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ABSTRACT: Purpose
The RAS/RAF/MEK/ERK signaling pathway is critical to the development of colorectal cancers, and KRAS, NRAS, and BRAF mutations foster resistance to radiation. We performed a phase I trial to determine the safety of trametinib, a potent MEK1/2 inhibitor, with 5-fluorouracil (5-FU) chemoradiation therapy (CRT) in patients with locally advanced rectal cancer (LARC).Patients and methods
Patients with stage II/III rectal cancer were enrolled on a phase I study with 3+3 study design, with an expansion cohort of 9 patients at the MTD. Following a 5-day trametinib lead-in, with pre- and posttreatment tumor biopsies, patients received trametinib and CRT, surgery, and adjuvant chemotherapy. Trametinib was given orally daily at 3 dose levels: 0.5 mg, 1 mg, and 2 mg. CRT consisted of infusional 5-FU 225 mg/m2/day and radiation dose of 28 daily fractions of 1.8 Gy (total 50.4 Gy). The primary endpoint was to identify the MTD and recommended phase II dose. IHC staining for phosphorylated ERK (pERK) and genomic profiling was performed on the tumor samples.Results
Patients were enrolled to all dose levels, and 18 patients were evaluable for toxicities and responses. Treatment was well tolerated, and there was one dose-limiting toxicity of diarrhea, which was attributed to CRT rather than trametinib. At the 2 mg dose level, 25% had pathologic complete response. IHC staining confirmed dose-dependent decrease in pERK with increasing trametinib doses.Conclusions
The combination of trametinib with 5-FU CRT is safe and well tolerated, and may warrant additional study in a phase II trial, perhaps in a RAS/RAF-mutant selected population.
SUBMITTER: Wu C
PROVIDER: S-EPMC7334091 | biostudies-literature | 2020 Jul
REPOSITORIES: biostudies-literature
Wu Christina C Williams Terence M TM Robb Ryan R Webb Amy A Wei Lai L Chen Wei W Mikhail Sameh S Ciombor Kristen K KK Cardin Dana B DB Timmers Cynthia C Krishna Somashekar G SG Arnold Mark M Harzman Alan A Abdel-Misih Sherif S Roychowdhury Sameek S Bekaii-Saab Tanios T Wuthrick Evan E
Clinical cancer research : an official journal of the American Association for Cancer Research 20200406 13
<h4>Purpose</h4>The RAS/RAF/MEK/ERK signaling pathway is critical to the development of colorectal cancers, and <i>KRAS</i>, <i>NRAS</i>, and <i>BRAF</i> mutations foster resistance to radiation. We performed a phase I trial to determine the safety of trametinib, a potent MEK1/2 inhibitor, with 5-fluorouracil (5-FU) chemoradiation therapy (CRT) in patients with locally advanced rectal cancer (LARC).<h4>Patients and methods</h4>Patients with stage II/III rectal cancer were enrolled on a phase I s ...[more]