Cediranib with mFOLFOX6 vs bevacizumab with mFOLFOX6 in previously treated metastatic colorectal cancer

Blood Vessel-Targeted Therapy in Colorectal Cancer: Current Strategies and Future Perspectives

The vasculature is a key player and regulatory component in the multicellular microenvironment of solid tumors and, consequently, a therapeutic target. In colorectal carcinoma (CRC), antiangiogenic treatment was approved almost 20 years ago, but there are still no valid predictors of response. In addition, treatment resistance has become a problem. Vascular heterogeneity and plasticity due to species-, organ-, and milieu-dependent phenotypic and functional differences of blood vascular cells reduced the hope of being able to apply a standard approach of antiangiogenic therapy to all patients. In addition, the pathological vasculature in CRC is characterized by heterogeneous perfusion, impaired barrier function, immunosuppressive endothelial cell anergy, and metabolic competition-induced microenvironmental stress. Only recently, angiocrine proteins have been identified that are specifically released from vascular cells and can regulate tumor initiation and progression in an autocrine and paracrine manner. In this review, we summarize the history and current strategies for applying antiangiogenic treatment and discuss the associated challenges and opportunities, including normalizing the tumor vasculature, modulating milieu-dependent vascular heterogeneity, and targeting functions of angiocrine proteins. These new strategies could open perspectives for future vascular-targeted and patient-tailored therapy selection in CRC.

Effectiveness of bevacizumab in the treatment of metastatic colorectal cancer: a systematic review and meta-analysis

OBJECTIVE

To evaluate the benefit of bevacizumab under the comprehensive treatment strategy and its advantages over other drugs, so as to provide reference for the formulation of clinical plans.

METHODS

As of October 1, 2022, the randomized controlled clinical trials of bevacizumab in combination with metastatic colorectal cancer published in PubMed, Cochrane Library and Medline databases were searched. The odds ratio (OR) and its 95% confidence interval (CI) were used to evaluate the short-term disease control effect and long-term survival of the treatment strategy.

RESULTS

21 RCTs (6665 patients; 3356 patients in the experimental group and 3309 patients in the control group; average age, 55-75 years) were treated with bevacizumab as the experimental group for metastatic colorectal cancer. BEV has stronger anti-tumor activity than the single treatment scheme (OR = 1.30, 95% CI: 1.11-1.52). And Benefits of the BEV group were 0.73 (0.55, 0.96), 1.26 (0.71, 2.24), 1.63 (0.92, 2.87) and 0.07 (0.02, 0.25) compared with CET, VAN, CED and PAN respectively. The disease control of BEV combined therapy was better (OR = 1.36, 95% CI: 1.04-1.78). The same as compared with cediranib (OR = 1.94, 95% CI: 1.06-3.55). However, the long-term prognosis of BEV, including the overall survival (HRs = 0.98, 95% CI: 0.84-1.15) and progression-free survival (HRs = 1.05,95% CI: 0.97-1.13) were not prolonged. The survival benefits of cetuximab and panitumumab were not reflected.

CONCLUSION

The addition of BEV can enhance the anti-tumor ability and disease control, while cetuximab and panitumumab may have stronger ability. However, it did not effectively improve the survival of patients. A more reasonable and effective treatment plan needs more clinical experimental support.

Risks of hypertension and thromboembolism in patients receiving bevacizumab with chemotherapy for colorectal cancer: A systematic review and meta-analysis

BACKGROUND

Guidelines show that for metastatic colorectal cancer (mCRC), a combination of three-drug regimens, fluorouracil, leucovorin, and oxaliplatin and bevacizumab (BVZ), is one of the first-line standard therapies. BVZ is generally well tolerated; however, it is associated with infrequent, life-threatening side effects such as severe hypertension (HTN) (5%-18%), Grade ≥3 arterial thromboembolism (ATE) (2.6%), Grade ≥3 hemorrhagic events (1.2%-4.6%), and gastrointestinal perforation (0.3%-2.4%). This meta-analysis aims to evaluate the additive risk of BVZ-induced severe HTN and thromboembolism when BVZ is combined with a standard chemotherapy regime in patients with mCRC.

METHODS

Our search was conducted from January 29, 2022, to February 22, 2022, through databases of PubMed, clinicaltrial.gov, EMBASE, Web of Science, and Cochrane Library. Data analysis from randomized controlled trials (RCTs) and clinical trials was conducted using Review Manager V.5.4, comparing BVZ-chemotherapy to chemotherapy only, focusing on cardiovascular AE such as HTN and arterial and venous thromboembolism.

RESULTS

The analysis from 26 clinical trials and RCTs showed that the odds of HTN were about four times higher, and ATE subgroup analysis of 11 studies showed over two times higher odds of ATE in patients being treated with BVZ compared to the chemotherapy-only group.

CONCLUSION

BVZ, when added to the standard chemotherapy regimen for mCRC, was associated with higher odds of developing HTN and thromboembolism, specifically ATE, than the chemotherapy-only group. Our findings are significant as they provide vital information in analyzing the risk-benefit ratio of adding BVZ to the standard chemotherapy regime in patients with mCRC, especially in patients with vascular comorbidities.

Clinical outcomes of chemotherapy-based therapies for previously treated advanced colorectal cancer: a systematic literature review and meta-analysis

PURPOSE

The purpose of this study was to evaluate clinical outcomes of standard therapies in previously treated, advanced colorectal cancer (CRC) patients.

