183P Efficacy and safety of tenalisib, a PI3K δ/γ and SIK3 inhibitor in patients with locally advanced or metastatic breast cancer: Initial results from a phase II study

Hyperactivation of PI3K pathway in breast cancer is implicated in malignant transformation, progression, and resistance to endocrine therapy. Salt Inducible Kinase- 3 (SIK3) is highly expressed in breast cancer and elevated SIK3 is shown to contribute to tumorigenesis. Tenalisib (RP6530), a PI3K δ/γ and SIK3 inhibitor has been evaluated in patients with haematological malignancies and demonstrated encouraging activity in T-cell lymphoma. Tenalisib’s major metabolite (IN0385) shows potent SIK3 inhibition Preclinical studies in breast cancer cell lines have demonstrated that tenalisib potentiates activity of taxol and doxorubicin.