A gene expression predictor of response to EGFR-targeted therapy stratifies progression-free survival to cetuximab in KRAS wild-type metastatic colorectal cancer

The Clinical Relevance of Frequent Germline Genetic Variants Detected by Targeted Sequencing in Patients With Rectal Adenocarcinoma (READ)

BACKGROUND

The progression of colorectal cancer (CRC) mainly stems from the occurrence of somatic mutation. However, there is little information that can be used to comprehensively analyse the importance of germline variants in CRC patients.

PATIENTS AND METHODS

The candidate germline variants between tumor relapse and cured rectal adenocarcinoma (READ) were firstly filtered by whole-exome sequencing (n=4), and validated by targeted sequencing and associated with clinical outcome in READ (n=48).

RESULTS

We identified 9 pathogenic germline variants that were clinically associated with survival outcome in READ, including TIPIN, TLR1, TLR10, OR4D6, IGSF3, UBBP4, OR6J1, FAM208A and DISC1. Patients carrying these germline susceptibility variants had an increased risk of poor survival outcome compared to those without these variants.

CONCLUSION

Not only the tumor genome, but also the germline sequence must be analysed to depict the overall genetic profile, providing potential therapeutic strategies for personalized medicine.

Prognostic relevance of programmed cell death-ligand 1 expression and CD8+ TILs in rectal cancer patients before and after neoadjuvant chemoradiotherapy

PURPOSE/BACKGROUND

Radiotherapy has been recently reported to boost the therapeutic response of immune checkpoint blockade (ICB); however, few studies have focused on programmed cell death-ligand 1 (PD-L1) expression in locally advanced rectal cancer (LARC) patients who receive preoperative neoadjuvant chemoradiotherapy (neoCRT). The aim of the present study was to investigate the PD-L1 expression status and CD8+ intra-tumoral infiltrating lymphocytes (TILs) before and after neoCRT and its association with clinicopathological characteristics in rectal cancer.

MATERIALS AND METHODS

Immunostainings of PD-L1 and CD8+ TILs were performed in 112 pair-matched LARC patients treated by neoCRT. Tumor PD-L1 expression and CD8+ TILs within the tumor microenvironment before and after neoCRT were evaluated via immunohistochemistry.

RESULTS

High tumor PD-L1 expression was significantly increased from 50 to 63%, and high CD8+ TILs counts were also slightly increased from 32 to 35% after neoCRT treatment. High tumor PD-L1 before and after neoCRT was associated with improved disease-free survival (DFS, pre-neoCRT: p = 0.003 and post-neoCRT: p = 0.003) and overall survival (OS, pre-neoCRT: p = 0.045 and post-neoCRT: p = 0.0001). High CD8+ TILs before neoCRT was associated with improved DFS (p = 0.057), and it was significantly associated with improved DFS after neoCRT (p = 0.039). Patients with high tumor PD-L1 and CD8+ TILs before and after neoCRT were significantly associated with improved DFS (pre-neoCRT: p = 0.004 and post-neoCRT: p = 0.006).

CONCLUSION

The present results provide evidence that tumor PD-L1 expression and recruitment of CD8+ TILs within the tumor microenvironment were increased by neoCRT treatment. Tumor PD-L1 and CD8+ TILs are prognostic biomarkers for the survival of LARC patients treated with neoCRT.

Systems analysis identifies potential target genes to overcome cetuximab resistance in colorectal cancer cells

Cetuximab (CTX), a monoclonal antibody against epidermal growth factor receptor, is being widely used for colorectal cancer (CRC) with wild-type (WT) KRAS. However, its responsiveness is still very limited and WT KRAS is not enough to indicate such responsiveness. Here, by analyzing the gene expression data of CRC patients treated with CTX monotherapy, we have identified DUSP4, ETV5, GNB5, NT5E, and PHLDA1 as potential targets to overcome CTX resistance. We found that knockdown of any of these five genes can increase CTX sensitivity in KRAS WT cells. Interestingly, we further found that GNB5 knockdown can increase CTX sensitivity even for KRAS mutant cells. We unraveled that GNB5 overexpression contributes to CTX resistance by modulating the Akt signaling pathway from experiments and mathematical simulation. Overall, these results indicate that GNB5 might be a promising target for combination therapy with CTX irrespective of KRAS mutation.

