US Study of ECT-001-CB in Pediatric and Young Adult Patients With High-Risk Myeloid Malignancies

Cord blood (CB) transplants are an option for patients lacking an HLA identical donor but are hampered by low cell dose, prolonged aplasia and high transplant related mortality. UM171, a novel and potent agonist of hematopoietic stem cell self renewal could solve this major limitation, allowing for CB's important qualities as lower risk of chronic GVHD and relapse to prevail. In previous trials (NCT02668315, NCT03913026, NCT04103879, and NCT03441958), the CB expansion protocol using the ECT-001-CB technology (UM171 molecule) has proven to be technically feasible and safe in adults. UM171 expanded CB was associated with a prompt (D+17), robust (98%) and durable neutrophil recovery. Amongst patients who received a single UM171 CB transplant with a median follow-up of 18 months, risk of TRM (10%), grade 3-4 acute GVHD (13%) and moderate-severe chronic GVHD (2%) was low at 1 year post-transplant. Incidence of severe viral and bacterial infections was reduced and immunosuppression could be discontinued in 77% of patients at 1 year. Thus, PFS and GRFS were very promising, 72% and 59% at 12 months, 69% and 53% at 24 months, respectively, in particular accounting for a large proportion of very high-risk patients. By a 10-fold increase of CB accessibility, ECT-001-CB allowed access to smaller, better HLA matched CBs. This new study seeks to test a similar strategy in a group of pediatric and young adult patients with high risk myeloid malignancies. 12 patients will be enrolled in the first stage of this 2-stage design protocol. If intervention is considered promising (\<= 3 relapses in the first 12 patients), this study will open multicenter and be extended to a second stage (16 additional patients for a total accrual 28).