Proof-of-concept pilot study on comprehensive spatiotemporal intra-patient heterogeneity for colorectal cancer with liver metastasis

Abstract

Purpose: The mechanisms underlying high drug resistance and relapse rates after multi-modal treatment in patients with colorectal cancer (CRC) and liver metastasis (LM) remain poorly understood. We evaluate the potential translational implications of intra-patient heterogeneity (IPH) comprising primary and matched metastatic intratumor heterogeneity (ITH) coupled with circulating tumor DNA (ctDNA) variability. Patients and methods: According to our IPH-based protocol, 18 eligible patients with CRC-LM, who underwent complete tumor resection after neo-adjuvant treatment, with a total of 122 multi-regional tumor and perioperative liquid biopsies were analyzed via next-generation sequencing (NGS) of a custom 77-gene panel. The primary endpoints were the extent of IPH and the frequency of actionable mutations. Results: The proportion of patients with ITH were 53% and 56% in primary CRC and LM respectively, while 35% of patients harbored de novo mutations in LM indicating spatiotemporal tumor evolution and the necessity of multiregional analysis. Among the 56% of patients with alterations in liquid biopsies, de novo mutations in cfDNA were identified in 25% of patients, which were undetectable in both CRC and LM. All 17 patients with driver alterations harbored actionable mutations, with an average of 3.2 oncogenic events per patient, for molecularly targeted drugs either approved or under evaluation in ongoing clinical trials or in pre-clinical studies. Conclusions: Our proof-of-concept prospective study provides initial evidence and warrants the conduction of precision oncology trials to test the potential clinical utility of IPH-driven matched therapy.