Effectors of epidermal growth factor receptor pathway: the genetic profiling ofKRAS, BRAF, PIK3CA, NRAS mutations in colorectal cancer characteristics and personalized medicine

Mutations in KRAS oncogene are recognized biomarkers that predict lack of response to anti- epidermal growth factor receptor (EGFR) antibody therapies. However, some patients with KRAS wild-type tumors still do not respond, so other downstream mutations in BRAF, PIK3CA and NRAS should be investigated. Herein we used direct sequencing to analyze mutation status for 676 patients in KRAS (codons 12, 13 and 61), BRAF (exon 11 and exon 15), PIK3CA (exon 9 and exon 20) and NRAS (codons12, 13 and 61). Clinicopathological characteristics associations were analyzed together with overall survival (OS) of metastatic colorectal cancer patients (mCRC). We found 35.9% (242/674) tumors harbored a KRAS mutation, 6.96% (47/675) harbored a BRAF mutation, 9.9% (62/625) harbored a PIK3CA mutation and 4.19% (26/621) harbored a NRAS mutation. KRAS mutation coexisted with BRAF, PIK3CA and NRAS mutation, PIK3CA exon9 mutation appeared more frequently in KRAS mutant tumors (P = 0.027) while NRAS mutation almost existed in KRAS wild-types (P<0.001). Female patients and older group harbored a higher KRAS mutation (P = 0.018 and P = 0.031, respectively); BRAF (V600E) mutation showed a higher frequency in colon cancer and poor differentiation tumors (P = 0.020 and P = 0.030, respectively); proximal tumors appeared a higher PIK3CA mutation (P<0.001) and distant metastatic tumors shared a higher NRAS mutation (P = 0.010). However, in this study no significant result was found between OS and gene mutation in mCRC group. To our knowledge, the first large-scale retrospective study on comprehensive genetic profile which associated with anti-EGFR MoAbs treatment selection in East Asian CRC population, appeared a specific genotype distribution picture, and the results provided a better understanding between clinicopathological characteristics and gene mutations in CRC patients.

Relationship between everolimus exposure and safety and efficacy: meta-analysis of clinical trials in oncology

BACKGROUND

In patients with solid tumours, daily everolimus dosing demonstrated dose proportionality and linear pharmacokinetics. A meta-analysis was conducted to characterise the relationship between everolimus Cmin and efficacy and safety and the effect of CYP3A4 and P-glycoprotein (PgP) substrate/inhibitor/inducer coadministration on everolimus trough concentration (Cmin).

METHODS

Individual patient data from five phase 2/3 studies, in which steady state, predose pharmacokinetic samples were taken from patients with solid tumours administered everolimus 10mg/day, were pooled.

FINDINGS

Efficacy and safety were evaluable for 945 and 938 patients, respectively. A 2-fold increase in everolimus Cmin increased the likelihood of tumour size reduction (odds ratio 1.40, 95% confidence interval (CI) 1.23-1.60), was associated with a trend for reduced risk of progression-free survival events (risk ratio [RR] 0.90, 95% CI 0.69-1.18) and increased the risk of grade ⩾3 pulmonary (RR 1.93, 95% CI 1.12-3.34), stomatitis (RR 1.49, 95% CI 1.05-2.10) and metabolic (RR 1.30, 95% CI 1.02-1.65) events. Coadministering everolimus with strong CYP3A4 and PgP inhibitors increased everolimus Cmin by 10% and 20%, respectively; coadministration with CYP3A4 inducers reduced Cmin by 7%.

INTERPRETATION

A 2-fold increase in everolimus Cmin was associated with improved tumour size reduction and increased risk of high-grade pulmonary, metabolic and stomatitis events.

FUNDING

Novartis Pharmaceuticals Corporation.

Targeted therapy-induced diarrhea: A review of the literature

PURPOSE OF RESEARCH

Revision of the literature on targeted therapy-induced diarrhea (TT-ID).

PRINCIPAL RESULTS

TT-ID is frequent; the mechanisms are mainly secretive, followed by ischemic or autoimmune ones. The duration of TT-ID is protracted over time. Its intensity is of grade G1-G3 but may be fatal in patients with diffuse colitis or on ipilimumab. However, no specific guidelines are available on management of different grades of TT-ID. Preventive measures with antibiotics, probiotics or activated charcoal should be further investigated. Loperamide is the first choice drug followed by octreotide. The role of corticosteroids is controversial.

CONCLUSION

Early assessment and management of TT-ID is essential to prevent the worsening of this side-effect, patients' hospitalization and dose reduction or oncological treatment discontinuation. Future research is needed to better understand the pathophysiological mechanisms of TT-ID and it should also be investigated whether a specific pharmacological and/or non pharmachological approach is indicated.

Therapeutic potential and adverse events of everolimus for treatment of hepatocellular carcinoma - systematic review and meta-analysis

Everolimus is an orally administrated mammalian target of rapamycin (mTOR) inhibitor. Several large-scale randomized controlled trials (RCTs) have demonstrated the survival benefits of everolimus at the dose of 10 mg/day for solid cancers. Furthermore, mTOR-inhibitor-based immunosuppression is associated with survival benefits for patients with hepatocellular carcinoma (HCC) who have received liver transplantation. However, a low rate of tumor reduction and some adverse events have been pointed out. This review summarizes the antitumor effects and adverse events of everolimus and evaluates its possible application in advanced HCC. For the meta-analysis of adverse events, we used the RCTs for solid cancers. The odds ratios of adverse events were calculated using the Peto method. Manypreclinical studies demonstrated that everolimus had antitumor effects such as antiproliferation and antiangiogenesis. However, some differences in the effects were observed among in vivo animal studies for HCC treatment. Meanwhile, clinical studies demonstrated that the response rate of single-agent everolimus was low, though survival benefits could be expected. The meta-analysis revealed the odds ratios (95% confidence interval [CI]) of stomatitis: 5.42 [4.31-6.73], hyperglycemia: 3.22 [2.37-4.39], anemia: 3.34 [2.37-4.67], pneumonitis: 6.02 [3.95-9.16], aspartate aminotransferase levels: 2.22 [1.37-3.62], and serum alanine aminotransferase levels: 2.94 [1.72-5.02], respectively. Everolimus at the dose of 10 mg/day significantly increased the risk of the adverse events. In order to enable its application to the standard conventional therapies of HCC, further studies are required to enhance the antitumor effects and manage the adverse events of everolimus.

