This multicenter dose escalation study employed a standard 3+3 design. T was given as a 1-h infusion on day (D)1 with low dose I intravenously on D2 and 4 of a 21D cycle. Dose limiting toxicities (DLTs) were evaluated in cycle one. Eligibility required confirmed EWS::FLI1 fusion transcript...At DL 2 and above, there were 4 PRs, 6 SD in 14 evaluable pts (Table).