The risks (i.e. exacerbation of preexisting MG with potential lethal outcome) and benefits (i.e. life-threatening metastatic MCC with a response rate of around 60% to PD-1/PD-L1 inhibitors) of PD-1/PD-L1 inhibitor therapy was discussed thoroughly with our neuromuscular specialists and the patient. Here, PDCD1 is linked to myasthenia gravis.