Somatic mutations in four genes (PIK3CA, KRAS, BRAF, and EGFR) accounted for 76/89 (85 %) of genotype-matched trial enrollments: including PIK3CA for breast cancer (20/22); BRAF (5/18) and KRAS (9/18) for colorectal cancer; KRAS (9/18) and EGFR (7/18) for non-small cell lung cancer; and KRAS (14/22) and PIK3CA (7/22) for gynecological cancers. The gene discussed is PIK3CA; the disease is breast cancer.