A phase I study of MEK162 and FOLFOX in chemotherapy-resistant metastatic colorectal cancer.

679 Background: Pre-clinical studies have shown that the combination of MEK inhibitors and 5-FU improves antitumor activity and that MEK inhibition overcomes both 5FU and platinum resistance. This phase I study was conducted to determine the maximum tolerated dose (MTD) of the combination MEK162 and FOLFOX. Methods: Patients (pts) with metastatic colon or rectal cancer who progressed or failed prior 5FU, irinotecan, oxaliplatin and anti-EGFR therapy (in cases of RAS wild type tumors) received twice daily MEK162 in combination with every-2-week FOLFOX. Two dose levels of MEK162 (30mg and 45mg) were investigated in a standard 3 + 3 escalation design in combination with standard doses of FOLFOX without bolus 5-FU. Dose limiting toxicity (DLT) was defined as any treatment-related grade (G) 3 or 4 non-hematological toxicity (with the exception of G3 diarrhea or vomiting < 48 hrs) or G 4 neutropenia or thrombocytopenia within the first 2 cycles (4 weeks) of the treatment. Limited pharmacokinetic (PK) analysis o...