A module of inflammatory cytokines defines resistance of colorectal cancer to EGFR inhibitors

Epidermal Growth Factor Receptor (EGFR) activates a robust signalling network to which colon cancer tumours often become addicted. Cetuximab, one of the monoclonal antibodies targeting this pathway, is employed to treat patients with colorectal cancer. However, many patients are intrinsically refractory to this treatment, and those who respond develop secondary resistance along time. Mechanisms of cancer cell resistance include either acquisition of new mutations or non genomic activation of alternative signalling routes. In this study, we employed a colon cancer model to assess potential mechanisms driving resistance to cetuximab. Resistant cells displayed increased ability to grow in suspension as colonspheres and this phenotype was associated with poorly organized structures. Factors secreted from resistant cells were causally involved in sustaining resistance, indeed administration to parental cells of conditioned medium collected from resistant cells was sufficient to reduce cetuximab efficacy. Among secreted factors, we report herein that a signature of inflammatory cytokines, including IL1A, IL1B and IL8, which are produced following EGFR pathway activation, was associated with the acquisition of an unresponsive phenotype to cetuximab in vitro. This signature correlated with lack of response to EGFR targeting also in patient-derived tumour xenografts. Collectively, these results highlight the contribution of inflammatory cytokines to reduced sensitivity to EGFR blockade and suggest that inhibition of this panel of cytokines in combination with cetuximab might yield an effective treatment strategy for CRC patients refractory to anti-EGFR targeting

AhR controls redox homeostasis and shapes the tumor microenvironment in BRCA1-associated breast cancer

Cancer cells have higher reactive oxygen species (ROS) than normal cells, due to genetic and metabolic alterations. An emerging scenario is that cancer cells increase ROS to activate protumorigenic signaling while activating antioxidant pathways to maintain redox homeostasis. Here we show that, in basal-like and BRCA1-related breast cancer (BC), ROS levels correlate with the expression and activity of the transcription factor aryl hydrocarbon receptor (AhR). Mechanistically, ROS triggers AhR nuclear accumulation and activation to promote the transcription of both antioxidant enzymes and the epidermal growth factor receptor (EGFR) ligand, amphiregulin (AREG). In a mouse model of BRCA1-related BC, cancer-associated AhR and AREG control tumor growth and production of chemokines to attract monocytes and activate proangiogenic function of macrophages in the tumor microenvironment. Interestingly, the expression of these chemokines as well as infiltration of monocyte-lineage cells (monocyte and macrophages) positively correlated with ROS levels in basal-like BC. These data support the existence of a coordinated link between cancer-intrinsic ROS regulation and the features of tumor microenvironment. Therapeutically, chemical inhibition of AhR activity sensitizes human BC models to Erlotinib, a selective EGFR tyrosine kinase inhibitor, suggesting a promising combinatorial anticancer effect of AhR and EGFR pathway inhibition. Thus, AhR represents an attractive target to inhibit redox homeostasis and modulate the tumor promoting microenvironment of basal-like and BRCA1-associated BC

Tailored cancer immunotherapy using combinations of chemotherapy and a mixture of antibodies against EGF-receptor ligands

Growth factors are implicated in several processes essential for cancer progression. Specifically, growth factors that bind to ErbB family receptors have been implicated in cell proliferation and in resistance of solid tumors to chemotherapy. We quantified ligand secretion by several human cancer cell lines, and generated mAbs against two ligands, namely TGF-α and heparin-binding EGF-like growth factor. These growth factors are frequently secreted by pancreatic tumor cell lines, including BxPC3 cells. The monoclonal antibodies were tested for their antigen specificity and ability to inhibit growth of BxPC3 cells in vitro. Combining the two antibodies resulted in enhanced inhibition of BxPC3 cell growth, both in vitro and in tumor-bearing animals. Hence, we combined the two antibodies with gemcitabine, an effective chemotherapeutic drug commonly used to treat pancreatic cancer patients. Because treatment with a combination of two monoclonal antibodies enhanced the ability of chemotherapy to inhibit BxPC3 tumors in mice, we propose a general cancer therapeutic strategy that entails profiling the repertoire of growth factors secreted by a tumor, and combining with chemotherapy several antibodies capable of blocking autocrine ligands

Molecular mechanisms of resistance to cetuximab mediated by IL-1 signaling

Cetuximab (CTX) is a monoclonal antibody targeting Epidermal Growth Factor Receptor (EGFR), which is commonly employed to treat patients with metastatic colorectal cancer (mCRC). Unfortunately, clinicians often observe a failure of the therapy with a population of cells surviving the treatment and eventually enabling CTX resistance. Our previous studies, employing a cohort of 150 CRC xenopatients, associated poor response to CTX with increase abundance of a set of inflammatory cytokines, namely IL-1, IL-1 and IL-8 (Gelfo et al., 2016). In the time frame of my first year of Ph.D, we found that in patients, undergoing CTX treatment, overexpression of IL-1 Receptor (IL-1R) correlates with reduced response. Stemming from these observations, we assumed that resistance to CTX is acquired, in a subset of CRC patients, through cell plasticity, as a consequent rewiring of signaling networks. Employing a recombinant decoy (IL1R-Fc) able to sequester IL-1 directly from the medium, our results show that IL1R decoy successfully dampens pSTAT3 activation along with MAPK and PI3K axes, thus decreasing proliferation and colon spheres formation. Furthermore, we report that IL1R abundance predicts disease relapse free survival in a cohort of 1700 colorectal cancer patients, and it appears associated to a specific subtype, namely the consensus molecular subtype 1 (CMS1). Our data therefore suggest that a loop mediated by the IL1 and its cognate receptor mediates CTX resistance in a specific subtype of colorectal cancer. Mechanistically, our preliminary data show that CTX treatment promotes an increase in inflammatory cytokines leading to a post-senescent phenotype, as detected by -galactosidase, HP1- and p21 markers