Upregulation of tumor PD-L1 by neoadjuvant chemoradiotherapy (neoCRT) confers improved survival in patients with lymph node metastasis of locally advanced rectal cancers

The expression of programmed cell death 1 ligand 1 (PD-L1) and interferon-γ (IFN-γ) is of great interest for the development of chemoradiotherapy and immune checkpoint inhibitor treatments. Patients with nodal metastasis (pN+) tend to have a poor prognosis, even after neoadjuvant chemoradiotherapy (neoCRT) and surgical treatment. In this study, we examined the roles of tumor PD-L1 and IFN-γ before and after neoCRT in locally advanced rectal cancer (LARC) patients. Our results demonstrate that patients with high PD-L1 expression in post-neoCRT tissues exhibit improved 5-year disease-free survival (DFS) and overall survival (OS) compared with those with low PD-L1 expression (p < 0.001). Furthermore, in the pN+ population, patients with high PD-L1 expression in post-neoCRT tissues exhibit improved 5-year DFS and OS. PD-L1 and IFN-γ upregulation increased in tumor tissues after neoCRT, and patients with high PD-L1 and high IFN-γ exhibit improved 5-year DFS and OS (p = 0.04 and p = 0.001, respectively). To the best of our knowledge, this study is the first to demonstrate that PD-L1 upregulation in a pN+ cohort correlates with improved prognosis, which is similar to that in patients without nodal metastasis. Moreover, this study verified that PD-L1 and IFN-γ were upregulated by neoCRT treatment in LARC patients and demonstrated that neoCRT may be useful not only for immune checkpoint inhibitor treatment but also for reinvigorating preexisting anti-cancer immunity.

A Gene Expression Signature Predicts Bladder Cancer Cell Line Sensitivity to EGFR Inhibition

Background:

Bladder cancer remains a cancer type in need of novel and alternative therapies. While multiple inhibitors of EGFR have been evaluated for efficacy in bladder cancer, the results have largely been disappointing with few patients responding to these therapies. Yet, there is a subset of patients that positively responds to EGFR inhibition with tumor shrinkage, indicating it is an effective treatment for a targeted set of bladder tumors.

Objective:

To derive a gene expression signature capable of predicting the response to EGFR inhibition in bladder cancer cell lines.

Methods:

he response to cetuximab for 68 colorectal cancer patients was used as training data to generate a gene expression signature. We applied this signature to bladder cancer cell lines and predictions were compared to the responses to seven EGFR inhibitors.

Results:

A novel 67-gene signature derived from colorectal cancer was able to significantly identify bladder cancer cell lines by their response to several EGFR inhibitors.

Conclusions:

The 67-gene signature can determine bladder cancer cell line sensitivity to EGFR inhibition. This work demonstrates a preclinical strategy to identify bladder cancer cell lines for EGFR-targeted therapy.

Cytosolic high-mobility group box protein 1 (HMGB1) and/or PD-1+ TILs in the tumor microenvironment may be contributing prognostic biomarkers for patients with locally advanced rectal cancer who have undergone neoadjuvant chemoradiotherapy

Rectal cancer, which comprises 30% of all colorectal cancer cases, is one of the most common forms of cancer in the world. Patients with locally advanced rectal cancer (LARC) are often treated with neoadjuvant chemoradiotherapy (neoCRT) followed by surgery. However, after neoCRT treatment, approximately one-third of the patients progress to local recurrence or distant metastasis. In these studies, we found that patients with tumors that exhibited cytosolic HMGB1(Cyto-HMGB1) translocation and/or the presence of PD-1+ tumor-infiltrating lymphocytes (TILs) before treatment had a better clinical outcome. The better outcome is likely due to the release of HMGB1, which triggers the maturation of dendritic cells (DCs) via TLR4 activation, and the subsequent recruitment of PD-1+ tumor-infiltrating lymphocytes to the tumor site, where they participate in immune-scavenging. In conclusion, our results provide evidence that cyto-HMGB1 and/or PD-1+TIL are not only predictive biomarkers before treatment, but they can also potentially designate patients for personalized oncological management including immunotherapy.

