Maximizing the potential of bevacizumab in cancer treatment

Efficacy and safety of neoadjuvant bevacizumab plus chemotherapy in locally advanced gastric cancer patients: a retrospective, comparative study

OBJECTIVE

The clinical benefits of neoadjuvant bevacizumab plus chemotherapy in locally advanced gastric cancer patients are controversial. This study intended to evaluate the efficacy and safety of neoadjuvant bevacizumab plus chemotherapy in these patients.

METHODS

In this retrospective study, 71 locally advanced gastric cancer patients receiving neoadjuvant bevacizumab plus chemotherapy or neoadjuvant chemotherapy alone were divided into bevacizumab plus chemo group (N = 23) and chemo group (N = 48).

RESULTS

Objective response rate (52.2% vs. 35.4%), disease control rate (91.3% vs. 81.3%), surgical resection rate (95.7% vs. 85.4%), R0 resection rate (87.0% vs. 75.0%), and the proportion of patients with tumor regression grade 0-1 (31.8% vs. 17.1%) tended to increase in bevacizumab plus chemo group versus chemo group, although there was no statistical significance. The 48-month progression-free survival (PFS) rates were 58.3% and 33.4% in bevacizumab plus chemo group and chemo group. The 48-month overall survival (OS) rates were 65.1% and 46.5% in bevacizumab plus chemo group and chemo group, respectively. PFS tended to ascend, but OS did not vary in bevacizumab plus chemo group versus chemo group. Bevacizumab plus chemo (vs. chemo) independently related to longer PFS [hazard ratio (HR) = 0.263, P = 0.015], but not OS (HR = 0.207, P = 0.056) in locally advanced gastric cancer patients. The incidence of grade 3-4 adverse events did not vary between groups (all P > 0.05).

CONCLUSION

Neoadjuvant bevacizumab plus chemotherapy achieves higher treatment response and longer survival to some extent, with tolerable adverse events versus neoadjuvant chemotherapy alone in locally advanced gastric cancer patients, but its application needs further verification.

Development of a liquid chromatography-based versatile bioanalysis for bevacizumab based on pretreatment combining aptamer affinity purification and centrifugal ultrafiltration concentration

We report on the development of a versatile and accurate bioanalytical method for bevacizumab using a pretreatment method combining affinity purification with anti-idiotypic DNA aptamers and centrifugal ultrafiltration concentration, followed by liquid chromatography (LC)-fluorescence analysis. An affinity purification method using Sepharose beads as an affinity support removed immunoglobulin G and a large amount of coexisting substances in the serum sample. Purified bevacizumab was separated as a single peak by conventional LC and detected fluorometrically, showing good linearity (R2 = 0.999) in the range of 5-200 μg/mL, sufficient to analyze bevacizumab concentrations in the blood of bevacizumab-treated patients. By combining this purification method with a concentration method using a centrifugal filtration device that inhibits non-specific adsorption of bevacizumab, the quantitative range was reduced by a factor of 10 while showing good linearity (R2 = 0.999) in the 0.5-20 μg/mL range. The developed analytical method is expected to be used not only for general bioanalysis of therapeutic mAbs in clinical settings, but also for next-generation antibody drugs that show drug efficacy at low concentrations and for analysis of trace samples.

Development of a DNA aptamer that binds to the complementarity-determining region of therapeutic monoclonal antibody and affinity improvement induced by pH-change for sensitive detection

Therapeutic monoclonal antibodies (mAbs) are successful biomedicines; however, evaluation of their pharmacokinetics and pharmacodynamics demands highly specific discrimination from human immunoglobulin G naturally present in the blood. Here, we developed a novel anti-idiotype aptamer (termed A14#1) with extraordinary specificity against the anti-vascular endothelial growth factor therapeutic mAb, bevacizumab. Structural analysis of the antibody-aptamer complex showed that several bases of A14#1 recognized only the complementarity determining region (CDR) of bevacizumab, thereby contributing to its extraordinary specificity. As the CDR of bevacizumab is predicted to be highly positively charged under mildly acidic conditions and that DNA is negatively charged, the affinity of A14#1 to bevacizumab markedly increased at pH 4.7 (K_D = 44 pM) than at pH 7.4 (K_D = 12 nM). A14#1-based electrochemical detection method capable of detecting 31 pM of bevacizumab at pH 4.7 was thus developed. A14#1 could be potentially useful for therapeutic drug measurement as a novel ligand of bevacizumab.

From antibodies to living drugs: Quo vadis cancer immunotherapy?

In the last few decades, monoclonal antibodies targeting various receptors and ligands have shown significant advance in cancer therapy. However, still a great percentage of patients experiences tumor relapse despite persistent antigen expression. Immune cell therapy with adoptively transferred modified T cells that express chimeric antigen receptors (CAR) is an engaging option to improve disease outcome. Designer T cells have been applied with remarkable success in the treatment for acute B cell leukemias, yielding unprecedented antitumor activity and significantly improved overall survival. Relying on the success of CAR T cells in leukemias, solid tumors are now emerging potential targets; however, their complexity represents a significant challenge. In preclinical models, CAR T cells recognized and efficiently killed the wide spectrum of tumor xenografts; however, in human clinical trials, limited antitumor efficacy and serious side effects, including cytokine release syndrome, have emerged as potential limitations. The next decade will be an exciting time to further optimize this novel cellular therapeutics to improve effector functions and, at the same time, keep adverse events in check. Moreover, we need to establish whether gene-modified T cells which are yet exclusively used for cancer patients could also be successful in the treatment for other diseases. Here, we provide a concise overview about the transition from monoclonal antibodies to the generation of chimeric antigen receptor T cells. We summarize lessons learned from preclinical models, including our own HER2-positive tumor models, as well as from clinical trials worldwide. We also discuss the challenges we are facing today and outline future prospects.

Population pharmacokinetic analysis of phase 1 bemarituzumab data to support phase 2 gastroesophageal adenocarcinoma FIGHT trial

Purpose

To report population pharmacokinetic (PK) analysis of the phase 1 study (FPA144-001, NCT02318329) and to select a clinical dose and schedule that will achieve an empirical target trough concentration (C_trough) for an anti-fibroblast growth factor receptor 2b antibody, bemarituzumab.

Methods

Nonlinear mixed-effect modeling was used to analyse PK data. In vitro binding affinity and receptor occupancy of bemarituzumab were determined. Simulation was conducted to estimate dose and schedule to achieve an empirical target C_trough in a phase 2 trial (FIGHT, NCT03694522) for patients receiving first-line treatment combined with modified 5-fluourouracil, oxaliplatin and leucovorin (mFOLFOX6) for gastric and gastroesophageal junction adenocarcinoma.

Results

Bemarituzumab PK is best described by a two-compartment model with parallel linear and nonlinear (Michaelis–Menten) elimination from the central compartment. Albumin, gender, and body weight were identified as the covariates on the linear clearance and/or volume of distribution in the central compartment, and no dose adjustment was warranted. An empirical target of bemarituzumab C_trough of ≥ 60 µg/mL was projected to achieve > 95% receptor occupancy based on in vitro data. Fifteen mg/kg every 2 weeks, with a single dose of 7.5 mg/kg on Cycle 1 Day 8, was projected to achieve the target C_trough on Day 15 in 98% of patients with 96% maintaining the target at steady state, which was confirmed in the FIGHT trial.

