Cetuximab in combination therapy: from bench to clinic

EGFR-Targeted Antibody-Drug Conjugate to Different Aminobisphosphonates: Direct and Indirect Antitumor Effects on Colorectal Carcinoma Cells

Antibody--drug conjugates (ADCs) are a promising delivery system that involves linking a monoclonal antibody (mAb) to a specific drug, such as a cytotoxic agent, to target tumor cells. This new class of antitumor therapy acts as a "biological missile" that can destroy tumor cells while increasing the therapeutic index and decreasing toxicity. One of the most critical factors in ADC design is selecting a target antigen that is highly expressed on the surface of cancer cells. In this study, we conjugated Cetuximab (Cet), a monoclonal antibody that targets the epidermal growth factor receptor (EGFR), to aminobisphosphonates (N-BPs) such as ibandronate (IBA) or risedronate (RIS) or zoledronate (ZA). Cetuximab is administered to patients with metastatic colorectal carcinoma (mCRC) with a wild-type (WT) EGFR transduction pathway. Also, it is well established that N-BPs can trigger the antitumor activity of Vδ2 T cells in both in vitro and in vivo experimental models. The resulting ADCs were added in co-culture to assess the effect on CRC cell line proliferation and sensitivity to Vδ2 T antitumor lymphocytes in comparison with the native antibody. These assays have been performed both in conventional and 3D spheroid cultures. We found that all three ADCs can increase the inhibitory effect on cell proliferation of the WT-EGFR cell line Caco-2 while only Cet-RIS and Cet-ZA can increase the cytotoxicity mediated by Vδ2 T cells against both WT and EGFR-mutated CRC cell lines (Caco-2, DLD-1, and HCT-116). Also, the ADCs can trigger the cell proliferation of Vδ2 T cells present in peripheral blood and tumor specimens. Our findings indicate that anti-EGFR antibodies bound to N-BPs can improve the antitumor effects of the native antibody possibly increasing the therapeutic effect.

Antibody-platinum (IV) prodrugs conjugates for targeted treatment of cutaneous squamous cell carcinoma

Antibody-drug conjugates (ADCs) are a new type of targeting antibodies that conjugate with highly toxic anticancer drugs via chemical linkers to exert high specificity and efficient killing of tumor cells, thereby attracting considerable attention in precise oncology therapy. Cetuximab (Cet) is a typical antibody that offers the benefits of good targeting and safety for individuals with advanced and inoperable cutaneous squamous cell carcinoma (cSCC); however, its anti-tumor activity is limited to a single use. Cisplatin (CisPt) shows good curative effects; however, its adverse effects and non-tumor-targeting ability are major drawbacks. In this study, we designed and developed a new ADC based on a new cytotoxic platinum (IV) prodrug (C8Pt(IV)) and Cet. The so-called antibody-platinum (IV) prodrugs conjugates, named Cet-C8Pt(IV), showed excellent tumor targeting in cSCC. Specifically, it accurately delivered C8Pt(IV) into tumor cells to exert the combined anti-tumor effect of Cet and CisPt. Herein, metabolomic analysis showed that Cet-C8Pt(IV) promoted cellular apoptosis and increased DNA damage in cSCC cells by affecting the vitamin B6 metabolic pathway in tumor cells, thereby further enhancing the tumor-killing ability and providing a new strategy for clinical cancer treatment using antibody-platinum (IV) prodrugs conjugates.

Monoclonal Antibodies: A Prospective and Retrospective View

BACKGROUND

Monoclonal Antibodies (mAbs) represent one of the most important classes of biotherapeutic agents. They are used to cure many diseases, including cancer, autoimmune diseases, cardiovascular diseases, angiogenesis-related diseases and, more recently also haemophilia. They can be highly varied in terms of format, source, and specificity to improve efficacy and to obtain more targeted applications. This can be achieved by leaving substantially unchanged the basic structural components for paratope clustering.

