SAR405 is a low-molecular-mass kinase inhibitor of PIK3C3/Vps34 (KD 1.5 nM) showing high selectivity and not be active up to 10 μM on class I and class II PI3Ks as well as on mTOR. SAR405 prevents autophagy and synergizes with MTOR (mechanistic target of rapamycin) inhibition in tumor cells.