On March 9, 2026 Genentech, a member of the Roche Group (SIX: RO, ROG; OTCQX: RHHBY), reported results from the Phase III persevERA Breast Cancer study evaluating investigational giredestrant in combination with palbociclib for people with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative, locally advanced or metastatic breast cancer. The study did not meet its primary objective of a statistically significant improvement in progression-free survival in the intent-to-treat population versus letrozole plus palbociclib, but a numerical improvement was observed. The adverse events for the giredestrant combination were manageable and consistent with the known safety profiles of each individual treatment.
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"While persevERA didn’t meet its primary objective, we are confident in the potential of giredestrant to become a new standard-of-care endocrine therapy in early and advanced ER-positive breast cancer," said Levi Garraway, M.D., Ph.D., chief medical officer and head of Global Product Development. "We believe there is a path forward for combining giredestrant with a CDK4/6 inhibitor in the adjuvant setting and we are conducting further studies. The efficacy demonstrated in evERA and lidERA provides clear validation of the clinical activity of giredestrant and reinforces the strength of our expanding clinical development program."
The giredestrant clinical development program is made up of distinct studies designed to reflect the specific disease biology of each stage of breast cancer. Genentech will continue to advance the clinical development program to identify the people with ER-positive breast cancer who can derive the greatest benefit from giredestrant.
Giredestrant Phase III clinical development program
Trial
Indication
Regimen
lidERA
Breast Cancer
Adjuvant ER+/HER2- breast cancer
Giredestrant vs. standard-of-care endocrine therapy (SoC ET)
persevERA Breast Cancer
1L ER+/HER2- metastatic breast cancer
(endocrine-sensitive)
Giredestrant + palbociclib vs. letrozole plus palbociclib
pionERA Breast Cancer
1L ER+/HER2- metastatic breast cancer
(endocrine-resistant)
Giredestrant + physician’s choice of CDK4/6 inhibitor vs. fulvestrant + physician’s choice of CDK4/6 inhibitor
evERA
Breast Cancer
2L+ ER+/HER2- metastatic breast cancer
Giredestrant + everolimus vs. SoC ET + everolimus
heredERA Breast Cancer
1L maintenance ER+/HER2+ metastatic breast cancer
Giredestrant + dual HER2 blockade vs. HER2 blockade
evERA was the first positive Phase III readout for giredestrant, followed by lidERA in the early-stage setting. The scientific rationale for lidERA was supported by prior results in the neoadjuvant setting, including the Phase II coopERA trial showing that giredestrant was superior to an aromatase inhibitor in reducing malignant cell division (Ki67 levels). This growing body of evidence underscores the potential of giredestrant to become a new standard-of-care endocrine therapy across ER-positive early-stage and advanced breast cancer.
persevERA is the first of two distinct Phase III studies in the first-line setting; the pionERA study of giredestrant in combination with physician’s choice of cyclin-dependent kinase (CDK)4/6 inhibitor in endocrine-resistant ER-positive, HER2-negative breast cancer is expected to readout in 2027.
The United States Food and Drug Administration (FDA) recently accepted the New Drug Application based on the evERA data. In the coming weeks, Genentech will submit the giredestrant Phase III lidERA data in early-stage breast cancer to the FDA.
The full results from persevERA will be presented at an upcoming medical meeting.
About the persevERA Breast Cancer study
persevERA Breast Cancer [NCT04546009] is a Phase III, randomized, double-blind, placebo-controlled, multicenter study evaluating the efficacy and safety of giredestrant plus palbociclib versus letrozole plus palbociclib as first-line treatment for people with estrogen receptor-positive, human epidermal growth factor receptor 2-negative, locally advanced or metastatic breast cancer. The study enrolled 992 patients globally.
The primary endpoint is investigator-assessed progression-free survival. Key secondary endpoints include overall survival, objective response rate, duration of response and safety.
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 (ER), 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 CDK4/6 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 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. In the U.S. and EU5, an estimated 273,000 people are diagnosed in the early-stage setting, 88,000 people are diagnosed in first-line and 106,000 in the second and third-line setting combined.
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. In the early-stage setting, up to a third of people eventually experience disease recurrence on or after adjuvant endocrine therapy treatment. Additionally, many have to interrupt or stop treatment early due to safety or tolerability issues, thereby increasing the risk of death. In advanced settings, resistance to endocrine therapy – particularly following treatment with cyclin-dependent kinase inhibitors – increases the risk of disease progression and is associated with poor outcomes.
There is an urgent need for more effective treatments that can delay clinical progression and reduce the burden of treatment on people’s lives.
(Press release, Genentech, MAR 9, 2026, View Source [SID1234663385])