Activating KRAS mutations and overexpression of epidermal growth factor receptor as independent predictors in metastatic colorectal cancer patients treated with cetuximab

Integrating contextual miRNA and protein signatures for diagnostic and treatment decisions in cancer

The promise of personalized medicine is highly dependent on the identification of biomarkers that inform diagnostic decisions and treatment options, as well as on the accurate, rapid and cost-effective detection and interpretation of these biomarkers. miRNAs, which are short noncoding regulatory RNAs, are rapidly emerging as a novel class of biomarkers with a unique set of biological and chemical properties that makes them very appealing candidates for theranostic applications in cancer. Since the utility of some protein-encoding gene biomarkers is already exploited in routine clinical practice, it will be important to identify areas in which miRNAs provide complementary or superior information to these existing (and other translational) biomarkers to enhance the diagnostic, prognostic and predictive power of molecular characterization of tumors. In this article, the challenges and opportunities for integration of miRNA-based assays in the clinical toolkit to improve care and management of patients afflicted with solid tumors will be discussed.

KRAS mutational status of endoscopic biopsies matches resection specimens

Aims

This study was performed to determine systematically whether KRAS mutational analysis in biopsy tissue is a reliable indicator of KRAS status in subsequent corresponding resection specimens.

Methods

30 colorectal cancer (CRC) patients with biopsy and corresponding subsequent surgical resection specimens were studied. KRAS mutational analysis was performed on each biopsy sample as well as two separate samples from each resection specimen by PCR and Sanger sequencing.

Results

Overall, KRAS mutations were identified in 12/30 (40%) of the tumours. There was 100% correlation between biopsy and resection specimens regarding the presence or absence of KRAS mutations. In fact, the same point mutation was identified in both biopsy and corresponding resection specimens in 12/12 (100%) cases. In addition, in two cases, there were two different point mutations detected within the same biopsy specimen.

Conclusion

This study shows perfect correlation between KRAS mutation status in biopsy and resection specimens from an individual patient, and suggests that biopsy material is adequate for KRAS mutational analysis in CRC patients.

Involvement of store-operated calcium signaling in EGF-mediated COX-2 gene activation in cancer cells

Growing evidence shows that chronic inflammation drives the progression of colorectal cancer (CRC). Cyclooxygenase-2 (COX-2) is one of the most important inflammatory genes involved in solid tumor metastasis. Epidermal growth factor receptor (EGFR) also plays a key role in cancer cell development. We compared the expression levels of EGFR and COX-2 between tumor and normal tissues from 20 CRC patients and studied the molecular mechanism of EGFR-mediated COX-2 gene expression in cancer cells. Our results indicated that COX-2 expression was markedly increased after EGF stimulation. COX-2 promoter analysis indicated the involvement of cyclic AMP-responsive element (CRE) and nuclear factor of activated T cells/nuclear factor interleukin-6 (NFAT/NF-IL6)-binding sites in EGF-mediated signaling pathways. Furthermore, EGF-mediated COX-2 activation was prevented by 2-aminoethoxydiphenyl borate (2-APB), a store-operated Ca(2+) channel inhibitor. Transfection of siRNA against ORAI1 or STIM1, the key regulators of store-operated Ca(2+) channels, showed significant inhibitory effects on EGF-mediated COX-2 expression. In conclusion, store-operated Ca(2+) entry is involved in the activation of transcription factors (CREB/NFAT) that are responsible for delivering EGF-mediated signals to evoke inflammatory cascades and is eventually related to CRC tumorigenesis.

Molecular targeted agents for gastric and gastroesophageal junction cancer

Despite recent improvements in surgical techniques and chemotherapy, advanced cancers of the stomach and gastroesophageal junction (GEJ) continue to have poor clinical outcomes. However, molecules intimately related to cancer cell proliferation, invasion, and metastasis have been studied as candidates for molecular targeted agents. Target molecules, such as the epidermal growth factor receptor, vascular endothelial growth factor receptor, and P13k/Akt/mTor pathway, as well as the insulin-like growth factor receptor, c-Met pathways, fibroblast growth factor receptor, and other pathways are considered to be promising candidates for molecular targeted therapy for gastric and GEJ cancer. In this review we focus on the recent developments in targeting relevant pathways in these types of cancer.

