Testing the Addition of the Anti-cancer Drug, Cabozantinib, to the Usual Immunotherapy Treatment, Avelumab, in Patients With Metastatic Urothelial Cancer, MAIN-CAV Study

PRIMARY OBJECTIVE: I. To evaluate the effect of cabozantinib (cabozantinib S-malate) in combination with avelumab on overall survival (OS) compared to avelumab alone in patients with metastatic urothelial cancer (mUC) who did not progress during first-line platinum-based chemotherapy therapy, i.e. patients who had complete response (CR), partial response (PR) or stable disease (SD) after completion of first line platinum-based chemotherapy. SECONDARY OBJECTIVES: I. To evaluate the effect of cabozantinib in combination with avelumab on progression-free survival (PFS) compared to avelumab alone for maintenance treatment following initial first-line treatment in patients who had a CR, PR or SD upon completion of first-line platinum-based chemotherapy. II. To evaluate the safety and tolerability of cabozantinib in combination with avelumab in mUC compared to avelumab alone for maintenance treatment following initial first-line treatment in patients who had a CR, PR or SD upon completion of first-line platinum-based chemotherapy. III. To evaluate activity of cabozantinib in combination with avelumab based on Response Evaluation Criteria in Solid Tumors (RECIST) compared to avelumab alone for maintenance treatment following initial first-line treatment in patients who had a CR, PR or SD upon completion of first-line platinum-based chemotherapy. IV. Results of the primary analysis will be examined for consistency, while accounting for the stratification factors and/or covariates of baseline quality of life (QOL) and fatigue. V. To evaluate the activity of cabozantinib in combination with avelumab compared to avelumab alone based on PD-L1 status of patients' tumors. QUALITY OF LIFE (QOL) OBJECTIVES: I. To compare quality-adjusted survival between patients randomized to receive cabozantinib and avelumab versus (vs.) avelumab alone using the European Quality of Life Five Dimension Five Level Scale Questionnaire (EQ-5D-5L). II. To compare patient-reported fatigue as assessed by the Patient Reported Outcomes Measurement Information System (PROMIS)-Fatigue 4a from baseline through 12 months between patients randomized to receive cabozantinib and avelumab vs. avelumab alone. III. To compare patient-reported global health status/quality of life as assessed by the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ)-Core (C)30 from baseline through 12 months between patients randomized to receive cabozantinib and avelumab vs. avelumab alone. IV. To compare scale scores of the EORTC QLQ-Bladder Cancer Muscle-Invasive (BLM)30 (urinary symptoms, urostomy problems, catheter problems, future perspectives, abdominal bloating and flatulence, body image, sexual function) at 3, 6, 12, 18, and 24 months between patients randomized to receive cabozantinib and avelumab vs. avelumab alone. V. To compare scale scores of the EORTC QLQ-C30 (global health status/quality of life; physical, role, emotional, cognitive, and social function; symptoms) at 3, 6, 12, 18, and 24 months between patients randomized to receive cabozantinib and avelumab vs. avelumab alone. OUTLINE: Patients are randomized to 1 of 2 arms. ARM A: Patients receive avelumab intravenously (IV) over 60 minutes on days 1 and 15 of each cycle. Cycles repeat every 28 days for 24 months in the absence of disease progression or unacceptable toxicity. Patients also undergo bone scan at screening and undergo computed tomography (CT) or magnetic resonance imaging (MRI) and biospecimen collection throughout the trial. Patients may undergo urine sample collection as clinically indicated. ARM B: Patients receive avelumab IV over 60 minutes on days 1 and 15 of each cycle and cabozantinib orally (PO) daily on days 1-28 of each cycle. Cycles repeat every 28 days for 24 months in the absence of disease progression or unacceptable toxicity. Patients also undergo bone scan at screening and undergo CT or MRI and biospecimen collection throughout the trial. Patients may undergo urine sample collection as clinically indicated. After completion of study treatment, patients are followed every 30 days through 90 days, then every 3 months for 5 years.