Long-Term 5-Year Response to Pembrolizumab, Bevacizumab, and Capecitabine Regimen in a Metastatic Colon Cancer Patient with MSI-High and KRAS Mutation: Case Report

With an estimated 1.88 million new cases and 0.92 million deaths in 2020, colorectal cancer accounts for nearly one-tenth of all new cancer and cancer-related deaths worldwide. Nearly half of the patients of colorectal cancer are diagnosed with metastatic or inoperable disease with a very dismal 5-year survival rate. Chemotherapy, targeted therapy, and immunotherapy have been used to treat metastatic disease, either alone or in combination. We present a case of recurrent metastatic colon carcinoma with KRAS exon 2 mutation and high microsatellite instability that was treated with a combination regimen of bevacizumab, capecitabine oral chemotherapy, and pembrolizumab immunotherapy. At nearly 5 years of treatment, the patient is alive with good performance status and improved quality of life owing to a favorable response to the molecular profiling-based treatment approach.

Pathological Features and Prognostication in Colorectal Cancer

The prognostication of colorectal cancer (CRC) has traditionally relied on staging as defined by the Union for International Cancer Control (UICC) and American Joint Committee on Cancer (AJCC) TNM staging classifications. However, clinically, there appears to be differences in survival patterns independent of stage, suggesting a complex interaction of stage, pathological features, and biomarkers playing a role in guiding prognosis, risk stratification, and guiding neoadjuvant and adjuvant therapies. Histological features such as tumour budding, perineural invasion, apical lymph node involvement, lymph node yield, lymph node ratio, and molecular features such as MSI, KRAS, BRAF, and CDX2 may assist in prognostication and optimising adjuvant treatment. This study provides a comprehensive review of the pathological features and biomarkers that are important in the prognostication and treatment of CRC. We review the importance of pathological features and biomarkers that may be important in colorectal cancer based on the current evidence in the literature.

Bevacizumab and erlotinib versus bevacizumab for colorectal cancer treatment: systematic review and meta-analysis

Background Improving the survival of patients diagnosed with metastatic colorectal cancer requires the use of chemotherapy to be managed with minimum adverse effects. Randomized control trials (RCTs) have shown promising results with a combination of bevacizumab and erlotinib to block two important tumor growth pathways, namely vascular endothelial growth factor and epidermal growth factor receptor. Aim of the Review We aimed to examine the efficacy and safety of the combination of bevacizumab and erlotinib with bevacizumab alone in the maintenance treatment of metastatic colorectal cancer, by examining PFS, OS, overall response rate (ORR), and toxicity. This study performed a systematic review meta-analysis using existing randomized clinical trial. Methods Randomized controlled trials were systematically reviewed from PubMed, Cochrane library, SCOPUS, CRD, and Google scholar databases. After evaluating the quality of studies through the Cochrane checklist, data of the relevant studies were extracted. This meta-analysis included outcomes of overall survival, progression-free survival of the disease through the hazard ratio, and the upper and lower confidence intervals for the third and fourth degree side effects of relative risk. To perform the meta-analysis for both types of survival, two fixed and random effect models were used. Results A total of three trials, providing data of 682 patients who received maintenance treatment, were included in this meta-analysis. Conclusion The combination of bevacizumab and erlotinib significantly increased the overall survival compared to using bevacizumab alone [HR = 0.78, 95% CI 0.66-0.93]. This combination, effectively increased progression-free survival [HR = 0.81, 95% CI 0.7-0.93] too. The side effects of diarrhea and grade III rash were more frequent in the group administered bevacizumab plus erlotinib. The combination of bevacizumab and erlotinib, in the maintenance treatment of metastatic colorectal cancer, significantly improved the overall survival and progression-free survival of patients, and the resulting side effects were easily treatable.

Incidence and risk of hypertension associated with vascular endothelial growth factor receptor tyrosine kinase inhibitors in cancer patients: a comprehensive network meta-analysis of 72 randomized controlled trials involving 30013 patients

Background

Tyrosine kinase inhibitors (TKIs) have been developed during the last decade that target the vascular endothelial growth factor receptor (VEGFR) are currently being evaluated as treatments for malignant tumors. The increased application of VEGFR-TKIs means that the probability of hypertension is a serious concern. However, the reported incidence varies markedly between clinical trials. Here, we undertook an up-to-date, comprehensive meta-analysis on clinical works to build the incidence of hypertension along with VEGFR-TKIs. The goal was to understand better of the overall venture of cancer patients’ hypertension treated with these drugs.

Methods

Databases (EMBASE, PubMed, and Cochrane library) and the abstracts of the American Society of Clinical Oncology annual meeting and European Society of Medical Oncology were searched to identify related studies. 95% confidence intervals (CIs), summary incidences, and relative risk (RR) were calculated utilizing either fixed-effects models on the basis of the heterogeneity of the included studies or random-effects.

Results

Seventy-two randomized controlled trials (including 30013 patients) were involved. The total incidence of high-grade and all-grade hypertensive events along with VEGFR-TKIs was 23.0% (95% CI, 20.1–26.0%) and 4.4% (95% CI, 3.7–5.0%), respectively. The use of VEGFR-TKIs remarkably enhanced the venture of developing high-grade (RR, 4.60; 95% CI, 3.92–5.40; P < 0.001) and all-grade (RR, 3.85; 95% CI, 3.37–4.40; P < 0.001) hypertensive events. Subgroup analyses revealed that the risk of a hypertensive event varied significantly in accordance with tumor type, VEGFR-TKI, trial phase, VEGFR-TKIs-based regimen, control therapy, and chemotherapy regimen.

Conclusions

Patients with cancer that receive VEGFR-TKIs are at a remarkable venture of developing hypertension. Therefore, suitable treatment and monitoring should be introduced to avoid cardiovascular complications.

Prevalence of KRAS mutations in metastatic colorectal cancer: A retrospective observational study from India

BACKGROUND

One of the genetic alterations implicated in tumor progression in colorectal cancers (CRCs) are abnormalities in Kristen Rat Sarcoma (KRAS) gene. Evaluation of KRAS mutation status is an important prognostic factor and has predictive value in deciding first line therapy based on monoclonal antibodies such as Cetuximab and Panitumumab in metastatic CRCs.

MATERIALS AND METHODS

In this retrospective study, we analyzed 7 different somatic mutations in Exon 2 of KRAS gene in 299 unselected incidental CRC patients who visited the hospital for clinical management during the period 2009-2013. Most of the tumors were primarily originating from colon and rectum; nevertheless, there were a few from rectosigmoid, sigmoid, ceacum and anal canal in the study group. Genomic DNA extracted from paraffin embedded tumor tissues was screened for 7 point mutations located in Codons 12 and 13 of KRAS gene, using Scorpions amplified refractory mutation system real time polymerase chain reaction technology. Statistical analysis was performed to assess bivariate relationship between different variables that includes: mutation status, mutation type, tumor location, tumor morphology, age and sex.

