New anti cancer drug (Tigit Inhibitor) induced psoriasis

Background: Drug-related psoriasis is a cutaneous side effect of several drugs. Recently, there have been cases in which cutaneous adverse effects have been induced by a new anticancer drug. T cell immunoreceptor with immunoglobulin and immunoreceptor tyrosinebased inhibitory motif domains (TIGIT) is a new checkpoint receptor targets for cancer immunotherapy. MK-7684, an antagonistic agent targeting TIGIT, is on phase 1 trial for advanced solid tumors treatment from December, 2016. Observation: A 63-year-old male with non-small-cell lung cancer (NSCLC) had started pembrolizumab treatment. After nine months, he presented with erythematous scaly plaques on his elbows, thighs, knees and lower back. The skin lesion was mild and controlled by topical methylprednisolone. Four months later, pembrolizumab was discontinued and MK-7684 had been started. After one month, he developed multiple erythematous plaques with scales on his whole body. He also developed trachyonychia and yellow discoloration on his twenty nails. He denied past medical history of psoriasis. A skin biopsy revealed psoriasis. After the discontinuation of TIGIT inhibitor, new lesions have not appeared and the existing lesions have improved. Also, there was no psoriatic nail change on his newly growing nails. Key message: Herein, we present a case of psoriasis after TIGIT inhibitor treatment in a patient with NSCLC. We claim that clinicians should be aware of the potential development or aggravation of psoriasis when administrating TIGIT inhibitor treatment.