Current role of antibody therapy in patients with metastatic colorectal cancer

Effects of Chemotherapy for Metastatic Colorectal Cancer on the TGF-β Signaling and Related miRNAs hsa-miR-17-5p, hsa-miR-21-5p and hsa-miR-93-5p

Metastatic colorectal cancer (mCRC) patients are treated with standard chemotherapeutic drugs in the form of FOLFOX and FOLFIRI regimens. There are no reliable markers that could predict response to chemotherapy for mCRC. TGF-β signaling which interacts with microRNA (miRNA) network has important roles in tumor progression and chemotherapy resistance, thus the interplay between TGF-β signaling and miRNAs could be crucial for treatment response. The aim of this study was to analyze the effect of chemotherapy for mCRC on TGF-β signaling and related miRNAs. Hsa-miR-17-5p, hsa-miR-21-5p and hsa-miR-93-5p were selected out of 316 miRNAs with multiple targets within the TGF-β signaling by in silico analysis. SW620 cells were treated with chemotherapeutic drugs for mCRC for 1, 3 and 6 days and expression of selected miRNAs, PAI-1, CDH1 and VIM was measured. Expression of TGF-β signaling-related hsa-miR-17-5p, hsa-miR-21-5p and hsa-miR-93-5p was time-dependently altered in SW620 cells treated with chemotherapeutics for mCRC. The expression of hsa-miR-93-5p remained downregulated after 6 days under combined treatments FOX and FIRI as well as the hsa-miR-17-5p expression under FIRI. Chemotherapy regimens for mCRC increased expression of a major TGF-β signaling target gene PAI-1, independently of the selected miRNAs expression. These treatments also increased the expression of epithelial-mesenchymal transition (EMT) markers CDH1 and VIM on day 3 resulting in decrease of mesenchymal-like characteristics. However, their expression returned close to basal level on day 6. In conclusion, after initial response to chemotherapeutic drugs SW620 cells start to return close to the basal mesenchymal state while the long-term downregulated expression pattern of hsa-miR-93-5p and hsa-miR-17-5p makes them candidates worth testing as biomarkers for monitoring combined chemotherapeutic treatments therapy response in mCRC patients.

Coexpression of Matrix Metalloproteinase-7 and Tissue Inhibitor of Metalloproteinase-1 as a Prognostic Biomarker in Gastric Cancer

Background

Degradation of the extracellular matrix (ECM), an essential step in tumour invasion and metastasis, is mainly dependent on the activities of both matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). This study aimed to explore whether expression of MMP-7 and TIMP-1 alone and in combination can be used as a prognostic marker for gastric cancer (GC).

Method

A total of 285 patients who had undergone tumourectomy for GC were included. Gastric tumour tissues were stained immunohistochemically to evaluate expression of MMP-7 and TIMP-1.

Results

Expression of MMP-7 was associated with tumour N stage and neural invasion. Multivariate Cox regression analysis suggested that expression of MMP-7 or TIMP-1 alone cannot serve as an indicator of patient prognosis; however, coexpression of MMP-7 and TIMP-1 was found to be an independent predictive factor of overall survival in patients with GC (HR = 1.74, 95% CI: 1.08-2.80). The results of stratified analysis also showed that the predictive value of MMP-7 and TIMP-1 coexpression was stronger in patients with N3 stage disease and not receiving chemotherapy.

Conclusions

In conclusion, coexpression of MMP-7 and its inhibitor TIMP-1 in gastric tumour tissues is a potential prognostic marker for GC. Greater knowledge of protein expression will lead to new paradigms and possible improvements in therapeutics.

Long noncoding RNA ARSR is associated with a poor prognosis in patients with colorectal cancer

BACKGROUND

As one of the leading cancer-related mortalities worldwide, colorectal cancer (CRC) shows resistance to chemotherapy mainly because of drug resistance. Existing evidence has revealed that long noncoding RNAs (lncRNAs) are related to tumorigenesis and chemoresistance scenarios. However, the mechanism by which lncRNA induces chemoresistance and the postoperative prognosis of CRC both remain unclear.

METHODS

The expression of a lncRNA named lncARSR in CRC tissue was tested, and its association with clinical and pathological features was analyzed. Gain-of-function and loss-of-function assays were conducted to investigate the role of lncARSR in vivo and in vitro.

RESULTS

Functional analysis showed that overexpressing lncARSR increased oxaliplatin (OXA) resistance of CRC cells in vitro and in vivo. Moreover, lncARSR conferred chemoresistance to CRC cells. Silencing lncARSR decreased cell viability and promoted cell apoptosis after OXA treatment, whereas overexpression of lncARSR increased cell viability and reduced cell apoptosis after OXA treatment. In addition, lncARSR overexpression induced the tumor formation capacity of colorectal cancer cells.

CONCLUSIONS

The results obtained in the present study show that up-regulation of lncARSR promoted OXA resistance in CRC. Our results also imply that lncARSR may be a candidate marker for CRC chemoresistance.