A putative role for interleukin 1 pathway in resistance to EGFR blockade

Cetuximab (CX) is a monoclonal antibody targeting the Epidermal Growth Factor Receptor (EGFR), which is commonly utilized to treat patients with metastatic colorectal cancer (mCRC). Unfortunately, clinicians often observe a residual disease, with a population of cells surviving the treatment and eventually enabling CX resistance. Our previous studies, performed with a cohort of 150 CRC xenopatients, associated poor response to CX with increased abundance of a set of inflammatory cytokines, including IL1A, B and IL8. Stemming from these observations, our working hypothesis assumes that, resistance to CX is acquired, in a subset of CRC patients, through cell plasticity and consequent rewiring of signalling networks, which confer to tumors dependency on the IL1 pathway. In order to assess the effect of IL1 activity, we employed a colon cancer model unresponsive to cetuximab, as previously characterized in our laboratory. To inhibit activation of the IL1 pathway we used anakinra, an IL1-receptor antagonist and parthenolide, which modulates the activity of NF-kB, the transcription factor involved in the feed-forward loop of inflammation mediators. Furthermore, we employed a recombinant decoy (IL1R-Fc), namely a soluble protein combining the human immunoglobulin Fc portion linked to the extracellular region of IL1-receptor, with the ability to sequester IL1 directly from the medium. We generated stable clones of CXresistant cells expressing IL1R-Fc. Our preliminary results show that inhibition of IL1R leads to a proliferation decrease of colorectal cancer cells. These findings support the hypothesis of a compensatory activation of the IL1-receptor pathway in cetuximab-resistant CRC cells. Hence, modulating IL1 signalling might represent a new therapeutic strategy suitable for patients who acquired refractoriness to monoclonal antibody therapy

A Novel Role for the Interleukin-1 Receptor Axis in Resistance to Anti-EGFR Therapy

Cetuximab (CTX) is a monoclonal antibody targeting the epidermal growth factor receptor (EGFR), commonly used to treat patients with metastatic colorectal cancer (mCRC). Unfortunately, objective remissions occur only in a minority of patients and are of short duration, with a population of cells surviving the treatment and eventually enabling CTX resistance. Our previous study on CRC xenopatients associated poor response to CTX with increased abundance of a set of pro-inflammatory cytokines, including the interleukins IL-1A, IL-1B and IL-8. Stemming from these observations, our current work aimed to assess the role of IL-1 pathway activity in CTX resistance. We employed a recombinant decoy TRAP IL-1, a soluble protein combining the human immunoglobulin Fc portion linked to the extracellular region of the IL-1-receptor (IL-1R1), able to sequester IL-1 directly from the medium. We generated stable clones expressing and secreting a functional TRAP IL-1 into the culture medium. Our results show that IL-1R1 inhibition leads to a decreased cell proliferation and a dampened MAPK and AKT axes. Moreover, CRC patients not responding to CTX blockage displayed higher levels of IL-1R1 than responsive subjects, and abundant IL-1R1 is predictive of survival in patient datasets specifically for the consensus molecular subtype 1 (CMS1). We conclude that IL-1R1 abundance may represent a therapeutic marker for patients who become refractory to monoclonal antibody therapy, while inhibition of IL-1R1 by TRAP IL-1 may offer a novel therapeutic strategy

Mechanisms of acquired resistance to cetuximab: role of interleukin-1

Cetuximab (CX) is a monoclonal antibody targeting the Epidermal Growth Factor Receptor (EGFR), which is commonly utilized to treat patients with metastatic colorectal cancer (mCRC). Unfortunately, clinicians often observe a residual disease, with a population of cells surviving the treatment and eventually enabling CX resistance. Our previous studies, performed with a cohort of 150 CRC xenopatients, associated poor response to CX with increased abundance of a set of inflammatory cytokines, including IL1A, B and IL8. Stemming from these observations, our working hypothesis assumes that, resistance to CX is acquired, in a subset of CRC patients, through cell plasticity and consequent rewiring of signalling networks, which confer to tumors dependency on the IL1 pathway. In order to assess the effect of IL1 activity, we employed a colon cancer model unresponsive to cetuximab, as previously characterized in our laboratory. To inhibit activation of the IL1 pathway we used anakinra, an IL1-receptor antagonist and parthenolide, which modulates the activity of NF-kB, the transcription factor involved in the feed-forward loop of inflammation mediators. Furthermore, we employed a recombinant decoy (IL1R-Fc), namely a soluble protein combining the human immunoglobulin Fc portion linked to the extracellular region of IL1-receptor, with the ability to sequester IL1 directly from the medium. We generated stable clones of CX-resistant cells expressing IL1R-Fc. Our preliminary results show that inhibition of IL1R leads to a proliferation decrease of colorectal cancer cells. These findings support the hypothesis of a compensatory activation of the IL1-receptor pathway in cetuximab-resistant CRC cells. Hence, modulating IL1 signalling might represent a new therapeutic strategy suitable for patients who acquired refractoriness to monoclonal antibody therapy