Phosphoinositide 3-kinase delta and Phosphoinositide 3-kinase gamma (PI3Kδ/γ)

Phosphoinositide 3-kinase delta (PI3Kδ) and gamma (PI3Kγ) are lipid kinases belonging to the Class I PI3K family, specifically enriched in hematopoietic cells such as B cells, T cells, and myeloid cells (UniProt O00329, P48736). PI3Kδ is a key mediator of B-cell receptor signaling and is essential for B-cell development and function, while PI3Kγ is primarily activated by G-protein-coupled receptors and plays a vital role in myeloid cell recruitment and T-cell activation (PubMed: 29042364). In the context of oncology, these isoforms are often overexpressed or hyperactivated, driving the survival and proliferation of malignant cells in diseases like chronic lymphocytic leukemia (CLL) and various lymphomas (NIH: StatPearls). Furthermore, PI3Kγ contributes to an immunosuppressive tumor microenvironment by promoting the polarization of pro-tumorigenic macrophages. Dual inhibition of PI3Kδ and PI3Kγ, exemplified by the drug duvelisib, provides a dual-action approach by directly inducing apoptosis in cancer cells and disrupting the supportive inflammatory signals from the microenvironment (FDA: Copiktra Label). Despite their efficacy, therapeutic targeting of these isoforms is associated with significant immune-related adverse events, including colitis, hepatotoxicity, and pneumonitis, due to their broad roles in immune homeostasis.

Other names

PI3K delta/gammap110δ/p110γPIK3CD/PIK3CGClass IB and Class ID PI3KPhosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit delta and gamma

Dual inhibition of the p110δ and p110γ catalytic subunits of Class I phosphoinositide 3-kinases (PI3Ks). This inhibition prevents the phosphorylation of phosphatidylinositol 4,5-bisphosphate (PIP2) into phosphatidylinositol 3,4,5-trisphosphate (PIP3), thereby blocking the activation of downstream signaling molecules like AKT and mTOR, which are critical for cell growth, survival, and migration (PubMed: 24567446).