Trametinib (GSK1120212)

Trametinib (also known as GSK1120212 or JTP 74057), originally identified as a p15 inductive compound, is a novel and potent allosteric inhibitor of MEK kinase, which exhibits ATP non-competitive inhibition against MEK1 and MEK2 kinase. It has demonstrated broad antitumor activities in a variety of tumor xgenograft models, including HT-29 and COLO205 colorectal tumor cell lines. Trametinib induces expression of p15 and p27, reduces cyclin D1 levels, and causes dephosphorylation of RB protein and G1-phase arrest with a reduction of TS expression in HT-29 cells. It also effectively inhibits p-ERK 1/2 resulting in cell growth inhibition in tumor cell lines harboring B-RAF mutant.

Reference

Akintunde Akinleye, Muhammad Furqan, Nikhil Mukhi, Pavan Ravella and Delong Liu. MEK and the inhibitors: from bench to bedside. Journal of Hematology & Oncology 2013, 6:27

Motoki Watanabe, Yoshihiro Sowa, Mayumi Yogosawa and Toshiyuki Sakai. Novel MEK inhibitor trametinib and other retinoblastoma gene (RB)-reactivating agents enhance efficacy of 5-fluorouracil on human colon cancer cells. Cancer Sci 2013; 104(6): 687-693

A randomized phase II study of the MEK1/MEK2 inhibitor trametinib (GSK1120212) compared with docetaxel in KRAS-mutant advanced non-small-cell lung cancer (NSCLC)dagger.[Pubmed:25722381]

Ann Oncol. 2015 May;26(5):894-901.

BACKGROUND: KRAS mutations are detected in 25% of non-small-cell lung cancer (NSCLC) and no targeted therapies are approved for this subset population. Trametinib, a selective allosteric inhibitor of MEK1/MEK2, demonstrated preclinical and clinical activity in KRAS-mutant NSCLC. We report a phase II trial comparing trametinib with docetaxel in patients with advanced KRAS-mutant NSCLC. PATIENTS AND METHODS: Eligible patients with histologically confirmed KRAS-mutant NSCLC previously treated with one prior platinum-based chemotherapy were randomly assigned in a ratio of 2 : 1 to trametinib (2 mg orally once daily) or docetaxel (75 mg/m(2) i.v. every 3 weeks). Crossover to the other arm after disease progression was allowed. Primary end point was progression-free survival (PFS). The study was prematurely terminated after the interim analysis of 92 PFS events, which showed the comparison of trametinib versus docetaxel for PFS crossed the futility boundary. RESULTS: One hundred and twenty-nine patients with KRAS-mutant NSCLC were randomized; of which, 86 patients received trametinib and 43 received docetaxel. Median PFS was 12 weeks in the trametinib arm and 11 weeks in the docetaxel arm (hazard ratio [HR] 1.14; 95% CI 0.75-1.75; P = 0.5197). Median overall survival, while the data are immature, was 8 months in the trametinib arm and was not reached in the docetaxel arm (HR 0.97; 95% CI 0.52-1.83; P = 0.934). There were 10 (12%) partial responses (PRs) in the trametinib arm and 5 (12%) PRs in the docetaxel arm (P = 1.0000). The most frequent adverse events (AEs) in >/=20% of trametinib patients were rash, diarrhea, nausea, vomiting, and fatigue. The most frequent grade 3 treatment-related AEs in the trametinib arm were hypertension, rash, diarrhea, and asthenia. CONCLUSION: Trametinib showed similar PFS and a response rate as docetaxel in patients with previously treated KRAS-mutant-positive NSCLC. CLINICALTRIALSGOV REGISTRATION NUMBER: NCT01362296.

A phase I/Ib study of trametinib (GSK1120212) alone and in combination with gemcitabine in Japanese patients with advanced solid tumors.[Pubmed:26259955]

Invest New Drugs. 2015 Oct;33(5):1058-67.