RESULTS

Prevalence of mutation in Codons 12 and 13 was 42.8% in the study group. Well-differentiated tumors had significantly more mutation positivity than moderately and poorly differentiated tumors (P = 0.001). 92% of the mutations were from Codon 12 and 8% in Codon 13. Glycine to Arginine was relatively more common in rectosigmoid followed by ceacum, while Glycine to Alanine mutation was relatively more prevalent in sigmoid, followed by rectum and rectosigmoid.

CONCLUSION

The results suggest a prevalence of KRAS mutation at 42.8% in Indian population indicating that this testing is very crucial for targeted therapy management in metastatic CRC in India. Further analysis on mutation status of other homologues such as NRAS and downstream partner, v-raf murine sarcoma viral oncogene homolog B1, would add value to understanding the role of anti-epidermal growth factor receptor therapy in CRC management.

Primary and Acquired Resistance of Colorectal Cancer to Anti-EGFR Monoclonal Antibody Can Be Overcome by Combined Treatment of Regorafenib with Cetuximab

PURPOSE

In colorectal cancer, the activation of the intracellular RAS-RAF and PIK3CA-AKT pathways has been implicated in the resistance to anti-EGFR mAbs. We have investigated the role of regorafenib, an oral multikinase inhibitor, in combination with cetuximab, an anti-EGFR mAb, to overcome anti-EGFR resistance.

EXPERIMENTAL DESIGN

We have tested, in vitro and in vivo, the effects of regorafenib in a panel of human colorectal cancer cell lines with a KRAS mutation (SW480, SW620, HCT116, LOVO, and HCT15) or with a BRAF mutation (HT29), as models of intrinsic resistance to cetuximab treatment, and in two human colorectal cancer cell lines (GEO and SW48) that are cetuximab-sensitive, as well as in their derived cells with acquired resistance to cetuximab (GEO-CR and SW48-CR).

RESULTS

Treatment with regorafenib determined a dose-dependent growth inhibition in all colorectal cancer cell lines. The combined treatment with cetuximab and regorafenib induced synergistic antiproliferative and apoptotic effects in cetuximab-resistant cell lines by blocking MAPK and AKT pathways. Nude mice were injected s.c. with HCT116, HCT15, GEO-CR, and SW48-CR cells. The combined treatment caused significant tumor growth inhibition. Synergistic antitumor activity of regorafenib plus cetuximab was also observed in an orthotopic colorectal cancer model of HCT116 cells. In particular, the combined treatment induced a significant tumor growth inhibition in the primary tumor site (cecum) and completely prevented metastasis formation.

CONCLUSIONS

The combined treatment with cetuximab and regorafenib could be a strategy to overcome resistance to anti-EGFR therapies in metastatic colorectal cancer patients.

Anti-EGFR monoclonal antibodies for treatment of colorectal cancers: development of cetuximab and panitumumab

Over the last decade, anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs) have been firmly established as essential drugs for the treatment of metastatic colorectal cancer (CRC). Cetuximab and panitumumab have been approved by American and European drug agencies. This review aims at exploring the main outcomes of clinical studies performed during their clinical development, from phase I to III trials, and hence at giving a comprehensive review of the scientific rational and up-to-date evidence sustaining the use of these drugs. Many areas are still under active investigation such as administration schedules, their efficacy in comparison with bevacizumab, their role in adjuvant therapy, molecular predictors, and management of side effects.

KRAS mutation in patients with metastatic colorectal cancer does not preclude benefit from oxaliplatin-or irinotecan-based treatment

Fluoropyrimidine-based chemotherapy plus antibody therapy is currently the standard first-line treatment for metastatic colorectal cancer (mCRC). In this study, we investigated the hypothesis that mutations in several of the targeted oncogenes are correlated with treatment outcomes in mCRC patients receiving different first-line regimens. Our study included a total of 194 patients who had undergone various forms of first-line chemotherapy. The KRAS, BRAF, PIK3CA, NRAS and AKT1 mutational status of the tumors was assessed and the association between mutational status and treatment outcome was evaluated. The median progression-free survival (mPFS) of the wild-type and mutated KRAS subgroups that had received oxaliplatin-based treatment was 8.6 and 6.8 months, respectively (P=0.41), whereas the mPFS of the wild-type KRAS, BRAF, PIK3CA, NRAS and AKT1 subgroups and that of their respective mutant subgroups was 9.7 and 7.2 months, respectively (P=0.10). The mPFS of the wild-type and mutated KRAS subgroups that had received irinotecan-based treatments was 7.7 and 9.7 months, respectively (P= 0.43). The mPFS of the wild-type KRAS, BRAF, PIK3CA, NRAS and AKT1 subgroups and that of their respective mutant subgroups was 7.1 and 10.0 months, respectively (P=0.76). Our data indicated that mCRC patients with activation of KRAS, BRAF, PIK3CA, NRAS and AKT1 mutations, even those being treated with oxaliplatin- and irinotecan-based regimens as first-line treatment, may benefit from cytotoxic drug therapy.

Clinical Implementation of KRAS Testing in Metastatic Colorectal Carcinoma: The Pathologist's Perspective

Context.—Mutation status of the KRAS gene identifies a distinct disease subtype of metastatic colorectal carcinoma that does not respond to antibody therapeutics targeting the epidermal growth factor receptor. This is currently the only validated marker in metastatic colorectal carcinoma with a clear implication in treatment selection. KRAS testing is widely accepted in clinical practice to guide metastatic colorectal carcinoma therapeutic decisions, and there are many commercially available platforms to perform the test.

Objective.—To evaluate the critical role of pathologists in the full implementation of KRAS testing by optimizing tumor tissue collection and fixation procedures and by choosing testing technologies and reliable Clinical Laboratory Improvement Amendments of 1988–certified laboratories to perform the tests.

Data Sources.—Prospective clinical trials, retrospective studies, and quality assessment and survey reports were identified in the following databases: PubMed, American Society of Clinical Oncology Proceedings (American Society of Clinical Oncology Annual Meeting and Gastrointestinal Cancer Symposium) and European Society for Medical Oncology Proceedings (Annals of Oncology European Society for Medical Oncology Congress and Annals of Oncology World Congress on Gastrointestinal Cancers).

Conclusions.—More bona fide standards are needed to address the variety of available test methods, which have different performance characteristics including speed, sensitivity to detect rare mutations, and technical requirements. Refined standards addressing timing of KRAS testing, laboratory performance and accuracy, quality assurance and control, proper tissue collection, and appropriate result reporting would also be greatly beneficial. Pathologists should be aware that the amount of information they need to manage will increase, because future trends and technological advances will enhance the predictive power of diagnostic tests or the scope of the biomarker panels tested routinely across tumor types.

