Bosmolisib

Bosmolisib is an orally bioavailable inhibitor of phosphoinositide 3-kinase delta (PI3-kinase subunit delta; PI3K-delta; PI3Kdelta) and DNA-dependent protein kinase (DNA-PK), with potential antineoplastic and immunomodulating activities. Upon oral administration, bosmolisib inhibits the activity of both PI3K-delta and DNA-PK. This prevents PI3K-mediated signaling pathways and may lead to the inhibition of cancer cell growth in PI3K-overexpressing tumor cells. Specifically, since PI3K regulates c-myc expression, inhibition of PI3K signaling may lead to a decrease in proliferation of c-myc-expressing tumor cells. Also, by inhibiting the activity of DNA-PK, bosmolisib interferes with the non-homologous end joining (NHEJ) process and prevents the repair of DNA double strand breaks (DSBs) caused by ionizing radiation or chemotherapeutic treatment. This increases chemo- and radiotherapy cytotoxicity by inhibiting the ability of tumor cells to repair damaged DNA. The PI3K pathway is upregulated in a variety of tumors and plays an important role in regulating cancer cell proliferation, growth, and survival. DNA-PK is activated upon DNA damage and plays a key role in repairing double-stranded DNA breaks. The enhanced ability of tumor cells to repair DSBs plays a major role in the resistance of tumor cells to chemo- and radiotherapy. In addition, bosmolisib is able to decrease Tregs and increase CD8 lymphocytes.