years. Tisle was administered for a median of 6 (1-14) cycles, with a 7.19% and 24.79% lower risk of death at 1 and 2 years in pts with Tisle ≥ 3 cycles compared with pts with Tisle < 3 cycles (HR: 0.368, 95% CI (0.076-1.781); p = 0.162). GC was administered for a median of 3 (0-6) cycles, with a 3.7% and 24.8% lower risk of death at 1 and 2 years in pts with GC＞2 cycles compared with pts with GC≤2 cycles (HR: 0.218, 95% CI (0.045-0.970); p = 0.110). The incidence of treatment-related adverse reactions (trAEs) of any grade was 91.64%; the incidence of trAEs of grade 3-4 was 18.33%, mainly manifested as leukopenic, gastrointestinal reaction and thrombocytopenia. The incidence of immune-related adverse reactions (irAEs) was 25%, and no irAEs of grade 3 or higher were found. The enrollment and follow-up of the present study are currently ongoing. Conclusions: Encouraging efficacy data and safety have been preliminarily observed with adjuvant Tisle with/without GC chemotherapy in high-risk pts after UTUC surgery. Final results also need to be observed in further studies.