What happened, in summary

A 59-year-old woman with infiltrating ductal breast cancer had metastatic disease involving the lungs, spine, left adrenal gland, skull, orbit, and skull base. Her cancer was estrogen-receptor positive, progesterone-receptor positive, and HER2-positive. She had already required spinal surgery to stabilize pathological vertebral fractures and was started on letrozole and intravenous trastuzumab for metastatic breast cancer.

After the initial trastuzumab loading dose, she developed eye irritation, crusting, and rapidly worsening vision. Examination showed severe damage to both corneas, including a perforated ulcer in the left eye. Infection and autoimmune testing did not identify another clear cause, raising strong concern that trastuzumab had contributed to the injury.

She underwent emergency corneal transplantation and required intensive eye treatment. Trastuzumab was stopped in coordination with oncology. Because the first graft failed to heal properly, she needed a second corneal transplant 3 months later. That graft eventually healed over the following year, and no further corneal melts were reported after trastuzumab was discontinued. At the time trastuzumab was stopped, she was living with widespread metastatic breast cancer while the severe eye complication required ongoing treatment.