Abstract CT110: Randomized phase II study of duligotuzumab + FOLFIRI versus cetuximab + FOLFIRI in 2nd-line patients with KRAS wild-type (wt) metastatic colorectal cancer (mCRC)

Abstract

Abstract Background: Duligotuzumab (MEHD, MEHD7945A) is a novel dual-action humanized IgG1 antibody that blocks EGFR and HER3 binding, inhibiting all major ligand-dependent HER complex signaling. MEHD is active in multiple tumor models, including models resistant to anti-EGFR or anti-HER3. Emerging data in CRC suggest a role for HER3 in de novo and acquired resistance to anti-EGFR therapy. Methods: This open-label, randomized Phase II study enrolled patients (pts) with KRAS exon 2 wt mCRC who progressed on/after oxaliplatin-containing chemotherapy. Pts received a combination of MEHD (1100 mg IV, q2w) or cetuximab (400 mg/m2 load, 250 mg/m2 IV, q1w) + FOLFIRI (q2w) until progression or intolerable toxicity. Endpoints included progression-free survival (PFS), and objective response rate (ORR), overall survival (OS), and adverse events (AEs). Tumor samples were mandatory and underwent biomarker analysis for ERBB3, NRG1 and EGFR ligand expression by qRT-PCR, and ERBB3 by IHC. The primary efficacy analysis was conducted in patients with RAS wt tumors (no mutations detected in KRAS or NRAS exons 2, 3; exon 4 mutations pending). Results: Of 134 randomized patients, 98 were RAS ex2/3 wt (53 MEHD); median age 63 years, ECOG 0-1. As of 21Aug14, 11 pts remain active. Efficacy results (Table) show no benefit of MEHD + FOLFIRI; ORR was lower in the MEDH arm. No relationship was seen between PFS or ORR and mRNA expression for ERBB3 or NRG1, or ERB3 expression by IHC. There were fewer rash events of any grade in the MEHD arm (79% and 93%) but more diarrhea (89% and 66%). Incidence of Grade ≥ 3 AEs was similar between arms (87% and 89%); however, the frequency of SAEs was higher in the MEHD arm (55% and 48%). Cumulative dose intensity and duration of treatment with FOLFIRI were lower in the MEHD arm. Conclusions: MEHD + FOLFIRI did not improve outcomes of pts with RAS ex2/3 wt mCRC compared to cetuximab + FOLFIRI. Updated efficacy, safety and biomarker data will be presented. All ptsMEHD7945A + FOLFIRICetuximab + FOLFIRIHazard Ratio or Odds Ratio (90% CI)(n = 53)(n = 45)PFS events39 (74%)33 (73%)1.40 (0.94-2.08)Median PFS, mo (90% CI)6.9 (4.9-7.6)5.7 (5.5-7.7)OS events18 (34%)19 (42%)0.85 (0.49-1.46)Median OS, mo (90% CI)NE (12.0-NE)12.4 (10.0-NE)ORR,% (90% CI)17.0 (9.8-26.6)33.3 (21.8-46.1)0.41 (0.18-0.91)CI = confidence interval. NE = not estimated Citation Format: Andrew G. Hill, Michael Findlay, Matthew Burge, Christopher Jackson, Pilar Garcia Alfonso, Leslie Samuel, Vinod Ganju, Meinolf Karthaus, Alessio Amatu, Mark Jeffery, Maria DiBartolomeo, John Bridgewater, Andrew Coveler, Manuel Hidalgo, Amy V. Kapp, Roxana Sufan, Bruce McCall, Elicia Penuel, Andrea Pirzkall, Josep Tabernero. Randomized phase II study of duligotuzumab + FOLFIRI versus cetuximab + FOLFIRI in 2nd-line patients with KRAS wild-type (wt) metastatic colorectal cancer (mCRC). [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT110. doi:10.1158/1538-7445.AM2015-CT110