HER2-positive breast cancer with brain, skin, and lymph-node metastases responding to dual-targeted therapy

What happened, in summary

This 51-year-old woman had HER2-positive invasive ductal carcinoma of the left breast treated initially with modified radical mastectomy on April 21, 2021. Pathology showed a 4.6 cm grade II tumor with vascular invasion and 14 of 21 axillary lymph nodes involved, staged pT2N3M0, Stage IIIC. The tumor was ER-negative, PR-negative, HER2 IHC 3+, and Ki-67 30%. After surgery, she received 6 rounds of docetaxel and carboplatin combined with trastuzumab and pertuzumab, then entered follow-up every 3 to 6 months. Three years later, in April 2024, she developed redness, swelling, and warmth of the left upper limb and hand. It was treated as erysipelas with 1 week of IV cephalosporin antibiotics, and the swelling partly improved. In May 2024, dizziness, headache, nausea, vomiting, and rising CEA and CA125 led to brain MRI, which showed multiple brain metastases. Whole-brain radiotherapy was performed on June 5, 2024. During radiation, erythematous skin lesions spread across the left chest wall, left upper limb, and right breast. PET/CT showed brain and left cervical lymph-node metastases, and chest-wall skin biopsy confirmed metastatic breast cancer that remained ER-negative, PR-negative, and HER2 IHC 3+, with Ki-67 70%. On June 30, she began inetetamab trastuzumab, pyrotinib, and capecitabine. After 1 cycle, skin lesions shrank and darkened, tumor markers fell, and the largest brain metastasis decreased by about 46%, consistent with partial response. As of September 2024, her disease remained stable on treatment. PET/CT did not show abnormal FDG uptake in the lungs, liver, bones, uterus, or gallbladder.