This study represents a groundbreaking exploration of the genomic landscape of MNs within a Korean cohort, analyzing an extensive dataset from 1,585 patients. Moving beyond the scope of previous research, which targeted specific MN categories (2, 4, 5, 7, 9), our study encompassed a broad spectrum of the disease, unveiling a comprehensive understanding of its genomic diversity. This approach not only broadens the existing knowledge base but also sets a new benchmark for future genomic analyses of MNs.
We elucidated the genomic association in MNs and identified 11 genomic subgroups, ranging from DP1 to DP10, each exhibiting unique genomic characteristics, alongside a distinct DP0 lacking these characteristics. Certain subgroups, notably DP1 and DP5, are distinguished by their unique mutational profiles ─ JAK2 in DP1 and CALR in DP5 ─ and associated clinical and laboratory features of MPNs, leading to a very favorable prognosis.
Conversely, other subgroups, such as DP2, are not confined to a specific disease entity, encompassing a range of conditions, including MDS irrespective of blast percentage, MPN, and MDS/MPN, and even AA. These are characterized by the presence of TP53 mutations and/or complex karyotypes, associated with a very adverse prognosis. We further clarified the biological and prognostic importance of NPM1 mutations, now classified as a distinct AML entity, applicable regardless of blast percentage in both MDS and AML (3, 8). Although limited to 21 cases, individuals classified within DP9 stood out from other subgroups due to their very adverse outcomes, indicating the need for a distinct therapeutic strategy for MDS with NPM1 (14, 15). Additionally, the discovery of subgroup DP9, spanning a variety of MNs beyond MDS to include MDS/MPN, validates the recent 5th WHO classification and underscores the need for its expanded use in disease classification. Subgroup DP7, distinguished by SETBP1 mutations, has been associated with leukemic evolution in progenitors harboring ASXL1, NRAS, and CSF3R mutations via specific pathways (16–18), indicating a very adverse prognosis. This subgroup appears across various MNs, including MDS, CMML, CNL, and JMML. Given its association with high-risk, HSCT is recommended, irrespective of phenotype presentation. Beyond delineating three subgroups based on genomic profiles and their association with a very adverse prognosis, our analysis suggests that patients within these groups may benefit from HSCT.
DP4, characterized by TET2 and/or SRSF2 mutations, included a significant number of patients (n = 93) across MDS, MPN, and MDS/MPN, exhibiting an adverse prognosis. While the prognosis for DP4 was better than that for subgroups DP2, DP9, and DP7, it was poorer compared to other subgroups. We also identified two subgroups: DP3, characterized by mutations in U2AF1, + 8, RUNX1, and BCOR; and DP6, marked by mutations in CBL, ETV6, and KMT2D. The majority were classified within MDS, with a smaller proportion in MPN and even fewer in MDS/MPN, all of which exhibited an intermediate prognosis.
DP10 was characterized by various mutations associated with favorable prognoses, including SF3B1, DDX41, isolated 5q-, MPL or –Y mutations. Our findings provide additional insight that patients with DDX41 mutations share a similar prognostic status with those harboring SF3B1 mutations or isolated 5q-. This suggests a potential need to re-evaluate current risk stratification systems to incorporate DDX41 status (19, 20). In addition, + 1/1q + and der(1;7) represent common chromosomal abnormalities in MNs (21, 22), with der(1;7) being the most prevalent, accounting for 1.5–6% of patients with MDS and AML. While der(1;7) leads to both 7q- and 1q+, a prior study suggested categorizing der(1;7) as a distinct entity due to its comparatively better outcomes than those observed in cases with only − 7/7q- (21). Our study builds upon these findings, offering additional evidence to justify classifying der(1;7) as a subgroup with a favorable prognosis.
The last group, DP0, identified by the absence of specific genomic features, predominantly includes cases of AA and hypoplastic MDS. Distinguishing between hypoplastic MDS and AA presents a challenge due to the scarcely observable cells in the BM. However, our results underscore the distinct biological underpinnings of hypoplastic MDS, affirming its similarity to AA. This insight helps bridge the conceptual gap between malignancies and immune-mediated disorders (6, 23).
This study has several limitations. AML cases were excluded during the study design due to the prevalence of gene fusions and well-defined mutations in many cases. However, including myelodysplasia-related AML may have offered valuable insights into the connection between genomic risk groups and increased blast counts. Furthermore, the validation cohort, derived from the same institution, was relatively small. Consequently, there is a need for multicenter, large-scale studies to further validate and expand upon our findings.
In conclusion, our study aimed to elucidate the intricate genomic landscape underlying cytogenetic and molecular genetic abnormalities across a spectrum of overlapping MNs. We successfully identified subgroups that transcend specific disease diagnoses, instead grouping them by overarching disease categories. These subgroups not only highlight genetic events pivotal in disease development and prognosis but also inform the selection of patients who could benefit from HSCT. Our study addresses the prognostic needs of relatively uncommon disease categories, which are frequently overlooked in existing prognostication systems. Our results provide valuable insights into these lesser-studied MN categories, laying the foundation for the development of personalized therapeutic strategies.