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.
Multivariate analysis selected stereotyped BCR (HR, 3.33; P = 0.001) and IGHV4-39 usage (HR, 4.03; P = 0.004) as independent predictors of RS transformation.
Importantly, although some risk factors predict both CLL progression and transformation to RS, others (CD38 genotype, absence of del13q14, IGHV4-39 usage, stereotyped B-cell receptor) appear to specifically predict RS.
Subset #6 (IGHV1-69/IGKV3-20) is less aggressive compared to subset #8 (IGHV4-39/IGKV1(D)-39) which has the highest risk for Richter's transformation among all CLL.