TP53 and B-cell chronic lymphocytic leukemia: TP53 mutations and/or del(17p) are especially common in relapsed CLL and are associated with reduced overall survival.23, 24, 25 Other somatic gene mutations, including ATM, NOTCH1, SF3B1, and BIRC3, have been identified as prognostic markers, but only TP53 is consistently associated with therapy resistance and early relapse.