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If you or someone you love has ovarian cancer, you may have heard the term “folate receptor alpha” before. This term may sound complex, but the idea is simple. Folate receptor alpha (which you may see abbreviated as FR alpha or FRα) is a protein sometimes found on the surface of cancer cells. Some ovarian cancers have a large amount of this protein. Doctors refer to tumors with a lot of folate receptor alpha protein as being “FR alpha-positive” or having high folate receptor alpha expression. Targeted therapy can treat tumors positive for folate receptor alpha.
In this article, we’ll explain exactly what folate receptor alpha is, why it matters in ovarian cancer, and which tests detect it. We’ll also explain how targeted therapies work and why they may be useful for advanced ovarian cancer. Finally, we’ll share how knowing your folate receptor alpha status can help you understand all the treatment options that may be right for you.
Folate receptor alpha is like a special doorway on certain cells. This protein helps cells take in folic acid — a type of vitamin B that the body needs. The instructions for making folate receptor alpha come from a gene called FOLR1. The FOLR1 gene is like the recipe, and folate receptor alpha protein is the finished product.
Normal tissues tend to have very low levels of folate receptor alpha. However, many epithelial ovarian cancers (a common type of ovarian cancer) make too much of this protein. This is known as overexpression. High folate receptor alpha expression is common in certain gynecologic cancers (cancers that affect women’s reproductive organs). These include:
Studies show that many ovarian cancers carry the folate receptor alpha protein, but levels can vary depending on the specific type of cancer. In one large study of 216 different gynecologic tumors, about 45 percent showed expression of folate receptor alpha. The highest levels were found in high-grade serous ovarian cancers (about 54 percent) and carcinosarcomas (about 60 percent). Other types — such as endometrioid, clear cell, mucinous, and granulosa cell tumors — didn’t show folate receptor alpha expression in this study.
Another recent study found even higher levels of folate receptor alpha in many ovarian cancers. It was found in 72 percent of all primary ovarian cancers and about 82 percent of recurrent (returning) ovarian cancers.
High-grade tumors may also be more likely to express folate receptor alpha compared to low-grade tumors. A tumor’s grade describes how abnormal the cancer cells look under a microscope, compared to healthy ovarian cells, and how quickly they are likely to grow.
Researchers have found that cancers with high folate receptor alpha expression are often more aggressive. Several studies show that tumors with more folate receptor alpha tend to have a higher stage and a higher grade, meaning that the cancer cells look more abnormal and may grow faster.
Some research also shows that people whose tumors have high folate receptor alpha levels may not respond as well to certain treatments. Some research has shown these tumors may be less likely to respond to chemotherapy, including platinum-based chemotherapy drugs — a common ovarian cancer treatment that damages cancer cells to help shrink tumors.
Recent research from several studies shows that folate receptor alpha can help cancer cells grow and survive — especially in high-grade serous ovarian cancer. Other studies show that folate receptor alpha can “turn on” pathways inside cancer cells that help them grow and avoid cell death. These pathways can also contribute to making the cancer harder to treat.
Folate receptor alpha itself doesn’t cause cancer, and it doesn’t mean that treatment won’t work. Instead, knowing details about folate receptor alpha on your cancer cells helps doctors understand how the cancer behaves and whether folate receptor alpha-targeted treatments may be a good option for you.
Many tumor cells have high levels of folate receptor alpha, while most healthy tissues have very little of the protein. This difference means that treatment generally affects the cancer cells more and tends to spare normal cells.
Medicines that attach to folate receptor alpha can deliver treatment straight into the tumor. These therapies are mainly used for advanced or recurrent ovarian cancer. They may also be useful for platinum-resistant ovarian cancer — meaning the cancer no longer responds well to certain chemotherapy drugs. Other targeting treatments are being studied in clinical trials.
Most folate receptor alpha-targeted medicines are a type of antibody-drug conjugate (ADC). An ADC has two parts. The first part is a monoclonal antibody. This is a lab-made protein that acts like a guided key. It’s designed to fit exactly onto the folate receptor alpha “lock” on the cancer cell. The second part is a cytotoxic drug — one that can damage or kill cancer cells.
When the antibody attaches to folate receptor alpha, the medicine is pulled inside the cancer cell. Once inside, the drug is released and begins to destroy the cancer cell from within. This helps focus treatment on cancer cells while lowering the impact on healthy tissue.
As of December 2025, only one drug that targets folate receptor alpha is approved by the U.S. Food and Drug Administration (FDA) to treat ovarian cancer. It’s called mirvetuximab soravtansine-gynx (Elahere). Mirvetuximab soravtansine-gynx received accelerated approval in 2022 after positive results were published from clinical trials. The drug was granted full approval in 2024 after its benefits were confirmed in larger clinical studies.
It may be used after someone has already tried one to three previous treatments (one being platinum based).
Mirvetuximab soravtansine-gynx is approved for adults with folate receptor alpha-positive platinum-resistant ovarian cancer, fallopian tube cancer, or primary peritoneal cancer. It’s mainly used for advanced epithelial ovarian cancer.
Researchers are also studying this targeted treatment in other cancers, including endometrial cancers and a small number of breast cancers. However, these uses are still being tested in oncology clinical trials.
Folate receptor alpha is a biomarker. Biomarkers indicate features of cancer cells that can help guide treatment decisions. Knowing your folate receptor alpha level can help your healthcare team decide whether targeted therapy may be a good option for you.
Doctors test for folate receptor alpha and other biomarkers by looking closely at your tumor cells. During surgery, a doctor removes a tiny piece of the tumor so it can be studied under a microscope. This procedure is called a biopsy.
The main biomarker test is called immunohistochemistry. This lab test uses special stains or dyes to show how much folate receptor alpha is on the cancer cells. The pathologist (a doctor who studies cells and tissues under a microscope) looks at how “bright” the stain is and how many cells have it. These immunohistochemical results help determine if your tumor has low, medium, or high folate receptor alpha expression.
If you have ovarian cancer, your doctor can recommend whether folate receptor alpha testing is right for you. Biomarker testing can show whether a targeted treatment or a clinical trial may be a good option. Even if your tumor isn’t positive for folate receptor alpha, you may qualify for other targeted therapies based on the unique features of your cancer. Your care team can explain your treatment options and help you decide on the regimen that fits your needs.
On MyOvarianCancerTeam, people share their experiences with ovarian cancer, get advice, and find support from others who understand.
Has your ovarian cancer been tested for folate receptor alpha or other biomarkers? Let others know in the comments below.
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