Adverse reactions to targeted and non-targeted chemotherapeutic drugs with emphasis on hypersensitivity responses and the invasive metastatic switch

More than 100 drugs are used to treat the many different cancers. They can be divided into agents with relatively broad, non-targeted specificity and targeted drugs developed on the basis of a more refined understanding of individual cancers and directed at specific molecular targets on different cancer cells. Individual drugs in both groups have been classified on the basis of their mechanism of action in killing cancer cells. The targeted drugs include proteasome inhibitors, toxic chimeric proteins and signal transduction inhibitors such as tyrosine kinase (non-receptor and receptor), serine/threonine kinase, histone deacetylase and mammalian target of rapamycin inhibitors. Increasingly used targeted vascular (VEGF) and platelet-derived endothelial growth factor blockade can provoke a range of pathological consequences. Many of the non-targeted drugs are cytotoxic, suppressing haematopoiesis as well as provoking cutaneous eruptions and vascular, lung and liver injury. Cytotoxic side effects of the targeted drugs occur less often and usually with less severity, but they show their own unusual adverse effects including, for example, a lengthened QT interval, a characteristic papulopustular rash, nail disorders and a hand-foot skin reaction variant. The term hypersensitivity is widely used across a number of disciplines but not always with the same definition in mind, and the terminology needs to be standardised. This is particularly apparent in cancer chemotherapy where anti-neoplastic drug-induced thrombocytopenia, neutropenia, anaemia, vascular disorders, liver injury and lung disease as well as many dermatological manifestations sometimes have an immune basis. The most insidious of all adverse consequences of targeted therapies, however, are tumour adaptation, increased malignancy and the invasive metastatic switch seen with anti-angiogenic drugs that inhibit the VEGF-A pathway. Adverse reactions to 44 non-targeted and 33 targeted, frequently used, chemotherapeutic drugs are presented together with discussions of diagnosis, premedications, desensitizations and importance of understanding the mechanisms underlying the various drug-induced reactions. There is need for wide-ranging acceptance of what constitutes a hypersensitivity reaction and for allergists to be more involved in the diagnosis, treatment and prevention of chemotherapeutic drug-induced hypersensitivity reactions.

Critical appraisal of ramucirumab (IMC-1121B) for cancer treatment: from benchside to clinical use

Although antiangiogenic treatments have produced milestone advances in the treatment of several diseases, and have significantly extended the median survival of cancer patients, these agents share some weaknesses, including a limited impact on the overall cure rate, a fleeting effect because of redundant pathways or early appearance of resistance mechanisms, and the lack of predictive factors for treatment selection. Recent data suggest that antibodies targeting the vascular endothelial growth factor axis exert their activity through the inhibition of vascular endothelial growth factor receptor-2 phosphorylation, which has a pivotal role in the neoangiogenic process. Ramucirumab, a fully humanized monoclonal antibody specifically directed against the extracellular domain of the receptor, administered intravenously every 2 or 3 weeks, is emerging as a novel antiangiogenic opportunity. Starting with preclinical data and early clinical results, this concise review focuses on the development of the novel compound across multiple cancers (including gastrointestinal malignancies, breast cancer, lung carcinoma, and genitourinary tumors), and presents available data from randomized phase II and phase III trials. REGARD was the first phase III study to report on the efficacy of single-agent ramucirumab in patients with advanced cancer. Many other ongoing phase III trials are testing the efficacy of this interesting antiangiogenic compound as a single agent or in combination with chemotherapy in different cancer types.

Safety and efficacy of everolimus in gastrointestinal and pancreatic neuroendocrine tumors after (177)Lu-octreotate

Although (177)Lu-octreotate is an effective treatment for patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs), some patients will fail or develop disease progression necessitating further treatment. We examined whether the safety and efficacy of everolimus after prior treatment with (177)Lu-octreotate is different from the published safety profile of everolimus in GEP-NETs. In this multicenter study, 24 GEP-NET patients were included. Adverse events were assessed according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE), version 3.0. Tumor response was measured according to the Response Evaluation Criteria in Solid Tumors (RECIST), version 1.0. Major clinical adverse events (grade 3 or 4) during treatment with everolimus were hyperglycemia (20.8%), fatigue (8.3%), thrombocytopenia (8.3%), and elevated alanine transaminase levels (8.3%). By radiological review, there were four partial responses (16.7%), five patients (62.5%) with stable disease, and three patients (12.5%) with progressive disease. For two patients (8.3%), no data on tumor response were available. Median progression-free survival (PFS) was 13.1 months (95% CI, 11.5-21.2). Median PFS of the current study was longer when compared with the RADIANT-3 trial (13.1 vs 11.4 months) and shorter when compared with the RADIANT-1 trial (13.1 vs 16.7 months). In conclusion, the safety profile of everolimus is not influenced by previous treatment with peptide receptor radiotherapy.

Anti-angiogenic therapies for metastatic colorectal cancer: current and future perspectives

Colorectal cancer (CRC) is the fourth most commonly diagnosed cancer and the second leading cause of cancer death in both men and women in the United States, with about 142820 new cases and 50830 deaths expected in 2013. Metastatic disease (mCRC) remains a challenge for oncologists worldwide due to its potential comorbidities. Recently, chemotherapy regimens containing 5-fluorouracil, leucovorin, oxaliplatin and irinotecan combinations are a standard of care in the metastatic disease. Currently, biological therapies involving vascular endothelial growth factor and epidermal growth factor receptor pathways, such as bevacizumab and cetuximab, have emerged as good option for improving mCRC patient survival. Now, aflibercept plus standard chemotherapy has also been approved in second line regimen for mCRC patients. Our review will discuss novel biological drugs and their indications for mCRC patients and will bring future perspectives in this regard.

The ErbB/HER family of protein-tyrosine kinases and cancer

The human epidermal growth factor receptor (EGFR) family consists of four members that belong to the ErbB lineage of proteins (ErbB1-4). These receptors consist of a glycosylated extracellular domain, a single hydrophobic transmembrane segment, and an intracellular portion with a juxtamembrane segment, a protein kinase domain, and a carboxyterminal tail. Seven ligands bind to EGFR including epidermal growth factor and transforming growth factor α, none bind to ErbB2, two bind to ErbB3, and seven ligands bind to ErbB4. The ErbB proteins function as homo and heterodimers. The heterodimer consisting of ErbB2, which lacks a ligand, and ErbB3, which is kinase impaired, is surprisingly the most robust signaling complex of the ErbB family. Growth factor binding to EGFR induces a large conformational change in the extracellular domain, which leads to the exposure of a dimerization arm in domain II of the extracellular segment. Two ligand-EGFR complexes unite to form a back-to-back dimer in which the ligands are on opposite sides of the aggregate. Following ligand binding, EGFR intracellular kinase domains form an asymmetric homodimer that resembles the heterodimer formed by cyclin and cyclin-dependent kinase. The carboxyterminal lobe of the activator kinase of the dimer interacts with the amino-terminal lobe of the receiver kinase thereby leading to its allosteric stimulation. Downstream ErbB signaling modules include the phosphatidylinositol 3-kinase/Akt (PKB) pathway, the Ras/Raf/MEK/ERK1/2 pathway, and the phospholipase C (PLCγ) pathway. Several malignancies are associated with the mutation or increased expression of members of the ErbB family including lung, breast, stomach, colorectal, head and neck, and pancreatic carcinomas and glioblastoma (a brain tumor). Gefitinib, erlotinib, and afatinib are orally effective protein-kinase targeted quinazoline derivatives that are used in the treatment of ERBB1-mutant lung cancer. Lapatinib is an orally effective quinazoline derivative used in the treatment of ErbB2-overexpressing breast cancer. Trastuzumab, pertuzumab, and ado-trastuzumab emtansine, which are given intravenously, are monoclonal antibodies that target the extracellular domain and are used for the treatment of ErbB2-positive breast cancer; ado-trastuzumab emtansine is an antibody-drug conjugate that delivers a cytotoxic drug to cells overexpressing ErbB2. Cetuximab and panitumumab are monoclonal antibodies that target ErbB1 and are used in the treatment of colorectal cancer. Cancers treated with these targeted drugs eventually become resistant to them. The role of combinations of targeted drugs or targeted drugs with cytotoxic therapies is being explored in an effort to prevent or delay drug resistance in the treatment of these malignancies.

