The effects of ZD6474, an inhibitor of VEGF signaling, on cutaneous wound healing in mice

The Adverse Impact of Tyrosine Kinase Inhibitors on Wound Healing and Repair

Tyrosine kinase inhibitors (TKIs) can treat various cancers, primarily through their antiangiogenic effects. However, as angiogenesis is crucial for successful wound healing, TKIs may adversely impact wound repair. This review analysed all 63 FDA-approved TKIs and identified evidence for wound healing and repair implications in 24 agents. The primary mechanism contributing to impaired wound healing appears to be the inhibition of vascular endothelial growth factor receptors, with secondary targets, such as epidermal growth factor receptors and platelet-derived growth factor receptors, potentially playing a role. Information from safety package inserts, preclinical studies, case reports and clinical trials suggests that these TKIs can cause delayed or impaired wound healing. The safety information generally recommends discontinuing treatment for at least one to 2 weeks before elective surgery and resuming treatment only after adequate wound healing has occurred. Neoadjuvant therapy with TKIs may be feasible if sufficient time is allowed between the cessation of the TKI and the onset of surgery. As the use of TKIs continues to increase, healthcare professionals should be aware of their potential impact on wound healing and take appropriate precautions to minimise the risk of wound-related complications.

Management of Portal Hypertension in Patients with Hepatocellular Carcinoma on Systemic Treatment: Current Evidence and Future Perspectives

The management of CSPH in patients undergoing systemic treatment for HCC has emerged as a critical concern due to the absence of reliable diagnostic criteria and uncertainties surrounding therapeutic approaches. This review aims to underscore the primary pathophysiological aspects linking HCC and PH, while also addressing the current and emerging clinical strategies for the management of portal hypertension. A review of studies from January 2003 to June 2023 was conducted using the PubMed database and employing MeSH terms, such as "hepatocellular carcinoma", "immune checkpoint inhibitors", "systemic therapy", "portal hypertension", "variceal bleeding" and "tyrosine kinase inhibitors". Despite promising results of tyrosine kinase inhibitors in animal models for PH and fibrosis, only Sorafenib has demonstrated similar effects in human studies, whereas Lenvatinib appears to promote PH development. The impact of Atezolizumab/Bevacizumab on PH remains uncertain, with an increasing risk of bleeding related to Bevacizumab in patients with prior variceal hemorrhage. Given the absence of specific guidelines, endoscopic surveillance during treatment is advisable, and primary and secondary prophylaxis of variceal bleeding should adhere to the Baveno VII recommendations. Furthermore, in patients with advanced HCC, refinement of diagnostic criteria for CSPH and guidelines for its surveillance are warranted.

Identification of key genes and pathways in scleral extracellular matrix remodeling in glaucoma: Potential therapeutic agents discovered using bioinformatics analysis

Background: Glaucoma is a leading cause of irreversible blindness. Remodeling of the scleral extracellular matrix (ECM) plays an important role in the development of glaucoma. The aim of this study was to identify the key genes and pathways for the ECM remodeling of sclera in glaucoma by bioinformatics analysis and to explore potential therapeutic agents for glaucoma management. Methods: Genes associated with glaucoma, sclera and ECM remodeling were detected using the text mining tool pubmed2ensembl, and assigned Gene Ontology (GO) biological process terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways using the GeneCodis program. A protein-protein interaction (PPI) network was constructed by STRING and visualized in Cytoscape, module analysis was performed using the Molecular Complex Detection (MCODE) plugin, and GO and KEGG analyses of the gene modules were performed using the Database of Annotation, Visualization and Integrated Discovery (DAVID) platform. The genes that clustered in the significant module were selected as core genes, and functions and pathways of the core genes were visualized using ClueGO and CluePedia. Lastly, the drug-gene interaction database was used to explore drug-gene interactions of the core genes to find drug candidates for glaucoma. Results: We identified 125 genes common to "Glaucoma", "Sclera", and "ECM remodeling" by text mining. Gene functional enrichment analysis yielded 30 enriched GO terms and 20 associated KEGG pathways. A PPI network that included 60 nodes with 249 edges was constructed, and three gene modules were obtained using the MCODE. We selected 13 genes that clustered in module 1 as core candidate genes that were associated mainly with ECM degradation and cell proliferation and division. The HIF-1 signaling pathway, FOXO signaling pathway, PI3K-Akt signaling pathway and TGFB signaling pathway were found to be enriched. We found that 11 of the 13 selected genes could be targeted by 26 existing drugs. Conclusions: The results showed that VEGFA, TGFB1, TGFB2, TGFB3, IGF2, IGF1, EGF, FN1, KNG1, TIMP1, SERPINE1, THBS1, and VWF were potential key genes involved to scleral ECM remodeling. Furthermore, 26 drugs were identified as potential therapeutic agents for glaucoma treatment and management.

