SAR260301 is potent, orally bioavailable and selective Class I phosphatidylinositol-3-kinase (PI3K)β specific inhibitor with an IC50 of 52 nM for PI3Kβ. SAR260301 is being investigated for the treatment of PTEN-deficient tumors. SAR260301 displayed improved physicochemical and in vitro pharmacokinetic properties. SAR260301 demonstrated significant in vivo activity in a UACC-62 xenograft model in mice, warranting further preclinical investigation.