Table of Contents
- What is OP-1250?
- How does OP-1250 work?
- What types of breast cancer does OP-1250 treat?
- Current Clinical Trials
- Combination Therapies
- Safety and Side Effects
- Potential Benefits
What is OP-1250?
OP-1250 is a new medication being developed for the treatment of advanced or metastatic breast cancer. It is classified as a small molecule and a Complete Estrogen Receptor ANtagonist (CERAN)[1][2]. A small molecule is a type of drug that can easily enter cells due to its size, while a CERAN is a medication that blocks the effects of estrogen on cancer cells.
How does OP-1250 work?
OP-1250 works by targeting and blocking estrogen receptors in breast cancer cells. Estrogen can promote the growth of certain types of breast cancer, so by blocking these receptors, OP-1250 aims to slow down or stop the growth of cancer cells[1].
What types of breast cancer does OP-1250 treat?
OP-1250 is being developed specifically for patients with:
- Hormone Receptor-positive (HR+) breast cancer: This means the cancer cells have receptors for either estrogen or progesterone, which can promote cancer growth.
- HER2-negative breast cancer: This means the cancer cells do not have high levels of a protein called HER2, which can promote cancer growth.
- Advanced or metastatic breast cancer: This refers to cancer that has spread beyond the breast to other parts of the body or is at an advanced stage[1][2].
Current Clinical Trials
OP-1250 is currently being studied in clinical trials to determine its safety and effectiveness. There are two main trials in progress:
- Phase 1 and 2 Monotherapy Study: This trial is testing OP-1250 as a single treatment (monotherapy) in patients with advanced or metastatic HR+, HER2-negative breast cancer. The study aims to determine the best dose and evaluate the safety and effectiveness of OP-1250[2].
- Phase 1b Combination Study: This trial is testing OP-1250 in combination with other cancer drugs (ribociclib, alpelisib, or everolimus) in patients with advanced or metastatic ER+, HER2-negative breast cancer[1].
Combination Therapies
Researchers are exploring how OP-1250 works in combination with other cancer medications. The combinations being studied include:
- OP-1250 with Ribociclib (KISQALI®): Ribociclib is a CDK4/6 inhibitor, which helps stop cancer cells from dividing.
- OP-1250 with Alpelisib (PIQRAY®): Alpelisib is a PI3K inhibitor, which blocks a protein involved in cancer cell growth.
- OP-1250 with Everolimus: Everolimus is an mTOR inhibitor, which also helps stop cancer cell growth[1].
Safety and Side Effects
As OP-1250 is still in clinical trials, its full safety profile is not yet known. The ongoing studies are carefully monitoring for any side effects, which are referred to as treatment emergent adverse events (TEAEs) and serious adverse events (SAEs). These are being assessed using standardized criteria called the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE)[1][2].
Potential Benefits
While it’s important to note that OP-1250 is still in the testing phase, researchers are hopeful about its potential benefits. They are looking at several measures to determine if OP-1250 is effective:
- Objective Response Rate (ORR): This measures how many patients’ tumors shrink or disappear after treatment.
- Clinical Benefit Rate (CBR): This looks at how many patients’ cancers either shrink or remain stable for at least 24 weeks.
- Duration of Response (DoR): This measures how long the cancer remains controlled after it starts responding to treatment[1].
These clinical trials will help determine if OP-1250 is safe and effective for treating advanced HR+, HER2-negative breast cancer, either alone or in combination with other treatments. If successful, OP-1250 could provide a new treatment option for patients with this type of breast cancer.