Conclusion

A projected dose and schedule to achieve the target C_trough was validated in phase 1 of the FIGHT trial which supported selection of the phase 2 dose and schedule for bemarituzumab.

Electronic supplementary material

The online version of this article (10.1007/s00280-020-04139-4) contains supplementary material, which is available to authorized users.

Bevacizumab as a potential anti-angiogenic therapy in schistosomiasis: A double-edged, but adjustable weapon

AIM

Investigating the anti-angiogenic effect of bevacizumab on chronic schistosomiasis mansoni in a trial to hinder the Schistosome-induced angiogenesis and porto-systemic shunting complications.

METHODS

The immunohistochemical expression of CD34, VEGF-R1, PCNA and α-SMA (angiogenesis markers) was analysed in the lung, liver and gastrointestinal junctions of chronic S mansoni infected mice after intraperitoneal injection of bevacizumab. The effect of prolonged administration of bevacizumab with praziquantel was also assessed through parasitic load, protective index, granuloma and fibrous tissue evaluation.

RESULTS

A regression in the vascular activity and microvascular density was observed in the infected mice after receiving bevacizumab. They had a significantly less VEGF-R1, PCNA, CD-34 and α-SMA expression in comparison to the infected untreated mice. The least tissue egg count was reported in mice received bevacizumab for 6 weeks (Mean = 27 120). However, they had persistent liver granulomas, and massively amalgamated fibrosis. Interestingly, the least faecal egg and tissue worms counts (Mean = 112, 13.4), and the highest protection index (39.26) were reported in mice received bevacizumab for 3 weeks, with marked granuloma, and fibrous tissue resolution.

CONCLUSIONS

Bevacizumab has a promising protective effect against the Schistosoma-induced angiogenesis. As an adjuvant to praziquantel, it is important to adjust the appropriate duration of administration that achieves the best schistosomicidal effect without impeding granuloma and fibrous tissue resolution.

Anti-Idiotype DNA Aptamer Affinity Purification⁻High-Temperature Reversed-Phase Liquid Chromatography: A Simple, Accurate, and Selective Bioanalysis of Bevacizumab

This study presents a simple, accurate, and selective bioanalytical method of bevacizumab detection from plasma samples based on aptamer affinity purification–high-temperature reversed-phased liquid chromatography (HT-RPLC) with fluorescence detection. Bevacizumab in plasma samples was purified using magnetic beads immobilized with an anti-idiotype DNA aptamer for bevacizumab. The purified bevacizumab was separated with HT-RPLC and detected with its native fluorescence. Using aptamer affinity beads, bevacizumab was selectively purified and detected as a single peak in the chromatogram. HT-RPLC achieved good separation for bevacizumab with a sharp peak within 10 min. The calibration curves of the two monoclonal antibodies ranged from 1 to 50 μg/mL and showed good correlation coefficients (r² > 0.999). The limit of detection (LOD) and lower limit of quantification (LLOQ) values for bevacizumab were 0.15 and 0.51 μg/mL, respectively. The proposed method was successfully applied to the bioanalysis of the plasma samples obtained from the patients with lung cancer and may be extended to plan optimal therapeutic programs and for the evaluation of biological equivalencies in the development of biosimilars.

Long-Term Effects of Bevacizumab on Vestibular Schwannoma Volume in Neurofibromatosis Type 2 Patients

Introduction  Bevacizumab offers a medical treatment that may slow the growth of vestibular schwannomas (VS) and possibly preserve hearing in patients with neurofibromatosis type 2 (NF2). This study aims to investigate the effect of long-term bevacizumab treatment on VS progression. Methods  Demographic, clinical, audiometric, and radiographic data were collected from the medical records of NF2 patients treated with bevacizumab at a tertiary medical center. Results  Eleven tumors from seven NF2 patients treated with bevacizumab were analyzed. The median age was 17 years (range: 12-47 years). Median bevacizumab treatment time was 33 months (range: 12-74 months). Of five patients with serviceable hearing pretreatment, one (20%) maintained serviceable hearing during bevacizumab therapy. Significantly slower growth rates for both tumor diameters and tumor volumes were identified during active bevacizumab treatment. Median tumor diameters and volumes during active bevacizumab treatment were 0 cm/year (range: -0.13-0.17 cm/year) and 0.1 cm ³ /year (range: -0.92-0.41), compared with 0.37 cm/year (range: 0-1.5 cm/year, p  = 0.0011) and 1.38 cm ³ /year (range: 0.013-3.74), respectively, without bevacizumab treatment ( p  = 0.0263). Reduced tumor progression was noted with bevacizumab treatment utilizing both linear greatest diameter (hazard ratio 0.16, p  = 0.006) and segmentation volumes (hazard ratio 0.15, p  = 0.023). Complications of bevacizumab treatment included fatigue (43%), nausea/vomiting (43%), hypertension (43%), epistaxis (29%), and proteinuria (29%). One subject had a cerebrovascular accident detected on screening magnetic resonance imaging without symptoms or neurological sequelae. Discussion  Bevacizumab may reduce tumor growth rate and the risk of progression based on both volumetric and linear measurements.

An overview of cancer immunotherapeutic strategies

Artificially boosting body's immune response is one of the most exciting, effective and promising advancements in the treatment of cancers. Cancer immunotherapeutics consist of variety of treatment approaches such as cytokine therapy, adoptive T-cell transfer therapy, and antibodies that stimulate innate and adoptive immune responses. In addition to this, development of HPV vaccine has paved way toward the development of other cancer vaccines. Checkpoint blockade inhibitors, for example, anti-programmed cell death protein 1 and anti-cytotoxic T-lymphocyte-associated antigen-4, chimeric antigen receptor T-cell therapy and monoclonal antibodies are emerging as other major breakthroughs that are highly effective against cancer. This review addresses the current status of immunotherapeutic strategies against cancer and provides baseline data for future research.

Antiangiogenic therapy: Markers of response, "normalization" and resistance

Currently in cancer treatment, one premise is to use antiangiogenic therapies in association with chemotherapy or radiotherapy to augment their efficacy by benefiting from the vascular "normalization" induced by antiangiogenic therapy. This concept defines the time during which the tumor blood vessels adopt normal-like morphology and functionality, i.e. the blood vessels become more mature, the perfusion augments and hypoxia decreases. To date, there is such a diversity of treatment protocols where the type of antiangiogenic to adopt, its dose and duration of administration are different, that knowing when and how to treat is problematic. In this review, we analyzed thoroughly preclinical and clinical studies that use antiangiogenic treatments to benefit from the "normalization" and showed that the effects depend on the type of antiangiogenic administrated (anti-VEGF, anti-VEGFR, Multi-Kinase Inhibitor) and on the duration of treatment. Finally, biomarkers of "normalization" and resistance that could be used in the clinic are presented.

