A Study of Tersolisib for Advanced Breast Cancer with PIK3CA Genetic Change
This study is looking at a new treatment called Tersolisib (LY4064809/STX-478) for advanced breast cancer that has a specific genetic change (PIK3CA) and is hormone receptor-positive (HR+) and HER2-negative (HER2-). Tersolisib will be given along with other anti-cancer drugs like Ribociclib, Palbociclib, or Abemaciclib. The goal is to see how well this combination works as a first treatment and if it's safe. You might be able to join if you are 18 or older, have this type of breast cancer, and are willing to use contraception. The study will measure how many people respond to the treatment and how long they live without their cancer getting worse. You can stay in the study as long as the treatment is helping and you don't have severe side effects. The study plans to enroll 920 participants.
- Study design
- This is an interventional study, meaning participants will receive specific treatments. It plans to enroll 920 participants.
- What's involved
- Not specified in the trial record.
- Compensation
- Not stated in the trial record.
- Follow-up
- Participants will be followed for up to 5 years to see how long they respond to treatment and how long they live without their disease progressing.
AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.
NCT07174336
A Study of Tersolisib (LY4064809/STX-478) With Other Anti-Cancer Treatments in Participants With Advanced Breast Cancer With a Genetic Change (PIK3CA)
Recruiting
PHASE3Ages 18+InterventionalTreatmentEli Lilly and Company
~800 participants
Updated 2026-08-21 on ClinicalTrials.gov
What's tested:LY4064809PlaceboRibociclibPalbociclibAbemaciclibAnastrozole
At a glance
Recruiting sites
61 of 359 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
(Part 1): Overall Response Rate (ORR): Percentage of Participants with Confirmed Complete Response (CR) or Partial Response (PR)
Measured over Baseline through disease progression or death (Estimated up to 5 years)
+1 more outcome measured
Conditions
Where it's being run
359 sites across 56 statesSpain28
Japan25
Germany24
California22
China20
Brazil16
France16
Greece14
Study leadership
- Call 1-877-CTLILLY (1-877-285-4559) or 1-317-615-4559 Mon - Fri 8 AM - 8 PM Eastern time (UTC/GMT - 5 hours, EST) · STUDY_DIRECTOR · Eli Lilly and Company
Who to contact
Trial questions or participation questions: 1-877-CTLILLY (1-877-285-4559) or
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Do you actually qualify for this trial?
Add a private profile and we'll compare every criterion below against your situation — and tell you which ones are met, uncertain, or excluding.
Eligibility criteria
Inclusion
Are willing to follow contraception requirements. Contraceptive use by participants should be consistent with local regulations regarding the methods of contraception for those participating in clinical trials.
If assigned female at birth, pre-/peri- and postmenopausal status is allowed. Those with pre- or peri-menopausal status at study entry must agree to use ovarian function suppression with any locally approved gonadotropin-releasing hormone (GnRH) agonist.
If assigned male at birth with an estrogen receptor positive (ER+) breast cancer diagnosis, they must agree to use hormone suppression with a GnRH agonist.
Have histologically or cytologically confirmed breast cancer, defined as individuals with
locally advanced breast cancer not amenable to curative therapy (for example, surgery) or metastatic disease, and
hormone receptors (HR)+/human epidermal growth factor receptor 2 (HER2)- or HR+/HER low defined by American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) Guidelines
HR status: Documented ER+ and/or progesterone receptor-positive (PR+) tumor according to ASCO/CAP Guidelines, defined as greater than or equal to (≥)1 percent (%) of tumor cells stained positive based on the most recent tumor biopsy and assessed locally
HER status: immunohistochemistry score of 1+ or score of 2+ with a negative Fluorescence In Situ Hybridization (FISH) based on local results as defined in the ASCO/CAP Guidelines
Have evidence of an activating PIK3CA mutation, detected in tumor or blood samples using an appropriate assay.
Have measurable disease or non-measurable, evaluable bone disease
Part 1:
Received 0-2 prior systemic treatments for advanced breast cancer not amenable to curative therapy (for example, surgery) or metastatic disease.
Up to 1 of these prior systemic treatments may contain chemotherapy
Part 2:
Received 0 prior systemic treatment for advanced breast cancer not amenable to curative therapy (for example, surgery) or metastatic disease.
Individuals who are eligible are either
Population 1 (P1): Endocrine sensitive
newly diagnosed with advanced breast cancer (de novo)
participants with a history of HR+, HER2- EBC and did not receive SOC adjuvant ET
relapsed with documented evidence of progression greater than (\>)12 months from completion of (neo)adjuvant ET ± cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitor, or
Population 2 (P2): Endocrine resistant
relapsed with documented evidence of progression less than or equal to (≤)12 months of completing (neo)adjuvant ET ± CDK4/6 inhibitor.
if a CDK4/6 inhibitor was included as part of neoadjuvant or adjuvant therapy, progression event must be \>12 months since completion of CDK4/6 inhibitor portion of neoadjuvant or adjuvant therapy.
Exclusion
Have an established diagnosis of Type 1 diabetes mellitus or Type 2 diabetes mellitus with hemoglobin A1c (HbA1c) ≥8%, fasting blood glucose (FBG) ≥140 milligrams per deciliter (mg/dL) (7.7 millimoles per liter \[mmol/L\]), or requiring insulin.
Have inflammatory or metaplastic breast cancer.
History of leptomeningeal disease or carcinomatous meningitis.
Have known and untreated or active central nervous system (CNS) metastases. Exception: Asymptomatic brain or spinal metastases if treated by surgery, surgery plus radiotherapy, or radiotherapy alone with no evidence of radiographic progression or hemorrhage within at least 28 days before randomization and no requirement for anticonvulsants or systemic corticosteroids for at least 28 days before randomization.
Have received treatment with any local or systemic antineoplastic therapy or investigational anticancer agent within 14 days or 4 half-lives, whichever is longer, prior to randomization up to a maximum washout period of 28 days.
Have a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy (dose more than 10 milligrams \[mg\] daily of prednisone equivalent) or any other form of immunosuppressive therapy within 7 days prior to randomization.
Are pregnant, breastfeeding, or intend to become pregnant during the study or within 6 months of the last dose of study intervention and at least 2 years after the last dose of fulvestrant and/or CDK4/6 inhibitor after the final administration of study treatment.
Have active bacterial or fungal infection that is not recovered at randomization.
What this trial measures
- (Part 1): Overall Response Rate (ORR): Percentage of Participants with Confirmed Complete Response (CR) or Partial Response (PR)Baseline through disease progression or death (Estimated up to 5 years)
As determined by the investigator based on Response Evaluation Criteria in Solid Tumors (RECIST) v 1.1
- (Part 2): Progression-Free SurvivalBaseline to objective progression or death due to any cause (Estimated up to 5 years)
Investigator-assessed