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MO18 - NSCLC - Targeted Therapies IV (ID 116)
- Event: WCLC 2013
- Type: Mini Oral Abstract Session
- Track: Medical Oncology
- Presentations: 1
MO18.10 - Oral MEK1/MEK2 inhibitor trametinib (GSK1120212) in combination with pemetrexed in a phase 1/1B trial involving <em>KRAS</em>-mutant and wild-type (WT) advanced non-small cell lung cancer (NSCLC): efficacy and biomarker results (ID 2922)
16:15 - 17:45 | Author(s): D.A. Richards
KRAS is the most frequently mutated oncogene in NSCLC and represents an unmet need for targeted therapy. Trametinib plus pemetrexed enhances growth inhibition and apoptosis of NSCLC cell lines with and without RAS/RAF mutations in vitro when compared with either agent alone.
This 2-part, multi-arm, open-label phase 1/1B study evaluated the safety and efficacy of trametinib plus chemotherapy (NCT01192165). Part 1 determined the recommended phase 2 dose (RP2D) for trametinib (1.5 mg daily) and pemetrexed (500 mg/m every 3 weeks) in patients with advanced solid tumors. In part 2, patients with NSCLC were stratified as KRAS WT or KRAS-mutant and treated at the RP2D. Primary study objectives were safety and tolerability; secondary objectives were efficacy and pharmacokinetics (PK). Next-generation sequencing was used to perform exploratory mutational profiling on available archival tissue from 21 patients (50%). Plasma from 38 patients (90%) was analyzed both for tumor-derived mutations in cell-free DNA (eg, KRAS, EGFR) using BEAMing technology as well as cytokine and angiogenic factors using a Searchlight multiplex assay.
A total of 42 patients with NSCLC (19 KRAS WT [79% ≥ 2 prior therapies; 74% prior pemetrexed; 16% squamous] and 23 KRAS-mutant [57% ≥ 2 prior therapies; 43% prior pemetrexed; 4% squamous]) were enrolled and treated at the RP2D until disease progression or unacceptable toxicity. Safety and PK data were previously reported (ASCO 2013). Response rate was 17% and disease control rate was 69% for the whole population of NSCLC. Of note, we observed disease control in 75% of patients previously treated with pemetrexed (including 4 partial responses [PRs]) and in 2 patients out of 4 with squamous histology (including one PR). Progression-free survival (PFS) was 5.1 months for all patients with NSCLC. Detailed efficacy results according to mutation status are shown in Table 1. Among KRAS WT, activity was seen in cancers with EGFR mutations or ALK rearrangement. Final biomarker analyses, including assessment of their potential correlation with therapeutic response or resistance, are ongoing and will be reported upon completion. Figure 1
MEK inhibition with trametinib + pemetrexed demonstrated activity in both KRAS-mutant and WT NSCLC; efficacy data are encouraging and warrant further study. There was no significant difference in activity or efficacy across KRAS mutation subtypes. Interestingly, activity with this combination was broad and was seen in patients with squamous histology, patients with prior pemetrexed treatment, and those with EGFR mutation or ALK translocation.
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