The use of unrelated cord blood (UCB) as a source for allogeneic hematopoietic stem cell transplantation (allo-HSCT) may result in comparable effects as using a human leukocyte antigen (HLA)-matched sibling donor (MS) among adult patients with B-cell acute lymphoblastic leukemia (B-ALL), according to a retrospective study published in the journal Stem Cell Research & Therapy.

Although MS donors are the preferred source for allo-HSCT, UCB is a known alternative. However, there are few studies that have evaluated the outcomes of adult patients with B-ALL who received an allo-HSCT with UCB.

This single-center, retrospective study evaluated data from 156 adult patients with B-ALL who underwent an allo-HSCT between 2006 and 2020. All patients were in complete remission prior to their transplant.

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At the time of transplant, the median age was 25 in the UCB group and 34 in the MS group (P =.002). Conditioning regimens were similar between the groups with the majority of patients receiving busulfan plus cyclophosphamide or total body irradiation plus cyclophosphamide.

Patients who underwent an MS allo-HSCT demonstrated a faster hematopoietic recover than patients whose transplant used UCB. There were 96.5% of patients in the UCB group and 100% in the MS group who achieved neutrophil engraftment by day 42 (P <.001), with a median time to engraftment of 18 and 11 days, respectively. Platelet engraftment occurred among 86.3% and 100% of patients in the UCB and MS groups, respectively (P <.001) in a median of 38.5 and 14 days, respectively.

Overall survival was similar between the groups during the first 700 days (P =.842), but was longer after 700 days among patients whose transplant used UCB (hazard ratio, 7.40; 95% CI, 1.12-48.93; P =.04). Other factors associated with longer survival after 700 days included first compete response and use of a busulfan-containing conditioning regimen.

The 2-year cumulative incidence of non-relapse-related mortality was 18.7% in the UCB group compared with 16.3% in the MS group (P =.67). The cumulative incidence of relapse at 2 years was 17.0% and 23.8% in the UCB and MS groups, respectively (P =.35). The 5-year disease-free survival (P =.82) and 5-year graft vs host disease (GVHD)-free relapse-free survival (P =.99) were also similar regardless of donor source.

Acute GVHD occurred more frequently in the UCB group compared with the MS group, with 28.3% and 2.3% of patients, respectively, developing grade II-IV disease (P <.001). There were 14.2% of patients in the UCB group and 2.3% in the MS group who developed grade III-IV acute GVHD (P =.03). However, the 2-year cumulative incidence of extensive chronic GVHD was more common in the MS group, affecting 35.3% of patients compared with 8.0% in the UCB group (P <.001).

“Our study shows that when treating adult B-ALL patients in complete response, UCB transplant can achieve comparable effects as MS transplant, may provide superior overall survival for patients with long-term survival, and should be considered a good alternative,” the authors concluded in their report.


Sun G, Tang B, Song K, et al. Unrelated cord blood transplantation vs. HLA‑matched sibling transplantation for adults with B‑cell acute lymphoblastic leukemia in complete remission: superior OS for patients with long‑term survival. Stem Cell Res Ther. 2022;13:500. doi: 10.1186/s13287-022-03186-3