Biological and clinical risk factors of chronic lymphocytic leukaemia transformation to Richter syndrome

Predictors of chronic lymphocytic leukaemia (CLL) transformation to Richter syndrome (RS) are not established and were investigated in 185 consecutive CLL cases. Actuarial incidence of RS (n = 17; all diffuse large B-cell lymphomas) at 10 years was 16.2% (95% confidence interval: 8.0-24.4%). At CLL diagnosis, prognosticators of RS by univariate analysis were IGHV homology ≥98% (P = 0.006), IGHV4-39 usage (P < 0.001), del13q14 absence (P = 0.004), expression of CD38 (P < 0.001) and ZAP70 (P = 0.004), size (P < 0.001) and number (P < 0.001) of lymph nodes, advanced Binet stage (P = 0.002), and lactate dehydrogenase (P < 0.001). Multivariate analysis, performed separately for biological and clinical variables, identified CD38 expression [Hazard ratio (HR) = 4.26; P = 0.018], IGHV4-39 usage (HR = 4.29; P = 0.018), and lymph node size ≥3 cm (HR = 9.07; P < 0.001) as independent RS prognosticators. A multivariate model simultaneously analysing biological and clinical variables identified lymph node size ≥3 cm (HR = 6.51; P = 0.001) and del13q14 absence (HR = 4.08; P = 0.031) as independent RS prognosticators. Risk factors of CLL transformation differed from risk factors of CLL progression. These results suggest that CD38 and del13q14 may identify biological subsets of CLL with different RS predisposition. Predominant nodal disease, CD38 expression, IGHV4-39 usage, and absence of del13q14 may help in predicting RS at CLL diagnosis. Close monitoring and a careful biopsy policy are needed in patients carrying transformation risk factors.