Correlation of CA-125 and RECIST evaluation in recurrent ovarian cancer (ROC): Results from a randomized phase III study of trabectedin (T) with pegylated liposomal doxorubicin (PLD) versus PLD alone

Abstract

5550 Background: OVA-301, an open-label, multicenter, randomized phase III study comparing the combination of T and PLD to PLD alone in 672 ovarian cancer patients, showed significant prolongation in Progression-Free Survival (PFS) and higher Objective Response (OR) in the combination arm (T-PLD) by three separate assessments, investigator assessment (IA), independent radiology (IR) and oncology review (IO). The purpose of this analysis is to examine: 1) the impact of early changes in CA-125 over the subsequent best OR by RECIST; 2) the concordance between best OR determined by CA-125 and RECIST; 3) the value of CA-125 to predict radiological response. Methods: Tumor assessments by imaging and CA-125 were performed at baseline, and every 8 weeks during study in both arms. Radiological tumor assessment, regardless of CA-125 changes, determined the study conduct. Early CA-125 changes were those assessed at the first and second evaluation. Analyses were based on “all randomized patients.” Results: Response rate by RECIST (IR)/CA-125 was 28%/48% for T-PLD vs. 19%/33% for PLD. The association between CA-125 and RECIST response was stronger for IA relative to IR/IO, with 79% concordance for both arms, 65% overall positive predictive value (PPV) and 89% negative predictive value (NPV) for IA and 74%/75% concordance, 46%/49% PPV and 93%/92% NPV for IR/IO. Early CA-125 changes were assessed in 514 patients. Early ≥25% CA-125 decreases in the first/second evaluation occurred in 85%/95% of RECIST responders in the T-PLD arm and in 81/82% responders treated with PLD. Conclusions: The predictive value of CA-125 response was high and similar in both arms. The addition of T to PLD resulted in superior efficacy in this patient population as assessed by IA, IR and IO, with a favorable trend for CA-125 response assessment. RECIST response was preceded by a significant CA-125 decrease in a high proportion of patients. [Table: see text]