Genomic Aberrations Dramatically Improve The Strong Prognostic Impact Of IGHV Mutational Status In Chronic Lymphocytic Leukemia (CLL)

CLL is a heterogeneous disease with patients (pts) experiencing rapid disease progression and others living for years without requiring treatment. Recently, next generation sequencing has revealed new molecular alterations, targeting the NOTCH1 and BIRC3 genes which occur in about 10% CLL at diagnosis and correlate with poor outcome. Given the possibility of targeting NOTCH1 and BIRC3 with drugs currently under development, the primary endpoints of our research were: 1) to determine overall survival (OS) upon IGHV, NOTCH1, TP53 and BIRC3 in univariate analysis; 2) to correlate these genomic aberrations with other biological or clinical prognostic factors, and finally 3) to confirm NOTCH1, BIRC3 and TP53 as independent prognostic factors. We investigated 475 pts with a median age of 65 years (range 33-89), whose 160 had low Rai stage, 301 intermediate stage and 14 high stage. NOTCH1 mutations (mut) were studied by ARMS PCR for c.7544-7545delCT and by Sanger sequencing of NOTCH1 exon 34. Mutations of TP53 were analysed by DNA direct sequencing, while BIRC3 disruption (disr) was studied by Sanger sequencing for mutations and by interphase FISH for deletions. All these alterations were studied at diagnosis or before any chemotherapeutic approach. NOTCH1^mut and TP53^mut pts were 52 (10.9%) and 36/475 (7.6%), respectively. Thirty four patients were BIRC3^mut (7.2%) and 26 BIRC3 deleted (5.5%) for a total of 46 cases (9.7%) BIRC3^disr. NOTCH1, TP53 and BIRC3 alterations were mutually exclusive. There were significant correlations between NOTCH1 (P<0.00001), TP53 (P=0.004), BIRC3 status (P=0.00004) and IGHV mutations. Concerning FISH cytogenetics (460 patients), a significant correlation (P<0.0001) was found between NOTCH1^mut and trisomy 12 (20/62; 32%). TP53^mut were strictly associated with del17p (15/25; 60%; P<0.0001), while BIRC3^disr was found mainly within 11q22-q23 deletions subset (22/46;49%; P<0.0001). With regard to clinical outcome, 30 (83%) of 36 TP53^mut pts (P=0.00009), 47 (90%) of 52 NOTCH1^mut (P<0.00001) and 40 (87%) of 46 BIRC3^disr pts had received chemotherapy at the time of analysis. Twenty nine NOTCH1^mut (56%), 15 TP53^mut (42%) and 18 BIRC3^disr (39%) pts underwent at least two lines of treatment (P<0.0001). Noteworthy, shorter OS was observed in IGHV unmutated (UM) patients (12% vs 80% at 18 years, P<0.00001), in NOTCH1^mut pts (12% vs 71% at 16 years, P<0.00001), in TP53^mut pts (9% vs 76% at 14 years, P<0.00001) and in BIRC3^disr pts (29% vs 65% at 16 years, P=0.00001). To further explore the prognostic impact of NOTCH1^mut, TP53^mut and BIRC3^disr, we investigated them within the UM (153 pts) IGHV subset, notoriously at worst prognosis. As a matter of fact, NOTCH1^mut (16% vs 45% at 14 years, P=0.012), TP53^mut (0% vs 43% at 13 years, P=0.002) and BIRC3^disr (0% vs 57% at 11 years, P=0.011) pts showed significant shorter OS [Figure]. Within the mutated IGHV subgroup we obtained similar results. In multivariate analysis of OS, TP53^mut (HR 5.2, P<0.00001), age >60 years (HR 3.8, P=0.00002), IGHV UM status (HR 0.30, P=0.0001), intermediate/high Rai stages (HR 2.8, P=0.0002), NOTCH1^mut (HR 2.6, P=0.001), and BIRC3^disr (HR 2.5, P=0.005) were confirmed to be independent adverse prognostic factors. Noteworthy, here, we demonstrated that genomic aberrations are able to improve the historical prognostic ability of the IgHV mutational status. In conclusion, genomic aberrations, particularly TP53^mut, NOTCH1^mut and BIRC3^disr should be considered as novel important prognostic parameters in CLL and therefore they have to be necessarily considered in updated scoring prognostic systems.