Mirvetuximab Soravtansine for Ovarian Cancer

Medically Reviewed by Laura J. Martin, MD on August 03, 2022
5 min read

Many people with epithelial ovarian cancer (EOC) respond to treatment at first. But cancer comes back, or recurs, in up to 80% of those who get better. Over time, a common treatment for advanced ovarian cancer may not help anymore. That’s called platinum-resistant ovarian cancer.

Scientists continue to study new treatments for drug-resistant ovarian cancer. One targeted therapy shows a lot of promise. Get the facts on mirvetuximab soravtansine.

It’s in a class of drugs called antibody-drug conjugates, or ADCs. These are targeted drugs sometimes used to treat cancer. ADCs are made in a way that chemically joins a cancer-fighting drug with a monoclonal antibody.

Scientists make monoclonal antibodies (mABs) in a lab. But they work a lot like the kind your body makes to kill disease-causing germs. Like regular antibodies, mABs can narrow in on certain kinds of cells. That includes some that play a role in cancer.

Mirvetuximab soravtansine (MIRV) uses a mAB that finds and binds to folate receptor-alpha (FR-alpha). FR-alpha helps get folate, a B vitamin, into cells. There’s evidence that aggressive ovarian cancer cells have a lot more of these receptors than normal tissue.

Unlike chemotherapy, MIRV doesn’t affect every cell in your body. It delivers treatment directly into cancer cells. This lessens the chances of damage to nearby healthy tissue. And the cancer-fighting part of the drug stays inactive until it binds to the right receptor.

Think of receptors like little signals that identify a cell. Compared to healthy cells, ovarian cancer cells have more FR-alpha flags on the surface. That’s how MIRV locates cancer cells in your body.

Here’s a breakdown of how it works:

MIRV floats around in your bloodstream. Then the FR-alpha antibody finds a cancer cell. It attaches to it. Special properties then release a drug molecule called DM4 inside the cancer cell. DM4 breaks up the formation of microtubules. Those are a vital part of a cell’s structure.

As a result of this process, MIRV can make it harder for ovarian cancer cells to grow and stay alive.

MIRV is only approved for people who take part in clinical trials.

With that said, scientists are using it to treat platinum-resistant EOC. That generally means cancer that comes back 6 months after you’ve tried platinum-based chemotherapy or other kinds of cancer treatments.

Researchers have found that MIRV works best against tumors that express a high level of FR-alpha. Doctors can test a piece of a tumor to see if it’s FR-alpha positive.

There’s ongoing research to see if MIRV can treat other kinds of cancer. That includes primary peritoneal and fallopian tube cancers.

This is an ongoing area of research.

It’s not clear if or how long MIRV will prevent disease progression in the long run. But early studies show MIRV may keep some women with platinum-resistant EOC cancer-free for longer periods of time.

Here’s what some studies have found:

Forward I study. Researchers included 366 people with platinum-resistant EOC. They gave MIRV to 243 members of the group. The other 109 received chemotherapy. The results showed that MIRV didn’t slow cancer better than chemotherapy in everyone with EOC. But it did benefit those with high FR-alpha expression in their tumors.

SORAYA study. Researchers gave MIRV to 106 people with recurrent platinum-resistant EOC. Each person had up to three prior treatments, including chemotherapy or PARP inhibitors. They’d all received bevacizumab (Avastin). That’s a cancer drug that stops tumors from growing more blood vessels.

After an 8-month follow-up, results showed an overall response rate (ORR) of 32.4%. The ORR refers to the percentage of people in the study whose cancer got smaller or totally went away. And in five people, there were no signs of cancer after treatment with MIRV.

Compared to typical results with chemotherapy, people with platinum-resistant EOC tend to show an ORR of 15% or less. It can be as low as the single digits for some. And it’s rare to see a complete response.

And so far, the middle range for a duration of response – how long the drug slows cancer growth – is about 6.9 months. But treatment is still working for some people in the study. Researchers will keep an eye on them going forward.

MIRV is given as an infusion. That’s when you get medicine through a vein in your arm.

In the SORAYA and Forward I studies, each participant got a weight-based dose on day 1 of a 21-day cycle. Treatment continued every 3 weeks until either the cancer grew or they couldn’t tolerate the side effects.

Ongoing research will tell us more about the recommended dose and schedule for big groups of people.

Studies show people handle MIRV pretty well. It may be easier to take than chemotherapy. But like other drugs, it may cause some unwanted symptoms. According to early research, these side effects tended to be mild, treatable, and reversible.

The most common side effects included:

  • Feeling sick to your stomach (nausea)
  • Diarrhea
  • Blurry vision
  • Fatigue
  • Eye problems of the cornea (keratopathy)
  • Dry eye

Less often, people had:

  • Weakness, numbness, or pins and needles (peripheral neuropathy)
  • Throwing up
  • Lack of hunger
  • Less clear eyesight

You may also have a reaction to where the needle goes into your body. That might include:

  • Pain or soreness
  • Swelling
  • Redness
  • Itchiness or rash

Eye side effects occur more often with ADCs than traditional chemotherapy. But there are ways to help your eyes feel better.

Ask your doctor to go over the pros and cons of any medication you take. Tell them about anything that makes you feel bad. Your cancer care team can help ease your symptoms. That’s called palliative care. You can ask your doctor about it at any point during your treatment.

Scientists continue to study how well MIRV works for people with platinum-resistant ovarian cancer, especially when compared to chemotherapy.

In the future, some experts think MIRV may be the go-to treatment for people with FR-alpha positive ovarian cancer. And it’s on the fast track for FDA approval. But it’s not something everyone can get right now. Though you may be able to try the drug as part of a research study.

Ask your doctor to help you decide if a clinical trial is right for you. Or find more information at ClinicalTrials.gov. You can also use the “Find NCI-Supported Clinical Trials” tool on the website of the National Cancer Institute.