BACKGROUND: Trametinib is an inhibitor of MEK1/MEK2 activation and kinase activity. In order to evaluate the safety, tolerability, pharmacokinetics, and preliminary efficacy of single-agent trametinib (part 1) and trametinib in combination with gemcitabine (part 2), we undertook the first clinical study of this combination in Japanese patients with cancer and herein report our results. METHODS: In part 1, 13 patients with advanced solid tumors were enrolled into 3 dose cohorts, receiving trametinib once daily at a dose of 1.0, 2.0, or 3.0 mg. In part 2, 5 patients with pancreatic cancer received trametinib (2.0 mg once daily) in combination with gemcitabine (1000 mg/m(2)). RESULTS: In part 1, a dose-limiting toxicity was observed in a patient in the 2.0-mg dose cohort, but the maximum tolerated dose was not reached at doses up to 3.0 mg daily. The best overall response was a PR in 1 patient, and 6 patients had SD. In part 2, the combination of trametinib and gemcitabine was tolerated for a short period of time. However, serious interstitial lung disease (ILD) was observed in 3 of 5 patients 4 weeks or more after the start of the treatment, including 1 fatal case. Three patients achieved a PR, and 2 patients had SD. The most common adverse event was rash (85 % in part 1 and 100 % in part 2). CONCLUSIONS: Trametinib monotherapy was tolerable in Japanese patients with cancer. However, the combination of trametinib plus gemcitabine carried a higher risk as compared with monotherapy, during which no ILD was observed. (ClinicalTrials.gov number, NCT01324258.).

A phase Ib dose-escalation study of the oral pan-PI3K inhibitor buparlisib (BKM120) in combination with the oral MEK1/2 inhibitor trametinib (GSK1120212) in patients with selected advanced solid tumors.[Pubmed:25500057]

Clin Cancer Res. 2015 Feb 15;21(4):730-8.

PURPOSE: MAPK and PI3K/AKT/mTOR pathways play important roles in many tumors. In this study, safety, antitumor activity, and pharmacokinetics of buparlisib (pan class PI3K inhibitor) and trametinib (MEK inhibitor) were evaluated. EXPERIMENTAL DESIGN: This open-label, dose-finding, phase Ib study comprised dose escalation, followed by expansion part in patients with RAS- or BRAF-mutant non-small cell lung, ovarian, or pancreatic cancer. RESULTS: Of note, 113 patients were enrolled, 66 and 47 in dose-escalation and -expansion parts, respectively. MTD was established as buparlisib 70 mg + trametinib 1.5 mg daily [5/15, 33% patients with dose-limiting toxicities (DLT)] and recommended phase II dose (RP2D) buparlisib 60 mg + trametinib 1.5 mg daily (1/10, 10% patients with DLTs). DLTs included stomatitis (8/103, 8%), diarrhea, dysphagia, and creatine kinase (CK) increase (2/103, 2% each). Treatment-related grade 3/4 adverse events (AEs) occurred in 73 patients (65%); mainly CK increase, stomatitis, AST/ALT (aspartate aminotransferase/alanine aminotransferase) increase, and rash. For all (21) patients with ovarian cancer, overall response rate was 29% [1 complete response, 5 partial responses (PR)], disease control rate 76%, and median progression-free survival was 7 months. Minimal activity was observed in patients with non-small cell lung cancer (1/17 PR) and pancreatic cancer (best overall response was SD). Relative to historical data, buparlisib exposure increased and trametinib exposure slightly increased with the combination. CONCLUSIONS: At RP2D, buparlisib 60 mg + trametinib 1.5 mg daily shows promising antitumor activity for patients with KRAS-mutant ovarian cancer. Long-term tolerability of the combination at RP2D is challenging, due to frequent dose interruptions and reductions for toxicity.

PACMEL: a phase 1 dose escalation trial of trametinib (GSK1120212) in combination with paclitaxel.[Pubmed:25542057]

Eur J Cancer. 2015 Feb;51(3):359-66.

BACKGROUND: We sought to determine the maximal tolerated dose of the MEK inhibitor trametinib with weekly paclitaxel, with a view to exploring the combination's activity in melanoma lacking a BRAF V600 mutation. METHODS: In this phase 1 study we used a fixed dose of paclitaxel (80 mg/m2 intravenous (IV) on days 1, 8 and 15 of each 4 week cycle) and escalated the dose of trametinib (to a maximum 2mg orally (PO) daily), following a 3+3 design. Eligible patients had advanced melanoma and could have received up to two previous lines of treatment for metastatic disease. FINDINGS: 15 patients were enrolled, all but one of whose melanoma was wild type for BRAF at codon 600. The maximal monotherapy dose of trametinib proved tolerable with weekly paclitaxel. The most frequent adverse events observed were rash and fatigue. Six (40%) partial responses were reported, including four of eight patients with NRAS mutations. Median progression free survival was 5.5 months (95% confidence interval (CI) 1.8-7.8 months) and overall survival, 14.1 months (95% CI 4.6-not reached). INTERPRETATION: Trametinib can safely be given with weekly paclitaxel at the full monotherapy dose. In this small group promising progression free and overall survival were observed in patients with melanoma lacking a V600 BRAF mutation.