3022 - Cell-Free DNA to Detect Focal Versus Non-Focal MET Amplification in Metastatic Colorectal Cancer Patients: Combined Analysis from Japan and the United States

Background

MET amplification (amp) is rare in untreated metastatic colorectal cancer (mCRC), but cell-free DNA (cfDNA) analysis identifies it in ∼20% with anti-EGFR monoclonal antibody (mAb)-refractory disease. CfDNA analysis reveals both focal gene amp and gene copy number gain due to chromosomal aneuploidy (non-focal MET amp). We analyzed cfDNA from Japanese (JPN) and United States (US) patients (pts) with anti-EGFR mAb-refractory mCRC to investigate the prevalence of focal and non-focal MET amp.

Methods

We studied MET amp in pts with mCRC in the Nationwide Cancer Genome Screening Project in JPN (GOZILA; UMIN000029315; JPN cohort) and in a phase I/II trial of cabozantinib (C) +/- panitumumab (P) in pts with RAS wild-type mCRC (NCT02008383; US cohort). MET amp was detected with the Guardant360 assay. Focal MET amp was defined as either the only amp on chromosome (chr) 7q or MET copy number ³4. Non-focal MET amp was defined as co-amp with ³1 other genes (CDK6 or BRAF) located on chr 7q and MET copy number <4.

Results

244 JPN cohort pts were analyzed from 2/2018-12/2018, and 81 pts in the US cohort, from 8/2014-2/2018. In pts with prior anti-EGFR mAb (JPN: n = 184; US: n = 70), focal and non-focal MET amp were detected in 8 (4.3%) and 30 (16.3%) pts in the JPN cohort, and in 9 (12.9%) and 4 (5.7%) US pts. Without prior anti-EGFR mAb (JPN: n = 60; US: n = 11), focal and non-focal MET amp were detected in 1 (1.7%) and 4 (6.7%) pts in the JPN cohort, and 0 (0%) and 1 (9.1%) US pts. The focal MET amp rate combined was 6.7% (17/254) with prior anti-EGFR mAb. In the US cohort, 4/6 pts with focal MET amp treated with C or C+P had a reduction in RECIST lesions as best response, with one PR, while 2 pts with non-focal MET amp had tumor growth as best response.

Conclusions

The prevalence of focal MET amp detected by cfDNA analysis in mCRC pts was similar in the JPN and US cohorts. Given preliminary efficacy results from the US trial, focal MET amp may be a [A1] predictor of benefit from a MET inhibitor. A clinical trial evaluating a MET inhibitor in mCRC pts with focal MET amp is underway.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

A. Kawazoe: Honoraria (self), Research grant / Funding (institution): Ono Oharmaceutical; Honoraria (self), Research grant / Funding (institution): Taiho Pharmaceutical; Research grant / Funding (institution): Dainippon Sumitomo Pharma; Research grant / Funding (institution): Takeda Pharmaceutical; Research grant / Funding (institution): Astellas Pharmaceutical; Research grant / Funding (institution): MSD. Y. Nakamura: Research grant / Funding (institution): Ono Pharmaceutical; Research grant / Funding (institution): Taiho Pharmaceutical. J.I. Odegaard: Full / Part-time employment: Guardant Health. M.I. Lefterova: Full / Part-time employment: Guardant Health. R. Lanman: Full / Part-time employment: Guardant Health. T. Yoshino: Research grant / Funding (institution): Novartis Pharma K.K.; Research grant / Funding (institution): MSD.K.K.; Research grant / Funding (institution): Sumitomo Dainippon Pharma Co., Ltd.; Research grant / Funding (institution): CHUGAI PHARMACEUTICAL CO., LTD.; Research grant / Funding (institution): Sanofi K.K.; Research grant / Funding (institution): DAIICHI SANKYO COMPANY, LIMITED; Research grant / Funding (institution): PAREXEL International Inc.; Research grant / Funding (institution): ONO PHARMACEUTICAL CO., LTD.. J.H. Strickler: Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Amgen; Honoraria (self), Advisory / Consultancy: Bayer; Honoraria (self): Chugai; Honoraria (institution), Advisory / Consultancy, Research grant / Funding (institution): Seattle Genetics; Advisory / Consultancy, Research grant / Funding (institution): Genentech/Roche; Advisory / Consultancy: AstraZeneca; Advisory / Consultancy, Leadership role, Research grant / Funding (institution): OncoMed; Advisory / Consultancy: Celgene; Advisory / Consultancy: Proteus Digital Health; Advisory / Consultancy: Chengdu Kanghong Biotechnology Co., Ltd; Research grant / Funding (institution): Exelixis; Research grant / Funding (institution): Sanofi; Research grant / Funding (institution): Nektar; Research grant / Funding (institution): Abbvie; Research grant / Funding (institution): Gilead Sciences; Research grant / Funding (institution): Macrogenics; Research grant / Funding (institution): Leap Therapeutics; Research grant / Funding (institution): MedImmune. All other authors have declared no conflicts of interest.