Roche's giredestrant advances toward FDA review for ESR1-mutated breast cancer treatment

# Roche's Giredestrant Moves Toward FDA Review After Phase III Win in ESR1-Mutated Breast Cancer Roche [announced](https://www.globenewswire.com/news-release/2026/02/20/3241682/0/en/FDA-accepts-New-Drug-Application-for-Roche-s-giredestrant-in-ESR1-mutated-ER-positive-advanced-breast-cancer.html) that the US FDA has accepted a New Drug Application for giredestrant, an oral selective oestrogen receptor degrader (SERD), in combination with everolimus for adults with ER-positive, HER2-negative, *ESR1*-mutated locally advanced or metastatic breast cancer who have progressed on prior endocrine-based therapy. The giredestrant FDA filing, supported by the Phase III evERA Breast Cancer trial, which met both co-primary endpoints with a 62% reduction in the risk of disease progression or death in the *ESR1*-mutated population, marks a turning point for a molecule whose development trajectory has been uneven. Giredestrant is designed to block oestrogen from binding to the oestrogen receptor and trigger its degradation, functioning as a full antagonist — a mechanism intended to suppress tumour growth even when *ESR1* mutations render conventional endocrine therapies less effective. ## Trial specifics The [evERA Breast Cancer study](https://clinicaltrials.gov/study/NCT05306340) is a Phase III, randomised, open-label, multicentre trial comparing giredestrant plus everolimus against physician's choice of standard-of-care endocrine therapy plus everolimus in patients with ER-positive, HER2-negative locally advanced or metastatic breast cancer previously treated with a CDK4/6 inhibitor and endocrine therapy. The trial was enriched for patients carrying *ESR1* mutations above natural prevalence — a population that can represent up to 40% of patients in the post-CDK4/6 inhibitor setting. The co-primary endpoints were investigator-assessed progression-free survival (PFS) in both the intention-to-treat (ITT) population and the *ESR1*-mutated subgroup, defined as time from randomisation to disease progression or death from any cause. In the *ESR1*-mutated population, median PFS was 9.99 months for the giredestrant everolimus combination versus 5.45 months in the comparator arm (stratified hazard ratio 0.38, 95% CI: 0.27–0.54, p<0.0001). In the ITT population, median PFS was 8.77 months versus 5.49 months (HR 0.56, 95% CI: 0.44–0.71, p<0.0001). Overall survival data were immature at the time of analysis, though a positive trend was observed in both the ITT population (HR 0.69, 95% CI: 0.47–1.00, p=0.0473) and the *ESR1*-mutated population (HR 0.62, 95% CI: 0.38–1.02, p=0.0566). Follow-up for OS will continue to the next planned analysis. Adverse events were described as manageable and consistent with the known safety profiles of the individual agents. No photopsia — a visual side effect observed with some other agents in the oral SERD class — was reported. The US FDA has set a Prescription Drug User Fee Act (PDUFA) target action date of 18 December 2026. If approved, giredestrant plus everolimus would be the first oral SERD combination cleared for use in the post-CDK4/6 inhibitor setting. Roche said it is also using evERA data to support filing submissions to other global health authorities. Levi Garraway, Roche's Chief Medical Officer, stated that the filing acceptance "marks a first step towards establishing the giredestrant combination as a new standard of care in this population." The company also indicated that it plans to submit the Phase III lidERA data for giredestrant in early-stage breast cancer to the FDA and other agencies in the coming weeks, and that a readout from the persevERA trial in first-line ER-positive advanced breast cancer is expected in H1 2026. ## Giredestrant FDA filing in context: mechanism, designations, and the ESR1 mutation problem Giredestrant was discovered and developed internally at Genentech, Roche's US biotechnology subsidiary, and Roche retains full global rights. The molecule is an oral, next-generation SERD that binds the oestrogen receptor, blocks oestrogen-driven transcriptional activity, and triggers receptor degradation. This dual mechanism — antagonism and degradation — is designed to be effective against both wild-type ER and the ligand-binding-domain mutations in *ESR1* that frequently [emerge under selective pressure](https://app.allsci.com/article/W4306149937) from aromatase inhibitors and CDK4/6 inhibitor–based regimens. The addition of everolimus, an mTOR inhibitor already approved by the US FDA for use with exemestane in HR-positive advanced breast cancer, targets the [PI3K/AKT/mTOR signalling axis](https://app.allsci.com/article/W3045706461) — a pathway frequently activated in endocrine-resistant ER-positive disease. The rationale for the combination is to suppress the ER