Genomic markers of panitumumab resistance including ERBB2/ HER2 in a phase II study of KRAS wild-type (wt) metastatic colorectal cancer (mCRC)

A prospective study was conducted to identify biomarkers associated with resistance to panitumumab monotherapy in patients with metastatic colorectal cancer (mCRC). Patients with previously treated, codon 12/13 KRAS wt, mCRC were prospectively administered panitumumab 6 mg/kg IV q2weeks. Of 34 panitumumab-treated patients, 11 (32%) had progressive disease at 8 weeks and were classified as non-responders.

A Nanostring nCounter-based assay identified a 5-gene expression signature (ERBB2, MLPH, IRX3, MYRF, and KLK6) associated with panitumumab resistance (P = 0.001). Immunohistochemistry and in situ hybridization determined that the HER2 (ERBB2) protein was overexpressed in 4/11 non-responding and 0/21 responding cases (P = 0.035). Two non-responding tumors had ERBB2 gene amplification only, and one demonstrated both ERBB2 amplification and mutation. A non-codon 12/13 KRAS mutation occurred in one panitumumab-resistant patient and was mutually exclusive with ERBB2/HER2 abnormalities.

This study identifies a 5-gene signature associated with non-response to single agent panitumumab, including a subgroup of non-responders with evidence of aberrant ERBB2/HER2 signaling. KRAS wt tumors resistant to EGFRi may be identified by gene signature analysis, and the HER2 pathway plays an important role in resistance to therapy.

Pathway activation strength is a novel independent prognostic biomarker for cetuximab sensitivity in colorectal cancer patients

Cetuximab, a monoclonal antibody against epidermal growth factor receptor (EGFR), was shown to be active in colorectal cancer. Although some patients who harbor K-ras wild-type tumors benefit from cetuximab treatment, 40 to 60% of patients with wild-type K-ras tumors do not respond to cetuximab. Currently, there is no universal marker or method of clinical utility that could guide the treatment of cetuximab in colorectal cancer. Here, we demonstrate a method to predict response to cetuximab in patients with colorectal cancer using OncoFinder pathway activation strength (PAS), based on the transcriptomic data of the tumors. We first evaluated our OncoFinder pathway activation strength model in a set of transcriptomic data obtained from patient-derived xenograft (PDx) models established from colorectal cancer biopsies. Then, the approach and models were validated using a clinical trial data set. PAS could efficiently predict patients’ response to cetuximab, and thus holds promise as a selection criterion for cetuximab treatment in metastatic colorectal cancer.

Profile of selumetinib and its potential in the treatment of melanoma

The mitogen-activated protein kinase (MAPK) pathway is a critical oncogenic driver signal in a number of malignancies. The discovery of activating mutations in the MAPK pathway has led to the development of MAPK pathway inhibitors. Selumetinib is a potent and selective inhibitor of MEK1 and MEK2, which are essential downstream molecules in the MAPK pathway. Several preclinical and clinical studies have demonstrated the promising antitumor activity of selumetinib. In this review, we discuss the MAPK pathway in melanoma and summarized data from preclinical and clinical studies of selumetinib for advanced melanoma.

Molecular signatures of lung cancer: defining new diagnostic and therapeutic paradigms

Molecular profiling holds great promise for improving our ability to diagnose, prognosticate, and select individualized treatments for lung cancer patients. However, using multidimensional data and novel technologies to derive these profiles is limited by our ability to employ the assay in a clinical scenario where it can impact the course of disease. Although many molecular signatures have been reported in lung cancer, as of yet, few have been sufficiently validated for widespread clinical use. Recently, several novel signatures have been reported, which address critical aspects of patient care and/or demonstrate improved efforts for appropriate clinical validation. Here, we present our opinion on the current state of the field of molecular signatures in lung cancer.

