The study goal is to evaluate the effectiveness in clinical practice of Avelumab as first line maintenance therapy in patients with locally advanced or metastatic Urothelial Carcinoma, who have not progressed after first line platinum-based treatment.

Study is performed at national hospitals from approximately 22 different sites and expecting to recruit 120 patients.

Patients understanding the nature of the study by providing their informed consent prior to participation.

• Patients of both sexes diagnosed with locally advanced or metastatic Urothelial Carcinoma, stage IV disease before first line with carboplatin/cisplatin-based chemotherapy. No disease progression after four-six cycles of ChT according to the Response Evaluation Criteria in Solid Tumor with a treatment free interval of 4-10 weeks before Avelumab initiation date.
• Patients who started Avelumab as maintenance therapy in first line after 21/Jan./2021 and before 27/Apr./2022 (both dates included).

Multicentre, observational, ambispective (retrospective and prospective) study to evaluate the real-world evidence of Avelumab as maintenance therapy in patients diagnosed with Urothelial Carcinoma (WHO classification) and previously treated with platinum-based treatment in first line. Study is performed at national hospitals from approximately 22 different sites and expecting to recruit 120 patients. Patients are selected based on the existing medical record of have been treated with Avelumab as maintenance therapy in first line before initiating the study (retrospective data); patients who continues receiving Avelumab after inclusion will also contribute to data collection until the end of treatment or end of study (prospective data).

According to mUC incidence and the selective inclusion criteria from this study of having initiated Avelumab as maintenance therapy in 1L between EMA approval date (Jan. 2021) and date of national reimbursement prize (Apr.2022), which is a narrow period of time to recruit the necessary number of candidates, therefore, prospective data from each participant patient will be a key to ensure the assessment of the study objective eventually.

Investigators will review the medical history of patients treated or under treatment of Avelumab and select chronologically those who matches the inclusion criteria. Patients will be informed during a regular follow up visit about the nature of the study and requested to sign the patient consent form once the decision of participating is made. At this point, the retrospective data from patients is collected (such as demographics, toxicity, anthropometrics, vital signs, comorbidities, hemogram, dosage modification etc.) previous adverse reactions (ARs) and serious adverse reaction (SARs) related to Avelumab. Included patients, that continues under Avelumab treatment will be monitored by investigators and prospective data from them will be collected during follow up visits and/or from electronic medical records (eMR).

Deceased patient who fulfils the inclusion criteria can be also included, being able to access to its clinical data at the beginning of the study according to Regulation (EU) 2016/679 of the European Parliament and of the Council of 27 April 2016 on the protection of natural persons with regard to the processing of personal data and on the free movement of such data, and repealing Directive 95/46/EC (General Data Protection Regulation) and the Spanish Organic Law 3/2018 of 5th December, on the protection of personal data and digital rights. Additionally, the investigator team will consult in the eMR of deceased patients to ensure that they did not express in life opposition to the use of their data for investigational purposes.

Inclusion Criteria:

• Patients understanding the nature of the study by providing their informed consent prior to participation.
• Patients of both sexes diagnosed with locally advanced or metastatic Urothelial Carcinoma, stage IV disease (AJCC ed. 8th, 2017) before first line with carboplatin/cisplatin-based chemotherapy (ChT). No disease progression after four-six cycles of ChT according to the Response Evaluation Criteria in Solid Tumor (RECIST 1.1) with a treatment free interval of 4-10 weeks before Avelumab initiation date.
• Patients who started Avelumab as maintenance therapy in first line after 21/Jan./2021 and before 27/Apr./2022 (both dates included).

Patients diagnosed with locally advanced or metastatic Urothelial Carcinoma who have not progressed after first line platinum-based treatment and who received or are receiving Avelumab as the first-line maintenance therapy in routine clinical practice.