Anti-PD-1 Therapy Leads to Near-Complete Remission in a Patient with Metastatic Basal Cell Carcinoma.

BACKGROUND: Metastatic basal cell carcinoma is rare and the prognosis is poor, with a lack of established treatment options for patients progressing on or after treatment with inhibitors of the hedgehog signaling pathway. CASE REPORT: A man with pulmonary metastases of a basal cell carcinoma progressing after treatment with sonidegib and vismodegib was started on treatment with the anti-PD-1 antibody pembrolizumab. Upon treatment, rapid clinical improvement occurred, and after 5 cycles, the computed tomography scan showed near-complete remission of all tumor lesions. The tumor cells showed the absence of PD-L1 expression. DISCUSSION: We report the first case of a patient with metastatic basal cell carcinoma experiencing an exceptional response to treatment with pembrolizumab in the absence of PD-L1 expression on the tumor cells. Immune checkpoint inhibition seems a promising treatment strategy for metastatic basal cell carcinoma. Our case suggests that the lack of PD-L1 expression does not rule out potential benefit from checkpoint inhibitor treatment.