The thrombopoietin (TPO) receptor agonist romiplostim N01 supported platelet engraftment and recovery in patients with hematologic malignancies who underwent unrelated umbilical cord blood transplant (UCBT), according to interim findings from a single-center, single-arm phase 2 trial (NCT06693791) presented at the
As of February 25, 2026, platelet engraftment, defined as a platelet count of at least 20 × 10⁹/L for 7 consecutive days without transfusion, was achieved in 27 of 29 evaluable patients at a median of 35 days (range, 25-74). The cumulative incidence of platelet engraftment was 24.1% by day 28 (95% CI, 12.3%-44.1%) and 89.7% by day 60 (95% CI, 75.7%-97.4%). Neutrophil engraftment occurred at a median of 16 days (range, 12-25), with a cumulative rate of 100% by day 28.
“[Based on] this interim analysis, romiplostim N01 may promote platelet engraftment and recovery after unrelated UCBT, with no treatment-related serious adverse effects [(AEs) observed],” lead study author Wanjie Wang, MD, of the Department of Hematology at the The First Affiliated Hospital of University of Science and Technology of China, and the Division of Life Sciences and Medicine at University of Science and Technology of China in Hefei, and colleagues wrote in a poster presentation of the data.
The single-center, single-arm phase 2 trial enrolled adults with hematologic malignancies who had undergone UCBT, with a target enrollment of 34 patients between December 2024 and December 2026.1,2 Delayed hematopoietic recovery, particularly platelet recovery, remains a major limitation of unrelated UCBT because of the limited graft cell dose, and prospective clinical data on TPO receptor agonists in this setting are limited.1
Romiplostim N01 was administered for 4 doses at 5 µg/kg, initiated between day 1 and day 28 after UCBT. The primary end points were time to platelet engraftment and the cumulative platelet engraftment rate by day 28. Secondary end points included time to platelet recovery, achievement of a platelet count of at least 100 × 10⁹/L after stopping transfusions, total platelet transfusion volume within 4 weeks, cumulative neutrophil engraftment by day 28, bone marrow megakaryocyte counts at week 4, and safety.
As of the data cutoff, 30 patients had been enrolled; 1 withdrew after the first dose because of liver function impairment, leaving 29 evaluable patients.
The median age of evaluable patients was 37 years (range, 18-57), and 48% of patients were female. Diagnoses included acute myeloid leukemia (n = 14), acute lymphoblastic leukemia (n = 10), myelodysplastic syndromes (n = 3), mixed-phenotype acute leukemia (n = 1), and extranodal natural killer/T-cell lymphoma (n = 1). All patients received myeloablative conditioning and grafts that were at least 6/10 HLA-matched. Median infused doses were 2.04 × 10⁷/kg for total nucleated cells (range, 0.61-9.40) and 1.78 × 10⁵/kg for CD34-positive cells (range, 0.65-3.90).
Platelet recovery, defined as a platelet count of at least 50 × 10⁹/L for 7 consecutive days without transfusion, occurred in 24 patients at a median of 42.5 days (range, 18-141). Twenty-one patients reached a platelet count of at least 100 × 10⁹/L at a median of 52 days (range, 33-314). The median platelet transfusion requirement was 8 units (range, 4-19).
No serious treatment-related AEs were observed in the interim analysis, including grade II to IV acute graft-vs-host disease that occurred in 7 of 29 patients (24.1%), cytomegalovirus infection in 13 of 29 patients (44.8%), and hemorrhagic cystitis in 11 of 29 patients (37.9%).
