Karcinom Merklovih celic (KMC) je redek, agresiven nevroendokrini kožni rak s slabo prognozo, posebno, ko je v napredovalem stadiju. Incidenca na splošno narašča, čeprav podatki o incidenci kažejo na razlike med geografskimi področji. Med dejavnike tveganja štejemo starost, imunosupresijo in izpostavljenost ultravijoličnemu sevanju. Znana je povezava med MCC in okužbo s poliomavirusom, čeprav natančnega mehanizma, ki vodi v karcinogenezo, še ne razumemo v celoti. Pri lokalizirani bolezni je izbor zdravljenja kirurgija (ko je to mogoče), sledi mu dopolnilno obsevanje ali obsevanje v kombinaciji s kemoterapijo. Pri razsejani bolezni je bila doslej na voljo le kemoterapija, čeprav so dolgotrajni odgovori ob njej redki. Glede na to, da je onkogeneza tumorja povezana z integracijo poliomavirusa Merklovih celic in mutacijami, povzročenih z ultravijoličnim sevanjem, obstaja logična osnova za zdravljenje z imunoterapijo oz. protitelesi, ki ciljajo pot PD-L1/PD-1. Nedavno objavljene raziskave v prvem in drugem redu zdravljenja z inhibitorji imunskih stikal (anti-PD-1/PD-L1-protitelesi) kažejo obetajoče rezultate s sprejemljivim varnostnim profilom zdravljenja, zato tovrstno zdravljenje postaja standardno in je že priporočeno v mednarodnih smernicah za zdravljenje razsejanega raka Merklovih celic. Objavljeni podatki randomiziranih raziskav kažejo na obetajočo učinkovitost teh zdravil pri metastatski bolezni. Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine skin cancer with a poor prognosis in advanced stage. The incidence is increasing with some deviations between different geographic regions. The risk factors are advanced age, immunosuppression, and ultraviolet light exposure. There are associations between MCC and polyomavirus infection, but the exact mechanism that leads to carcinogenesis is yet to be fully understood. For localized disease (when feasible), surgery is the recommended treatment, followed by adjuvant radiation or chemoradiation. In the metastatic setting, chemotherapy has been the standard treatment, but durable responses are rare. As tumour oncogenesis is linked to Merkel cell polyomavirus integration and ultraviolet-radiation-induced mutations, there is rationale for treatment with immunotherapy antibodies that target the PD-L1/PD-1 pathway. However, recently published trials with immune checkpoint inhibitors in the first- and second-line showed promising results with a tolerable safety profile, and these are becoming the standard therapy, already included in international guidelines. The published data showed a high efficacy of avelumab in the metastatic setting.