Working together for the family: HER oncogenes co-amplification in breast cancer

LAURITO SERGIO; BRANHAM MARÍA TERESITA; EMANUEL CAMPOY; REAL SEBASTIAN; CUETO JUAN; GAGO FRANCISCO; GLATSTEIN TELMA; DE LA IGLESIA PAOLA; MARIA ROQUE MORENO

Virtual

Simposio; Buenos Aires Breast Cancer Symposium BA-BCS2021; 2021

IBYME- BA-BCS2021

HER2 overexpressing tumors represent 15-20% of invasive ductal breast carcinomas(IDC). Even though they are treated with the monoclonal antibody trastuzumab, 20% ofprimary and 70% of metastatic HER2 tumors develop resistance. HER2 belongs to a 4-member oncogene family (HER1-4), which present the capacity to compensate inhibition.We believe it is relevant to know the state of the whole family to predict response to treatment. Here we have designed a probe mix to detect the amplification of the 4 HER oncogenes. One hundred and eleven IDC (54 fresh frozen and 57 FFPE) were analyzed byMLPA, and HER2 determination was validated prospectively by FISH, IHQ and CISH(Pearson r=0.95; 0.59; 0.97 respectively, p