AXL is a predictor of poor survival and of resistance to anti-EGFR therapy in RAS wild-type metastatic colorectal cancer

Claudia Cardone, Bernadette Blauensteiner, Veronica Moreno-Viedma, Giulia Martini, Vittorio Simeon, Pietro P. Vitiello, Davide Ciardiello, Valentina Belli, Nunzia Matrone, Teresa Troiani, Floriana Morgillo, Federica Zito Marino, Monica Dentice, Annarita Nappi, Alessandra Boccaccino, Carlotta Antoniotti, Chiara Cremolini, Filippo Pietrantonio, Gerald W. Prager, Nicola NormannoEvaristo Maiello, Guillem Argiles, Elena Elez, Giuseppe Signoriello, Renato Franco, Alfredo Falcone, Josep Tabernero, Maria Sibilia, Fortunato Ciardiello, Erika Martinelli

Research output: Contribution to journalArticlepeer-review


Background: RAS mutations are the only validated biomarkers in metastatic colorectal cancer (mCRC) for anti-epidermal growth factor receptor (EGFR) therapy. Limited clinical information is available on AXL expression, marker of epithelial to mesenchymal transition, in mCRC. Methods: AXL was retrospectively assessed by immunohistochemistry in 307 patients. RAS wild-type (WT) patients (N = 136) received first-line anti-EGFR–based therapy; RAS mutant patients (N = 171) received anti-angiogenic–based regimens. Preclinical experiments were performed using human RAS WT CRC cell lines and xenograft models. AXL RNA levels were assessed in a cohort of patients with available samples at baseline and at progression to anti-EGFR treatment and in the GSE5851 dataset. Results: AXL was expressed in 55/307 tumour tissues, correlating with worse survival in the overall population (AXL-positive, 23.7 months; AXL-negative, 30.8 months; HR, 1.455, P = 0.032) and in RAS WT patients (AXL-positive, 23.0 months; AXL-negative, 35.8 months; HR,1.780, P = 0.032). Progression-free survival (PFS) in the RAS WT cohort was shorter in the AXL-positive cohort (6.2 months versus 12.1 months; HR, 1.796, P = 0.013). Three-dimensional cultures obtained from a patient following anti-EGFR therapy resulted AXL-positive, showing resistance to anti-EGFR drugs and sensitivity to AXL inhibition. AXL transfection in CRC cell lines induced AXL overexpression and resistance to the EGFR blockade. At progression to cetuximab, 2/10 SW48-tumour xenograft mice showed AXL expression. Consistently, AXL RNA levels increased in 5/7 patients following anti-EGFR therapy. Moreover, in the GSE5851 dataset higher AXL RNA levels correlated with worse PFS with cetuximab in KRAS-exon2 WT chemorefractory patients. Conclusions: AXL is a marker of poor prognosis in mCRC with consistent clinical and preclinical evidences of involvement in primary and acquired resistance to anti-EGFR drugs in RAS WT patients.

Original languageEnglish
Pages (from-to)1-10
Number of pages10
JournalEuropean Journal of Cancer
Publication statusPublished - Oct 2020


  • AXL
  • Colorectal cancer
  • EGFR resistance
  • RAS WT

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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