EGFR Expression Is Unreliable to Decide for Cetuximab Treatment in Patients with Metastatic Colorectal Cancer: Results from “ERBITUX-OUEST”

Purpose: Although controversial, assessment of epidermal growth factor receptor (EGFR) expression is required for the approved indications of Cetuximab in metastatic colorectal cancer (mCRC). With the objective of improving patient selection, “ERBITUX-OUEST” study aimed at analyzing EGFR status in a large cohort of mCRC patients who received cetuximab without preliminary EGFR screening, and assessing the correlation between EGFR status and response to treatment retrospectively. Patients and methods: 332 patients treated with Irinotecan Cetuximab based regimen after progression on irinotecan or oxaliplatin therapy were included. EGFR status was assessed using three available immunohistochemistry (IHC) tests and in situ hybridization in case of negativity. Clinical outcomes of EGFR-positive and EGFR-non-detected (or considered as negative with at least one test) patients were compared. Results: Of the 332 samples centrally screened, 194 were classified as full-positive (i.e., EGFR-positive for all three tests), 86 as full-negative, and 52 as discordant. One third of the 131 negative samples with FDA approved test should be reclassified as positive with at least one of the two others tests. Regarding results from FDA approved test only, neither objective response rate (ORR), progression-free survival (PFS) nor overall survival (OS) differed significantly between EGFR-negative and EGFR-positive patients (P = 0.788, 0.326 and 0.888, respectively). Similarly, comparison of full-negative to other groups did not show any significant difference in terms of ORR (P = 0.507), PFS (P = 0.222) or OS (P = 0.686). Conclusion: These data strongly argue against mCRC patients selection for Cetuximab treatment based on EGFR expression as measured by currently available IHC technics.

Sorafenib Acts through VEGFR-2 Inhibition in a Metastatic Clear-Cell Sarcoma of the Kidney

We report here the case of a young patient with metastatic clear-cell sarcoma of the kidney resistant to standard chemotherapy, and with complete response under sorafenib treatment. The remarkable response of her tumor to sorafenib led us to study sorafenib molecular targets in the metastatic tissue. Background: Biomarkers predicting response to anti-angiogenic tyrosine kinase inhibitors remain to be identified. Methods and Findings: In this paper, we studied the molecular targets of sorafenib in the lung metastasis of a kidney clear-cell sarcoma. In a patient with complete response under sorafenib treatment, we showed high VEGFR2 expression by tumor endothelial cells from the lung metastasis. Conclusion: The original mechanistic results that we obtained using immunostainings and quantitative RT-PCR on laser-microdissected tumor endothelial cells have a direct application in daily clinical practice: metastatic tumors with a large angiogenic component should be tested for VEGFRs expression to consider anti-angiogenic tyrosine kinase inhibitor treatments.

RIP140 regulates POLK gene expression and the response to alkylating drugs in colon cancer cells

Aim:The transcription factor RIP140(receptor interacting protein of 140 kDa)is involved in intestinal tumorigenesis.It plays a role in the control of microsatellite instability(MSI),through the regulation of MSH2 and MSH6 gene expression.The aim of this study was to explore its effect on the expression of POLK,the gene encoding the specialized translesion synthesis(TLS)DNA polymeraseκknown to perform accurate DNA synthesis at microsatellites.Methods:Different mouse models and engineered human colorectal cancer(CRC)cell lines were used to analyze by RT-qPCR,while Western blotting and luciferase assays were used to elucidate the role of RIP140 on POLK gene expression.Published DNA microarray datasets were reanalyzed.The in vitro sensitivity of CRC cells to methyl methane sulfonate and cisplatin was determined.Results:RIP140 positively regulates,at the transcriptional level,the expression of the POLK gene,and this effect involves,at least partly,the p53 tumor suppressor.In different cohorts of CRC biopsies(with or without MSI),a strong positive correlation was observed between RIP140 and POLK gene expression.In connection with its effect on POLK levels and the TLS function of this polymerase,the cellular response to methyl methane sulfonate was increased in cells lacking the Rip140 gene.Finally,the association of RIP140 expression with better overall survival of CRC patients was observed only when the corresponding tumors exhibited low levels of POLK,thus strengthening the functional link between the two genes in human CRC.Conclusion:The regulation of POLK gene expression by RIP140 could thus contribute to the maintenance of microsatellite stability,and more generally to the control of genome integrity.