Namitecan is a potent topoisomerase I inhibitor, with antitumor property. In Vitro: Namitecan and cetuximab cooperate in inhibiting EGFR expression. Namitecan induces a dose-dependent decrease in EGFR expression in the different cell lines^[1]. ST1968 induces a comparable level of apoptosis in A431 and A431/TPT cells with IC₅₀ of 0.21 and 0.29 μM^[2]. In Vivo: Namitecan (10 mg/kg) in combination with cetuximab (1 mg/mouse) induces synergistic antitumor effects in SCC models as a function of EGFR gene copy number^[1]. ST1968 (25 mg/kg) causes acceptable body weight loss and no toxic deaths. ST1968 produces a 100% complete response rate in the mice bearing the A431 tumor, and retains a relevant activity in the topotecan-resistant tumor^[2].