VEGF Receptor-2 Activation Mediated by VEGF-E Limits Scar Tissue Formation Following Cutaneous Injury

Objective: Vascular endothelial growth factor (VEGF) family members are critical regulators of tissue repair and depending on their distinct pattern of receptor specificity can also promote inflammation and scarring. This study utilized a receptor-selective VEGF to examine the role of VEGF receptor (VEGFR)-2 in scar tissue (ST) formation. Approach: Cutaneous skin wounds were created in mice using a 4 mm biopsy punch and then treated until closure with purified VEGF-E derived from orf virus stain NZ-2. Tissue samples were harvested to measure gene expression using quantitative PCR and to observe ST formation through histological examination and changes in cell populations by immunofluorescence. Results: VEGFR-2-activation with VEGF-E increased expression of anti-inflammatory cytokine interleukin (IL)-10 and reduced macrophage infiltration and myofibroblast differentiation in wounded skin compared with controls. VEGF-E treatment also increased microvascular density and improved pericyte coverage of blood vessels in the healing wounds. The ST that formed following treatment with VEGF-E was reduced in size and showed improved collagen structure. Innovation: The role of VEGFR-2 activation in wound epithelialization and angiogenesis is well established; but its contribution to ST formation is unclear. This study tests the effect of a selective VEGFR-2 activation on ST formation following cutaneous wounding in a murine model. Conclusion: VEGFR-2 stimulation can enhance the quality of skin repair, at least, in part, through the induction of IL-10 expression and dampening of wound inflammation and fibrosis. Therapies that selectively activate VEGFR-2 may therefore be beneficial to treat impaired healing or to prevent excess scarring.

A phase II trial evaluating the feasibility of adding bevacizumab to standard osteosarcoma therapy

Increased vascular endothelial growth factor (VEGF) expression in osteosarcoma correlates with a poor outcome. We conducted a phase II trial to evaluate the feasibility and efficacy of combining bevacizumab, a monoclonal antibody against VEGF, with methotrexate, doxorubicin and cisplatin (MAP) in patients with localized osteosarcoma. Eligible patients received two courses of MAP chemotherapy before definitive surgery at week 10. Bevacizumab (15 mg/kg) was administered 3 days before starting chemotherapy then on day 1 of weeks 3 and 5 of chemotherapy. After surgery, patients received MAP for a total of 29 weeks; bevacizumab was added every 2 or 3 weeks on day 1 of chemotherapy at least 5 weeks after surgery. Group sequential monitoring rules were used to monitor for unacceptable bevacizumab-related targeted toxicity (grade 4 hypertension, proteinuria or bleeding, grade 3 or 4 thrombosis/embolism, and grade 2-4 major wound complications). Thirty-one patients (median age 12.8 years) with localized osteosarcoma were enrolled. No unacceptable targeted toxicities were observed except for wound complications (9 minor and 6 major), which occurred in 15 patients; none required removal of prosthetic hardware or amputation. The estimated 4-year event-free survival (EFS) rate and overall survival rate were 57.5 ± 10.0% and 83.4 ± 7.8%, respectively. Eight (28%) of 29 evaluable patients had good histologic response (<5% viable tumor) to preoperative chemotherapy. The addition of bevacizumab to MAP for localized osteosarcoma is feasible but frequent wound complications are encountered. The observed histologic response and EFS do not support further evaluation of bevacizumab in osteosarcoma.