The management of EGFR inhibitor adverse events: a case series and treatment paradigm

BACKGROUND

Epidermal growth factor receptor (EGFR) inhibitors are widely used medications in the treatment of cancers.

OBJECTIVE

To review the cutaneous adverse events related to EGFR inhibitors.

METHODS

A retrospective chart review of all cases referred for the management of cutaneous adverse events after the initiation of EGFR inhibitor therapy between the years of 2006 and 2009 was performed. The study was approved by the institutional review board.

RESULTS

Four men and 11 women had cutaneous adverse events while receiving erlotinib (mean dose: 112.5 mg) for lung and pancreatic cancer. The most common cutaneous adverse reaction observed was a papulopustular rash in 12 cases (80%). Eczema and xerosis were the only findings in three patients, alopecia in one case, and nail changes in three cases. The treatment modalities prescribed were doxycycline and topical antibiotics for the papulopustular rash; topical high potency steroids, tacrolimus, pimecrolimus, and moisturizers for xerosis and eczema; and cetirizine for the pruritus. The paronychia was treated with warm soaks, topical steroids, and podiatry referral. The majority of patients improved with symptomatic therapy, with the exception of one patient who experienced herpes zoster super infection and Stevens-Johnson syndrome. The patient was hospitalized and required discontinuation of the erlotinib therapy.

CONCLUSION

The most common cutaneous adverse event in our cohort was papulopustular rash, followed by eczema and xerosis. Patients were managed with symptom target therapy, and suspension of the EGFR inhibitor was rarely required. As the use of EGFR inhibitors increases, it is important to promptly identify and treat adverse events. Further studies are necessary to develop targeted therapeutic and preventative measures.

Array-based pharmacogenomics of molecular-targeted therapies in oncology

The advent of microarrays over the past decade has transformed the way genome-wide studies are designed and conducted, leading to an unprecedented speed of acquisition and amount of new knowledge. Microarray data have led to the identification of molecular subclasses of solid tumors characterized by distinct oncogenic pathways, as well as the development of multigene prognostic or predictive models equivalent or superior to those of established clinical parameters. In the field of molecular-targeted therapy for cancer, in particular, the application of array-based methodologies has enabled the identification of molecular targets with 'key' roles in neoplastic transformation or tumor progression and the subsequent development of targeted agents, which are most likely to be active in the specific molecular setting. Herein, we present a summary of the main applications of whole-genome expression microarrays in the field of molecular-targeted therapies for solid tumors and we discuss their potential in the clinical setting. An emphasis is given on deciphering the molecular mechanisms of drug action, identifying novel therapeutic targets and suitable agents to target them with, and discovering molecular markers/signatures that predict response to therapy or optimal drug dose for each patient.

Preclinical activity of the rational combination of selumetinib (AZD6244) in combination with vorinostat in KRAS-mutant colorectal cancer models

PURPOSE

Despite the availability of several active combination regimens for advanced colorectal cancer (CRC), the 5-year survival rate remains poor at less than 10%, supporting the development of novel therapeutic approaches. In this study, we focused on the preclinical assessment of a rationally based combination against KRAS-mutated CRC by testing the combination of the MEK inhibitor, selumetinib, and vorinostat, a histone deacetylase (HDAC) inhibitor.

EXPERIMENTAL DESIGN

Transcriptional profiling and gene set enrichment analysis (baseline and posttreatment) of CRC cell lines provided the rationale for the combination. The activity of selumetinib and vorinostat against the KRAS-mutant SW620 and SW480 CRC cell lines was studied in vitro and in vivo. The effects of this combination on tumor phenotype were assessed using monolayer and 3-dimensional cultures, flow cytometry, apoptosis, and cell migration. In vivo, tumor growth inhibition, (18)F-fluoro-deoxy-glucose positron emission tomography (FDG-PET), and proton nuclear magnetic resonance were carried out to evaluate the growth inhibitory and metabolic responses, respectively, in CRC xenografts.

