Mothaffar F. Rimawi, MD
Precision medicine has become essential in delivering optimal and individualized care for patients with HER2-positive breast cancer.
Specifically, this type of approach was investigated in the NSABP B-47 trial, which aimed to determine the value of trastuzumab (Herceptin) plus standard adjuvant chemotherapy in patients with low levels of HER2 protein. This trial’s findings showed no significant efficacy, demonstrating the importance of targeting treatments for patients based on their genetic mutations, explained Mothaffar Fahed Rimawi, MD, in an interview during the 2017 San Antonio Breast Cancer Symposium (SABCS).
In the NSABP B-47 study, which was presented at the meeting, results showed that the 5-year invasive disease-free survival rate was 89.6% among the 1640 patients who received trastuzumab and 89.2% among the 1630 patients who did not (95% CI, 0.77-1.26; P
= .9). Investigators said the findings were no different whether patients were subdivided by HER2 immunohistochemistry level, extent of lymph node involvement, or hormone receptor status.
Rimawi, associate professor, Baylor College of Medicine, medical director and director of clinical research at Baylor's Lester and Sue Smith Breast Center and the Smith Clinic/ Ben Taub Hospital, and co-leader of the breast program at Baylor's Dan L. Duncan Cancer Center, discussed the significance of precision medicine in HER2-positive breast cancer, as well as the possible role of immunotherapy for this specific population.
OncLive: What is the importance of precision medicine in HER2-positive breast cancer?
[At SABCS] I discussed the research that is shedding light on HER2-positive breast cancer, including mechanisms of resistance, sensitivity, and the efforts to tailor treatments to the individual patient.
I moderated 2 sessions where a panel of experts received challenging cases from the audience and provided treatment recommendations based on the latest available evidence. These contributions show the strength of this [medical] meeting, where science and clinical medicine come together to push forward patient care by utilizing the best possible care models and the best science.
From your perspective, what was the most exciting advancement in the field of breast cancer in 2017?
It is hard to pinpoint 1 thing. In my opinion, the most impressive thing about breast cancer is the incremental improvement in patient outcomes that have been ongoing year after year. Although a small increment does not sound exciting, when you add those up with different treatment modalities for years, we are seeing the mortality from breast cancer going down and women are living longer, healthier lives.
You see 3 different levels of improvements or achievements. One involves very robust meta-analyses where clinical trials from all over the world pool their data together. When that happens, there are 10,000 women treated with similar treatments and followed for 10 to 20 years. Powerful data have shown us that giving patients the treatments that we know work, such as chemotherapy for higher-risk patients and endocrine therapy for estrogen receptor (ER)-positive patients, are continuing to make a difference in the lives of women. We know that giving the chemotherapy on a more dose-dense schedule has robustly demonstrated to improve outcomes for these patients. The power of collective knowledge is one area of achievement.
The other area is the strength that we are seeing in precision medicine. Multiple trials have reported showing that we need to target the right treatment to the right person. The NSABP B-47 trial that was reported at SABCS sought to determine whether anti-HER2 therapy with trastuzumab would be beneficial to women who have lower levels of HER2 expression.
This trial would be considered negative under clinical standards but, the question was, “If they have some level of HER2 expression, would they benefit from anti-HER2 treatment?” This trial showed conclusively that it is not the case. You need to target anti-HER2 treatment to those who are HER2-positive and extending a treatment that works well for 1 group of patients to other patients may not work. That is a win for precision medicine and for the idea that it is important to tailor treatment to the patients.