Abstract

Purpose In Asian countries, paclitaxel once per week is used as second-line treatment in advanced gastric cancer, including human epidermal growth factor receptor 2 (HER2) –positive tumors. The role of anti-HER2 agents, including lapatinib, in this setting and population is unclear. Patients and Methods TyTAN was a two-part, parallel-group, phase III study in Asian patients. An open-label, dose-optimization phase (n = 12) was followed by a randomized phase (n = 261), in which patients who were HER2 positive by fluorescence in situ hybridization (FISH) received lapatinib 1,500 mg once per day plus once-per-week paclitaxel 80 mg/m 2 or paclitaxel alone. The primary end point was overall survival (OS). Secondary end points included progression-free survival (PFS), time to progression (TTP), overall response rate (ORR), time to response, response duration, and safety. Analyses were based on immunohistochemistry (IHC) and gastrectomy status, prior trastuzumab therapy, and regional subpopulations. Results Median OS was 11.0 months with lapatinib plus paclitaxel versus 8.9 months with paclitaxel alone (P = .1044), with no significant difference in median PFS (5.4 v 4.4 months) or TTP (5.5 v 4.4 months). ORR was higher with lapatinib plus paclitaxel versus paclitaxel alone (odds ratio, 3.85; P < .001). Better efficacy with lapatinib plus paclitaxel was demonstrated in IHC3+ compared with IHC0/1+ and 2+ patients and in Chinese compared with Japanese patients. A similar proportion of patients experienced adverse events with each treatment (lapatinib plus paclitaxel, 100% v paclitaxel alone, 98%). Conclusion Lapatinib plus paclitaxel demonstrated activity in the second-line treatment of patients with HER2 FISH-positive IHC3+ advanced gastric cancer but did not significantly improve OS in the intent-to-treat population.