Circulating Tumor DNA (ctDNA) Dynamics and Clinical Outcome in Metastatic Colorectal Cancer (mCRC) Patients (pts) Undergoing Front-line Chemotherapy - M. Ghidini; J. Claus Hahne; C. Senti; G. Tomasello; M. Ratti; T. Heide; O. Garrone; A. Cortellini; R. Passalacqua; N. Valeri (The Journal of Liquid Biopsy)