Haploidentical peripheral blood stem cells combined with bone marrow or unrelated cord blood as grafts for haematological malignancies: an open-label, multicentre, randomised, phase 3 trial.

BACKGROUND

Retrospective studies suggested that haploidentical transplantation combined with unrelated cord blood might improve survival for patients with haematological malignancies. We aimed to assess whether transplantation of haploidentical peripheral blood stem cells (PBSCs) plus unrelated cord blood would achieve superior disease-free survival compared with transplantation of haploidentical PBSCs plus bone marrow in this population.

METHODS

We did an open-label, randomised, phase 3 trial at seven hospitals in China. Eligible patients (aged 18-65 years) had a diagnosis of haematological malignancy, an Eastern Cooperative Oncology Group performance status of 0-2 and transplant comorbidity index of 0-2, and were receiving their first allogenic haematopoietic stem cell transplant. Patients were randomly assigned (1:1) to receive transplantation of haploidentical PBSCs plus bone marrow or haploidentical PBSCs plus unrelated cord blood. The primary endpoint was 1-year disease-free survival. All efficacy and safety endpoints were assessed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT05290545) and is complete.

FINDINGS: Between March 5, 2022, and Jan 2, 2023, 357 participants were screened for eligibility, and 314 were randomly assigned to receive transplantation of haploidentical PBSCs plus unrelated cord blood (n=157) or haploidentical PBSCs plus bone marrow (n=157). Median follow-up was 17·2 months (IQR 10·0-20·8) after random assignment. 1-year disease-free survival was 82·2% (95% CI 75·2-87·3) in the group receiving haploidentical PBSCs plus unrelated cord blood (PBSCs plus unrelated cord blood group) and 65·6% (57·6-72·5) in the group receiving haploidentical PBSCs plus bone marrow ([PBSCs plus bone marrow group] hazard ratio [HR] 0·47, 95% CI 0·30-0·74; p=0·0010). The most common grade 3-5 adverse events within 100 days of transplantation in participants in the PBSCs plus unrelated cord blood and PBSCs plus bone marrow groups were infections (58 [37%] of 157 vs 77 [49%] of 157, p=0·030), acute graft-versus-host disease (49 [31%] vs 61 [39%]), and gastrointestinal disorders (38 [24%] vs 38 [24%]). Seven (4%) patients in the PBSCs plus unrelated cord blood group and 17 (11%) in the PBSCs plus bone marrow group died of transplantation-related causes within 100 days of transplantation. Causes of deaths in the PBSCs plus unrelated cord blood group versus the PBSCs plus bone marrow group included infections (four [3%] vs 11 [7%]), acute graft-versus-host disease (one [1%] vs three [2%]), vascular disorders (two [1%] vs one [1%]), cardiac disorders (none vs one [1%]), and respiratory disorders (none vs one [1%]).

INTERPRETATION: Transplantation of haploidentical PBSCs plus unrelated cord blood achieved superior 1-year disease-free survival compared with transplantation of haploidentical PBSCs plus bone marrow in patients with haematological malignancies, with a more satisfactory safety profile. Our results suggest that combining haploidentical PBSCs with unrelated cord blood, rather than with bone marrow, could be a better treatment option for this population.

FUNDING: None.