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Phase 3 Study for PIK3CA-mutant Breast Cancer

This study is for people with hormone receptor-positive (HR+), HER2-negative (HER2-) breast cancer that has spread (metastatic) or is locally advanced, and has a specific gene change called PIK3CA mutation. It's for those whose cancer has progressed after treatment with a CDK4/6 inhibitor. The study is comparing two drug combinations: RLY-2608 plus fulvestrant, and capivasertib plus fulvestrant. Researchers want to see which combination is more effective at preventing the cancer from growing or spreading. The study plans to enroll 540 participants and will measure how long people live without their cancer getting worse (progression-free survival) for up to approximately 77 months. You must be at least 18 years old and have an ECOG performance status of 0-1, meaning you are fully active or can perform light work.

Study design
This is a global, multi-center, open-label (meaning everyone knows which treatment they are receiving), randomized Phase 3 study comparing two different drug combinations. It plans to enroll 540 participants.
What's involved
You would take RLY-2608 or Capivasertib orally daily or intermittently, and receive Fulvestrant intramuscularly on a 28-day treatment cycle. Specific details about visits or other procedures are not provided.
Compensation
Not stated in the trial record.
Follow-up
Participants will be followed to measure progression-free survival for up to approximately 77 months.

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NCT06982521

Phase 3 Study of RLY-2608 + Fulvestrant vs Capivasertib + Fulvestrant as Treatment for Locally Advanced or Metastatic PIK3CA-mutant HR+/HER2- Breast Cancer

Recruiting
PHASE3Ages 18+InterventionalTreatment
Relay Therapeutics, Inc.
~540 participants
Updated 2026-08-05 on ClinicalTrials.gov
What's tested:ZovegalisibCapivasertibFulvestrant

At a glance

Recruiting sites
222 of 222 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Progression-Free Survival (PFS) within the overall and kinase population by blinded independent central review (BICR)
Measured over The time from date of randomization until radiographic progression per RECIST v1.1, or death due to any cause, up to approximately 77 months

Conditions

PIK3CA Mutation
HER2- Negative Breast Cancer
Hormone Receptor Positive Tumor
Breast Cancer
Metastatic Breast Cancer
Advanced Breast Cancer

Explore related trials

Breast CarcinomaPIK3CA Gene

Where it's being run

222 sites across 54 states
Spain22
France19
Brazil16
Italy16
Belgium9
South Korea9
California8
Argentina8

Who to contact

Relay Therapeutics, Inc
[email protected]
617-322-0731
Email the study team

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Eligibility criteria

Inclusion

Patient has ECOG performance status of 0-1
One or more known primary oncogenic PIK3CA mutation(s)
Adult females, pre- and/or post-menopausal, and adult males. Pre-menopausal (and peri-menopausal) women can be enrolled if amenable to treatment with a gonadotropin-releasing hormone (GnRH) agonist. Patients are to have commenced treatment with a GnRH agonist at least 2 weeks prior to randomization and must be willing to continue on it for the duration of the study.
Histologically or cytologically confirmed diagnosis of HR+/HER2- locally advanced or metastatic breast cancer (ABC) with radiological or objective evidence of recurrence or progression; locally advanced disease must not be amenable to resection with curative intent
Measurable disease per RECIST v1.1 or evaluable bone-only disease.
Must have radiological evidence of progression on or after previous treatment for HR+/HER2- ABC with:

Exclusion

Prior treatment with any of the following:
Type 1 diabetes, or Type 2 diabetes requiring antihyperglycemic medication, or fasting plasma glucose ≥ 140 mg/dL (7.8 mmol/L), or glycosylated hemoglobin (HbA1c) ≥7.0% (≥ 53 mmol/mol).
Clinically significant, uncontrolled cardiovascular disease
Any factors that increase the risk of QTc prolongation or risk of arrhythmic events
Known active uncontrolled or symptomatic CNS metastases associated with progressive neurological symptoms or requiring ongoing corticosteroids or anticonvulsants for symptomatic control
Past medical history of interstitial lung disease, drug-induced interstitial lung disease, radiation pneumonitis which required steroid treatment, or any evidence of clinically active interstitial lung disease
History of hypersensitivity to fulvestrant or drugs in a similar class as fulvestrant, zovegalisib, or capivasertib, including their excipients
Known activating AKT mutations, loss-of-function PTEN mutations, or loss of PTEN expression resulting in oncogenic pathway activation downstream of PI3K

What this trial measures

  • Progression-Free Survival (PFS) within the overall and kinase population by blinded independent central review (BICR)The time from date of randomization until radiographic progression per RECIST v1.1, or death due to any cause, up to approximately 77 months