PET/CT in the Evaluation of Response to Treatment of Liver Metastases from Colorectal Cancer with Bevacizumab and Irinotecan

The present approach at our institution for the treatment of patients with colorectal (CRC) cancer and with liver metastases planned for metastasectomy is the neoadjuvant administration of Bevacizumab with Irinotecan based therapy. Metabolic imaging of tumor viability with 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET), and simultaneous anatomic localization provided by low-dose non-enhanced computed tomography (CT), can be obtained in a combined modality FDG-PET/CT scan. The purpose of this study was to evaluate the possible contribution of FDG-PET/CT as a surrogate marker to evaluate treatment response of liver metastases in vivo. This is a retrospective evaluation of 18F-FDG PET and CT findings in the first seven consecutive patients. FDG-PET/CT scans were performed before the start of the neoadjuvant and after four cycles of therapy, just prior to surgery. Results were compared to concurrent contrast-enhanced CT, when required, and pathology. Response to treatment was determined according to RECIST size criteria obtained from data from thin (3–5mm) slice CT, and changes in uptake of 18F-FDG uptake on PET.

A total of 20 liver lesions were evaluated in seven patients. Overall, 6/7 patients had favorable response to treatment, and only one had progression of disease. One patient was found to be inoperable at surgery. Biopsy was obtained in 1/4 lesions in this patient, while pathology was unable for the remaining three lesions. As such, pathologic validation of findings was available for 17/20 lesions. Complete response (CR) was evident on FDG-PET in 10/17 (58%) lesions, whereas only 4/17(23%) were deemed CR by CT. Similarly, only 1/17 (6%) lesion appeared stable by FDG-PET criteria, whereas three (18%) were termed stable disease (SD) according to size on CT.

FDG-PET findings correlated better than CT with pathology, and were more indicative of pathology. Overall PET/CT correctly predicted necrosis at pathology in 70% vs. 35% by CT. Our results suggest that 18F-FDG PET may be instrumental for predicting the pathologic response to Bevacizumab based therapy.

Ultrasound-enhanced bevacizumab release from echogenic liposomes for inhibition of atheroma progression

CONTEXT

Bevacizumab (BEV) is a monoclonal antibody to vascular endothelial growth factor (VEGF) that ameliorates atheroma progression by inhibiting neovascularization.

OBJECTIVE

We aimed to determine whether BEV release from echogenic liposomes (BEV-ELIP) could be enhanced by color Doppler ultrasound (US) and whether the released BEV inhibits VEGF expression by endothelial cells in vitro.

MATERIALS AND METHODS

BEV-ELIP samples were subjected to 6 MHz color Doppler ultrasound (MI = 0.4) for 5 min. We assessed release of BEV with a direct ELISA and with fluoresceinated BEV (FITC-BEV) loaded into ELIP by the same method. Human umbilical vein endothelial cell (HUVEC) cultures were stimulated to express VEGF by 10 nM phorbol-12-myristate 13-acetate (PMA). Cell-associated VEGF levels were determined using a cell-based ELISA.

RESULTS

Overall, US caused an additional 100 µg of BEV to be released or exposed per BEV-ELIP aliquot within 60 min BEV-ELIP treated with US inhibited VEGF expression by 90% relative to non-treated controls and by 70% relative to BEV-ELIP without US. Also, US-treated BEV-ELIP inhibited HUVEC proliferation by 64% relative to untreated controls and by 45% relative to BEV-ELIP without US.

DISCUSSION AND CONCLUSION

We have demonstrated that BEV-ELIP retains its VEGF-binding activity in a liposomal formulation and that clinical Doppler US can significantly increase that activity, both by releasing free BEV and by enhancing the surface exposure of the immunoreactive antibody.

The role of death receptor 3 in the biological behavior of hepatocellular carcinoma cells

Death receptor 3 (DR3) belongs to the tumor necrosis factor (TNF) receptor superfamily, primarily found in lymphoid tissues. Reports have determined that DR3 may also be distributed in numerous types of tumors. Therefore, it is thought that DR3 may have an important role in the process of tumorigenesis. The aim of the present study was to observe the effect of silencing DR3 expression on hepatocarcinoma cell growth, apoptosis and invasion in order to elucidate the role of DR3 in tumor development. The hepatocarcinoma cell lines (HepG2, Huh7, SMMC7721 and Bel-7402) and normal human liver cells (HL-7702) were transfected with three stealth RNA interference (RNAi) sequences that target the DR3 gene. Reverse transcription quantitative polymerase chain reaction was used to detect the expression levels of DR3 in hepatocarcinoma cell lines and normal liver HL-7702 cells. MTT assay and flow cytometry (FCM) were used to determine the rates of cell proliferation and apoptosis, respectively. Following silencing of the DR3 gene, western blot analysis was used to determine the protein expression of P53, Fas, Caspase8, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and Caspase3. DR3 messenger RNA (mRNA) expression in hepatocarcinoma cell lines was significantly increased compared with that in the normal liver cell line. Three targeted DR3 gene small interfering RNAs significantly inhibited DR3 gene expression in Bel-7402 cells at the nucleic acid level. AF02670.1_stealth_883 and cocktail demonstrated the most efficient inhibition of DR3 gene expression at 48 and 72 h following transfection, with mRNA inhibition rates of 89.46 and 92.75%, and 90.53 and 94.25% (P<0.01), respectively. Cell viability was significantly reduced by AF02670.1_stealth_883 and RNAi cocktail at 24, 48 and 72 h following transfection. The inhibition rates of cell proliferation were 50.76 and 61.76% (P<0.05) at 72 h following transfection. FCM revealed that AF02670.1_stealth_883 and RNAi cocktail also induced apoptosis in Bel-7402 cells at 72 h following transfection. Reduction of NF-κB and P53 levels was observed (P<0.05) in Bel-7402 cells following DR3 silencing, whereas levels of Fas, Caspase3 and Caspase8 were markedly elevated (P<0.05). DR3 expression levels in hepatocellular carcinoma cells were significantly higher than those in normal cells. DR3 silencing effectively inhibited proliferation and invasion of hepatocellular carcinoma cells in vitro. However, silencing of the DR3 gene affect levels of apoptosis antigen-3 ligand in cells, therefore indicating that it may be involved with other pathways that regulate apoptosis in HCCs. In conclusion, the results of the present study indicated that DR3 may be a promising therapeutic target molecule for further study of hepatocellular carcinoma gene therapy.

Evaluation of a novel blood pressure scoring method and its association with clinical response in cancer patients treated with anti-vascular endothelial growth factor therapy

BACKGROUND

The purposes of this study were to establish a novel blood pressure (BP) scoring method and to correlate it with clinical response in advanced cancer patients treated with anti-vascular endothelial growth factor (VEGF) therapies.

METHODS

We retrospectively analyzed data for 368 patients from 23 clinical trials that included at least one anti-VEGF agent. We determined BP scores using the traditional Common Terminology Criteria for Adverse Events (CTCAE) version 4.0 and our novel method that considers both BP readings and number of anti-hypertensive medications the patient received. BP scores were categorized at baseline and four months. Logistic regression analysis correlated elevated scores with clinical response. Agreement between the CTCAE and the new method was assessed.

