The chronic lymphocytic leukemia international prognostic index (CLL-IPI) predicts time to first treatment in early CLL: Independent Validation in a Prospective Cohort of Early Stage Patients

摘要

The chronic lymphocytic leukemia International Prognostic Index (CLL-IPI) combines 5 parameters (age, clinical stage, TP53 status [normal vs. del(17p) and/or TP53 mutation], IGHV mutational status, serum β2-microglobulin) to predict survival and time-to-first-treatment (TTFT) in CLL patients. We performed an observational study in 337 prospectively collected, Binet stage A patients to validate the ability of the CLL-IPI to predict TTFT in an independent cohort of early stage CLL patients. The CLL-IPI score stratified Binet stage A patients into three subgroups with different outcome. Since the CLL-IPI was originally developed to predict survival, we next investigated the optimal cut-off score to predict TTFT in Binet stage A patients. Recursive partitioning analysis identified three subsets with scores of 0 (n=139), 1 (n=90), and ≥ 2(n=108). The probability of remaining free from therapy 5 years after diagnosis was 85%, 67% and 46% in these three categories (P<0.0001.; C-statistic:c=0.72; 95% CI:0.58–0.81). This optimized CLL-IPI scoring for TTFT was subsequently validated in an independent cohort of Binet A patients from the Mayo Clinic (n=525). The ability of either original or optimized CLL-IPI to predict TTFT was equivalent to other prognostic models specifically designed for this endpoint (2011 MDACC score and O-CLL1 score). Although originally developed to predict suvival, the CLL-IPI is useful for predicting TTFT in early stage CLL patients.