RESULTS

In vitro, treatment with selumetinib and vorinostat resulted in a synergistic inhibition of proliferation and spheroid formation in both CRC cell lines. This inhibition was associated with an increase in apoptosis, cell-cycle arrest in G(1), and reduced cellular migration and VEGF-A secretion. In vivo, the combination resulted in additive tumor growth inhibition. The metabolic response to selumetinib and vorinostat consisted of significant inhibition of membrane phospholipids; no significant changes in glucose uptake or metabolism were observed in any of the treatment groups.

CONCLUSION

These data indicate that the rationally based combination of the mitogen-activated protein kinase/extracellular signal-regulated kinase inhibitor, selumetinib, with the HDAC inhibitor vorinostat results in synergistic antiproliferative activity against KRAS-mutant CRC cell lines in vitro. In vivo, the combination showed additive effects that were associated with metabolic changes in phospholipid turnover, but not on FDG-PET, indicating that the former is a more sensitive endpoint of the combination effects.

miRNA signature associated with outcome of gastric cancer patients following chemotherapy

Background

Identification of patients who likely will or will not benefit from cytotoxic chemotherapy through the use of biomarkers could greatly improve clinical management by better defining appropriate treatment options for patients. microRNAs may be potentially useful biomarkers that help guide individualized therapy for cancer because microRNA expression is dysregulated in cancer. In order to identify miRNA signatures for gastric cancer and for predicting clinical resistance to cisplatin/fluorouracil (CF) chemotherapy, a comprehensive miRNA microarray analysis was performed using endoscopic biopsy samples.

Methods

Biopsy samples were collected prior to chemotherapy from 90 gastric cancer patients treated with CF and from 34 healthy volunteers. At the time of disease progression, post-treatment samples were additionally collected from 8 clinical responders. miRNA expression was determined using a custom-designed Agilent microarray. In order to identify a miRNA signature for chemotherapy resistance, we correlated miRNA expression levels with the time to progression (TTP) of disease after CF therapy.

Results

A miRNA signature distinguishing gastric cancer from normal stomach epithelium was identified. 30 miRNAs were significantly inversely correlated with TTP whereas 28 miRNAs were significantly positively correlated with TTP of 82 cancer patients (P<0.05). Prominent among the upregulated miRNAs associated with chemosensitivity were miRNAs known to regulate apoptosis, including let-7g, miR-342, miR-16, miR-181, miR-1, and miR-34. When this 58-miRNA predictor was applied to a separate set of pre- and post-treatment tumor samples from the 8 clinical responders, all of the 8 pre-treatment samples were correctly predicted as low-risk, whereas samples from the post-treatment tumors that developed chemoresistance were predicted to be in the high-risk category by the 58 miRNA signature, suggesting that selection for the expression of these miRNAs occurred as chemoresistance arose.

Conclusions

We have identified 1) a miRNA expression signature that distinguishes gastric cancer from normal stomach epithelium from healthy volunteers, and 2) a chemoreresistance miRNA expression signature that is correlated with TTP after CF therapy. The chemoresistance miRNA expression signature includes several miRNAs previously shown to regulate apoptosis in vitro, and warrants further validation.

Modeling the transcriptional consequences of epidermal growth factor receptor ablation in Ras-initiated squamous cancer

PURPOSE

Epidermal growth factor receptor (EGFR)-targeted therapy is in clinical use to treat squamous cell carcinoma of the head and neck and other cancers of lining epithelium. RAS mutations in these tumors are a negative prognostic factor for response, and skin inflammation is an adverse reaction to therapy. We investigated transcriptional and biochemical changes that could account for the confounding effects of RAS activation and inflammation in a squamous tissue.

