Roche shares dip as oral breast cancer drug fails trial

Shares in Roche fell more than five percent after the Swiss drugmaker failed to show that its promising drug candidate giredestrant against a common form of breast cancer could help newly diagnosed patients.

Roche said on Monday that the phase III trial did not provide reliable evidence that using the drug in combination with Pfizer’s Ibrance as an initial treatment slowed disease progression compared with standard hormonal therapy plus Ibrance.

This marked a reversal of fortunes for the oral compound.

The Roche pill in 2025 boosted shares of Roche by reducing the risk of tumor recurrence in breast cancer patients who received the established initial treatment in a late-stage trial.

Giredestrant pill belongs to a class of drugs known as oral selective estrogen receptor degraders (SERDs) to fight tumors that grow in response to estrogen and account for 80 percent of all breast cancer cases.

The market opportunity has also attracted the attention of AstraZeneca, which is developing the rival compound camizestrant.