BEYOND KRAS: Other markers and potential treatment strategies for KRAS mutant and wild-type patients

Despite the advances and new drug discoveries, the best drug in metastatic colorectal cancer (mcrc) is 5-fluorouracil. This drug is the backbone of FOLFOX and FOLFIRI which are the standard first line cytotoxic regimens in the metastatic setting. The efficacies of these two regimens are equivalent, and the selection of one over the other is largely based on the side effect profile. Bevacizumab is commonly added to each of these regimes in the first line setting. When a patient develops progression of disease on FOLFOX, then treatment with either single agent irinotecan, or FOLFIRI is a typical approach. If FOLFIRI-BEV is used in first line, the FOLFOX is typically given in second line. All patients with metastatic colorectal cancer have their tumor tested for the KRAS mutation in exon 2. If the tumor is KRAS wild-type then either cetuximab or panitumumab, with or without continued irinotecan, may be used. In patients whose tumors are symptomatic, and so requiring a rapid response, cetuximab or panitumumab may be incorporated into second line therapy instead of third line. There are no data supporting the use of cetuximab after progression on panitumumab or vice versa and use of one of these agents after failure on the other is not appropriate. Upon progression on the standard chemotherapies outlined above appropriate patients may be offered participation in a clinical trial. For patients whose tumors are KRAS mutant a clinical trial should be considered upon progression on oxaliplatin and irinotecan-based regimens. New agents and combinations of targeted therapies described below offer promising therapies for patients with both KRAS wild type and mutant tumors. As our molecular knowledge of mcrc advances future therapies will likely tailor an individualized approach based on tumor specific molecular markers.

Progress in metastatic colorectal cancer: growing role of cetuximab to optimize clinical outcome

The prognosis of metastatic colorectal cancer remains poor despite advances made in recent years, particularly with new treatments directed towards molecular targets. Cetuximab, a chimeric immunoglobulin (Ig)G1 monoclonal antibody that targets the ligand-binding domain of the epidermal growth factor receptor (EGFR), is active in metastatic colorectal cancer. As an IgG1 antibody, cetuximab may exert its antitumour efficacy through both EGFR antagonism and antibody-dependent cell-mediated cytotoxicity. The benefits of cetuximab in metastatic colorectal cancer are well documented in clinical trials and are acknowledged in the approval and licensing of this agent. There is evidence of the role of cetuximab not only in irinotecan-refractory or heavily pretreated patients, but also of the efficacy and safety of the addition of this agent to FOLFIRI (irinotecan/5-fluorouracil/leucovorin) in first-line metastatic colorectal cancer, with an enhanced effect in 5-fluorouracil patients with Kirsten rat sarcoma (KRAS) wild-type tumours. In these patients, a recent meta-analysis of the pooled Cetuximab Combined with Irinotecan in First-Line Therapy for Metastatic Colorectal Cancer (CRYSTAL) and Oxaliplatin and Cetuximab in First-Line Treatment of mCRC (OPUS) patient populations confirms that the addition of cetuximab to first-line chemotherapy achieves a statistically significant improvement in the best overall response, overall survival time, and progression-free survival (PSF) compared with chemotherapy alone. In nonresectable colorectal liver metastases, cetuximab plus FOLFOX-6 (oxaliplatin/5-fluorouracil/leucovorin) or cetuximab plus FOLFIRI increased significantly resectability of liver metastases, including R0 resections. Also, preliminary data indicate that cetuximab can be administered in a more convenient 2-week schedule in combination with standard chemotherapy. Cetuximab is generally well tolerated. Acne-form rash is the most frequent toxicity. Up to the present time, the results obtained with targeted therapy combinations are not as encouraging as initially expected. The identification of biomarkers associated with disease control, including KRAS and BRAF mutation status in patients treated with cetuximab, is changing the current management of metastatic colorectal cancer. Clinical and molecular predictive markers of response are under active evaluation in order to better select patients who could benefit from cetuximab treatment, with the aim of both optimising patient outcomes and avoiding unnecessary toxicities.

Understanding resistance to EGFR inhibitors-impact on future treatment strategies

EGFR is a tyrosine kinase that participates in the regulation of cellular homeostasis. Following ligand binding, EGFR stimulates downstream cell signaling cascades that influence cell proliferation, apoptosis, migration, survival and complex processes, including angiogenesis and tumorigenesis. EGFR has been strongly implicated in the biology of human epithelial malignancies, with therapeutic applications in cancers of the colon, head and neck, lung, and pancreas. Accordingly, targeting EGFR has been intensely pursued, with the development of a series of promising molecular inhibitors for use in clinical oncology. As is common in cancer therapy, challenges with respect to treatment resistance emerge over time. This situation is certainly true of EGFR inhibitor therapies, where intrinsic and acquired resistance is now well recognized. In this Review, we provide a brief overview regarding the biology of EGFR, preclinical and clinical development of EGFR inhibitors, and molecular mechanisms that underlie the development of treatment resistance. A greater understanding of the mechanisms that lead to EGFR resistance may provide valuable insights to help design new strategies that will enhance the impact of this promising class of inhibitors for the treatment of cancer.

Cetuximab-based therapy vs noncetuximab therapy in advanced or metastatic colorectal cancer: a meta-analysis of seven randomized controlled trials

PURPOSE

A meta-analysis was performed to assess the efficacy and safety of cetuximab-based therapy vs noncetuximab therapy in advanced or metastatic colorectal cancer.

METHOD

A total of 4617 patients from seven randomized controlled trials were available for analysis, with 2305 patients in the cetuximab group and 2312 patients in the noncetuximab group. The efficacy data included progression-free survival (PFS), overall survival (OS) and overall response rate (ORR). The safety data that contained overall grade 3 and 4 adverse events (AEs), specific grade 3 and 4 toxicity such as acneiform rash, cetuximab-related skin toxicity, diarrhoea, fatigue, neutropenia, hypertension, nausea and hand-foot skin reaction are evaluated.

RESULT

There was a significant PFS benefit in favour of cetuximab-based therapy (HR = 0.68, 95%CI: 0.63 to 0.73) and OS benefit (HR = 0.90, 95%CI: 0.81 to 1.00). The ORR was significantly higher in the cetuximab-based arm (OR = 2.19, 95% CI: 1.30 to 3.68). The incidence of overall grade 3-4 toxicity was significantly higher in the cetuximab arm compared with the noncetuximab arm (61.2%vs 43.0%, OR = 2.32, 95%CI: 1.59-3.39). This difference was mainly attributed to cetuximab-related skin toxicity (OR = 5.86, 95%CI: 1.38-24.88), especially acneiform rash (OR = 51.37, 95%CI: 22.75-116.02). In addition, cetuximab resulted in a significant increase in grade 3 and 4 diarrhoea, fatigue and neutropenia, except for hypertension, nausea and hand-foot skin reaction.

CONCLUSION

Cetuximab-based therapy improves PFS and OS resulting in better ORR vs noncetuximab therapy. Its most common and severe AE is skin toxicity that should be predictable and manageable.

Targeting multiple kinase pathways: a change in paradigm

Anticancer drugs that target protein kinases include small molecule inhibitors and monoclonal antibodies. Feedback loops and cross talk between signaling pathways impact significantly on the efficacy of cancer therapeutics, and resistance to targeted agents is a major barrier to effective treatments. Increasingly, therapies are being designed to target multiple kinase pathways. This can be achieved using a single agent that inhibits multiple signaling pathways or a combination of highly selective agents. In this review we discuss the principles of specifically targeting multiple kinase pathways with particular reference to angiogenic signaling pathways.