Panitumumab-Conjugated and Platinum-Cored pH-Sensitive Apoferritin Nanocages for Colorectal Cancer-Targeted Therapy

Apoferritin (AF) is a natural nontoxic iron carrier and has a natural hollow structure that can be used to deliver small molecules. The surface of AF has many amine functional groups that can be modified to create targeted ligands. We loaded oxaliplatin onto AF, which was then used as a template to conjugate with panitumumab via a polyethylene glycol linker. The oxaliplatin-loaded AF conjugated with panitumumab (AFPO) was designed to specifically target cell lines expressing epidermal growth factor receptor (EGFR). AFPO efficiently released oxaliplatin and suppressed tumor cell growth. Furthermore, the novel AFPO nanocages showed significant inhibition and greater accumulation in tumor models with high EGFR expression in vivo. Our study revealed that combining panitumumab and oxaliplatin into one formulation (AFPO nanocage) could be a promising shortcut in clinical applications.

MEG3 is a prognostic factor for CRC and promotes chemosensitivity by enhancing oxaliplatin-induced cell apoptosis

A major reason for the failure of advanced colorectal cancer (CRC) treatment is the occurrence of chemoresistance to oxaliplatin-based chemotherapy. Recently, studies have shown that long non-coding RNAs (lncRNAs) play an important role in drug resistance. Using HiSeq sequencing methods, we identified that lncRNAs show differential expression levels in oxaliplatin-resistant (OxR) and non-resistant CRC patients. RT-qPCR was then performed in tissues and serum samples, and lncRNA MEG3 was verified to be downregulated in non-responding patients and to have considerable discriminating potential to identify responding patients from non-responding patients. Moreover, decreased serum MEG3 expression was associated with poor chemoresponse and low survival rate in CRC patients receiving oxaliplatin treatment. Subsequently, OxR cell lines were established, and MEG3 was significantly downregulated in HT29 OxR and SW480 OxR cells. In addition, overexpression of MEG3 with pMEG3 reversed oxaliplatin resistance in both CRC cell lines. Flow cytometric apoptosis analysis indicated that MEG3 promoted CRC cell apoptosis. More importantly, MEG3 enhanced oxaliplatin‑induced cell cytotoxicity in CRC. In conclusion, our integrated approach demonstrated that decreased expression of lncRNA MEG3 in CRC confers potent poor therapeutic efficacy, and that MEG3 promotes chemosensitivity by enhancing oxaliplatin-induced cell apoptosis. Thus, overexpression of MEG3 may be a future direction by which to develop a novel therapeutic strategy to overcome oxaliplatin resistance of CRC patients.

Label-Free Raman Spectroscopic Imaging Monitors the Integral Physiologically Relevant Drug Responses in Cancer Cells

Predictions about the cellular efficacy of drugs tested in vitro are usually based on the measured responses of a few proteins or signal transduction pathways. However, cellular proteins are highly coupled in networks, and observations of single proteins may not adequately reflect the in vivo cellular response to drugs. This might explain some large discrepancies between in vitro drug studies and drug responses observed in patients. We present a novel in vitro marker-free approach that enables detection of cellular responses to a drug. We use Raman spectral imaging to measure the effect of the epidermal growth factor receptor (EGFR) inhibitor panitumumab on cell lines expressing wild-type Kirsten-Ras (K-Ras) and oncogenic K-Ras mutations. Oncogenic K-Ras mutation blocks the response to anti-EGFR therapy in patients, but this effect is not readily observed in vitro. The Raman studies detect large panitumumab-induced differences in vitro in cells harboring wild-type K-Ras as seen in A in red but not in cells with K-Ras mutations as seen in B; these studies reflect the observed patient outcomes. However, the effect is not observed when extracellular-signal-regulated kinase phosphorylation is monitored. The Raman spectra show for cells with wild-type K-Ras alterations based on the responses to panitumumab. The subcellular component with the largest spectral response to panitumumab was lipid droplets, but this effect was not observed when cells harbored K-Ras mutations. This study develops a noninvasive, label-free, in vitro vibrational spectroscopic test to determine the integral physiologically relevant drug response in cell lines. This approach opens a new field of patient-centered drug testing that could deliver superior patient therapies.

Neoadjuvant capecitabine, bevacizumab and radiotherapy for locally advanced rectal cancer: results of a single-institute Phase I study

The aim of this Phase I clinical trial was to assess the feasibility and safety of capecitabine-based preoperative chemoradiotherapy (CRT) combined with bevacizumab and to determine the optimal capecitabine dose for Japanese patients with locally advanced rectal cancer. Patients with cT3/T4 rectal cancer were eligible. Bevacizumab was administered at 5 mg/kg intravenously on Days 1, 15 and 29. Capecitabine was administered on weekdays concurrently with pelvic radiotherapy at a daily dose of 1.8 Gy, totally to 50.4 Gy. Capecitabine was initiated at 825 mg/m(2) twice daily at Dose Level 1, with a planned escalation to 900 mg/m(2) twice daily at Dose Level 2. Within 6.1-10.3 (median, 9.4) weeks after the completion of the CRT, surgery was performed. Three patients were enrolled at each dose level. Regarding the CRT-related acute toxicities, all of the adverse events were limited to Grade 1. There was no Grade 2 or greater toxicity. No patient needed attenuation or interruption of bevacizumab, capecitabine or radiation. All of the patients received the scheduled dose of CRT. All of the patients underwent R0 resection. Two (33.3%) of the six patients had a pathological complete response, and five (83.3%) patients experienced downstaging. In total, three patients (50%) developed postoperative complications. One patient developed an intrapelvic abscess and healed with incisional drainage. The other two patients healed following conservative treatment. This regimen was safely performed as preoperative CRT for Japanese patients with locally advanced rectal cancer. The recommended capecitabine dose is 900 mg/m(2) twice daily.

