Deceleration in the rate of keratinocyte cancers and pre-cancerous lesions during PD-1 inhibition for advanced melanoma, with recrudescence on discontinuation.

Immune checkpoint inhibition has revolutionised the treatment of many cancer subtypes. PD-1 inhibition typically results in T-cell activation via immune activation rather than by directly targeting tumour cells1 . We present 3 patients treated with pembrolizumab for advanced melanoma, noted to have a significant deceleration in the rate of development of keratinocyte cancers, pre-cancerous lesions and improvement in field cancerisation during PD-1 inhibition; 1 patient demonstrated a significant recrudescence on discontinuation of therapy.