Stereotactic Radiotherapy and Enfortumab Vedotin for the Treatment of Patients with Localized, Cisplatin Ineligible, Muscle Invasive Bladder Cancer

Inclusion Criteria

• Urothelial carcinoma of the urinary bladder stage cT2-4a (American Joint Committee on Cancer [CAJCC] 8th edition) N0M0 planned for radical cystectomy. Mixed cell types are allowed as long as urothelial component is > 50% AND no small cell/neuroendocrine or plasmacytoid/signet ring component
• Ineligibility for cisplatin-based chemotherapy based on treating physician assessment and any of the following “Galsky criteria”: renal insufficiency (Creatinine clearance [CrCl] < 60ml/min by standard institutional calculation method), >= grade 2 hearing loss, New York Heart Association (NYHA) class III heart failure; a combination of these; or patient refusal
• Age >= 18
• Performance status Easter Cooperative Oncology Group (ECOG) 0-1
• Absolute neutrophil count (ANC) >= 1500/mm^3
• Platelet count >= 100 x 10^9/L
• Hemoglobin ≥ 9 g/dL
• Serum bilirubin ≤ 1.5 × upper limit of normal (ULN) or ≤ 3 × ULN for subjects with Gilbert’s disease
• Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 2.5 × ULN
• No end stage renal disease requiring dialysis allowed
• All men, as well as women of child-bearing potential must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry, for the duration of study participation, and for 3 months following completion of study neoadjuvant therapy. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately. * A female of child-bearing potential is any woman (regardless of sexual orientation, marital status, having undergone a tubal ligation, or remaining celibate by choice) who meets the following criteria: ** Has not undergone a hysterectomy or bilateral oophorectomy; or ** Has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months)
• Ability to understand and the willingness to sign a written informed consent

Exclusion Criteria

• No prior systemic therapy (except prior therapy for non-muscle invasive bladder cancer > 12 months prior to registration) for bladder cancer or prior pelvic radiotherapy. Prior intra-vesical therapies are allowed, including Bacillus Calmette-Guerin (BCG) for non-muscle invasive bladder cancer. Prior chemotherapy for other cancers is allowed if given >= 1 year prior to study registration
• Baseline >= grade 2 sensory or motor neuropathy
• Subjects may not be receiving any other investigational agents for the treatment of the cancer under study
• History of allergic reactions attributed to compounds of similar chemical or biologic composition to enfortumab vedotin or other agents used in study
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness or social situations that, in the opinion of the investigator, would limit compliance with study requirements
• Subjects must not be pregnant or nursing due to the potential for congenital abnormalities and the potential of this regimen to harm nursing infants