High expression of microRNA-625-3p is associated with poor response to first-line oxaliplatin based treatment of metastatic colorectal cancer

The backbone of current cytotoxic treatment of metastatic colorectal cancer (mCRC) consists of a fluoropyrimidine together with either oxaliplatin (XELOX/FOLFOX) or irinotecan (XELIRI/FOLFIRI). With an overall objective response rate of approximately 50% for either treatment combination, a major unsolved problem is that no predictors of response to these treatments are available. To address this issue, we profiled 742 microRNAs in laser-capture microdissected cancer cells from responding and non-responding patients receiving XELOX/FOLFOX as first-line treatment for mCRC, and identified, among others, high expression of miR-625-3p, miR-181b and miR-27b to be associated with poor clinical response. In a validation cohort of 94 mCRC patients treated first-line with XELOX, high expression of miR-625-3p was confirmed to be associated with poor response (OR = 6.25, 95%CI [1.8; 21.0]). Independent analyses showed that miR-625-3p was not dysregulated between normal and cancer samples, nor was its expression associated with recurrence of stage II or III disease, indicating that miR-625-3p solely is a response marker. Finally, we also found that these miRNAs were up-regulated in oxaliplatin resistant HCT116/oxPt (miR-625-3p, miR-181b and miR-27b) and LoVo/oxPt (miR-181b) colon cancer cell lines as compared with their isogenic parental cells. Altogether, our results suggest an association between miR-625-3p and response to first-line oxaliplatin based chemotherapy of mCRC.

Glioma antigen

Because several antigenic peptides of human tumors that are recognized by T-lymphocytes have been identified, immune responses against cancer can now be artificially manipulated. Furthermore, since T-lymphocytes have been found to play an important role in the rejection of tumors by the host and also to have antigen-specific proliferative potentials and memory mechanisms, T-lymphocytes are thought to play a central role in cancer vaccination. Although multidisciplinary therapies have been attempted for the treatment of gliomas, the results remain unsatisfactory. For the development of new therapies against gliomas, it is required to identify tumor antigens as targets for specific immunotherapy. In this chapter, recent progress in research on glioma antigens is described.

Preparation of human scFv antibody against nasopharyngeal carcinoma and identification of its specificity

Abstract Conclusion: The selected scFv antibody could specifically recognize and target nasopharyngeal carcinoma (NPC), and could be applied to clinical diagnosis and therapy.

OBJECTIVE

The aim was to construct and screen fully human anti-NPC single chain Fv fusion phage libraries, and to identify the specificity of the scFv antibody.

METHODS

Peripheral blood mononuclear cells of patients with NPC were immunized in vitro by NPC cells and transformed by Epstein-Barr virus. The total RNAwas used to construct the scFv libraries. By means of ELISA and immunochemistry, the positively bound scFv was selected and identified. The positive scFv was fused to EGFP, and was then expressed in E. coli strain BL21 (DE3) and purified. Furthermore, we observed the binding bioactivity.

RESULTS

The fusion protein has the biological activity of binding the NPC cells and emitting green fluorescence. In targeting experiments in vivo, the results showed that the fusion protein can successfully target the NPC.

Dual inhibition of SRC and Aurora kinases induces postmitotic attachment defects and cell death

Increased activity of SRC family kinases promotes tumor invasion and metastasis, and overexpression of the mitotic regulator Aurora kinase A (AURKA) drives tumor aneuploidy and chromosomal instability. These functions nominate SRC and AURKA as valuable therapeutic targets for cancer, and inhibitors for SRC and Aurora kinases are now being used in the clinic. In this study, we demonstrate potent synergy between multiple inhibitors of Aurora and SRC kinases in ovarian and colorectal cancer cell lines, but not in normal ovarian epithelial cell lines. Combination of Aurora and SRC inhibitors selectively killed cells that have undergone a preceding aberrant mitosis, and was associated with a postmitotic reattachment defect, and selective removal of aneuploid cell populations. Combined inhibition of Aurora kinase and SRC potentiated dasatinib-dependent loss of activated (Y(416)-phosphorylated) SRC. SRC and AURKA share a common interaction partner, NEDD9, which serves as a scaffolding protein with activities in cell attachment and mitotic control, suggesting SRC and AURKA might interact directly. In vitro, we observed physical interaction and mutual cross-phosphorylation between SRC and AURKA that enhanced SRC kinase activity. Together, these findings suggest that combination of SRC and Aurora-targeting inhibitors in the clinic may be a productive strategy.