transcriptional programme while simultaneously dampening a compensatory growth-factor signalling route that tumours can exploit to evade endocrine therapy. Giredestrant holds US FDA Breakthrough Therapy Designation, granted in December 2021 for monotherapy in *ESR1*-mutated ER-positive, HER2-negative metastatic breast cancer, and Fast Track Designation for the neoadjuvant setting in ER-positive, HER2-negative early breast cancer. The molecule remains unapproved in all jurisdictions globally. Its path to this Roche giredestrant NDA filing has not been straightforward: in November 2023, the persevERA Phase III trial failed to meet its primary PFS endpoint when giredestrant plus palbociclib was compared against letrozole plus palbociclib in the first-line advanced setting. The evERA result, particularly the pronounced benefit in *ESR1*-mutated patients, has refocused the programme on a biomarker-selected strategy in the post-CDK4/6 inhibitor space. ER-positive breast cancer accounts for approximately 70% of all breast cancer diagnoses. While CDK4/6 inhibitors combined with endocrine therapy have become standard first-line treatment for advanced disease, resistance develops in most patients, and ESR1 mutation breast cancer treatment options after progression remain limited. The current standard in the post-CDK4/6 inhibitor setting often involves fulvestrant (an injectable SERD) or chemotherapy, neither of which specifically addresses the biology of *ESR1*-mutated disease with an oral, targeted degrader approach. The oral SERD class has attracted substantial investment from multiple companies. Key competitors include: * **Elacestrant (Orserdu)**, developed by Stemline Therapeutics (a Menarini Group company), is the only oral SERD currently approved by the US FDA, granted in January 2023 for ER-positive, HER2-negative, *ESR1*-mutated advanced or metastatic breast cancer after at least one line of endocrine therapy. Approval was based on the [Phase III EMERALD trial](https://app.allsci.com/article/W4401204768), which showed a PFS benefit over standard-of-care endocrine therapy, though the magnitude of benefit in the overall population was modest. Elacestrant is approved as monotherapy, not in combination with an mTOR inhibitor, which distinguishes it from the giredestrant everolimus regimen. * **Camizestrant**, developed by AstraZeneca, is an oral SERD in Phase III development. The [SERENA-6 trial](https://app.allsci.com/article/W4366236771) is specifically evaluating camizestrant in patients with *ESR1* mutations detected during first-line CDK4/6 inhibitor therapy, and earlier Phase II data from [SERENA-2](https://app.allsci.com/article/W4379285547) showed activity in the post-CDK4/6 inhibitor setting. AstraZeneca has positioned camizestrant across multiple lines of therapy, including a first-line combination strategy. * **Imlunestrant (LY3484356)**, developed by Eli Lilly, is being evaluated in the [Phase III EMBER-3 trial](https://app.allsci.com/article/W4410803265) in advanced ER-positive breast cancer, including as monotherapy and in combination with abemaciclib. Earlier [Phase Ia/Ib data](https://app.allsci.com/article/W4281829342) demonstrated single-agent activity, and the programme spans both monotherapy and combination approaches. * **Lasofoxifene**, developed by US-based Sermonix Pharmaceuticals, is a selective oestrogen receptor modulator with activity against *ESR1*-mutant tumours. The [Phase III ELAINE 3 trial](https://app.allsci.com/article/W4409398128) is evaluating lasofoxifene in combination with abemaciclib specifically in *ESR1*-mutated ER-positive, HER2-negative metastatic breast cancer. Earlier [Phase II ELAINE 1 data](https://app.allsci.com/article/W4389516746) showed signals of activity in this biomarker-defined population. The evERA data position giredestrant breast cancer treatment as potentially differentiated in two respects: the magnitude of PFS benefit in the *ESR1*-mutated population (HR 0.38) exceeds what has been reported for elacestrant monotherapy in EMERALD, and the combination with everolimus targets both the ER axis and the mTOR pathway simultaneously. However, cross-trial comparisons carry well-known limitations, and the open-label design of evERA introduces potential for assessment bias in the investigator-assessed PFS endpoint. Whether the OS trend matures into a confirmed survival benefit will be a factor in how physicians and regulators weigh the data against existing and emerging options. The PDUFA date of 18 December 2026 will determine whether giredestrant becomes the second oral SERD — and the first oral SERD combination — approved for ER-positive advanced breast cancer in the post-CDK4/6 inhibitor setting. --- Spot something wrong? [Report an issue with this article](https://newsgen-prod.reframedata.com/feedback/giredestrant-fda-review-roches-advances-toward)