Clonal Dynamics of Chronic Lymphocytic Leukaemia Treated With Pirtobrutinib After Previous Treatment With Zanubrutinib

This study is tracking how the cancer cells in patients with chronic lymphocytic leukemia (CLL) — a slow-growing blood cancer — change and evolve when treated with a drug called pirtobrutinib, after they have already been treated with another drug called zanubrutinib. By studying these 'clonal dynamics,' researchers hope to understand why some patients respond better than others and how resistance develops. **You may be eligible if...** - You have a confirmed diagnosis of CLL - Your most recent prior treatment was zanubrutinib, and you received at least one 28-day cycle of it - Your doctor has determined you need to start a new line of treatment - You are willing to provide blood and tissue samples for research **You may NOT be eligible if...** - You have not previously been treated with zanubrutinib - You are not yet in need of further treatment - You do not meet the health criteria required to safely start pirtobrutinib Talk to your doctor to see if this trial is right for you.