Cetuximab plus FOLFIRINOX (ERBIRINOX) as first-line treatment for unresectable metastatic colorectal cancer: a phase II trial

BACKGROUND

Triplet chemotherapy has demonstrated manageable toxicities and a favorable response rate. The addition of cetuximab to chemotherapy can increase treatment efficacy. We evaluated the efficacy and safety of cetuximab plus 5-fluorouracil, leucovorin, irinotecan, and oxaliplatin (FOLFIRINOX), the ERBIRINOX regimen, as first-line treatment in patients with unresectable metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

In a phase II study, treatment consisted of weekly cetuximab plus biweekly. Treatment was continued for a maximum of 12 cycles and tumor response was evaluated every four cycles. The primary efficacy criterion was the complete response (CR) rate.

RESULTS

From April 2006 to April 2008, 42 patients were enrolled. The median age was 60 years (range, 32-76 years). The median duration of treatment was 5.2 months (range, 0.7-8.5 months), and a median of nine cycles was given per patient (range, 1-12 cycles). Five patients (11.9%) showed a CR, with a median duration of 23.1 months (95% confidence interval [CI], 10.8-39.7 months). The objective response rate was 80.9% (95% CI, 65.9%-91.4%). The median overall and progression-free survival times were 24.7 months (95% CI, 22.6 months to not reached) and 9.5 months (95% CI, 7.6-10.4 months), respectively. The most frequent grade 3-4 adverse events were diarrhea (52%), neutropenia (38%), and asthenia (32%).

CONCLUSION

The ERBIRINOX regimen appears to be effective and feasible in first-line treatment of mCRC patients. These promising results led us to initiate a multicenter, randomized, phase II trial ([Research Partnership for Digestive Oncology] PRODIGE 14) in patients with potentially resectable mCRC.

An EGFR inhibitor enhances the efficacy of SN38, an active metabolite of irinotecan, in SN38-refractory gastric carcinoma cells

BACKGROUND

Acquired drug resistance to irinotecan is one of the significant obstacles in the treatment of advanced gastric cancer. This study was performed to clarify the effect of epidermal growth factor receptor (EGFR) inhibitors in combination with SN38, an active metabolite of irinotecan, on the proliferation of irinotecan-refractory gastric cancer.

METHODS

Two irinotecan-resistant gastric cancer cell lines, OCUM-2M/SN38 and OCUM-8/SN38 were, respectively, established by stepwise exposure to SN38 from the parent gastric cancer cell lines OCUM-2M and OCUM-8. The combination effects of two EGFR inhibitors, gefitinib and lapatinib, with SN38 on proliferation, apoptosis, and cell cycle on gastric cancer cells were examined.

RESULTS

Gefitinib or lapatinib showed synergistic anti-tumour effects against OCUM-2M/SN38 and OCUM-8/SN38 cells when used in combination with SN38, but not against OCUM-2M or OCUM-8 cells. SN38 increased the expression of EGFR and HER2 in OCUM-2M/SN38 and OCUM-8/SN38 cells. The combination of an EGFR inhibitor and SN38 significantly increased the levels of apoptosis-related molecules, caspase-6, p53, and DAPK-2, and resulted in the induction of apoptosis of irinotecan-resistant cells. The EGFR inhibitors increased the S-phase and decreased the UGT1A1 and ABCG expression in irinotecan-resistant cells. The SN38 plus Lapatinib group more effectively suppressed in vivo tumour growth by OCUM-2M/SN38 cells than either alone group.

CONCLUSION

The combination treatment with an EGFR inhibitor and irinotecan might produce synergistic anti-tumour effects for irinotecan-refractory gastric cancer cells. The regulation of SN38 metabolism-related genes and cell cycle by EGFR inhibitors might be responsible for the synergism.

Prospective analysis of KRAS wild-type patients with metastatic colorectal cancer using cetuximab plus FOLFIRI or FOLFOX4 treatment regimens

Cetuximab, a monoclonal antibody targeting epidermal growth factor receptor, has proven to be efficient in the treatment of metastatic colorectal cancer. We made a prospective study of the efficacy and toxicities of cetuximab-combination first-line (FOLFOX4) versus second/third-line (FOLFIRI) chemotherapy in 98 KRAS wild-type patients who had metastatic colorectal cancer. Wild-type KRAS had been identified by direct sequencing. Associations between clinical response/progression-free survival/overall survival/toxicities and cetuximab-combination chemotherapy timing were evaluated. The overall response rate was significantly higher for first-line treatment than for second/third-line treatment (relative risk = 1.707, 95% confidence interval = 1.121-2.598). Both progression-free survival and overall survival indicated significantly longer survival of first-line treatment than second/third-line treatment patients. This study is a validation of a molecular analysis of KRAS wild-type status for the prediction of response to cetuximab-combination chemotherapy for metastatic colorectal cancer patients; its predictive role was less prominent in the second/third-line than in the first-line treatment patients.