Resistance or sensitivity of Wilms' tumor to anti-FZD7 antibody highlights the Wnt pathway as a possible therapeutic target

Wilms' tumor (WT), the most frequent renal solid tumor in children, has been linked to aberrant Wnt signaling. Herein, we demonstrate that different WTs can be grouped according to either sensitivity or resistance to an antibody (Ab) specific to frizzled7 (FZD7), a Wnt receptor. In the FZD7-sensitive WT phenotype, the Ab induced cell death of the FZD7(+) fraction, which in turn depleted primary WT cultures of their clonogenic and sphere-forming cells and decreased in vivo proliferation and survival on xenografting to the chick chorio-allantoic-membrane. In contrast, FZD7-resistant WT in which no cell death was induced showed a different intra-cellular route of the Ab-FZD7 complex compared with sensitive tumors and accumulation of β-catenin. This coincided with a low sFRP1 and DKK1 (Wnt inhibitors) expression pattern, restored epigenetically with de-methylating agents, and lack of β-catenin or WTX mutations. The addition of exogenous DKK1 and sFRP1 to the tumor cells enabled the sensitization of FZD7-resistant WT to the FZD7 Ab. Finally, although extremely difficult to achieve because of dynamic cellular localization of FZD7, sorting of FZD7(+) cells from resistant WT, showed them to be highly clonogenic/proliferative, overexpressing WT 'stemness' genes, emphasizing the importance of targeting this fraction. FZD7 Ab therapy alone or in combination with Wnt pathway antagonists may have a significant role in the treatment of WT via targeting of a tumor progenitor population.

Panitumumab: the evidence for its use in the treatment of metastatic colorectal cancer

Panitumumab is the first fully human monoclonal antibody to Epidermal Growth Factor Receptor (EGFR) to enter clinical trials for the treatment of solid tumors. The anti-tumor activity of panitumumab has been tested in vitro and in vivo, and inhibition of tumor growth has been observed in numerous cancer models, particularly lung, kidney and colorectal (CRC). Preclinical and clinical studies have established a role for panitumumab in metastatic colorectal cancer (mCRC) refractory to multiple chemotherapeutic regimens. Based on these encouraging findings, panitumumab was approved by the US Food and Drug Administration for the treatment of patients with epidermal growth factor receptor-expressing mCRC refractory to fluoropyrimidine-, oxaliplatin-, and/or irinotecan-containing chemotherapeutic regimens. The improvement in progression free survival (PFS) and response rate (RR) produced by panitumumab monotherapy was significantly greater in patients with non mutated (wild-type) K-RAS than in those with mutant K-RAS. Therefore implementing routine K-RAS screening and limiting the use of EGFR inhibitors to patients with wild-type K-RAS appears the better strategy for select only the patients who could benefit from the therapy with panitumumab and also may have the potential for cost savings. The purpose of this review was to evaluate the patient-related, disease-related and economic-related evidence for the use of panitumumab in the treatment of metastatic colorectal cancer in clinical practice.

Gamma Knife surgery for brain metastases from colorectal cancer. Clinical article

OBJECT

The outcomes after Gamma Knife surgery (GKS) were retrospectively analyzed in patients with brain metastases from radioresistant primary colorectal cancer to evaluate the efficacy of GKS and the prognostic factors for local tumor control and overall survival.

METHODS

The authors reviewed the medical records of 152 patients with 616 tumors. The group included 102 men and 50 women aged 35-85 years (mean age 64.4 years), who underwent GKS for metastatic brain tumors from colorectal cancer between April 1992 and September 2008 at Yokohama Rosai Hospital.

RESULTS

The mean prescription dose to the tumor margin was 18.5 Gy (range 8-30 Gy). The mean tumor volume at GKS was 2.0 cm(3) (range 0.004-10.0 cm(3)). The primary tumors were located in the colon in 88 patients and the rectum in 64. The median interval between the diagnosis of primary lesions and the diagnosis of brain metastases was 27 months (range 0-180 months). The median neuroradiological follow-up period after GKS was 3 months (mean 6.4 months, range 1-93 months). The local tumor growth control rate, based on MR imaging, was 91.2%. The significant factors for unfavorable local tumor growth control, based on multivariate analysis, were larger tumor volume (p = 0.001) and lower margin dose (p = 0.016). The median overall survival time was 6 months. Lower Karnofsky Performance Scale (KPS) score (p = 0.026) and the presence of extracranial metastases (p = 0.004) at first GKS were significantly correlated with poor overall survival period in multivariate analysis. The cause of death was systemic disease in 112 patients and neurological disease in 13 patients. Leptomeningeal carcinomatosis was significantly correlated with a shorter duration of neurological survival in multivariate analysis (p < 0.0001).

CONCLUSIONS

Gamma Knife surgery is effective for suppression of local tumor growth in patients with brain metastases from radioresistant colorectal primary cancer. Therefore, clinical and radiological screening of intracranial metastases for patients with lower KPS scores and/or the presence of extracranial metastases as well as follow-up examinations after GKS for brain metastases should be performed periodically in patients with colorectal cancer, because the neurological prognosis is improved by initial and repeat GKS for newly diagnosed or recurrent tumors leading to a prolonged high-quality survival period.

Combined treatment with bevacizumab and standard chemotherapy restores abnormal immune parameters in advanced colorectal cancer patients

BACKGROUND

Bevacizumab, a monoclonal antibody (mAb) targeting vascular endothelial growth factor (VEGF), has produced promising results when combined with chemotherapy in the treatment of advanced colorectal cancer (CRC). The aim of the present study was to define the immunological profile of metastatic CRC patients at baseline and following chemotherapy with either irinotecan/5-fluorouracil/leucovorin (IFL) alone or IFL in combination with.bevacizumab (B-IFL).

