Wang J, Zhao Z, Sherrill EH, Peeters M, Wiezorek J, Barber B. A Q-TWiST analysis comparing panitumumab plus best supportive care (BSC) with BSC alone in patients with wild-type KRAS metastatic colorectal cancer. Poster presented at the 2011 ISPOR 16th Annual International Meeting; May 2011. Baltimore, MD. [abstract] Value Health. 2011 May; 14(3):A170.

OBJECTIVES: New treatment improves efficacy and often has toxicities. The quality- adjusted time without symptoms of disease or toxicity (Q-TWiST) analysis incorporates survival, toxicities and quality of life into a single metric providing an integrated measure of clinical benefit. Objective of this study was to use Q-TWiST analysis comparing quality-adjusted survival between patients with chemo-refractory wild-type KRAS metastatic colorectal cancer (mCRC) receiving panitumumab best supportive care (BSC) versus BSC alone. Because the trial design allowed patients on BSc arm to receive panitumumab after disease progression, which may have confounded overall survival (OS), the focus of this analysis was on progression-free survival (PFS).

METHODS: The time spent in the toxicity (grade 3 or 4 adverse events; TOX), time without symptoms of disease or toxicity (TWiST), and relapse (after disease progression; REL) states were estimated, and adjusted using utility weights derived from patient-reported EQ-5D measures. Quality-adjusted PFS was when the utility for REL was zero in the Q-TWiST analysis. Sensitivity analyses were performed in which utility weights (varying from 0 to 1) were applied to TOX and REL health states.

RESULTS: The trial included 463 patients, KRAS status ascertained in 427 (92%) of patients. Of these, 243 (57%) having wildtype KRAS tumours (124 panitumumab BSC, 119 BSC alone) were included in the analysis. Statistically significant difference between groups in quality-adjusted PFS favoured panitumumab BSC (12.3 weeks versus 5.8 weeks, respectively, p0.0001). The difference continued to favour panitumumab BSC for all hypothetical utility weights applied to the TOX health state in sensitivity analyses. Although OS was confounded by 76% of patients in the BSC alone arm receiving panitumumab after disease progression, the difference in quality-adjusted OS was also statistically significant and favoured panitumumab BSC.

CONCLUSIONS: In patients with chemo-refractory wild-type KRAS mCRC, panitumumab BSC significant improved quality-adjusted survival compared with BSC alone.

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