From the Journals

Allele-matching in cord blood transplant yields better survival

 

Key clinical point: HLA matching at the allele-level produces better survival in umbilical cord blood transplantation for nonmalignant diseases.

Major finding: Mortality risks were significantly higher for patients who received transplants with two (P = .018), three (P = .0001), and four or more mismatches (P less than .0001), compared with those whose transplants were fully matched at all eight alleles at HLA-A, HLA-B, HLA-C and HLA-DRB1.

Data source: A retrospective review of 1,199 cases reported to the Center for International Blood and Marrow Transplant Research (CIBMTR) or the European Group for Blood and Marrow Transplant (EGBMT).

Disclosures: The authors reported no conflicts of interest.


 

FROM THE LANCET HAEMATOLOGY

Matching down to the allele level in umbilical cord blood transplantation between unrelated donors results in greater overall survival for those with nonmalignant diseases, such as aplastic anemia, researchers found in a retrospective study published in the Lancet Haematology.

The review (Lancet Haematol. 2017 Jul;4[7]:e325-33), the largest published on the topic, indicates that clinicians should change practice from the current standard of antigen-level matching, said Mary Eapen, MD, director of the Center for International Blood and Marrow Transplant Research (CIBMTR) in Wauwatosa, Wisconsin.

“Our findings,” Dr. Eapen wrote, “support a change in clinical practice to prioritization of units on allele-level HLA matching at HLA-A, HLA-B, HLA-C, and HLA-DRB1.”

Data were pulled from cases reported to the Center for International Blood and Marrow Transplant Research or the European Group for Blood and Marrow Transplant. Researchers looked at 1,199 donor-recipient matches of cord blood transplantation for diseases, such as severe combined immunodeficiency (SCID), non-SCID primary immunodeficiency, inborn errors of metabolism, severe aplastic anemia, and Fanconi anemia. Recipients could be as old as age 16, but most were age 5 or younger.

After adjustment for factors, including cytomegalovirus serostatus, the intensity of the conditioning regimen, and the total nucleated cell dose, the 5-year overall survival was 79% for transplants that were matched at all eight alleles at HLA-A, HLA-B, HLA-C and HLA-DRB1. These results compare with 76% after transplants with one mismatch, 70% with two mismatches, 62% with three mismatches, and 49% with 4 or more mismatches.

Mortality risks were significantly higher for patients who received transplants with two (P = .018), three (P = .0001), and four or more mismatches (P less than .0001), compared with those whose transplants were fully matched. There was no difference statistically between full matches and one mismatch, but the findings suggest that the mortality risk might prove significant with a larger sample size.

Researchers cautioned that, because most patients were age 5 or younger, the results might not be generalizable to older children.

Although HLA typing is available at CIBMTR for most blood cord transplants for nonmalignant diseases, full allele matches or just one mismatch are not the norm, Dr. Eapen wrote. Researchers said that they suspect this is because of difficulties finding matches or because a high total nucleated cell count is prioritized above HLA matching. They suggest clinicians change their decision making in this regard.

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