564P - Quality-Adjusted Survival in Patients with Wild-Type (WT) Kras Metastatic Colorectal Cancer (MCRC) Receiving First-Line Therapy with Panitumumab Plus Folfox Versus Folfox Alone

Abstract

ABSTRACT Background Panitumumab plus FOLFOX significantly improved progression-free survival (PFS) in patients with WT KRAS mCRC. The objective of this analysis was to use the quality-adjusted time without symptoms of disease or toxicity of treatment (Q-TWiST) method to compare quality-adjusted survival between the treatment arms. Methods Patients with mCRC were randomized to panitumumab plus FOLFOX or FOLFOX alone in a phase III clinical trial. For each treatment arm, the area under the survival curve, which was estimated using the Weibull distribution, was partitioned into health states: toxicity (TOX), time without symptoms of disease progression or toxicity (TWiST, i.e., PFS minus TOX), and relapse period (REL, i.e., overall survival (OS) minus PFS); and adjusted using utility weights derived from patient-reported EuroQoL 5-dimensions measures. The null hypothesis of no difference between treatment groups was tested based on the normal approximation with standard errors calculated by the bootstrap method. Sensitivity analyses were performed using the standard Q-TWiST approach with means restricted to median OS. Results Of 1,183 patients who were randomly assigned, 1,096 patients (93%) had available tumor KRAS status, of which 656 patients (60%) had WT KRAS tumors (panitumumab plus FOLFOX, n = 325; FOLFOX alone, n = 331) and were included in this analysis. Compared to patients treated with FOLFOX alone, the panitumumab plus FOLFOX group had significantly longer quality-adjusted PFS (8.5 versus 7.2 months, respectively; 1.3 additional quality-adjusted months; p = 0.02) and quality-adjusted OS (22.4 versus 18.6 months; 3.8 additional quality-adjusted months; p = 0.04). When analysis was restricted to 24 months follow-up, the Q-TWiST advantage was smaller but still significant (14.0 versus 13.0 months; 1.0 additional quality-adjusted month; p = 0.04). Conclusions This Q-TWiST analysis showed that in patients with previously untreated WT KRAS mCRC, panitumumab plus FOLFOX significantly improved the duration of the quality-adjusted survival compared with FOLFOX alone. Disclosure J. Wang: The study was funded by Amgen Inc. Z. Zhao: Employed and stock owner of Amgen Inc. B. Barber: Employed and stock owner of Amgen Inc. J. Zhang: The study was funded by Amgen Inc. B. Sherrill: The study was funded by Amgen Inc. S. Braun: Employed and stock owner of Amgen Inc. R. Sidhu: Employed and stock owner of Amgen Inc. M. Gallagher: Employed and stock owner of Amgen Inc. J. Douillard: The study was funded by Amgen Inc.