While there is a general lack of consensus between studies involving PIK3CA mutant cell sensitivity to pan-Class I PI3K inhibition [31, 32, 33, 34, 35, 36], recent preclinical studies indicate that PIK3CA mutant cancer cells are indeed more sensitive to the p110α-specific inhibitors BYL719 (Novartis) and INK1117 (Millennium) [37, 38] and the ‘p110β-sparing’ p110α inhibitors GDC-0032 (Genentech) and CH5132799 (Chugai Pharmaceutical) [33, 39]. This evidence concerns the gene PIK3CB and cancer.