Phase II study of the dual EGFR/HER3 inhibitor duligotuzumab (MEHD7945A) vs. cetuximab in combination with FOLFIRI in RAS wild-type metastatic colorectal cancer

PURPOSE: Duligotuzumab is a dual-action antibody directed against EGFR and HER3. EXPERIMENTAL DESIGN: mCRC patients with KRAS ex2 wild-type received duligotuzumab or cetuximab and FOLFIRI until progression or intolerable toxicity. Mandatory tumor samples underwent mutation and biomarker analysis. Efficacy analysis was conducted in patients with RAS exon 2/3 wild-type tumors. RESULTS: Of 134 randomized patients, 98 were RAS ex2/3 wild-type. Duligotuzumab provided no PFS or OR benefit compared to cetuximab; though there was a trend for lower ORR in the duligotuzumab arm. No relationship was seen between PFS or ORR and ERBB3, NRG1, or AREG expression. There were fewer skin rash events for duligotuzumab but more diarrhea. Although the incidence of grade ≥ 3 AEs was similar, the frequency of serious AEs was higher for duligotuzumab. CONCLUSIONS: Duligotuzumab plus FOLFIRI did not appear to improve the outcomes in patients with RAS exon 2/3 wild-type mCRC compared to cetuximab + FOLFIRI

K23CA100691 (to L.G.S.). Patient care

of print at www.jco.org on August 31