Myelodysplastic Syndromes with Isolated 20q Deletion: A New Clinical-Biological Entity?
Authors: De Benedittis Daniela , Fianchi Luana , Niscola Pasquale , Piccioni Annalina , Di Veroli Ambra , Campagna Alessia , Mancini Stefano , Villivà Nicoletta , Mohamed Sara , Carmosino Ida , Criscuolo Marianna , Fenu Susanna , Aloe Spiriti Maria Antonietta , Buccisano Francesco , Breccia Massimo , Mancini Marco , Latagliata Roberto 
Published: October 2019

Abstract
Deletion of the chromosome 20 long arm (del20q) has been reported in 3-7% of patients with Myelodysplastic Syndromes (MDS). In particular, isolated del20q seems to be associated with good prognosis, low risk of progression to AML and prolonged survival: however, very few reports addressed this subset of MDS patients up to now.
To highlight this issue, we collected data from all patients with MDS and isolated del20q diagnosed and followed by Centers of the Gruppo Romano-Laziale Sindromi Mielodisplastiche (GROM-L).
On the whole, 53 patients were analysed: the main features at diagnosis of these patients are reported in the Table. Platelet (PLT) count was < 100 x 109/l in 28 patients (52.8%), Hb level was < 10.0 g/dl in 23 patients (43.3%) and neutrophil count was < 1.0 x 109/l in 12 patients (22.6%).
As to risk prognostication, according to IPSS score 51 patients (96.2%) had low/intermediate-1 risk and 2 (3.8%) had intermediate-2/high risk: according to r-IPSS, 8 patients (15.1%) had very low risk, 20 (37.7%) low risk, 19 (35.9%) intermediate risk and 6 (11.3%) high risk.
During follow-up, 14 patients (26.4%) did not need any therapy and were only observed, 36 (67.9%) were treated with Erythropoietin (EPO), 1 (1.9%) with hypomethylating agents, 2 (3.8%) with other treatments (TNF-α inhibitor, interferon). Among the 36 patients treated with ESA after a median interval from diagnosis of 5.0 months [interquartile range (IR) 1.2 - 27.6], 24 (66.6%) received α-EPO, 11 (30.5%) β-EPO and 1 (2.9%) darbopoietin. Two patients were too early (< 3 months of treatment) for response evaluation: among the 34 evaluable patients, 21 (61.7%) achieved stable erythroid response according IWG criteria (Hb increase > 1.5 g/dl in 18 patients and reduction > 50% of basal transfusion requirement in 3 patients) while 13 (38.2%) were resistant to EPO.
Nine patients (17%) progressed to Acute Myeloid Leukemia (AML) after a median time from diagnosis of 16.8 months (IR 4.1 - 51.7). At the last follow-up, 21 patients (39.6%) died (13 from MDS/AML related causes and 8 from unrelated causes), 12 (22.6%) were lost to follow-up and 20(37.8%) were alive. Median Overall Survival (OS) of the entire cohort was 61.6 months (95%CI 42.2 - 81.0): the 10-year cumulative OS was 38.6% (95%CI 18.6 - 58.6) (Figure 1).
In conclusion, as MDS represent a heterogeneous group of pathologies, many efforts are ongoing to identify patients with similar biological, clinical and prognostic features (eg 5q- syndrome, MDS with ring sideroblasts). From the scarce data in the literature and from our results, it is reasonable that also patients with isolated del20q may represent a distinct clinical and biological entity, with specific clinical and prognostic features (low PLT count, low number of marrow blasts, low IPSS and r-IPSS risk score, good response to EPO, long OS). The mechanisms underlying del20q are still unclear and warrant future molecular analysis.

Disclosures
Breccia: Novartis: Honoraria; BMS: Honoraria; Pfizer: Honoraria; Incyte: Honoraria.