PF-4989216 is an orally bioavailable broad-spectrum PI3K inhibitor (IC50s = 2, 142, 65, 1, and 110 nM for p110α, p110β, p110γ, p110δ, and VPS34, respectively). It inhibits the cell viability of small-cell lung cancer (SCLC) cells with a mutation in PIK3CA, blocking PI3K downstream signaling and inducing apoptosis. PF-4989216 prevents tumor growth of SCLC cells harboring PIK3CA mutation in mice.