BCR and B-cell chronic lymphocytic leukemia: Idelalisib is a first-in-class inhibitor of phosphatidylinositol-3-kinase delta (PIK3-delta), another component of the BCR signaling pathway, and is indicated in combination with an anti-CD20 monoclonal antibody (rituximab or ofatumumab) for the treatment of CLL in adult patients and as monotherapy for the treatment of follicular lymphoma in adult patients (https://www.ema.europa.eu/documents/product-information/zydelig-epar-product-information_en.pdf).