Up-regulation of ribosomal genes is associated with a poor response to azacitidine in myelodysplasia and related neoplasms.

Azacitidine (AZA) is a hypomethylating drug used to treat disorders associated with myelodysplasia and related neoplasms. Approximately 50 % of patients do not respond to AZA and have very poor outcomes. There is thus great interest in identifying predictive biomarkers for AZA responsiveness. We searched for specific genes whose expression level was associated with response status. Using microarrays, we analyzed gene expression patterns in bone marrow CD34+ cells in serial samples from 32 patients with myelodysplastic syndromes, chronic myelomonocytic leukemia, and acute myeloid leukemia with myelodysplasia-related changes before and during the AZA therapy. At baseline, a comparison of the responders and non-responders showed 52 differentially expressed genes (P < 0.01). Functional annotation of the deregulated genes revealed categories primarily related to ribosomes and pathways associated with proliferation. The expression level of RPL28 correlated with overall survival. We identified altered expression in 167 genes in responders, 26 genes in non-responders with stable disease, and 13 genes in non-responders with disease progression using paired t test of expression levels in patients before and during treatment. Our data indicate that AZA treatment failure is associated with the up-regulation of ribosomal genes/pathways that are likely related to intensive proteosynthesis in proliferative/neoplastic cells of non-responders.

TP53 mutation variant allele frequency is a potential predictor for clinical outcome of patients with lower-risk myelodysplastic syndromes.

TP53 mutations are frequently detected in patients with higher-risk myelodysplastic syndromes (MDS); however, the clinical impact of these mutations on the disease course of patients with lower-risk MDS is unclear. In this study of 154 lower-risk MDS patients, TP53 mutations were identified in 13% of patients, with prevalence in patients with del(5q) (23.6%) compared to non-del(5q) (3.8%). Two-thirds of the mutations were detected at the time of diagnosis, and one-third were detected during the course of the disease. Multivariate analysis demonstrated that a TP53 mutation was the strongest independent prognostic factor for overall survival (OS) (HR: 4.39) and progression-free survival (PFS) (HR: 3.74). Evaluation of OS determined a TP53 variant allele frequency (VAF) threshold of 6% as an optimal cut-off for patient stratification. The median OS was 43.5 months in patients with mutations detected at the time of diagnosis and a mutational burden of > 6% VAF compared to 138 months (HR 12.2; p = 0.003) in patients without mutations; similarly, the median PFS was 20.2 months versus 116.6 months (HR 79.5; p < 0.0001). In contrast, patients with a mutational burden of < 6% VAF were stable for long periods without progression and had no significant impact on PFS or OS. Additionally, we found a high correlation in the mutational data from cells of the peripheral blood and those of the bone marrow, indicating that peripheral blood is a reliable source for mutation monitoring. Our results indicate that the clinical impact of TP53 mutations in lower-risk MDS patients depends on the level of mutational burden.