HLA Class I Genotypes Predict the Survival after Hematopoietic Stem Cell Transplantation in Immune Aplastic Anemia

Introduction Immune aplastic anemia (AA) is a bone marrow failure syndrome mediated by cytotoxic T cells, leading to the loss of HLA class I allele expression in hematopoietic stem and progenitor cells. In unrelated hematopoietic stem cell transplantation (HSCT), we recently reported an association...

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Published in:Blood 2023-11, Vol.142 (Supplement 1), p.706-706
Main Authors: Zaimoku, Yoshitaka, Yamazaki, Hirohito, Kanaya, Minoru, Hiramoto, Nobuhiro, Ishiyama, Ken, Uchida, Naoyuki, Doki, Noriko, Yamamoto, Ryusuke, Nishida, Tetsuya, Onodera, Koichi, Machida, Shinichiro, Kanda, Yoshinobu, Eto, Tetsuya, Ishimaru, Fumihiko, Onizuka, Makoto, Ichinohe, Tatsuo, Atsuta, Yoshiko, Onishi, Yasushi
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Language:English
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Summary:Introduction Immune aplastic anemia (AA) is a bone marrow failure syndrome mediated by cytotoxic T cells, leading to the loss of HLA class I allele expression in hematopoietic stem and progenitor cells. In unrelated hematopoietic stem cell transplantation (HSCT), we recently reported an association between HLA loss and a short time to transplantation (TTT), consistent with an abrupt onset of immune AA. In addition, patients who lost HLA-A*02:06 or HLA-B*40:02 showed better survival outcomes after HSCT than those with other HLA allele losses. To clarify the clinical significance of the loss of specific HLA class I alleles in AA, we correlated loss-prone HLA class I allele genotypes with HSCT outcomes in patients with a short TTT, assuming the frequent absence of these alleles in this subgroup. Methods We conducted a nationwide retrospective analysis of patients with acquired AA ≥16 years old who underwent their first allogeneic HSCT in Japan between 2006 and 2020. Patient data were obtained from the Transplant Registry Unified Management Program (TRUMP ®), a comprehensive Japanese HSCT registry. Results From 1025 patients with acquired AA, we excluded patients with drug-induced AA and those missing 2-field HLA allele information and TTT information, leaving 874 patients for the analysis. The median patient age at HSCT was 34 years old, and the median TTT was 14 months. When focusing on the most frequently absent HLA class I alleles in Japanese patients with AA, including HLA-B*40:02, HLA-A*02:06, HLA-A*02:01, HLA-B*54:01, and HLA-A*31:01, all 5 alleles were associated with higher survival rates than in 220 patients without these alleles (Figure 1A). As expected, this association was more pronounced with a shorter TTT. For instance, among the 424 patients with a TTT
ISSN:0006-4971
1528-0020
DOI:10.1182/blood-2023-191332