J Clin Pharm Ther. 2019;00:1–6. wileyonlinelibrary.com/journal/jcpt | 1 © 2019 John Wiley & Sons Ltd Received: 13 May 2019 | Revised: 1 October 2019 | Accepted: 18 October 2019 DOI: 10.1111/jcpt.13071 ORIGINAL ARTICLE Elevation in serum uric acid levels predicts favourable response to erlotinib treatment in patients with metastatic non-small-cell lung cancer Fatih Selcukbiricik MD 1 | Elif Ozdogan MD 2 | Tuncay Dagel MD 3 | Serhan Tanju MD 4 | Suat Erus MD 5 | Lale A. Ertuglu MD 2 | Murat Kapdağlı MD 6 | Deniz Tural MD 7 | Ahmet Bilici MD 8 | Sukru Dilege MD 4 | Nil M. Mandel MD 1,9 | Mehmet Kanbay MD 10 1 Department of Medical Oncology, Faculty of Medicine, Koc University, Istanbul, Turkey 2 Koc University School of Medicine, Istanbul, Turkey 3 Department of Nephrology, Koc University Hospital, Istanbul, Turkey 4 Department of Thoracic Surgery, Faculty of Medicine, Koc University, Istanbul, Turkey 5 Department of Thoracic Surgery, Koc University Hospital, Istanbul, Turkey 6 Department of Thoracic Surgery, VKV American Hospital, Istanbul, Turkey 7 Department of Medical Oncology, Bakırköy Sadi Konuk Education and Training Hospital, Istanbul, Turkey 8 Department of Medical Oncology, Faculty of Medicine, Medipol University, Istanbul, Turkey 9 Department of Medical Oncology, VKV American Hospital, Istanbul, Turkey 10 Department of Nephrology, Faculty of Medicine, Koc University, Istanbul, Turkey Correspondence Fatih Selcukbricik, Department of Oncology, School of Medicine, Koc University, Sariyer, Istanbul 34590, Turkey. Email: fselcukbiricik@ku.edu.tr Funding information Republic of Turkey Ministry of Development Abstract What is known and objective: Erlotinib is a small molecule tyrosine kinase inhibitor which blocks the activation of epidermal growth factor receptor (EGFR), a transmem- brane receptor that is upregulated in many cancer types. Inhibition of angiogenesis with consequent impairments in intratumoral microcirculation is one of the mecha- nisms through which EGFR inhibition halts the progression of cancer. A consequence of impaired microcirculation is intratumoral hypoxia, which results in increases in serum uric acid levels. The goal of this study was to investigate the relationship be- tween serum uric acid levels and response to erlotinib in metastatic non-small-cell lung cancer (NSCLC). Methods: A total of 56 patients with metastatic non-small-cell lung cancer who re- ceived erlotinib for a duration of at least 3 months were included in this retrospective cohort study. Demographic characteristics, progression status, baseline serum uric levels and 3-month serum uric acid levels were recorded and analysed. Results and discussion: Of the study population, 21 (37.5%) were female and 35 (62.5%) were male patients. No significant difference in above demographic charac- teristics was observed among exitus, survivor with progression and survivor without progression groups. Patients who responded favourably to erlotinib with no progres- sion of their disease had significantly increased uric acid levels at 3-month follow-up (P = .01). Such a correlation was not observed if the patient was exitus (P = .47) or had progressed on erlotinib therapy (P = .19). What is new and conclusion: In conclusion, this study is the first to demonstrate significant increases in serum uric acid levels in patients with metastatic NSCLC who responded favourably to erlotinib and had no progression under erlotinib therapy. Further studies are required to confirm and characterize serum uric acid as a novel biomarker in predicting the outcome in those with metastatic NSCLC. KEYWORDS erlotinib, lung cancer, uric acid