Antiangiogenic Monoclonal Antibody Research Articles

Targeted Therapy for Gastric Cancer

For patients with advanced gastric cancer, traditional double or triplet cytotoxic chemotherapy regimens result in a median survival of 9-11 months. As combination therapy is associated with increased survival, but also increased toxicity in a patient population whose performance status often compromised by their malignancy, development of more effective and less toxic treatment choices is mandated. Emerging data from gene expression profiling suggests that differences in pathological appearance and clinical behavior may be due the presence of unique molecular phenotypes. Characterization of the gastric cancer genomic landscape reveals the presence of multiple alterations in expression of receptor tyrosine kinases, which in conjunction with their ligands and downstream effector molecules represent potentially druggable pathways for future drug development. Treatment of HER2 positive gastric cancer with trastuzumab has led to significant gains in overall survival, and further manipulation of this pathway using the novel anti-HER2 directed agents pertuzumab and T-DM1 in addition to dual EGFR/HER2 blockade with lapatinib may yield positive results. In contrast, targeting of the EGFR pathway in combination with chemotherapy in unselected patients has not been fruitful to date, with no significant gains over standard chemotherapy yet demonstrated. Similarly, use of the anti-angiogenic monoclonal antibody bevacizumab was not successful in a large global randomized trial; however intriguing regional variations were seen with respect to efficacy of this drug, leading to calls for a second, regionally stratified study. Careful selection of patient subsets will become a key factor in future clinical trials, as novel targeted agents such as those targeting the MET/HGF and FGFR axes move forward into clinical development. It is hoped that treatment of patients in such molecularly defined groups is will lead to significant gains in survival compared to current treatment paradigms.

Long-term stability of bevacizumab repackaged in 1 mL polypropylene syringes for intravitreal administration

The anti-angiogenic monoclonal antibody, bevacizumab, is currently used by intravitreal administration as off-label drug to treat age-related macular degeneration or other ophthalmologic diseases. For this purpose, commercial bevacizumab is repackaged in 1mL polypropylene syringes under sterile conditions. However, no complete study on the stability of this hospital-based preparation is available. Commercial bevacizumab (25mg/mL; Avastin(®)) was aseptically repackaged in 1mL polypropylene syringes, stored at 4°C, and analyzed within the preparation day (D0), after 30 days (D30) and 90 days (D90). Some syringes were kept for up to 8 months to observe possible instability. Several complementary and stability-indicating analytical methods were used to assess in details the primary, secondary and tertiary structure of the antibody during its conservation: ionic chromatography, size-exclusion chromatography, peptide mapping, 2nd derivative UV and IR spectroscopy, turbidimetry, diffraction laser spectroscopy, thermal denaturation curves, microscopic examination and image analysis. We clearly demonstrate that the commercial solution of bevacizumab can be safely repackaged in polypropylene syringes and stored up to 3 months at 4°C without alteration of its primary, secondary and tertiary structure. The only difference observed is the contamination of the syringe content by silicone oil microdroplets, which is quite immediate and does not change significantly during the storage in terms of number and size. Our results support the off-label use of repackaged bevacizumab by intravitreal administration, at least from a pharmaceutical point of view, with a validated stability of 3 months. This stability period is largely enough to practical situations and support current practices, such as in advance or batch preparations, which present major advantages in terms of GMP respect, workload optimization and financial savings.

Production and quality control of [166Ho]-DOTA-bevacizumab for therapeutic applications

Antiangiogenic monoclonal antibodies in combination with therapeutic radionuclides are potential targeted therapy agents in cancer. In this study, bevacizumab was successively labeled with [166Ho]HoCl3 after conjugation with DOTA-NHS-ester with a radiochemical purity of higher than 95% (RTLC). The conjugates were purified by molecular filtration, the average number of DOTA conjugated per mAb was calculated and total concentration was determined by spectrophotometric method and the average chelate to antibody ratio (c/a) for the conjugate used in this study was 5.8:1 and protein integrity experiments (SDS-PAGE). The biodistribution studies in wild-type rats demonstrate a similar pattern to the other radiolabeled anti-vascular endothelial growth factor A (VEGF-A) immunoconjugates. 166Ho-DOTA-bevacizumab is a potential compound for therapy/imaging of VEGF-A expression in oncology.

