camrelizumab + gemcitabine + sintilimab + toripalimab

This appears to be a combination of four separate drugs: camrelizumab, gemcitabine, sintilimab, and toripalimab. Camrelizumab, sintilimab, and toripalimab are all PD-1 inhibitors (immune checkpoint inhibitors) that work by blocking the interaction between PD-1 and its ligands, enhancing T-cell responses against cancer cells. Gemcitabine is a chemotherapeutic agent. While combinations of PD-1 inhibitors with gemcitabine have been studied (particularly camrelizumab + gemcitabine + cisplatin and toripalimab + gemcitabine + cisplatin), there is no evidence in the provided information of all four drugs being used together as a single regimen.