Eyelash trichomegaly secondary to panitumumab therapy (2025)

1. CASE DESCRIPTION

We report a recently encountered toxicity of therapy targeting the epidermal growth factor receptor (egfr) that may be of interest to the wider community of oncologists.

A 78-year-old woman was referred to our cancer centre with stage iv metastatic colorectal cancer. At initial surgery, omental metastases had been found, and she had been treated with multiple courses of adjuvant chemotherapy, including folfox–bevacizumab, folfiri–bevacizumab, and most recently, cetuximab for 4 months, with progression of disease and no skin rash. She was then treated with folfox and panitumumab for 6 cycles, with improvements noted on tumour markers and radiographic imaging. Approximately 8 weeks into therapy, she developed significant lengthening and overgrowth of her eyelashes, requiring frequent trimming (Figures 1 and 2).

2. DISCUSSION

Monoclonal antibodies targeting egfr are used in the therapy of multiple cancers. Panitumumab (Vectibix: Amgen, Thousand Oaks, CA, U.S.A.) is a fully humanized monoclonal immunoglobulin G2 antibody specific to egfr, currently approved for the treatment of metastatic colorectal cancer. It is the subject of several clinical trials involving head-and-neck, non-small-cell lung, gastric, esophageal, and pancreatic cancers 1.

Skin toxicity, the most common side effect of anti-egfr monoclonal antibodies, occurs in approximately 90% of patients receiving panitumumab 2. Generally, this toxicity manifests as a follicular eruption on face and trunk, and is considered to be indirect marker of anti-egfr activity.

Trichomegaly connotes thick, curly, rigid eyelashes. The several reported cases of mild eyelash lengthening with cetuximab and erlotinib therapy 3^–5 are believed to be attributable to egfr inhibition in the hair follicles, leading to premature maturation (terminal differentiation) 3. According to the manufacturer, eyelash growth occurs in 6% of patients treated with panitumumab, although most cases are mild 6.

Trichomegaly may obscure vision and has been reported to cause eyelid irritation, including plugging of the meibomian glands and infection. In most cases, eyelash trimming is sufficient, although systemic antibiotics and artificial tears may sometimes be necessary for local irritation or meibomitis 5. Inhibitors of egfr may also cause ocular surface toxicity, including erosions and conjunctival hyperemia because of disruption of corneal egfr. Oncologists should be cognizant of these potential sequelae, for which referral to an ophthalmologist or dermatologist may sometimes be helpful.

Footnotes

4. REFERENCES