Acute cutaneous wounds treated with human decellularised dermis show enhanced angiogenesis during healing

BACKGROUND

The influence of skin substitutes upon angiogenesis during wound healing is unclear.

OBJECTIVES

To compare the angiogenic response in acute cutaneous human wounds treated with autogenic, allogenic and xenogenic skin substitutes to those left to heal by secondary intention.

METHODS

On day 0, four 5mm full-thickness punch biopsies were harvested from fifty healthy volunteers (sites 1-4). In all cases, site 1 healed by secondary intention (control), site 2 was treated with collagen-GAG scaffold (CG), cadaveric decellularised dermis (DCD) was applied to site 3, whilst excised tissue was re-inserted into site 4 (autograft). Depending on study group allocation, healing tissue from sites 1-4 was excised on day 7, 14, 21 or 28. All specimens were bisected, with half used in histological and immunohistochemical evaluation whilst extracted RNA from the remainder enabled whole genome microarrays and qRT-PCR of highlighted angiogenesis-related genes. All wounds were serially imaged over 6 weeks using laser-doppler imaging and spectrophotometric intracutaneous analysis.

RESULTS

Inherent structural differences between skin substitutes influenced the distribution and organisation of capillary networks within regenerating dermis. Haemoglobin flux (p = 0.0035), oxyhaemoglobin concentration (p = 0.0005), and vessel number derived from CD31-based immunohistochemistry (p = 0.046) were significantly greater in DCD wounds at later time points. This correlated with time-matched increases in mRNA expression of membrane-type 6 matrix metalloproteinase (MT6-MMP) (p = 0.021) and prokineticin 2 (PROK2) (p = 0.004).

CONCLUSION

Corroborating evidence from invasive and non-invasive modalities demonstrated that treatment with DCD resulted in increased angiogenesis after wounding. Significantly elevated mRNA expression of pro-angiogenic PROK2 and extracellular matrix protease MT6-MMP seen only in the DCD group may contribute to observed responses.

Systemic thromboembolic adverse events in patients treated with intravitreal anti-VEGF drugs for neovascular age-related macular degeneration: an overview

INTRODUCTION

Anti-VEGF therapy improved the quality of life for millions of patients suffering from wet age-related macular degeneration (wet-AMD); unfortunately, this therapy involves multiple injections over many years. The administration of anti-VEGF can overcome the blood-retinal barrier with agents entering the systemic circulation and causing a significant decrease in VEGF serum concentration. Although circulating VEGF protects the integrity and patency of vessels, prolonged anti-VEGF treatment has the potential to increase the risk of thromboembolic events.

AREAS COVERED

In this review, we discuss the safety data from recent trials involving available anti-VEGF drugs.

EXPERT OPINION

During the 2 years of follow-up in the relevant clinical trials, the rates of serious adverse events such as stroke, heart attack and death were similar for patients treated with different anti-VEGF drugs. Moreover the arterial thrombotic risk appears sufficiently low when compared with the natural incidence of arterial thrombotic events in this category of elderly patients and acceptably balanced against the advantage of improved vision. Since the use of these drugs is likely to become increasingly widespread and prolonged, it is desirable that the scientific community improves the pharmacovigilance program on all anti-VEGF drugs, expanding knowledge with studies that compares head to head all four compounds belonging to anti-VEGF armamentarium.