Evolving treatment of advanced colorectal cancer

Advances in colorectal cancer treatment have led to improved outcomes for patients. A number of cytotoxic agents, alone and in combination, have shown activity. The addition of the newer, so-called "targeted" agents to standard chemotherapy drugs and regimens has also modestly improved outcomes. Progress in our knowledge and understanding of molecular pathways has led to the identification of markers critical in determining response or nonresponse to some of the targeted agents. This review discusses the available therapies in metastatic colorectal cancer and describes some of the molecular markers implicated in activity and resistance to current targeted therapies.

Predicting response to EGFR inhibitors in metastatic colorectal cancer: current practice and future directions

The identification of KRAS mutational status as a predictive marker of response to antibodies against the epidermal growth factor receptor (EGFR) has been one of the most significant and practice-changing recent advances in colorectal cancer research. Recently, data suggesting a potential role for other markers (including BRAF mutations, loss of phosphatase and tension homologue deleted on chromosome ten expression, and phosphatidylinositol-3-kinase-AKT pathway mutations) in predicting response to anti-EGFR therapy have emerged. Ongoing clinical trials and correlative analyses are essential to definitively identify predictive markers and develop therapeutic strategies for patients who may not derive benefit from anti-EGFR therapy. This article reviews recent clinical trials supporting the predictive role of KRAS, recent changes to clinical guidelines and pharmaceutical labeling, investigational predictive molecular markers, and newer clinical trials targeting patients with mutated KRAS.

Mechanisms of resistance to HER family targeting antibodies

The epidermal growth factor (EGF) family of receptor tyrosine kinases consists of four members: EGFR (HER1/ErbB1), HER2/neu (ErbB2), HER3 (ErbB3) and HER4 (ErbB4). Receptor activation via ligand binding leads to downstream signaling that influence cell proliferation, angiogenesis, invasion and metastasis. Aberrant expression or activity of EGFR and HER2 have been strongly linked to the etiology of several human epithelial cancers including but not limited to head and neck squamous cell carcinoma (HNSCC), non-small cell lung cancer (NSCLC), colorectal cancer (CRC), and breast cancer. With this, intense efforts have been made to inhibit the activity of the EGFR and HER2 by designing antibodies against the ligand binding domains (cetuximab, panitumumab and trastuzumab) or small molecules against the tyrosine kinase domains (erlotinib, gefitinib, and lapatinib). Both approaches have shown considerable clinical promise. However, increasing evidence suggests that the majority of patients do not respond to these therapies, and those who show initial response ultimately become refractory to treatment. While mechanisms of resistance to tyrosine kinase inhibitors have been extensively studied, resistance to monoclonal antibodies is less well understood, both in the laboratory and in the clinical setting. In this review, we discuss resistance to antibody-based therapies against the EGFR and HER2, similarities between these resistance profiles, and strategies to overcome resistance to HER family targeting monoclonal antibody therapy.

KRAS and BRAF mutations in advanced colorectal cancer are associated with poor prognosis but do not preclude benefit from oxaliplatin or irinotecan: results from the MRC FOCUS trial

PURPOSE

Activating mutation of the KRAS oncogene is an established predictive biomarker for resistance to anti-epidermal growth factor receptor (anti-EGFR) therapies in advanced colorectal cancer (aCRC). We wanted to determine whether KRAS and/or BRAF mutation is also a predictive biomarker for other aCRC therapies.

PATIENTS AND METHODS

The Medical Research Council Fluorouracil, Oxaliplatin and Irinotecan: Use and Sequencing (MRC FOCUS) trial compared treatment sequences including first-line fluorouracil (FU), FU/irinotecan or FU/oxaliplatin in aCRC. Tumor blocks were obtained from 711 consenting patients. DNA was extracted and KRAS codons 12, 13, and 61 and BRAF codon 600 were assessed by pyrosequencing. Mutation (mut) status was assessed first as a prognostic factor and then as a predictive biomarker for the benefit of adding irinotecan or oxaliplatin to FU. The association of BRAF-mut with loss of MLH1 was assessed by immunohistochemistry.

RESULTS

Three hundred eight (43.3%) of 711 patients had KRAS-mut and 56 (7.9%) of 711 had BRAF-mut. Mutation of KRAS, BRAF, or both was present in 360 (50.6%) of 711 patients. Mutation in either KRAS or BRAF was a poor prognostic factor for overall survival (OS; hazard ratio [HR], 1.40; 95% CI, 1.20 to 1.65; P < .0001) but had minimal impact on progression-free survival (PFS; HR, 1.16; 95% CI, 1.00 to 1.36; P = .05). Mutation status did not affect the impact of irinotecan or oxaliplatin on PFS or OS. BRAF-mut was weakly associated with loss of MLH1 staining (P = .012).

CONCLUSION

KRAS/BRAF mutation is associated with poor prognosis but is not a predictive biomarker for irinotecan or oxaliplatin. There is no evidence that patients with KRAS/BRAF mutated tumors are less likely to benefit from these standard chemotherapy agents.

Dose finding and early efficacy study of gemcitabine plus capecitabine in combination with bevacizumab plus erlotinib in advanced pancreatic cancer

PURPOSE

This study evaluated safety and efficacy of chemotherapy (gemcitabine plus capecitabine) plus bevacizumab/erlotinib in advanced pancreatic cancer because dual epidermal growth factor receptor/vascular endothelial growth factor blockade has a rational biologic basis in this malignancy.

PATIENTS AND METHODS

Patients with untreated, unresectable, locally advanced or metastatic pancreatic carcinoma were enrolled onto one of the following four sequential dose levels (DLs) of escalating capecitabine doses (days 1 to 21): DL1, 910 mg/m(2); DL2, 1,160 mg/m(2); DL3, 1,400 mg/m(2); or DL4, 1,660 mg/m(2). Doses of coadministered gemcitabine (1,000 mg/m(2) on days 1, 8, and 15), bevacizumab (5 mg/kg on days 1 and 15), and erlotinib (100 mg/d) every 28 days (up to six cycles) were fixed. Using a 3+3 study design, dose-limiting toxicity (DLT) was assessed in cycle 1. Results Twenty assessable patients were enrolled (DL1, n = 8; DL2, n = 3; DL3, n = 6; and DL4, n = 3); 97 cycles were administered. Median age was 63 years (range, 33 to 77 years), and male-to-female ratio was 10:10. Performance status was 0 and 1 in two and 17 patients, respectively; and nine and 11 patients had locally advanced and metastatic disease, respectively. DLT occurred in one patient at DL1 (grade 3 epistaxis) and two patients at DL4 (grade 3 diarrhea and grade 3 skin rash > 7 days). Common grade 3 and 4 toxicities (10% to 20%) were diarrhea, hand-foot syndrome, stomatitis, and skin rash. Grade 3 lethargy and grade 3 or 4 neutropenia occurred in 40% and 45% of patients, respectively. No GI perforation, grade 3 GI hemorrhage/hypertension, or pneumonitis occurred. Ten partial responses were observed. Median overall and progression-survival times (all patients) were 12.5 and 9.0 months, respectively.

