This hypothetical first-in-human study is designed to evaluate the safety, feasibility, and preliminary anti-tumor activity of an allogeneic dual-target Nectin-4/HER2 CAR-NK cell product in adults with relapsed/refractory locally advanced or metastatic urothelial carcinoma. Based on public urothelial-cancer evidence, Nectin-4 was selected as the lead antigen because it has the strongest disease-specific clinical validation; HER2/ERBB2 was chosen as the secondary co-target to broaden tumor coverage and reduce antigen-escape risk. EpCAM is not selected as a therapeutic co-target in this example because of broader normal epithelial expression and weaker tumor specificity in urothelial carcinoma.

Advanced urothelial carcinoma remains a high-unmet-need disease after platinum-based chemotherapy, PD-1/PD-L1 inhibition, and-where available-Nectin-4- or HER2-directed therapies. Public trial activity in urothelial cancer strongly supports Nectin-4 as the best validated anchor antigen, while HER2 identifies a clinically relevant and actionable subset. Because both antigens can be heterogeneous, this example protocol uses mandatory pre-treatment central biomarker testing and favors fresh biopsy after the most recent systemic therapy, especially after prior enfortumab vedotin or HER2-directed treatment.

The investigational product in this example is an allogeneic cord-blood-derived CAR-NK cell therapy engineered to co-recognize Nectin-4 and HER2/ERBB2 and to include an inducible caspase-9 safety switch. The product is administered intravenously after lymphodepletion with fludarabine and cyclophosphamide. Part A uses a 3+3 dose-escalation design with sentinel dosing at each new level to identify the maximum tolerated dose (MTD) and/or recommended Phase 2 dose (RP2D). Part B expands the RP2D to better characterize safety and generate preliminary efficacy data.

To better address the original target shortlist, the protocol also incorporates exploratory translational analyses of EpCAM expression, circulating tumor DNA, tumor antigen co-expression, NK-cell persistence, and mechanisms of resistance. This allows future protocol versions to revisit EpCAM only if patient-specific biomarker data show a favorable therapeutic window.

Tumor assessments are performed by RECIST v1.1 for measurable metastatic disease.

Patients are monitored closely for dose-limiting toxicities (DLTs), cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), graft-versus-host disease (GvHD), infusion reactions, and organ-specific on-target/off-tumor toxicities. Because HER2 is used as a secondary antigen, this example explicitly incorporates enhanced cardiopulmonary monitoring and conservative dose-escalation rules.

Inclusion Criteria:

• Age 18-75 years at consent.
• Histologically confirmed urothelial carcinoma of the bladder, ureter, renal pelvis, or urethra that is unresectable locally advanced or metastatic.
• Disease progression after, intolerance to, or ineligibility for standard therapy, including platinum-based chemotherapy and PD-1/PD-L1 blockade when appropriate for the patient and region. Prior enfortumab vedotin and prior HER2-directed therapy are allowed, but a fresh biopsy is strongly preferred after the latest systemic regimen.
• At least one measurable lesion per RECIST v1.1.
• Tumor tissue available for central review demonstrating Nectin-4 positivity (for example, IHC ≥1+ in ≥10% tumor cells) and HER2 status assessed by IHC/ISH. At least one of the selected therapeutic targets must be present; dose expansion preferentially enrolls Nectin-4-positive disease.
• ECOG performance status 0-1.
• Adequate bone marrow, hepatic, renal, and coagulation function.
• Life expectancy of at least 12 weeks.
• Negative pregnancy test for women of childbearing potential and agreement to use highly effective contraception during study treatment and follow-up as defined in the protocol.
• Ability to understand and sign informed consent.

Exclusion Criteria:

• Active or untreated central nervous system metastases or leptomeningeal disease. Previously treated CNS disease is allowed if clinically stable and off escalating corticosteroids.
• Prior allogeneic hematopoietic stem cell transplant, prior solid-organ transplant, or active graft-versus-host disease.
• Clinically significant autoimmune disease requiring systemic immunosuppression within the defined washout window.
• Uncontrolled infection, including uncontrolled hepatitis B, hepatitis C, HIV, sepsis, or active tuberculosis.
• Clinically significant cardiac disease, active myocarditis, unstable angina, recent myocardial infarction, uncontrolled arrhythmia, or clinically meaningful decline in left ventricular ejection fraction that would increase risk from HER2-directed cell therapy.
• Clinically significant pulmonary disease (for example, uncontrolled interstitial lung disease or oxygen-dependent respiratory compromise).
• Use of systemic corticosteroids or other immunosuppressive medications above protocol-allowed limits within the washout window.
• History of severe hypersensitivity to fludarabine, cyclophosphamide, or cell-product excipients.
• Pregnancy or breastfeeding.
• Another active malignancy requiring systemic therapy or likely to interfere with protocol assessments, except for protocol-allowed low-risk cancers.