Evolving options in the third-line setting and after
For third-line therapy and beyond, oncologists have an array of newer agents to choose from alongside longer-standing options — which include trastuzumab plus lapatinib, trastuzumab or lapatinib plus capecitabine, as well as T-DM1, if not given as second-line therapy.
According to Dr. McCann, the antibody-drug conjugate trastuzumab deruxtecan has been a particularly exciting addition to third-line treatment. In the phase 2 DESTINY-01 trial, more than 60% of a heavily pretreated population showed an objective response to trastuzumab deruxtecan, with a median response duration of almost 15 months and a median progression-free survival of 16.4 months. Longer-term follow-up results, presented in December at the 2020 San Antonio Breast Cancer Symposium, revealed progression-free survival of 19.4 months and preliminary median overall survival of 24.6 months.
Neratinib, the second TKI to bridge the blood-brain barrier in HER2-positive disease, was also approved for third-line use; however, Sayeh Lavasani, MD, MS, said she is more likely to consider this agent later in the sequence, potentially in the fourth-line setting and beyond, given the more robust outcomes observed in the HER2CLIMB tucatinib trial.
“Neratinib improved progression-free survival and time to intervention for CNS metastasis but, unlike tucatinib, did not demonstrate an overall survival benefit,” remarked Dr. Lavasani, a medical oncologist at City of Hope, a comprehensive cancer center in Los Angeles County.
More specifically, the phase 3 NALA trial, which randomly assigned patients to receive neratinib plus capecitabine or lapatinib plus capecitabine, reported progression-free survival of 8.8 months in the neratinib group compared with 6.6 months in the control arm but no significant gains in overall survival (hazard ratio, 0.88; P = .2098).
The fourth recently approved drug, margetuximab, has not yet made a significant mark on sequencing decisions for Dr. McCann.
“Margetuximab could have been a potential game changer, but clinical trial results were underwhelming,” she said.
In the phase 3 randomized clinical SOPHIA trial, margetuximab plus chemotherapy prolonged median progression-free survival by just over 1 month compared with trastuzumab plus chemotherapy. Preliminary overall survival data showed a slight, but not significant, benefit in the margetuximab group (21.6 vs 19.8 months).
For Dr. Lavasani, the presence of brain metastases is the most important consideration when weighing sequencing options. “For some of my patients with HER2-positive MBC, it’s ultimately disease progression in the brain that takes their life,” she said.
Aside from CNS metastases, specific sequencing choices may vary on the basis of drug-related tolerance as well as patient preferences. “It is critical to get a patient’s input in treatment selection,” Dr. Nanda remarked. “Given the number of effective treatments for HER2-positive MBC and the lack of data to guide how to sequence these regimens, it is important to ask patients what their preferences are.”
Dr. McCann agreed, noting that “a patient with HER2-positive MBC typically has a life expectancy measured in years, which is also why sequencing should be influenced by quality of life considerations.”
Convenience, side-effect profile, and financial toxicity should factor into clinical decision-making, according to Dr. Nanda. Some patients may, for instance, prefer a combination of tucatinib, capecitabine, and trastuzumab over trastuzumab deruxtecan to avoid hair loss and the risk for interstitial lung disease, which has been reported in more than 13% of patients, whereas others may prefer trastuzumab deruxtecan to avoid the possibility of diarrhea.
Taxanes come with a high risk for infusion reactions — which occur in about 30% of patients — and can cause neuropathy as well as hair loss and severe gastrointestinal side effects. In first-line care, Dr. McCann typically stops the taxane at some point for toxicity reasons and continues with trastuzumab plus pertuzumab until disease progression.
Even with an array of new options for treating metastatic HER2-positive disease, ultimately drug resistance does occur, Dr. Lavasani cautioned. Several ongoing trials are exploring new combinations of existing drugs to see whether those variations move the needle on survival outcomes. The HER2CLIMB-04 trial, for instance, is pairing tucatinib with trastuzumab deruxtecan, whereas HER2CLIMB-02 is pairing tucatinib with T-DM1.
But given progress in drug development in just the past few years, Lisa A. Carey, MD, deputy director of Clinical Sciences at the University of North Carolina Lineberger Comprehensive Cancer Center in Chapel Hill, sees a promising future for treating metastatic HER2-positive disease. “There is so much going on in the HER2-positive MBC therapeutics space that almost every 6 months, oncologists have to regroup and reevaluate treatment and sequencing, which is a great position to be in,” Dr. Carey noted.
A version of this article first appeared on Medscape.com .