A 62-year-old woman undergoes mastectomy for a 2 cm ER-positive, HER2-negative, grade 2 breast cancer with 4 out of 15 lymph nodes positive. She is started on adjuvant chemotherapy and endocrine therapy. Pertuzumab (anti-HER2) is considered but found inappropriate. Why?

• A Pertuzumab is only for ER-negative tumours
• B Pertuzumab is only used in the neoadjuvant setting
• C Pertuzumab is contraindicated with node-positive disease
• D Pertuzumab requires HER2-positive status for efficacy ✓

Explanation

Pertuzumab (anti-HER2 dimerisation antibody) is effective only in HER2-positive breast cancer. The APHINITY trial demonstrated benefit from adding pertuzumab to trastuzumab + chemotherapy in node-positive HER2-positive patients. In this case, the tumour is HER2-negative, so pertuzumab would have no therapeutic target and is inappropriate. HER2-negative cancers do not express the pertuzumab binding site (HER2 extracellular domain II).

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.