METHODS

A systematic literature review was conducted in Embase, MEDLINE, and CENTRAL databases (January 2000-July 2021), annual oncology conferences (2019-2021), and clinicaltrials.gov to identify studies evaluating the use of licensed interventions in second-line or later settings. The primary outcome of interest was objective response rate (ORR) and secondary outcomes included progression-free survival (PFS) and overall survival (OS). ORR was pooled using the Freeman-Tukey double arcsine transformation. For survival outcomes, published Kaplan-Meier curves for OS and PFS were digitized to re-construct individual patient-level data and pooled following the methodology described by Combescure et al. (2014).

RESULTS

Twenty-three trials evaluating standard chemotherapies with or without targeted therapies across 4,791 advanced CRC patients contributed to our meta-analysis. In the second-line setting, the random effects pooled estimate of ORR was 22.4% (95% confidence interval (CI): 18.0, 27.1), median PFS was 7.0 months (95% CI: 6.4, 7.4), and median OS was 14.9 months (95% CI: 13.6, 16.1). In the third-line or later setting, the random effects pooled estimate of ORR was 1.7% (95% CI: 0.8, 2.7), median PFS was 2.3 months (95% CI: 2.0, 2.8), and median OS was 8.2 months (95% CI: 7.1, 9.1).

CONCLUSION

Standard treatments have limited efficacy in the second-line or later setting with worsening outcomes in later lines. Given the global burden of CRC, further research into novel and emerging therapeutic options following treatment failure is needed.

Phase IIIb study of the bevacizumab biosimilar candidate BI 695502 plus mFOLFOX6 in metastatic colorectal cancer

Aim: This study assessed the safety, efficacy, pharmacokinetics and immunogenicity of the bevacizumab biosimilar candidate BI 695502 plus mFOLFOX6 in patients with metastatic colorectal cancer (mCRC). Materials & methods: Patients with untreated mCRC received BI 695502 and chemotherapy (oxaliplatin, leucovorin and 5-fluorouracil). Primary end point: proportion of patients with prespecified adverse events (AEs). Results: Of 123 patients enrolled and treated, 58.5% experienced prespecified AEs. Median progression-free survival was 10.5 months, median overall survival was 19.4 months, and objective response rate was 61.0%. There were no antidrug antibody or neutralizing antidrug antibody-positive samples post-baseline. Trough BI 695502 plasma concentrations increased until cycle 9 and stabilized thereafter. Conclusion: BI 695502 has an acceptable safety and efficacy profile in the treatment of mCRC.

Trial Registration Number: NCT02776683 ( ClinicalTrials.gov ), 2015-003718-25 (EudraCT, European Clinical Trials Database https://www.clinicaltrialsregister.eu/ctr-search/search?query=2015-003718-25 )

Study name: Study 1302.3

Phase I study of cediranib, an oral VEGFR inhibitor, in combination with selumetinib, an oral MEK inhibitor, in patients with advanced solid malignancies

PURPOSE

Targeting the vascular endothelial growth factor (VEGF) pathway improves progression free survival in multiple advanced malignancies but durable responses are uncommon. Inhibition of the VEGF pathway at multiple levels of signal transduction may improve clinical outcomes. Preclinical data with cediranib, an inhibitor of all 3 VEGF receptors, in combination with selumetinib, an inhibitor of MEK 1/2, demonstrated improved tumor control experimentally. This phase I trial was designed to test the two agents in combination to evaluate the tolerability, safety and assess disease response.

METHODS

Patients with advanced solid malignancies were enrolled into this phase I trial. Cediranib and selumetinib were dosed using a toxicity-adaptive isotonic design for the dose escalation/de-escalation of each agent. Both cediranib and selumetinib were administered daily and continuously. Cycles were 28 days in length.

RESULTS

Eighteen patients were enrolled. At all dose levels, dose limiting toxicities (DLT) were observed, which limited dose escalation and further evaluation. The maximum tolerated dose of cediranib and selumetinib in combination could not be determined. The best response of stable disease was observed in eight patients.

CONCLUSIONS

Cediranib and selumetinib in combination on a continuous schedule was not tolerable, with patients experiencing cardiovascular and other DLTs. Intermittent schedules may be needed to establish a safe and tolerable combination of cediranib and selumetinib.

Angiogenesis Inhibitors for Colorectal Cancer. A Review of the Clinical Data

Since the late 1990s, therapy for metastatic colorectal cancer (mCRC) has changed considerably, and the combination of doublet or triplet chemotherapy and a targeted agent are now routinely used. The targeting of angiogenesis, the development of new blood vessels, represents a key element in the overall treatment strategy. Since the approval in 2004 of the first anti-angiogenetic drug, multiple agents have been approved and others are currently under investigation. We present an overview of the recent literature on approved systemic treatment of mCRC, with a focus on anti-angiogenic drugs, and current treatment approaches, and elaborate on the future role of angiogenesis in colorectal cancer as seen from a clinical perspective. The treatment of mCRC, in general, has changed from "one strategy fits all" to a more personalized approach. This is, however, not entirely the case for anti-angiogenetic treatments, partly due to a lack of validated biomarkers. The anti-angiogenetic standard treatment at the present primarily includes monoclonal antibodies. The therapeutic field of angiogenesis, however, has received increased interest after the introduction of newer combinations. These approaches will likely change the current treatment strategy, once again, to the overall benefit of patients.

Selective Vascular Endothelial Growth Factor Receptor Inhibitors Provide Limited Benefits for Metastatic Colorectal Cancer: A Meta-Analysis

BACKGROUND

Metastatic colorectal cancer (mCRC) is one of the most common and deadly cancers worldwide. For most patients diagnosed with mCRC and managed with 5-fluorouracil (5-FU)/leucovorin plus oxaliplatin (FOLFOX), the median survival time is still less than 2 years. Small molecule selective vascular endothelial growth factor receptor (VEGFR) inhibitors have been demonstrated to have strong anti-tumour activity in various cancer models.

