The Predominant Prognostic Significance of NOTCH1 Mutation Defined by Emulsion PCR in Chronic Lymphocytic Leukemia

PURPOSE: NOTCH1(mut) represents a new prognostic marker in chronic lymphocytic leukaemia (CLL). The low sensitivity of the current methods may increase the risk of false-negative results, particularly in patients with low NOTCH1(mut) allelic burden. This study compared two methods of the NOTCH1(mut) assessment including droplet digital PCR (ddPCR) and amplification-refractory mutation system PCR (ARMS-PCR) untreated CLL patients. PATIENTS AND METHODS: This study included 319 untreated CLL patients. Two PCR-based methods; ddPCR and ARMS-PCR were performed to assess the mutational status of NOTCH1. The Mann–Whitney, Fisher’s exact test, Kruskal–Wallis, Kaplan–Meier, Log rank tests and multivariate Cox proportional hazard regression model were used to analyze collected data. RESULTS: We proved that ddPCR increased the detectability of the NOTCH1(mut) compared to ARMS-PCR in CLL (18.55% vs 6%). We showed a shorter time to first treatment (TTFT) in the NOTCH1(mut) group of patients compared to the NOTCH1(wt) defined by ddPCR (1.5 vs 33 months, p=0.01). The TTFT survival curves analysis in subgroups divided according to the mutational status of IGHV and NOTCH1 assessed by ddPCR discriminated group with the best prognosis: IGHV(mut)NOTCH1(wt). Multivariate analysis revealed that the mutational status of IGHV represented an independent prognostic factor for TTFT, while NOTCH1(mut) determined by ddPCR constituted as a dependent prognostic factor for TTFT. CONCLUSION: The selection of the precise method of NOTCH1(mut) detection as ddPCR might significantly improve prognostic stratification of CLL patient. Assessment of IGHV might be relevant to more accurate discrimination of prognostic groups of CLL patients, especially in harboring NOTCH1(mut) irrespective of the quantity of allelic burden.