F. Hoffmann-La Roche Ltd: Roche's giredestrant reduced risk of invasive disease recurrence or death by 30% in ER-positive early-stage breast cancer

• Giredestrant is the only oral SERD to show superior invasive disease-free survival in the adjuvant setting, marking the first significant endocrine therapy advance in over 20 years^1-3
• Transformational results support the potential of giredestrant to become a new standard-of-care for early-stage disease¹
• ER-positive breast cancer accounts for approximately 70% of breast cancer cases, and up to a third experience recurrence on or after adjuvant endocrine therapy treatment^4-7
• Data will be featured in an oral presentation at the 2025 San Antonio Breast Cancer Symposium and included in the official press programme

Basel, 10 December 2025 - Roche (SIX: RO, ROG; OTCQX: RHHBY) announced today positive data from the phase III lidERA Breast Cancer study evaluating investigational giredestrant as an adjuvant endocrine treatment for people with oestrogen receptor (ER)-positive, human epidermal growth factor receptor 2-negative, early-stage breast cancer.¹ At the pre-specified interim analysis, adjuvant giredestrant significantly reduced the risk of invasive disease recurrence or death by 30% (invasive disease-free survival [iDFS]) compared with standard-of-care endocrine therapy (SoC ET) (hazard ratio [HR]=0.70, 95% confidence interval [CI] 0.57-0.87, p=0.0014).¹ The lidERA results are being presented at the 2025 San Antonio Breast Cancer Symposium and are included in the official press programme.

"In early ER-positive breast cancer, challenges with disease recurrence and treatment adherence mean there is an urgent need for more effective, tolerable endocrine therapies," said Aditya Bardia, M.D., M.P.H, Director, Breast Oncology Program, Professor of Medicine at the David Geffen School of Medicine at University of California, Los Angeles (UCLA), Director of Translational Research Integration at the UCLA Health Jonsson Comprehensive Cancer Center, and lidERA principal investigator. "After almost 25 years, a new medicine - giredestrant - has demonstrated superiority over existing endocrine therapies in the curative setting, highlighting its potential as a new standard-of-care endocrine therapy for patients with breast cancer."

"The substantial efficacy observed with giredestrant in the lidERA trial underscores its potential to become a new standard-of-care endocrine therapy in ER-positive early-stage breast cancer, where the chance for cure is highest," said Levi Garraway, MD, PhD, Roche's Chief Medical Officer and Head of Global Product Development. "We look forward to sharing these results with health authorities around the world with the aim of bringing this new treatment option to patients as soon as possible."

At three years, 92.4% of patients in the giredestrant arm were alive and free of invasive disease versus 89.6% in the SoC ET arm.¹ The iDFS benefit was consistent across all clinically relevant subgroups.¹ Overall survival (OS) data were immature at the time of this analysis, but a clear positive trend was observed.¹ Follow-up for OS will continue to the next analysis. Giredestrant also demonstrated a 31% risk reduction of distant recurrence-free interval (HR=0.69, 95% CI 0.54-0.89) - another key secondary endpoint.¹ Giredestrant was well tolerated; adverse events were manageable and consistent with its known safety profile.¹

ER-positive breast cancer accounts for approximately 70% of breast cancer cases, and the majority are diagnosed in the early-stage.^4,5 Currently, up to a third of people eventually experience recurrence on or after adjuvant endocrine therapy treatment for early-stage breast cancer.^5-7 Additionally, many have to interrupt or stop treatment early due to safety or tolerability issues, thereby increasing the risk of death.^8,9 These limitations underscore the need for more effective and better-tolerated options that can enhance adherence and prevent or delay disease recurrence.

Giredestrant is the first and only oral selective oestrogen receptor degrader (SERD) to show superior iDFS in the adjuvant setting and lidERA is the second positive phase III readout for giredestrant following the evERA Breast Cancer results in the metastatic setting.^1,10 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).¹¹ 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.^1,10,11

Roche's extensive giredestrant clinical development programme 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, randomised, open-label, multicentre study evaluating the efficacy and safety of adjuvant giredestrant versus standard-of-care endocrine therapy in people with medium- or high-risk stage I-III oestrogen receptor-positive, human epidermal growth factor receptor 2-negative breast cancer.¹² Over 4,100 patients were enrolled in the study.¹²

The primary endpoint is invasive disease-free survival (iDFS) excluding unrelated cancers in other organs (second primary non-breast cancers).¹² Key secondary endpoints include overall survival, iDFS including second primary non-breast cancers, disease-free survival and safety.¹²

About giredestrant
Giredestrant is an investigational, oral, potent next-generation selective oestrogen receptor degrader and full antagonist.¹³

Giredestrant is designed to block oestrogen from binding to the oestrogen receptor, triggering its breakdown (known as degradation) and stopping or slowing down the growth of cancer cells.¹⁴