OBJECTIVE

To demonstrate the efficacy and safety of selective VEGFR inhibitors in the management of mCRC.

METHODS

A comprehensive search in PubMed, EMBASE, Web of Science, Ovid MEDLINE, Google Scholar, Springer and Cochrane Central databases was performed for randomized controlled trials (RCTs) focusing on the effect of selective VEGFR inhibitors on mCRC. The primary outcome measures were progression-free survival (PFS) rates, overall survival (OS) rates, complete response (CR), partial response (PR), stable disease (SD), progressive disease (PD), objective response rates (ORRs), disease control rates (DCRs) and adverse effect (AE) rates. The dates of the included studies ranged from the inception of the database to January 15, 2020.

RESULTS

Twenty-two RCTs were included. A total of 9362 patients met the inclusion criteria. Compared with placebo, selective VEGFR inhibitors significantly increased the PFS rate, SD, PR and DCR, reduced PD, caused more treatment-emergent adverse events (TEAEs), hypertension, hand-foot skin reaction, diarrhoea, fatigue, and thrombocytopaenia and increased aspartate aminotransferase(AST) concentration. There was no significant difference between selective VEGFR inhibitors and placebo regarding OS rate, CR, ORR, proteinuria, hyperbilirubinaemia or alkaline phosphatase(ALP) concentration. Additionally, compared with FOLFOX4+placebo, FOLFOX4+ selective VEGFR inhibitors, clearly reduced PD, and caused more 3-4 AEs, serious AEs, hypertension, hand-foot syndrome, diarrhoea, nausea, vomiting, decreased appetite, dehydration, fatigue, dizziness, neutropaenia and thrombocytopaenia. For PFS rate, OS rate, CR, PR, SD, ORR, abdominal pain, peripheral sensory neuropathy, asthaenia, anaemia and hypokalaemia rates, there was no significant difference between FOLFOX4+ selective VEGFR inhibitors and FOLFOX4+placebo. However, compared with FOLFOX4+bevacizumab, FOLFOX4+selective VEGFR inhibitors, led to increased hypertension, neutropaenia, fatigue, thrombocytopaenia and asthaenia. There is no clear difference between FOLFOX4+selective VEGFR inhibitors and FOLFOX4+ bevacizumab with regard to PFS rate, OS rate, CR, PR, SD, PD, ORR, diarrhoea, nausea, vomiting, peripheral neuropathy and abdominal pain rates. Selective VEGFR inhibitors+cetuximab increased PFS and PR and reduced PD compared to cetuximab, but there was no statistical difference between the two groups for OS and SD.

CONCLUSION

Compared with placebo or cetuximab, selective VEGFR inhibitors alone or combined with cetuximab seemed to be more efficacious for mCRC respectively; however, the effects were not better than FOLFOX4 alone or when combined with bevacizumab for mCRC. Additionally, selective VEGFR inhibitors were not as safe as placebo or FOLFOX4 alone or in combination with bevacizumab in mCRC.

A network meta-analysis on the efficacy of sixteen targeted drugs in combination with chemotherapy for treatment of advanced/metastatic colorectal cancer

OBJECTIVE

A network meta-analysis was conducted comparing the short-term efficacies of 16 targeted drugs in combination with chemotherapy for treatment of advanced/metastatic colorectal cancer (CRC).

RESULTS

Twenty-seven RCTs were ultimately incorporated into this network meta-analysis. Compared with chemotherapy alone, bevacizumab + chemotherapy, panitumumab + chemotherapy and conatumumab + chemotherapy had higher PR rate. Bevacizumab + chemotherapy, cetuximab + chemotherapy, panitumumab + chemotherapy, trebananib + chemotherapy and conatumumab + chemotherapy had higher ORR rate in comparison to chemotherapy alone. Furthermore, bevacizumab + chemotherapy had higher DCR rate than chemotherapy alone. The results of our cluster analysis showed that chemotherapy combined with bevacizumab, cetuximab, panitumumab, conatumumab, ganitumab, or brivanib + cetuximab had better efficacies for the treatment of advanced/metastatic CRC in comparison to chemotherapy alone.

MATERIALS AND METHODS

Electronic databases were comprehensively searched for potential and related randomized controlled trials (RCTs). Direct and indirect evidence were incorporated for evaluation of stable disease (SD), progressive disease (PD), complete response (CR), partial response (PR), disease control rate (DCR) and overall response ratio (ORR) by calculating odds ratio (OR) and 95% confidence intervals (CI), and using the surface under the cumulative ranking curve (SUCRA).

CONCLUSIONS

These results indicated that bevacizumab + chemotherapy, panitumumab + chemotherapy, conatumumab + chemotherapy and brivanib + cetuximab + chemotherapy may have better efficacies for the treatment of advanced/metastatic CRC.