EXPERIMENTAL DESIGN

We carried out gene expression profiling on oncogenic Ras-transformed and wild-type mouse and human keratinocytes with EGFR ablated chronically by genetic deletion or acutely by drug treatment and followed leads provided by pathway analysis with biochemical studies.

RESULTS

We identified a 25-gene signature specific to the Ras-EGFR ablation interaction and a distinct 19-gene EGFR ablation signature on normal keratinocytes. EGFR ablation in the context of wild-type Ras reduces ontologies favoring cell-cycle control and transcription, whereas oncogenic Ras enriches ontologies for ion channels and membrane transporters, particularly focused on calcium homeostasis. Ontologies between chronic EGFR ablation and acute pharmacologic ablation were unique, both with and without Ras activation. p38α is activated in response to abrogation of EGFR signaling under conditions of Ras activation in both mouse and human keratinocytes and in RAS-transformed tumor orthografts of EGFR-ablated mouse keratinocytes. EGFR ablation in the absence of oncogenic Ras revealed Erk and interleukin-1β-related pathways.

CONCLUSION

These findings reveal unrecognized interactions between Ras and EGFR signaling in squamous tumor cells that could influence the therapeutic response to EGFR ablation therapy.

Biologically targeted cancer therapy and marginal benefits: are we making too much of too little or are we achieving too little by giving too much?

We describe the development and approval of biologically targeted agents in the clinic through examples chosen from the experience with inhibitors of the epidermal growth factor (EGF) and VEGF pathways. Despite extensive biological rationale for the use of these classes of molecules, marginal clinical benefits have been observed in broad patient populations, and the agents have entered into general clinical practice. We discuss why this situation is unsatisfactory because marginal general benefit may often be at the expense of toxicity to nonbenefiting or even harmed patients. Finally, we point out that emerging technologies bring the promise of allowing the identification of patients who might potentially benefit from a therapy. However, development of this technology will not move forward without broader recognition of its need by the range of stakeholders, including patients, advocates, academic and private oncologists, drug sponsors, and those who develop drugs and diagnostic tests.

Three-gene predictor of clinical outcome for gastric cancer patients treated with chemotherapy

To identify transcriptional profiles predictive of the clinical benefit of cisplatin and fluorouracil (CF) chemotherapy to gastric cancer patients, endoscopic biopsy samples from 96 CF-treated metastatic gastric cancer patients were prospectively collected before therapy and analyzed using high-throughput transcriptional profiling and array comparative genomic hybridization. Transcriptional profiling identified 917 genes that are correlated with poor patient survival after CF at P<0.05 (poor prognosis signature), in which protein synthesis and DNA replication/recombination/repair functional categories are enriched. A survival risk predictor was then constructed using genes, which are included in the poor prognosis signature and are contained within identified genomic amplicons. The combined expression of three genes—MYC, EGFR and FGFR2—was an independent predictor for overall survival of 27 CF-treated patients in the validation set (adjusted P=0.017), and also for survival of 40 chemotherapy-treated gastric cancer patients in a published data set (adjusted P=0.026). Thus, combined expression of MYC, EGFR and FGFR2 is predictive of poor survival in CF-treated metastatic gastric cancer patients.

KRAS mutation detection and prognostic potential in sporadic colorectal cancer using high-resolution melting analysis

BACKGROUND

The development of targeted therapies has created a pressing clinical need for molecular characterisation of cancers. In this retrospective study, high-resolution melting analysis (HRMA) was validated and implemented for screening of 164 colorectal cancer (CRC) patients to detect KRAS hot-spot mutations and to evaluate its prognostic value. Direct sequencing was used to confirm and characterise HRMA results.

METHODS

After establishing its sensitivity, HRMA was validated on seven cell lines and inter- and intra-variation were analysed. The prognostic value of KRAS mutations in CRC was evaluated using survival analysis.

