Near-Tetraploidy Is Strongly Associated with Development of Richter's Transformation in Chronic Lymphocytic Leukemia Patients Receiving Ibrutinib

Ibrutinib is a promising targeted therapy for chronic lymphocytic leukemia (CLL). However, a small subset of patients progress on ibrutinib either through progressive CLL or Richter's transformation. Patients responding to ibrutinib and then progressing with Richter's transformation do so most commonly within the first 2 years of treatment and have an extremely poor prognosis. Identifying biomarkers associated with this transformation is of utmost importance. Near-tetraploidy (4 copies of most chromosomes within a cell) has been reported in various lymphomas; however, its incidence in CLL has not been described. We investigated the prevalence of near-tetraploidy in CLL patients prior to starting ibrutinib and identified it as a pre-treatment biomarker for Richter's transformation.