Combination adjuvant chemotherapy with targeted drugs for treatment of colorectal cancer: A network meta-analysis

Colorectal cancer (CRC) is one of the most fatal diseases in the world. The efficacy of present chemotherapy treatments are limited and the addition of targeted drugs have been put into practice. However, the preferred treatments among adjuvant chemotherapies still remain controversial and uncertain. To evaluate the efficacy of different adjuvant chemotherapies combined with or without targeted drugs to determine the optimal treatment for patients with CRC in clinical practice. PubMed and Embase were searched for eligible articles and only randomized controlled trials (RCTs) were included. R (Version 3.2.5) software was utilized to conduct the Bayesian network meta-analysis (NMA). Outcomes including overall survival (OS) and progression-free survival (PFS) were displayed using hazard ratios. And the rank probabilities of each treatment were evaluated using the surface under cumulative ranking curve. A total of 75 RCTs published after 1997 were included in the data analysis. Overall, FOLFIRI+ cetuximab was found to be the most effective treatment in terms of long-term survival and FOLFOX was the most effective pure chemotherapy treatment. The addition of targeted drugs will greatly improve the efficacy of chemotherapy. Targeted drug cetuximab combined with the chemotherapy regiment FOLFIRI is the preferable treatment for patients with CRC in clinical practice.

Antiangiogenic tyrosine kinase inhibitors in colorectal cancer: is there a path to making them more effective?

Antiangiogenic therapy has a proven survival benefit in metastatic colorectal cancer. Inhibition of the VEGF pathway using a variety of extracellular antibody approaches has clear benefit in combination with chemotherapy, while intracellular blockade using tyrosine kinase inhibitors (TKIs) such as sorafenib and regorafenib has had more limited success. Pharmacodynamic modeling using modalities such as DCE-MRI indicates potent antiangiogenic effects of these TKIs, yet numerous combination therapies, primarily with chemotherapy, have failed to demonstrate an additive benefit. The sole comparative study of a single agent TKI against placebo showed a survival benefit of regorafenib in patients with advanced, refractory disease. Preclinical data demonstrate synergy between antiantiogenic TKIs and targeted interventions including autophagy inhibition, and together with a renewed effort to define markers of susceptibility, such combinations may be a way to improve the limited efficacy of this once-promising drug class.

Surrogate Endpoints in Second-Line Trials of Targeted Agents in Metastatic Colorectal Cancer: A Literature-Based Systematic Review and Meta-Analysis

PURPOSE

The purpose of this study was to evaluate progression-free survival (PFS) and objective response rate (ORR) as surrogate endpoints of overall survival (OS) in modern clinical trials investigating the efficacy of targeted agents in the second-line treatment of metastatic colorectal cancer (mCRC).

MATERIALS AND METHODS

A systematic search of literature pertaining to randomized phase II and III trials evaluating targeted agents as second-line treatments for mCRC was performed. The strength of the correlation between both PFS and ORR and OS was assessed based on the Pearson's correlation coefficient (R) and the coefficient of determination (R2).

RESULTS

Twenty trials, including a total of 7,571 patients, met the search criteria. The median duration of post-progression survival (PPS) was 7.6 months. The median differences between experimental and control arms were 0.65 months (range, -2.4 to 3.4) for the median PFS and 0.7 months (range, -5.8 to 3.9) for the median OS. PFS and ORR showed moderate (R=0.734, R2=0.539, p < 0.001) and poor correlation (R=0.169, R2=0.029, p=0.476) with OS, respectively. No differences between anti-angiogenic agents and other drugs were evident.

CONCLUSION

Targeted agents investigated in the second-line treatment of mCRC provided minimal PFS gains translating into modest OS improvements. Considering both the moderate correlation between PFS and OS and the short duration of PPS, the OS should remain the preferred primary endpoint for randomized clinical trials in the second-line treatment of mCRC.

Angiogenesis inhibition in the second-line treatment of metastatic colorectal cancer: A systematic review and pooled analysis

The last two decades have seen intensive efforts devoted to the development of compounds that target angiogenesis for the treatment of metastatic colorectal cancer (mCRC). In this review, we describe supporting evidence and ongoing development of angiogenesis inhibitors in the second-line treatment of mCRC, and summarize relevant randomized trials to help therapeutic decision-making in daily practice.

Antiangiogenic therapy for refractory colorectal cancer: current options and future strategies

Even though significant improvements in the treatment of colorectal cancer (CRC) have been made in recent years, survival rates for metastatic colorectal cancer (mCRC) are poor. Effective treatment options for metastatic colorectal cancer remain limited, and new therapeutic strategies are desperately needed. Several tyrosine kinase inhibitors (TKIs) and monoclonal antibodies (mAbs) that target angiogenesis, a critical process for facilitating tumor cell growth, invasion, and metastasis, are either approved or in clinical development for the treatment of mCRC. Many of these agents have shown efficacy in mCRC, both as single agents and in combination with standard chemotherapy regimens. However, there is a need for predictive markers of response to identify those patients most likely to benefit from antiangiogenic therapy, and, to date, no markers of this type have been validated in patients. Additionally, because antiangiogenic agents typically cause cytostatic as opposed to cytotoxic antitumor effects, it is important to determine the best strategies for evaluating therapeutic response in mCRC to ensure maximum clinical benefit. In this review, we summarize the efficacy and tolerability of approved and investigational antiangiogenic agents for the treatment of mCRC. We also discuss potential markers of response to antiangiogenic agents and how these markers, along with appropriate endpoint selection, can improve clinical trial design.

The VEGFR Inhibitor Cediranib Improves the Efficacy of Fractionated Radiotherapy in a Colorectal Cancer Xenograft Model

BACKGROUND/PURPOSE

Radiotherapy (RT) increases local tumor control in locally advanced rectal cancer, but complete histological response is seen in only a minority of cases. Antiangiogenic therapy has been proposed to improve RT efficacy by "normalizing" the tumor microvasculature. Here, we examined whether cediranib, a pan-vascular endothelial growth factor (VEGF) receptor tyrosine kinase inhibitor, improves microvascular function and tumor control in combination with RT in a mouse colorectal cancer (CRC) model.

