In a Phase III trial comparing duvelisib to ofatumumab in R/R CLL, the dual PI3K inhibitor showed superior ORR (74% vs. 45%) and PFS (13 months vs. 10 months), but a high rate of severe adverse effects (Grade ≥ III in 87% of patients: neutropenia 30%, diarrhea 15%, pneumonia 14% and anaemia 13%). The gene discussed is PIK3CD; the disease is B-cell chronic lymphocytic leukemia.