Treatment of Immune-related Adverse Events Refractory to Standard Therapy and Associated Changes in Immunophenotype

Inclusion Criteria: 1. Subjects must we willing and able to comply with scheduled visits and must have given written informed consent. 2. irAE after immune checkpoint inhibitor therapy (PD-1/PD-L1 or PD-1 + CTLA4 blockade) 3. irAE refractory to therapy with corticosteroids or inability to taper corticosteroids to prednisone equivalent \<= 5mg. An irAE is defined as refractory if corticosteroids do not improve symptoms within 72 hours. The inability to taper corticosteroids is defined as relapse on standard tapering of 1 mg/kg corticosteroid over 28 days. Exclusion Criteria: 1. Contraindications for the treatment with ECP including a known sensitivity to psoralen compounds such as 8-MOP, comorbidities that may result in photosensitivity, aphakia, history of heparin-induced thrombocytopenia, unsatisfactory cardio-circulatory function, low hematocrit values 2. Pregnancy 3. Body weight less than 40 kg.