METHODS

CRC xenografts (HT29) were grown subcutaneously in mice. Animals were treated for 5 consecutive days with vehicle, RT (1.8 Gy daily), cediranib (6 mg/kg po), or combined therapy (cediranib 2 h prior to radiation). Tumor volume was measured with calipers. Vascular changes were analyzed by dynamic contrast-enhanced MRI, oxygenation and interstitial fluid pressure probes and histology. To investigate vascular changes more in detail, a second set of mice were fitted with titanium dorsal skinfold window chambers, wherein a HT29 tumor cell suspension was injected. In vivo fluorescence microscopy was performed before and after treatment (same treatment protocol).

RESULTS

In vivo microscopy analyses showed that VEGFR inhibition with cediranib led to a "normalization" of the vessel wall, with decreased microvessel permeability (p < 0.0001) and tortuosity (p < 0.01), and a trend to decreased vessel diameters. This seemed to lead to lower tumor hypoxia rates in the cediranib and combination groups compared to the control and RT groups. This led to an increased tumor control in the combination group compared to controls or monotherapy (p < 0.0001).

CONCLUSIONS

The combination of RT with cediranib enhances tumor control in a CRC xenograft mouse model. Microvascular analyses suggest that cediranib leads to vascular normalization and improved oxygenation.

Pharmacokinetic Aspects of Vascular Endothelial Growth Factor Tyrosine Kinase Inhibitors

Scientists have identified the impact of angiogenesis on tumor growth and survival. Among other efficient drugs, several small-molecule tyrosine kinase inhibitors (TKIs) targeting the vascular endothelial growth factor receptor (VEGFR) have been developed and have already been integrated into the treatment of various advanced malignancies. This review provides a compilation of current knowledge on the pharmacokinetic aspects of all VEGFR-TKIs already approved by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) and of those still under investigation. Additional information on substance metabolism, potential for drug-drug interactions (DDIs), and the need for dose adaptation in patients with predominant renal and/or hepatic impairment has been included. All TKIs introduced in this review were administered orally, allowing for easy drug handling for healthcare professionals and patients. For almost all substances, the maximum plasma concentrations were reached within a short period of time. The majority of the substances showed a high plasma protein binding and their excretion occurred via the feces and, to a lesser extent, via the urine. In most cases, dose adaptation in patients with mild to moderate renal or hepatic impairment is not recommended. Cytochrome P450 (CYP) 3A4 was found to play a crucial role in the drug metabolic processes of many compounds. In order to prevent unwanted DDIs, co-administration of VEGFR TKIs together with CYP3A4 inhibitors or inducers should be avoided. Throughout all TKIs, the data indicate high inter-individual variability. The causes of this are still unclear and require further research to allow for individualization of treatment regimens.

Thromboembolic Events Associated with Bevacizumab plus Chemotherapy for Patients with Colorectal Cancer: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Bevacizumab is a recombinant, humanized monoclonal antibody that hinders the proliferation of new blood vessels required for malignant progression. The drug is considered safe and tolerable; however, some controversy remains about whether it is linked to venous and arterial thromboembolic events (TEEs).

OBJECTIVE

To evaluate the risk for overall, venous, and arterial TEEs in patients with colorectal cancer (CRC) who are administered bevacizumab plus chemotherapy in randomized controlled trials (RCTs).

METHODS

We searched PubMed and CENTRAL databases to extract reports of relevant trials that were published in English between January 1, 2003, and December 31, 2014. All RCTs in which bevacizumab plus chemotherapy was compared with standard chemotherapy or with placebo plus chemotherapy for the treatment of CRC, and TEEs were reported, were included in a meta-analysis. Risk ratios (RRs) with 95% confidence intervals (CIs) of TEEs were calculated for each RCT. Because the between-study heterogeneities (I2) were insignificant, a fixed-effect model was used to determine the effect size of each TEE. A funnel plot was created to assess publication bias, and 2 forms of sensitivity analyses were performed for each outcome.

RESULTS

This meta-analysis included 22 RCTs with a total of 13,185 patients. Overall, compared with the control groups, patients with CRC who received bevacizumab were at significant risk for overall TEEs (RR, 1.334; 95% CI, 1.191-1.494; P <.001; I2 = 1.37%). Regarding venous TEEs, a significant risk was observed for patients who received bevacizumab versus control patients (RR, 1.244; 95% CI, 1.091-1.415; P = .001; I2 = 0.0%). Similarly, the risk for arterial TEEs was significant in bevacizumab-treated patients (RR, 1.627; 95% CI, 1.162-2.279; P = .005; I2 = 0.0%). Sensitivity analyses did not affect the level of significance of the effect size for each outcome, and no significant publication bias was observed.

CONCLUSION

In all the studies reviewed in this meta-analysis, the risk for venous or arterial TEEs was associated with bevacizumab use in patients with CRC. Healthcare providers are encouraged to consider thromboprophylaxis agents, periodically monitor their patients who receive bevacizumab, and carefully manage patients who are at increased risk for those complications.

Novel anti-angiogenic therapeutic strategies in colorectal cancer

INTRODUCTION

Anti-angiogenetic agents are currently the standard of care in metastatic CRC patients. Bevacizumab, aflibercept, regorafenib and recently ramucirumab have significantly improved both progression-free and overall survival in different lines of treatment. Since bevacizumab's approval, a number of novel anti-VEGF agents have been tested in preclinical and clinical models.

AREAS COVERED

This review is focused on the most recent clinical results of novel agents targeting VEGF and its receptors with a major focus on those investigated recently in clinical trials.

