The CAPItello-291 trial demonstrated that capivasertib combined with fulvestrant significantly prolonged progression-free survival in patients with hormone receptor–positive, HER2–negative advanced breast cancer, particularly in those with PIK3CA, AKT1, or PTEN mutations.1) However, frequent adverse events such as diarrhea, rash, and hyperglycemia have been reported, with hyperglycemia occasionally progressing to DKA. The gene discussed is PIK3CA; the disease is Hyperglycemia.