Regorafenib for gastrointestinal malignancies : from preclinical data to clinical results of a novel multi-target inhibitor

Intracellular signals for cancer cell growth, proliferation, migration, and survival are frequently triggered by protein tyrosine kinases (TKs). The possibility of disrupting core disease pathways has led to development and widespread clinical use of specific TK inhibitors that in the past decade have markedly changed treatment strategies and impacted on overall outcomes. However, intrinsic resistance may limit the benefit of these drugs, and multiple escape routes compensate for the inhibited signaling. The disruption of several points of the same pathway and the simultaneous interference with different intracellular oncogenic processes have both been recognized as valuable strategies to maximize the therapeutic potential of this class of agents. In this scenario, regorafenib has emerged as a novel, orally active, multitarget compound with potent activity against a number of angiogenic and stromal TKs, including vascular endothelial growth factor receptor 2 (VEGFR-2), tyrosine kinase with immunoglobulin-like and EGF-like domains 2 (TIE-2), fibroblast growth factor receptor 1 (FGFR-1), and platelet-derived growth factor receptor (PDGFR). Moreover, the drug has the capability of blocking KIT, RET and V600 mutant BRAF. Starting from interesting preclinical results, this review describes the clinical development of regorafenib in gastrointestinal malignancies, focusing on data derived from cutting edge clinical trials that have provided evidence of efficacy in pretreated patients with advanced colorectal cancer or gastrointestinal stromal tumors.

Factors influencing choice of chemotherapy in metastatic colorectal cancer (mCRC)

Management of metastatic colorectal cancer requires a multimodal approach and must be performed by an experienced, multidisciplinary expert team. The optimal choice of the individual treatment modality, according to disease localization and extent, tumor biology, and patient clinical characteristics, will be one that can maintain quality of life and long-term survival, and even cure selected patients. This review is an overview of the different therapeutic approaches available in metastatic colorectal cancer, for the purpose of defining personalized therapeutic algorithms according to tumor biology and patient clinical features.

Open-label, multicentre expansion cohort to evaluate imgatuzumab in pre-treated patients with KRAS-mutant advanced colorectal carcinoma

AIM

Imgatuzumab (GA201) is a novel anti-epidermal growth factor receptor (anti-EGFR) antibody glycoengineered for enhanced antibody-dependent cell-mediated cytotoxicity (ADCC). We investigated the efficacy of imgatuzumab in patients with EGFR-positive, KRAS-mutant advanced colorectal cancer.

METHODS

Patients received single-agent imgatuzumab (1400mg on day 1 and 8 followed by q2W) as third line therapy in an open-label, multicentre, non-randomised, expansion study. The primary end-point was tumour response. Pre- and on-treatment biopsies and blood samples were investigated for biomarkers related to imgatuzumab's believed mechanism of action (MoA).

RESULTS

25 patients were treated and the best overall response was stable disease occurring in 40% of patients at 8weeks, 24% at 16weeks and 8% (two patients) at 32weeks. Median overall survival was 9.3months (95% confidence interval (CI): 5.1-12.3). Treatment-related rash, hypomagnesaemia and infusion-related reactions were the most common adverse events. Comparison of pre- and post-treatment biopsies revealed that the number of tumour-infiltrating immune cells increased notably after one cycle of therapy (median compound immune reactive score of 1491 versus 898 cells/mm(3) at baseline), whereas the number of peripheral natural killer cells decreased. A potential association between baseline tumour immune infiltration and clinical efficacy was seen.

CONCLUSIONS

These data may suggest that the MoA of imgatuzumab involves ADCC-related immune effects in the tumour and is not limited to simple receptor blockade.

Phase II open-label study to assess efficacy and safety of lenalidomide in combination with cetuximab in KRAS-mutant metastatic colorectal cancer

This study aimed to assess the efficacy and safety of combination treatment with lenalidomide and cetuximab in KRAS-mutant metastatic colorectal cancer patients. This was a phase II multicenter, open-label trial comprising a safety lead-in phase (phase IIa) to determine the maximum tolerated dose, and a randomized proof of concept phase (phase IIb) to determine the response rate of lenalidomide plus cetuximab combination therapy. Phase IIa treatment comprised oral lenalidomide (starting dose 25 mg/day) and intravenous cetuximab (400 mg/m² followed by weekly 250 mg/m²) in 28-day cycles. In phase IIb patients were randomized to either the phase IIa treatment schedule of lenalidomide plus cetuximab combination therapy or lenalidomide 25 mg/day monotherapy. Eight patients were enrolled into phase IIa. One patient developed a dose-limiting toxicity and the maximum tolerated dose of lenalidomide was determined at 25 mg/day. Forty-three patients were enrolled into phase IIb proof of concept. Best response was stable disease in 9 patients and study enrollment was terminated prematurely due to lack of efficacy in both treatment arms and failure to achieve the planned response objective. The majority of adverse events were grade 1 and 2. In both phases, the adverse events most commonly attributed to any study drugs were fatigue, rash and other skin disorders, diarrhea, nausea, and stomatitis. Thirty-nine deaths occurred; none was related to study drug. The combination of lenalidomide and cetuximab appeared to be well tolerated but did not have clinically meaningful activity in KRAS-mutant metastatic colorectal cancer patients.

Trial Registration

Clinicaltrials.gov NCT01032291

Regorafenib: from bench to bedside in colorectal cancer

Colorectal cancer (CRC) remains the third cause of cancer-related mortality in the USA. Despite the advances in screening, many patients present with incurable metastatic disease. Chemotherapy forms the basis of treatment for patients with advanced disease. Angiogenesis is an important step in developing metastases and, therefore, blocking the VEGF pathway seems promising. The development of bevacizumab as a monoclonal antibody targeting the VEGF pathway improved progression-free survival and overall survival in the metastatic settings, with no improvement in disease-free or overall survival in the adjuvant settings. Small molecules such as tyrosine-kinase inhibitors have been long evaluated in metastatic CRC with disappointing results in improving outcome. Most recently, the CORRECT study has resulted in improved outcome in patients with metastatic CRC who were heavily pretreated when they received regorafenib.

