Microrna-29c and microrna-223 downregulation has in vivo significance in chronic lymphocytic leukemia and improves disease risk stratification 

Stamatopoulos B, Meuleman N, Haibe-Kains B, Saussoy P, Van Den Neste E, Michaux L, Heimann P, Martiat P, Bron D, Lagneaux L

Background: Aberrant expression of microRNAs has been recently associated with chronic lymphocytic leukemia (CLL) outcome. Although disease evolution can be predicted by several prognostic factors, a better outcome individualization in a given patient is still of utmost interest.

Methods: In the current study, we investigated the expression of two microRNAs, miR-29c and miR-223, by real-time PCR (qPCR), compared them to other biological or clinical markers and assessed a qPCR score to better predict CLL outcome.

Results: We showed that miR-29c and miR-223 expression levels decreased significantly with progression from Binet stage A to C (n=110), were significantly lower in poor prognostic subgroups defined by cytogenetic abnormalities (n=81), IgVH mutational status (n=104), lymphocyte doubling time (n=93), solubleCD23 (n=91), beta-2-microglobulin (n=78), zeta-associated protein 70 (ZAP70) (n=110), lipoprotein lipase (LPL) (n=110) and CD38 expression (n=104) and could significantly predict treatment-free survival (TFS) and overall survival (OS) (n=110). We subsequently developed a qPCR-score combining miR-29c, miR-223, ZAP70 and LPL (from 0 to 4 poor prognostic markers) to stratify treatment and death risk in a cohort of 110 patients with a median follow-up of 72 months (range, 2-312). Patients with a score of 0/4, 1/4, 2/4, 3/4, and 4/4 had a median TFS of >312, 129, 80, 36 and 19 months, respectively (hazard ratio, HR=17.00, P< 0.0001). Patients with a score of 0-1/4, 2-3/4 and 4/4 had a median OS of >312, 183 and 106 months, respectively (HR=13.69, P=0.0001). Finally, in Binet stage A patients (n=77), this score remained relevant and significant for TFS and OS prediction (HR=18.56, P< 0.0001 and HR=12.5, P=0.0068, respectively).

Conclusions: miR-29c and miR-223 levels were decreased in poor prognostic patient subgroups. A low level of these microRNAs was associated with disease aggressiveness, high tumor burden and poor outcome; we proposed and validated a qPCR score to better predict the evolution of individual CLL patients. This score will help to identify patients who will need early therapy and thus require a closer follow-up.