-At interim analysis, giredestrant demonstrated a statistically significant and clinically meaningful benefit versus standard-of-care endocrine monotherapy-

-These unprecedented results support its potential as a new standard-of-care endocrine therapy in the early-stage setting-

-Data to be presented at an upcoming medical meeting and shared with health authorities around the world-

-lidERA is the second positive Phase III readout for giredestrant following evERA presented at ESMO 2025-

Genentech, a member of the Roche Group (SIX: RO, ROG; OTCQX: RHHBY), announced today positive Phase III results from the lidERA Breast Cancer study evaluating investigational giredestrant as an adjuvant endocrine treatment for people with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative, early-stage breast cancer. The study met its primary endpoint at a pre-planned interim analysis, showing a statistically significant and clinically meaningful improvement in invasive disease-free survival with giredestrant versus standard-of-care endocrine therapy. lidERA is the first Phase III trial of a selective estrogen receptor degrader (SERD) to demonstrate a significant benefit in the adjuvant setting. The majority of breast cancer cases are diagnosed at an early stage.

“Today’s results underscore the potential of giredestrant as a new endocrine therapy of choice for people with early-stage breast cancer, where there is a chance for cure,” said Levi Garraway, M.D., Ph.D., Genentech’s chief medical officer and head of Global Product Development. “Given that ER-positive breast cancer accounts for approximately 70% of cases diagnosed, these findings – together with recent data in the advanced ER-positive setting – suggest that giredestrant has the potential to improve outcomes for many people with this disease.”

Overall survival data were immature at the time of interim analysis, but a clear positive trend was observed. Giredestrant was well tolerated and adverse events were consistent with its known safety profile, with no unexpected safety findings observed. Data from lidERA will be presented at an upcoming medical meeting and shared with health authorities with the aim of bringing this potential treatment option to patients around the world.

ER-positive breast cancer accounts for approximately 70% of breast cancer cases. Currently, up to a third of people eventually experience recurrence on or after adjuvant endocrine therapy treatment for early-stage breast cancer. Additionally, many have to interrupt or stop treatment early due to safety or tolerability issues, thereby increasing the risk of death. These limitations underscore the need for more effective and better-tolerated options that can enhance adherence and prevent or delay disease recurrence.

lidERA is the second positive Phase III readout for giredestrant following evERA Breast Cancer, which was presented at the European Society for Medical Oncology Congress 2025. The scientific rationale for lidERA was supported by prior results in the neoadjuvant setting, including the coopERA trial showing that giredestrant was superior to an aromatase inhibitor in reducing malignant cell division (Ki67 levels). This growing body of evidence supports the potential of giredestrant to meaningfully improve outcomes compared with standard-of-care endocrine therapy across ER-positive early-stage and advanced breast cancer.

Genentech’s extensive giredestrant clinical development program spans multiple treatment settings and lines of therapy, reflecting our commitment to deliver innovative medicines to as many people with ER-positive breast cancer as possible.

About the lidERA Breast Cancer study

lidERA Breast Cancer [NCT04961996] is a Phase III, randomized, open-label, multicenter study evaluating the efficacy and safety of giredestrant versus standard-of-care endocrine therapy in people with medium- or high-risk stage I-III estrogen receptor-positive, human epidermal growth factor receptor 2-negative breast cancer. Over 4,100 patients were enrolled in the study.

The primary endpoint is invasive disease-free survival (iDFS) excluding unrelated cancers in other organs (second primary non-breast cancers). Key secondary endpoints include overall survival, iDFS including second primary non-breast cancers, disease-free survival and safety.

About estrogen receptor (ER)-positive breast cancer

Globally, the burden of breast cancer continues to grow, with 2.3 million women diagnosed and 670,000 dying from the disease every year. Breast cancer remains the number one cause of cancer-related deaths amongst women, and the second most common cancer type.

ER-positive breast cancer accounts for approximately 70% of breast cancer cases. A defining feature of ER-positive breast cancer is that its tumor cells have receptors that attach to estrogen, which can contribute to tumor growth.

Despite treatment advances, ER-positive breast cancer remains particularly challenging to treat due to its biological complexity. Patients often face the risk of disease progression, treatment side effects and resistance to endocrine therapy. There is an urgent need for more effective treatments that can delay clinical progression and reduce the burden of treatment on people’s lives.

About giredestrant

Giredestrant is an investigational, oral, potent next-generation selective estrogen receptor degrader and full antagonist.

Giredestrant is designed to block estrogen from binding to the estrogen receptor, triggering its breakdown (known as degradation) and stopping or slowing down the growth of cancer cells.

Giredestrant has an extensive clinical development program and is being investigated in five company-sponsored Phase III clinical trials that span multiple treatment settings and lines of therapy to benefit as many people as possible:

• Giredestrant versus standard-of-care endocrine therapy (SoC ET) as adjuvant treatment in ER-positive, human epidermal growth factor receptor 2 (HER2)-negative early-stage breast cancer (lidERA Breast Cancer; NCT04961996)
• Giredestrant plus everolimus versus SoC ET plus everolimus in ER-positive, HER2-negative, locally advanced or metastatic breast cancer (evERA Breast Cancer; NCT05306340)
• Giredestrant plus palbociclib versus letrozole plus palbociclib in ER-positive, HER2-negative, endocrine-sensitive, recurrent locally advanced or metastatic breast cancer (persevERA Breast Cancer; NCT04546009)
• Giredestrant plus investigator’s choice of a cyclin-dependent kinase (CDK) 4/6 inhibitor versus fulvestrant plus a CDK 4/6 inhibitor in ER-positive, HER2-negative advanced breast cancer resistant to adjuvant endocrine therapy (pionERA Breast Cancer; NCT06065748)
• Giredestrant plus dual HER2 blockade versus dual HER2 blockade in ER-positive, HER2-positive locally advanced or metastatic breast cancer (heredERA Breast Cancer; NCT05296798)

About Genentech in Breast Cancer

Genentech has been advancing breast cancer research for more than 30 years with the goal of helping as many people with the disease as possible. Our medicines, along with companion diagnostic tests, have contributed to bringing breakthrough outcomes in multiple types of breast cancers. As our understanding of breast cancer biology rapidly improves, we are working to identify new biomarkers and approaches to treatment for other subtypes of the disease, including estrogen receptor-positive breast cancer, which is a form of hormone receptor-positive breast cancer, the most prevalent type of all breast cancers.

About Genentech

Founded nearly 50 years ago, Genentech is a leading biotechnology company that discovers, develops, manufactures and commercializes medicines to treat patients with serious and life-threatening medical conditions. The company, a member of the Roche Group, has headquarters in South San Francisco, California. For additional information about the company, please visit http://www.gene.com.

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