Venetoclax Resistance Landscape in Chronic Lymphocytic Leukemia

Who May Qualify: - Age greater than or equal to 18 years old; - chronic lymphocytic leukemia diagnosis according to iwCLL criteria; - refractory and/or relapsed disease during or after venetoclax treatment; - tumor samples available. - Relapse might be progressive chronic lymphocytic leukemia or transformation into Richter syndrome. - Patients must be able to express their opposition to be enrolled in this study, if need be. - Patients must be affiliated at the French Social Security system Who Should NOT Join This Trial: Patients of their legal guardians refusing to participate \- Always talk to your doctor about whether this trial is right for you.