Programmed cell death ligand 1 (PD-L1) is frequently expressed in cutaneous squamous cell cancer (CSCC) and preliminary data from an ongoing clinical trial suggest that programmed death receptor 1 (PD-1) checkpoint inhibitors may be useful to treat patients with metastatic non-melanoma skin cancer. To report a series of three patients with advanced CSCC treated with nivolumab, showing that commercially available PD-1 checkpoint inhibitors may be useful in non-melanoma skin cancer patients without access to a clinical trial. All patients had previous chemotherapy. All cancers were PD-1 ligand (PD-L1)-positive based on immunohistochemistry. Patients consented to off-label therapy with nivolumab, which is commercially available in Switzerland. Two patients had a partial tumour response, and have been receiving therapy for more than 12 months. One patient had stable disease after three months, and therapy is also ongoing. So far, no severe adverse effects have occurred. Our cases confirm previous reports demonstrating a clinical effect and tolerability of PD-1 checkpoint inhibitors for heavily pre-treated patients with metastatic CSCC. Commercially available PD-1 checkpoint inhibitors may be useful in these patients who should be considered for PD-1 checkpoint inhibitor therapy, preferentially within clinical trials.
Keywords: PD1 checkpoint inhibitor; nivolumab; off-label; skin cancer.