CONCLUSION

The maximum-tolerated dose of capecitabine was 1,660 mg/m(2). The recommended capecitabine dose in this cytotoxic doublet/biologic doublet regimen is 1,440 mg/m(2); this regimen is under evaluation in an ongoing phase II study.

The role of KRAS mutation testing in the management of patients with metastatic colorectal cancer

CONTEXT

KRAS mutations can be detected in approximately 30% to 40% of all patients with colorectal cancer. Several recent studies have shown that patients with KRAS mutations in codons 12 or 13 in metastatic tumors do not benefit from anti-epidermal growth factor receptor therapy with cetuximab or panitumumab.

OBJECTIVE

To review the literature on the role of KRAS mutation testing for management of patients with metastatic colorectal cancer and to discuss testing strategies.

DATA SOURCES

This review is based on published, peer-reviewed literature; available information from medical organizations (eg, National Comprehensive Cancer Network, American Society of Clinical Oncology, College of American Pathologists); and information from clinical laboratories conducting KRAS mutation analysis.

CONCLUSIONS

Multiple methods for detecting KRAS mutations in colorectal tumors are available, and all methods in current clinical use appear to have adequate clinical sensitivity for predicting a lack of response to cetuximab and panitumumab. Pathologist expertise is essential to quality KRAS testing and to determining effective treatment for patients with metastatic colorectal cancer.

[The development of the first line treatment of metastatic colorectal cancer (mCRC)]

Chemotherapy options of metastatic colorectal cancer (mCRC) have been progressed rapidly in the last years. Besides of the standard fluorouracil/folinic acid treatment some new active agents (oxaliplatin and irinotecan) have been introduced, and more recently the "targeted" biologicals (bevacizumab, cetuximab, panitumumab) have demonstrated their high effectiveness. This review summarizes the development of the first line treatment of mCRC.

Anti-angiogenic therapies for metastatic colorectal cancer

BACKGROUND

Angiogenesis inhibitors have been developed to block tumour angiogenesis and target vascular endothelial cells. While some of them have already been approved by the health authorities and are successfully integrated into patient care, many others are still under development, and the clinical value of this approach has to be established.

OBJECTIVES

To assess the efficacy and toxicity of targeted anti-angiogenic therapies, in addition to chemotherapy, in patients with metastatic colorectal cancer. Primary endpoints are both progression-free and overall survival. Response rates, toxicity and secondary resectability were secondary endpoints. Comparisons were first-line chemotherapy in combination with angiogenesis inhibitor, to the same chemotherapy without angiogenesis inhibitor; and second-line chemotherapy, to the same chemotherapy without angiogenesis inhibitor.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, as well as proceedings from ECCO, ESMO and ASCO until November 2008. In addition, reference lists from trials were scanned, experts in the field and drug manufacturers were contacted to obtain further information.

SELECTION CRITERIA

Randomized controlled trials on targeted anti-angiogenic drugs in metastatic colorectal cancer (MCRC).

DATA COLLECTION AND ANALYSIS

Data collection and analysis was performed, according to a previously published protocol. Because individual patient data was not provided, aggregate data had to be used for the analysis. Summary statistics for the primary endpoints were hazard ratios (HR's) and their 95% confidence intervals.

MAIN RESULTS

At present, eligible first line trials for this meta-analysis were available for bevacizumab (5 trials including 3101 patients) and vatalanib (1 trial which included 1168 patients). The overall HR s for PFS (0.61, 95% CI 0.45 - 0.83) and OS (0.81, 95% 0.73 - 0.90) for the comparison of first-line chemotherapy, with or without bevacizumab, confirms significant benefits in favour of the patients treated with bevacizumab. However, the effect on PFS shows significant heterogeneity. For second-line chemotherapy, with or without bevacizumab, a benefit in both PFS (HR 0.61, 95% CI 0.51 - 0.73) and OS (HR 0.75, 95% CI 0.63-0.89) was demonstrated in a single, randomized trial. While differences in treatment-related deaths and 60-day mortality were not significant, higher incidences in grade III/IV hypertension, arterial thrombembolic events and gastrointestinal perforations were observed in the patients treated with bevacizumab. For valatanib, currently available data showed a non-significant benefit in PFS and OS.

AUTHORS' CONCLUSIONS

The addition of bevacizumab to chemotherapy of metastatic colorectal cancer prolongs both PFS and OS in first-and second-line therapy.

Irinotecan as palliative chemotherapy for metastatic colorectal cancer: evolving tactics following initial treatment

BACKGROUND

Patients with metastatic colorectal cancer (mCRC) who progress despite treatment with fluoropyrimidine and irinotecan or oxaliplatin have diminished survival, but they may derive clinically meaningful benefit from second-line or later chemotherapy.

MATERIALS AND METHODS

Literature from 2000 through mid-2008 on the treatment of patients with unresectable mCRC was reviewed to identify options for chemotherapy-resistant patients with mCRC.

RESULTS AND CONCLUSIONS

A recurring finding is that overall survival increases when patients are exposed to all available active agents throughout their course of care, independent of the line of treatment in which medication is delivered. Sequential administration of agents, including irinotecan, oxaliplatin, bevacizumab, and cetuximab, or, alternatively, deferred administration of various medications in combination, have shown promising efficacy that is at least equivalent to established combination regimens with the same agents. Palliative chemotherapy clearly improves survival in patients with unresectable mCRC, with overall survival recently reaching 28 months.

Chemotherapy with targeted agents for the treatment of metastatic colorectal cancer

The introduction of novel agents targeted to specific molecular features of cancer cells promises more options and marked improvements in efficacy for treatment of colon cancer. This overview of clinical studies describes the effects of administering the targeted agents bevacizumab, cetuximab, and panitumumab, also known as monoclonal antibodies, to treat metastatic colorectal cancer (mCRC) patients. All three targeted agents have been approved for use by the U.S. Food and Drug Administration and the European Agency for the Evaluation of Medicinal Products. Bevacizumab has been shown to extend survival when used in combination with irinotecan and 5-fluorouracil-based chemotherapy, and the addition of cetuximab to irinotecan and 5-fluorouracil-based chemotherapy overcomes irinotecan resistance. Cetuximab and panitumumab are both efficacious among refractory mCRC patients with wild-type KRAS tumors. Other targeted agents, for example, the tyrosine kinase inhibitors erlotinib, gefitinib, sunitinib, and vatalanib (PTK787/ZK 222584), are currently in various stages of clinical development.

Individualized therapies in colorectal cancer: KRAS as a marker for response to EGFR-targeted therapy

Individualized therapies that are tailored to a patient's genetic composition will be of tremendous value for treatment of cancer. Recently, Kirsten ras (KRAS) status has emerged as a predictor of response to epidermal growth factor receptor (EGFR) targeted therapies. In this article, we will discuss targeted therapies for colorectal cancers (CRC) based on EGFR signaling pathway and review published data about the potential usefulness of KRAS as a biological marker for response to these therapies. Results from relevant studies published since 2005 and unpublished results presented at national meetings were retrieved and summarized. These studies reflected response (or lack of response) to EGFR-targeted therapies in patients with metastatic CRC as a function of KRAS status. It has become clear that patients with colorectal cancer whose tumor has an activating mutation in KRAS do not respond to monoclonal antibody therapies targeting EGFR. It should now become a standard practice that any patients being considered for EGFR targeted therapies have their tumors tested for KRAS status and only those with wild-type KRAS being offered such therapies.