Current understanding of molecular and cellular mechanisms in fibroplasia and angiogenesis during acute wound healing

Cutaneous wound healing ultimately functions to facilitate barrier restoration following injury-induced loss of skin integrity. It is an evolutionarily conserved, multi-cellular, multi-molecular process involving co-ordinated inter-play between complex signalling networks. Cellular proliferation is recognised as the third stage of this sequence. Within this phase, fibroplasia and angiogenesis are co-dependent processes which must be successfully completed in order to form an evolving extracellular matrix and granulation tissue. The resultant structures guide cellular infiltration, differentiation and secretory profile within the wound environment and consequently have major influence on the success or failure of wound healing. This review integrates in vitro, animal and human in vivo studies, to provide up to date descriptions of molecular and cellular interactions involved in fibroplasia and angiogenesis. Significant molecular networks include adhesion molecules, proteinases, cytokines and chemokines as well as a plethora of growth factors. These signals are produced by, and affect behaviour of, cells including fibroblasts, fibrocytes, keratinocytes, endothelial cells and inflammatory cells resulting in significant cellular phenotypic and functional plasticity, as well as controlling composition and remodelling of structural proteins including collagen and fibronectin. The interdependent relationship between angiogenesis and fibroplasia relies on dynamic reciprocity between cellular components, matrix proteins and bioactive molecules. Unbalanced regulation of any one component can have significant consequences resulting in delayed healing, chronic wounds or abnormal scar formation. Greater understanding of angiogenic and fibroplastic mechanisms underlying chronic wound pathogenesis has identified novel therapeutic targets and enabled development of improved treatment strategies including topical growth factors and skin substitutes.

Angiogenesis and scar formation in healing wounds

PURPOSE OF REVIEW

One well described feature of wound healing is the ingrowth of new capillaries or angiogenesis. At its peak, the capillary content in healing wounds may reach three or more times that of normal uninjured tissue. This new vasculature is required to restore oxygenation and allow the growth of new tissue to fill the wound space. This review examines the assumption that a capillary content in excess of normal density is essential for adequate healing.

RECENT FINDINGS

The regulation of wound angiogenesis has been demonstrated to involve both proangiogenic and antiangiogenic stimuli, with the level of capillary growth reliant upon both sets of factors. Several studies now show that normal skin wounds heal adequately even when the angiogenic response is artificially reduced. In normal skin, a reduction of capillary growth to a level consistent with normal tissue does not affect wound closure and may even lead to highly favorable long term healing outcomes.

SUMMARY

The angiogenic response in normal wounds may exceed what is needed for optimal repair.

Neoadjuvant bevacizumab persistently inactivates VEGF at the time of surgery despite preoperative cessation

BACKGROUND

When anti-VEGF (vascular endothelial growth factor) antibody bevacizumab is applied in neoadjuvant treatment of colorectal cancer patients with liver metastasis, 5-6 weeks between last bevacizumab dose and liver resection are currently recommended to avoid complications in wound and liver regeneration. In this context, we aimed to determine whether VEGF is inactivated by bevacizumab at the time of surgery.

METHODS

Fifty colorectal cancer patients with liver metastases received neoadjuvant chemotherapy ± bevacizumab supplementation. The last dose of bevacizumab was administered 6 weeks before surgery. Plasma, subcutaneous and intraabdominal wound fluid were analysed for VEGF content before and after liver resection (day 1-3). Immunoprecipitation was applied to determine the amount of bevacizumab-bound VEGF.

RESULTS

Bevacizumab-treated individuals showed no increase in perioperative complications. During the entire monitoring period, plasma VEGF was inactivated by bevacizumab. In wound fluid, VEGF was also completely bound by bevacizumab and was remarkably low compared with the control chemotherapy group.

CONCLUSION

These data document that following a cessation time of 6 weeks, bevacizumab is fully active and blocks circulating and local VEGF at the time of liver resection. However, despite effective VEGF inactivation no increase in perioperative morbidity is recorded suggesting that VEGF activity is not essential in the immediate postoperative recovery period.

Perioperative polyphenon E- and siliphos-inhibited colorectal tumor growth and metastases without impairment of gastric or abdominal wound healing in mouse models

INTRODUCTION

Perioperative anticancer therapy that does not impair wound healing is needed to counter the persistent proangiogenic plasma compositional changes that occur after colorectal resection. Polyphenon E (PolyE), a green tea derivative (main component EGCG), and Siliphos (main component silibinin), from the milk thistle plant, both have antitumor effects. This study assessed the impact of PolyE/Siliphos (PES) on wound healing and the growth of CT-26 colon cancer in several murine models.

