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Study of inavolisib, palbociclib and fulvestrant in patients with PIK3CA-mutated, hormone receptor-positive, HER2-negative advanced or metastatic breast cancer

Verified siteRegistered drugNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study focuses on advanced breast cancer that is hormone receptor-positive and HER2-negative with a specific genetic change called PIK3CA mutation. The cancer in this study has either spread to other parts of the body (metastatic) or is locally advanced, meaning it has grown into nearby tissues but cannot be cured with surgery.

The study tests a combination of three medications: inavolisib, palbociclib, and fulvestrant. Some patients will receive all three active medications, while others will receive palbociclib and fulvestrant plus a placebo instead of inavolisib. The purpose is to determine if adding inavolisib to the combination of palbociclib and fulvestrant helps to slow down the growth of cancer.

During the study, patients will take inavolisib and palbociclib as tablets by mouth, while fulvestrant is given as an injection into the muscle. The treatment can continue for up to 96 months, depending on how well it works and how well it is tolerated. Throughout the study, doctors will monitor patients' health and perform regular assessments to check how the cancer responds to treatment.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial treatment assignment

    You will be randomly assigned to one of two treatment groups:

    Group 1: inavolisib + palbociclib + fulvestrant

    Group 2: placebo + palbociclib + fulvestrant

  2. Step 2

    Medication administration

    Palbociclib: Take tablets by mouth daily

    Inavolisib or placebo: Take tablets by mouth daily

    Fulvestrant: Receive intramuscular injections at scheduled appointments

  3. Step 3

    Regular monitoring

    Regular health checks including:

    Physical examinations

    Blood tests to check laboratory values

    Heart monitoring through ECG tests

    Measurement of vital signs

  4. Step 4

    Disease assessment

    Regular imaging tests to check how the disease responds to treatment

    Assessment of cancer progression using standard measurement criteria

    Evaluation of treatment response

  5. Step 5

    Side effect monitoring

    Regular assessment of any side effects

    Recording of any new symptoms or health changes

    Monitoring of pain levels

    Assessment of physical function and daily activities

  6. Step 6

    Blood sampling

    Blood samples will be collected at specified times to measure drug levels in your body

    Samples will check levels of inavolisib, palbociclib, and fulvestrant

  7. Step 7

    Study completion

    Treatment continues until disease progression or study end

    Final health assessment and follow-up tests

    The study is expected to continue until September 2030

Who can join the trial?

9 criteria

  • You must have a confirmed diagnosis of breast cancer that is hormone receptor-positive (HR+) and HER2-negative (these are specific proteins found on breast cancer cells that affect how the cancer grows)
  • Your cancer must be either:
    • Spread to other parts of the body (metastatic), or
    • Locally advanced (spread to nearby tissues) and cannot be cured with surgery
    • You must test positive for specific changes (mutations) in the PIK3CA gene through designated testing methods
    • Your disease must have:
      • Gotten worse during hormone therapy treatment, or
      • Gotten worse within 12 months after completing hormone therapy with either an aromatase inhibitor or tamoxifen (medications that block hormone effects on cancer)
      • Your cancer must be measurable using standard imaging criteria (RECIST v1.1)
      • You can be either male or female
      • You must be an adult (age 18 or older)

Who cannot join the trial?

12 criteria

  • Previous treatment with any PI3K inhibitor (medications that block specific enzymes involved in cell growth)
  • Active brain metastases (cancer that has spread to the brain) or brain disease requiring treatment
  • History of type 1 diabetes or uncontrolled type 2 diabetes (blood sugar levels not well managed)
  • Significant heart conditions including:
    • Unstable heart disease
    • Heart attack within the past 6 months
    • Uncontrolled high blood pressure
    • Current or recent (within 14 days) use of medications that may interact with study drugs
    • Active autoimmune disease (condition where immune system attacks healthy cells) requiring systemic treatment
    • Serious infections requiring treatment, including active hepatitis B, hepatitis C, or HIV
    • Known allergies or severe reactions to study medications or their components
    • Pregnancy or breastfeeding
    • Any other medical conditions that the study doctor determines could make participation unsafe
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Investigated drugs

Inavolisib is a new investigational medication that targets specific mutations in breast cancer cells, particularly those with PIK3CA mutations. It works by blocking certain signals that cancer cells use to grow and spread. Palbociclib is a medication that works by blocking specific proteins (CDK4/6) that help cancer cells multiply. It is commonly used in treating hormone receptor-positive breast cancer to slow down cancer growth. Fulvestrant is a hormone therapy medication that blocks and degrades estrogen receptors in breast cancer cells. It is used to treat hormone receptor-positive breast cancer by preventing estrogen from stimulating cancer growth. The combination of these three medications is being studied to determine if they work better together than just using palbociclib and fulvestrant with a placebo in treating advanced breast cancer that has specific genetic characteristics.

What is already known about the treatment

  • Inavolisib

    An investigational oral medication being studied for treating HR-positive/HER2-negative breast cancer with PIK3CA mutations. It works by inhibiting the PIK3CA pathway, which is commonly mutated in breast cancer cells, helping to slow down or stop cancer growth. This targeted therapy is currently being evaluated in Phase III clinical trials in combination with palbociclib and fulvestrant.

  • Palbociclib

    An oral medication that works as a selective inhibitor of cyclin-dependent kinases (CDK) 4 and 6, which are important for cell division. It is approved for treating hormone receptor-positive, HER2-negative advanced breast cancer in combination with hormone therapy. The medication helps to slow down cancer growth by blocking cell cycle progression.

  • Fulvestrant

    An injectable hormone therapy that works as a selective estrogen receptor degrader (SERD). It is administered through intramuscular injection and blocks the action of estrogen on cancer cells by binding to and degrading estrogen receptors. This medication is commonly used in treating hormone receptor-positive metastatic breast cancer, particularly in patients whose disease has progressed after other hormonal treatments.

Investigated diseases

  • Hormone Receptor-Positive (HR+)/HER2-Negative Breast Cancer

    A type of breast cancer that grows in response to hormones estrogen and/or progesterone but lacks excess HER2 protein. This cancer begins when abnormal cells in breast tissue start growing uncontrollably. It can develop from early stages to become locally advanced, meaning it has spread to nearby tissues or lymph nodes. In metastatic stage, the cancer spreads beyond the breast to distant parts of the body. Some cases of this cancer have mutations in the PIK3CA gene, which can affect how the cancer grows and responds.

  • PIK3CA-Mutated Breast Cancer

    A specific subtype of breast cancer characterized by mutations in the PIK3CA gene. This genetic alteration affects the PI3K signaling pathway, which plays a role in cell growth and survival. The mutation can occur in various stages of breast cancer and influences how the cancer cells multiply and spread. This particular mutation is found in approximately 40% of all hormone receptor-positive breast cancers.

Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-505812-39-00Protocol codeWO41554Estimated enrolment324 patientsSponsorF. Hoffmann-La Roche AG

sourced from the EU Clinical Trials Register and site verification

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