Quality of life, resource utilisation and health economics assessment in advanced neuroendocrine tumours: a systematic review

Neuroendocrine tumours (NET) are often diagnosed at an advanced stage when the prognosis is poor for patients, who often experience diminished quality of life (QoL). As new treatments for NET become available, it is important to characterise the associated outcomes, costs and QoL. A comprehensive search was performed to systematically review available data in advanced NET regarding cost of illness/resource utilisation, economic studies/health technology assessment and QoL. Four rounds of sequential review narrowed the search results to 22 relevant studies. Most focused on surgical procedures and diagnostic tools and contained limited information on the costs and consequences of medical therapies. Multiple tools are used to assess health-related QoL in NET, but few analyses have been conducted to assess the comparative impact of available treatment alternatives on QoL. Limitations include English language and the focus on advanced NET; ongoing terminology and classification changes prevented pooled statistical analyses. This systematic review suggests a lack of comparative economic and outcomes data associated with NET treatments. Further research on disease costs, resource utilisation and QoL for patients with advanced NET is warranted.

Emerging therapies and latest development in the treatment of unresectable pancreatic neuroendocrine tumors: an update for clinicians

Pancreatic neuroendocrine tumors (pNETs) differ in their clinical behavior, presentation and prognosis based on their initial histological features and disease stage. While small resectable tumors can be treated surgically, metastatic and locally advanced disease carries a significant mortality and treatment options have been limited in terms of their efficacy. Streptozocin-based regimens were the only agents available before but recent advances have improved the armamentarium to treat pNETs. Newer chemotherapeutic agents such as temozolomide, somatostatin analogs and targeted therapies including everolimus and sunitinib are now available to treat these tumors. Several combination regimens with targeted therapies and newer agents such as pazopanib are being developed and tested in ongoing trials.

Aflibercept in the treatment of patients with metastatic colorectal cancer: latest findings and interpretations

Inhibition of angiogenesis is an established adjunct in the treatment of metastatic colorectal cancer. Bevacizumab, a monoclonal antibody that binds to vascular endothelial growth factor (VEGF) A, improves clinical outcomes when added to standard chemotherapy for metastatic colorectal cancer. Unfortunately, the development of resistance is inevitable, and novel therapeutic strategies are needed. Aflibercept is an intravenously administered fusion protein of the human vascular endothelial growth factor receptor 1 (VEGFR1) and VEGFR2 extracellular domains. This antiangiogenic agent binds to VEGF A, VEGF B, and placental growth factor 1 (PlGF1) and PlGF2 with high affinity and inhibits downstream signaling. Common side effects of single agent aflibercept are similar to other antiangiogenic drugs and include hypertension, proteinuria, fatigue, and headache. Recent clinical data regarding the efficacy of aflibercept with standard chemotherapy for metastatic colorectal cancer, associated adverse events, and future areas of research are reviewed.

Are Targeted Therapies a Consideration in Poorly Differentiated Neuroendocrine Tumors?

The close relationship between poorly differentiated NETs (PDNETs) and well or intermediately differentiated neuroendocrine tumors (NETs) is evidenced by the World Health Organization criteria for distinguishing these groups and by recognition by the National Comprehensive Cancer Network that octreotide therapy should be considered in some PDNETs. Based on the possible derivation from similar normal cells and the somewhat arbitrary World Health Organization distinction, particularly between intermediate and poorly differentiated NETs, it seems reasonable that future studies of targeted agents in the treatment of NETs should evaluate patients with PDNETs as well.

Comparative cost-effectiveness of bevacizumab-irinotecan-fluorouracil versus irinotecan-fluorouracil in first-line metastatic colorectal cancer

PURPOSE

To evaluate the cost-effectiveness of the addition of bevacizumab to the irinotecan-fluorouracil (Douillard regimen-CPT-FUFA-) in first-line treatment of metastatic colorectal cancer in a single-institution population.

METHODS

Controlled, nonrandomized retrospective observational study. Treatment-naïve metastatic colorectal cancer patients received CPT-FUFA (January 2000-December 2003; control group) and bevacizumab_CPT-FUFA (January 2007-December 2010; study group). Variables related to: patient, clinical response (number of disease progression or death events, progression-free survival) and treatment (antineoplastic dose reduction, incremental cost/treated patient associated with the addition of bevacizumab).

STATISTICAL ANALYSIS

median progression-free survival (Kaplan-Meier method), and hazard ratio (Cox regression). Survival curves were compared (Mantel-Haenszel test).

RESULTS

In all, 69 patients were included: 32 (57.2 years -95%CI: 54.0-60.5-, 65.6% men) in CPT-FUFA group and 37 (68.1 years - 95%CI: 65.5-70.7-, 78.4% men) in bevacizumab_CPT-FUFA group. The disease progression or death events were 29 (90.6%) in CPT-FUFA group and 34 (91.9%) in bevacizumab_CPT-FUFA group. Median progression-free survival was 10.1 months (95%CI: 7.1-12.2) in CPT-FUFA and 11.0 months (95%CI: 7.6-12.6) in bevacizumab_CPT-FUFA (hazard ratio = 1.22; 95%CI: 0.7-2.1). Dose reductions: irinotecan and fluorouracil 11% (range: 4-20) in 5/32 (15.6%) CPT-FUFA patients and 25% (range: 8-35) in 18/37 (48.6%) bevacizumab_CPT-FUFA patients; Bevacizumab 30% (range: 4-50) in 20/37 (54.1%) bevacizumab_CPT-FUFA patients. The incremental cost associated with the addition of bevacizumab was 12,696.5 (IC95%:10,860.8-14,532.1) euros/patient.

CONCLUSION

The addition of bevacizumab to the irinotecan-fluorouracil regimen, does not improve progression-free survival in our study population but increases costs per treated patient. These results potentially compromise the cost-effectiveness of the Bevacizumab_CPT-FUFA regimen.

Management of advanced colorectal cancer, Part 1

PURPOSE

Important developments in chemotherapy for advanced colorectal cancer over the past 15 years are reviewed, with an emphasis on the most recently published data from clinical trials of newer multidrug regimens, administration techniques, and dosing schedules.

SUMMARY

Eight agents are approved by the Food and Drug Administration (FDA) for use in treating patients with advanced colorectal cancer. Fluorouracil and leucovorin still constitute the foundation of most chemotherapy regimens for this population; combination fluorouracil-leucovorin therapy plus either irinotecan (the FOLFIRI regimen) or oxaliplatin (the FOLFOX regimen) are two firmly established first-line treatments shown to produce similar outcomes. In Phase III trials conducted over the past six to seven years, regimens of capecitabine plus oxaliplatin (CapeOx) were demonstrated to have clinical effectiveness comparable to that of FOLFOX therapy. Response rates of 35-55% and median overall survival of ≥20 months have been documented with some of the newer regimens. Research to define the optimal role of the three monoclonal antibody agents approved by FDA for use in managing advanced colorectal cancer is ongoing; bevacizumab has been shown to confer significant survival benefits when added to certain chemotherapy regimens, and other monoclonal antibodies (cetuximab and panitumumab) also appear to offer significant benefits in select patients as first- or second-line therapies.

