atezolizumab + tiragolumab + cisplatin + gemcitabine

This is a combination regimen consisting of four agents: - **Atezolizumab** is a monoclonal antibody immune checkpoint inhibitor targeting **programmed death-ligand 1 (PD-L1)**, designed to enhance the body’s immune response against tumor cells by preventing PD-L1–mediated inhibition of T-cell activation[4]. - **Tiragolumab** is an anti-TIGIT monoclonal antibody that blocks **TIGIT** (T cell immunoreceptor with Ig and ITIM domains), another immune checkpoint, thereby further augmenting antitumor immunity by promoting T-cell and natural killer cell activity[1][4]. - **Cisplatin** is a platinum-based chemotherapeutic that forms DNA crosslinks, resulting in inhibition of DNA synthesis and function, thus inducing apoptosis in rapidly dividing cancer cells[6]. - **Gemcitabine** is a nucleoside analog and antimetabolite that is incorporated into DNA, causing chain termination and apoptosis; it is often used in combination with cisplatin for synergistic cytotoxic effects in various cancers including lung, bladder, and biliary tract cancers[3][6]. This four-drug combination is under clinical investigation for various advanced and metastatic solid tumors, including non-small cell lung cancer, using immunotherapy (atezolizumab and tiragolumab) with cytotoxic chemotherapy (cisplatin and gemcitabine); it aims to leverage immunogenic cell death and enhance immune checkpoint blockade efficacy.