Final results from study 181: Randomized phase III study of FOLFIRI with or without panitumumab (pmab) for the treatment of second-line metastatic colorectal cancer (mCRC).

Abstract

387 Background: In the primary analysis of study 181, pmab+FOLFIRI significantly improved progression-free survival (PFS) vs FOLFIRI as second-line therapy in patients (pts) with wild-type (WT) KRAS mCRC. Here, we report the results of a prespecified final descriptive analysis planned for 30 months (mos) after the last pt was enrolled. Methods: Pts were randomised 1:1 to pmab 6.0 mg/kg Q2W+FOLFIRI (Arm 1) vs FOLFIRI alone (Arm 2). Pts had one prior fluoropyrimidine-based chemotherapy regimen for mCRC and ECOG 0-2. The co-primary endpoints were PFS (central assessment) and OS, and were independently tested. Secondary endpoints included objective response rate (ORR), and safety. KRAS status was determined by a blinded central lab. Results: 1,186 pts were randomised and received treatment (tx): 591 in Arm 1, 595 In Arm 2. 1,083/1,186 pts (91%) had KRAS results. Adverse event rates were consistent with the primary analysis. Results are shown in the table . Conclusions: In Arm 1, PFS (standard and on-treatment definition) and ORR were improved, and there was a trend toward improved OS in pts with WT KRAS mCRC. The large proportion of pts receiving post-progression anti-EGFR therapy may have affected the ability to observe a difference in OS between the tx arms. In pts with MT KRAS there was no difference in efficacy. KRAS testing is critical to select appropriate pts for tx with pmab. [Table: see text]