Prognostic Value of miR-145 in HER2-Positive Locally Advanced or Metastatic Urothelial Carcinoma Treated with Disitamab Vedotin.

Disitamab vedotin (RC48), a HER2-targeted antibody-drug conjugate, has shown promising activity in locally advanced or metastatic urothelial carcinoma (la/mUC), but clinically useful biomarkers remain lacking. In this retrospective single-center real-world study, we evaluated the efficacy of RC48 and the clinical relevance of tumor miR-145 expression in 136 patients with HER2-positive la/mUC treated between June 2022 and October 2024. Clinical outcomes included objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS). The ORR and DCR were 64.0% and 75.7%, respectively. Median OS was 15.5 months (95% CI: 12.6-28.5), and median PFS was 9.2 months (95% CI: 7.1-11.8). In univariate Cox analysis, miR-145 was the only variable significantly associated with OS (HR = 0.676, p = 0.002). High miR-145 expression was associated with improved OS and a higher complete response rate than low expression. Time-dependent ROC analysis showed an AUC of 76.3% at 2 years, and decision curve analysis suggested potential clinical utility. These findings indicate that miR-145 may serve as a candidate prognostic biomarker for risk stratification in RC48-treated la/mUC.