Umbilical Cord Blood Transplant Effective in Patients With Blood Cancer

Microscopic images of blood cells as a result of leukemia: © AkuAku - stock.adobe.com

Findings from a phase 2 study (NCT00719888) presented at the 2025 Tandem Meeting suggest that unrelated umbilical cord blood transplantation (UCBT) is effective for patients with hematologic malignancies following microcystic adnexal carcinoma (MAC).¹

Among patients who were treated on the study (n = 132), the 2-year overall survival (OS) rate was 74% (95% CI, 65%-80%) in this population, with a reported 2-year progression-free survival (PFS) rate of 70% (95% CI, 61%-77%). Furthermore, the 2-year relapse rate was 16% (95% CI, 10%-23%), and the non-relapse mortality (NRM) rate was 14% (95% CI, 9%-21%).

In pediatric patients who received UCBT (n = 71), greater benefits to 2-year OS and PFS were observed. The 2-year OS rate was 81% (95% CI, 69%-89%), and the 2-year PFS rate was 78% (65%-86%). Additionally, the 2-year relapse and NRM rates were 13% (95% CI, 6%-22%) and 9% (95% CI, 4%-18%), respectively.

Particular benefit was also observed in patients with acute leukemia and minimal residual disease (MRD)–positive status (n = 33) vs those with MRD-negative disease (n = 81). The 2-year OS and PFS estimates for patients with MRD-positive acute leukemia were 67% (95% CI, 46%-81%) and 63% (95% CI, 42%-78%), with 2-year relapse and NRM rates of 11% (95% CI, 3%-26%) and 26% (95% CI, 11%-43%).

The odds ratio (OR) for OS in the MRD-positive population vs the MRD-negative group was 2.10 (95% CI, 1.02-4.35; P = .04). ORs for PFS, relapse rate, and NRM rates were 1.79 (95% CI, 0.89-3.59; P = .10), 0.92 (95% CI, 0.31-2.78; P = .89), and 3.38 (95% CI, 1.27-9.03; P = .01), respectively.

“Data from this prospective trial demonstrated excellent outcomes for cord blood transplant recipients receiving myeloablative conditioning in both the high- and middle-intensity arms,” John Colgan, MD, a pediatric bone marrow transplant and immunotherapy fellow at Fred Hutchinson Cancer Center, said in the presentation.¹ “Critically, 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, consistent with evolving literature in the field. Overall, this study highlights the role of cord blood as a uniquely beneficial donor source in transplant for [patients with hematologic malignancies].”

The single-arm phase 2 study enrolled a total of 132 adult and pediatric patients with hematologic malignancies undergoing UCBT following MAC. Patients were assigned to either a high-intensity or intermediate-intensity regimen.

Patients undergoing the high-intensity regimen received 25 mg/m² of intravenous fludarabine over 30 minutes at 8 to 6 days before UCBT treatment and 60 mg/kg of intravenous cyclophosphamide over 30 minutes on days 6 and 7 before UCBT. Additionally, total body irradiation (TBI) at 165 cGy was administered twice daily at 4 to 1 days before UCBT.

Patients in the intermediate-intensity regimen arm received 30 mg/m² of intravenous fludarabine over 30 to 60 minutes on days 6 through 3 before UCBT treatment and over 30 minutes at 2 days before treatment. Additionally, 50 mg/kg of intravenous cyclophosphamide over 30 minutes was given on day 6 before treatment and 5 mg/kg of intravenous thiotepa over 2 to 4 hours at 4 to 5 days before initiation of UCBT. TBI was dosed at 200 cGY once daily at 2 to 1 days before UCBT.

Patients on trial had a median age of 20 years (range, 0-63) and had a median follow-up of 3.5 years (range, 0.2-16.2); 43% were female. A total of 43% of patients had acute myeloid leukemia (AML), 36% had acute lymphocytic leukemia (ALL), and 7% had myelodysplastic syndromes (MDS). A total of 29% of patients had MRD–positive acute leukemia, and 31% had CR2-positive status. Of note, 79% and 21% of patients were assigned to the high-intensity and intermediate-intensity regimens, respectively.

The primary study end point was 1-year survival. Secondary end points included transplant-related mortality (TRM) at 6 months, disease-free survival (DFS) at 1 and 2 years, relapse at 1 and 2 years, neutrophil engraftment at day 42, and platelet engraftment at 6 months.²

References

• Colgan J, Gooley TA, Hadland B, et al. Results from a prospective phase II clinical study: high vs medium-intensity regimens in patients undergoing cord blood transplantation. Presented at: 2025 Transplantation and Cellular Therapy Meetings; February 12-15, 2025; Honolulu, HI. Abstract 12
• Umbilical cord blood transplant, cyclophosphamide, fludarabine, and total-body irradiation in treating patients with hematologic disease. ClinicalTrials.gov. Updated January 5, 2025. Accessed February 13, 2025. https://tinyurl.com/7drpa7p7