OBJECTIVES

The objective was to trace the most relevant findings that have deserved prestigious awards over the years, to report the most important clinical applications and to emphasize their latest emerging therapeutic trends.

RESULTS

We report the most relevant milestones and new technologies adopted for antibody development. Recent efforts in generating new engineered antibody-based formats are briefly reviewed. The most important antibody-based molecules that are (or are going to be) used for pharmacological practice have been collected in useful tables.

CONCLUSION

The topics here discussed prove the undisputed role of mAbs as innovative biopharmaceuticals molecules and as vital components of targeted pharmacological therapies.

Comparative efficacy and safety of radiotherapy/cetuximab versus radiotherapy/chemotherapy for locally advanced head and neck squamous cell carcinoma patients: a systematic review of published, primarily non-randomized, data

Background:

Cetuximab (CTX) has been approved to be administered concurrently with radiotherapy (RT) to treat locally advanced head and neck squamous cell carcinoma (HNSCC). The aim of this study was to assess the efficacy and safety of concurrent CTX with RT (ExRT).

Method:

The PubMed, Cochrane Library, EMBASE databases were systematically searched to find relevant articles. The combined hazard ratio (HR), risk ratio (RR) and 95% confidence interval were calculated to assess the efficacy and safety of ExRT in contrast to concurrent platinum-based chemotherapy with RT (ChRT).

Results:

In total, 32 articles with 4556 patients were included. The pooled HRs indicated that ExRT achieved an unfavorable overall survival (HR: 1.86, p < 0.0001), disease-specific survival (HR: 2.58, p = 0.002), locoregional control (HR: 1.94, p < 0.00001), and progression-free survival (HR: 2.04, p = 0.003) compared with ChRT for locally advanced HNSCC patients. In human papillomavirus-positive patient subgroups, ExRT showed inferior disease-specific survival (HR: 2.55, p = 0.009) and locoregional control (HR: 2.27, p < 0.0001) in contrast to ChRT. Additionally, ExRT increased the occurrence of mucositis (RR: 1.17, p < 0.005), skin toxicity (RR: 6.26, p < 0.00001), and infection (RR: 2.27, p = 0.04) compared with non-CTX groups (ChRT and RT), and was associated with lower incidence of anemia (RR: 0.35, p = 0.009), leukocytopenia (RR: 0.17, p < 0.0001), neutropenia (RR: 0.06, p < 0.0001), nausea/vomiting (RR: 0.23, p < 0.0001), and renal toxicity (RR: 0.14, p = 0.007).

Conclusion:

ChRT should remain the standard treatment for locally advanced HNSCC patients. ExRT was recognized as an effective alternative treatment for locally advanced HNSCC patients who experienced unbearable toxicities caused by non-CTX treatments.

The functional verification of EGFR-CAR T-cells targeted to hypopharyngeal squamous cell carcinoma

BACKGROUND

The aim of this study was to validate the antitumor function of EGFR-chimeric antigen T-cells (CART) targeted to FaDu cells, a hypopharyngeal squamous cell carcinoma cell line, and to provide a preclinical basis for the application of CART cell technology in hypopharyngeal squamous cell carcinoma.

METHODS

Detection of cytokine secretions of EGFR-CAR T and CART-controls in the presence of target cells and nontarget cells as an indicator of CART cell activation. Detection of the cytotoxic effects of EGFR-CAR T on specific tumors in the presence of target cells was evaluated by LDH release and CART cell proliferation.

RESULTS

The results showed that cytokine secretion increased significantly after EGFR-CAR T-cells were incubated with target cells, and EGFR-CAR T-cells has higher cytotoxic effect on target cells than the CART-control group. The target cell lysis rate was 52.66%. The proliferation of EGFR-CAR T-cells in the presence of target cells was not distinctly observed.

CONCLUSION

In this study, we validated the antitumor function of EGFR-CAR T-cells targeted to the FaDu cell line and provided the foundation for application of the CART technique in the treatment of hypopharyngeal carcinoma.

