Dr. Adam Brufsky, MD, PhD, Professor of Medicine and Co-Director of the Comprehensive Breast Cancer Program at the UPMC Hillman Cancer Center, talks about a new treatment, called Enhertu, for breast cancer.
Interview conducted by Ivanhoe Broadcast News in 2022.
I wanted to ask you about Enhertu. Could you tell me what subtype of breast cancer this is prescribed for?
BRUFSKY: Enhertu was initially developed for HER2-positive or over-expressing breast cancer, which is about 20 percent of all breast cancer. Women with breast cancers that have low HER2 expression, which corresponds to about another 50 percent of all breast cancer, are now eligible to receive Enhertu. In sum, that’s now 75 to 80 percent of all women with metastatic breast cancer can receive Enhertu.
Is this for women in early-stage breast cancer or more advanced breast cancer?
BRUFSKY: Right now, it’s for advanced breast cancer, that’s breast cancer that has spread outside of the breast and lymph nodes, to lung, liver, bone. Again, that probably represents, at least 40 to 50,000 women in the United States every year, are likely are eligible for Enhertu. If not more.
How is it administered? Is this an oral drug?
BRUFSKY: It’s an intravenous drug. It’s given every three weeks.
Does that require women to come in to get the treatment?
BRUFSKY: Yes. They need to come into clinic every three weeks to get the infusion. Usually, what happens is that we do some sort of evaluation to see if it is working, such CAT scan every 12 to 16 weeks while women are on Enhertu. If their disease is stable or better, they will continue to get Enhertu.
What’s the benefit of having another drug?
BRUFSKY: This is an interesting drug. This is a drug where we take an antibody that binds to HER2 and we put a tiny amount of chemotherapy on it. It’s what’s called an antibody drug conjugate. Some people call it a magic bullet. This is important in that people have been using an antibody against anti-HER2 – antibody against breast cancer that expresses HER2 called Herceptin. These are now biosimilar drugs, but this attaches a little bit of chemotherapy to it and makes it superior to a lot of other things we’ve had before.
Is there anything you would want people to know about having this drug now FDA approved?
BRUFSKY: I think that it really is something that gives us a very active therapy. A therapy that basically at least doubles the amount of time that women can live with their disease without the cancer progressing. It improves their overall survival, even if they’ve had multiple other therapies in the past. I think it’s something really that 75- to 80 percent of all women with metastatic breast cancer can now get. It really is something, I think, that has the potential to really change how we treat breast cancer. Enhertu not only ccan treat breast cancer that has any amount of HER2 expression, but also other cancers with Her2 expression. Examples include lung cancer with HER2 expression, gallbladder cancer with HER2 expression, colon cancer with HER2 expression, and bladder cancer with HER2 expression. Enhertu has been FDA approved for certain indications outside of breast cancer. It’s something that a lot of people now can get.
Would HER2 negative exclude?
BRUFSKY: Her2 expression is determined by the staining of the tumor cells for the her2 protein. Three plus is intense staining in greater than 10% of the cells. Fainter staining in greater than 10% of the cells or intense staining in less than 10% of the cells is one plus or two plus. One plus and two plus were considered “Her2 negative” but now we consider them Her2 low HER2 low. HER2 negative is now HER2 zero where there no staining whatsoever. That’s probably about 20 percent of all breast cancer. It may even be less. We’re developing new tests for HER2 that may make even those zeros have some expression for HER2.
Do you remember the name of the clinical trial that was part of the approval process?
BRUFSKY: There are two separate approvals. The first FDA approval came for HER2 over-expressed, or three plus. Women who had already had onel therapies for HER2 positive metastatic breast cancer were given enhertu or a standard therapy called kadcyla in a trial called Destiny Breast 03, and the enhertu was far better in preventing progression. This led to the FDA approval for this indication. A trial that’s equally if not more important was Destiny Breast 04, and that was woman with HER2 low one plus or two plus (Her2 low) breast cancer. They were treated with the standard therapy or enhertu. These women has been through multiple therapies prior to the randomization. In this trial, Enhertu doubled the length of time they were free of cancer. It also improved the overall survival of these women. This is something where women now live longer, they live better with this drug. There are some side effects. There is nausea, low white count, and about one-third of women may lose her hair with it. The thing that’s a little bit unusual was that some women, around 10%, get lung inflammation, what we call interstitial lung disease. About 7 to 8 percent of the women have to come off Enhertu because of this in the clinical trial. We tell women who are getting enhertu that if they have any unusual breathing symptoms like, worsening cough, worsening shortness of breath, they need to let their doctors know and not wait for their next appointment to tell them. We really need to kind of know about this early.
Is there a limit to the amount of time they can be on this drug?
BRUFSKY: No. Women have been on it for years in the clinical trials. There are several women who have been on it for an extended period longer than that.
Can you refer to this as a maintenance therapy?
BRUFSKY: It’s not really a maintenance therapy. It’s a treatment that can shrink and control the disease. We can use it to women a long time, but it’s not just a maintenance therapy.
END OF INTERVIEW
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