New Pan-Tumor Approval For Enhertu: HER2 Testing Needed For Many More Patients
- A major new approval for Enhertu, a drug targeting the HER2 protein, creates a potential treatment option for many more patients with recurrent, metastatic solid tumors
- Enhertu delivers a dose of toxic chemotherapy while attempting to spare healthy cells and create fewer side effects
- Immunohistochemistry (IHC) testing detects HER2, a protein that promotes rapid cancer growth, aiding in the assessment of aggressive cancers.
- IHC testing for HER2 is not yet routine for many solid tumors
- A positive HER2 status, indicated by IHC scores of 3+, responds well to Enhertu, a drug effective across various advanced cancer types.
“What is going to be critical to making sure that every eligible patient has the opportunity to be identified through IHC testing in the journey of metastatic disease, says Ashley Gaines, who leads the US breast cancer and HER2 teams at the drug company, AstraZeneca.
Read MoreHaving the information is valuable at any point during treatment because it helps doctors make informed decisions about which therapies are likely to work best for each patient, she says.
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A New Type Of Cancer Treatment
If the IHC test returns a score of 3+ it is likely to respond well to Enhertu.
With the new approval, Enhertu is what’s known as a tumor-agnostic treatment which means it has shown benefit for many types of cancers that express high amounts of HER2. It is sometimes referred to as a pan-tumor treatment from the Greek word for all,“pan”.
As an ADC drug, or antibody-drug conjugate, Enhertu is a type of medication that acts like a smart bomb that combines an antibody (a protein that targets specific markers on cancer cells) with a powerful cancer-fighting drug.
The antibody part of the ADC finds the cancer cells and delivers the drug part directly to them, which helps kill the cancer cells while sparing healthy ones. In the case of Enhertu, the target is HER2.
“If you look today at five-year survival rates across many of these different tumor types, unfortunately they’re abysmal with a third or fewer patients surviving five years or more,”Gaines says.
“And what that means is that there is just an unmet need for new efficacious treatments beyond that initial treatment, which may be the standard of care for a given tumor type,” she adds.
Studies that led to the tumor agnostic US Food and Drug Administration (FDA) approval of Enhertu show that it is effective for treating several HER2+ (IHC 3+) cancers. It is particularly effective for treating gynecological cancers such as cervical, ovarian, and endometrial.
Related: How to Treat Metastatic Breast Cancer
Expanding Awareness and Accessibility of HER2 Testing
Many patients with solid tumors are not tested for HER2, Gaines notes. They may not even understand what it means to be HER2 positive.
Gaines stresses the need for greater awareness and accessibility of IHC testing to identify candidates for HER2-targeted therapies.
“IHC testing is the key to identifying patients who could be eligible for treatment within HER2. And although IHC testing is relatively simple to do, it is readily available, it is commonplace in cancers like breast cancer. It is not yet routine in many of these other types of solid tumors,” says Gaines.
By identifying HER2 positive patients, Enhertu can be effectively employed, offering hope through targeted treatment, Gaines says.
As IHC testing becomes more integrated into oncological practice, it holds the promise of transforming cancer care by enabling more precise and effective treatments.
“The key to identifying these patients is going to be that IHC testing and really embedding that as habit within the community at large,” she says. “This approach not only enhances the effectiveness of current treatments but also opens doors to new therapeutic possibilities.”
Related: What The Amazing New Findings About The Drug Enhertu Mean For You & What To Ask Your Doctor
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