Chimeric antigen receptor (CAR) T-cell therapy, which involves genetically altering a patient’s T-cells with viral vectors to express CAR constructs, expanding these newly engineered T-cells ex vivo, and reinfusing them into the patient so that they exert anti-tumor effects, may show promise in MCC patients refractory to PD-1/PD-L1 axis blockade [121]. The gene discussed is CD274; the disease is Merkel cell skin cancer.