From Mild Cytopenia to Overt MDS and AML, the Mutational Profile Predicts Progression, but Not Survival
Authors: Hansen Jakob Werner , Johansen Morten Munk , Westman Maj Karoline , Saft Leonie , Sjö Lene Dissing , Marcher Claus Werenberg , Holm Mette Skov , Dimitriou Marios , Karimi Mohsen , Raaschou-Jensen Klas , Glenthøj Andreas Birkedal , Severinsen Marianne Tang , Hellström-Lindberg Eva , Andersen Mette Klarskov , Grønbæk Kirsten 
Published: October 2019

Abstract
Purpose: Recurrently mutated genes have been identified in patients with myelodysplastic syndromes (MDS) and, more recently, in patients with unexplained cytopenia. (Kwok et al. Blood 2015, Hansen et al. American Journal of Hematology 2016 and Malcovati et al. Blood 2017). In this study, we investigated the prognostic impact of these mutated genes in patients with idiopathic cytopenia and compared them to a control cohort of patients with low risk MDS.
Methods: We included patients with idiopathic cytopenia after routine assessment, without cytogenetic abnormalities. For comparison, a group of low risk MDS patients without cytogenetic abnormalities, excess of blasts or ring sideroblasts were included. All samples were sequenced covering at least the 20 most recurrently mutated genes in MDS, and a subset of cases underwent a blinded morphology review by two hematopathologists.
Results: Two hundred and forty nine patients, 171 with idiopathic cytopenia and 78 with low risk MDS, were included in this study. Of these, 80 (47%) and 53 (68%), respectively, had one or more detectable mutations. There was no difference in survival between the groups, however a predefined subset of "adverse mutations" (ASXL1, NRAS, SRSF2, U2AF1, TP53, RUNX1, EZH2, IDH2 and GATA2, adopted from Bejar et al. Current Opinion in Hematology 2017) was associated with inferior survival in the MDS group (p= 0.035), but not in the group with idiopathic cytopenia and at least one mutation (p= 0.43) (Figure 1). However, if an adverse mutation was present in the idiopathic cytopenia group the risk of progression to MDS or AML increased significantly (HR [CI:95%] 12.01 [1.47; 98.23], p= 0.02), after adjusting for age and sex. Thus mutational screening identified the patients with unexplained cytopenia at risk of progressing to an overt myeloid neoplasm (Figure 2). A total of 18 patients (23%) progressed to a myeloid neoplasm during follow up, of those 12 had material available at time of progression. All patients who progressed to AML (n=4) acquired a new driver mutation at time of progression, in contrast to the patients who progressed to MDS or CMML (n=8) without excess of blasts, who showed a clonal expansion or a steady variant allele frequency at the time of progression.
TET2 and DNMT3A mutations were more frequent in patients with idiopathic cytopenia, and were associated with less dysplasia of bone marrow cells. A total of 109 cases with idiopathic cytopenia underwent a blinded morphology review by two independent reviewers; ten cases were concordantly reclassified to fulfill the criteria for MDS, and all of these had at least two mutations. None of these have progressed to higher risk MDS and these ten are not included in the 18 patients mentioned above, who progressed to MDS, CMML or AML during follow up.
Conclusion: We here show that mutational profiling can identify patients with idiopathic cytopenia who are at risk of progression, but in contrast to low-risk MDS, the presence of adverse mutations in patients with idiopathic cytopenia do not predict inferior survival.

Disclosures
Hansen: Otsuka Pharma: Membership on an entity's Board of Directors or advisory committees. Grønbæk:Janssen Pharma: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Otsuka Pharma: Membership on an entity's Board of Directors or advisory committees.