Vascular tumor burden as a new quantitative CT imaging biomarker for predicting metastatic RCC response to antiangiogenic therapy.

Academic Article

Abstract

  • 595 Background: Anti-angiogenic (AAG) therapy is designed to devascularize tumors, so we developed methods for measuring the vascular tumor burden (VTB) on CT images. This study was designed to validate initial changes in the VTB as a quantitative CT imaging biomarker for predicting progression-free survival (PFS) in patients with metastatic RCC treated with AAG therapy. Methods: As part of a multi-institutional prospective phase III trial by Motzer et al. NEJM 2009, adult patients with metastatic clear cell RCC were treated with sunitinib (N=375). In this post hoc secondary analysis, quantitative CT imaging software was used to measure the VTB in cm2on baseline and initial post-therapy CT images (N=275 with digital images). Enhancing MASS (eMASS) Criteria response groups included Favorable Risk (FR; 30% decrease in VTB), Intermediate Risk (IR; not FR or UR), or Unfavorable Risk (UR; 20% increase in VTB or new metastases). Initial post-therapy CT images were evaluated by eMASS Criteria, RECIST, Choi Criteria and MASS Criteria. Comparison of PFS among response groups was evaluated using log-rank test and Cox-proportional hazards ratio. Results: Median PFS of the cohort was 1.1 years. Median PFS of the response groups from the criteria are depicted in Table 1. The median difference in PFS (MD) and hazard ratio (HR) for eMASS Criteria IR vs FR (MD=1.2, p<0.001; HR=5.24, 95%CI=3.71-7.41, p<0.001) were substantially higher than for RECIST SD vs PR (MD=0.3, p=0.237; HR=1.42, 95%CI=0.79-2.57, p=0.241), Choi Criteria SD vs PR (MD=0.4, p=0.003; HR=1.86, 95%CI=1.22-2.83, p=0.004), or MASS Criteria IR vs FR (MD=0.2, p=0.051; HR=1.37, 95%CI=1.00-1.89, p=0.052), indicating that patients with eMASS IR were 5 times more likely to progress than patients with FR. Conclusions: A quantitative CT imaging biomarker designed to measure initial changes in the vascular tumor burden is highly predictive of PFS in patients with metastatic RCC treated with AAG therapy. [Table: see text]
  • Digital Object Identifier (doi)

    Author List

  • Smith AD; Zhang X; Souza F; Roda M; Zhang H; Bryan J
  • Start Page

  • 595
  • End Page

  • 595
  • Volume

  • 34
  • Issue

  • 2_suppl