Predictors of long-term responders in patients treated with pazopanib for advanced renal cell carcinoma (aRCC).

Abstract

524 Background: The objective of this study was to characterize the long term responders to pazopanib (PAZ) treatment in aRCC patients treated in a real-world community oncology setting. Methods: This retrospective study used US Oncology’s (USON) iKnowMed electronic health record database (Nov 2009 – Oct 2014), supplemented with chart review. Eligible patients: Age ≥ 18 at first diagnosis of aRCC, treated with PAZ as first-line between 11/1/2009 – 8/31/2012, and had at least 2 office visits during the follow-up period. Patients were excluded if they were enrolled in a clinical trial and diagnosed or treated for other primary cancers during the study period. Long-term responders were defined as patients with progression free survival (PFS) ≥18 months. Predictors of long-term responders to PAZ were assessed using multivariate logistic regression analysis. Results: A total of 153 PAZ patients were included of which, 33 patients (22%) were identified as long-term responders. The median PFS in long-term responders and non-long-term responders was 27.2 months (95% CI: 23.0, 35.2) vs. 6.9 months (95% CI: 5.03-8.55), respectively. Long-term responders were more likely to have Eastern Cooperative Oncology Group (ECOG) score=0 at baseline (42.4% vs. 18.3%, p=0.004), and a history of nephrectomy (81.8% vs. 57.5%, p=0.010) than non-long-term responders. Other patient characteristics including age, gender, or comorbidities did not differ significantly between the two groups even though long-term responders tend to be slightly younger (mean 64.7 vs. 66.2), female (33% vs. 25%), and less likely to have a comorbid condition (36.4% vs. 51.7%) compared to non-long-term responders. In the multivariate analysis, the only predictors of long-term response were ECOG = 0 at baseline (vs. ECOG = 1 (OR: 0.38; 95% CI 0.16-0.89) and vs. ECOG≥2 (OR: 0.07, 95% CI: 0.01-0.54) and history of nephrectomy (OR: 3.33; 95% CI 1.28-8.65). Conclusions: A subset (22%) of PAZ patients had clinically relevant long term responses in a US community oncology setting. ECOG score of 0 and history of nephrectomy were predictors of long term response in PAZ.