Abstract
BACKGROUND: Pazopanib is an oral tyrosine-kinase inhibitor that is approved by the U.S. Food and Drug Administration for treatment of metastatic renal cell carcinoma (mRCC). Pharmacokinetic data have shown that concomitant administration of pazopanib and esomeprazole, a proton pump inhibitor (PPI), leads to decreased area under the curve and thus decreased exposure of pazopanib by 40%. Despite the pharmacokinetic data published to date, the clinical significance and impact on patient outcomes resulting from decreased pazopanib exposure remains unknown. MATERIALS AND METHODS: In this retrospective, observational, cohort study, 90 patients with mRCC who either received pazopanib in combination with a PPI or histamine 2 receptor antagonist (H2RA; concurrent PPI/H2RA group) or who did not take concurrent pH-elevating medications (no PPI/H2RA group) were compared to determine if there was an impact on progression-free survival (PFS), the primary endpoint, and secondary endpoints, overall survival (OS) and safety. RESULTS: The differences between the PFS of 9.0 months and OS of 28.0 months for the concomitant PPI/H2RA group versus 11.0 months and 30.1 months, respectively, for the no PPI/H2RA group were not statistically significant. Rates of adverse events were similar between the concomitant PPI/H2RA and no PPI/H2RA groups. CONCLUSION: Concomitant PPI or H2RA usage was not shown to be associated with a reduction in PFS or OS for patients receiving pazopanib for mRCC, with a similar toxicity profile in each group. Based on the results of this retrospective cohort study and the palliative nature of the treatment of patients with mRCC, clinicians should consider allowing patients to remain on concomitant pazopanib and acid-reducing therapy. IMPLICATIONS FOR PRACTICE: Pazopanib is a preferred category-one first-line treatment for predominant clear cell metastatic renal cell carcinoma (mRCC). However, because of an aging demographic, coupled with patients with mRCC presenting with multiple comorbidities, including symptomatic dyspepsia or gastroesophageal reflux disease, patients are commonly required to take pazopanib concomitantly with a proton pump inhibitor (PPI) or a histamine 2 receptor antagonist (H2RA). Despite earlier pharmacokinetic reports suggesting that an alkaline pH may result in poorer absorption, this institutional retrospective study found no effect on clinical outcomes. These data suggest that concurrent treatment of mRCC with pazopanib and a PPI or H2RA may be safe in everyday practice.