Real-World Use of Avelumab First-Line Maintenance for Locally Advanced or Metastatic Urothelial Carcinoma in Japan: Treatment Patterns, Effectiveness, and Safety.

Multiple first-line (1L) and subsequent systemic treatment options are now available for patients with locally advanced or metastatic urothelial carcinoma (la/mUC), making shared decision-making increasingly important. In addition to clinical trial data, clinicians need real-world data (RWD) that describes effectiveness, safety, and contemporary treatment sequences in clinical practice. One 1L treatment option for patients with la/mUC is platinum-based chemotherapy (PBC) followed by avelumab maintenance in patients without disease progression. This narrative review summarizes Japanese RWD from three complementary studies of avelumab 1L maintenance-post-marketing surveillance, JAVEMACS, and JAVEMACS-D. These studies show that avelumab maintenance has a predictable and acceptable safety profile in Japanese clinical practice and is being used in an older and more clinically heterogeneous population than that enrolled in JAVELIN Bladder 100. These RWD also describe frequent use of cisplatin-containing chemotherapy, individualized timing of transition to maintenance, and increasing use of enfortumab vedotin after avelumab. Of note, the interpretation of some of these findings requires caution because of immortal time bias, treatment selection bias, and patient attrition before maintenance initiation. Additionally, this sequential strategy applies to a selected population without progression after induction PBC and should be interpreted in the context of the current treatment landscape, which also includes intensified 1L combination treatment options such as enfortumab vedotin plus pembrolizumab and gemcitabine-cisplatin plus nivolumab. Overall, these Japanese RWD can complement randomized clinical trial data by informing discussion of treatment trajectories, feasibility, and trade-offs, thereby supporting more individualized and patient-centered treatment decisions in contemporary la/mUC clinical practice in Japan.