CONCLUSION

Over the past 15 years, a shift toward multiagent treatment strategies including a variety of chemotherapy agents and monoclonal antibodies has yielded improved rates of response and prolonged survival among patients with advanced colorectal cancer. The CapeOx, FOLFOX, and FOLFIRI regimens are currently among the most widely used first-line treatments.

Focus on treatment of lung carcinoid tumor

Bronchial typical carcinoid tumors are neuroendocrine bronchopulmonary tumors with a low-grade malignancy, and an atypical carcinoid is an intermediate form of these tumors. There is a lack of knowledge on the optimal treatment for these tumors. The surgical treatment of choice consists of a lobectomy supplemented by dissection. The benefit of chemotherapy and radiotherapy is unclear. Targeted therapy could be used in this condition, but there is a lack of research recommending it.

Risk of hypertension with regorafenib in cancer patients: a systematic review and meta-analysis

BACKGROUND

Regorafenib is a novel multikinase inhibitor approved for use in metastatic colorectal cancer (mCRC) and locally advanced gastrointestinal stromal tumors (GISTs). Hypertension is one of the major adverse events of this agent, but to date the incidence and risk of hypertension with regorafenib have not been systematically investigated. We have conducted a systematic review and meta-analysis of published clinical trials to determine its overall incidence and risk.

METHODS

PubMed, Web of Science and abstracts presented at the American Society of Clinical Oncology annual meetings were searched to identify relevant studies published up to September 9, 2013. Eligible studies were prospective phase II or III clinical trials using regorafenib in cancer patients with data on hypertension available. The incidence and relative risk (RR) of hypertension were calculated using a random-effects model.

RESULTS

Data from a total of 1,069 patients (regorafenib n = 750; controls n = 319) from five clinical trials were included for analysis. The overall incidence of all-grade and high-grade hypertension were 44.4 % [95 % confidence interval (CI) 30.8-59.0 %) and 12.5 % (95 % CI 5.2-27.1 %), respectively. The use of regorafenib in cancer patients was associated with a significantly increased risk of all-grade (RR 3.76, 95 % CI 2.35-5.99) and high-grade (RR, 8.39, 95 % CI 3.10-22.71) hypertension. The risk might vary with tumor types (P = 0.000).

CONCLUSIONS

Patients with cancer receiving regorafenib have a significantly higher risk of developing hypertension. Close monitoring and appropriate management of this hypertension are strongly recommended.

Ziv-aflibercept (Zaltrap) for the treatment of metastatic colorectal cancer

OBJECTIVE

Review pharmacology, pharmacokinetics, efficacy, and safety of ziv-aflibercept in combination with FOLFIRI for treatment of metastatic colorectal cancer (mCRC) resistant to or progressed following oxaliplatin-containing regimens.

DATA SOURCES

Articles indexed in PubMed (1948-August 2013), TOXLINE (2001-August 2013), and Google Scholar as well as meeting abstracts were identified using the search terms ziv-aflibercept and colorectal cancer.

STUDY SELECTION AND DATA EXTRACTION

Available English-language articles

DATA SYNTHESIS

Ziv-aflibercept, a selective vascular endothelial growth factor antagonist, was evaluated as monotherapy for treatment of mCRC in a phase 2 study and added to FOLFIRI in a phase 3 trial. Patient response to ziv-aflibercept as monotherapy did not reach statistical significance. Results suggest that response to ziv-aflibercept treatment is not influenced by prior bevacizumab therapy. A phase 3 trial compared the safety and efficacy of ziv-aflibercept plus FOLFIRI with placebo plus FOLFIRI in patients with mCRC who experienced disease progression on an oxaliplatin-containing regimen. Patients in the ziv-aflibercept arm had a median overall survival of 13.5 months, versus 12.06 months for those receiving placebo (hazard ratio [HR] = 0.817, 95% CI = 0.713 to 0.937). Progression-free survival for patients receiving ziv-aflibercept was higher compared with placebo (HR = 0.758; 95% CI = 0.661 to 0.869). The most common adverse effects observed were anemia, diarrhea, and neutropenia.

CONCLUSIONS

Ziv-aflibercept is a safe and effective option in combination with FOLFIRI for the treatment of mCRC in patients who progress on oxaliplatin-containing therapy. Superiority over other antiangiogenic treatment has not been established.

Overexpression of membrane proteins in primary and metastatic gastrointestinal neuroendocrine tumors

BACKGROUND

Small bowel and pancreatic neuroendocrine tumors (SBNETs and PNETs) are rare tumors whose incidence is increasing. Drugs targeting the somatostatin receptor are beneficial in these tumors. To identify additional cell-surface targets, we recently found receptors and membrane proteins with gene expression significantly different from adjacent normal tissues in a small number of primary SBNETs and PNETs. We set out to validate these expression differences in a large group of primary neuroendocrine tumors and to determine whether they are present in corresponding liver and lymph node metastases.

METHODS

Primary SBNETs and PNETs, normal tissue, nodal, and liver metastases were collected and mRNA expression of six target genes was determined by quantitative PCR. Expression was normalized to GAPDH and POLR2A internal controls, and differences as compared to normal tissue were assessed by Welch's t test.

RESULTS

Gene expression was determined in 45 primary PNETs with 20 nodal and 17 liver metastases, and 51 SBNETs with 50 nodal and 29 liver metastases. Compared to normal tissue, the oxytocin receptor (OXTR) showed significant overexpression in both primary and metastatic SBNETs and PNETs. Significant overexpression was observed for MUC13 and MEP1B in PNET primary tumors, and for GPR113 in primary SBNETs and their metastases. SCTR and ADORA1 were significantly underexpressed in PNETs and their metastases. OXTR protein expression was confirmed by immunohistochemistry.

CONCLUSIONS

OXTR is significantly overexpressed relative to normal tissue in primary SBNETs and PNETs, and this overexpression is present in their liver and lymph node metastases, making OXTR a promising target for imaging and therapeutic interventions.

Developing an objective marker to optimize patient selection and predict survival benefit in early-phase cancer trials

BACKGROUND

Several prognostic indices have been devised to optimize patient selection for phase 1 oncology trials with no consensus as to the optimal score and none qualifying as a marker of treatment response.

METHODS

Multivariate predictors of overall survival (OS) were tested on 118 referred patients to develop the Hammersmith Score (HS). The score's ability to predict OS, progression-free survival (PFS), and 90-day mortality (90DM) was compared with other prognostic indices. Changes in HS were recalculated during treatment.

RESULTS

Albumin<35 g/L, lactate dehydrogenase>450 U/L, and sodium<135 mmol/L emerged as independent prognostic factors. These were used with equal weighting to devise the HS, a compound prognostic index ranging from 0 to 3. High (HS=2-3) score predicted worse OS (hazard ratio [HR]=6.5, P<.001), PFS (HR=2.8, P=.01), and 90DM (OR=9.0, P<.001). HS was a more accurate multivariate predictor of OS (HR=6.4, P<.001, C-index=0.72), PFS (HR=2.7, P=.03), and 90DM (area under the ROC curve 0.703) compared with other scores. Worsening of the HS during treatment predicted for shorter OS (P<.001). HS retained prognostic and predictive ability following external validation.

