- In this phase I study, the maximum tolerated dose of imetelstat will be determined using a rolling 6 design where a minimum of 2 evaluable patients will be entered at each of 4 dose levels, where imetelstat is administered intravenously over two hours on Day 1 and 8 of a 21-day cycle in children with recurrent or refractory solid tumors, for up to 17 cycles, up to a total duration of therapy of 18 cycles (approximately 12 months).