Role of biological targeted therapies in gastroenteropancreatic neuroendocrine tumours

Approximately two-thirds of neuroendocrine tumours (NET) occur in the gastrointestinal tract and over 60% present with metastases. With greater insight into molecular pathways involved in tumour progression, opportunities are presented for the use of targeted therapies in NET. Although a wide array of targeted agents has been investigated, only a handful has emerged as forerunners from recent clinical trials. This literature review focuses on the use of anti-angiogenic monoclonal antibody bevacizumab, as well as small molecule inhibitors sunitinib and everolimus.

Prognostic significance of angiogenesis and angiogenic growth factors in nonsmall cell lung cancer.

Currently, nonsmall-cell lung cancer (NSCLC) is the leading cause of cancer-related death in the United States. Angiogenesis, the formation of new vasculature, is a complex and tightly regulated process that promotes metastasis and disease progression in lung cancer and other malignancies. Developmental antiangiogenic agents have shown activity in NSCLC, and bevacizumab, an antiangiogenic monoclonal antibody, is approved for the treatment of patients with advanced disease. However, predictive biomarkers are needed to guide the administration of antiangiogenic agents. It is possible that angiogenic molecules could accurately predict patient response to targeted antiangiogenic therapies, which would allow individualized and perhaps more effective treatment. Angiogenic signaling molecules may also have value as prognostic indicators, which may be useful for the management of NSCLC. Here the author provides an overview of angiogenic molecules currently being investigated as prognostic biomarkers in NSCLC and discusses their potential to guide treatment choices.

Abstract 2412: Sorafenib can be effectively combined with GM-CSF secreting cellular immunotherapy in a mouse model of HER-2+ breast cancer

Abstract Due to the complexities of the tumor microenvironment and the frequent emergence of drug resistance with treatment, it is increasingly evident that cancer therapy will have to hit multiple host and tumor targets simultaneously. We previously reported that DC101, an antiangiogenic monoclonal antibody specific for the vascular endothelial growth factor receptor-2 (VEGFR-2), can enhance tumor immunity by a T cell-dependent mechanism. Sorafenib, a small molecule that also disrupts angiogenesis, blocks signaling through multiple kinases that control tumor growth and progression. It has also been reported to inhibit both dendritic cell (DC) and T cell function. To further explore the intrinsic tumor- and host-based effects of sorafenib, we tested it against murine HER-2+ breast tumor cells (NT) in vitro, and in NT-tumor-bearing FVB/N (immune-competent) and neu-N (immune tolerant to HER-2) mice in vivo. Sorafenib inhibited the growth of NT tumor cells in vitro, inducing apoptosis. Western blot analysis revealed that Sorafenib interfered with ERK/MAPK, but not AKT, signaling pathways, both of which are constitutively activated when HER-2 is over-expressed. Single agent sorafenib effectively controlled the growth of established tumors in immune competent FVB/N mice, but did not result in complete tumor clearance. In contrast, sorafenib alone did not significantly impact the outgrowth of established tumors in neu-N mice, where tumor-specific immune tolerance is in play. Consistent with this observation, depletion studies conducted in immune competent FVB/N mice revealed that the control of tumor growth is in part dependent on T cells, but not macrophages or NK cells. While sorafenib treatment alone did not induce immunity specific for RNEU420–429 (the immunodominant HER-2 epitope), it did accelerate tumor clearance induced by vaccination with a granulocyte-macrophage colony-simulating factor (GM-CSF)-secreting, HER-2+ cellular vaccine in tumor-bearing FVB/N mice compared to either drug treatment or vaccination alone. Finally, sorafenib neither augmented nor inhibited the vaccine-induced T cell response specific for RNEU420–429 as measured by ELISPOT and intracellular cytokine staining. Overall, these findings suggest that vaccine-based immunotherapy can interact with kinase inhibitors by distinct mechanisms for enhanced therapeutic response. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2412.

Site-Specific and Stoichiometric Conjugation of Cationic Porphyrins to Antiangiogenic Monoclonal Antibodies

Synthesis of three new cationic thiol-reactive maleimide-porphyrin derivatives and their use in site-specific conjugation to monoclonal antibodies is reported. The selective reactivity toward thiols is demonstrated using competition experiments, where both thiols and amines are present. This selectivity was used to successfully achieve specific conjugation of two porphyrins to cysteine residues present in the antiangiogenic antibody L19, expressed in small immunoprotein (SIP) format. The effect of length and hydrophilicity of the linkage between porphyrin and maleimide was also investigated, and maximum photocytotoxicity was achieved with the longest and most hydrophilic chain. Immunoreactivity and in vitro photocytotoxicity for these well-characterized porphyrin-antibody conjugates are described.