METHODS

One wound healing and three tumor studies were performed. Tumor Study (TS)1 assessed the impact of PES on subcutaneous tumor growth, whereas TS2 assessed PES's impact on subcutaneous growth when given pre- and post-CO(2) pneumoperitoneum (pneumo), sham laparotomy, or anesthesia alone. TS3 determined the ability of PES to limit hepatic metastases (mets) after portal venous injection of tumor cells. In the final study, laparotomy and gastrotomy wound healing were assessed several ways. BALB/c mice were used for all studies. The drugs were given via drinking water (PolyE) and gavage (Siliphos), daily, for 7-9 days preprocedure and for 7-21 days postoperatively. Tumor mass, number/size of hepatic mets, and proliferation and apoptosis rates were assessed. The abdominal breaking strength and energy to failure were measured postmortem as was gastric bursting pressures.

RESULTS

PES significantly inhibited subcutaneous growth in the nonoperative setting. PES also significantly decreased the number/size of liver mets when given perioperatively. Abdominal wound breaking strength, energy to wound failure, and collagen content were not altered by PES; gastrotomy bursting strength also was not affected by PES. Neither drug alone had a significant impact on tumor growth.

CONCLUSIONS

The PES combination inhibited subcutaneous and hepatic tumor growth yet did not impair wound healing. PES holds promise as a perioperative anticancer therapy.

Feasibility and efficacy of neoadjuvant sunitinib before nephron-sparing surgery

OBJECTIVE

To investigate efficacy of neoadjuvant tyrosine kinase-inhibitor therapy (TKI) before imperative nephron-sparing surgery (NSS), as NSS in patients with large locally advanced or centrally located tumours can be challenging, and TKI therapy might result in a reduction of primary tumour burden and increase the feasibility of NSS.

PATIENTS AND METHODS

This was a multicentre retrospective review and prospective pilot study of patients undergoing neoadjuvant sunitinib before planned NSS from February 2006 to February 2009. All patients underwent confirmatory biopsy for clear cell renal cell carcinoma. Patients received two 28-day cycles of sunitinib before NSS. Demographics/tumour characteristics, tumour response (by the Response Evaluation Criteria In Solid Tumors), outcomes and complications were analysed.

RESULTS

Twelve patients (seven men and five women; mean age 60.1 years, tumours on 14 renal units) were given TKI before NSS for imperative indications. The mean pretreatment tumour diameter was 7.1 cm; all patients had a decrease in size of the primary tumour after TKI, with a mean reduction in maximum diameter of 1.5 cm (21.1%). Four of 14 and 10 of 14 primary tumours had a partial response and stable disease after TKI. NSS was achievable in all 14 kidneys. Four patients had a concurrent metastasectomy. The mean warm ischaemia time was 22.5 min; postoperative dialysis was not required in any patients. Final pathology revealed negative tumour margins in all 14 tumours. The mean creatinine and estimated glomerular filtration rate (before/after NSS) were 1.34/1.40 mg/dL (P = 0.431) and 57.7/53.4 mL/min/1.73 m(2) (P = 0.475), respectively. At a mean follow-up of 23.9 months, 10 of the 12 patients were alive, one died from metastatic RCC and none required dialysis. Three of the 14 renal units developed delayed urinary leaks, all in patients who also received postoperative sunitinib. All leaks resolved with conservative measures.

CONCLUSIONS

Neoadjuvant TKI followed by NSS is safe and feasible, with all patients achieving a reduction in maximum tumour diameter, and with NSS being achievable with negative margins and with no requirement for postoperative dialysis. Further investigation is required.