The relevance of ADCC for EGFR targeting: A review of the literature and a clinically-applicable method of assessment in patients

BACKGROUND

Advances in the understanding of tumor biology have led to the development of targeted therapies as monoclonal antibodies (MoAbs) in clinical oncology. Among their suggested mechanisms of action monoclonal antibodies (IgG1) selectively directed against tumor membrane receptors mediate of antibody-dependent cellular cytotoxicity (ADCC) by triggering Fc-γRIII on natural killer (NK) cells.

METHODS

This study reviews the clinical context of ADCC measurement with a particular focus on EGFR targeting and describes an ex vivo ADCC method applied to MoAbs (cetuximab and panitumumab), against epidermal growth factor receptor (EGFR). The test performance was evaluated on different target cells lines (CAL166, A431, HNO91, CAL27), with different effector cells (peripheral blood mononuclear cells or natural killers -NK-) and in various experimental conditions, in order to establish a truly clinically applicable method.

RESULTS

Using the experience available in the published literature, we optimized all variables involved in the experimental design: target cells type, numbers and ratio target cells and NK cells (effector cells) per well, time of exposure and repeatability.

CONCLUSION

ADCC measurement may be of clinical relevance in the context of treatment with MoAbs. This study describes a non-radioactive method which has proven satisfactory in terms of sensitivity, reproducibility, feasibility and cost effectiveness for the measurement of ADCC activity mediated by NK with an orientation towards the EGFR target.

Twist1 induces endothelial differentiation of tumour cells through the Jagged1-KLF4 axis

The mechanisms controlling tumour-induced angiogenesis are presently not clear. In principle, angiogenesis can be achieved through the activation of endothelial cells in existing vessels or by transdifferentiation of tumour cells into endothelial cells. However, whether tumour cells can go through a prior epithelial-mesenchymal transition and further differentiate into endothelial cells remains unknown. Here we show that overexpression of Twist1, a transcriptional regulator that induces and promotes cancer metastasis, leads to endothelial differentiation in head and neck cancer (HNC) cells. Induction of Jagged1 expression by Twist1 is essential for Twist1-induced endothelial differentiation. The Jagged1/Notch signalling subsequently activates KLF4, inducing stem-like properties in HNC cells and conferring them with drug resistance. Our results indicate that the Twist1-Jagged1/KLF4 axis is essential both for transdifferentiation of tumour cells into endothelial cells and for chemoresistance acquisition.

Acquired resistance to cetuximab is associated with the overexpression of Ras family members and the loss of radiosensitization in head and neck cancer cells

PURPOSE

Cetuximab in combination with radiation therapy is used to treat patients with head and neck squamous cell carcinoma (HNSCC). In the present study, the mechanism of acquired resistance to cetuximab in HNSCC cells was investigated in vitro.

MATERIAL AND METHODS

The HNSCC cell lines UT5 and SAS and UT5 cells with acquired resistance to cetuximab (UT5R9) were used. The radiotoxicity potentials of cetuximab and inhibitors of PI3K, MAPK and farnesylation were tested using a clonogenic survival assay. Western blotting was used to evaluate protein expression. The levels of EGFR ligands were detected by ELISA.

RESULTS

Cetuximab inhibited proliferation and induced radiosensitization in UT5 cells but not in SAS cells. In comparison with UT5 cells, cetuximab-resistant SAS cells markedly overexpressed the K-Ras, H-Ras and N-Ras proteins, as detected by Western blotting. Resistance in UT5R9 cells was associated with the overexpression of the K-Ras, H-Ras and N-Ras proteins as well as an increase in the autocrine production of the EGFR ligands amphiregulin and transforming growth factor α (TGFα). UT5R9 cells were significantly more radioresistant than UT5 cells. Radioresistant UT5R9 cells were not radiosensitized by cetuximab, but knocking down H-RAS and N-RAS with siRNA and targeting Ras farnesylation using the farnesyltransferase inhibitor lonafarnib induced radiosensitization in these cells. Targeting PI3K and MEK revealed that the activation of the PI3K/Akt pathway but not the MAPK/ERK pathway is associated with radioresistance in UT5R9 cells.