EXPERT OPINION

In the last 15 years, a number of new anti-angiogenetic agents have been tested. Unfortunately, most of them have demonstrated unacceptable toxicities or failed to show activity. When tested as single agents, encouraging preliminary results were reported with fruquintinib, famitinib, and nintedanib. Interesting novel mechanisms of action are also being explored: VGX-100 is a monoclonal antibody (mAb) which binds to VEGF-C, inhibiting activation of VEGFR-2 and VEGFR-3 when combined with bevacizumab; tanibirumab is a mAb which binds to VEGFR-2 and vanucizumab is a bispecific mAb binding both to VEGF-A and Angiopoietin-2. Data about the combination of these agents with chemotherapy are very encouraging, even though preliminary. However, the definition of specific predictive biomarkers remains a priority.

Pharmacokinetic and pharmacodynamic evaluation of aflibercept for the treatment of colorectal cancer

INTRODUCTION

Colorectal cancer (CRC) is currently one of the most lethal and prevalent tumors worldwide. Prognosis in the metastatic setting remains poor despite therapeutic advances. In addition to chemotherapy, new drugs have recently been developed targeting signaling pathways involved in tumor growth, differentiation and angiogenesis. Aflibercept , a recombinant protein derived from VEGF receptors 1 and 2, also targets this angiogenesis pathway but via a different mechanism, acting as VEGF decoy, thus blocking other VEGFs.

AREAS COVERED

A comprehensive review of preclinical studies with aflibercept in cell lines and xenografts of different tumor types is presented. Aflibercept safety, pharmacokinetics and pharmacodynamics data from Phase I studies in solid tumor patients are discussed. Implications of Phase II studies and the pivotal Phase III VELOUR trial of second-line treatment in metastatic CRC (mCRC) patients evaluating aflibercept alone or combined with chemotherapy are also described.

EXPERT OPINION

In this challenging field, aflibercept offers a good option for oxaliplatin-refractory mCRC patients when combined with irinotecan and 5-fluorouracil irrespective of prior anti-angiogenic treatment. Therapeutic management may be further advanced by characterization of patients with predictive biomarkers and molecular profiles to improve benefit with this treatment.

Vascular endothelial growth factor receptor tyrosine kinase inhibitors versus bevacizumab in metastatic colorectal cancer: A systematic review and meta-analysis

Bevacizumab has demonstrated a survival benefit in patients with metastatic colorectal cancer (mCRC) when combined with chemotherapy. Several randomized clinical trials comparing the efficacy and toxicity of vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors (TKIs) against bevacizumab have been reported. The present meta-analysis was conducted to identify the potentially significant benefit of the combined treatment regimens in patients with mCRC. PubMed, Embase and Cochrane Library databases were searched for the randomized controlled trials published on or before September 2014, which compared the efficacy and toxicity of VEGFR TKIs with bevacizumab in combination with chemotherapy in patients with mCRC. The primary endpoints included progression-free survival (PFS), overall survival (OS) and overall response rate (ORR), and secondary endpoints were the toxicity profiles. Relative risks (RRs) with 95% confidence intervals (CIs) for response rate and adverse events (AEs) were calculated, as well as hazard ratios (HRs) for PFS and OS. The final analysis included 4 studies comprising a total of 1,929 intent-to-treat patients with mCRC, which compared VEGFR TKIs (cediranib and axitinib) plus chemotherapy with bevacizumab plus chemotherapy. Results demonstrated that VEGFR TKIs plus chemotherapy significantly resulted in a modest but significantly shorter PFS [hazard ratio (HR), 1.12; 95% CI, 1.00-1.25; P=0.05] compared with that of bevacizumab plus chemotherapy but not in OS (HR, 1.10; 95% CI, 0.88-1.17; P=0.87) and ORR (RR, 0.95; 95% CI, 0.85-1.05; P=0.30). VEGFR TKIs treatment showed a less favorable AE profile compared with bevacizumab, with higher rates of grade-III/IV diarrhea, fatigue, hypertension, neutropenia and thrombocytopenia, whereas a higher incidence of peripheral neuropathy associated with the bevacizumab group was observed. In conclusion, the addition of VEGFR TKIs to chemotherapy resulted in a modest but significantly shorter PFS but not in OS and ORR compared with bevacizumab. The VEGFR TKIs group showed a less favorable AE profile with higher rates of diarrhea, fatigue, hypertension, neutropenia and thrombocytopenia, whereas a higher incidence of peripheral neuropathy associated with the bevacizumab was observed.

Novel Therapies in Development for Metastatic Colorectal Cancer

Colorectal cancer (CRC) is the second most common cause of cancer mortality in the United States. Despite advances in therapy, metastatic CRC remains lethal, and further improvements in therapy are needed. Growing understanding of cancer biology, particularly in growth factor signaling, angiogenesis, and cancer immunology, has translated into many novel therapies under investigation. Patients are increasingly selected for clinical trials rationally on the basis of integral biomarkers. This review discusses several promising agents in development for metastatic CRC.

Serum protein profiling reveals baseline and pharmacodynamic biomarker signatures associated with clinical outcome in mCRC patients treated with chemotherapy ± cediranib

Background:

This study evaluated soluble serum proteins as biomarkers to subset patients with metastatic colorectal cancer (mCRC) treated with chemotherapy±cediranib, a vascular endothelial growth factor (VEGF) signalling inhibitor (VEGFi). Exploring biomarkers at pre- and on-treatment may identify patient subgroups showing clinical benefit on cediranib combination.