RESULTS

HRMA revealed abnormal melting patterns in 34.1% CRC samples. Kaplan-Meier survival curves revealed a significantly shorter overall (OS) and disease-free survival (DFS) for CRC patients harbouring a KRAS mutation. In the Cox regression analysis, only when colon and rectal cancer were analysed separately, KRAS mutation was a negative predictor for OS in patients with rectal cancer and DFS in those with stage II colon cancer.

CONCLUSIONS

HRMA was found to be a valid screening method for KRAS mutation detection. The KRAS mutation came forward as a negative predictive factor for OS in patients with rectal cancer and for DFS in stage II colon cancer patients.

Co-expression of nuclear and cytoplasmic HMGB1 is inversely associated with infiltration of CD45RO+ T cells and prognosis in patients with stage IIIB colon cancer

Background

The intratumoral infiltration of T cells, especially memory T cells, is associated with a favorable prognosis in early colorectal cancers. However, the mechanism underlying this process remains elusive. This study examined whether high-mobility group box 1 (HMGB1), a damage-associated molecular pattern (DAMP) molecule, is involved in the infiltration of T cells and disease progression in locally advanced colon cancer.

Methods

Seventy-two cases of pathologically-confirmed specimens were obtained from patients with stage IIIB (T3N1M0) colon cancer who underwent radical resection between January 1999 and May 2002 at the Cancer Center of Sun Yat-Sen University. The density of tumor-infiltrating lymphocytes (TILs) within the tumor tissue and the expression of HMGB1 in the cancer cells were examined via immunohistochemical analysis. The phenotype of CD45RO+ cells was confirmed using a flow cytometric assay. The association between HMGB1 expression, the density of TILs, and the 5-year survival rate were analyzed.

Results

The density of CD45RO+ T cells within the tumor was independently prognostic, although a higher density of CD3+ T cells was also associated with a favorable prognosis. More importantly, the expression of HMGB1 was observed in both the nucleus and the cytoplasm (co-expression pattern) in a subset of colon cancer tissues, whereas nuclear-only expression of HMGB1 (nuclear expression pattern) existed in most of the cancer tissues and normal mucosa. The co-expression pattern of HMGB1 in colon cancer cells was inversely associated with the infiltration of both CD3+ and CD45RO+ T cells and 5-year survival rates.

Conclusions

This study revealed that the co-expression of HMGB1 is inversely associated with the infiltration of CD45RO+ T cells and prognosis in patients with stage IIIB colon cancer, indicating that the distribution patterns of HMGB1 might contribute to the progression of colon cancer via modulation of the local immune response.

Targeted immunotherapy for colorectal cancer: monoclonal antibodies and immunotoxins

Colorectal cancer (CRC) is a major health concern worldwide. It is the third most frequently diagnosed cancer and the second leading cause of cancer death. There currently are a number of treatment options for CRC, however many of them have failed to demonstrate desired therapeutic benefit. Therefore, significant efforts are being directed towards the development of new biological therapies with improved efficacy. Immunotherapy is an emerging treatment modality for a variety of cancers. Several promising treatments have already been approved by the US FDA and are being tested in clinical trials. Antibodies have been proved to be useful in cancer therapy due to their ability to recognize tumor-associated antigens expressed at higher density on malignant cells in comparison with those that are normal. Antibodies can be used as a single therapy or in combination with other therapies. A large variety of monoclonal antibodies have been developed. However, only a very few are able to kill a sufficient number of malignant cells and cause tumor regression. Hence, it is often necessary to arm the antibody with a cytotoxic agent to enhance the efficacy of the anti-tumor activity. This review provides a brief overview of some of the current agents being employed in targeted immunotherapy for CRC.

Cetuximab-based therapy for metastatic colorectal cancer: a meta-analysis of the effect of K-ras mutations

BACKGROUND

Cetuximab has a favorable effect on patients with metastatic colorectal cancer harboring wild K-ras gene. This meta-analysis was planned to quantify the benefit.

METHODS

A meta-analysis of clinical studies that have used cetuximab-based therapy (CBT) for patients with known K-ras status.

