Roche giredestrant cuts progression risk 44% in breast cancer trial

Roche has reported that its investigational oral SERD giredestrant, combined with everolimus, significantly improved progression-free survival (PFS) in patients with oestrogen receptor-positive, HER2-negative locally advanced or metastatic breast cancer in the phase III evERA trial. Full results were published on 1 October in The New England Journal of Medicine.

In the intent-to-treat population, median PFS reached 8.8 months with giredestrant plus everolimus versus 5.5 months in the comparator arm of standard endocrine therapy plus everolimus, a hazard ratio of 0.56 (95% CI: 0.44–0.71, p<0.001), representing a 44% reduction in the risk of disease progression or death. The benefit was more pronounced in the ESR1-mutated subgroup, where median PFS extended to 10.0 months against 5.5 months in the control arm, a hazard ratio of 0.38 (95% CI: 0.27–0.54, p<0.001), equating to a 62% risk reduction. Overall survival data remain immature, though early trends favour the giredestrant arm in both populations.

Clinical significance

The trial enrolled patients who had progressed following treatment with a CDK4/6 inhibitor and endocrine therapy, a setting in which ESR1 mutations arise in up to 40% of cases and drive resistance to standard agents. Dr Erica L. Mayer, Medical Oncologist at Dana-Farber Cancer Institute, said the evERA data demonstrated that "the giredestrant combination significantly delayed disease progression, potentially offering a promising all-oral treatment option in a setting where there remains a need for additional treatments to improve patient outcomes."

The safety profile was described as manageable and consistent with the known profiles of each component. Notably, no photopsia was observed and bradycardia rates were low, addressing two adverse events that have historically complicated SERDs in the class.

Regulatory path and competitive landscape

The FDA has accepted Roche's New Drug Application for giredestrant in combination with everolimus for the ESR1-mutated locally advanced or metastatic indication, with a PDUFA goal date of 18 December 2026. A separate NDA for giredestrant as adjuvant treatment in early-stage ER-positive, HER2-negative breast cancer, based on the positive lidERA trial, carries a PDUFA date of 30 November 2026 under Priority Review.

Giredestrant enters a SERD field that has seen significant competitive activity. AstraZeneca's elacestrant received FDA approval in 2023 for ESR1-mutated metastatic breast cancer as monotherapy, while Merus, Relay Therapeutics and others are advancing next-generation oestrogen receptor-targeted agents. The evERA combination approach, pairing a SERD with the mTOR inhibitor everolimus, is differentiated from monotherapy SERD strategies and from the established CDK4/6 inhibitor backbone; however, combination tolerability and patient selection will be scrutinised by payers and prescribers when any approval is translated to routine practice.

HR-positive, HER2-negative breast cancer represents approximately 70% of all breast cancer cases globally, and the post-CDK4/6 inhibitor setting remains an area of active unmet need. With two positive phase III readouts now in hand, Roche is positioning giredestrant as a potential standard-of-care candidate across both early and advanced disease. Analysts and oncologists will watch the forthcoming PDUFA decisions closely, and full OS maturation in evERA will be the next critical data readout to confirm or extend the PFS signal.