An Update on the Biology of RAS/RAF Mutations in Colorectal Cancer

Deaths caused by colorectal cancer (CRC) are among the leading causes of cancer-related death in the United States and around the world. Approximately 150,000 Americans are diagnosed with CRC each year and around 50,000 will die from it. Mutations in many key genes have been identified that are important to the pathogenesis of CRC. Among the genes mutated in CRC, RAS and RAF mutations are common events. Both RAS and RAF are critical mediators of the mitogen-activated protein kinase (MAPK) pathway that is involved in regulating cellular homeostasis, including proliferation, survival, and differentiation. In this review, we provide a historical perspective and update on RAS/RAF mutations as related to colorectal cancer. Additionally, we will review recent mouse models of RAS and RAF mutations that have an impact on CRC research.

Biomarkers for cetuximab-based neoadjuvant radiochemotherapy in locally advanced rectal cancer

PURPOSE

Phase II trials in locally advanced rectal cancer have shown that cetuximab-based neoadjuvant radiochemotherapy is feasible but without an improvement in complete pathologic response rates. Our goal was to identify patients who would benefit from cetuximab-based neoadjuvant chemoradiation measuring gene expression levels of proteins involved in tumor growth [endothelial growth factor receptor (EGFR)], angiogenesis [VEGF, VEGF receptors 1 and 2 (VEGFR1, VEGFR2)], DNA repair [excision repair cross-complementing 1 (ERCC1)], and drug metabolism [thymidylate synthetase (TS)]. We also determined mutation status of KRAS and BRAF.

EXPERIMENTAL DESIGN

This study was carried out on 130 patients with locally advanced rectal cancer who were enrolled in 4 different phase II clinical trials, using cetuximab-based chemoradiation. Tumor tissues were obtained before neoadjuvant and at surgical therapy. After microdissection, intratumoral gene expression levels and KRAS/BRAF mutation status were analyzed.

RESULTS

A significant decrease of TS, VEGFR1, and VEGFR2 gene expression was seen following neoadjuvant therapy (P < 0.03). High pretreatment VEGF gene expression levels were associated with nonresponse (P = 0.070). KRAS mutations were found in 42% and mutant KRAS (KRAS mt) was significantly associated with pathologic nonresponse (P = 0.037). In patients with wild-type KRAS (KRAS wt), low EGFR was significantly associated with higher nonresponse and VEGF mRNA expressions were associated with complete pathologic response (P = 0.012; P = 0.06). KRAS transversion (KRAS tv) was associated with tumor regression: nonresponse was more common in patients with KRAS tv than with KRAS wt (P = 0.007). BRAF V600E mutations were not detected in any of the patients.

CONCLUSION

This study suggests that pretreatment intratumoral EGFR and VEGF mRNA expression levels as well as KRAS mutation status are predictive markers of pathologic response to neoadjuvant cetuximab-based chemoradiation in locally advanced rectal cancer.

Genetic tumor profiling and genetically targeted cancer therapy

OBJECTIVES

To discuss how understanding and manipulation of tumor genetics information and technology shapes cancer care today and what changes might be expected in the near future.

DATA SOURCES

Published articles, web resources, clinical practice.

CONCLUSIONS

Advances in our understanding of genes and their regulation provide a promise of more personalized cancer care, allowing selection of the most safe and effective therapy in an individual situation.

IMPLICATIONS FOR NURSING PRACTICE

Rapid progress in the technology of tumor profiling and targeted cancer therapies challenges nurses to keep up-to-date to provide quality patient education and care.

