Research ArticleCancer

Colorectal cancer residual disease at maximal response to EGFR blockade displays a druggable Paneth cell–like phenotype

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Science Translational Medicine  05 Aug 2020:
Vol. 12, Issue 555, eaax8313
DOI: 10.1126/scitranslmed.aax8313

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Tumor cells hunker down to escape

Targeted therapy inhibiting pathways involved in tumor growth is becoming increasingly common. This includes inhibitors of the epidermal growth factor receptor, which are used for a variety of tumor types including colorectal cancer. Unfortunately, the treatment’s effects are often incomplete such that residual cancer cells stay behind and contribute to relapse. Lupo et al. examined these residual cancer cells, which proliferate relatively slowly, and identified their similarities to a subtype of normal intestinal cells. The authors examined the signaling pathways active in these cells and identified potential interventions that worked in multiple patient-derived xenografts, suggesting that they may translate to patients.

Abstract

Blockade of epidermal growth factor receptor (EGFR) causes tumor regression in some patients with metastatic colorectal cancer (mCRC). However, residual disease reservoirs typically remain even after maximal response to therapy, leading to relapse. Using patient-derived xenografts (PDXs), we observed that mCRC cells surviving EGFR inhibition exhibited gene expression patterns similar to those of a quiescent subpopulation of normal intestinal secretory precursors with Paneth cell characteristics. Compared with untreated tumors, these pseudodifferentiated tumor remnants had reduced expression of genes encoding EGFR-activating ligands, enhanced activity of human epidermal growth factor receptor 2 (HER2) and HER3, and persistent signaling along the phosphatidylinositol 3-kinase (PI3K) pathway. Clinically, properties of residual disease cells from the PDX models were detected in lingering tumors of responsive patients and in tumors of individuals who had experienced early recurrence. Mechanistically, residual tumor reprogramming after EGFR neutralization was mediated by inactivation of Yes-associated protein (YAP), a master regulator of intestinal epithelium recovery from injury. In preclinical trials, Pan-HER antibodies minimized residual disease, blunted PI3K signaling, and induced long-term tumor control after treatment discontinuation. We found that tolerance to EGFR inhibition is characterized by inactivation of an intrinsic lineage program that drives both regenerative signaling during intestinal repair and EGFR-dependent tumorigenesis. Thus, our results shed light on CRC lineage plasticity as an adaptive escape mechanism from EGFR-targeted therapy and suggest opportunities to preemptively target residual disease.

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