METHODS

Peripheral blood mononuclear cells (PBMCs) obtained from healthy donors (HD) (n = 20) and patients (n = 40) were tested for T-cell proliferation in the autologous mixed lymphocyte reaction (auto-MLR), and cytokine production following stimulation with anti-CD3 mAb.

RESULTS

PBMCs obtained from CRC patients prior to treatment exhibited lower auto-MLR responses and low production of IL-2, IFN-γ, IL-12 and IL-18 cytokines, whereas IL-4 and IL-10 cytokines were increased as compared to HD (p < 0.001, for all parameters) following in vitro stimulation with anti-CD3 mAb. During treatment, and in particular in week 12 of evaluation, IL-2 (p < 0.001 for both IFL and B-IFL groups), IFN-γ (p < 0.001 for IFL and p = 0.001 for B-IFL), IL-12 (p < 0.001 for both IFL and B-IFL) and IL-18 (p < 0.001 for both IFL and B-IFL) production, as well as auto-MLR responses increased (p < 0.001 for both IFL and B-IFL), whereas IL-4 (p < 0.001 for IFL and p = 0.001 for B-IFL) and IL-10 [p < 0.001 for IFL and p = 0.067 (non-significant) for B-IFL] production decreased over baseline in the two treatment groups, yet their respective values never reached those of HD. Moreover, IL-2, IFN-γ production, and auto-MLR were higher in the B-IFL over the IFL treatment group (p < 0.001, p < 0.04, p < 0.001, respectively).

CONCLUSION

Our study demonstrates that the abnormal immune parameters observed in metastatic CRC patients at presentation can substantially improve during treatment with either IFL or B-IFL. The immune parameters examined can provide a sensitive and valuable tool for monitoring immune function in CRC patients, and could be applied as surrogate markers predicting treatment-related outcome.

Addition of sunitinib to cetuximab and irinotecan in patients with heavily pre-treated advanced colorectal cancer

Results of continuous sunitinib, in combination with cetuximab and irinotecan every other week (SIC) for compassionate use in heavily pre-treated patients with mCRC are presented.

PATIENTS AND METHODS

Patients with mCRC resistant to oxaliplatin, irinotecan, 5-FU and cetuximab received SIC at two Danish oncologic departments. The regimen consisted of sunitinib given as a continuous-dosing in combination with cetuximab and irinotecan every other week (CetIri). The first six patients started with a daily oral dose of sunitinib of 12.5 mg. Subsequent patients started at a daily dose of 25 mg with the possibility to escalate to 37.5 mg.

RESULTS

Twenty-nine patients received SIC. No patient had an objective response, but 13 patients had subjective relief and 42% had stable disease. The median time to progression was 3.2 months and median overall survival was 7.4 months. Fatigue and leukopenia were the most frequently reported severe adverse event (18% grade 3 and 18% grade 3/4, respectively).

DISCUSSION

Sunitinib continuous-dosing with 25 mg/day can safely be combined with CetIri administered every other week.

Plasma TIMP-1 levels and treatment outcome in patients treated with XELOX for metastatic colorectal cancer

BACKGROUND

The aim was to evaluate the association between plasma tissue inhibitor of metalloproteinase-1 (TIMP-1) and serum carcinoembryonic antigen (CEA) levels and outcome in patients with metastatic colorectal cancer (mCRC) receiving XELOX (combination chemotherapy with capecitabine and oxaliplatin) as first-line treatment.

PATIENTS AND METHODS

One hundred and twenty patients were included. Blood samples were collected before treatment and 3 weeks later before the next treatment cycle. Plasma TIMP-1 and serum CEA levels were correlated to treatment outcome.

RESULTS

No significant associations between baseline TIMP-1 or CEA levels and best response to treatment or progression-free survival (PFS) could be demonstrated. In contrast, high baseline plasma TIMP-1 levels were associated with poor overall survival (OS), P = 0.008, hazard ratio (HR) = 1.80 [95% confidence interval (CI): 1.17-2.78]. Furthermore, increase in TIMP-1 levels from baseline to immediately before the second cycle of chemotherapy had a significant negative effect on survival (P = 0.03, HR = 1.30, 95% CI: 1.02-1.65) while a decrease in TIMP-1 was significantly associated with a higher objective response rate (P = 0.03).

CONCLUSIONS

Both high baseline and subsequent increase in TIMP-1 levels were associated with shorter OS in patients with mCRC receiving XELOX as first-line treatment, whereas baseline TIMP-1 levels were not associated with response or PFS following XELOX treatment.

Efficacy of the monoclonal antibody EGFR inhibitors for the treatment of metastatic colorectal cancer

Two anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (MoAbs) have been approved in Canada for the treatment of metastatic colorectal cancer (mCRC) - cetuximab, a mouse-human chimeric MoAb, and panitumumab, a fully human MoAb. This paper reviews the efficacy of the anti-EGFR monoclonal antibodies cetuximab and panitumumab - both as monotherapy and in combination with cytotoxic chemotherapy - in the treatment of mCRC. Both cetuximab and panitumumab have demonstrated clinical efficacy in monotherapy in patients with mCRC, an advantage that has recently been found to be limited largely to those with wild-type KRAS tumors. Advantages of using these agents in monotherapy include reduced cost and toxicity. While the addition of cetuximab to irinotecan has shown superior progression-free survival and response compared with cetuximab monotherapy, there is currently no evidence for a benefit of panitumumab in combination with irinotecan.

