RP2D was determined by a traditional 3+3 dose escalation design, with the following restrictions: only doses of 60, 90, 120, and 150 mg/m^2 were explored, and escalation to 150 mg/m^2 would only occur if the 120 mg/m^2 dose was deemed safe and pharmacokinetic data indicate subtherapeutic exposure as compared with adults. The first cohort was administered bendamustine at the 90 mg/m^2 dose; de-escalation to the 60 mg/m^2 dose would only occur if the starting dose led to dose-limiting toxicity (DLT) in 2 or more participants. A DLT was defined as any study drug-related nonhematologic adverse event (AE) that was grade 4 for toxicity by National Cancer Institute's Common Toxicity Criteria for AEs, version 4. In addition, grade 3 or above allergic reaction or skin rash were considered DLTs. Hematologic AEs were not considered DLTs. The dose level at which at least 2 of 3 or 2 of 6 participants had a DLT was considered as exceeding the RP2D. The RP2D was the dose 1 step below that level.

All participants enrolled in Phase 1 of the study.

ORR was calculated as follows: number of participants in the primary analysis set achieving a best overall response of complete remission without platelet recovery (CRp) or complete remission (CR), divided by the number of participants in the primary analysis set. The most positive response for each patient during the study was counted. The 95% CI was calculated using binomial parameter exact method. Response was determined by the investigator, and evaluated per Jeha et al, 2006: A CR required no evidence of circulating blasts or extramedullary disease, an M1 marrow (≤ 5% bone marrow blasts), and recovery of peripheral counts (platelets ≥ 100 × 10^9/L and absolute neutrophil count ≥ 1.0 × 10^9/L). A CR without platelet recovery (CRp) required all of the criteria for a CR with the exception of platelet recovery.

The primary analysis set for efficacy included all participants treated at the RP2D in Phase 2.

Biological activity of bendamustine was defined as achieving a best response of partial response (PR), CRp, or CR. Rate was calculated as follows: number of participants in the primary analysis set achieving a best overall response of PR, CRp, or CR, divided by the number of participants in the primary analysis set. The most positive response for each patient during the study was counted. The 95% CI was calculated using binomial parameter exact method. Response was determined by the investigator, and evaluated per Jeha et al, 2006: A PR had to meet the following criteria: complete disappearance of circulating blasts and an M2 marrow (≥ 5% and ≤ 25% bone marrow blasts) and appearance of normal progenitor cells or an M1 marrow that did not qualify for CR or CRp. See Outcome Measure 2 for full definitions for CRp and CR.

The primary analysis set for efficacy included all participants treated at the RP2D in Phase 2.

Biological activity of bendamustine was defined as achieving a best response of partial response (PR), CRp, or CR. Rate was calculated as follows: number of participants in the primary analysis set achieving a best overall response of PR, CRp, or CR, divided by the number of participants in the primary analysis set. The most positive response for each patient during the study was counted. The 95% CI was calculated using binomial parameter exact method. Response was determined by the investigator, and evaluated per Jeha et al, 2006: A PR had to meet the following criteria: complete disappearance of circulating blasts and an M2 marrow (≥ 5% and ≤ 25% bone marrow blasts) and appearance of normal progenitor cells or an M1 marrow that did not qualify for CR or CRp. See Outcome Measure 2 for full definitions for CRp and CR.

The safety analysis set included all participants treated at any dose of bendamustine.

DOR was determined for the participants with CR or CRp in the primary analysis set, defined as the time from first achieving remission to the time when progression was diagnosed, the participant died, or the participant started receiving new antineoplastic therapy. Data from participants who do not progress were censored at the last valid assessments. Median DOR and its 95% confidence interval was determined based on the Kaplan-Meier method. Data from participants who received a transplant were censored at the time of the transplant.

No duration of remission (defined as CR or CRp) analysis was performed for participants in the primary analysis since none achieved remission.

The pharmacokinetic analysis set included all participants who were in the safety analysis set (ie, those treated at any dose of bendamustine) who had valid pharmacokinetic data; n=number of participants with valid data for this assessment.

The pharmacokinetic analysis set included all participants who were in the safety analysis set (ie, those treated at any dose of bendamustine) who had valid pharmacokinetic data; n=number of participants with valid data for this assessment.

The pharmacokinetic analysis set included all participants who were in the safety analysis set (ie, those treated at any dose of bendamustine) who had valid pharmacokinetic data; n=number of participants with valid data for this assessment.

The pharmacokinetic analysis set included all participants who were in the safety analysis set (ie, those treated at any dose of bendamustine) who had valid pharmacokinetic data; n=number of participants with valid data for this assessment.