Pharmacogenetics in chemotherapy of colorectal cancer

Although in recent years, chemotherapeutic options for colorectal carcinoma have expanded, overall response rates are still too low, with high rates of toxicity. Pharmacogenetics aim at predicting both treatment response and adverse effects in individual patients. This review describes the current knowledge of pharmacogenetic markers in the systemic treatment of colorectal cancer. UGT1A1*28 leads to reduced conjugation of SN-38, the active metabolite of irinotecan, resulting in an increased rate of adverse effects, especially neutropenia. To a lesser extent, increased 5-FU toxicity is predicted by DPYD*2A. A variable number of tandem repeats polymorphism in the thymidylate synthase enhancer region, in combination with a single nucleotide polymorphism C>G, may predict poorer response to 5-FU. Efficacy of oxaliplatin is influenced by polymorphisms in components of DNA repair systems, such as ERCC1 and XRCC1. Polymorphic changes in the endothelial growth factor receptor probably predict cetuximab efficacy. Furthermore, the antibody-depended cell-mediated cytotoxic effect of cetuximab may be reduced by polymorphisms in the immunoglobin G fragment C receptors. Bevacizumab efficacy is suspected to be influenced by polymorphisms in the VEGF gene and the hypoxia inducible factor 1alpha gene. Although the interpretation of pharmacogenetic studies is complicated, results imply a promising way of pretreatment prediction of chemotherapy efficacy and toxicity.

Health-related quality of life in patients with advanced colorectal cancer treated with cetuximab: overall and KRAS-specific results of the NCIC CTG and AGITG CO.17 Trial

PURPOSE

National Cancer Institute of Canada Clinical Trials Group CO.17 demonstrated the antiepidermal growth factor receptor (anti-EGFR) monoclonal antibody cetuximab improves overall and progression-free survival in patients with advanced, chemotherapy-refractory colorectal cancer (CRC), particularly in patients with wild-type KRAS tumors. This article reports the health-related quality-of-life (HRQL) outcomes from CO.17.

PATIENTS AND METHODS

Patients (N = 572) with pretreated EGFR-detectable advanced CRC were randomly assigned to cetuximab and best supportive care (BSC) or to BSC alone. HRQL primary end points assessed by the EORTC QLQ-C30 were physical function (PF) and global health status (GHS); mean changes from baseline to 8 and 16 weeks were assessed. Post hoc analysis by KRAS mutation status was performed.

RESULTS

Questionnaire compliance was 94% at baseline, but it declined differentially (67% v 47% for cetuximab v BSC at 16 weeks). PF change scores were -3.9 for cetuximab and -8.6 for BSC (P = .046) at 8 weeks and were -5.9 and -12.5 for cetuximab and BSC, respectively, (P = .027) at 16 weeks. GHS change scores were -0.5 and -7.1 (P = .008) at 8 weeks and were -3.6 and -15.2 (P = .008) at 16 weeks for cetuximab and BSC, respectively. In patients who had tumors with wild-type KRAS status, cetuximab resulted in less PF deterioration at 8 weeks (-0.7 v -7.2; P = .11) and 16 weeks (-3.4 v -13.8; P = .008) compared with BSC. Patients with wild-type status who received cetuximab experienced improved GHS at 8 weeks, whereas patients who received BSC alone deteriorated (3.2 v -7.7; P = .002). Cetuximab preserved GHS at 16 weeks (-0.2 v -18.1; P < .001). No significant differences were noted between study arms for patients with mutated KRAS tumors.

CONCLUSION

Cetuximab offers important HRQL and survival benefits for pretreated patients with advanced, wild-type KRAS CRC.

Adapting Practice in the Face of New Data

Oncologists are often faced with new information on tests, therapies, and treatment regimens. Determining how to incorporate that data into practice patterns is not easy. Regardless of what motivates you to make a change in practice, the explosion of new oncology data demands that you continually reevaluate how you practice.

ASCO Provisional Clinical Opinion: KRAS, Cetuximab, and Panitumumab-Clinical Implications in Colorectal Cancer

ASCO's Provisional Clinical Opinion alerts oncologists to emerging information from recent clinical trials that can assist them in treatment selection. Evidence suggests that cetuximab and panitumumab are ineffective in patients with KRAS mutations at codon 12 or 13. Thus, patients with colorectal cancer with these mutations should be spared the toxicity and cost of an ineffective therapy.

The role of targeted therapy in the treatment of advanced colorectal cancer

The introduction of targeted therapies in the treatment of metastatic colorectal cancer (MCRC) has resulted in significant improvements in efficacy outcomes. Both vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) inhibitors have proven to be valid and valuable agents in the management of MCRC. This review will focus on the role of the anti-VEGF monoclonal antibody, bevacizumab, and the anti-EGFR monoclonal antibodies, cetuximab and panitumumab, in MCRC. Special focus will be placed on clinical evidence supporting the use of these agents in various lines of treatment, and on KRAS as a marker of response in relationship to anti-EGFR inhibitors.

[What are the new therapeutic strategies in metastatic colorectal cancer including biotherapies?]

Colorectal cancer remains one of the major causes of cancer death. Recent identification of new molecular targets led to the development of novel agents directed against growth factor receptors or key factors of angiogenesis. Recent phase III trials demonstrated a significant clinical benefit with bevacizumab, a VEGF inhibitor, and with EGFR-inhibitors, namely cetuximab and panitumumab. In this article we review the diverse treatment options combining cytotoxic and targeted therapies available for patients with metastatic colorectal cancer.

Updates in Gastrointestinal Oncology - insights from the 2008 44th annual meeting of the American Society of Clinical Oncology

We have reviewed the pivotal presentations rcelated to colorectal cancer (CRC) and other gastrointestinal malignancies from 2008 annual meeting of the American Society of Clinical Oncology (ASCO). We have discussed the scientific findings and the impact on practice guidelines and ongoing clinical trials. The report on KRAS status in patients with metastatic CRC receiving epidermal growth factor receptor (EGFR) targeted antibody treatment has led to a change in National Comprehensive Cancer Network guideline that recommends only patients with wild-type KRAS tumor should receive this treatment. The results of double biologics (bevacizumab and anti-EGFR antibody) plus chemotherapy as first-line treatment in patients with metastatic CRC has shown a worse outcome than bevacizumab-based regimen. Microsatellite Instability has again been confirmed to be an important predictor in patients with stage II colon cancer receiving adjuvant treatment. Adjuvant gemcitabine therapy for pancreatic cancer was investigated by the CONKO-001 study; this resulted in superior survival as compared with observation and can be regarded as an acceptable option, without the addition of radiotherapy. The addition of bevacizumab to gemcitabine and erlotinib was not supior to gemcitabine and erlotinib for advanced disease. Second-line therapy for advanced pancreatic cancer with 5-fluorouracil and oxaliplatin resulted in a survival benefit. Irinotecan plus cisplatin and paclitaxel plus cisplatin result in similar survival when combined with radiotherapy for esophageal cancer. The novel fluoropyrimidine S1 appears to be active in gastric cancer, as a single agent or as combination therapy. Adjuvant intraperitoneal mitomycin-C may decrease the incidence of peritoneal recurrence of gastric cancer. Sorafenib is an effective agent in Asian patients with hepatocellular carcinoma secondary to hepatitis B; its utility in child's B cirrhosis remains to be proven. Sunitinib is also an active agent in hepatocellular carcinoma, and may represent an alterative to sorafenib for advanced disease. These and other important presentations from the 2008 ASCO annual meeting are discussed in this article.

