Updated efficacy of the MEK inhibitor trametinib (T), BRAF inhibitor dabrafenib (D), and anti-EGFR antibody panitumumab (P) in patients (pts) with BRAF V600E mutated (BRAFm) metastatic colorectal cancer (mCRC).

103 Background: BRAF V600E mutations occur in 5–10% of mCRC and confer a poor prognosis. Unlike BRAFm melanoma, BRAF and MEK inhibitors have minimal activity in BRAFm mCRC. Preclinical data suggest that combined inhibition of the EGFR and MAPK pathways is required to maximally inhibit growth of BRAFm mCRC. This study evaluates the activity of the combination of P with D and/or T in BRAFm mCRC. Methods: Eligible pts with BRAFm mCRC received doublet, D+P or T+P, or triplet, D+T+P. Results: Doublet (D+P): 20 pts received the full doublet dose (D 150mg twice daily [BID] + P 6mg/kg every 2 weeks [Q2W]). Triplet: 35 pts received D+T+P including 24 pts that received full triplet dose (D 150mg BID + T 2mg once daily [QD] + P 6mg/kg Q2W). No dose-limiting toxicities were observed. As of October 20, 2014, the most common adverse events were dermatitis acneiform (Grade [G] 1/2 55%) and fatigue (G 1/2 45%) for D+P, and diarrhea (G1/2 60%, G3 9%) and dermatitis acneiform (G1/2 47%; G3 9%) for triplet. The confirmed re...