Interpreting CLL17 and Depth of Response in Frontline CLL

Sameh Gaballa, MD, of Moffitt Cancer Center, asks the faculty to interpret CLL17, the first phase 3 trial to compare fixed-duration and continuous therapy in treatment-naive chronic lymphocytic leukemia (CLL). Andrew H. Lipsky, MD, of Columbia University Irving Medical Center, likens the 3-year readout to checking a marathon at mile 3: all 3 strategies are well tolerated and progression-free survival (PFS) is similar, but separation in CLL emerges later, since the TP53 signal with Bruton tyrosine kinase (BTK) inhibitors takes 5 to 6 years to appear. M. Yair Levy, MD, of Texas Oncology–Baylor Charles A. Sammons Cancer Center, notes that subgroups with 17p deletion or TP53 mutation already show shorter PFS than continuous BTK inhibition and expects that gap to widen. On depth of response, Dr Lipsky considers measurable residual disease irrelevant for continuous therapy and only partly predictive for time-limited therapy, since many patients become MRD positive again.