Haploidentical Stem Cell Transplantation With Dual Source of Cells and Post-Transplant Cyclophosphamide

Dual sources of cells (DSC) with peripheral blood stem cell apheresis (PBSC) and surgical bone marrow (BM) for haploidentical hematopoietic cell transplantation (Hid-HCT) are used in China and some Asian countries. The experience of the Baltimore group for haploidentical transplant with post-transplant cyclophosphamide (PT-Cy) and reduced-intensity-conditioning (RIC) regimen used BM as a source of hematopoietic stem cells.

We retrospectively analyzed 64 Hid-HCT with DSC and PT-Cy, RIC (n = 57), or myeloablative-conditioning (MAC) (n = 7), from two public health Brazilian centers, with a median follow-up of 23.3 months (6.7-45.4).

The 49 malignant patients were 27/46 (58.7%) beyond the first remission or with no complete response, and three patients did not complete disease status evaluation before transplant. Eight of 62 patients (12.9%) had grade 2 or more Hematopoietic Cell Transplantation-Specific Comorbidity Index (HCT-CI), and two patients had no HCT-CI classified. Cytomegalovirus (CMV) viremia occurred in 26 of 57 (45.6%). The cumulative incidence of 100-day grade III-IV acute GVHD was 12.3% (7/57), with a 95% confidence interval (CI) of 3.8% and 20.8%, and 2-year moderate or severe chronic GVHD was 21.1% (11/52; 95% CI, 10.1%-32.3%). The 2-year relapses were 24.5% for malignant disease (12/49; 95% CI, 12.4%-36.5%). The 2-year overall survival (OS) probability was 54.7% (35/64; 95% CI, 42.5%-66.9%). Benign diseases achieve 2-year OS in 73.3% (11/15; 95% CI, 51%-95.7%) of the patients. The HCT-CI were significant in multivariate analyses for DFS (p = 0.002) and OS in uni- and multivariate analyses (both p < 0.001). The number of CD34⁺ cells by apheresis collection was significant in multivariate analysis for DFS (p = 0.039).

Hid-HCT using PT-Cy, DSC, and RIC is a safe option for benign and malignant diseases.