Various types of ICIs are used to treat advanced BTC, including durvalumab, pembrolizumab, sintilimab, and nivolumab.[14] Sintilimab is a fully human, recombinant, IgG4-type anti-PD-1 monoclonal antibody that is effective against both adenocarcinoma and squamous cell carcinoma. Here, PDCD1 is linked to squamous cell carcinoma.