A phase 2 clinical trial has demonstrated exceptional efficacy outcomes for unrelated umbilical cord blood transplantation (UCBT) in treating patients with hematologic malignancies, according to results presented at the 2025 Tandem Meeting.
The study, conducted under trial identifier NCT00719888, showed impressive survival rates across a diverse patient population. Among the 132 participants, researchers observed a two-year overall survival rate of 74% (95% CI, 65%-80%) and a progression-free survival rate of 70% (95% CI, 61%-77%). The study also reported encouragingly low rates of relapse at 16% and non-relapse mortality at 14%.
Superior Outcomes in Pediatric Patients
Particularly noteworthy were the results in pediatric patients, where the treatment showed even greater efficacy. The 71 pediatric recipients demonstrated a two-year overall survival rate of 81% (95% CI, 69%-89%) and a progression-free survival rate of 78% (65%-86%). These young patients also experienced lower complications, with relapse and non-relapse mortality rates of 13% and 9%, respectively.
Breakthrough for MRD-Positive Patients
A significant finding emerged regarding patients with minimal residual disease (MRD)-positive acute leukemia. The study revealed that UCBT maintained strong efficacy in this traditionally challenging-to-treat population, with two-year overall survival reaching 67% (95% CI, 46%-81%). Most notably, these patients experienced a remarkably low relapse rate of just 11%.
"This study confirms, prospectively, that in contrast to other stem-cell sources, UCBT demonstrates low rates of relapse in patients with acute leukemia with MRD coming into transplant," stated Dr. John Colgan, a pediatric bone marrow transplant fellow at Fred Hutchinson Cancer Center.
Treatment Protocol and Patient Demographics
The trial implemented two conditioning regimens: high-intensity and intermediate-intensity. The majority of patients (79%) received the high-intensity protocol, which included fludarabine, cyclophosphamide, and total body irradiation. The patient population had a median age of 20 years and included individuals with various hematologic malignancies:
- 43% with acute myeloid leukemia (AML)
- 36% with acute lymphocytic leukemia (ALL)
- 7% with myelodysplastic syndromes (MDS)
Clinical Implications
These results represent a significant advancement in blood cancer treatment, particularly for patients with residual disease. The study's findings suggest that umbilical cord blood may offer unique advantages as a donor source for transplantation in hematologic malignancies, potentially changing treatment approaches for specific patient populations.
