LAUSR

OBJECTIVES The tyrosine kinase inhibitor crizotinib may affect renal function. The mechanism of this effect is not understood. We aimed to get more insight by measuring renal hemodynamics in patients treated with crizotinib. MATERIALS AND METHODS Renal hemodynamics (i.e. glomerular filtration rate and effective renal plasma flow) were measured with radioactive tracers in three patients with stage IV non small-cell lung cancer during treatment with crizotinib. The results were compared with simultaneous creatinine based renal function measurements in the same patients. RESULTS Patients had been treated with crizotinib between 155 and 320 days at the first measurement. In one patient the measurement was repeated after a total of one year and two months of treatment. All patients had been treated with chemotherapy containing cisplatin before. In these patients true glomerular filtration rate was 64-83% higher than estimated by creatinine based measurements. Filtration fraction, a measure of glomerular pressure, was increased in all three patients. The glomerular pressure was even further increased in a follow-up measurement. CONCLUSION Creatinine-based estimates of GFR on crizotinib may underestimate the true GFR. However, evidence of increased glomerular pressure may increase risk of long term true nephrotoxicity.