RESULTS

Under the new BP scoring method, partial response rates were 20 % in patients with an elevated score at four months versus 6 % in patients without elevated score (P < 0.001). When adjusted for tumor type, age, sex, history of anti-VEGF treatment, and number of anti-VEGF treatments, elevated BP under the new scoring method had an odds ratio of 3.8 (95 % confidence interval [CI]: 1.8, 8.2; P < 0.001). The kappa statistic for agreement between the CTCAE and new scoring methods was 0.57 (95 % CI: 0.47, 0.67; P < 0.001), indicating significant concordance.

CONCLUSION

Using the novel scoring method, an increase in BP scores was a marker for favorable clinical response in patients who received anti-VEGF treatment. This new method ultimately provides information with regard to clinical tumor response over and above that provided by the CTCAE scoring method.

Determining the optimal dose in the development of anticancer agents

Identification of the optimal dose remains a key challenge in drug development. For cytotoxic drugs, the standard approach is based on identifying the maximum tolerated dose (MTD) in phase I trials and incorporating this to subsequent trials. However, this strategy does not take into account important aspects of clinical pharmacology. For targeted agents, the dose-effect relationships from preclinical studies are less obvious, and it is important to change the way these agents are developed to avoid recommending drug doses for different populations without evidence of differential antitumour effects in different diseases. The use of expanded cohorts in phase I trials to better define MTD and refine dose optimization should be further explored together with a focus on efficacy rather than toxicity-based predictions. Another key consideration in dose optimization is related to interindividual pharmacokinetic variability. High variability in intra-individual pharmacokinetics has been observed for many orally-administered drugs, especially those with low bioavailability, which might complicate identification of dose-effect relationships. End-organ dysfunction, interactions with other prescription drugs, herbal supplements, adherence, and food intake can influence pharmacokinetics. It is important these variables are identified during early clinical trials and considered in the development of further phase II and subsequent large-scale phase III studies.

Dynamic-susceptibility contrast agent MRI measures of relative cerebral blood volume predict response to bevacizumab in recurrent high-grade glioma

BACKGROUND

The anti-VEGF antibody, bevacizumab, is standard treatment for patients with recurrent glioblastoma. In this setting, traditional anatomic MRI methods such as post-contrast T1-weighted and T2-weighted imaging are proving unreliable for monitoring response. Here we evaluate the prognostic significance of pre- and posttreatment relative cerebral blood volume (rCBV) derived from dynamic susceptibility contrast MRI to predict response to bevacizumab.

METHODS

Thirty-six participants with recurrent high-grade gliomas who underwent rCBV imaging 60 days before and 20-60 days after starting bevacizumab treatment were enrolled. Tumor regions of interest (ROIs) were determined from deltaT1 maps computed from the difference between standardized post and precontrast T1-weighted images. Both pre- and posttreatment rCBV maps were corrected for leakage and standardized (stdRCBV) to a consistent intensity scale. The Kaplan-Meier method was used to determine if either the pre- or post-bevacizumab stdRCBV within the tumor ROI was predictive of overall survival (OS) or progression free survival (PFS).

RESULTS

The OS was significantly longer if either the pre- (380d vs 175d; P=.0024) or posttreatment stdRCBV (340d vs 186d; P = .0065) was <4400. The posttreatment stdRCBV was also predictive of PFS (167d vs 78d; P = .0006). When the stdRCBV values were both above versus both below threshold, the OS was significantly worse (100.5d vs 395d; P < .0001). With a 32.5% decrease in stdRCBV, the risk of death was reduced by about 68% but increased by 140% with a 29% increase in stdRCBV.

CONCLUSIONS

Standardized rCBV is predictive of OS and PFS in patients with recurrent high-grade brain tumor treated with bevacizumab.

Irradiation-induced angiosarcoma and anti-angiogenic therapy: a therapeutic hope?

Angiosarcomas are rare soft-tissue sarcomas of endothelial cell origin. They can be sporadic or caused by therapeutic radiation, hence secondary breast angiosarcomas are an important subgroup of patients. Assessing the molecular biology of angiosarcomas and identify specific targets for treatment is challenging. There is currently great interest in the role of angiogenesis and of angiogenic factors associated with tumor pathogenesis and as targets for treatment of angiosarcomas. A primary cell line derived from a skin fragment of a irradiation-induced angiosarcoma patient was obtained and utilized to evaluate cell biomarkers CD31, CD34, HIF-1 alpha and VEGFRs expression by immunocytochemistry and immunofluorescence, drugs cytotoxicity by cell counting and VEGF release by ELISA immunoassay. In addition to previous biomarkers, FVIII and VEGF were also evaluated on tumor specimens by immunohistochemistry to further confirm the diagnosis. We targeted the VEGF-VEGFR-2 axis of tumor angiogenesis with two different class of vascular targeted drugs; caprelsa, the VEGFR-2/EGFR/RET inhibitor and bevacizumab the anti-VEGF monoclonal antibody. We found the same biomarkers expression either in tumor specimens and in the cell line derived from tumor. In vitro experiments demonstrated that angiogenesis plays a pivotal role in the progression of this tumor as cells displayed high level of VEGFR-2, HIF-1 alpha strongly accumulated into the nucleus and the pro-angiogenic factor VEGF was released by cells in culture medium. The evaluation of caprelsa and bevacizumab cytotoxicity demonstrated that both drugs were effective in inhibiting tumor proliferation. Due to these results, we started to treat the patient with pazopanib, which was the unique tyrosine kinase inhibitor available in Italy through a compassionate supply program, obtaining a long lasting partial response. Our data suggest that the study of the primary cell line could help physicians in choosing a therapeutic approach for patient that almost in vitro shows chances of success and that the anti-angiogenetic agents are a reliable therapeutic opportunity for angiosarcomas patients.

Human antibodies targeting the C-type lectin-like domain of the tumor endothelial cell marker clec14a regulate angiogenic properties in vitro

It has been suggested that clec14a may be involved in tumor angiogenesis. However, a molecular mechanism has not been clearly identified. In this study, we show for the first time that C-type lectin-like domain (CTLD) of clec14a may be important for regulating cell migration and filopodia formation. Using phage display technology, recombinant human antibodies specific to the CTLDs of human and mouse clec14a (clec14a-CTLD (immunoglobulin G) IgG) were selected. Functional assays using the antibodies showed that clec14a-CTLD IgGs specifically blocked endothelial cell migration and tube formation without affecting cell viability or activation. Further, clec14a-CTLD IgGs inhibited clec14a-mediated cell–cell contact by blocking interaction between CTLDs. Finally, clec14a cross-linking by the clec14a-CTLD IgGs significantly downregulated clec14a expression on the surface of endothelial cells. These results strongly suggest that the clec14a-CTLD may be a key domain in angiogenesis, and that clec14a-CTLD IgGs specifically inhibit angiogenesis by modulating CTLD-mediated cell interactions and clec14a expression on the surface of endothelial cells.

Vascular endothelial growth factor (VEGF) expression in locally advanced prostate cancer: secondary analysis of radiation therapy oncology group (RTOG) 8610

Background

Angiogenesis is a key element in solid-tumor growth, invasion, and metastasis. VEGF is among the most potent angiogenic factor thus far detected. The aim of the present study is to explore the potential of VEGF (also known as VEGF-A) as a prognostic and predictive biomarker among men with locally advanced prostate cancer.