Antiangiogenesis Targeting Tumor Microenvironment Synergizes Glucuronide Prodrug Antitumor Activity

This study is aimed at investigating the in vivo antitumor activity of a novel cell-impermeable glucuronide prodrug, 9-aminocamptothecin glucuronide (9ACG), and elucidating the synergistically antitumor effects of antiangiogenesis therapy by targeting the tumor microenvironment. We analyzed the antitumor effects of 9ACG alone or combined with antiangiogenic monoclonal antibody DC101 on human tumor xenografts by measuring tumor growth and mouse survival in BALB/c nu/nu nude and NOD/SCID mice. The drug delivery, immune response, and angiogenesis status in treated tumors were assessed by high performance liquid chromatography, immunohistochemistry, and immunofluorescence assays. We developed a nontoxic and cell-impermeable glucuronide prodrug, 9ACG, which can only be activated by extracellular beta-glucuronidase to become severely toxic. 9ACG possesses potent antitumor activity against human tumor xenografts in BALB/c nu/nu nude mice but not for tumors implanted in NOD/SCID mice deficient in macrophages and neutrophils, suggesting that these cells play an important role in activating 9ACG in the tumor microenvironment. Most importantly, antiangiogenic monoclonal antibody DC101 potentiated single-dose 9ACG antitumor activity and prolonged survival of mice bearing resistant human colon tumor xenografts by providing strong beta-glucuronidase activity and prodrug delivery through enhancing inflammatory cell infiltration and normalizing tumor vessels in the tumor microenvironment. We also show that inflammatory cells (neutrophils) were highly infiltrated in advanced human colon cancer tissues compared with normal counterparts. Our study provides in vivo evidence that 9ACG has potential for prodrug monotherapy or in combination with antiangiognesis treatment for tumors with infiltration of macrophage or neutrophil inflammatory cells.

Tumor Recovery by Angiogenic Switch from Sprouting to Intussusceptive Angiogenesis after Treatment with PTK787/ZK222584 or Ionizing Radiation

Inhibitors of angiogenesis and radiation induce compensatory changes in the tumor vasculature both during and after treatment cessation. To assess the responses to irradiation and vascular endothelial growth factor-receptor tyrosine kinase inhibition (by the vascular endothelial growth factor tyrosine kinase inhibitor PTK787/ZK222854), mammary carcinoma allografts were investigated by vascular casting; electron, light, and confocal microscopy; and immunoblotting. Irradiation and anti-angiogenic therapy had similar effects on the tumor vasculature. Both treatments reduced tumor vascularization, particularly in the tumor medulla. After cessation of therapy, the tumor vasculature expanded predominantly by intussusception with a plexus composed of enlarged sinusoidal-like vessels containing multiple transluminal tissue pillars. Tumor revascularization originated from preserved alpha-smooth muscle actin-positive vessels in the tumor cortex. Quantification revealed that recovery was characterized by an angiogenic switch from sprouting to intussusception. Up-regulated alpha-smooth muscle actin-expression during recovery reflected the recruitment of alpha-smooth muscle actin-positive cells for intussusception as part of the angio-adaptive mechanism. Tumor recovery was associated with a dramatic decrease (by 30% to 40%) in the intratumoral microvascular density, probably as a result of intussusceptive pruning and, surprisingly, with only a minimal reduction of the total microvascular (exchange) area. Therefore, the vascular supply to the tumor was not severely compromised, as demonstrated by hypoxia-inducible factor-1alpha expression. Both irradiation and anti-angiogenic therapy cause a switch from sprouting to intussusceptive angiogenesis, representing an escape mechanism and accounting for the development of resistance, as well as rapid recovery, after cessation of therapy.

Randomized, double-blind, placebo-controlled, phase III study of bevacizumab with docetaxel or docetaxel with placebo as first-line therapy for patients with locally recurrent or metastatic breast cancer (mBC): AVADO.