CONCLUSIONS

HS is a simple, validated index to optimize patient selection and predict survival benefit from phase 1 oncology treatments. Prospective validation is ongoing.

Pharmacokinetics, clinical indications, and resistance mechanisms in molecular targeted therapies in cancer

The strategy for discovery and development of new cancer drugs has shifted the field from cytotoxic agents to therapies that selectively target oncogenic drivers. In the last decade, a number of targeted cancer therapies have been discovered and proven effective in a variety of hematological and solid malignancies. In this article, we review clinical pharmacokinetic characteristics of the U.S. Food and Drug Administration-approved targeted therapies and provide an overview of key clinical trials that led to approval of these drugs. The major limiting factor of targeted treatment is the development of resistance. We describe general principles of resistance and specific, clinically confirmed mechanisms of resistance to several therapies in different malignancies.

Everolimus plus exemestane in postmenopausal patients with HR(+) breast cancer: BOLERO-2 final progression-free survival analysis

Introduction

Effective treatments for hormone-receptor-positive (HR⁺) breast cancer (BC) following relapse/progression on nonsteroidal aromatase inhibitor (NSAI) therapy are needed. Initial Breast Cancer Trials of OraL EveROlimus-2 (BOLERO-2) trial data demonstrated that everolimus and exemestane significantly prolonged progression-free survival (PFS) versus placebo plus exemestane alone in this patient population.

Methods

BOLERO-2 is a phase 3, double-blind, randomized, international trial comparing everolimus (10 mg/day) plus exemestane (25 mg/day) versus placebo plus exemestane in postmenopausal women with HR⁺ advanced BC with recurrence/progression during or after NSAIs. The primary endpoint was PFS by local investigator review, and was confirmed by independent central radiology review. Overall survival, response rate, and clinical benefit rate were secondary endpoints.

Results

Final study results with median 18-month follow-up show that median PFS remained significantly longer with everolimus plus exemestane versus placebo plus exemestane [investigator review: 7.8 versus 3.2 months, respectively; hazard ratio = 0.45 (95% confidence interval 0.38–0.54); log-rank P < 0.0001; central review: 11.0 versus 4.1 months, respectively; hazard ratio = 0.38 (95% confidence interval 0.31–0.48); log-rank P < 0.0001] in the overall population and in all prospectively defined subgroups, including patients with visceral metastases, patients with recurrence during or within 12 months of completion of adjuvant therapy, and irrespective of age. The incidence and severity of adverse events were consistent with those reported at the interim analysis and in other everolimus trials.

Conclusion

The addition of everolimus to exemestane markedly prolonged PFS in patients with HR⁺ advanced BC with disease recurrence/progression following prior NSAIs. These results further support the use of everolimus plus exemestane in this patient population. ClinicalTrials.gov #NCT00863655.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-013-0060-1) contains supplementary material, which is available to authorized users.

Oral multikinase inhibitor regorafenib for the treatment of patients with metastatic colorectal cancer

SUMMARY Regorafenib is an oral small molecule inhibitor of multiple kinases involved in pathogenic processes, such as oncogenesis, tumor angiogenesis and maintenance of the tumor microenvironment, whose efficacy has been recently demonstrated in the treatment of pretreated metastatic colorectal cancer patients. The introduction of regorafenib into clinical practice allows medical oncologists to offer a new line of therapy to patients who have already received all of the other available drugs. Nevertheless, some issues deserve to be further examined in order to improve our knowledge of this drug’s potentialities and to better integrate its use in the daily routine, including the evaluation of response beyond convential size-based response evaluation criteria in solid tumors, the identification of molecular predictors of benefit, and the investigation of the potential role of regorafenib in different settings and in combination with other agents.

Regorafenib effects on human colon carcinoma xenografts monitored by dynamic contrast-enhanced computed tomography with immunohistochemical validation

Objective

To investigate dynamic contrast-enhanced computed tomography for monitoring the effects of regorafenib on experimental colon carcinomas in rats by quantitative assessments of tumor microcirculation parameters with immunohistochemical validation.

Materials and Methods

Colon carcinoma xenografts (HT-29) implanted subcutaneously in female athymic rats (n = 15) were imaged at baseline and after a one-week treatment with regorafenib by dynamic contrast-enhanced computed tomography (128-slice dual-source computed tomography). The therapy group (n = 7) received regorafenib daily (10 mg/kg bodyweight). Quantitative parameters of tumor microcirculation (plasma flow, mL/100 mL/min), endothelial permeability (PS, mL/100 mL/min), and tumor vascularity (plasma volume, %) were calculated using a 2-compartment uptake model. Dynamic contrast-enhanced computed tomography parameters were validated with immunohistochemical assessments of tumor microvascular density (CD-31), tumor cell apoptosis (TUNEL), and proliferation (Ki-67).

Results

Regorafenib suppressed tumor vascularity (15.7±5.3 to 5.5±3.5%; p<0.05) and tumor perfusion (12.8±2.3 to 8.8±2.9 mL/100 mL/min; p = 0.063). Significantly lower microvascular density was observed in the therapy group (CD-31; 48±10 vs. 113±25, p<0.05). In regorafenib-treated tumors, significantly more apoptotic cells (TUNEL; 11844±2927 vs. 5097±3463, p<0.05) were observed. Dynamic contrast-enhanced computed tomography tumor perfusion and tumor vascularity correlated significantly (p<0.05) with microvascular density (CD-31; r = 0.84 and 0.66) and inversely with apoptosis (TUNEL; r = −0.66 and −0.71).

Conclusions

Regorafenib significantly suppressed tumor vascularity (plasma volume) quantified by dynamic contrast-enhanced computed tomography in experimental colon carcinomas in rats with good-to-moderate correlations to an immunohistochemical gold standard. Tumor response biomarkers assessed by dynamic contrast-enhanced computed tomography may be a promising future approach to a more personalized and targeted cancer therapy.

Antiproliferative effects of lanreotide autogel in patients with progressive, well-differentiated neuroendocrine tumours: a Spanish, multicentre, open-label, single arm phase II study

Background

Somatostatin analogues (SSAs) are indicated to relieve carcinoid syndrome but seem to have antiproliferative effects on neuroendocrine tumours (NETs). This is the first prospective study investigating tumour stabilisation with the long-acting SSA lanreotide Autogel in patients with progressive NETs.

Methods

This was a multicentre, open-label, phase II trial conducted in 17 Spanish specialist centres. Patients with well-differentiated NETs and radiologically confirmed progression within the previous 6 months received lanreotide Autogel, 120 mg every 28 days over ≤92 weeks. The primary endpoint was progression-free survival (PFS). Secondary endpoints were response rate, tumour biomarkers, symptom control, quality of life (QoL), and safety. Radiographic imaging was assessed by a blinded central radiologist.

