In an analysis of tumors from five clinical trials of early HER2-positive breast cancer treated with neoadjuvant HER2-directed therapy alone, an RNA-based assay combining both ERBB2 and the HER2-enriched intrinsic subtype allowed better identification of high anti-HER2 sensitivity compared to when either were used in isolation [6]. The gene discussed is ERBB2; the disease is breast carcinoma.