The interaction between Programmed cell Death 1 (PD-1), expressed on T cells and tumour expressed PD-L1down-regulates T cell activation to create immune tolerance and avoid autoimmunity. Immunotherapies such as anti-PD1 are emerging as a new treatment option in patients with metastatic cancers, and studies have demonstrated durable benefits in patients with advanced solid tumours.1,2 To date, cutaneous adverse reactions of anti-PD1 are poorly described.
We aimed to describe the cutaneous manifestations of the anti-PD1 use in oncodermatology patients.
Following an ethical approval, 71 patients with metastatic melanoma, lung, renal cell and prostate cancer on anti-PD1 monotherapy between 1/May/2012 to 1/February/2015 in Westmead Hospital, Sydney were identified as eligible for the study. Of these patients, 39 patients were referred to the dermatology department for assessment. Kaplan-Meier curves were used to estimate the distribution of time from treatment commencement to development of cutaneous lesions.
Of the 39 patients reviewed, 35 patients developed new cutaneous lesions after anti-PD1 commencement. Most frequently observed cutaneous lesions were immune related such as lichenoid reactions (44%), eczema (41%) and vitiligo (28%). The median number of days from commencement of treatment to developing a lichenoid reaction was 426 days (SE 134 days), to eczema was 467 days (SE 129 days), and to vitiligo was more than 600 days. Thirty patients (77%) developed at least one of three above immune related cutaneous manifestation. There was no association between the development of these three toxicities, with the observed numbers of patients with each combination of lichenoid, eczema and vitiligo similar to those expected if these lesions occurred independently (chi-squared test of independence P=0.894).
Less commonly observed lesions include actinic keratosis (28%), folliculitis (13%), new naevus (18%), and cutaneous squamous cell carcinoma (10%).
Immune related cutaneous manifestations such as lichenoid reactions, eczema and vitiligo were commonly observed in our cohort.