Construction and selection of human Fab antibody phage display library of liver cancer

The aim of this study was to construct the fully humanized anti-hepatoma Fab fragment phage libraries and select antibodies against hepatoma specifically. PBMCs of liver cancer patients were immunized in vitro with HpeG(2) cells and were then transformed by Epstein-Barr virus (EBV). After total RNA was extracted, the heavy chain Fd and kappa/lambda light chain were amplified by RT-PCR and cloned into the vector pComb3 to construct the libraries of Fab fragments. The libraries were then panned by HpeG(2) cells. By means of ELISA and immunochemistry, the Fab phage antibodies binding with hepatoma were selected and identified. The Fd and light chain PCR products were subsequently inserted into pComb3, and the volume of Fab libraries reached 1.7 x 10(7). The libraries were enriched about 138-fold by three cycles of panning. 540 phage clones were picked randomly. Using cell ELISA and immunohistochemistry with cultured cells, one clone Fab phage antibody, which had binding activity with hepatoma, was picked out. Fully humanized anti-hepatoma Fab antibody phage display libraries were constructed. One phage clone was selected and confirmed to specifically bind to hepatoma cells. The selected Fab antibody may be further developed and applied to clinical diagnosis and therapy.

Epidermal growth factor receptor expression discrepancies in metastatic colorectal cancer patients treated with cetuximab plus irinotecan-based chemotherapy refractory to irinotecan and oxaliplatin

PURPOSE

This study was designed to evaluate the efficacy and safety of cetuximab plus irinotecan-based therapy in metastatic colorectal cancer refractory to irinotecan and oxaliplatin. In addition, discrepancies in the expression of epidermal growth factor receptor were examined by immunohistochemistry using two different antibodies.

METHODS

The records of patients with metastatic colorectal cancer who were heavily pretreated with irinotecan and oxaliplatin and subsequently received cetuximab plus irinotecan-based therapy were reviewed. Differences in the expression of epidermal growth factor receptor detected by the PharmDx antibody and the clone H11 antibody in these patients were compared.

RESULTS

Between February 2005 and August 2007, 52 patients were treated; median age was 53.5 years. The confirmed overall response rate was 30.8 percent, and the disease control rate was 67.3 percent. Median time to progression was 3.1 months, and median overall survival was 8.1 months. Of the 27 patients evaluable for epidermal growth factor receptor status, epidermal growth factor receptor expression was positive in 12 patients (44.4 percent) using the clone H11 antibody test and in 26 patients (96.3 percent) with the PharmDx kit.

CONCLUSION

Cetuximab plus irinotecan-based therapy showed promising antitumor activity even in patients with metastatic colorectal cancer refractory to irinotecan and oxaliplatin. In addition, discrepancies in the expression of the epidermal growth factor receptor detected by the clone H11 antibody and the PharmDx kit were observed.

A novel antiangiogenic effect for telomerase-specific virotherapy through host immune system

Soluble factors in the tumor microenvironment may influence the process of angiogenesis; a process essential for the growth and progression of malignant tumors. In this study, we describe a novel antiangiogenic effect of conditional replication-selective adenovirus through the stimulation of host immune reaction. An attenuated adenovirus (OBP-301, Telomelysin), in which the human telomerase reverse transcriptase promoter element drives expression of E1 genes, could replicate in and cause selective lysis of cancer cells. Mixed lymphocyte-tumor cell culture demonstrated that OBP-301-infected cancer cells stimulated PBMC to produce IFN-gamma into the supernatants. When the supernatants were subjected to the assay of in vitro angiogenesis, the tube formation of HUVECs was inhibited more efficiently than recombinant IFN-gamma. Moreover, in vivo angiogenic assay using a membrane-diffusion chamber system s.c. transplanted in nu/nu mice showed that tumor cell-induced neovascularization was markedly reduced when the chambers contained the mixed lymphocyte-tumor cell culture supernatants. The growth of s.c. murine colon tumors in syngenic mice was significantly inhibited due to the reduced vascularity by intratumoral injection of OBP-301. The antitumor as well as antiangiogenic effects, however, were less apparent in SCID mice due to the lack of host immune responses. Our data suggest that OBP-301 seems to have antiangiogenic properties through the stimulation of host immune cells to produce endogenous antiangiogenic factors such as IFN-gamma.