Methods:

Two hundred and seven serum proteins were analysed in 588 mCRC patients at pre- and on-treatment with chemotherapy (FOLFOX/CAPOX)±cediranib 20 mg. Patients were enrolled in the phase III trial HORIZON II. We correlated baseline biomarker signatures and pharmacodynamic (PD) biomarkers with PFS and OS.

Results:

We identified a baseline signature (BS) of 47 biomarkers that included VEGFA, VEGFD, VEGFR2, VEGFR3 and TIE-2, which defined two distinct subgroups of patients. Patients treated with chemotherapy plus cediranib who had ‘high' BS had shorter PFS (HR=1.82, P=0.003) than patients with ‘low' BS. This BS did not correlate with PFS of the patients treated with chemotherapy plus placebo. In addition, we identified a profile of 16 PD proteins on treatment associated with PFS (HR=0.58, P<0.001) and OS (HR=0.52, P<0.001) in patients treated with chemotherapy plus cediranib. This PD profile did not correlate with PFS and OS in patients treated with chemotherapy plus placebo.

Conclusions:

Serum proteins may represent relevant biomarkers to predict the outcome of patients treated with VEGFi-based therapies. We report a BS and PD biomarkers that may identify mCRC patients showing increased benefit of combining cediranib with chemotherapy. These exploratory findings need to be validated in future prospective studies.

Lessons learned from adult clinical experience to inform evaluations of VEGF pathway inhibitors in children with cancer

Agents targeting the vascular endothelial growth factor (VEGF) pathway have been studied in adults with cancer for nearly two decades. It is important to assess the lessons learned from this adult experience and to see how these lessons can help inform pediatric development of agents in this class. The benefit achieved from the use of VEGF pathway targeted agents for adult cancers has primarily been to delay for several months disease progression and less commonly time to death for conditions in which cure is not a reasonable expectation. VEGF pathway targeted agents have shown no efficacy when applied in the adjuvant setting. For adults with advanced cancer, prolongation of survival by 2-3 months is considered an important achievement in some settings. However, the primary goal of pediatric oncology clinical research is to identify treatments that allow children to be cured of their cancer and to grow to adulthood without treatment-induced limitations that lower their quality of survival. An important question for the pediatric oncology research community, pharmaceutical companies, and regulatory agencies to address in planning for future clinical trials is whether existing data support a role for VEGF pathway targeted agents in contributing to a therapeutic pathway to cure for children with cancer.

Risk of cardiovascular toxicities in patients with solid tumors treated with sunitinib, axitinib, cediranib or regorafenib: an updated systematic review and comparative meta-analysis

BACKGROUND

We performed a systematic review and comparative meta-analysis of cardiovascular toxicities associated with sunitinib, axitinib, cediranib or regorafenib; oral multi tyrosine kinase inhibitors.

PATIENTS AND METHODS

Eligible studies included randomized phase II and III trials of patients with solid tumors on sunitinib, axitinib, cediranib or regorafenib describing daily events of hypertension, left ventricular dysfunction, bleeding or thrombosis.

RESULTS

Patients treated with these four agents had a significantly increased risk of all-grade hypertension and bleeding. The RR of all-grade hypertension, bleeding, thrombosis and cardiac dysfunction were 2.78 (95% CI 2.03-3.81; p<0.00001), 1.93 (95% CI 1.41-2.64; p<0.00001), 0.85 (95% CI 0.60-1.19; p=0.50), 2.36 (95% CI 0.95-5.87; p=0.06), respectively. Exploratory subgroup analysis showed no effect of the agent used (sunitinib vs. axitinib vs. cediranib) in the risk of hypertension; while for bleeding, only the sunitinib subgroup RR was significant compared to axitinib or cediranib.

CONCLUSIONS

Our meta-analysis has demonstrated that sunitinib, axitinib, cediranib and regorafenib are associated with a higher risk of developing all grade and high grade hypertension compared with control. While for bleeding, only the sunitinib subgroup RR was significant compared to axitinib or cediranib. Clinicians should be aware of these risks and perform regular cardiovascular monitoring.

When is a seamless study desirable? Case studies from different pharmaceutical sponsors

BACKGROUND

Inferentially seamless studies are one of the best-known adaptive trial designs. Statistical inference for these studies is a well-studied problem. Regulatory guidance suggests that statistical issues associated with study conduct are not as well understood. Some of these issues are caused by the need for early pre-specification of the phase III design and the absence of sponsor access to unblinded data. Before statisticians decide to choose a seamless IIb/III design for their programme, they should consider whether these pitfalls will be an issue for their programme.

METHODS

We consider four case studies. Each design met with varying degrees of success. We explore the reasons for this variation to identify characteristics of drug development programmes that lend themselves well to inferentially seamless trials and other characteristics that warn of difficulties.

RESULTS

Seamless studies require increased upfront investment and planning to enable the phase III design to be specified at the outset of phase II. Pivotal, inferentially seamless studies are unlikely to allow meaningful sponsor access to unblinded data before study completion. This limits a sponsor's ability to reflect new information in the phase III portion.

CONCLUSIONS

When few clinical data have been gathered about a drug, phase II data will answer many unresolved questions. Committing to phase III plans and study designs before phase II begins introduces extra risk to drug development. However, seamless pivotal studies may be an attractive option when the clinical setting and development programme allow, for example, when revisiting dose selection.

Risks of proteinuria associated with vascular endothelial growth factor receptor tyrosine kinase inhibitors in cancer patients: a systematic review and meta-analysis

BACKGROUND

Vascular endothelial growth factor tyrosine-kinase inhibitors (VEGFR-TKIs) have emerged as an effective targeted therapy in the treatment of cancer patients, the overall incidence and risk of proteinuria associated these drugs is unclear. We performed a systematic review and meta-analysis of published clinical trials to quantify the incidence and risk of proteinuria associated with VEGFR-TKIs.