Methods

The analysis was performed using patients enrolled on RTOG 8610, a phase III randomized control trial of radiation therapy alone (Arm 1) versus short-term neoadjuvant and concurrent androgen deprivation and radiation therapy (Arm 2) in men with locally advanced prostate carcinoma. Tissue samples were obtained from the RTOG tissue repository. Hematoxylin and eosin slides were reviewed, and paraffin blocks were immunohistochemically stained for VEGF expression and graded by Intensity score (0–3). Cox or Fine and Gray’s proportional hazards models were used.

Results

Sufficient pathologic material was available from 103 (23%) of the 456 analyzable patients enrolled in the RTOG 8610 study. There were no statistically significant differences in the pre-treatment characteristics between the patient groups with and without VEGF intensity data. Median follow-up for all surviving patients with VEGF intensity data is 12.2 years. Univariate and multivariate analyses demonstrated no statistically significant correlation between the intensity of VEGF expression and overall survival, distant metastasis, local progression, disease-free survival, or biochemical failure. VEGF expression was also not statistically significantly associated with any of the endpoints when analyzed by treatment arm.

Conclusions

This study revealed no statistically significant prognostic or predictive value of VEGF expression for locally advanced prostate cancer. This analysis is among one of the largest sample bases with long-term follow-up in a well-characterized patient population. There is an urgent need to establish multidisciplinary initiatives for coordinating further research in the area of human prostate cancer biomarkers.

Bevacizumab every 4 weeks is as effective as every 2 weeks in combination with biweekly FOLFIRI in metastatic colorectal cancer

PURPOSE

The efficacy and tolerability of bevacizumab every 2 or 4 weeks using the same dosage in combination with biweekly FOLFIRI were retrospectively evaluated in metastatic colorectal cancer (mCRC) patients in the first-line and second-line therapy.

PATIENTS AND METHODS

A total of 332 patients from six centers were evaluated. The patients had received biweekly FOLFIRI in combination with bevacizumab 5 mg/kg every 2 weeks or every 4 weeks schedule for various reasons in individual patients.

RESULTS

Approximately 70 % of all patients had 2-week treatment schedule. In the first-line therapy (n = 240), the overall response rate (ORR) was 34.1 % in 2-week and 36.3 % in 4-week groups. Median progression-free survival (PFS) was 8 months (95 %CI, 6.8-9.2) and 9 months (95 %CI, 6.6-11.4) (p = 0.074), and median overall survival (OS) was 22 months (95 %CI, 15.8-28.2) and 20 months (95 %CI, 8.1-31.9) (p = 0.612) in 2- and 4-week groups, respectively. One-year survival rate was 76.2 % for 2-week group and 73.2 % for 4-week group. In the second-line therapy (n = 92), the ORR was similar between the groups (24.5 vs 25.9 % in 2- and 4-week groups, respectively). Median PFS was 6 months (95 %CI, 4.7-7.3) and 11 months (95 %CI, 6.3-15.7) (p = 0.074), and median OS was 15 months (95 %CI, 9.6-20.4) and 17 months (95 %CI, 13.7-20.3) (p = 0.456) for 2-week and for 4-week groups, respectively. One-year survival rate was 61.3 % for 2-week and 71.3 % for 4-week groups. Toxicity profile was similar in 2- and 4-week groups and included neutropenia, febrile neutropenia, nausea and vomiting, diarrhea, mucositis, bleeding, hypertension, thromboembolism and fistulization.

CONCLUSION

Bevacizumab 5 mg/kg every 2 weeks or every 4 weeks in combination with biweekly FOLFIRI had similar efficacy and tolerability in mCRC. Because of the retrospective nature of our study, the data should be examined cautiously. However, our study clearly points out the need for determination of optimum biological dosing interval of bevacizumab in well-designed, prospective, randomized trials.

Beyond antiangiogenesis: vascular modulation as an anticancer therapy-a review

This review attempts to move beyond the traditional borders of antiangiogenesis and toward the dynamic, evolving strategies of vascular modulation. This repositioning entails a two-fold paradigm shift: conceptually, to a view of antiangiogenesis as only one part of a larger story, and therapeutically, to approaches which attempt to modulate tumor blood flow instead of simply inhibiting it. Three vascular modulation strategies-provascular, antivascular, and redistributive-are presented with representative compounds. These vascular modulation strategies are described in specific measurable characteristics (blood vessel maturity and type, effect on blood flow, microenvironmental target, molecular target, angiogenic biomarker, and imaging biomarkers) that will help define the tumor types that are more susceptible to a particular vascular modulation strategy thereby guiding therapeutic agent selection and enabling a personalized medicine approach.

Anti-VEGF therapy with bevacizumab for anterior segment eye disease

PURPOSE

To review the current literature concerning the use of bevacizumab in treating neovascular disorders affecting the anterior segment ocular structures.

METHODS

The authors reviewed the literature on anti-vascular endothelial growth factor (VEGF) therapy with bevacizumab for various anterior segment neovascular disorders that was indexed in MEDLINE (up to January 2011).

RESULTS

Response to bevacizumab anti-VEGF therapy is variable, based on the amount of scarring, the chronicity and extent of corneal neovascularization, the disease process, and the medication formulation and its route of administration. Anti-VEGF agents are especially effective when administered early, before anatomical changes, such as corneal neovascularization and/or angle closure, are established. Neovascularization can recur if the ischemic or inflammatory process is not reversed, so eyes with long-standing diseases, such as autoimmune disorders that involve ongoing inflammation and VEGF production, seem to be less responsive to bevacizumab anti-VEGF therapy. For established neovascularization, combining anti-VEGF agents with the removal of established vessels may be more effective than anti-VEGF therapy alone. Subconjunctival bevacizumab may be more appropriate for focal, deep, and peripheral neovascularization, whereas diffuse superficial neovascularization with central corneal involvement may be best treated via topical application.

CONCLUSIONS

Besides the widely accepted use of bevacizumab in cancer therapy and chorioretinal neovascularization, the initial, striking, short-term response and patients' high tolerance of local bevacizumab therapy offer encouraging results for the potential role of anti-VEGF agents in treating anterior segment neovascular disorders. Controlled prospective trials are needed to establish the long-term safety, efficacy, and dosing guidelines for the use of anti-VEGF agents in anterior segment neovascularization.

Exposure-response relationship of AMG 386 in combination with weekly paclitaxel in recurrent ovarian cancer and its implication for dose selection

Purpose

To characterize exposure–response relationships of AMG 386 in a phase 2 study in advanced ovarian cancer for the facilitation of dose selection in future studies.

Methods

A population pharmacokinetic model of AMG 386 (N = 141) was developed and applied in an exposure–response analysis using data from patients (N = 160) with recurrent ovarian cancer who received paclitaxel plus AMG 386 (3 or 10 mg/kg once weekly) or placebo. Reduction in the risk of progression or death with increasing exposure (steady-state area under the concentration-versus-time curve [AUC_ss]) was assessed using Cox regression analyses. Confounding factors were tested in multivariate analysis. Alternative AMG 386 doses were explored with Monte Carlo simulations using population pharmacokinetic and parametric survival models.

