Excellent Prognosis of Low-Risk Myelodysplastic Syndromes (MDS) Without Detectable Myeloid-Related Mutations

Background: Unexplained cytopenia (UC) and low-risk myelodysplastic syndrome (MDS) are distinguished mainly by morphologic dysplasia, which sometimes shows inter-observer discrepancy. We hypothesized that gene mutations are strong prognostic factors for these low-risk patients. Materials and methods: We enrolled patients from 4 medical centers with unexplained cytopenia of at least 1 lineage. Diagnosis of low-risk MDS was made according to WHO 2016 classification and a revised international prognostic scoring system (R-IPSS) score of = 3.5. DNA was extracted from bone marrow or blood and sequenced by targeted next generation sequencing (NGS). Results: One hundred twenty-one patients were recruited: 25% with UC and 75% with low-risk MDS. Complete blood counts were similar, but low-r isk MDS patients carried higher numbers of mutations (1 vs. 0; P =.04) than UC patients. Overall, the most frequent mutated genes were TET2 (14.6%), SF3B1 (12.2%), and ASXL1 (9.7%). Survival rates of low-risk MDS patients versus UC patients were not significantly different. UC patients and low-risk MDS patients without genetic abnormalities showed superior 5-year progression free survival compared to MDS patients with mutations (100% vs. 76.0%; P =.005). Overall, ASXL1 mutations were associated with decreased 4-year overall survival compared to wild-type (59% vs. 31%; P =.01). In a multivariate analysis, ASXL1 and DNMT3A mutations in low-risk MDS patients were associated with a higher risk of disease progression with hazard ratios of 7.88 (95% CI 1.76-35.32, P =.01) and 7.45 (95% CI 1.61-34.46, P =.01), respectively. Conclusion: Mutation detection is important for proper risk stratification of patients presenting with idiopathic cytopenia.