CONCLUSION

Targeting Ras and PI3K activity improves the outcome of irradiation in cetuximab-resistant HNSCC cell lines in vitro.

Evaluation of EGFR-targeted radioimmuno-gold-nanoparticles as a theranostic agent in a tumor animal model

This study evaluated the tumor targeting and therapeutic efficacy of a novel theranostic agent (131)I-labeled immuno-gold-nanoparticle ((131)I-C225-AuNPs-PEG) for high epidermal growth factor receptor (EGFR)-expressed A549 human lung cancer. Confocal microscopy demonstrated the specific uptake of C225-AuNPs-PEG in A549 cells. (131)I-C225-AuNPs-PEG induced a significant reduction in cell viability, which was not observed when incubated with AuNPs-PEG and C225-AuNPs-PEG. MicroSPECT/CT imaging of tumor-bearing mice after intravenous injection of (123)I-C225-AuNPs-PEG revealed significant radioactivity retention in tumor suggested that (131)I-labeled C225-conjugated radioimmuno-gold-nanoparticles may provide a new approach of targeted imaging and therapy towards high EGFR-expressed cancers.

Cetuximab in combination with anti-human IgG antibodies efficiently down-regulates the EGF receptor by macropinocytosis

The monoclonal antibody C225 (Cetuximab) blocks binding of ligand to the epidermal growth factor receptor (EGFR). In addition, it is known that incubation with C225 induces endocytosis of the EGFR. This endocytosis has previously been shown to be increased when C225 is combined with an additional monoclonal anti-EGFR antibody. However, the effects of antibody combinations on EGFR activation, endocytosis, trafficking and degradation have been unclear. By binding a secondary antibody to the C225-EGFR complex, we here demonstrate that a combination of antibodies can efficiently internalize and degrade the EGFR. Although the combination of antibodies activated the EGFR kinase and induced ubiquitination of the EGFR, the kinase activity was not required for internalization of the EGFR. In contrast to EGF-induced EGFR down-regulation, the antibody combination efficiently degraded the EGFR without initiating downstream proliferative signaling. The antibody-induced internalization of EGFR was found not to depend on clathrin and/or dynamin, but depended on actin polymerization, suggesting induction of macropinocytosis. Macropinocytosis may cause internalization of large membrane areas, and this could explain the highly efficient internalization of the EGFR induced by combination of antibodies.

Phosphatase and tensin homolog expression related to cetuximab effects in colorectal cancer patients: A meta-analysis

AIM: To investigate the correlation between expression of phosphatase and tensin homolog (PTEN) and cetuximab effects in colorectal cancer.

METHODS: We searched PubMed, EMBASE and ASCO to identify eligible studies. Finally, 8 randomized control studies were included in the meta-analysis. STATA 10.0 Software was used to investigate heterogeneity among individual studies and to summarize all the studies. Risk ratios (RRs) and hazard ratios (HRs) with 95% confidence intervals (CIs) were used to assess the strength of the association.

RESULTS: Compared with 20 of 266 patients with loss of PTEN, 206 of 496 patients with intact PTEN protein expression had a better objective response rate to cetuximab-based therapy (RR, 4.75; 95% CI, 2.59-8.72; P < 0.001). PTEN positivity was associated with better progression-free survival (PFS) (HR, 0.675; 95% CI, 0.473-0.964; P = 0.031) but not with better overall survival (OS) (HR, 0.608; 95% CI, 0.411-0.899; P = 0.013). In patients with KRAS wild-type status, PTEN positivity did not predict a longer PFS or OS (PFS: HR, 0.707; 95% CI, 0.440-1.138; P = 0.154; OS: HR, 0.943; 95% CI, 0.646-1.377; P = 0.761).