Results

There was a trend toward increased PFS with increased AUC_ss (hazard ratio [HR] for each one-unit increment in AUC_ss, 0.97; P = 0.097), suggesting that the maximum effect on prolonging PFS was not achieved at the highest dose tested (10 mg/kg). Among patients with AUC_ss ≥ 9.6 mg h/mL, PFS was 8.1 months versus 5.7 months for AUC_ss < 9.6 mg h/mL and 4.6 months for placebo. No relationship between AUC_ss and grade ≥3 adverse events was observed. Simulations predicted that AMG 386 15 mg/kg once weekly would result in an AUC_ss ≥ 9.6 mg h/mL in >90% of patients with median PFS of 8.2 months versus 5.0 months for placebo (HR [15 mg/kg vs. placebo], 0.56).

Conclusions

Increased exposure to AMG 386 was associated with improved clinical outcomes in recurrent ovarian cancer, supporting the evaluation of a higher dose in future studies.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-011-1787-5) contains supplementary material, which is available to authorized users.

Personalized cancer medicine--advances and socio-economic challenges

It was Hippocrates, the father of Western medicine, who first emphasized the patient as the most important determinant of therapeutic efficacy. Although the principle of adjusting treatment to specific patient characteristics has since been the strategy of physicians, this is undermined by a population-biased approach to drug development. Therefore, it is generally true to say that our current evidential approach to cancer treatment is driven more by drug-regulation requirements and market considerations than the specific needs of an individual patient. But, with cancer drug costs now spiraling out of control and the modest efficacy typically seen in patients, the community is again turning to Hippocrates' ancient paradigm--this time with emphasis on molecular considerations. Rapidly evolving technologies are empowering us to describe the molecular 'nature' of a patient and/or tumor and with this has come the beginning of truly personalized medicine, with maximized efficacy, cost effectiveness and hopefully improved survival for the patient.

Anti-angiogenic therapy in glioma

There has been great interest in developing anti-angiogenic therapies for the treatment of patients with high-grade gliomas. In fact, some anti-angiogenic agents are now routinely used for the treatment of patients with glioblastoma. However, the use of these agents is largely based on trials which indicate an initial radiographic response, while it remains unclear whether any anti-angiogenic therapies tested to date have improved the overall survival of patients with malignant glial tumours. This manuscript reviews the landscape of anti-angiogenic therapy in glioma, with a focus on GBM, and demonstrates that further innovation is needed to determine the true utility of anti-angiogenic therapy.

Characterization of bevacizumab dose response relationship in U87 brain tumors using magnetic resonance imaging measures of enhancing tumor volume and relative cerebral blood volume

Despite the early promising results with the anti-angiogenic agent, bevacizumab, to prolong time to progression in patients with brain tumors, the optimal dose and drug combinations have not yet been defined. The purpose of this study was to characterize the bevacizumab dose-response relationship for brain tumors by measuring the contrast-agent enhanced tumor volumes and relative cerebral blood volume (rCBV) using dynamic susceptibility contrast (DSC) imaging. The studies, performed in the U87 brain tumor model using doses of bevacizumab ranging from 0 to 10 mg/kg, demonstrate that tumor growth and vascularity are inhibited at all doses used, compared to untreated controls. However, only the maximum dose showed a statistically significant difference in growth rate. Conversely tumor vascularity, as measured with rCBV, was inhibited equally well for all doses used with no clear indication that higher doses are more effective.

Antibody targeting of cathepsin S inhibits angiogenesis and synergistically enhances anti-VEGF

BACKGROUND

Angiogenesis is a key hallmark of tumourigenesis and its inhibition is a proven strategy for the development of novel anti-cancer therapeutics. An important aspect of early angiogenesis is the co-ordinated migration and invasion of endothelial cells through the hypoxic tumour tissue. Cathepsin S has been shown to play an important role in angiogenesis as has vascular endothelial growth factor (VEGF). We sought to assess the anti-angiogenic effect of Fsn0503, a novel cathepsin S inhibitory antibody, when combined with anti-VEGF on vascular development.

METHODOLOGY/PRINCIPAL FINDINGS

Cathepsin S expression and secretion from endothelial cells was characterised using RT-PCR and western blotting. We further show that cathepsin S promotes pericellular hydrolysis of extracellular matrix components in the tumour microenvironment and facilitates endothelial invasion. The cathepsin S inhibitory antibody, Fsn0503, blocks extracellular proteolysis, inhibiting endothelial invasion and tube formation in cell-based assays. The anti-angiogenic effects of Fsn0503 were also shown in vivo where it significantly retarded the development of vasculature in human xenograft models. Furthermore, when Fsn0503 was combined with an anti-VEGF antibody, a synergistic inhibition of microvascular development was observed.

CONCLUSIONS/SIGNIFICANCE

Taken together, this data demonstrates that the antibody-mediated targeting of cathepsin S represents a novel method of inhibiting angiogenesis. Furthermore, when used in combination with anti-VEGF therapies, Fsn0503 has the potential to significantly enhance current treatments of tumour neovascularisation and may also be of use in the treatment of other conditions associated with inappropriate angiogenesis.

Cediranib in combination with various anticancer regimens: results of a phase I multi-cohort study

BACKGROUND

Cediranib is a highly potent vascular endothelial growth factor (VEGF) signaling inhibitor of all three VEGF receptors. This phase I, single-center, dose-finding study was designed primarily to investigate the safety and pharmacokinetics (PK) of cediranib with various anticancer regimens in patients with advanced solid tumors.

EXPERIMENTAL DESIGN

Oral cediranib 20, 30, and/or 45 mg/day was given in combination with standard mFOLFOX6; docetaxel; irinotecan; irinotecan and cetuximab; or pemetrexed. The novel study design allowed simultaneous evaluation of the safety and PK of these regimens with cediranib in one study. Secondary assessments included a preliminary evaluation of efficacy.

RESULTS

Fifty-nine patients received cediranib and were evaluable for safety. The most common adverse events across the study were fatigue and diarrhea (both n = 52). The most common CTC grade ≥ 3 adverse events were neutropenia (n = 19) and fatigue (n = 16). Cediranib did not appear to have a major effect on the PK profile of any chemotherapy agent tested. A preliminary assessment of efficacy showed that objective responses were achieved in some patients (n = 6) who had previously progressed on similar regimens without cediranib.

CONCLUSION

In this group of heavily pretreated patients, the study design permitted simultaneous assessment of multiple treatment arms. Treatment with cediranib and the various anticancer regimens was generally well tolerated, with no apparent PK interaction and preliminary evidence of antitumor activity.

Determination of breast cancer response to bevacizumab therapy using contrast-enhanced ultrasound and artificial neural networks

OBJECTIVE

The purpose of this study was to evaluate contrast-enhanced ultrasound and neural network data classification for determining the breast cancer response to bevacizumab therapy in a murine model.

