Patients with chronic lymphocytic leukemia with mutated VH genes presenting with Binet stage B or C form a subgroup with a poor outcome

Dept. of Genetics and Pathology, Uppsala University, Uppsala, Sweden.

BACKGROUND AND OBJECTIVES: The immunoglobulin VH gene mutation status is a strong prognostic indicator in B-cell chronic lymphocytic leukemia (CLL), since unmutated VH genes are correlated with short survival. However, the traditional cut-off level dividing mutated and unmutated cases, i.e. more or less than 2% mutations, has been questioned and other cut-offs have been suggested. We investigated whether an alternative cut-off should be applied and the relation of mutational status to another prognostic marker, Binet staging. DESIGN AND METHODS: VH gene mutation status was assessed in 332 CLL cases by polymerase chain reaction amplification and nucleotide sequencing and was further correlated with overall survival using different VH mutation cut-offs (1-7%) and Binet stage. RESULTS: After testing different mutation borders, the 2% cut-off remained the best discriminative level for determining prognosis. Interestingly, prognostic stratification was improved by combining the information on VH gene mutation status with that of Binet stage: unmutated cases (all stages, n=151, mutated cases with stage A (n=77), and mutated cases with stage B or C (n=37) had a median survival of 82, 179 and 74 months, respectively. INTERPRETATION AND CONCLUSIONS: CLL cases displaying mutated VH genes with Binet stage B or C had a survival similar to that of unmutated cases and significantly shorter than that of mutated stage A CLL. Our result reveals clinical heterogeneity within the VH mutated CLL group by inclusion of Binet stage data, a finding which is of importance when considering surrogate marker(s) for VH mutation status.

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