<b>Background:</b> Comparative real-world outcomes for patients with HER2-positive (HER2+) breast cancer receiving adjuvant trastuzumab outside of clinical trials are lacking.
<b>Introduction</b>: CT-P6 (trastuzumab-pkrb, Herzuma) is a trastuzumab biosimilar approved for use in HER2 positive breast cancer and HER2 positive gastric cancer.
<b>Methods:</b> Static (two dimensional, 2D) and three-dimensional dynamic (3DD) cell culture studies were conducted using JIMT-1 cells, a HER2+ BC cell line refractory to HER2 therapies.
<b>Patients and methods:</b> HER2-positive BC patients receiving NAT ± trastuzumab were retrospectively included between January 2013 and December 2016.
<b>Purpose:</b> Radiotherapy for patients with non-metastatic human epidermal growth factor receptor 2 (HER2) positive breast cancer is commonly administered concurrently with adjuvant trastuzumab.
<i>PIK3CA</i> mutation is considered to be a possible cause for resistance to neoadjuvant chemotherapy (NAC) in human epidermal growth factor receptor 2 (HER2)-positive breast cancer.
<sup>18</sup>F-FDG-PET/CT revealed distant metastases in 14% (95% CI: 9-20%) of patients with stage IIB ER+/HER2- and HER2+ breast cancer, which is similar to upstaging rates previously seen in patients with stage IIB triple-negative breast cancer (15%, 95% CI: 9-24%).
HER2-positive breast cancer cells resistant to trastuzumab and lapatinib lose reliance upon HER2 and are sensitive to the multitargeted kinase inhibitor sorafenib.
HER2 overexpression in a basal, rather than in a luminal molecular background, results in a basal/HER2+ breast cancer subtype that is intrinsically resistant to trastuzumab.
HER-2-directed therapy prolongs both time to disease progression and overall survival when combined with chemotherapy and has become the standard of care for those with HER-2-positive breast cancer in the early and advanced settings.
HER2-targeted therapies have altered the natural history of HER2-positive breast cancer, a trend that will likely further improve with the recent approval of new agents.
HER2-targeting agents, including trastuzumab, lapatinib, trastuzumab emtansine, and pertuzumab, have been approved for the treatment of HER2-positive breast cancer, with trastuzumab also approved for the treatment of HER2-positive gastric cancer.
Human epidermal growth factor receptor-2 (HER-2)-positive breast cancer tends to be aggressive, highly metastatic, and drug resistant and spreads rapidly.
HER2 gene variants, as well as other genes/gene variants, are involved in its overexpression, disease prognosis and in predicting the susceptibility towards HER2 positive breast cancer.
HER2 intratumoral heterogeneity is independently associated with incomplete response to anti-HER2 neoadjuvant chemotherapy in HER2-positive breast carcinoma.
HER2-targeted treatments have improved outcomes in patients with HER2-positive breast cancer in the neoadjuvant, adjuvant, and metastatic settings; however, some patients remain at risk of relapse or death for many years after treatment of early-stage disease.Therefore, new strategies are needed.