Pazopanib-Induced Liver Toxicity in Patients With Metastatic Renal Cell Carcinoma: Effect of UGT1A1 Polymorphism on Pazopanib Dose Reduction, Safety, and Patient Outcomes

Treatment of patients with metastatic renal cell carcinoma with pazopanib has been associated with an increased probability of developing liver toxicity in the presence of polymorphisms in the gene UGT1A1 (uridine diphosphate glucuronosyltransferase 1A1), leading to treatment interruptions and permanent discontinuation. We have demonstrated that UGT1A1-guided dosing can manage pazopanib-induced liver toxicity and also that UGT1A1 polymorphisms are associated with improved outcomes, despite pazopanib interruption and substantial dose reductions. Background: Pazopanib can induce liver toxicity in patients with metastatic renal cell carcinoma (mRCC). We assessed the effect of a TA repeat polymorphism in the UGT1A1 (uridine diphosphate glucuronosyltransferase 1A1) gene encoding uridine diphosphate glucuronosyltransferase 1A1 on liver toxicity, dose reductions, and patient outcomes. Patients and Methods: Patients with mRCC treated with first-line pazopanib developing liver toxicity underwent genotyping for the UGT1A1 polymorphism. Liver toxicity was assessed using the Common Terminology Criteria for Adverse Events, version 4.0. Progression-free survival and overall survival were assessed using the Kaplan-Meier and log-rank methods. Results: Of 261 patients, 34 (13%) had developed liver toxicity after a median of 29 days (range, 5-155 days). Grade 4, 3, and 2 alanine aminotransferase or bilirubin had increased in 2 (6%), 17 (50%), and 8 (24%) patients, respectively. The UGT1A1 assessment demonstrated that 18 patients (53%) had TA6/TA7, 7 (21%) had TA7/TA7, and 9 (26%) had wild-type TA6/TA6. The UGT1A1 polymorphism was associated with improved median progression-free survival (TA6/TA6, 5.5 months; TA6/TA7, 34.2 months; TA7/TA7, 22.3 months; unknown UGT1A1 status, 9.2 months; UGT1A1 polymorphisms combined vs. unknown status, P =.021). UGT1A1 polymorphism was associated with improved median overall survival (TA6/TA6, 8.1 months, TA6/TA7 or TA7/TA7 not reached, unknown UGT1A1 status, 16.6 months; UGT1A1 polymorphisms combined vs. unknown status, P = .033). Patients with UGT1A1 polymorphism safely resumed pazopanib at ultra-low doses determined by the degree of liver toxicity and UGT1A1 polymorphism. Conclusions: UGT1A1 polymorphisms were associated with improved outcomes, despite pazopanib interruption and dose reductions. UGT1A1 assessment could improve the management of pazopanib-induced liver toxicity in patients with mRCC. (C) 2019 The Author(s). Published by Elsevier Inc.