Dual inhibition of vascular endothelial growth factor receptor and epidermal growth factor receptor is an effective chemopreventive strategy in the mouse 4-NQO model of oral carcinogenesis

Despite recent therapeutic advances, several factors, including field cancerization, have limited improvements in long-term survival for oral squamous cell carcinoma (OSCC). Therefore, comprehensive treatment plans must include improved chemopreventive strategies. Using the 4-nitroquinoline 1-oxide (4-NQO) mouse model, we tested the hypothesis that ZD6474 (Vandetanib, ZACTIMA) is an effective chemopreventive agent. CBA mice were fed 4-NQO (100 μg/mL) in their drinking water for 8 weeks and then randomized to no treatment or oral ZD6474 (25 mg/kg/d) for 24 weeks. The percentage of animals with OSCC was significantly different between the two groups (71% in control and 12% in the ZD6474 group; P ≤ 0.001). The percentage of mice with dysplasia or OSCC was significantly different (96% in the control and 28% in the ZD6474 group; P ≤ 0.001). Proliferation and microvessel density scores were significantly decreased in the ZD6474 group (P ≤ 0.001 for both). Although proliferation and microvessel density increased with histologic progression in control and treatment cohorts, epidermal growth factor receptor and vascular endothelial growth factor receptor-2 phosphorylation was decreased in the treatment group for each histologic diagnosis, including mice harboring tumors. OSCC from ZD6474-treated mice exhibited features of epithelial to mesenchymal transition, as shown by loss E-cadherin and gain of vimentin protein expression. These data suggest that ZD6474 holds promise as an OSCC chemopreventive agent. They further suggest that acquired resistance to ZD6474 may be mediated by the expression of an epithelial to mesenchymal transition phenotype. Finally, the data suggests that this model is a useful preclinical platform to investigate the mechanisms of acquired resistance in the chemopreventive setting.

Cutaneous pigmentation after photosensitivity induced by vandetanib therapy

BACKGROUND

Photosensitivity has been reported in patients who were treated with vandetanib (ZD6474), an inhibitor of epidermal growth factor receptor, vascular endothelial growth factor receptor, and the RET (rearranged during transfection) kinases.

OBSERVATIONS

We describe the occurrence of cutaneous hyperpigmentation after photosensitivity in 2 patients who were treated with vandetanib. The pigmentation patterns were variable within and between patients. Biopsy specimens from different sites revealed variability in Perls and Fontana staining patterns.

CONCLUSIONS

These 2 cases highlight the unusual occurrence of cutaneous hyperpigmentation after vandetanib-associated photosensitivity, a reaction that demonstrates that medications are important causes of acquired photosensitivity and hyperpigmentation. Aggressive photoprotection may facilitate the resolution of diffuse hyperpigmentation. Dermatologists should endeavor to identify and report novel cutaneous adverse effects as new targeted therapies are developed.

RGTA OTR 4120, a heparan sulfate proteoglycan mimetic, increases wound breaking strength and vasodilatory capability in healing rat full-thickness excisional wounds

ReGeneraTing Agents (RGTAs), a family of polymers engineered to protect and stabilize heparin-binding growth factors, have been shown to promote tissue repair and regeneration. In this study, the effects of one of these polymers, RGTA OTR4120, on healing of full-thickness excisional wounds in rats were investigated. Two 1.5 cm diameter circular full-thickness excisional wounds were created on the dorsum of a rat. After creation of the wounds, RGTA OTR4120 was applied. The progress of healing was assessed quantitatively by evaluating the wound closure rate, vasodilatory capability, and wound breaking strength. The results showed a triple increase of the local vascular response to heat provocation in the RGTA OTR4120-treated wounds as compared with vehicle-treated wounds. On days 14 and 79 after surgery, the wounds treated with RGTA OTR4120 gained skin strength 12% and 48% of the unwounded skin, respectively, and displayed a significantly increased gain in skin strength when compared with control animals. These results raise the possibility of efficacy of RGTA OTR4120 in accelerating surgically cutaneous wound healing by enhancing the wound breaking strength and improving the microcirculation.

