Select High-Risk Genetic Features Predict Earlier Progression Following Chemoimmunotherapy With Fludarabine and Rituximab in Chronic Lymphocytic Leukemia: Justification for Risk-Adapted Therapy

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Abstract
Purpose: Several new prognostic factors predicting rapid disease progression in chronic lymphocytic leukemia (CLL) have been identified, including unmutated Ig VH mutational status, del(11)(q23), del(17)(p13.1), and p53 mutations. To date, the impact of these same prognostic factors have not been examined relative to treatment outcome with chemoimmunotherapy. Methods: We examined the impact of these new prognostic factors on predicting treatment outcome in symptomatic, untreated CLL patients who received chemoimmunotherapy with fludarabine and rituximab as part of a completed, randomized phase II study, Cancer and Leukemia Group B (CALGB) 9712. Results: Eighty-eight patients treated as part of CALGB 9712 had detailed prognostic factor assessment performed. Using Ig VH mutational status to classify risk, there was no association between complete response rate with either unmutated Ig VH mutational status or high-risk interphase cytogenetics. However, the median progression-free survival (PFS; P = .048) and overall survival (OS; P = .01) were shorter among the Ig VH unmutated patients as compared with the Ig VH mutated patients. Using the hierarchical classification of Döhner, PFS (P = .005) and OS (P = .004) were significantly longer as the classification moved from high risk [del (11)(q22.3) or del (17)(p13.1)] to low risk. Conclusion: These data demonstrate that high-risk CLL patients characterized by Ig VH unmutated (≥ 98%) or high-risk interphase cytogenetics, including either del(17p) or del(11q), appear to have a shorter PFS and OS with chemoimmunotherapy. Larger prospective studies will be required to determine the independent influence of Ig VH mutational status and interphase cytogenetics on treatment outcome.