LBA1011 Background: BV (Avastin®), an anti-angiogenic monoclonal antibody that prevents the biologic activity of VEGF, significantly improves overall (OS) and/or progression-free survival (PFS) in four tumour types. In patients with mBC, the phase III study E2100 demonstrated that BV in combination with paclitaxel as 1st-line therapy resulted in superior PFS compared with paclitaxel alone (hazard ratio [HR] = 0.48 as per independent review).The AVADO study investigated the combination of BV and D as first-line therapy in patients with locally recurrent or mBC. Methods: This randomised, double-blind phase III study compared D 100mg/m2 plus PL with D plus either BV 7.5mg/kg or BV 15mg/kg. D was administered q3w for up to 9 cycles. BV/PL was administered q3w until disease progression or unacceptable toxicity. The 1° endpoint was PFS, with 2° endpoints of OS, time to treatment failure, best overall response, duration of response, and safety. Key eligibility criteria were HER2-negative, inoperable locally recurrent or mBC; no prior chemotherapy for advanced disease; ECOG PS 0–1; adequate LVEF, and no CNS metastases. Statistical assumptions: 80% power for a 2-sided unstratified log-rank test to detect a HR for PFS of 0.7, for each BV arm compared with the PL arm (overall α=5%). Results: March 2006 to April 2007, 736 patients in 24 countries were randomised. With median follow-up of ∼11 months PFS was statistically significantly superior for both BV containing arms compared with D alone. ORR was superior in both combination arms relative to D alone. OS is immature due to short follow up. Conclusions: Both doses of BV in combination with D significantly improved PFS and RR compared with D alone. BV added limited incremental toxicity relative to control. Safety results were comparable on the two BV arms and the overall findings did not reveal any new safety signals. D + PL D + BV7.5mg/kg D + BV15mg/kg All randomised patients (n) 241 248 247 PFS Unstratified HR vs D + PL (95% CI) 0.79 (0.63, 0.98) 0.72 (0.57,0.90) p-value (log-rank test)* 0.0318 0.0099 Stratified HR vs D + PL† (95% CI) 0.69 (0.54, 0.89) 0.61 (0.48, 0.78) p-value (log-rank test)* 0.0035 0.0001 Response rate (CR + PR) (%)‡ 44.4 - 55.2 63.1 p- value vs D + PL 0.0295 0.0001 Safety population (n) 233 250 247 Grade ≥3 adverse events (%) 67.0 74.8 74.1 Grade ≥3 hypertension (%) 1.3 0.4 3.2 Grade ≥3 arterial thromboembolic events (%) 0.4 − 0.4 − 0.4 Grade ≥3 GI perforation (%) 0.9 0.8 − 16.6 Grade ≥3 CHF (%) − 12.0 15.2 Grade ≥3 febrile neutropenia (%) Any grade 5 adverse event (up to 21 days after last dose) (%) 2.6 1.6 1.6 *p-values adjusted for multiple testing †pre-specified stratifiedanalysis with censoring for additional anti-neoplastic therapy that started prior to Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Roche Roche, sanofi-aventis Roche Roche, sanofi-aventis Roche Roche, sanofi-aventis

Endocrine and targeted treatments for breast cancer

Endocrine and targeted treatments for breast cancer

HuLuc63 in Combination Regimens with Conventional and Targeted Therapies Has Additive and Synergistic Anti-Tumor Activity in Pre-Clinical Models of Myeloma.

