“…lymph node and peripheral blood) and showed that mutations in the lymph nodes expand in the peripheral blood at relapse following positive selection by therapy (Schuh et al , ; Del Giudice et al , ; Rose‐Zerilli et al , ). Using NGS and copy number alteration/aberration analysis of leukaemic cells isolated simultaneously from peripheral blood and lymph node of nine CLL patients, Del Giudice et al () identified specific subclonal mutations in each compartment and cases with clonal driver aberrations within lymph nodes ( SF3B1 mutation, BIRC3 deletion, del8p and gain 2p) that were only detected in the blood as small circulating subclones. Several groups have reported on acquired ibrutinib resistance and BTK and PLCG2 mutations in patients with CLL who progressed on ibrutinib therapy (Woyach et al , ; Burger et al , ; Ahn et al , ).…”