Results

Of 30 patients included in the efficacy and safety analyses, 40% had midgut tumours and 27% pancreatic tumours; 63% of tumours were functioning. Median PFS time was 12.9 (95% CI: 7.9, 16.5) months, and most patients achieved disease stabilisation (89%) or partial response (4%). No deterioration in QoL was observed. Nineteen patients (63%) experienced treatment-related adverse events, most frequently diarrhoea and asthenia; only one treatment-related adverse event (aerophagia) was severe.

Conclusion

Lanreotide Autogel provided effective tumour stabilisation and PFS >12 months in patients with progressive NETs ineligible for surgery or chemotherapy, with a safety profile consistent with the pharmacology of the class.

Trial registration

ClinicalTrials.gov Identifier NCT00326469; EU Clinical Trial Register EudraCT no 2004-002871-18.

A phase 1 trial of imatinib, bevacizumab, and metronomic cyclophosphamide in advanced colorectal cancer

Background:

This phase 1 clinical trial was conducted to determine the safety, maximum-tolerated dose (MTD), and pharmacokinetics of imatinib, bevacizumab, and metronomic cyclophosphamide in patients with advanced colorectal cancer (CRC).

Methods:

Patients with refractory stage IV CRC were treated with bevacizumab 5 mg kg⁻¹ i.v. every 2 weeks (fixed dose) plus oral cyclophosphamide q.d. and imatinib q.d. or b.i.d. in 28-day cycles with 3+3 dose escalation. Response was assessed every two cycles. Pharmacokinetics of imatinib and cyclophosphamide and circulating tumour, endothelial, and immune cell subsets were measured.

Results:

Thirty-five patients were enrolled. Maximum-tolerated doses were cyclophosphamide 50 mg q.d., imatinib 400 mg q.d., and bevacizumab 5 mg kg⁻¹ i.v. every 2 weeks. Dose-limiting toxicities (DLTs) included nausea/vomiting, neutropaenia, hyponatraemia, fistula, and haematuria. The DLT window required expansion to 42 days (1.5 cycles) to capture delayed toxicities. Imatinib exposure increased insignificantly after adding cyclophosphamide. Seven patients (20%) experienced stable disease for >6 months. Circulating tumour, endothelial, or immune cells were not associated with progression-free survival.

Conclusion:

The combination of metronomic cyclophosphamide, imatinib, and bevacizumab is safe and tolerable without significant drug interactions. A subset of patients experienced prolonged stable disease independent of dose level.

Methods of overcoming treatment resistance in colorectal cancer

Metastatic colorectal cancer remains a lethal disease with a poor prognosis in the majority of patients. Multiple drug combinations have been developed in recent years that have significantly improved response rates and overall survival however resistance to these drugs is inevitable. Novel agents are currently being developed and participation in clinical trials should be encouraged. In the absence of other treatment options in a patient with good performance status, there is compelling evidence for re-challenging with previously administered agents in different combinations. The aim of this review is to discuss mechanisms of resistance and methods to overcome treatment resistance in patients with metastatic colorectal cancer who are refractory to 5-FU, irinotecan, oxaliplatin, cetuximab and bevacizumab therapy.

Combination of irinotecan and a platinum agent for poorly differentiated neuroendocrine carcinomas

Extrapulmonary poorly differentiated neuroendocrine carcinoma (PDNEC) is a rare and highly aggressive neoplasm for which the optimal chemotherapy remains unclear. The objective of this study was to evaluate the outcomes of patients with PDNEC treated with cisplatin and irinotecan (IP) and perform a review of the literature. From 2008 to 2012, patients with advanced PDNEC (Ki67≥20%) who received the IP combination were selected for analysis. Radiologic responses were determined through Response Evaluation Criteria In Solid Tumors criteria. Twenty-eight patients were included. The median age at diagnosis was 57 years and the most common presentation was pancreatic PDNEC. Twenty-five patients (89%) received chemotherapy with cisplatin and irinotecan and three received carboplatin and irinotecan. Forty-six percent of the patients achieved objective response and the median time to tumor progression was 3.7 months. The median overall survival was 11.7 months. Thirteen patients (46%) had treatment interruptions or dose reductions due to grade 3/4 toxicity. This retrospective cohort of advanced extrapulmonary PDNEC patients suggests that the IP combination is feasible and resulted in similar response rate and median survival to other treatments previously reported.

Continuum of care with anti-angiogenic therapies in metastatic colorectal cancer

Inhibition of tumor angiogenesis has emerged as an important therapeutic component in the management of metastatic colorectal cancer. Three anti-angiogenic agents are currently approved in this clinical setting: bevacizumab, ziv-aflibercept, and regorafenib. Bevacizumab, a monoclonal antibody that targets the angiogenesis-driving ligand vascular endothelial growth factor A (VEGF-A), is the only anti-angiogenic agent approved in first-line therapy for metastatic colorectal cancer, where it can be used in combination with intravenous 5-fluorouracil-containing chemotherapy regimens. In conjunction with second-line chemotherapies, bevacizumab also has anti-cancer activity, both for the management of metastatic colorectal cancer in patients who received it as a part of their first line therapy and for those who are naïve to it. Ziv-aflibercept also has demonstrated clinical activity in conjunction with the chemotherapeutic regimen FOLFIRI in the second line management of patients with metastatic colorectal cancer; it functions by binding VEGF-A to the vascular endothelial growth factor proteins VEGF-B and PIGF (placental growth factor). Regorafenib, which inhibits multiple tyrosine kinases, including the VEGF receptors, has proven clinical benefit in the management of patients with metastatic colorectal cancer refractory to all other therapies. For patients' whose cancers are refractory to all other therapies, there is also evidence for the use of bevacizumab with fluoropyrimidine monotherapy, but only in the bevacizumab-naïve patient subset. Presently, it is not clear if any one agent as more activity in a particular line of therapy than another, has greater efficacy when paired with a particular chemotherapy backbone, or if a particular patient subset is more likely to benefit from these agents. Given the present benefit and tolerance data, an anti-angiogenic agent should be considered in all lines of therapy in the management of metastatic colorectal cancer, with the evidence for the use of these agents in each specific line of therapy and in specific chemotherapeutic combinations driving agent selection.

Understanding and targeting resistance to anti-angiogenic therapies

Therapies targeting tumor angiogenesis are used in a variety of malignancies, however not all patients benefit from treatment and impact on tumor control may be transient and modest. Mechanisms of resistance to anti-angiogenic therapies can be broadly categorized into VEGF-axis dependent alterations, non-VEGF pathways, and stromal cell interactions. Complimentary combinations of agents that inhibit alternative mechanisms of blood vessel formation may optimize inhibition of angiogenesis and improve clinical benefit for patients. The purpose of this review is to detail the preclinical evidence for mechanisms of angiogenic resistance and provide an overview of novel therapeutic approaches exploiting these pathways.