Rational engineering of antibody therapeutics targeting multiple oncogene pathways

Monoclonal antibodies have significantly advanced our ability to treat cancer, yet clinical studies have shown that many patients do not adequately respond to monospecific therapy. This is in part due to the multifactorial nature of the disease, where tumors rely on multiple and often redundant pathways for proliferation. Bi- or multi- specific antibodies capable of blocking multiple growth and survival pathways at once have a potential to better meet the challenge of blocking cancer growth, and indeed many of them are advancing in clinical development. ( 1) However, bispecific antibodies present significant design challenges mostly due to the increased number of variables to consider. In this perspective we describe an innovative integrated approach to the discovery of bispecific antibodies with optimal molecular properties, such as affinity, avidity, molecular format and stability. This approach combines simulations of potential inhibitors using mechanistic models of the disease-relevant biological system to reveal optimal inhibitor characteristics with antibody engineering techniques that yield manufacturable therapeutics with robust pharmaceutical properties. We illustrate how challenges of meeting the optimal design criteria and chemistry, manufacturing and control concerns can be addressed simultaneously in the context of an accelerated therapeutic design cycle. Finally, to demonstrate how this rational approach can be applied, we present a case study where the insights from mechanistic modeling were used to guide the engineering of an IgG-like bispecific antibody.

EGFR related mutational status and association to clinical outcome of third-line cetuximab-irinotecan in metastatic colorectal cancer

Background

As supplement to KRAS mutational analysis, BRAF and PIK3CA mutations as well as expression of PTEN may account for additional non-responders to anti-EGFR-MoAbs treatment. The aim of the present study was to investigate the utility as biomarkers of these mutations in a uniform cohort of patients with metastatic colorectal cancer treated with third-line cetuximab/irinotecan.

Methods

One-hundred-and-seven patients were prospectively included in the study. Mutational analyses of KRAS, BRAF and PIK3CA were performed on DNA from confirmed malignant tissue using commercially available kits. Loss of PTEN and EGFR was assessed by immunohistochemistry.

Results

DNA was available in 94 patients. The frequency of KRAS, BRAF and PIK3CA mutations were 44%, 3% and 14%, respectively. All were non-responders. EGF receptor status by IHC and loss of PTEN failed to show any clinical importance. KRAS and BRAF were mutually exclusive. Supplementing KRAS analysis with BRAF and PIK3CA indentified additional 11% of non-responders. Patient with any mutation had a high risk of early progression, whereas triple-negative status implied a response rate (RR) of 41% (p < 0.001), a disease control (DC) rate of 73% (p < 001), and a significantly higher PFS of 7.7(5.1-8.6 95%CI) versus 2.3 months (2.1-3.695%CI) (p < 0.000).

Conclusion

Triple-negative status implied a clear benefit from treatment, and we suggest that patient selection for third-line combination therapy with cetuximab/irinotecan could be based on triple mutational testing.

The effect of cytotoxic chemotherapy on the risk of high-grade acneiform rash to cetuximab in cancer patients: a meta-analysis

BACKGROUND

The effect of chemotherapy on the risk of cetuximab-induced acneiform rash is unknown. We carried out a systematic review and meta-analysis of published studies to quantify the incidence and risk of high-grade acneiform rash with combination therapy.

METHODS

Relevant studies were identified from PubMed database, abstracts presented at the American Society of Clinical Oncology conferences, and Web of Science. Incidence of acneiform rash to cetuximab monotherapy was estimated based on updated data from our previously published meta-analysis. Incidence, relative risk (RR), and 95% confidence intervals (CIs) were calculated based on the heterogeneity of included studies.

RESULTS

A total of 5333 patients from nine trials were included in the analysis. The incidence of high-grade acneiform rash was significantly increased in patients receiving combination treatment (12.8%, 95% CI 9.1% to 17.7%) as compared with cetuximab monotherapy (6.3%, 95% CI 3.7% to 10.5%), with a risk ratio of 2.03 (95% CI 1.52-2.71, P < 0.01). Cetuximab significantly increased the risk of high-grade rash in patients receiving combination therapy (RR = 37.7, 95% CI 17.8-80.0, P < 0.001).

CONCLUSIONS

Addition of cytotoxic chemotherapy to cetuximab significantly increases the risk of high-grade acneiform rash compared with cetuximab monotherapy. This emphasizes the need for effective management strategies.

Management of stage IV rectal cancer: Palliative options

Approximately 30% of patients with rectal cancer present with metastatic disease. Many of these patients have symptoms of bleeding or obstruction. Several treatment options are available to deal with the various complications that may afflict these patients. Endorectal stenting, laser ablation, and operative resection are a few of the options available to the patient with a malignant large bowel obstruction. A thorough understanding of treatment options will ensure the patient is offered the most effective therapy with the least amount of associated morbidity. In this review, we describe various options for palliation of symptoms in patients with metastatic rectal cancer. Additionally, we briefly discuss treatment for asymptomatic patients with metastatic disease.

