Myelodysplastic syndrome (MDS) with isolated trisomy 8: a type of MDS frequently associated with myeloproliferative features? A report by the Groupe Francophone des Myelodysplasies

Isolated trisomy 8 (+8) is a frequent cytogenetic abnormality in the myelodysplastic syndromes (MDS), but its characteristics are poorly reported. We performed a retrospective study of 138 MDS patients with isolated +8, classified or reclassified as MDS (excluding MDS/myeloproliferative neoplasm). Myeloproliferative (MP) features were defined by the repeated presence of one of the following: white blood cell count >10 x 10(9)/l, myelemia (presence of circulating immature granulocytes with a predominance of more mature forms) >2%, palpable splenomegaly. Fifty-four patients (39.1%) had MP features: 28 at diagnosis, 26 were acquired during evolution. MP forms had more EZH2 (33.3% vs. 12.0% in non-MP, P = 0.047), ASXL1 (66.7% vs. 42.3%, P = 0.048) and STAG2 mutations (77.8% vs. 21.7%, P = 0.006). Median event-free survival (EFS) and overall survival (OS) were 25 and 27 months for patients with MP features at diagnosis, versus 28 (P = 0.15) and 39months (P = 0.085) for those without MP features, respectively. Among the 57 patients who received hypomethylating agent (HMA), OS was lower in MP cases (13 months vs. 23 months in non-MP cases, P = 0.02). In conclusion, MP features are frequent in MDS with isolated +8. MP forms had more EZH2, ASXL1 and STAG2 mutations, responded poorly to HMA, and tended to have poorer survival than non-MP forms.