A five-arm, open-label, phase I/lb study to assess safety and tolerability of the oral MEK1/MEK2 inhibitor trametinib (GSK1120212) in combination with chemotherapy or erlotinib in patients with advanced solid tumors.

Abstract

3023 Background: Trametinib, an oral MEK1/MEK2 inhibitor, has demonstrated single-agent clinical activity. In vitro studies of trametinib plus docetaxel (doc), pemetrexed (pem) and erlotinib (erl) showed enhanced growth inhibition of lung cancer cell lines with and without RAS/RAF mutations. Trametinib+doc significantly increased apoptosis compared with either agent alone. Methods: This is a two-part, five-arm, phase I/Ib, open-label study to evaluate the safety and tolerability of trametinib plus doc, erl, pem, pem+carboplatin (pem+carbo), or nab-paclitaxel (nab-pac) (NCT01192165). Part I is dose escalation in patients (pts) with advanced solid tumors; part II is dose expansion in pts with lung and pancreatic cancers. A 3+3 dose-escalation design was used to determine the maximum tolerated dose (MTD) and the recommended phase II regimen (RP2R) for each combination. Dose-limiting toxicities (DLTs) were determined during the first treatment cycle (21 days). Trametinib was started at 0.5 mg/day; chemotherapy was given at full recommended doses. Erl was escalated from 50 mg/day. Pharmacokinetic (PK) samples were collected pre-, and 1, 2, 3 and 6 hours post-dose. Results: As of January 2012, 80 pts have been enrolled across all arms except trametinib+nab-pac. Preliminary exposure results of trametinib+doc, erl, or pem suggest no PK drug-drug interaction. The predominant DLT for trametinib+doc without growth factors (MTD = 0.5 mg+60 mg/m2) was neutropenia. When administered with growth factors, trametinib+doc has been given up to 1.5 mg+75 mg/m2 with no DLTs. The predominant DLTs for trametinib+erl (MTD = 1 mg+100 mg) were diarrhea and mucositis and for trametinib+pem (MTD = 1.5 mg+500 mg/m2) were mucositis and febrile neutropenia. The MTD for trametinib+pem+carbo has not yet been determined. To date there are 5 PRs in the trametinib+doc group and 2 PRs in the trametinib+pem group. An NSCLC expansion cohort for trametinib+pem is enrolling. Conclusions: Trametinib+doc and trametinib+pem have shown acceptable tolerability and initial evidence of clinical activity.