Pharmacogenomic approach for the identification of novel determinants of acquired resistance to oxaliplatin in colorectal cancer

Oxaliplatin is a third-generation platinum agent used in colorectal cancer treatment. Oxaliplatin resistance acquisition is a complex process mainly based on alteration of genes and pathways involved in its mechanism of action. Therefore, our purpose was to perform a gene expression screening in an in vitro model to identify genes that could play a role in oxaliplatin resistance acquisition processes. Four colorectal cancer cell lines and their oxaliplatin-resistant derived sublines were compared. Microarray analysis was done using Human 19K Oligo Array Slides. RNA from cells were hybridized with a commercial RNA reference sample and labeled with both fluorochromes Cy3 and Cy5. Data were analyzed by hierarchical clustering method. Subsequently, quantitative real-time PCR (qRT-PCR) was used to corroborate microarray data, considering as positively validated those genes that showed significant differences in expression levels between groups and a correlation between microarray and qRT-PCR data. By microarray analysis, 32 candidate genes were identified. After validation process by qRT-PCR, the genes AKT1, CDK5, TRIP, GARP, RGS11, and UGCGL1 were positively validated. The 3 first genes proved to be involved in regulation of nuclear factor-kappabeta antiapoptotic transcription factor previously related to drug resistance, and the other 3 genes are novel finds. We have identified 6 genes related to oxaliplatin resistance acquisition. These findings are of paramount importance to understand these processes better and open new lines of study to elucidate the relevance of this pharmacogenomic approach into the clinic.

Clinical use of anti-epidermal growth factor receptor monoclonal antibodies in metastatic colorectal cancer

Abstract Cetuximab and panitumumab, monoclonal antibodies used to target the epidermal growth factor receptor (EGFR), were recently approved by the United States Food and Drug Administration for use as single agents or in combination with other chemotherapy drugs in the treatment of metastatic colorectal cancer. The anti-EGFR monoclonal antibodies, either as single agents or in combination with chemotherapy, have demonstrated clinical activity in this setting. When combined with standard cytotoxic chemotherapy or other targeted agents (e.g., bevacizumab, an anti-vascular endothelial growth factor monoclonal antibody), anti-EGFR monoclonal antibodies have been well tolerated and produced minimal toxicities. However, cetuximab and panitumumab appear to benefit only select patients. Predictive markers of efficacy, including EGFR overexpression, development of skin rash, and the absence of a K-ras mutation, have been evaluated in clinical studies to identify patients likely to respond to anti-EGFR monoclonal antibody therapy. This review discusses recent clinical studies of anti-EGFR monoclonal antibodies in the treatment of metastatic colorectal cancer, predictive markers of their efficacy, and common toxicities associated with their use.

The internally truncated LRP5 receptor presents a therapeutic target in breast cancer

Background

Breast cancer is a common malignant disease, which may be caused by a number of genes deregulated by genomic or epigenomic events. Deregulated WNT/β-catenin signaling with accumulation of β-catenin is common in breast tumors, but mutations in WNT signaling pathway components have been rare. An aberrantly spliced internally truncated LRP5 receptor (LRP5Δ666–809, LRP5Δ) was shown recently to be resistant to DKK1 inhibition, and was required for β-catenin accumulation in hyperparathyroid tumors and parathyroid tumor growth.

Methodology/Principal Findings

Here we show, by reverse transcription PCR and Western blot analysis, that LRP5Δ is frequently expressed in breast tumors of different cancer stage (58–100%), including carcinoma in situ and metastatic carcinoma. LRP5Δ was required in MCF7 breast cancer cells for the non-phosphorylated active β-catenin level, transcription activity of β-catenin, cell growth in vitro, and breast tumor growth in a xenograft SCID mouse model. WNT3 ligand, but not WNT1 and WNT3A augmented the endogenous β-catenin activity of MCF7 cells in a DKK1-insensitive manner. Furthermore, an anti-LRP5 antibody attenuated β-catenin activity, inhibited cell growth, and induced apoptosis in LRP5Δ-positive MCF7 and T-47D breast cancer cells, but not in control cells.

Conclusions/Significance

Our results suggest that the LRP5Δ receptor is strongly implicated in mammary gland tumorigenesis and that its aberrant expression present an early event during disease progression. LRP5 antibody therapy may have a significant role in the treatment of breast cancer.

Circulating tumour cells as a predictive factor for response to systemic chemotherapy in patients with advanced colorectal cancer

Circulating tumour cells (CTC) can be traced in patients with different types of cancer. The aim of this study was to detect CTC in patients with advanced colorectal cancer and whether CTC are still detectable after systemic chemotherapy. Blood from 34 patients with advanced colorectal cancer was analysed for the presence of CTC before chemotherapy was given and after 3 months. Eleven patients demonstrated a tumour remission after chemotherapy. In 6 cases CTC were detectable before but not after initiation of chemotherapy. Ten patients demonstrated a progression. In 5 cases CTC were detected before and after chemotherapy. Our data suggest that the detection of CTC will help to identify patients responding to chemotherapy or with a risk of a therapy failure.