American Society of Clinical Oncology provisional clinical opinion: testing for KRAS gene mutations in patients with metastatic colorectal carcinoma to predict response to anti-epidermal growth factor receptor monoclonal antibody therapy

PURPOSE

An American Society of Clinical Oncology (ASCO) provisional clinical opinion (PCO), offers timely clinical direction to ASCO's oncologists following publication or presentation of potentially practice-changing data from major studies. This PCO addresses the utility of KRAS gene mutation testing in patients with metastatic colorectal carcinoma to predict response to anti-epidermal growth factor receptor (anti-EGFR) monoclonal antibody (MoAb) therapy with cetuximab or panitumumab (see Note).

CLINICAL CONTEXT

Recent results from phase II and III clinical trials demonstrate that patients with metastatic colorectal cancer benefit from therapy with monoclonal antibodies directed against the EGFR, when used either as monotherapy or combined with chemotherapy. Retrospective subset analyses of the data from these trials strongly suggest that patients who have KRAS mutations detected in codon 12 or 13 do not benefit from this therapy.

RECENT DATA

Five randomized controlled trials of cetuximab or panitumumab have evaluated outcomes for patients with metastatic colorectal carcinoma in relation to KRAS mutational status as no mutation detected (wild type) or abnormal (mutated). Another five single-arm studies have retrospectively evaluated tumor response according to KRAS status.

PROVISIONAL CLINICAL OPINION

Based on systematic reviews of the relevant literature, all patients with metastatic colorectal carcinoma who are candidates for anti-EGFR antibody therapy should have their tumor tested for KRAS mutations in a CLIA-accredited laboratory. If KRAS mutation in codon 12 or 13 is detected, then patients with metastatic colorectal carcinoma should not receive anti-EGFR antibody therapy as part of their treatment.

NOTE

ASCO's provisional clinical opinions (PCOs) reflect expert consensus based on clinical evidence and literature available at the time they are written, and are intended to assist physicians in clinical decision-making and identify questions and settings for further research. Due to the rapid flow of scientific information in oncology, new evidence may have emerged since the time a PCO was submitted for publication. PCOs are not continually updated and may not reflect the most recent evidence. PCOs cannot account for individual variation among patients, and cannot be considered inclusive of all proper methods of care or exclusive of other treatments. It is the responsibility of the treating physician or other health care provider, relying on independent experience and knowledge of the patient, to determine the best course of treatment for the patient. Accordingly, adherence to any PCO is voluntary, with the ultimate determination regarding its application to be made by the physician in light of each patient's individual circumstances. ASCO PCOs describe the use of procedures and therapies in clinical practice and cannot be assumed to apply to the use of these interventions in the context of clinical trials. ASCO assumes no responsibility for any injury or damage to persons or property arising out of or related to any use of ASCO's PCOs, or for any errors or omissions.

Understanding the predictive role of K-ras for epidermal growth factor receptor-targeted therapies in colorectal cancer

The prognosis of metastatic colorectal cancer (mCRC) remains poor regardless of the advances obtained in recent years with new therapeutic agents, surgical procedures, and diagnostic methods. New treatments directed to molecular targets have emerged and are being developed to improve these results, but there is a need to optimize and define the best use of these new approaches. Current use of irinotecan, oxaliplatin, and bevacizumab combined with the long-time standards 5-fluorouracil and leucovorin as first- or second-line treatment for patients with mCRC has resulted in median overall survival figures of > 20 months. Additional improvements in treatment are likely to be facilitated by the use of rationally selected therapeutic agents that target functionally important proteins in tumor cells, such as the epidermal growth factor receptor (EGFR). The activation of EGFR leads to the activation of intracellular effectors involved in intracellular signaling pathways such as the G protein K-Ras. The K-Ras oncoprotein controls transduction of signals required for proliferation, differentiation, and survival, mainly acting as guanosine diphosphate/guanosine triphosphate-regulated binary switches located at the inner surface of the plasma membrane. Monoclonal antibodies (MoAbs) designed to bind to the ectodomain of the EGFR have shown activity in chemorefractory mCRC and in the first-line setting. Cetuximab and panitumumab are MoAbs that bind to the EGFR and thereby inhibit cell proliferation, metastasis, and angiogenesis. Recent clinical data confirm that the efficacy of cetuximab and panitumumab is confined to patients bearing tumors with wild-type K-ras. K-ras mutation analysis may now be considered a new standard of care in the selection of patients for EGFR-targeted therapy.

Vandetanib with FOLFIRI in patients with advanced colorectal adenocarcinoma: results from an open-label, multicentre Phase I study

PURPOSE

The safety and tolerability of vandetanib (ZACTIMA; ZD6474) plus FOLFIRI was investigated in patients with advanced colorectal cancer (CRC).

METHODS

Patients eligible for first- or second-line chemotherapy received once-daily oral doses of vandetanib (100 or 300 mg) plus 14-day treatment cycles of FOLFIRI.

RESULTS

A total of 21 patients received vandetanib 100 mg (n = 11) or 300 mg (n = 10) + FOLFIRI. Combination therapy was well tolerated at both vandetanib dose levels. There were no DLTs in the vandetanib 100 mg cohort and one DLT of hypertension (CTCAE grade 3) in the 300 mg cohort. The most common adverse events were diarrhoea (n = 20), nausea (n = 12) and fatigue (n = 10). Two patients (one in each cohort) discontinued vandetanib due to adverse events (rash, 100 mg cohort; hypertension, 300 mg cohort). There was no apparent pharmacokinetic interaction between vandetanib and FOLFIRI. Preliminary efficacy results included two confirmed partial responses in the 100 mg cohort and 9 patients with stable disease > or =8 weeks (100 mg, n = 7; 300 mg, n = 2).

CONCLUSIONS

Once-daily vandetanib (100 or 300 mg) in combination with a standard FOLFIRI regimen was generally well tolerated in patients with advanced CRC.

The clinical benefit of bevacizumab in metastatic colorectal cancer is independent of K-ras mutation status: analysis of a phase III study of bevacizumab with chemotherapy in previously untreated metastatic colorectal cancer

PURPOSE

Mutations of the K-ras gene were identified as a prognostic marker in metastatic colorectal cancer (mCRC). In addition, emerging data suggest that K-ras mutations are a negative predictor of clinical benefit from anti-epidermal growth factor receptor treatment in mCRC. Previously reported data suggest that the longer overall survival (OS) observed with bevacizumab treatment in mCRC is independent of alterations in the Ras/Raf/Mek/Erk pathway. We conducted additional analyses to better describe the clinical benefit of bevacizumab treatment in mCRC relative to K-ras mutation status.

