92 Background: E is a new marine compound with broad in vitro/in vivo antitumor activity. Low μM concentrations lead to cell-death through membrane permeabilization. E has shown evidence of activity in pre-treated GE patients (pts) in phase I trials. Methods: The primary objective was to determine the tolerability and efficacy of E in pts with GE cancer after 1-2 prior chemotherapy (CT) lines. Initially, dose was optimized (Phase Ib) in two different schedules: a fixed flat dose (FD) of intravenous (i.v) E (8 and 10 mg), in 24h, biweekly (Arm A) and i.v E (3.0 and 3.75mg), in 3h, weekly (Arm B). After dose optimization patients were included and stratified by histology to each optimal dose (Phase II) to determine the rate of progression-free survival at week 16 ± 1 (PFS4) in an intention to treat analysis. If at least two out of 15 pts reached PFS4, recruitment would continue to a maximum of 40 pts per arm. Results: A total of 45 pts were recruited, 12 pts into Phase Ib (Arm A/B: 6/6 pts) and 33 pts into ...