This is a single-arm, early safety and feasibility exploratory study to evaluate the efficacy and safety of MegaLT Injection in promoting platelet recovery after umbilical cord blood transplantation. Adults with malignant hematologic diseases who undergo umbilical cord blood transplantation will receive a single intravenous infusion of MegaLT Injection on day 14 after transplantation. Two dose levels will be evaluated sequentially, and platelet recovery, platelet transfusion requirements, and safety outcomes will be assessed.
This study is designed as a single-arm, early safety and feasibility exploratory study of MegaLT Injection in patients undergoing umbilical cord blood transplantation. Eligible participants will receive MegaLT Injection by intravenous infusion on day 14 after transplantation. The study includes two sequential dose levels: 1×10\^6/kg and 2.5×10\^6/kg. Three participants are planned for each dose level, with a total planned enrollment of 7 participants after accounting for an approximately 10% dropout rate. The study will evaluate platelet engraftment, platelet recovery, platelet transfusion requirements, hematopoietic recovery, and safety outcomes including adverse events, bleeding events, thromboembolic events, graft-versus-host disease, and transplant-related mortality.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
7
MegaLT Injection is prepared from eligible umbilical cord blood cells through directed expansion and quality control to obtain a megakaryocyte cell product. Participants will receive MegaLT Injection by intravenous infusion on day 14 after umbilical cord blood transplantation. The assigned dose will be 1×10\^6/kg or 2.5×10\^6/kg, with sequential dose escalation from the low-dose level to the high-dose level. Each participant will receive one assigned cell dose; multiple infusions may be considered if necessary according to the protocol.
Time to Platelet Engraftment
Platelet engraftment is defined as the first day of 7 consecutive days with platelet count ≥20×10\^9/L without platelet transfusion.
Time frame: From umbilical cord blood transplantation until documented platelet engraftment or the participant's last platelet assessment, assessed up to 6 months following MegaLT infusion.
Platelet Engraftment by Day 28
Cumulative incidence of platelet engraftment by day 28 after transplantation, defined as 7 consecutive days with platelet count ≥20×10\^9/L without platelet transfusion.
Time frame: At day 28 after umbilical cord blood transplantation
Platelet Recovery by Day 28
Cumulative rate of platelet recovery by day 28 after transplantation, defined as platelet count ≥50×10\^9/L for 7 consecutive days without platelet transfusion.
Time frame: At day 28 after umbilical cord blood transplantation
Time to Platelet Count Thresholds
Median time to achieve platelet counts of ≥20×10\^9/L, ≥50×10\^9/L, and ≥100×10\^9/L without platelet transfusion.
Time frame: From umbilical cord blood transplantation until documented platelet count recovery at each threshold or the participant's last platelet assessment, assessed up to 6 months following MegaLT infusion.
Platelet Transfusion Volume
Total amount of platelet transfusion received by participants within 4 weeks after MegaLT Injection.
Time frame: From MegaLT Injection to 4 weeks after injection
Neutrophil Engraftment by Day 28
Cumulative incidence of neutrophil engraftment by day 28 after transplantation, defined as an absolute neutrophil count ≥0.5×10\^9/L for 3 consecutive days.
Time frame: At day 28 after umbilical cord blood transplantation
Megakaryocyte Level in Bone Marrow
Megakaryocyte level assessed by bone marrow smear 4 weeks after MegaLT Injection.
Time frame: At 4 weeks after MegaLT Injection
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