Introduction: HuLuc63 is a humanized monoclonal antibody that targets CS1 (CD2 subset 1, CRACC, SLAMF7, CD319), a cell surface glycoprotein that is highly and universally expressed on myeloma cells. In preclinical studies, we have shown that HuLuc63 treatment of mice with multiple myeloma (MM) xenograft tumors resulted in significant in vivo anti-tumor activity that is mediated at least in part by an antibody-dependent cellular cytotoxicity (ADCC) mechanism of action. The purpose of this study was to examine whether using HuLuc63 in combination with a panel of drugs having distinct modes of action (dexamethasone, thalidomide, bevacizumab (Avastin®), bortezomib (Velcade®)) could result in additional therapeutic benefit and provide a rationale for the design of future clinical trials.Methods: HuLuc63 in combination with other agents was tested in vivo for anti-tumor activity using the human L363 and OPM2 xenograft models. SCID mice were implanted subcutaneously with myeloma cells and randomized into different groups (10–15 mice per treatment group) when the average tumor volume reached ∼100 mm3. HuLuc63 was administered via intra-peritoneal injection twice per week at doses of 1–10 mg/kg. Dosing for dexamethasone was 10 mg/kg twice weekly, thalidomide 50 mg/kg daily, bevacizumab twice weekly at 0.5 mg/kg, and bortezomib 1 mg/kg for two dosing cycles, each cycle consisting of twice weekly dosing for 2 weeks followed by a week of rest.Results: The combination of dexamethasone with HuLuc63 showed a statistically significant increase in anti-tumor activity over either agent alone (p < 0.04). Combination with thalidomide only showed a slight enhancement of tumor inhibition when dosed in combination with HuLuc63 but its anti-tumor activity did not reach a statistically significant increase in over that of HuLuc63 alone. Co-treatment of the anti-VEGF anti-angiogenic monoclonal antibody bevacizumab with HuLuc63 resulted in a significant increase in tumor inhibition (p < 0.05) over that observed with either antibody when used as a single agent. The strongest anti-myeloma activity was observed when HuLuc63 was combined with bortezomib, which appeared to result in a synergistic inhibition of tumor cell growth. None of the agents tested changed the CS1 expression level on the myeloma cells or diminished the anti-myeloma activity of HuLuc63.Conclusions: These results suggest that HuLuc63 may be combined with different classes of drugs to enhance its anti-myeloma effects. In particular, agents that may induce apoptosis of myeloma cells (dexamethasone and bortezomib) and anti-angiogenics (bevacizumab) may be of particular interest for future clinical testing. Further preclinical studies using HuLuc63 in combination with other agents are in progress. HuLuc63 is currently being evaluated in a phase I clinical study as monotherapy for the treatment of relapsed/refractory multiple myeloma.

A Vascular Endothelial Growth Factor Receptor-2 Inhibitor Enhances Antitumor Immunity through an Immune-Based Mechanism

Given the complex tumor microenvironment, targeting multiple cellular components may be the most effective cancer treatment strategy. Therefore, we tested whether antiangiogenic and immune-based therapy might synergize by characterizing the activity of DC101, an antiangiogenic monoclonal antibody specific for vascular endothelial growth factor receptor-2 (VEGF-R2), alone and with HER-2/neu (neu)-targeted vaccination. Neu-expressing breast tumors were measured in treated nontolerant FVB mice and immune-tolerant neu transgenic (neu-N) mice. Neu-specific and tumor cell-specific immune responses were assessed by intracellular cytokine staining, ELISPOT, and CTL assays. DC101 decreased angiogenesis and increased tumor cell apoptosis. Although DC101 increased serum levels of the immunosuppressive cytokine VEGF, no evidence of systemic immune inhibition was detected. Moreover, DC101 did not impede the influx of tumor-infiltrating lymphocytes. In FVB mice, DC101 inhibited tumor growth in part through a T cell-dependent mechanism, resulting in both increased tumor-specific CD8(+) T cells and tumor regression. Combining DC101 with neu-specific vaccination accelerated tumor regression, augmenting the lytic activity of CD8(+) cytotoxic T cells. In tolerant neu-N mice, DC101 only delayed tumor growth without inducing frank tumor regression or antigen-specific T-cell activation. Notably, mitigating immune tolerance by inhibiting regulatory T cell activity with cyclophosphamide revealed DC101-mediated augmentation of antitumor responses in vaccinated neu-N mice. This is the first report of DC101-induced antitumor immune responses. It establishes the induction of tumor-specific T-cell responses as one consequence of VEGF-R2 targeting with DC101. These data support the development of multitargeted cancer therapy combining immune-based and antiangiogenic agents for clinical translation.

The Advanced Renal Cell Carcinoma Sorafenib (ARCCS) expanded access trial: Safety and efficacy in patients (pts) with prior bevacizumab (BEV) treatment

