gemcitabine + erlotinib + S-1

The combination of gemcitabine, erlotinib, and S-1 (often referred to as the GTS regimen) is an investigational chemotherapy protocol for advanced pancreatic cancer. Gemcitabine is a nucleoside analog that inhibits DNA synthesis, leading to cell death. Erlotinib is a small molecule inhibitor targeting the epidermal growth factor receptor (EGFR) tyrosine kinase, thereby blocking downstream signaling pathways involved in tumor proliferation and survival. S-1 is an oral fluoropyrimidine derivative composed of tegafur (a prodrug of 5-fluorouracil), gimeracil (an inhibitor of dihydropyrimidine dehydrogenase), and oteracil potassium (which reduces gastrointestinal toxicity). The combination aims to enhance antitumor efficacy by attacking cancer cells through multiple mechanisms: direct cytotoxicity from gemcitabine and S-1, plus inhibition of EGFR-mediated signaling by erlotinib. This regimen has shown modest clinical benefit with acceptable toxicity in phase II studies for patients with locally advanced or metastatic pancreatic adenocarcinoma[1][2][4].

Other names

GTS regimen