PATIENTS AND METHODS

Additional statistical analyses were done with data from K-ras mutation analyses in 230 patients who were treated with irinotecan, fluorouracil, and leucovorin (IFL) in combination with either bevacizumab or placebo in a randomized phase III study. Following microdissection, tissue was subject to DNA sequencing to identify K-ras mutations in codons 12 and 13. Hazard ratios for the bevacizumab group relative to the control group were estimated from an unstratified Cox regression model. The median progression-free survival (PFS), OS times, and objective response rates were compared.

RESULTS

K-ras status was assessed in 230 patients (28.3%). The median PFS was significantly longer in bevacizumab-treated patients with wild-type (wt)- (13.5 versus 7.4 months; hazard ratio 0.44, p < .0001) and mutant (m)-K-ras (9.3 versus 5.5 months; hazard ratio 0.41, p = .0008). A significantly higher response rate for IFL plus bevacizumab was observed only in wt-K-ras patients (60.0% versus 37.3%, p = .006) compared with 43.2% versus 41.2% in the m-K-ras group.

CONCLUSION

Bevacizumab provides significant clinical benefit in patients with mCRC expressing either mutant or wild-type K-ras.

A randomized phase IIIB trial of chemotherapy, bevacizumab, and panitumumab compared with chemotherapy and bevacizumab alone for metastatic colorectal cancer

PURPOSE

Panitumumab, a fully human antibody targeting the epidermal growth factor receptor, is active in patients with metastatic colorectal cancer (mCRC). This trial evaluated panitumumab added to bevacizumab and chemotherapy (oxaliplatin- and irinotecan-based) as first-line treatment for mCRC.

PATIENTS AND METHODS

Patients were randomly assigned within each chemotherapy cohort to bevacizumab and chemotherapy with or without panitumumab 6 mg/kg every 2 weeks. The primary end point was progression-free survival (PFS) within the oxaliplatin cohort. Tumor assessments were performed every 12 weeks and reviewed centrally.

RESULTS

A total of 823 and 230 patients were randomly assigned to the oxaliplatin and irinotecan cohorts, respectively. Panitumumab was discontinued after a planned interim analysis of 812 oxaliplatin patients showed worse efficacy in the panitumumab arm. In the final analysis, median PFS was 10.0 and 11.4 months for the panitumumab and control arms, respectively (HR, 1.27; 95% CI, 1.06 to 1.52); median survival was 19.4 months and 24.5 months for the panitumumab and control arms, respectively. Grade 3/4 adverse events in the oxaliplatin cohort (panitumumab v control) included skin toxicity (36% v 1%), diarrhea (24% v 13%), infections (19% v 10%), and pulmonary embolism (6% v 4%). Increased toxicity without evidence of improved efficacy was observed in the panitumumab arm of the irinotecan cohort. KRAS analyses showed adverse outcomes for the panitumumab arm in both wild-type and mutant groups.

CONCLUSION

The addition of panitumumab to bevacizumab and oxaliplatin- or irinotecan-based chemotherapy results in increased toxicity and decreased PFS. These combinations are not recommended for the treatment of mCRC in clinical practice.

Fluorouracil, leucovorin, and oxaliplatin with and without cetuximab in the first-line treatment of metastatic colorectal cancer

PURPOSE

This randomized study assessed whether the best overall response rate (ORR) of cetuximab combined with oxaliplatin, leucovorin, and fluorouracil (FOLFOX-4) was superior to that of FOLFOX-4 alone as first-line treatment for metastatic colorectal cancer. The influence of KRAS mutation status was investigated.

PATIENTS AND METHODS

Patients received cetuximab (400 mg/m(2) initial dose followed by 250 mg/m(2)/wk thereafter) plus FOLFOX-4 (oxaliplatin 85 mg/m(2) on day 1, plus leucovorin 200 mg/m(2) and fluorouracil as a 400 mg/m(2) bolus followed by a 600 mg/m(2) infusion during 22 hours on days 1 and 2; n = 169) or FOLFOX-4 alone (n = 168). Treatment was continued until disease progression or unacceptable toxicity. KRAS mutation status was assessed in the subset of patients with assessable tumor samples (n = 233).

RESULTS

The confirmed ORR for cetuximab plus FOLFOX-4 was higher than with FOLFOX-4 alone (46% v 36%). A statistically significant increase in the odds for a response with the addition of cetuximab to FOLFOX-4 could not be established (odds ratio = 1.52; P = .064). In patients with KRAS wild-type tumors, the addition of cetuximab to FOLFOX-4 was associated with a clinically significant increased chance of response (ORR = 61% v 37%; odds ratio = 2.54; P = .011) and a lower risk of disease progression (hazard ratio = 0.57; P = .0163) compared with FOLFOX-4 alone. Cetuximab plus FOLFOX-4 was generally well tolerated.

CONCLUSION

KRAS mutational status was shown to be a highly predictive selection criterion in relation to the treatment decision regarding the addition of cetuximab to FOLFOX-4 for previously untreated patients with metastatic colorectal cancer.

Open-label phase I trial of vandetanib in combination with mFOLFOX6 in patients with advanced colorectal cancer

BACKGROUND

Vandetanib (ZACTIMA) is a once-daily oral inhibitor of vascular endothelial growth factor, epidermal growth factor and RET receptor tyrosine kinases. The safety and tolerability of vandetanib plus mFOLFOX6 was investigated in patients with advanced colorectal cancer (CRC).

METHODS

Patients eligible for first- or second-line chemotherapy received once-daily oral doses of vandetanib (100 or 300 mg) plus 14-day treatment cycles of mFOLFOX6.

RESULTS

Seventeen patients received vandetanib 100 mg (n = 9) or 300 mg (n = 8) plus mFOLFOX6. The protocol definition of a tolerable dose (vandetanib-related dose-limiting toxicity [DLT] in less than two patients) was met in both dose cohorts, with one DLT of diarrhoea reported in each. Overall, the most common adverse events were diarrhoea, nausea and lethargy (all n = 11). There was no pharmacokinetic interaction between vandetanib and mFOLFOX6. Preliminary efficacy results included one complete response and three confirmed partial responses.

CONCLUSIONS

In patients with advanced CRC, once-daily vandetanib (100 or 300 mg) with mFOLFOX6 was generally well tolerated.

From the podium to the patient: bringing the 2008 ASCO meeting to the clinic

Around 4,800 abstracts on preclinical and clinical research in different oncology areas were presented and discussed by oncology clinicians and scientists at the 44th American Society of Clinical Oncology meeting, the largest international forum in the field. As expected, the meeting provided valuable insights into future developments as well as enlightening clinicians regarding current controversies. This manuscript is an opinion-based review of the studies presented at the meeting, focusing on findings from randomized phase III trials and translational researches that, in the authors' opinion, are most likely to modify clinical practice or help scientists in designing future translational and clinical studies.