591P - Impact of primary tumour side on 3-year survival outcomes of first-line (1L) FOLFOX-4 ± cetuximab in patients with RAS wild-type (wt) metastatic colorectal cancer (mCRC) in the phase III TAILOR trial

The TAILOR trial demonstrated a significant survival advantage with the addition of cetuximab to 1L FOLFOX-4 in patients from China with RAS wt mCRC and met all of its endpoints. We report the impact of primary tumor side on 3-year overall survival (OS) in TAILOR. TAILOR was a randomized, open-label, multicenter, phase 3 trial that evaluated 1L cetuximab + FOLFOX-4 vs FOLFOX-4 in patients from China with RAS wt mCRC. The primary endpoint was progression-free survival time, as determined by independent review committee; secondary endpoints included OS time, ORR, and safety/tolerability. Tumors were categorized in evaluable patients as left (L)-sided (splenic flexure, descending colon, sigmoid colon, and rectum) or right (R)-sided (appendix, cecum, ascending colon, hepatic flexure, and transverse colon). Of the 393 treated patients with RAS wt mCRC, median follow-up time was 57.0 months (range, 1.5–75.5), and 391 patients were evaluable for tumor side. Median OS and 3-year OS rates by primary tumor side are summarized in the table.Table591PTablePrimary tumor side: LPrimary tumor side: RCetuximab + FOLFOX-4 (n=146)FOLFOX-4 (n=162)Cetuximab + FOLFOX-4 (n=45)FOLFOX-4 (n=38)Median OS (95% CI), months22.0 (18.7–25.5)18.3 (15.2–20.2)11.5 (7.5–20.4)9.4 (7.5–18.8)3-year OS rate (95% CI), %32 (25–40)16 (11–22)23 (11–38)14 (5–28) This updated analysis at>4.5 years’ median follow-up is consistent with previous results from the TAILOR study, which showed improved OS with the addition of cetuximab to FOLFOX-4. Indeed, the 3-year OS rate was doubled in patients with L-sided mCRC and > 1.5 times higher in those with R-sided disease, showing that patients with mCRC might benefit from treatment with cetuximab irrespective of primary tumor side. Overall, these results confirm cetuximab in combination with FOLFOX-4 as an effective standard-of-care 1L therapy for patients with RAS wt mCRC. NCT01228734; EMR62202-057. Medical writing assistance (funded by Merck Healthcare KGaA, Darmstadt, Germany) was provided by Marjorie Rummelt, PhD, of ClinicalThinking, Inc, Hamilton, NJ, USA. Merck Healthcare KGaA. Merck Healthcare KGaA. J. Nippgen: Full / Part-time employment: Merck Serono. W. Chen: Full / Part-time employment: Merck Serono. J. Li: Research grant / Funding (institution): Merck; Research grant / Funding (institution): Roche. All other authors have declared no conflicts of interest.