Giredestrant has an extensive clinical development programme 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 oestrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative early-stage breast cancer (lidERA Breast Cancer; NCT04961996 (https://clinicaltrials.gov/study/NCT04961996?cond=Breast%20Cancer&intr=Giredestrant&term=lidera&rank=1))¹²
• Giredestrant plus everolimus versus SoC ET plus everolimus in ER-positive, HER2-negative, locally advanced or metastatic breast cancer (evERA Breast Cancer; NCT05306340 (https://clinicaltrials.gov/study/NCT05306340))¹⁵
• 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 (https://clinicaltrials.gov/study/NCT04546009?cond=Breast%20Cancer&intr=Giredestrant&term=persevera&rank=1))¹⁶
• Giredestrant plus investigator's choice of a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor versus fulvestrant plus a CDK4/6 inhibitor in ER-positive, HER2-negative advanced breast cancer resistant to adjuvant endocrine therapy (pionERA Breast Cancer; NCT06065748 (https://clinicaltrials.gov/study/NCT06065748?cond=Breast%20Cancer&intr=Giredestrant&term=pionera&rank=1))¹⁷
• Giredestrant plus Phesgo (pertuzumab, trastuzumab, and hyaluronidase subcutaneous) versus Phesgo in ER-positive, HER2-positive locally advanced or metastatic breast cancer (heredERA Breast Cancer; NCT05296798 (https://clinicaltrials.gov/study/NCT05296798?cond=Breast%20Cancer&intr=Giredestrant&term=heredera&rank=1))¹⁸

About oestrogen 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.¹⁹ Breast cancer remains the number one cause of cancer-related deaths amongst women, and the second most common cancer type.²⁰

ER-positive breast cancer accounts for approximately 70% of breast cancer cases.⁴A defining feature of ER-positive breast cancer is that its tumour cells have receptors that attach to oestrogen, which can contribute to tumour growth.²¹

Despite treatment advances, ER-positive breast cancer remains particularly challenging to treat due to its biological complexity.²² Patients often face the risk of disease progression, treatment side effects and resistance to endocrine therapy.^5-9,22,23 There is an urgent need for more effective treatments that can delay clinical progression and reduce the burden of treatment on people's lives.^5,8,22,23

About Roche in breast cancer
Roche has been advancing breast cancer research for more than 30 years, and it continues to be a major focus of research and development. Our legacy began with the development of the first targeted therapy for human epidermal growth factor receptor 2-positive breast cancer, and we continue to push the boundaries of science to address the complexities of all breast cancer subtypes.

By leveraging our dual expertise in pharmaceuticals and diagnostics, we are dedicated to providing tailored treatment approaches and improving outcomes for every patient, from early to advanced stages of the disease. Together with our partners, we are relentlessly pursuing a cure, as we strive for a future where no one dies from breast cancer.

About Roche
Founded in 1896 in Basel, Switzerland, as one of the first industrial manufacturers of branded medicines, Roche has grown into the world's largest biotechnology company and the global leader in in-vitro diagnostics. The company pursues scientific excellence to discover and develop medicines and diagnostics for improving and saving the lives of people around the world. We are a pioneer in personalised healthcare and want to further transform how healthcare is delivered to have an even greater impact. To provide the best care for each person we partner with many stakeholders and combine our strengths in Diagnostics and Pharma with data insights from the clinical practice.

For over 125 years, sustainability has been an integral part of Roche's business. As a science-driven company, our greatest contribution to society is developing innovative medicines and diagnostics that help people live healthier lives. Roche is committed to the Science Based Targets initiative and the Sustainable Markets Initiative to achieve net zero by 2045.

Genentech, in the United States, is a wholly owned member of the Roche Group. Roche is the majority shareholder in Chugai Pharmaceutical, Japan.

For more information, please visit www.roche.com.

All trademarks used or mentioned in this release are protected by law.

References
[1] Bardia A, et al. Giredestrant vs standard-of-care endocrine therapy as adjuvant treatment for patients with estrogen receptor-positive, HER2-negative early breast cancer: Results from the global Phase III lidERA Breast Cancer trial. Presented at: San Antonio Breast Cancer Symposium.
[13] Martin M, et al. Giredestrant.
[16] ClinicalTrials.gov. A Study Evaluating the Efficacy and Safety of Giredestrant Combined With Palbociclib
Compared With Letrozole Combined With Palbociclib in Participants With Estrogen Receptor-Positive, HER2-
Negative Locally Advanced or Metastatic Breast Cancer.
[17] ClinicalTrials.gov. A Study to Evaluate Efficacy and Safety of Giredestrant Compared With Fulvestrant.
[18] ClinicalTrials.gov. A Study to Evaluate the Efficacy and Safety of Giredestrant in Combination With Phesgo
.
[19] World Health Organization. Breast Cancer [Internet; cited 2025 December]. Available from: https://www.who.int/news-room/fact-sheets/detail/breast-cancer.
[20] World Health Organization. Cancer Today [Internet; cited 2025 December]. Available from: https://gco.iarc.fr/today/en/dataviz/bars?mode=cancer&types=1&group_populations=1&sexes=2&key=asr&age_end=14.
[21] Cleveland Clinic. Estrogen Receptor-Positive Breast Cancer.
[22] Hanker A, et al. Overcoming Endocrine Resistance in Breast Cancer. Canc Cell. 2020;37(4):496-513.
[23] Basaran G, et al. Ongoing unmet needs in treating estrogen receptor-positive/HER2-negative metastatic
breast cancer. Cancer Treat Rev. 2018;63:144-55.

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