This is an immunohistochemical study looking at variation in the expression of the programmed death-1 receptor (PD-1) and the programmed cell death ligand-1 (PD-L1), comparing cutaneous malignancies which invaded the orbit with uncomplicated nodular basal cell carcinomas. The authors retrospectively analysed 12 orbital exenteration specimens taken between 2008 and 2015, all for cutaneous neoplasms which invaded the orbit. They compared these with 10 specimens from age and sex-matched patients with nodular basal cell carcinomas (BCC). Paraffin-embedded tissue was processed to allow antigen retrieval and then incubated with antibodies against PD-1 and PD-L1. The exenteration specimens comprised five basal cell carcinomas, five squamous cell carcinomas, one sebaceous cell carcinoma and one undifferentiated carcinoma. All these showed significantly higher rates of expression of both PD-1 and PD-L1 compared with the nodular BCCs. PD-1 is expressed on T-and B-lymphocytes, monocytes and dendritic cells, and when it binds to PD-L1, leads to inactivation of these cells which is thought to reduce the immune system’s tumour surveillance ability. Anti-PD-1 drugs could potentially improve tumour control, and have been approved for some tumours. The authors suggest these may also be applicable to aggressive cutaneous malignancies with the hope of avoiding exenteration. The study is interesting but is weak due to small numbers and a mixture of carcinoma sub-types in the exenteration group.
PD-1 and PD-L1 in exenteration specimens
Reviewed by James Hsuan
Programed death-1 pathway in orbital invasion of cutaneous carcinomas.
