Long-term erlotinib treatment alongside worsening kidney vasculitis

What happened, in summary

A 71-year-old man was diagnosed with non-small cell lung cancer in the left lower lobe in 2006. He underwent left lower lobectomy and lymph-node dissection for pT4N2M0, stage IIIB disease. Over the following years, he received several systemic treatments. Gefitinib caused severe diarrhea and an episode of acute kidney injury. Pemetrexed was later stopped when the cancer progressed.

Erlotinib 150 mg daily was started in 2016. Three months later, bone metastases showed osteosclerotic change, which was considered evidence that treatment was helping. After one year, creatinine increased, so erlotinib was reduced to every other day.

At two years and three months, he developed protein and blood in the urine. Testing showed an elevated MPO-ANCA level, and kidney biopsy was performed. Because the initial vasculitis activity appeared limited and stopping erlotinib could worsen his lung-cancer outlook, the drug continued with close monitoring.

Eleven months later, inflammation and MPO-ANCA rose sharply. A second biopsy showed more advanced kidney damage and findings consistent with ANCA-associated vasculitis. He received three days of high-dose intravenous methylprednisolone followed by oral prednisone. The antibody level fell after treatment.

Erlotinib remained part of his cancer care because he continued to benefit from it. His case required balancing control of metastatic lung cancer against a progressively serious renal complication that may have been aggravated by long-term EGFR inhibition.