RESULTS

There were four randomized studies (RS) that compared CBT versus non-cetuximab control (NCC) in 2,292 patients, and six non-randomized studies (NRS) included patients received cetuximab after failure of prior chemotherapy (411 patients). Patients in RS with wild K-ras tumor gained more benefit from CBT vs. NCC. For response rate (RR), the odds ratio was 2.10 (p = 0.0002), while the hazard ratio (HR) for progression-free survival (PFS) was 0.64 (p = 0.04). On the other hand, CBT was associated with an adverse effect on RR and no effect on PFS in mutated K-ras. In all patients who received CBT in RS and NRS, those with wild vs. mutated K-ras demonstrated higher RR (odds ratio 3.72; p < 0.0001). Compared with NCC in three RS, CBT showed significant overall survival (OS) advantage in patients with wild K-ras (HR = 0.68; p = 0.01).

CONCLUSIONS

The significant clinical benefit of CBT concerning RR, PFS, and OS was restricted to patients with wild-type K-ras. There is a need to better define potential responders to CBT.

Identification of expression signatures predictive of sensitivity to the Bcl-2 family member inhibitor ABT-263 in small cell lung carcinoma and leukemia/lymphoma cell lines

ABT-263 inhibits the antiapoptotic proteins Bcl-2, Bcl-x(L), and Bcl-w and has single-agent efficacy in numerous small cell lung carcinoma (SCLC) and leukemia/lymphoma cell lines in vitro and in vivo. It is currently in clinical trials for treating patients with SCLC and various leukemia/lymphomas. Identification of predictive markers for response will benefit the clinical development of ABT-263. We identified the expression of Bcl-2 family genes that correlated best with sensitivity to ABT-263 in a panel of 36 SCLC and 31 leukemia/lymphoma cell lines. In cells sensitive to ABT-263, expression of Bcl-2 and Noxa is elevated, whereas expression of Mcl-1 is higher in resistant cells. We also examined global expression differences to identify gene signature sets that correlated with sensitivity to ABT-263 to generate optimal signature sets predictive of sensitivity to ABT-263. Independent cell lines were used to verify the predictive power of the gene sets and to refine the optimal gene signatures. When comparing normal lung tissue and SCLC primary tumors, the expression pattern of these genes in the tumor tissue is most similar to sensitive SCLC lines, whereas normal tissue is most similar to resistant SCLC lines. Most of the genes identified using global expression patterns are related to the apoptotic pathway; however, all but Bcl-rambo are distinct from the Bcl-2 family. This study leverages global expression data to identify key gene expression patterns for sensitivity to ABT-263 in SCLC and leukemia/lymphoma and may provide guidance in the selection of patients in future clinical trials.

Molecular mechanisms of resistance to cetuximab and panitumumab in colorectal cancer

Personalized cancer medicine based on the genetic milieu of individual colorectal tumors has long been postulated, but until recently this concept was not supported by clinical evidence. The advent of the epidermal growth factor receptor (EGFR) -targeted monoclonal antibodies cetuximab and panitumumab has paved the way to the individualized treatment of metastatic colorectal cancer (mCRC). Here we discuss the evidence that mCRCs respond differently to EGFR-targeted agents and that the tumor-specific response has a genetic basis. We outline how, from the initial observation that cetuximab or panitumumab as monotherapy is effective only in 10% to 20% of mCRCs, knowledge has being gained on the molecular mechanisms underlying primary resistance to these agents. The role of oncogenic activation of EGFR downstream effectors such as KRAS, BRAF, PIK3CA, and PTEN on response to therapy is discussed. We suggest that CRCs lacking oncogenic alterations in these four genes have the highest probability of response to anti-EGFR therapies and are defined as "quadruple negative." The rapid and effective translation of these findings into predictive biomarkers to couple EGFR-targeted antibodies to the patients who benefit from them is presented as a paradigm of modern clinical oncology. Finally, unresolved questions such as understanding the molecular basis of response as well the mechanisms of secondary resistance are presented as the future fundamental goals in this research field.