Roche reported positive Phase III results for giredestrant in the adjuvant setting, showing a statistically significant improvement in invasive disease‑free survival versus standard endocrine therapy in ER‑positive, HER2‑negative early breast cancer. The readout, disclosed at a preplanned interim analysis, marks one of the first late‑stage SERD successes in the adjuvant setting. Roche’s data drove investor and competitor reactions, boosting shares across peers developing oral SERDs and sharpening the field’s regulatory and commercial calculus. The result could expand giredestrant’s addressable population if regulators accept the interim analyses and safety profile. Companies with competing oral SERD programs will need to weigh longer or broader studies and potential label differences; payers will evaluate long‑term benefit versus established injections and cost implications.