Angiogenesis is a multistep, complex and tightly regulated process that is necessary for tumor growth and metastasis. Based on data of preclinical models, several antiangiogenic compounds has been shown to modify activated tumor endothelium, which suggests that these compounds can improve cytotoxic drug delivery. Such agents have entered clinical trials as single agents or in combination with cytotoxic drugs, and have shown promising antitumor activity. The pharmacodynamic and pharmacokinetic characteristics of antiangiogenic drugs are reviewed here. Most of the early clinical testing of these agents was conducted in patients with advanced disease resistant to standard therapies. Phase III trials compared the efficacy of standard chemotherapy alone with standard chemotherapy in combination with an experimental angiogenesis inhibitor. Although some of these studies were negative or controversial, recent studies validated in large clinical trials with an anti-vascular endothelial growth factor antibody demonstrated significant clinical benefit and renewed enthusiasm for this therapeutic strategy. This review describes the clinical studies of antiangiogenic agents and highlights the challenges related to choosing appropriate strategies for the selection of patients, study design and choice of appropriate endpoints for the studies' development.
Angiogenesis is necessary for tumor growth. Drug discovery efforts have identified several potential therapeutic targets on endothelial cells and selective inhibitors capable of slowing tumor growth or producing tumor regression by blocking angiogenesis in in vivo tumor models. Certain antiangiogenic therapeutics increase the activity of cytotoxic anticancer treatments in preclinical models. More than 75 antiangiogenic compounds have entered clinical trials. Most of the early clinical testing was conducted in patients with advanced disease resistant to standard therapies. Several phase III trials have been undertaken to compare the efficacy of standard chemotherapy versus the same in combination with an experimental angiogenesis inhibitor. Preliminary results of the clinical studies suggest that single-agent antiangiogenic therapy is poorly active in advanced tumors. Although some of the results of combination trials are controversial, recent positive outcomes with an antivascular endothelial growth factor antibody combined with chemotherapy as front-line therapy of metastatic colorectal cancer have renewed enthusiasm for this therapeutic strategy. This article presents an overview of experimental and clinical studies of combined therapy with antiangiogenic agents and highlights the challenges related to the appropriate strategies for selection of the patients, study design, and choice of proper end points for preclinical and clinical studies using these agents.
Background State-of-the art therapy for recurrent ovarian cancer (ROC) suitable for platinum-based re-treatment includes bevacizumab-containing combinations (eg, carboplatin/paclitaxel, carboplatin/gemcitabine) or the most active non-bevacizumab regimen: carboplatin/pegylated liposomal doxorubicin (PLD). This head-to-head trial compared a standard bevacizumab-containing regimen versus carboplatin/PLD combined with bevacizumab. Methods In this multicentre, open-label, randomised, phase 3 trial, eligible patients had histologically confirmed epithelial ovarian, primary peritoneal, or fallopian tube carcinoma with first disease recurrence >6 months after first-line platinum-based chemotherapy, and were aged ≥18 years with Eastern Cooperative Oncology Group performance status 0-2. Patients were stratified by platinum-free interval, residual tumour, prior anti-angiogenic therapy, and study group language, and centrally randomised 1:1 using randomly permuted blocks of size two, four, or six to six intravenous cycles of carboplatin (AUC 4, day 1) plus gemcitabine (1000 mg/m 2 , days 1 and 8) every 3 weeks or six cycles of carboplatin (AUC 5, day 1) plus PLD (30 mg/m 2 , day 1) every 4 weeks, both given with bevacizumab (15 mg/kg every 3 weeks or 10 mg/kg every 2 weeks) until disease progression or toxicity. The primary endpoint was investigator-assessed progression-free survival (PFS). Efficacy data were analysed in the intention-to-treat population (all randomised patients). Safety was analysed in all patients who received at least one dose of study drug. This completed study is registered with ClinicalTrials.gov number NCT01837251.
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