A Study to Evaluate the Efficacy and Safety of Autogene Cevumeran With Nivolumab Versus Nivolumab Alone in Participants With High-risk Muscle-invasive Urothelial Carcinoma (MIUC)

Inclusion Criteria:

• Participants must have the capacity to participate/enroll in the study and toprovide informed consent

• Histologically confirmed muscle-invasive UC (also termed transitional cell carcinoma [TCC]) of the bladder or upper urinary tract

• Tumor-node-metastasis (TNM ) classification (Union for International Cancer Control [UICC]/American Joint Committee on Cancer [AJCC] 7th edition) at pathologicalexamination of surgical resection specimen of (y)pT3-4 or (y)pN+ and M0

• Surgical resection of MIUC of the bladder or upper tract

• Participants who have received neoadjuvant chemotherapy (NAC), including antibodydrug-conjugate, either alone or in combination with a checkpoint inhibitor (CPI),are eligible

• Participants who have not received any prior NAC are also eligible, provided theymeet one of the following criteria, which would make them ineligible to receiveadjuvant cisplatin-based therapy: participant refusal, cisplatin ineligibility orinvestigator decision

• Tumor tissue must be provided for biomarker analysis

• Absence of residual disease and absence of metastasis, as confirmed by a negativebaseline computed tomography (CT) or magnetic resonance imaging (MRI) scan of thepelvis, abdomen, and chest no more than 28 days prior to randomization

• Full recovery from cystectomy or nephroureterectomy within 120 days followingsurgery

• Eastern cooperative oncology group (ECOG) performance status of 0 or 1

• Negative human immunodeficiency virus (HIV) test at screening

• Negative hepatitis B surface antigen (HbsAg) test at screening

• Positive hepatitis B surface antibody (HBsAb), or a negative HBsAb at screeningaccompanied by either of the following: negative total hepatitis B core antibody (HBcAb) or positive total HBcAb test followed by quantitative hepatitis B virus (HBV) deoxyribonucleic acid (DNA) < 500 international units/milliliter (IU/mL)

• Negative hepatitis C virus (HCV) antibody test at screening, or a positive HCVantibody test followed by a negative HCV ribonucleic acid (RNA) test at screening

Exclusion Criteria:

• Partial cystectomy in the setting of bladder cancer primary tumor or partialnephroureterectomy in the setting of renal pelvis primary tumor

• Any approved anti-cancer therapy, including chemotherapy, or hormonal therapy within 3 weeks prior to initiation of study treatment

• Adjuvant chemotherapy, immunotherapy, or radiation therapy for UC following surgicalresection

• Prior active malignancies within 3 years prior to randomization

• Treatment with a live, attenuated vaccine within 4 weeks prior to initiation ofstudy treatment