METHODOLOGY

Databases from PubMed, Web of Science and abstracts presented at ASCO meeting up to May 31, 2013 were searched to identify relevant studies. Eligible studies included prospective phase II and III trials evaluating VEGFR-TKIs in cancer patients with adequate data on proteinuria. Statistical analyses were conducted to calculate the summary incidence, Odds ratio (OR) and 95% confidence intervals (CIs) by using either random effects or fixed effect models according to the heterogeneity of included studies.

PRINCIPAL FINDINGS

A total of 6,882 patients with a variety of solid tumors from 33 clinical trials were included in our analysis. The incidence of all-grade and high-grade (grade 3 or higher) proteinuria was 18.7% (95% CI, 13.3%-25.6%) and 2.4% (95% CI, 1.6%-3.7%), respectively. Patients treated with VEGFR-TKIs had a significantly increased risk of all-grade (OR 2.92, 95%CI: 1.09-7.82, p = 0.033) and high-grade proteinuria (OR 1.97, 95%CI: 1.01-3.84, p = 0.046) when compared to patients treated with control medication. No evidence of publication bias was observed.

CONCLUSIONS

The use of VEGFR-TKIs is associated with a significant increased risk of developing proteinuria. Physicians should be aware of this adverse effect and should monitor cancer patients receiving VEGFR-TKIs.

Intermittent dosing of axitinib combined with chemotherapy is supported by (18)FLT-PET in gastrointestinal tumours

Background:

We evaluated week-on/week-off axitinib dosing plus chemotherapy in patients with gastrointestinal tumours, including tumour thymidine uptake by fluorine-18 3′-deoxy-3′-fluorothymidine positron emission tomography (¹⁸FLT-PET).

Methods:

During a lead-in period, patients received twice daily (b.i.d.) axitinib 7 mg (n=3) or 10 mg (n=18) for 7 days followed by a 7-day dosing interruption; serial ¹⁸FLT-PET scans were performed before day 1 and on days 7, 10, and 14. Axitinib plus FOLFIRI or FOLFOX was then administered in 2-week cycles; axitinib was interrupted on day 10 of each cycle for 7 days.

Results:

The maximum tolerated dose of axitinib was 10 mg b.i.d., in a week-on/week-off schedule, combined with FOLFIRI or FOLFOX. Common all-causality grade 3 adverse events were neutropenia (38%), hypertension (33%), and fatigue (29%). Of 21 patients, 2 (10%) had a partial response and 12 (57%) had stable disease. Following 7 days of continuous axitinib dosing, tumour ¹⁸FLT uptake decreased –49% from baseline and recovered to –28% and –17% from baseline, respectively, after 3 and 7 days of axitinib interruption.

Conclusion:

Axitinib administered in a week-on/week-off schedule combined with FOLFIRI or FOLFOX is supported by ¹⁸FLT-PET data and was well tolerated in patients with gastrointestinal tumours.

Protein kinase inhibitors in metastatic colorectal cancer. Let's pick patients, tumors, and kinase inhibitors to piece the puzzle together!

INTRODUCTION

Increased understanding in intracellular signaling pathways leading to carcinogenesis, proliferation, migration, invasion, angiogenesis, and anti-apoptosis of colorectal cancer cells has been critical for target identification and drug development. Specific protein kinase inhibitors (KIs) have been developed to block activated pathways associated with tumor growth and progression. Although showing promising activity in preclinical models, until now, the majority of KIs were not able to demonstrate clinically meaningful efficacy in Phase II/III trials.

AREAS COVERED

The major pathways altered in colorectal cancer will be highlighted, and molecularly defined targets will be discussed. The mechanisms of action and the proof of principle demonstrated in preclinical models of KIs and the disappointing efficacy in clinical trials will be reviewed.

EXPERT OPINION

Despite recent negative study results, KIs have the potential to be the next class of therapeutics in the treatment of metastatic colorectal cancer. Molecular classification of the individual tumors and identification of molecular escape mechanisms for primary (intrinsic) and secondary resistances to KI treatment is critical to select the patients' most likely to benefit. Appropriate drug combinations based on those mechanisms of resistance have to be tested in selected patient populations to ensure progress and efficacy with the goal to lead to a clinically meaningful prolongation of patients' lives.

Angiogenic inhibitors for older patients with advanced colorectal cancer: Does the age hold the stage?

Although major progress has been achieved in the treatment of advanced colorectal cancer (CRC) with the employment of antiangiogenic agents, several questions remain on the use of these drugs in older patients. Since cardiovascular, renal and other comorbidities are common in the elderly, an accurate assessment of the patients’ conditions should be performed before a treatment decision is made. Since most CRC patients enrolled in clinical trials testing antiangiogenic drugs were aged < 65 years, the efficacy and tolerability of these agents in elderly patients has not been adequately explored. Data suggest that patients with advanced CRC derive similar benefit from bevacizumab treatment regardless of age, but the advantage of other antiangiogenic drugs in the same class of patients appears more blurred. Literature data suggest that specific antiangiogenic-related toxicities such as hypertension or arterial thromboembolic events may be higher in the elderly than in the younger patients. In addition, it should be emphasized that the patients included in the clinical studies discussed herein were selected and therefore may not be representative of the usual elderly population. Advanced age alone should not discourage the use of bevacizumab. However, a careful patients’ selection and watchful monitoring of toxicities are required to optimize the use of antiangiogenics in this population.