TI was defined as a weighted average Hb >= 9 g/dL without any pRBC transfusions for a continuous period of >= 12 months at any time during the study after GMCN-508A Drug Product infusion. Time from drug product infusion to initial achievement of TI was calculated as the time from drug product infusion to the first Hb at which a participant can be declared as TI.

The weighted average Hb is an average area under the curve during the period of TI, from the start of TI when the Hb is first >= 9 g/dL with no transfusions in the preceding 60 days to the last available Hb at which the TI criteria are still met.

Annualized number of pRBC transfusions from 12 months post-drug product infusion through Month 24 compared to the annualized number of transfusions during the 24 months prior to enrollment.

Annualized volume of pRBC transfusions from 12 months post-drug product infusion through Month 24 compared to the annualized volume of transfusions during the 24 months prior to enrollment.

Time to neutrophil engraftment was defined as the time to the first of 3 consecutive absolute neutrophil count (ANC) >= 0.5 × 10^9/L obtained on different days after a post-transplant value of < 0.5 × 10^9/L. The Day of neutrophil engraftment is the first day of the 3 consecutive measurements, where Day 0 is the day of drug product infusion.

Platelet engraftment was defined as achieving 3 consecutive platelet values >= 20 × 10^9/L on different days after a post-transplant value of < 20 × 10^9/L, while no platelet transfusions administered for 7 days immediately preceding and during the evaluation period.

Platelet engraftment was defined as achieving 3 consecutive platelet values >= 20 × 10^9/L on different days after a post-transplant value of < 20 × 10^9/L, while no platelet transfusions administered for 7 days immediately preceding and during the evaluation period.

PedsQL GCS is designed to measure health-related quality of life in pediatric participants and adolescents (2 to 18 years of age). It encompasses 4 dimensions of functioning (physical [8 items], emotional [5 items], social [5 items], school [3 items]). Age groups: Toddler (2-4 years), Young pediatric (5-7 years), Pediatric (8-12 years), and Teens (13-18 years). Depending on the participant's age, the questionnaire may be completed by parent/caregiver as appropriate. For the Toddler group, the PedsQL GCS consist of 21 items, using a 5-point Likert scale (0 to 4); for all other groups, the PedsQL GCS consist of 23 items, with a 3-point Likert scale (0, 2, 4) for the young pediatric, and a 5-point Likert scale for the pediatric and teens groups. Scores are transformed on a scale from 0 to 100 where 0=100, 1=75, 2=50, 3=25, and 4=0. Higher scores indicate improved quality of life.

SF-36 is a generic quality-of-life instrument that had been widely used to assess HRQL of participants. Generic instruments were used in general populations to assess a wide range of domains applicable to a variety of health states, conditions, and diseases. The SF-36 consisted of 36 items that were aggregated into 8 multi-item scales (physical functioning [1=yes, limited a lot to 3=no, not limited at all], role-physical [1=all of the time to 5=none of the time], bodily pain [1=very severe to 6=none], general health [1=poor to 5=excellent], vitality [1=none of the time to 5=all of the time], social functioning [1=all of the time: to 5=none of the time], role emotional [1=all of the time to 5=none of the time] and mental health [1=all of the time to 5=none of the time]), with scores ranged from 0 to 100. Higher scores indicating better HRQL.

Neutrophil engraftment was defined as achieving 3 consecutive absolute neutrophil count (ANC) >= 0.5 × 10^9/L on different days after a post-transplant value of < 0.5 × 10^9/L within 42 days after drug product infusion.

Transplant-related mortality was determined by the investigator (any deaths considered related to the transplant.)

An AE was defined as any unfavorable and unintended sign (including abnormal laboratory findings), symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. A SAE was any AE, occurring at any dose and regardless of causality that: results in death, was life-threatening, required in-patient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect.

Overall survival was defined as time from date of GMCN-508A Drug Product infusion (Day 0) to date of death. Overall survival was censored at the date of last visit if the participant was still alive. Percentage of participants who survived throughout the study were reported.

acute and/or chronic graft-versus-host disease (GVHD) was determined by the investigator.