Oncogenic mutations in gastric cancer with microsatellite instability

AIM

Mitogen-activated protein kinase (MAPK) cascade and phosphatidylinositol 3-kinase (PI3K) survival pathways are frequently activated in the progression of gastrointestinal malignancies. In this study, we aimed to determine the frequency of gene mutations in members of these pathways--Epithelial Growth Factor Receptor (EGFR), KRAS, BRAF, PIK3CA and MLK3 in a series of 63 gastric carcinomas with high levels of microsatellite instability (MSI).

METHODS

Gene mutation analysis was performed by PCR amplification followed by direct sequencing. In selected tumour cases, EGFR expression was evaluated by immunohistochemistry. Association studies between molecular data and clinicopathologic characteristics were performed.

RESULTS

Mutations in EGFR (3'-untranslated region [UTR] polyA repeat), KRAS, PIK3CA and MLK3 genes occurred in 30 (47.6%), 11 (17.5%), 9 (14.3%) and 2 (3.2%) of the MSI gastric cancer (GC) cases, respectively. No BRAF or EGFR hotspot mutations were identified. Overall, mutations in at least one of these genes were found in 55.6% (35/63) of gastric carcinomas. From those mutant cases 40.0% (14/35) of them had concomitant gene mutations, always involving EGFR polyA deletions. Interestingly, we observed significant associations between oncogenic mutations and female gender (p = 0.046) old age of diagnosis (p = 0.001) and intestinal subtype (p = 0.043).

CONCLUSION

Our results show that MSI gastric carcinoma frequently shows activation of EGFR-MAPK and PI3K pathways. Within all alterations found, deletions of the A13 repeats of EGFR were common, suggesting this molecular event as an important biomarker for stratification of GC patients for treatment with EGFR inhibitors.

Recent advances in detection of k-ras gene mutations and targeted therapy of colorectal cancer

Numerous studies have shown that anti-epidermal growth factor receptor (EGFR) monoclonal antibodies are effective in the treatment of colorectal cancer patients with the wild-type k-ras gene. The k-ras gene encodes a G-protein that functions downstream of EGFR signaling. Since k-ras mutations result in abnormal activation of the EGFR signaling pathway, anti-EGFR monoclonal antibody treatment is ineffective for patients with k-ras mutations. Therefore, k-ras mutation analysis is very important for targeted therapy of patients with colorectal cancer. This paper gives an overview of the recent advances in detection of k-ras gene mutations and targeted therapy of colorectal cancer.

Personalized medicine and oncology practice guidelines: a case study of contemporary biomarkers in colorectal cancer

Predictive and prognostic biomarkers offer a potential means to personalize cancer medicine, although many reach the market-place before they have been validated, and their adoption is often hindered by variable clinical evidence. Because of this variability in supporting evidence, clinical practice guidelines formulated by panels of subspecialty experts may be particularly important in guiding stakeholders' acceptance and use of new personalized medicine biomarker tests and other nascent technologies. This article provides a structured review of the clinical evidence supporting 4 contemporary biomarker tests in colorectal cancer: K-ras and B-raf mutation analyses, mismatch repair protein testing, and the Oncotype DX Colon Cancer Assay. All 4 tests have been evaluated for guideline inclusion by the NCCN Guidelines Panel for Colon Cancer. This case study shows significant variability in the level of clinical evidence associated with these tests. In the cases of B-raf and mismatch repair protein testing, the available evidence is also inconsistent as it pertains to the specific NCCN Guideline recommendation. Based on this uncertainty in the evidence base, the authors conclude that expert clinical judgment, experience, and consensus may be more heavily weighted than published clinical trial data in the evaluation of new personalized medicine biomarker tests. Potential implications of this conclusion and future directions for research are discussed.

KRAS mutational analysis for colorectal cancer. Application: pharmacogenomic

KRAS mutational analysis is a genetic test used in clinical practice for determining the status of the KRAS gene (wild type or mutant) in tumors from patients with metastatic colorectal cancer (CRC). Persons whose tumors are wild type may respond to therapies cetuximab (Erbitux) or panitumumab (Vectibix).