METHODS

An ultrasound scanner operating in the harmonic mode was used to measure ultrasound contrast agent (UCA) time-intensity curves in vivo. Twenty-five nude athymic mice with orthotopic breast cancers received a 30-microL tail vein bolus of a perflutren microsphere UCA, and baseline tumor imaging was performed using microbubble destruction-replenishment techniques. Subsequently, 15 animals received a 0.2-mg injection of bevacizumab, whereas 10 control animals received an equivalent dose of saline. Animals were reimaged on days 1, 2, 3, and 6 before euthanasia. Histologic assessment of excised tumor sections was performed. Time-intensity curve analysis for a given region of interest was conducted using customized software. Tumor perfusion metrics on days 1, 2, 3, and 6 were modeled using neural network data classification schemes (60% learning and 40% testing) to predict the breast cancer response to therapy.

RESULTS

The breast cancer response to a single dose of bevacizumab in a murine model was immediate and transient. Permutations of input to the neural network data classification scheme revealed that tumor perfusion data within 3 days of bevacizumab dosing was sufficient to minimize the prediction error to 10%, whereas measurements of physical tumor size alone did not appear adequate to assess the therapeutic response.

CONCLUSIONS

Contrast-enhanced ultrasound may be a useful tool for determining the response to bevacizumab therapy and monitoring the subsequent restoration of blood flow to breast cancer.

Effective strategies for management of hypertension after vascular endothelial growth factor signaling inhibition therapy: results from a phase II randomized, factorial, double-blind study of Cediranib in patients with advanced solid tumors

PURPOSE Hypertension is a commonly reported adverse effect after administration of vascular endothelial growth factor (VEGF) inhibitors. Cediranib is a highly potent and selective VEGF signaling inhibitor of all three VEGFRs. This study prospectively investigated hypertension management to help minimize dose interruptions/reductions to maximize cediranib dose intensity. PATIENTS AND METHODS Patients (n = 126) with advanced solid tumors were randomly assigned to one of four groups: cediranib 30 or 45 mg/d with or without antihypertensive prophylaxis. All patients developing hypertension on cediranib treatment were treated with a standardized, predefined hypertension management protocol. Results Cediranib was generally well tolerated, and all groups achieved high-dose intensities in the first 12 weeks (> 74% in all groups). Antihypertensive prophylaxis did not result in fewer dose reductions or interruptions. Increases in blood pressure, including moderate and severe readings of hypertension, were seen early in treatment in all groups and successfully managed. Severe hypertension occurred in one patient receiving prophylaxis versus 18 in the nonprophylaxis groups. Overall, there were nine partial responses, and 38 patients experienced stable disease >/= 8 weeks. CONCLUSION To our knowledge, this is the first prospective investigation of hypertension management during administration of a VEGF signaling inhibitor. All four regimens were well tolerated with high-dose intensities and no strategy was clearly superior. The current cediranib hypertension management protocol appears to be effective in managing hypertension compared with previous cediranib studies where no plan was in place, and early recognition and treatment of hypertension is likely to reduce the number of severe hypertension events. This protocol is included in all ongoing cediranib clinical studies.

Oncogenic and angiogenic growth factors accumulate during routine storage of apheresis platelet concentrates

PURPOSE

Platelet concentrates are important for support of patients with malignancies requiring myelotoxic chemotherapy. During storage, 10% to 15% of platelets may become activated resulting in the release of alpha-granules, which contain growth factors. We hypothesize that, during storage, growth factors accumulate in the plasma, specifically platelet-derived growth factor, vascular endothelial growth factor (VEGF), transforming growth factor-beta, and fibroblast growth factor-2, which may adversely affect cancer patients.

EXPERIMENTAL DESIGN

The concentrations of growth factors were measured by ELISA from the plasma of apheresis platelets serially throughout storage (days 1, 3, 5, and 7) and compared with concentrations in fresh plasma from healthy blood donors. Washing was evaluated as a method of growth factor removal, and an in vitro model of platelet transfusion in a patient receiving Bevacizumab (Avastin) using immunoprecipitation was employed to determine if Bevacizumab would be bound by the VEGF in apheresis platelets.

RESULTS

VEGF, platelet-derived growth factor, and transforming growth factor-beta were increased on day 1 versus fresh plasma and throughout storage reaching a relative maximum at outdate (P < 0.01, day 5 or 7). Fibroblast growth factor-2 concentrations were significantly increased on day 7 alone versus day 1 or to fresh plasma (P < 0.01). Washing removed 41 +/- 11% to 56 +/- 2% of the growth factors. Bevacizumab effectively bound the VEGF from apheresis platelets, with significant amounts of VEGF remaining in the supernatant.

CONCLUSIONS

Significant amounts of growth factors are present in apheresis platelets due to the isolation procedures, and these concentrations increase over storage, which may be partially removed by washing. In addition, apheresis platelet transfusion could affect cancer treatment by binding monoclonal antibodies directed against growth factors of tumor origin.

Lessons learned in the development of targeted therapy for malignant gliomas

The prognosis of patients with glioblastoma, anaplastic astrocytoma, and anaplastic oligodendroglioma remains poor despite standard treatment with radiotherapy and temozolomide. Molecular targeted therapy holds the promise of providing new, more effective treatment options with minimal toxicity. However, the development of targeted therapy for gliomas has been particularly challenging. The oncogenetic process in such tumors is driven by several signaling pathways that are differentially activated or silenced with both parallel and converging complex interactions. Therefore, it has been difficult to identify prevalent targets that act as key promoters of oncogenesis and that can be successfully addressed by novel agents. Several drugs have been tested, including epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (gefitinib and erlotinib), mammalian target of rapamycin (mTOR) inhibitors (temsirolimus and everolimus), and vascular endothelial growth factor receptor (VEGFR), protein kinase C-beta, and other angiogenesis pathways inhibitors (vatalanib, bevacizumab, and enzastaurin). Although preliminary efficacy results of most trials in recurrent disease have fallen short on expectations, substantial advances have been achieved by associated translational research. In this article, we seek to recapitulate the lessons learned in the development of targeted therapy for gliomas, including challenges and pitfalls in the interpretation of preclinical data, specific issues in glioma trial design, insights provided by translational research, changes in paradigms, and future perspectives.

Mechanisms of disease: angiogenesis and the management of breast cancer

Demonstration of the clinically significant activity of bevacizumab in breast cancer has attracted a great deal of interest. Numerous other antiangiogenic treatments are in clinical development and some established therapies including tamoxifen and trastuzumab might function, in part, by suppressing angiogenesis. In this Review, we discuss the potential of various components of the angiogenic pathway as prognostic and predictive factors in breast cancer. In addition, we describe existing clinical trials of antiangiogenic agents and the challenges facing the clinical development and optimum use of these agents for the treatment of breast cancer.

Nursing Considerations of Bevacizumab Use in Multiple Tumor Types

PURPOSE/OBJECTIVES

To update information concerning the antiangiogenic agent bevacizumab, discuss side effects, and provide information on nursing management of the side effects.

DATA SOURCES

Published articles, abstracts, and research data.

DATA SYNTHESIS

In clinical trials, the addition of bevacizumab to standard chemotherapy increased survival in patients with metastatic colorectal cancer and advanced non-small cell lung cancer and increased progression-free survival in patients with metastatic breast cancer. Bevacizumab also is being evaluated in combination with other targeted agents in various tumor types. Commonly reported side effects associated with bevacizumab include hypertension, proteinuria, and minor bleeding.