5041 Background: Sorafenib (SOR) is an oral multi-kinase inhibitor of tumor-cell angiogenesis and proliferation. Phase III (TARGETs) data have demonstrated prolonged progression-free survival in pts with advanced clear cell renal cell carcinoma (RCC) in whom prior therapy failed. Activity of SOR following treatment with BEV, an anti-vascular endothelial growth factor and antiangiogenic monoclonal antibody, has not been evaluated. Methods: A subset analysis was conducted to describe safety and efficacy in the SOR expanded access program in North America for pts receiving prior BEV. Inclusion criteria for this open-label, nonrandomized trial included advanced RCC; ineligibility for, or lack of access to, other SOR clinical trials; age =15 years; ECOG PS of 0–2; recovery from prior treatment; adequate prior treatment of brain metastases. Major exclusion criteria included life expectancy &lt;2 months; active coronary artery disease, ischemia or hypertension; severe renal impairment requiring dialysis. Pts previously treated with BEV required =28 days from last dose, no =Grade 3 hemorrhagic episode during therapy, and no history of =Grade 2 hemorrhagic event 6 mos prior to BEV treatment. Results: Of the 2,488 pts in ARCCS valid for safety analysis, 289 pts had received prior BEV: 65% male with median age 61 yrs. Grade 3 and 4 toxicities occurring in &gt;2% of prior BEV pts included hand-foot skin reaction 9.0%; fatigue 6.9%; hypertension 4.8%; dehydration, dyspnea, anorexia, and abdominal pain 3.1%; back pain, rash/desquamation, and mucositis 2.8%; pleural effusion and diarrhea 2.1%. Of the 195 BEV-pretreated pts evaluable for response, 152 (77.5%) had stable disease and 5 (2.5%) had confirmed partial responses (PR). There were 26 (13.3%) unconfirmed PRs reported according to RECIST, 4 of which missed a second scan due to US ARCCS enrollment ceasing upon FDA approval of SOR in 12/05. Conclusions: We observed activity of SOR following BEV therapy for advanced RCC. AEs in this subset were generally well tolerated and similar to those in the overall ARCCS population. Further investigation is warranted to elucidate mechanisms for response to SOR following prior antiangiogenic treatment. [Table: see text]

Pharmacokinetics and safety of bevacizumab administered in combination with cisplatin and paclitaxel in cynomolgus monkeys

Bevacizumab is the first anti-angiogenic monoclonal antibody approved for use in combination with chemotherapy for treatment of a variety of solid tumors. The objective of this study was to evaluate the safety of bevacizumab when administered concomitantly with paclitaxel and cisplatin to cynomolgus monkeys, and to assess the pharmacokinetic and safety interactions between bevacizumab and the two chemotherapeutic agents. Twenty male cynomolgus monkeys (Macaca fasicularis) were randomized to one of four treatment groups: vehicle, bevacizumab alone, cisplatin alone, and the combination of cisplatin and bevacizumab. Blood collection over serial time points allowed determination of the pharmacokinetic parameters of paclitaxel and bevacizumab and the maximum concentration (C (max)) for cisplatin. Drug concentrations were determined by graphite-furnace atomic absorption, high performance liquid chromatography, and enzyme-linked immunosorbent assay methods, for cisplatin, paclitaxel, and bevacizumab, respectively. AUC0-t values for bevacizumab when administered alone or in combination with chemotherapy were 6,747 +/- 1,872 and 7,366 +/- 1,599 microg/ml x day, respectively. AUC0-t values for paclitaxel with or without concomitantly administered bevacizumab were 10.9 +/- 2.9 and 10.3 +/- 3.7 microg/ml x day, respectively. No alterations in the C (max) of bevacizumab, paclitaxel, or cisplatin were observed between any of the treatment groups. As expected, based on their known safety profile, the administration of cisplatin and paclitaxel were associated with vomiting, decreased body weight, and transient decreases in white blood cell and absolute neutrophil counts; concomitant bevacizumab administration did not alter the incidence or severity of these toxicological effects. Pharmacokinetic estimates for bevacizumab, paclitaxel and cisplatin indicate that combination of bevacizumab with the two chemotherapeutic agents does not result in a pharmacokinetic interaction. Moreover, the addition of bevacizumab to the chemotherapy regimen did not appear to alter the safety profiles of cisplatin/paclitaxel in cynomolgus monkeys. Results from the present study supported the clinical development of bevacizumab treatment regimens in combination with the chemotherapeutic agents paclitaxel and cisplatin.

