Hepzato Kit and Opdualag for Metastatic Melanoma and Liver Metastasis

Inclusion Criteria: * Histologically or cytologically confirmed metastatic melanoma with liver metastasis (LM). Liver biopsy positive for presence of melanoma metastases is required. * 0-1 line of prior systemic therapy in the unresectable/metastatic setting - prior adjuvant anti-programmed cell death-1 (anti-PD-1) or BRAF/MEK targeted therapy is considered 1 line of prior systemic therapy if less than 6 months from the last treatment. * Evaluable/measurable disease according to RECIST v1.1. * Demonstrate adequate organ function; all screening labs to be obtained within 28 days prior to registration. * Patients must weigh greater than or equal to 35 kilograms (due to possible size limitations with respect to percutaneous catheterization of the femoral artery and vein using the Delcath Hepatic Delivery System). Exclusion Criteria: * Prior treatment with HEPZATO KIT™ or nivolumab and relatlimab (Opdualag™) * Radiotherapy is permitted within 30 days prior to C1D1 as long as radiation is given with palliative intent and towards a non-target lesion. * History of hypersensitivity or treatment discontinuation due to grade 3+ immune-related adverse events (irAEs) from prior anti-PD-(L)1 therapy. Patients who are able to successfully resume immune checkpoint therapy without recurrence of grade 3 irAEs are eligible to participate. * Symptomatic or uncontrolled brain metastases, leptomeningeal disease, or spinal cord compression not definitively treated with surgery or radiation. * Prednisone use greater than or equal to 10 mg/d or equivalent * Organ transplant recipients