Patients with HER2-positive breast cancer have pretty standard first- and second-line standards of care with Perjeta (pertuzumab) and Kadcyla (T-DM1; ado-Herceptin emtansine) regimens. However, research is still ongoing to improve the treatment for third-line care and beyond, says Kimberly Blackwell, M.D.
The phase 3 NALA study, for example, is exploring the small molecule inhibitor neratinib in combination with capecitabine compared with capecitabine plus Tykerb (lapatinib) in patients with HER2-positive metastatic breast cancer who have received two or more prior HER2-directed regimens (NCT01808573
The safety and tolerability of another small molecule inhibitor, ONT-380, plus capecitabine, Herceptin (trastuzumab), or both, is being investigated in an ongoing phase 1b study (NCT02025192
) in patients with HER2+ metastatic breast cancer who have previously received Herceptin and T-DM1 (for those eligible).
In an interview with CURE
, Blackwell, a medical oncologist at Duke Cancer Institute, discussed the latest therapeutic developments for patients with HER2-positive breast cancer while providing insight on the hurdles that still remain.
Are there any HER2-positive breast cancer advancements you want to highlight?
In the area of HER2-positive breast cancer, it’s not only exciting, but we have a lot of data that help drive decisions for helping our patients facing HER2-positive disease. I reviewed the state of the science in the treatment of patients with HER2-positive breast cancer. We have data now incorporating three novel HER2-targeted agents, including Perjeta, T-DM1 and Tykerb. In each of these, we now have data that drives the orderly fashion: Perjeta in first-line, T-DM1 in second-line, and small molecular inhibitors — Tykerb being one of them — in combination with capecitabine in third-line.
I also stressed the importance of continuing HER2-targeted agents—to not ever let your foot off of the brake when it comes to treating HER2-positive breast cancer.
Finally exciting topics in this area include the novel small molecule inhibitors neratinib and a drug known as ONT-380, which is a pure HER2 small molecule inhibitor. We talked about HER2-directed liposomal chemotherapies, so there are a number of those being studied in clinical trials.
What I am particularly excited about is these super-charged versions of Herceptin. These are antibodies that not only bind to HER2, but also really rev up the immune system. Those are all promising approaches to the treatment of HER2-positive breast cancer.
The FDA recently accepted a new drug application for neratinib. What potential could that agent have if it is approved?
We are all kind of awaiting the data that we don’t yet have on the use of neratinib in the metastatic arena. The strongest data for the activity of neratinib is in the early-stage setting, which is utilizing it after patients have finished one year of adjuvant Herceptin.
With five years of follow-up, data show that it offers a significant improvement in invasive disease-free survival. This is if women complete one year of Herceptin — and they are without evidence of disease — they then take one year of the small molecule pill known as neratinib. If it gets approved, the reality is that it will become a new standard of care. Women who are facing early-stage, HER2-positive breast cancer will complete one year of Herceptin and then go on to receive one year of neratinib, once the regulatory approvals are made available.
The other data that we are awaiting in this space is the study known as APHINITY, and that is a study looking at adding Perjeta in the first year on top of Herceptin. The results of APHINITY and the results of the neratinib study — known as ExteNET — are independent results. If APHINITY is a positive study, I will still be offering patients neratinib after that one year of Herceptin. What do we call that—the year two, HER2 blockade? We are all very excited about it. The data now, with five years of follow-up, really looks like adding a year of neratinib after one year of Herceptin helps prevent disease recurrence. When it becomes available, I will feel obligated to discuss it with my patients.
What remains so impactful about the CLEOPATRA and MARIANNE studies?
CLEOPATRA was important because adding Perjeta really impacted overall survival. However, it didn’t make a significant contribution in terms of toxicity, which we worry about in an incurable metastatic setting.
MARIANNE was an interesting study because it looked at taxane/Herceptin versus T-DM1 or T-DM1 plus Perjeta. What it showed was that T-DM1 plus Perjeta is no better than T-DM1 alone. Additionally, T-DM1 alone has similar efficacy in terms of progression-free survival to taxane/Herceptin.
I don’t think MARIANNE takes away from the CLEOPATRA results. Adding Perjeta on top of the taxane/Herceptin backbone significantly improves survival. It is unfortunate that MARIANNE didn’t yield the positive result for T-DM1 being superior to taxane/Herceptin, but it doesn’t really change my practice. In order to offer patients the best therapy, you need to offer them Perjeta/Herceptin/taxane based on the CLEOPATRA results.
What ongoing studies are exploring the small molecule inhibitors?
There is an ongoing trial with the agent ONT-380, and it’s a clinically savvy, useful study. It takes patients who have received prior Perjeta as well as T-DM1, and then randomizes them to either Herceptin/chemotherapy or ONT-380/capecitabine/Herceptin. As we know, we have familiarity around capecitabine and Tykerb. However, this is really looking at whether we combine a pure HER2-targeted drug — ONT-380 — with Herceptin and capecitabine in the third-line setting. Does that offer us a benefit above what we would give anyway? That’s a priority study.
We also have a study ongoing of capecitabine/neratinib versus capecitabine/Tykerb in a similar patient population, which is accruing. That’s a very clinically useful question. Perjeta is a standard of care for the first-line setting, T-DM1 we are utilizing most in the second-line setting, but what do you do after that? For a lot of these patients, they won’t have seen capecitabine, so those two studies will help define which small molecule we should be using in combination with capecitabine in the third-line setting.
With the progress being made thus far, what challenges remain?
We have made some exciting progress in the field of treating early-stage and metastatic HER2-positive breast cancer. What I would like to see is that we would no longer have to give chemotherapy to achieve the benefits of Herceptin or Herceptin/Perjeta combinations. How do we either alter Herceptin or add immune stimulation to Herceptin, and get the chemotherapy out of the treatment paradigm?
We will get some very good data around immunotherapy in combination with HER2-targeted agents, and there is a lot of good progress that can be made. The progress I would ultimately like to see is to no longer have to give chemotherapy to patients facing HER2-positive breast cancer.