Targeted therapies in colorectal cancer: surgical considerations

Colorectal cancer (CRC) is a leading worldwide health concern that is responsible for thousands of deaths each year. The primary source of mortality for patients with CRC is the development and subsequent progression of metastatic disease. The most common site for distant metastatic disease is the liver. Although patients with metastatic disease to the liver have several effective treatment options, the only one for cure remains surgical resection of the liver metastases. Historically, most patients with liver metastases have had unresectable disease, and only a small percentage of patients have undergone complete curative resection. However, improved systemic therapies have led to an evolution in strategies to treat metastatic CRC to the liver. Under most conditions the management of these patients remains complex; and as chemotherapy options and new targeted therapies continue to improve outcomes, it is clear that a multidisciplinary approach must be the foundation on which advanced surgical and medical techniques are employed. Here, in this review, we highlight the role of targeted therapies in the surgical management of patients with metastatic CRC to the liver.

The use of targeted therapies in pancreatic neuroendocrine tumours: patient assessment, treatment administration, and management of adverse events

Together with the use of novel oral targeted therapies, a multidisciplinary approach can be used to effectively treat patients with advanced pancreatic neuroendocrine tumours (pNETs). Here we review the integration of the oncology nurse to the newly developed oral treatment setting for patients with pNETs. From the outset, the nurse must be involved in various processes, including performance of baseline assessments (e.g. blood pathology, cardiac and lung function testing, patient history) and general medical observations, treatment administration, dietary guidance, evaluation of comorbidities, and review of concomitant medications. Patient education and establishment of a strong partnership in care before the start of pNET therapy ultimately increase treatment adherence and reduce potential toxicities. Regular review of general patient status and disease progression and continuous monitoring of adverse events also help enhance treatment outcomes and subsequently improve quality of life. Nurses' knowledge of agent-specific toxicities and prompt, proactive management is a critical aspect of care. In essence, as the pNET treatment landscape evolves, the role of the healthcare professional in overall patient care must shift accordingly.

The status of targeted agents in the setting of neoadjuvant radiation therapy in locally advanced rectal cancers

Radiotherapy has a longstanding and well-defined role in the treatment of resectable rectal cancer to reduce the historically high risk of local recurrence. In more advanced borderline or unresectable cases, where the circumferential resection margin (CRM) is breached or threatened according to magnetic resonance imaging (MRI), despite optimized local multimodality treatment and the gains achieved by modern high quality total mesorectal excision (TME), at least half the patients fail to achieve sufficient downstaging with current schedules. Many do not achieve an R0 resection. In less locally advanced cases, even if local control is achieved, this confers only a small impact on distant metastases and a significant proportion of patients (30-40%) still subsequently develop metastatic disease. In fact, distant metastases have now become the predominant cause of failure in rectal cancer. Therefore, increasing the intensity and efficacy of chemotherapy and chemoradiotherapy by integrating additional cytotoxics and biologically targetted agents seems an appealing strategy to explore-with the aim of enhancing curative resection rates and improving distant control and survival. However, to date, we lack validated biomarkers for these biological agents apart from wild-type KRAS. For cetuximab, the appearance of an acneiform rash is associated with response, but low levels of magnesium appear more controversial. There are no molecular biomarkers for bevacizumab. Although some less invasive clinical markers have been proposed for bevacizumab, such as circulating endothelial cells (CECS), circulating levels of VEGF and the development of overt hypertension, these biomarkers have not been validated and are observed to emerge only after a trial of the agent. We also lack a simple method of ongoing monitoring of 'on target' effects of these biological agents, which could determine and pre-empt the development of resistance, prior to radiological and clinical assessessments or even molecular imaging. These shortcomings probably explain our current relative lack of success in the arena of combining these agents with chemoradiation.

Status of targeted therapies in the adjuvant treatment of colon cancer

Colon cancer is the 4(th) most common malignancy with 80% of patients diagnosed with early stage disease that is potentially curable with surgery and the addition of adjuvant chemotherapy in select Stage II and all Stage III patients. Adjuvant chemotherapy with 5-flurouracil based regimens has been shown to have overall survival benefit in Stage III disease with some benefit shown in certain sub-populations in Stage II disease. In recent years, targeted therapies directed against vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EFGR) have shown improved survival in metastatic colon cancer. However, trials of these agents in the adjuvant setting showed no benefit. Reasons for failure of these agents in trials thus far include differences in the molecular biology of macrometastatic versus micrometastatic disease and the lack of biologic predictive markers to target the appropriate patient populations for these agents.

A review of cutaneous toxicities from targeted therapies in the treatment of colorectal cancers

Currently there are three targeted therapies approved for the treatment of colorectal cancers. These include the epidermal growth factor receptor (EGFR) inhibitors, cetuximab and panitumumab, and the multikinase inhibitor regorafenib. It is important to understand and recognize the common presentations of cutaneous toxicity that result from these agents to effectively manage symptoms and prevent premature discontinuation of anticancer treatment.

Using Molecular Markers to Guide Therapy of Metastatic Colorectal Cancer

Colorectal cancer remains one of the most commonly diagnosed cancers with almost one-fourth of patients presenting with metastatic disease at the time of diagnosis. As the repertoire of anticancer agents has expanded to treat colorectal patients with metastatic disease, life expectancies have increased and patients are remaining on therapy for longer periods of time. The exact way in which to combine chemotherapeutic and targeted agents remains a therapeutic challenge in an attempt to preserve efficacy while minimizing toxicity. A crucial need exists for reliable and reproducible biomarkers that can assist in personalizing the most advantageous therapy for patients based on the biology of their tumor that will prevent undue side effects and result in the longest duration of tumor stability. In this review, we discuss the completed studies for each agent currently approved for the treatment of metastatic colon cancer and emphasize a need for further prospective studies to solidify the use of biomarkers in this disease.

The role of personalized medicine in metastatic colorectal cancer: an evolving landscape

Advances in the treatment of metastatic colorectal cancer have led to an improvement in survival from 12 months with fluorouracil monotherapy to approximately 2 years. This is partly as a result of the addition of irinotecan and oxaliplatin, but is also due to the use of monoclonal antibodies against the epidermal growth factor receptor (EGFR) and antiangiogenic drugs such as bevacizumab. However, there are significant molecular differences between tumours which can affect both prognosis and response to treatment. Personalized medicine aims to tailor treatment according to the characteristics of the individual patient and is now a clinical reality as testing for KRAS mutations to guide treatment with the anti-EGFR monoclonal antibodies cetuximab and panitumumab is now part of routine clinical practice. However, not all patients who are KRAS wild type respond to anti-EGFR therapy and a validated biomarker for antiangiogenic therapy is still lacking. Therefore, other biomarkers are needed to assist with predicting response to both existing drugs as well as to drugs currently under investigation. This review summarizes the molecular biology of colorectal cancer, focusing on the genetic features that are currently most clinically relevant. Current and emerging biomarkers are reviewed along with their roles in selecting patients for targeted treatment with currently licensed therapies and drugs being evaluated in clinical trials. The value of predictive biomarkers of chemosensitivity and potential future treatment strategies are also discussed.