False suspicion of renal insufficiency with MATE-1 inhibiting tyrosine kinase inhibitors for lung cancer

Select tyrosine kinase inhibitors used to treat oncogene-driven lung cancer also inhibit MATE-1, resulting in retainment of creatinine in serum. Elevated creatinine levels raise false suspicion of renal insufficiency. A study at Memorial Sloan Kettering Cancer Center (New York, NY) found elevated creatinine levels in 90 of 863 TKI-treated lung cancer patients. Concurrently drawn creatinine and cystatin C levels were available for 17 patients. In 15 of 17 patients the glomerular filtration rate (GFR) calculated based on cystatin C was lower than GFR based on creatinine. Using a virtual clinical trial GFR cutoff of 40 ml/min, the percentage of TKI eligible patients rose from 41% using creatinine calculations to 71% using cystatin C calculations. When serum creatinine appears elevated in patients receiving MATE-1 inhibitors, recalculation GFR using cystatin C before stopping TKI therapy is recommended.