Phase I/II Trial: Engineered Donor Graft (Orca Q) for Pediatric Hematopoietic Cell Transplant (HCT)

Primary graft failure

Evaluate primary graft failure through day +28, defined as being alive without recovery of neutrophils (achieving an absolute neutrophil count \>500/µL for 3 consecutive days) by day +28

Secondary graft failure

Evaluate secondary graft failure through day +100, defined as neutrophil engraftment followed by subsequent decline in absolute neutrophil counts to \<500 µL, unresponsive to growth factor therapy and in the absence of alternative explanations such as recurrence of the underlying malignant disorder, infections, microangiopathy, medications causing bone marrow suppression or immune-mediated cytopenia.

Non-relapse mortality (12 months post-transplant)

Evaluate non-relapse mortality, defined as death without evidence of disease recurrence, at 12 months post-transplant

Non-relapse mortality (24 months post-transplant)

Evaluate non-relapse mortality, defined as death without evidence of disease recurrence, at 24 months post-transplant.

Overall survival

Determine the overall survival at 24 months post-transplant, as defined as the time from the date of transplant to the date of death from any cause or, for surviving patients, to the date of last follow-up.

Relapse rate (12 months post-transplant)

Determine the relapse rate, as defined as the incidence of disease relapse through 12 months post-transplant. Disease relapse is defined as any of the following: ≥ 5% blasts in the bone marrow or peripheral blood, reappearance of pre-transplant cytogenetic abnormality, new evidence or redevelopment of extramedullary disease. Institution of any therapy to treat relapsed disease, such as withdrawal of immunosuppression or donor lymphocyte infusion (DLI), will be considered evidence of relapse regardless of whether any of these are met.