The purpose of the study is to identify molecular markers at the level of molecular pathway activation to predict efficacy of anti-HER2 therapy with Trastuzumab.

Biopsy and/or surgical samples from Her2-positive breast cancer patients treated with Trastuzumab alone or in combinations with other regimens of chemotherapy with known clinical outcomes will be collected and subjected to mRNA sequencing. Expression profiles will be analysed using original bioinformatic platform Oncobox. Based on comparison of molecular pathways activation strength and clinical response to Trastuzumab and chemotherapy, this study aims to identify molecular markers predicting efficacy of therapy with Trastuzumab and the possibility of further relapse.

Inclusion Criteria:

• adult females
• histologically confirmed HER2-positive breast cancer
• available FFPE samples of breast cancer tissue
• patients treated with Trastuzumab alone or in combination(s) with other regimens of chemotherapy with known outcome according to RECIST 1.1
• stage II or more
• patients who have signed an informed consent

Exclusion Criteria:

• less than 70% of intact tumor cells in available FFPE samples

Residents of North-Western and Central Parts of Russian Federation

Study Protocol Statistical Analysis Plan (SAP) NGS data Clinical Study Report (CSR)

Beginning 3 months after trial completion, no end date

Anyone