A case of metastatic basal cell carcinoma treated with continuous PD-1 inhibitor exposure even after subsequent initiation of radiotherapy and surgery

Advanced basal cell carcinomas (BCCs) resistant to Smoothened inhibitor (SI) therapy represent a treatment challenge.1 Recently, case reports showed that BCCs can be responsive to systemic immunotherapy,2-4 specifically programmed cell death protein-1 (PD-1) inhibitors. These cases are highly encouraging as salvage therapy after resistance to SI therapy. In 2 metastatic BCC cases, shrinkage of all lesions occurred, specifically lung lesions3 in one and liver lesions in the other.4 Currently, it is unknown whether metastatic BCC can exhibit differential response or resistance to PD-1 inhibitors.