Interleukin-2 potentiation of cetuximab antitumor activity for epidermal growth factor receptor-overexpressing gastric cancer xenografts through antibody-dependent cellular cytotoxicity

Cetuximab, a chimeric monoclonal antibody to epidermal growth factor receptor (EGFR), has been proved to have clinically significant antitumor activity against advanced colorectal cancers, but its therapeutic activity for gastric cancers remains unclear. In the present study, we investigated the antitumor effect and action mechanism of cetuximab using EGFR high-expressing (MKN-28) and EGFR low-expressing (GLM-1) gastric cancer cell lines without gene amplification. Cetuximab showed neither significant growth inhibition nor induction of apoptosis in either cell line in vitro, and only slightly inhibited ligand-induced phosphorylation of protein kinase B and extracellular signal-regulated kinase in MKN-28 cells. In contrast, cetuximab significantly inhibited subcutaneous and intraperitoneal tumor growth of MKN-28 cells, but not GLM-1 cells, in nude mice. This antitumor activity was significantly enhanced and diminished in nude mice by treatment with interleukin-2 (IL-2) and antiasialo GM1 antibody, which can expand and deplete natural killer (NK) cells, respectively. Antibody-dependent cellular cytotoxicity (ADCC) of cetuximab, as measured by (51)Cr release assay, was significantly higher in MKN-28 than in GLM-1 cells. This ADCC activity was enhanced by IL-2 and reduced by heat-aggregate of human immunoglobulin G, an inhibitor for FcR-III of NK cells. These results suggest that cetuximab in combination with IL-2 shows significant antitumor activity against EGFR high-expressing gastric cancer mainly through NK cell-mediated ADCC. Combination therapy with cetuximab and IL-2 would thus offer a new potential therapeutic approach for a subset of EGFR-overexpressing gastric cancers.

Cutaneous adverse reactions to therapeutic monoclonal antibodies for cancer

Advances in molecular biology have led to the successful development of targeted monoclonal antibodies to several types of malignancies. By June 2007, nine therapeutic monoclonal antibodies had been approved by the US Food and Drug Administration to treat various human cancers. In general, the adverse reactions of these agents have been milder than their cytotoxic chemotherapy counterparts, but side effects do occur. Cutaneous adverse reactions to the first of these agents were rare, and primarily limited to infusion reactions, local inflammation at injection sites, and ill-defined transient eruptions. However, the use of monoclonal antibody therapy against the epidermal growth factor receptor-1 in gastrointestinal and head and neck cancer has been frequently associated with significant skin reactions. As the use of these agents becomes more widespread, the recognition and management of these skin reactions becomes an increasingly important part of patient care.

Immunotherapy for gastrointestinal cancer: current status and strategies for improving efficacy

BACKGROUND

Despite improvement in conventional strategies for treating gastrointestinal (GI) carcinoma, large numbers of patients still suffer from incurable or progressive disease.

OBJECTIVE

Here we consider the prospects for circumventing limitations and maximising the efficacy of different immunotherapies.

METHODS

We summarise different cancer vaccines and targeted drugs and highlight the scientific rationale of using immunotherapy for targeting GI cancers, in addition to the potential strategies for improving immunotherapeutic efficacy.

RESULTS/CONCLUSION

Many cancer vaccines and antibody-directed therapies have been tested in early phase clinical trials and demonstrated proof of concept and safety. As yet few have been properly evaluated for clinical efficacy; although adoptive transfer of tumour-associated-antigen-specific T cells has shown dramatic clinical responses in some patients. The recognition of a role for T regulatory cells in limiting anti-tumour immunity has provided momentum for developing strategies to over-ride such immunoinhibitory effects. There is some evidence that conventional therapies may work by influencing these negative factors and allowing expression of immune control mechanisms. An important developing area for clinical evaluation is the testing of combined conventional and immunotherapeutic modalities which may provide for synergy; thereby circumventing the limitations of individualised treatments and generating additional clinical benefits.

Construction of humanized carcinoembryonic antigen specific single chain variable fragment and mitomycin conjugate

AIM: To construct a new target-oriented conjugate of humanized carcinoembryonic antigen (CEA) specific single chain variable fragment (scFv) and mitomycin (MMC) against colorectal cancer, and to investigate its influence on the growth and apoptosis of colorectal cancer cells.

METHODS: The primer was designed according to the gene sequence described in reference 16, which respectively contains restriction enzyme cleavage sites BamHI and EcoRI in its upstream and downstream. PCR was performed with the plasmid as template containing genes of humanized anti-CEA scFv. The product was digested by BamHI and EcoRI, and connected to an expression vector which also has the restriction enzyme cleavage sites BamHI and EcoR. Expression of the reaction was induced by isopropy-β -D-thiogalactoside (IPTG). Then the expression product was covalently coupled with MMC by dextran T-40. The immunoreactivity of the conjugate against colorectal cancer cells as well as CEA was measured by enzyme linked immunosorbent assay (ELISA). The inhibiting ratio of conjugate on the growth of colorectal cancer cells was also measured by ELISA. The effect of conjugate on the apoptosis of colorectal cancer cells was determined by flow cytometry (FCM).

RESULTS: Restriction endonuclease cleavage and gene sequencing confirmed that the expression vector was successfully constructed. Sodium dodecyl sulfate polyacrylamide gel electropheresis (SDS-PAGE) confirmed that this vector correctly expressed the fusion protein. ELISA confirmed that the conjugate had quite a strong immunoreactivity against colorectal cancer cells and CEA. The conjugate had inhibitory effects on colorectal cancer cells in a concentration-dependent manner and could induce apoptosis of colorectal cancer cells in a concentration-dependent manner.

CONCLUSION: The CEA-scFv-MMC conjugate can be successfully constructed and is able to inhibit the growth and induce apoptosis of colorectal cancer cells.