Matched sibling donors aside, donor type was not associated with significant differences in overall survival in patients with myelofibrosis who underwent hematopoietic cell transplantation (HCT), according to study results published online ahead of print in Blood Advances.

“While matched sibling donors remain a superior donor option due to improved engraftment, there is no significant difference in HCT outcomes from haploidentical and matched unrelated donors,” wrote corresponding author Tania Jain, MBBS, of Johns Hopkins University, Baltimore, Maryland, and coauthors.

The study investigated the impact of donor type in 1597 patients from the Center for International Blood and Marrow Transplant Research registry who received HCT for myelofibrosis between 2013 and 2019. The study found that between 2013 and 2019, the number of haploidentical donors increased from 3% to 19%. In 1,032 patients with chronic phase myelofibrosis who received peripheral blood grafts, 38% of those with haploidentical donors were of non-White/ Caucasian ethnicity.

The use of matched sibling donors was independently linked with superior overall survival in the first three months after HCT. Overall survival did not differ; however, with the use of haploidentical, matched unrelated donors, and mismatched unrelated donors in the first three months. With matched sibling donors as a reference, hazard ratios were 5.80 with haploidentical donors, 5.13 with mismatched unrelated donors, and 4.50 with matched unrelated donors, according to the study.

Overall survival differences by donor type in the first three months were related to lower graft failures with matched sibling donors; hazard ratios were 6.11 with haploidentical donors, 2.33 with matched unrelated donors, and 1.82 with mismatched unrelated donors. “This analysis identifies graft failure as a critical unmet need in myelofibrosis HCTs, especially with haplo, and that designing strategies to lower graft failure in haplo-HCT is important to improve outcomes,” the authors wrote.

Beyond 3 months, the study showed that donor type was not associated with relapse, diseasefree survival, or overall survival for patients who underwent HCT within 2 years of myelofibrosis diagnosis.

“The survival gap between matched sibling donors and alternative donor sources has reduced over time. Haplos with post-transplantation cyclophosphamide have made HCT more accessible, especially to patients of non-White ethnicities,” researchers wrote. “Timely consideration of HCT is important, and availability of [a] fully matched donor should not delay HCT.”