For the first time, a targeted medicine can help metastatic breast cancer patients whose tumors express only low levels of HER2.
Clinical trial data published in the New England Journal of Medicine on 5 June 2022 show the drug Enhertu (chemical name: trastuzumab deruxtecan) halved the risk of cancer progression compared to chemotherapy and reduced the risk of death by 36%. The results are expected to change breast cancer treatment, according to experts.
To this point, a patient diagnosed with HER2 breast cancer has been either “positive” or “negative.” About half of metastatic breast cancer patients fall somewhere in between, with tumors that have low but still detectable levels of the protein. Such patients don’t benefit from drugs like Herceptin (chemical name: Trastuzumab), and chemotherapy is the typical treatment for many of them.
Enhertu could become the first HER2-targeting medicine available to these patients. It could also shift how breast cancer is categorized, making it important to know not only whether tumors are HER2-positive, but exactly how much protein they express.
“It’s going to really significantly change our standard of care,” said Nancy Lin, a medical oncologist specializing in breast cancer at the Dana-Farber Cancer Institute. “In general, everyone who has metastatic disease is going to need to know their HER2 status,” and whether it’s defined as “positive, low, or zero.”
Still unknown is exactly what level of HER2 expression is required for Enhertu to work, or how helpful the drug might be for so-called triple-negative patients, who have particularly fast-moving disease.
AstraZeneca and Daiichi, which first claimed study success in February but held off presenting details, have said they intend to submit the results to regulators as soon as possible. In low expressers, the Food and Drug Administration has already granted the drug a Breakthrough Therapy designation, a regulatory tool that is used to speed up reviews.
Currently Enhertu is used as a second-line drug for unresectable metastatic breast cancer and the cost ranges from $200,000 - $430,000 per year, depending on dosage (weight-based) and provider.
Article written by Ginny Fisher, RN, BSN, Managed Care Specialist for Summit Reinsurance Services, Inc. For more information about how this may affect your plan, please contact your Summit ReSources care specialist. The following sources were used as reference material for this article:
BioPharma Dive, 5 June 2022. https://www.biopharmadive.com/news/astrazeneca-daiichi-enhertu-her2-low-breast-cancer-asco/624795/
AMS Predict Rx, accessed 7 June 2022.