A recent case report described the development of a complex renal cyst about 6 months after the start of crizotinib treatment in a 49-year-old female with ALK-positive NSCLC.21 Crizotinib was continued due to ongoing clinical benefit, and the complex renal cyst regressed 22 months later despite continuing treatment. The gene discussed is ALK; the disease is non-small cell lung carcinoma.