Enfortumab Vedotin and Pembrolizumab vs. Chemotherapy Alone in Untreated Locally Advanced or Metastatic Urothelial Cancer

Inclusion Criteria:

* Histologically documented, unresectable locally advanced or metastatic urothelial carcinoma
* Measurable disease by investigator assessment according to RECIST v1.1

  * Participants with prior definitive radiation therapy must have measurable disease per RECIST v1.1 that is outside the radiation field or has demonstrated unequivocal progression since completion of radiation therapy
* Participants must not have received prior systemic therapy for locally advanced or metastatic urothelial carcinoma with the following exceptions:

  * Participants that received neoadjuvant chemotherapy with recurrence \>12 months from completion of therapy are permitted
  * Participants that received adjuvant chemotherapy following cystectomy with recurrence \>12 months from completion of therapy are permitted
* Must be considered eligible to receive cisplatin- or carboplatin-containing chemotherapy, in the investigator's judgment
* Archival tumor tissue comprising muscle-invasive urothelial carcinoma or a biopsy of metastatic urothelial carcinoma must be provided for PD-L1 testing prior to randomization
* Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0, 1, or 2
* Adequate hematologic and organ function

Exclusion Criteria:

* Previously received enfortumab vedotin or other monomethyl auristatin E (MMAE)-based antibody-drug conjugate (ADCs)
* Received prior treatment with a programmed cell death ligand-1 (PD-(L)-1) inhibitor for any malignancy, including earlier stage urothelial cancer (UC), defined as a PD-1 inhibitor or PD-L1 inhibitor
* Received prior treatment with an agent directed to another stimulatory or co inhibitory T-cell receptor
* Received anti-cancer treatment with chemotherapy, biologics, or investigational agents not otherwise prohibited by exclusion criterion 1-3 that is not completed 4 weeks prior to first dose of study treatment
* Uncontrolled diabetes
* Estimated life expectancy of less than 12 weeks
* Active central nervous system (CNS) metastases
* Ongoing clinically significant toxicity associated with prior treatment that has not resolved to ≤ Grade 1 or returned to baseline
* Currently receiving systemic antimicrobial treatment for active infection (viral, bacterial, or fungal) at the time of randomization. Routine antimicrobial prophylaxis is permitted.
* Known active hepatitis B, active hepatitis C, or human immunodeficiency virus (HIV) infection.
* History of another invasive malignancy within 3 years before the first dose of study drug, or any evidence of residual disease from a previously diagnosed malignancy
* Documented history of a cerebral vascular event (stroke or transient ischemic attack), unstable angina, myocardial infarction, or cardiac symptoms consistent with New York Heart Association (NYHA) Class IV within 6 months prior to randomization
* Receipt of radiotherapy within 2 weeks prior to randomization
* Received major surgery (defined as requiring general anesthesia and \>24 hour inpatient hospitalization) within 4 weeks prior to randomization
* Known severe (≥ Grade 3) hypersensitivity to any enfortumab vedotin excipient contained in the drug formulation of enfortumab vedotin
* Active keratitis or corneal ulcerations
* History of autoimmune disease that has required systemic treatment in the past 2 years
* History of idiopathic pulmonary fibrosis, organizing pneumonia, drug induced pneumonitis, idiopathic pneumonitis, or evidence of active pneumonitis on screening chest computed tomography (CT) scan
* Prior allogeneic stem cell or solid organ transplant
* Received a live attenuated vaccine within 30 days prior to randomization