Bevacizumab, a humanized anti-angiogenic monoclonal antibody for the treatment of colorectal cancer

Angiogenesis is the process by which new blood vessels are created from pre-existing vessels. It is essential for the growth and development of normal cells and tissues during embryonic and neonatal development and of tumour cells. Solid tumours rely on having an extensive network of blood vessels for growth and survival. The key mediator of angiogenesis, vascular endothelial growth factor-A (VEGF-A), is critical for the growth of tumours and their subsequent metastasis and is known to initiate angiogenesis. Bevacizumab is a humanized immunoglobulin G monoclonal antibody that binds to VEGF with high specificity, thereby blocking VEGF-mediated signalling pathways and thus angiogenesis. Clinical trials have shown that bevacizumab is effective in prolonging survival in patients with metastatic colorectal cancer (CRC) when combined with standard chemotherapy. Consequently, bevacizumab has been approved in combination with 5-fluorouracil-based chemotherapy for first-line treatment of patients with metastatic CRC. Bevacizumab is generally well tolerated in most patients and does not exacerbate the adverse events associated with conventional chemotherapy. Bevacizumab-related side effects are generally manageable; however, monitoring for hypertension, gastrointestinal perforation, bleeding, proteinuria and thromboembolism is advised, especially in patients with predisposing factors. In addition to demonstrated survival benefits, the convenient dosing schedule and lack of interactions should ensure the successful integration of this novel agent into clinical practice.

Angiogenesis and antiangiogenic treatment in lung cancer

Angiogenic factors released by cancer cells increase structurally and functionally abnormal tumor micro-vascularization, resulting in metastases and progressive disease. Such diffusible factors bind to specific receptors of endothelial cells and activate the angiogenic signal pathway. Treatments with antiangiogenic monoclonal antibodies (e.g., bevacizumab) or using small molecules with anti-tyrosine kinase activity (e.g., sunitinib, sorafenib, ZD6474, erlotinib, or thalidomide) can block angiogenic signaling, lower blood tumoral irrigation, and improve chemotherapy distribution. Numerous studies have shown that a combination of biotherapy and chemotherapy can improve medical management of patients with advanced or metastatic non-small cell lung carcinomas. Biotherapy combination approaches also yield encouraging results promoting the development of targeted antitumor drugs.

The influence of cellular seeding density in the microencapsulation of hybridoma cells

The aim of this study was to assess the influence of different seeding densities on the function of hybridoma cells (clone 1B5, IgG 2 α) producing an anti-angiogenic monoclonal antibody (mAb), microencapsulated using a high-voltage electrostatic field. Viable cells were microencapsulated in alginate/poly-L-lysine/alginate (APA) capsules and maintained in tissue culture. Cellular growth rates, production and release of mAb from the capsules were assessed. This study shows that hybridoma cells survive, proliferate and remain functionally competent for over one month in vitro after microencapsulation in APA capsules generated in an electrostatic field. However, the cell seeding density had to be at least 107 cells/ml for the microencapsulated cells to be viable and to produce and release mAb through the capsule membrane. The maximum monoclonal antibody concentration in this culture was 29.1 μg/ml by day 17, with a tendency to increase, but capsule breakage impeded the follow-up of this determination.

Pathophysiological effects of vascular endothelial growth factor receptor-2-blocking antibody plus fractionated radiotherapy on murine mammary tumors.

Although clinical trials of antiangiogenic strategies have been disappointing when administered as single agents, such approaches can play an important role in cancer treatment when combined with conventional therapies. Previous studies have shown that DC101, an antiangiogenic monoclonal antibody against vascular endothelial growth factor receptor-2, can produce significant growth inhibition in spontaneous and transplanted tumors but can also induce substantial hypoxia. Because DC101 appears to potentiate radiotherapy in some tumors, the present studies were undertaken to characterize pathophysiological changes following combined therapy and to determine whether radioresponse is enhanced despite the induction of hypoxia. MCa-4 and MCa-35 mammary carcinomas were treated with: (a) DC101; (b) 5 x 6 Gy radiation fractions; or (c) the combination. Image analysis of frozen tumor sections was used to quantitate: (a) hypoxia; (b) spacing of total and perfused blood vessels; and (c) endothelial and tumor cell apoptosis. For MCa-4, combination treatment schedules produced significant and prolonged delays in tumor growth, whereas single-modality treatments had minor effects. For MCa-35, radiation or the combination led to equivalent growth inhibition. In all tumors, hypoxia increased markedly after either radiation or DC101 alone. Although combination therapy produced no immediate pathophysiological changes, hypoxia ultimately increased after cessation of therapy. Preferential increases in endothelial apoptosis following combination treatment suggest that in addition to blocking tumor angiogenesis, DC101 enhances radiotherapy by specifically sensitizing endothelial cells, leading to degeneration of newly formed blood vessels.