CONCLUSION: Expression of PTEN is related to the effect of cetuximab in colorectal cancer patients and should be considered in treatment with cetuximab.

Human glioblastoma stem-like cells are more sensitive to allogeneic NK and T cell-mediated killing compared with serum-cultured glioblastoma cells

Glioblastoma multiforme (GBM) is the most dramatic primary brain cancer with a very poor prognosis because of inevitable disease recurrence. The median overall survival is less than 1 year after diagnosis. Cancer stem cells have recently been disclosed in GBM. GBM stem-like cells (GSCs) exhibit resistance to radio/chemotherapeutic treatments and are therefore considered to play an important role in disease recurrence. GSCs are thus appealing targets for new treatments for GBM patients. In this study, we show that GBM cells with stem cell characteristics are resistant to lysis mediated by resting natural killer (NK) cells because of the expression of MHC class I molecules. However, GSCs are killed by lectin-activated NK cells. Furthermore, in experiments using the therapeutic antibody CetuximAb, we show that GSCs are sensitive to antibody-mediated cytotoxicity. We confirm the sensitivity of GSC to cytotoxicity carried out by IL2-activated NK cells and tumor-specific T cells. More importantly, we show that GSCs are more sensitive to NK and T cell-mediated lysis relatively to their corresponding serum-cultured GBM cells obtained from the same initial tumor specimen. Altogether, these results demonstrate the sensitivity of GSC to immune cell cytotoxicity and, therefore, strongly suggest that GSCs are suitable target cells for immunotherapy of GBM patients.

Comparison of the effects of carbon ion and photon irradiation on the angiogenic response in human lung adenocarcinoma cells

PURPOSE

Radiotherapy resistance is a commonly encountered problem in cancer treatment. In this regard, stabilization of endothelial cells and release of angiogenic factors by cancer cells contribute to this problem. In this study, we used human lung adenocarcinoma (A549) cells to compare the effects of carbon ion and X-ray irradiation on the cells' angiogenic response.

METHODS AND MATERIALS

A549 cells were irradiated with biologically equivalent doses for cell survival of either carbon ions (linear energy transfer, 170 keV/μm; energy of 9.8 MeV/u on target) or X-rays and injected with basement membrane matrix into BALB/c nu/nu mice to generate a plug, allowing quantification of angiogenesis by blood vessel enumeration. The expression of angiogenic factors (VEGF, PlGF, SDF-1, and SCF) was assessed at the mRNA and secreted protein levels by using real-time reverse transcription-PCR and enzyme-linked immunosorbent assay. Signal transduction mediated by stem cell factor (SCF) was assessed by phosphorylation of its receptor c-Kit. For inhibition of SCF/c-Kit signaling, a specific SCF/c-Kit inhibitor (ISCK03) was used.

RESULTS

Irradiation of A549 cells with X-rays (6 Gy) but not carbon ions (2 Gy) resulted in a significant increase in blood vessel density (control, 20.71 ± 1.55; X-ray, 36.44 ± 3.44; carbon ion, 16.33 ± 1.03; number per microscopic field). Concordantly, irradiation with X-rays but not with carbon ions increased the expression of SCF and subsequently caused phosphorylation of c-Kit in endothelial cells. ISCK03 treatment of A549 cells irradiated with X-rays (6 Gy) resulted in a significant decrease in blood vessel density (X-ray, 36.44 ± 3.44; X-ray and ISCK03, 4.33 ± 0.71; number of microscopic field). These data indicate that irradiation of A549 cells with X-rays but not with carbon ions promotes angiogenesis.

CONCLUSIONS

The present study provides evidence that SCF is an X-ray-induced mediator of angiogenesis in A549 cells, a phenomenon that could not be observed with carbon ion irradiation. Thus, in this model system evaluating angiogenesis, carbon ion irradiation may have a therapeutic advantage. This observation should be confirmed in orthotopic lung tumor models.

