Correlation between Real-World Progression-Free Survival (rwPFS) and Overall Survival (OS) in Patients with Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma (CLL/SLL) Who Relapsed or Are Refractory, Intolerant, Resistant to Treatment with a Bruton's Tyrosine Kinase Inhibitor (BTKi)

Introduction:Given the long maturation time of OS, PFS is often used in oncology and hematology as a surrogate for OS. However, the association between the two endpoints varies across cancer types. In CLL clinical trial populations, PFS and OS were shown to be strongly correlated in patients receiving at least two lines of therapy (LOT). The present study used real-world individual patient data to evaluate the strength of correlation between real-world PFS (rwPFS) and OS in CLL/SLL patients who relapsed or were resistant/refractory/intolerant to treatment with a covalent BTKi.