Extracorporeal photopheresis for the treatment of steroid-refractory immune related adverse events from immune checkpoint inhibitor therapy: a multi-center phase Ib/II clinical trial

Severe immune-related adverse events (irAE) in cancer patients receiving immune checkpoint inhibitors (ICI) require treatment interruption and immunosuppression. Based on prior preclinical data, in this prospective, single arm, non-randomized phase-Ib/II clinical trial we test the activity of Extracorporeal Photopheresis (ECP) against steroid-refractory irAEs in 30 patients (EudraCT-No.:2021-002073-26). The primary endpoint is the evaluation of the safety of ECP treatment for patients with ICI-induced irAEs. The study meets its pre-specified primary endpoint of less than 50% of patients developing ECP-related severe adverse events (SAE). No ECP-related SAE is observed and ECP-related AEs are reported in 20% (6/30) of patients. Overall response rate for all irAEs is 96.3% (CI 81.0-99.91). Colitis-, hepatitis- and dermatitis-specific response rates are 100% (13/13), 86.7% (13/15) and 100% (3/3), respectively. Secondary endpoints include the assessment of response rate of irAE and overall survival. ECP therapy is associated with reduced granzyme-A/B/K, T-bet, interferon-γ and TNF in peripheral T cells and pro-inflammatory gene-expression in the intestinal tract. The 12-month overall survival rate is 84.3% (CI 63.4%-93.8%). Response correlates with a decrease in inflammatory gene expression in the intestinal tract. These results suggest that ECP is a safe treatment option for SR-irAEs and warrant further investigation in subsequent randomized clinical trials.