Mirvetuximab Soravtansine (Elahere) Report Card: Three Years Of Real-World Data

Three years after its November 2022 approval, mirvetuximab soravtansine (Elahere) has become a standard treatment for people with advanced FRα-positive, platinum-resistant ovarian, fallopian tube, and primary peritoneal cancer who have received one to three prior lines of therapy.

Recently, Dr. Premal Thaker, a gynecologic oncologist/surgeon at Siteman Cancer Center in St. Louis, sat down with SurvivorNet Connect to talk about what real-world data can tell us about mirvetuximab, its side effects, and what’s next for FRα-targeting antibody-drug conjugates (ADCs). 

How Mirvetuximab Changed Research

Mirvetuximab is a first-in-class ADC targeting folate receptor-alpha (FRα). It’s approved for patients with advanced, platinum-resistant ovarian cancer who have 75% or more FRα-positive tumor cells. Around 90% of people with ovarian cancer express some amount of FRα, and around 35% have enough FRα-positive cells to be candidates for mirvetuximab. 

In clinical trials, mirvetuximab not only provided a progression-free survival benefit, but also overall survival. “It was the first time we saw a progression-free survival benefit compared to traditional chemotherapy, and then we got confirmation with overall survival benefit,” Dr. Thaker explains. “This was the first time where it also changed what the FDA thought we could achieve. Before we’d always relied on progression-free survival since we never got an overall survival benefit. Mirvetuximab really opened up the way we can make better medications.” 

Since mirvetuximab’s approval, NCCN Guidelines have been updated to recommend the drug as a Category 1, preferred medication for platinum-resistent, epithelial ovarian, fallopian tube, or primary peritoneal cancer with high expression of FRα.  

Report Card On Accessibility

Immediately after mirvetuximab’s approval, there were accessibility challenges with testing for FRα expression. FRα expression is measured with an IHC assay, which has become a standard part of the initial testing done at diagnosis.

“I don’t think they realized how many people would want to test their patients,” Dr. Thaker explains. “Even though they had commercial vendors that they had partnered with, there were some shortages. Now it’s part of all the commercial testing sites. It comes standard.”

There may be some patients who were not tested at their diagnosis, so Dr. Thaker stresses the importance of confirming FRα expression was measured and completing IHC assay if not after a cancer recurrence.

Mirvetuximab & Ocular Toxicity

Some ADCs, including mirvetuximab, carry potentially severe side effects affecting the eyes.  These include: 

• Visual impairment/blurred vision
• Keratopathy
• Dry eye
• Photophobia 
• Eye pain
• Uveitis 

A small real-world study of mirvetuximab published in Gynecologic Oncology Reports found that 64% of the 25 patients studied experienced ocular toxicity, with 16% experiencing a grade 3 ocular toxicity. Eye problems were more common in patients who had received more lines of therapy, but they were not more severe for that group. 

Another real-world study shared at the 2024 American Academy of Ophthalmology conference showed that more than 55% of patients treated with mirvetuximab had vision problems due to damage to the cornea. In the trials that led to mirvetuximab’s approval, ocular reactions occurred in 59% patients, with 11% experiencing Grade 3 reactions. Of those who had eye problems, 53% had a complete resolution and 38% saw improvement. Only 1% of patients discontinued mirvetuximab due to vision changes. 

Understanding how to manage the ocular toxicity has been a learning curve for oncologists. “We all had to learn how to become an ophthalmologist. We’re oncologists, and we don’t really hold an otoscope or slid eye exam equipment in our offices,” Dr. Thaker notes. 

When prescribing mirvetuximab, patient education about the ocular toxicity associated with the drug is essential. Steroid eyedrops and lubricating eyedrops are needed to prevent the side effects, as well as continued follow-up.

“With these mitigation strategies, patients can do very well, but it is work on the patient’s part to remember to take all these eyedrops and go to the ophthalmologist,” Dr. Thaker adds. 

Mirvetuximab can also be a challenge for patients in more rural settings, since they may not have easy access to an ophthalmologist and may need to see an optometrist instead. 

Mirvetuximab’s Other Side Effects

Ocular toxicity is not the only serious side effect of mirvetuximab. It also carries a risk of neuropathy and interstitial lung disease (ILD), both of which are well-known adverse events associated with ADCs. 

Thirty-six percent developed neuropathy, with 3% experiencing grade 3 neuropathy. The neuropathy can be severe for some patients. “Some of it is not just sensory,” Dr. Thaker says. “It can be muscular, and if it is muscular then it makes it harder for patients to walk.” That can lead to treatment discontinuation. 

Around 10% of patients treated with mirvetuximab developed ILD. Of those, 1% had Grade 3 ILD and one patient developed Grade 4 ILD. ILD and pneumonitis lead to discontinuation of mirvetuximab in 3% of patients. 

What’s Next?

Clinical trials are currently underway to test a new FRα-targeting ADC called LY4170156. Initial results from the first-in-human phase 1 trial were presented at ASCO 2025. Dr. Thaker thinks the early results are promising. 

“I do think the new compound has a lot of strengths that mirvetuximab currently does not have, which is you don’t need to have FRα positivity in order to have a benefit. They had patients with low expression (less than 50%). They had patients with even no expression who saw a benefit. I think it’s tremendous,” said Dr. Thaker. 

The side effects with this new drug also appear more manageable. There have been no cases of ocular toxicity or ILD in the reported data for LY4170156. 

“I have to say, it is very exciting,” said Dr. Thaker. “Now we have ADCs, we have immunotherapy, we have exciting clinical trials […] Things are moving forward and have better outcomes for our patients.”