CONCLUSIONS

The value of bevacizumab in treating metastatic colorectal cancer has long been established. Clinical trial data have demonstrated the benefit of using bevacizumab in combination with standard chemotherapy in the treatment of non-small cell lung cancer and metastatic breast cancer. Because of bevacizumab's expanding role in cancer treatment, nurses need to know how to use it, be aware of possible side effects, and anticipate interventions.

IMPLICATIONS FOR NURSING

Nurses play an important role in the identification and management of adverse events associated with bevacizumab.

Bevacizumab in the management of solid tumors

Angiogenesis is defined as the formation of new blood vessels from a pre-existing vascular bed. By supplying nutrients and oxygen and removing waste products in malignant tumors, it is an essential process that regulates cancer growth and dissemination. This process is regulated by both pro- and antiangiogenic compounds. Vascular endothelial growth factor is one of the most important and best-studied proangiogenic factors. Bevacizumab, a monoclonal antibody against vascular endothelial growth factor, has been shown to inhibit angiogenesis and is proving to be of clinical benefit in a variety of tumor types. The strongest evidence comes from studies in advanced colorectal and non-small-cell lung cancer, with growing evidence in breast and epithelial ovarian tumors. The duration and timing of bevacizumab's use is currently the focus of several ongoing clinical trials.

Challenges for patient selection with VEGF inhibitors

As targeted therapies for cancer become increasingly integrated into standard practice, appropriate selection of the patients most likely to benefit from these therapies is now receiving critical scrutiny. Early experience with therapies directed at targets that are definitively overactive (e.g. the bcr-abl tyrosine kinase targeted by imatinib) or over-expressed [e.g. the human epidermal growth factor receptor 2 (HER2) targeted by trastuzumab] has generated the perception that pre-treatment target assessment is a pre-requisite for therapy with all targeted agents. However, emerging evidence suggests that this is not presently feasible for anti-angiogenic agents. Despite considerable evidence for the association of intratumoral and/or plasma vascular endothelial growth factor (VEGF) levels with tumor progression and/or poor prognosis, pre-treatment VEGF levels do not appear to be predictive of response to anti-angiogenic therapy. This may possibly be due to the complexity of the angiogenic pathways and the limitations associated with current methods of VEGF detection and quantification; e.g. low assay sensitivity and lack of standardized methods could prevent detection of very small increases in VEGF, which may be clinically important in patients with tumors that are highly dependent on this growth factor. In addition to a general lack of agreement as to the relative clinical relevance of circulating versus tumor VEGF levels, the absence of a 'gold standard' VEGF detection assay and the lack of a predefined, clinically relevant cut-off pose a significant hindrance to the clinical utility of VEGF measurements for therapy selection. Given the fundamental importance of angiogenesis for tumor growth and progression, and the key role of VEGF in these processes, presently it seems appropriate to view anti-VEGF agents such as bevacizumab (Avastin) as having potential utility, independently of pre-treatment screening. Further research is needed to define the relationship between potential surrogate markers of VEGF pathway activity and clinical outcomes.

Imaging tumor angiogenesis

Since the discovery of vascular-specific growth factors with angiogenic activity, there has been a significant effort to develop cancer drugs that restrict tumorigenesis by targeting the blood supply. In this issue of the JCI, Mancuso et al. use mouse models to better understand the plasticity of the tumor vasculature in the face of antiangiogenic therapy (see the related article beginning on page 2610). They describe a rapid regrowth of the tumor vasculature following withdrawal of VEGFR inhibitors, emphasizing the importance of fully understanding the function of these and similar treatments used in the clinic at the cellular and molecular level.

The new era in the treatment of advanced colorectal cancer patients: the role of monoclonal antibodies

Colorectal cancer (CRC) represents a major health problem in the Western world. Approximately 60% of patients with CRC require systemic therapy for metastatic disease, either at diagnosis or at disease recurrence. Until recently, classic chemotherapeutic agents have been combined in the treatment of advanced CRC. The recent considerable development of novel monoclonal antibodies that target key components of biological pathways has expanded the options to treat advanced CRC patients. These newer agents more specifically target unique features of the cancer cell and its surroundings and so attempt to exploit the progress that has been made in the understanding of basic cell biology. Two targets in particular--the process of new blood vessel development, or angiogenesis, and the EGF receptor and its signalling pathway--are exploited by the newest monoclonal antibodies available for use in this setting. This clinical review focuses on the defining role of the two most clinically advanced novel agents, bevacizumab and cetuximab in metastatic colorectal cancer.

Targeted Agents for Adjuvant Therapy of Colon Cancer

Among patients with colorectal cancer (CRC) diagnosed in the United States, 37.2% are diagnosed with stage III and 27.9% with stage II disease. In locoregionally advanced CRC, surgery is the primary treatment modality and has a curative intent. The survival depends on the pathologic stage and varies from 30%-60% for stage III to 60%-80% for stage II. However, as much as 40%-50% of patients will relapse and require additional treatment of the disease. Clinical failure after resection of CRC is predominantly secondary to the clinical progression of previously undetected distant metastatic disease. Until very recently, the absolute benefit for survival obtained with adjuvant therapy compared with control was about 6%. Introduction of oxaliplatin in the adjuvant setting has shown a reduction of 23% in the risk of relapse when compared with 5-fluorouracil alone (MOSAIC). Recent phase III studies have shown that targeted agents improved survival in patients with advanced-stage CRC. Bevacizumab, a monoclonal antibody targeting vascular endothelial growth factor, is the first antiangiogenic drug to show improved efficacy when used in combination with irinotecan and oxaliplatin for first- and second-line treatment of CRC. Cetuximab, another monoclonal antibody targeting epidermal growth factor receptor, has shown efficacy in third-line therapy and promising results in first-line phase II studies. There is great interest in whether the biologic agents bevacizumab and cetuximab can improve survival in the adjuvant-therapy setting. This article reviews the adjuvant therapy for colon cancer and discusses the potential role and current trials involving the targeted agents.

Targeted therapy of colorectal cancer: clinical experience with bevacizumab

Advanced colorectal cancer remains an urgent health concern, despite improvements in systemic chemotherapy. Targeted therapeutics promise effective tumor therapy with minimal side effects. Angiogenesis (the formation of new blood vessels) is essential for tumor growth and metastasis and may be an ideal target in the search for new antineoplastic agents. Vascular endothelial growth factor is one of the best characterized of the proangiogenic growth factors that regulate angiogenesis and is a logical target in colorectal cancer therapy. Bevacizumab (Avastin; Genentech Inc.; South San Francisco, CA), a humanized murine monoclonal antibody directed at vascular endothelial growth factor, is being evaluated in the treatment of various types of cancer. It has shown promising efficacy in phase II clinical trials in patients with metastatic colorectal cancer. Addition of bevacizumab at a dose of 5 mg/kg to chemotherapy (5-fluorouracil plus leucovorin) resulted in a higher objective response rate (40% versus 17%), longer time to disease progression (9.0 versus 5.2 months), and longer median survival time (21.5 versus 13.8 months). Hypertension and thrombosis were the principal safety concerns, but were manageable. Further phase II/III studies of bevacizumab, administered with 5-fluorouracil plus leucovorin, with or without irinotecan and/or oxaliplatin, in colorectal cancer, are under way.