Rapamycin synergizes with low-dose oxaliplatin in the HCT116 colon cancer cell line by inducing enhanced apoptosis

The present study aimed to examine the combined effects of oxaliplatin (L-OHP) and rapamycin (RAPA) in the HCT116 colon cancer cell line. The growth inhibitory effect was evaluated by MTT assay as a monotherapy or combination therapy. IC(50) values were determined using CalcuSyn 2.0 software. To determine the interaction of the drugs, the combination index (CI) was calculated using the Chou-Talalay method. Apoptosis was investigated using flow cytometry and Western blotting. Acridine orange staining was employed to observe morphological changes. The results showed the IC(50) values of L-OHP and RAPA to be 8.35±0.78 μM (r=0.99) and 223.44±38.10 nM (r=0.94), respectively. CI was ≤1 when L-OHP was used at doses ranging from 1 to 5 μM plus RAPA at a dose of 10 nM, suggesting synergistic or additive effects. CI was ≥1 when 100 nM RAPA was used in combination with low-dose L-OHP, showing additive to antagonistic effects. The combination of L-OHP (1 μM) and RAPA (10 nM) induced 19.76% Annexin V-positive cells, which was found to be higher than L-OHP (11.45%, p<0.01) or RAPA (6.89%, p<0.01) alone. The cleaved PARP protein expression levels were highest after 48 h of combination treatment. Acridine orange staining showed typical bright red Acidic vesicular organelles in the RAPA group, whereas the green condensed chromatin in the apoptotic bodies was found in both the L-OHP and combination groups. In conclusion, at a cytostatic concentration, RAPA was found to potentiate the anti-tumor effects of low-dose L-OHP in the HCT116 colon cancer cell by inducing enhanced apoptosis.

Radioimmunotherapy of solid tumors: searching for the right target

Radioimmunotherapy of solid tumors remains a challenge despite the tremendous success of ⁹⁰Y ibritumomab tiuxetan (Zevalin) and ¹³¹I Tositumomab (Bexxar) in treating non-Hodgkin's lymphoma. For a variety of reasons, clinical trials of radiolabeled antibodies against solid tumors have not led to responses equivalent to those seen against lymphoma. In contrast, promising responses have been observed with unlabeled antibodies that target solid tumor receptors associated with cellular signaling pathways. These observations suggest that anti-tumor efficacy of the carrier antibody might be critical to achieving clinical responses. Here, we review and compare tumor antigens targeted by radiolabeled antibodies and unlabeled antibodies used in immunotherapy. The review shows that the trend for radiolabeled antibodies under pre-clinical development is to also target antigens associated with signaling pathways that are essential for the growth and survival of the tumor.

Development of an ErbB-overexpressing A-431 optical reporting tumor xenograft model to assess targeted photodynamic therapy regimens

To better assess the efficacy of erbB-targeted therapies, it would help to have optical reporting human tumor xenograft models that abundantly express erbB receptors. A-431 cells have frequently been used in erbB1-targeting studies, but a well-characterized optical reporting version of the cell line has not been readily available. In this study, optical reporting A-431 clones were developed that express both a fluorescent protein reporter (green, GFP; or red, RFP) and a bioluminescent reporter, firefly luciferase. Reporter genes were transduced into cells using commercial lentiviral vectors, and clonal selection was carried out using a series of procedures. A number of clones were isolated for further characterization. A GFP/luciferase clone, A-431/D4, and an RFP/luciferase clone, A-431/G4, were obtained that exhibit erbB1 expression levels and tumor growth kinetics similar to the parental cells. To demonstrate the utility of the optical reporting clones, A-431/G4 tumors were grown subcutaneously in nude mice and treated with vascular-targeted photodynamic therapy (PDT), which targets the angiogenic consequences of erbB signaling. The A-431/G4 tumor model permitted highly sensitive longitudinal monitoring of PDT treatment response using optical imaging. A-431/D4 and A-431/G4 optical reporting tumor models should also prove useful for assessing therapies that directly target the erbB1 receptor.