Enhertu Marks First Therapy Approved Across HER2-Positive Solid Tumors

CURE® spoke with an expert about Enhertu for HER2-positive solid tumors and how important this approval is for the patient population.

Treatment with Enhertu (fam-trastuzumab deruxtecan-nxki) “now provides an option for solid tumors,” for patients with HER2-positive solid tumors, an expert said.

The recent accelerated Food and Drug Administration (FDA) approval of Enhertu is important for patients with HER2-positive solid tumors. Of note, Enhertu is the “first drug ever to be approved across solid tumors targeting HER2,” Dr. Sarah Sammons told CURE®.

The FDA’s announcement also stated that eligible patients previously did not have satisfactory alternatives for treatment.

“This is an unprecedented approval because Enhertu is the first drug ever to be approved across solid tumors for diverse HER2-positive cancer types,” Sammons explained. “It is the first tumor agnostic approval for HER2-positive solid tumors defined as having strong immunohistochemistry HER2 staining of three plus, which is really exciting.”

Sammons is a medical oncologist and associate director of the metastatic breast cancer program at Dana-Farber Cancer Institute in Boston.

Enhertu’s approval was based on three clinical trials, including DESTINY-PanTumor02, DESTINY-Lung01 and DESTINY-CRC02. In specific, the DESTINY-PanTumor02 included patients with various cancer types. Sammons stated that these cancer types included biliary tract, bladder, cervical, endometrial and ovarian, and pancreatic tumors.

Sammons explained that oncologists have “a lot of experience” using Enhertu. Notably, it was first approved in 2019 for patients with HER2-positive breast cancer.

“The drug is highly potent and has excellent activity,” she said. “In the DESTINY-PanTumor02 clinical trial, over 50% of patients had actual tumor response or shrinkage of their lesions.”

With this approval of Enhertu, more development and unmet needs have been addressed, Sammons said. She noted that patients with HER2-positive solid tumors did not previously have drugs approved for them across all tumor types.

READ MORE: Expert Overview of HER2-Positive Breast Cancer Treatment

“Classically, we’ve studied HER2 in the context of breast cancer,” Sammons said. “More recently, HER2-positive gastrointestinal cancers such as colon or stomach have received attention.”

She added that HER2-positive solid tumors are rare in some cancer types, such as ovarian and endometrial cancers. Because of rarity, many HER2-positive solid tumor subtypes did not have any FDA-approved treatment options because the population is too small to study.

However, “because this is an approval for any tumor that is HER-2 positive (immunohistochemistry 3+), this now provides an option for solid tumors,” Sammons said.

She emphasized that metastatic tumors should now be tested for the HER protein by immunohistochemistry because testing was not standard before.

“So, this approval now makes that testing important to see if this drug could be an option for patients after standard options.”

Although this approval addresses several unmet needs, some still persist. Sammons explained that HER2 tumors have more of a “propensity to spread to the brain and cause brain metastasis.”

“Brain metastases are always an unmet need in solid tumors,” she said. “Now that we’ve been using Enhertu in breast cancer for quite some time, we know that it works well for HER2-positive breast cancers that have brain metastasis. We don’t know that yet for other HER2-positive solid tumors, but we know Enhertu gets into the brain. So, it would be very important for us to study if Enhertu could be an option for brain metastases from other solid tumors that are HER2-positive, and candidates for Enhertu.”

For respective patients, Sammons encouraged them to ask their doctors about testing to see if they could be eligible for Enhertu.

“For patients who are candidates for the drug that are going on it, I think it’s really important to know that nausea could be a problem,” she said. “Have anti-nausea medications at home and know that if they have a cough or shortness of breath, to let their treatment team know immediately, as inflammation of the lungs is a fairly common but serious side effect of the drug.”

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