Idelalisib

Idelalisib specifically inhibits P110δ, the delta isoform of the enzyme phosphatidylinositol-4,5-bisphosphate 3-kinase, also known as PI-3K. The PI-3Ks are a family of enzymes involved in cellular functions such as cell growth, proliferation, differentiation, motility, survival and intracellular trafficking, which in turn are involved in cancer. In contrast to the other class IA PI3Ks p110α and p110β, p110δ is principally expressed in leukocytes (white blood cells) and is important for the function of T cells, B cell, mast cells and neutrophils. By inhibiting this enzyme, idelalisib induces apoptosis of malignant cells and inhibits several cell signaling pathways, including B-cell receptor (BCR) signaling and C-X-C chemokine receptors type 5 and type 4 signalling, which are involved in trafficking and homing of B-cells to the lymph nodes and bone marrow. Treatment of lymphoma cells with idelalisib has been shown to result in inhibition of chemotaxis and adhesion, and reduced cell viability.