evERA: giredestrant plus everolimus nearly doubled progression-free survival in ESR1-mutated disease after CDK4/6

Design

Phase 3, open-label, randomised trial

Population

373 patients with ER+/HER2- advanced breast cancer after CDK4/6 inhibitor

Primary outcome

Investigator-assessed progression-free survival (ESR1-mutated, then overall)

Effect

ESR1-mutated: 10.0 vs 5.5 months, HR 0.38 (0.27-0.54); overall HR 0.56 (0.44-0.71)

The evERA trial, published in NEJM on 1 October 2026, randomised 373 patients with ER-positive, HER2-negative advanced breast cancer that had progressed after a CDK4/6 inhibitor plus endocrine therapy. They received oral giredestrant, an oral selective oestrogen receptor degrader, plus everolimus, or standard endocrine therapy (exemestane, fulvestrant or tamoxifen) plus everolimus.

In 207 patients with ESR1-mutated tumours, median progression-free survival was 10.0 against 5.5 months (HR 0.38, 95% CI 0.27 to 0.54). In the whole population it was 8.8 against 5.5 months (HR 0.56, 0.44 to 0.71). Adverse events were similar between arms, dominated by everolimus effects: stomatitis in nearly half, diarrhoea and anaemia.

The benefit is concentrated in ESR1-mutated disease, which makes testing at progression decisive. This is an open-label, industry-funded trial with progression-free survival as the endpoint; overall survival data are awaited, and giredestrant's regulatory status should be checked locally.

• Test for ESR1 mutation at progression on endocrine therapy, ideally on circulating tumour DNA.
• Expect the largest gain from an oral degrader-based combination in ESR1-mutated tumours.
• Plan stomatitis prevention when starting any everolimus combination.
• Check local availability; giredestrant's approval status varies by country.
• Discuss that overall survival benefit has not yet been shown.

Why it matters

It gives an all-oral second-line option and reinforces that ESR1 status should shape the choice.

Don't overread it

Progression-free survival only, in an open-label trial; overall survival is not yet reported.

The statistics, in plain English

A hazard ratio of 0.38 means the rate of progression or death was about 60% lower in ESR1-mutated disease. The overall-population effect (HR 0.56) is diluted by patients without the mutation, where the gain was smaller.

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