Ovarian cancer begins in the ovaries, the female reproductive organs that produce eggs and estrogen. According to the American Cancer Society (ACS), it’s the fifth-leading cause of cancer death in women. But it can impact anyone with ovaries.

Ovarian cancer is primarily treated with surgery and chemotherapy. But, if you have advanced ovarian cancer, your doctors may recommend an add-on treatment called immunotherapy.

In this article, you’ll learn more about immunotherapy for ovarian cancer, whether it’s effective, and how it may be used as part of your cancer treatment plan.

Your immune system protects you from viruses, bacteria, and other infections.

In an ideal world, your immune system would be able to protect you from cancer cells, too. But unlike a virus, which your immune system recognizes as a foreign invader, cancer cells are still a part of you. Because of this, the immune system doesn’t effectively recognize and respond to cancer.

Immunotherapy is a form of cancer treatment that helps your immune system learn how to identify and respond to cancer cells.

There are several types of immunotherapy, including:

  • Immune checkpoint inhibitors: These are drugs that help the immune system better detect cancer cells.
  • Monoclonal antibodies: These are manufactured antibodies that can target specific aspects of cancer cells.
  • Chimeric antigen receptor T-cell therapy: CAR T-cell therapy trains certain immune cells, called T cells, to find and destroy cancer cells.
  • Cytokines: These are proteins that can stimulate the immune system.
  • Immunomodulators: These are drugs that help boost the immune system.
  • Cancer vaccines: These are vaccines that trigger the immune system to respond to cancer.
  • Oncolytic viruses: These are modified viruses that are designed to infect and kill cancer cells.

Immunotherapy isn’t a common treatment for ovarian cancer. In fact, a 2020 review of studies found that, when it comes to treating ovarian cancer, most types of immunotherapy are still being tested in clinical trials.

If you have advanced ovarian cancer, immunotherapy could be an option for you. But your doctor may have to help you enroll in a clinical trial.

Additionally, according to the ACS, the immune checkpoint inhibitor pembrolizumab (Keytruda) may be used for ovarian cancer in specific situations. Examples of such situations include:

  • when the cancer is advanced
  • when the cancer has certain levels or types of genetic changes
  • when the cancer has started growing again after treatment with other cancer drugs like chemotherapy or targeted therapy

Pembrolizumab is given as an intravenous (IV) infusion. According to the drug label, you may receive it every 3 weeks or every 6 weeks.

Immune checkpoints are a normal component of your immune system. Their function is to help prevent your immune system from responding too strongly, in a way that would damage healthy cells.

Certain immune cells, known as T cells, play an important role in the immune system. T cells have an immune checkpoint protein on their surface. When this protein binds to a corresponding protein on certain cancer cells, it sends a signal to “turn off” the T cell.

When T cells are turned off, they can no longer attack cancer cells.

Immune checkpoint inhibitors (ICIs) are drugs that work by interrupting this process. They prevent the signal that switches the T cells off, which means the T cell is free to attack the cancer cell.

Several clinical trials in recent years have explored the use of ICIs for ovarian cancer. The results of been promising, but mixed. ICIs are rarely used as the sole treatment for ovarian cancer.

The ICIs currently used in the treatment of different cancers include:

Immunotherapy with immune checkpoint inhibitors (ICIs) is sometimes used for advanced ovarian cancer. But these drugs are rarely used alone.

A 2021 review analyzed 15 clinical trials of ICIs for ovarian cancer. When these drugs were used alone, the overall response rate was only 9%. A higher response rate (36%) was seen when they were combined with chemotherapy.

When caught early, before it spreads, the outlook for ovarian cancer is actually quite good. But the outlook for advanced ovarian cancer is not as favorable, with a 5-year relative survival rate of 30.8%.

According to the SEER program of the National Cancer Institute, around 80% of people with ovarian cancer aren’t diagnosed until their cancer has already spread beyond the ovaries.

Combination therapy

Since treatment with ICIs alone doesn’t appear to be effective, clinical trials have begun to focus on using ICIs in combination with chemotherapy and other types of cancer drugs. Some of the results are promising.

For example, a 2020 clinical trial involving 40 people with recurrent ovarian cancer looked at treatment with pembrolizumab in combination with a targeted therapy drug and a chemotherapy drug.

It found that 95% of participants that received this combination therapy benefited from it in some way. Around 25% of those participants had a treatment response that lasted longer than 12 months.

Using different combinations of ICIs may also be helpful. A 2020 clinical trial found that using nivolumab (Opdivo) plus ipilimumab (Yervoy) led to a better treatment response rate. It also slightly increased progression-free survival rates.

Like any type of cancer treatment, immunotherapy for ovarian cancer can come with some side effects. These may include:

More serious side effects are rare. These can include a type of allergic reaction, called an infusion reaction, while receiving your treatment infusion. Autoimmune reactions, when your immune system mistakenly attacks healthy cells, can also occur.

Before you start on any type of cancer treatment, your care team will inform you of the types of side effects that you may encounter. Be sure to reach out to them if you begin to experience any concerning side effects from your treatment.

Immunotherapy is still an up-and-coming treatment for ovarian cancer. Because of this, doctors and scientists are working hard to find newer, more effective ways to use different types of immunotherapy.

This is accomplished through clinical trials. If you have ovarian cancer and are interested in immunotherapy, talk with your care team to see if there are any trials that you’d qualify for.

You can look through the list of ovarian cancer clinical trials supported by the National Cancer Institute, many of which involve immunotherapy. Also, ClinicalTrials.gov is a searchable database of privately and publicly funded clinical trials worldwide.

As we mentioned earlier, there are other more common treatments for ovarian cancer. These include:

  • Surgery: This involves a surgical procedure to remove the cancer from the body.
  • Chemotherapy: Chemotherapy uses drugs that can kill cancer cells or slow down their growth.
  • Targeted therapy: This treatment uses drugs that target specific aspects of cancer cells.

Which type of treatment is recommended for your ovarian cancer depends on many factors. Some of these include:

  • the specific type of ovarian cancer that you have
  • the extent (stage) of the cancer
  • the characteristics of the cancer, such as biomarkers and genetic changes
  • which other types of treatments have been used, if any
  • your age and overall health
  • your personal preference

Immunotherapy is a type of cancer treatment that aims to help your immune system better respond to cancer. It’s not yet a common treatment for ovarian cancer.

However, in some cases your doctor may suggest immunotherapy as a part of your treatment. This will likely be done as part of a clinical trial, either alone or in combination with other cancer drugs.

If you’re interested in immunotherapy for your ovarian cancer, talk with your care team. You may be eligible for a clinical trial that’s currently enrolling participants.