Haploidentical Stem Cell Transplantation Had a Lower Incidence of Bronchiolitis Obliterans Syndrome Compared with HLA-Matched Sibling Transplantation for Patients with Hematologic Malignancies: Benefit from ATG?

Background: Haploidenticalstem cell transplantation(HID-SCT) based on antithymocyte globulin (ATG) GVHD prophylaxis had achieved similar incidence of cGVHD with HLA-matched sibling transplantation (MSD-SCT). However, bronchiolitis obliterans syndrome (BOS) serve as pulmonary cGVDH, was rarely compared between HID and MSD transplantation.

Methods: One thousand four hundred and five patients with hematologic malignancies underwent SCT were enrolled in this retrospective study. Based on donor type, we divided the patients into three groups: HID, MSD and MUD (match unrelated donor) groups. All patients in HID and MUD group received ATG for GVHD prophylaxis, and the minority of patients in MSD group because of clinical trials. The vast majority of HID-SCT recipients transplanted with mixed grafts (bone marrow plus peripheral blood stem cell), whereas most MSD-SCT and all MUD-SCT recipients received PBSC (peripheral blood stem cell) grafts. The cumulative incidences and risk factors of BOS were analyzed.

Results: The 5-year cumulative incidence of BOS was 7.2% in the whole population. HID transplantation had lower 5-year cumulative incidence of BOS than MSD transplantation (4.1% vs 10.0%; p<0.001), and the similar incidence with MUD transplantation (4.1% vs 6.2%; p=0.224). The 5-year cumulative incidence of BOS was lower in ATG group than that in non-ATG group in the whole and MSD population both (4.6% vs 11.2%; p<0.001; and 4.1% vs 11.2%; p=0.042, respectively). The 5-year incidence of BOS in mixed grafts group was also lower than that in PBSC group (4.2% vs 9.1; p=0.001). Multivariate analysis showed that HID, ATG and mixed grafts were protective factors for BOS (OR 0.3; 95%CI, 0.2 to 0.6; p<0.001; OR 0.3; 95%CI, 0.2 to 0.7; p=0.001; OR 0.3; 95%CI, 0.1 to 0.8; p=0.013), and aGVHD and cGVHD were independent risk factors for BOS (OR 2.1; 95%, 1.1 to 4.3; p= 0.035; OR 10.1; 95%CI, 4.0 to 25.0; p<0.001).

Conclusions: HID transplantation had a lower incidence of BOS than MSD transplantation, which might be associated with ATG and mixed grafts.

No relevant conflicts of interest to declare.