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Study of OP-1250 for Treating Advanced or Metastatic ER+, HER2- Breast Cancer in Patients After Endocrine and CDK4/6 Inhibitor Therapy

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 clinical trial is focused on studying a type of breast cancer known as ER-positive, HER2-negative advanced or metastatic breast cancer. This type of cancer has spread beyond the breast and is not responsive to certain hormone therapies. The study will compare a new treatment called OP-1250, also known as Palazestrant, with standard treatments that are currently used for this type of cancer. The standard treatments include medications such as Fulvestrant, Goserelin, Anastrozole, Exemestane, and Letrozole. These medications work in different ways to help manage the cancer.

The purpose of the study is to evaluate the safety of OP-1250 and to see how well it works compared to the standard treatments. Participants in the study will receive either OP-1250 or one of the standard treatments. OP-1250 is taken as a tablet by mouth, while some of the standard treatments are given as injections. The study will last for a period of up to 42 days, during which the effects of the treatments will be monitored.

Throughout the study, doctors will closely observe participants to ensure their safety and to gather information on how the treatments affect the cancer. This includes checking for any side effects and measuring how the cancer responds to the treatment. The information collected will help determine if OP-1250 could be a better option for treating this type of breast cancer in the future.

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

    Joining the study

    Upon joining the study, participants will be informed about the trial's purpose and procedures. Consent will be obtained to ensure understanding and agreement to participate.

  2. Step 2

    Initial assessment

    Participants will undergo an initial assessment to confirm eligibility. This includes evaluating medical history, current health status, and previous treatments for breast cancer.

  3. Step 3

    Treatment assignment

    Participants will be randomly assigned to receive either OP-1250 monotherapy or standard care treatment. The standard care may include medications such as fulvestrant, anastrozole, exemestane, or letrozole.

  4. Step 4

    Medication administration

    For those receiving OP-1250, the medication will be administered orally at doses of 90 mg or 120 mg. The frequency and duration will be determined by the study protocol.

    Standard care medications will be administered according to their respective guidelines, which may include oral or intramuscular routes.

  5. Step 5

    Regular monitoring

    Participants will have regular check-ups to monitor health status, side effects, and treatment effectiveness. This includes blood tests, imaging studies, and other necessary evaluations.

  6. Step 6

    Safety and effectiveness evaluation

    The safety and effectiveness of the treatment will be assessed through various measures, including side effects, disease progression, and overall health outcomes.

  7. Step 7

    Completion of study participation

    Upon completion of the study, participants will undergo a final assessment to evaluate the overall impact of the treatment. Long-term follow-up may be conducted to gather additional data.

Who can join the trial?

8 criteria

  • Adult female or male participants can join the study.
  • Participants must have **ER+, HER2-** breast cancer that has spread to other parts of the body or is locally advanced and cannot be cured with current treatments.
  • The cancer must be **evaluable**, meaning it can be measured or is present only in the bones.
  • Participants should have previously received a **CDK4/6 inhibitor** along with **endocrine therapy** for advanced cancer. They may have also had one additional round of endocrine therapy alone.
  • Participants must have an **ECOG performance status** of 0 or 1, which means they are fully active or have some symptoms but do not need bed rest.
  • Participants need to have adequate blood, liver, and kidney function.
  • Female participants can be at any stage of menopause: before, during, or after.
  • Male participants and female participants who are pre- or peri-menopausal must agree to take a **GnRH (LHRH) agonist**, a type of medication that affects hormone levels.

Who cannot join the trial?

4 criteria

  • Patients who have not been diagnosed with ER+, HER2- metastatic breast cancer after receiving treatment with hormone therapy and a type of medication called CDK 4/6 inhibitor. This is a specific type of breast cancer that has spread to other parts of the body.
  • Patients who are not within the specified age range for the study.
  • Patients who do not meet the gender requirements for the study.
  • Patients who are considered part of a vulnerable population, which means they might need special protection or care.
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Investigated drugs

OP-1250 is an investigational medication being studied for its potential to treat advanced or metastatic breast cancer that is positive for estrogen receptors (ER+) and negative for human epidermal growth factor receptor 2 (HER2-). It is being tested as a monotherapy, meaning it is used alone without combining it with other cancer treatments. The study aims to determine how safe OP-1250 is and how well it works compared to the standard treatments currently available for this type of breast cancer.

What is already known about the treatment

OP-1250 – OP-1250 is an investigational medication administered orally, currently being studied in clinical trials for its effectiveness in treating ER+, HER2- metastatic breast cancer, particularly in patients who have previously undergone endocrine and CDK 4/6 inhibitor therapy. It is in the phase 3 stage of clinical trials, where its safety and efficacy are being compared to standard care treatments. The main therapeutic indication for OP-1250 is advanced or metastatic breast cancer with specific hormone receptor characteristics. At the molecular level, OP-1250 works by targeting and inhibiting estrogen receptors, which are involved in the growth of certain types of breast cancer cells. It is classified pharmacologically as a selective estrogen receptor degrader (SERD).

Investigated diseases

ER+, HER2- metastatic breast cancer – This type of breast cancer is characterized by the presence of estrogen receptors (ER+) and the absence of human epidermal growth factor receptor 2 (HER2-). It typically begins in the breast tissue and can spread to other parts of the body, such as bones, liver, or lungs. The cancer cells grow in response to estrogen, and the disease often progresses slowly. After initial treatments, such as endocrine therapy and CDK 4/6 inhibitors, the cancer may continue to grow or spread, requiring further management. The progression of the disease can vary, with some patients experiencing periods of stability and others facing more rapid advancement.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-505871-63-00Protocol codeOP-1250-301Estimated enrolment892 patientsSponsorOlema Pharmaceuticals Inc.

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