Regulation of scar formation by vascular endothelial growth factor

Vascular endothelial growth factor (VEGF-A) is known for its effects on endothelial cells and as a positive mediator of angiogenesis. VEGF is thought to promote repair of cutaneous wounds due to its proangiogenic properties, but its ability to regulate other aspects of wound repair, such as the generation of scar tissue, has not been studied well. We examined the role of VEGF in scar tissue production using models of scarless and fibrotic repair. Scarless fetal wounds had lower levels of VEGF and were less vascular than fibrotic fetal wounds, and the scarless phenotype could be converted to a scar-forming phenotype by adding exogenous VEGF. Similarly, neutralization of VEGF reduced vascularity and decreased scar formation in adult wounds. These results show that VEGF levels have a strong influence on scar tissue formation. Our data suggest that VEGF may not simply function as a mediator of wound angiogenesis, but instead may play a more diverse role in the wound repair process.

Development of a method for the evaluation of wound tensile strength in cynomolgus macaques

INTRODUCTION

Numerous in vivo wound healing models have been developed to evaluate the potential of drugs to affect the processes involved in wound healing, including angiogenesis. The majority of these models are frequently conducted in rodents, rabbits, and pigs and are terminal in nature. Due to the species specificity of many biotherapeutic molecules under development a non-terminal model in the cynomolgus monkey was evaluated in this study.

METHODS

To evaluate wound tensile strength, 3 full thickness skin incisions (2 cm long and 3 mm deep) were created on each side of the midline with a micro-fine surgical scalpel. Wounds were closed with SteriStrips applied over Mastisol, and covered with Tegaderm. The animals were then fitted with primate jackets. In Study 1, 3 male macaques per group received daily intramuscular injections of saline or dexamethasone (1 mg/kg) from Day-1 through Day 11. In Study 2, 3 males macaques per treatment group received a single intravenous injection of saline or anti-VEGF mAb (20 mg/kg) on Day-1. In Studies 1 and 2 wounds were created on Day 1. In Study 3, 3 males and 3 female macaques per treatment group received anti-VEGF mAb (20 mg/kg) on Days 1, 8, 15 and 22. In study 3, wounds were created on Day 12. On Days 4, 8, and 11 relative to wound creation, two randomized incisions per animal were evaluated with a Biomechanical Tissue Characterization System.

RESULTS

In Study 1, there was a statistically significant reduction in wound strength in the dexamethasone treated group on Day 11 as compared to saline negative control. There was a statistically significant reduction in wound strength in the anti-VEGF mAb treated animals on Day 8 as compared to saline in Study 2. Statistical evaluation of wound strength between saline treated animals and the anti-VEGF mAb treated animals showed a significant reduction in wound strength in the anti-VEGF mAb treatment group on Day 8 (Fig. 3). In all studies there were open wound sites at the time of evaluation, which ranged from 6 to 50% on Day 4, 3 to 17% on Day 8, and 6% on Day 11.

DISCUSSION

These studies demonstrate a potential method for evaluating the strength of sterile incisional wounds in the cynomolgus monkey, which allows for multiple evaluations of wound strength within an animal over time in a non-terminal model. Dexamethasone and anti-VEGF mAb produced significant reductions in wound healing on Day 11 and 8, respectively. It was inconclusive whether the number of open incisional sites was related to the test article, incomplete closure at the time of surgery, or movement of the animals in the primate jacket.

Mechanisms of adverse effects of anti-VEGF therapy for cancer

Advances in understanding the role of vascular endothelial growth factor (VEGF) in normal physiology are giving insight into the basis of adverse effects attributed to the use of VEGF inhibitors in clinical oncology. These effects are typically downstream consequences of suppression of cellular signalling pathways important in the regulation and maintenance of the microvasculature. Downregulation of these pathways in normal organs can lead to vascular disturbances and even regression of blood vessels, which could be intensified by concurrent pathological conditions. These changes are generally manageable and pose less risk than the tumours being treated, but they highlight the properties shared by tumour vessels and the vasculature of normal organs.

Bevacizumab in the treatment of metastatic colorectal cancer: safety profile and management of adverse events

Bevacizumab is well suited for use in combination with first- or second-line chemotherapy in the treatment of metastatic colorectal cancer because its side effects are predictable and appear not to add to the incidence or severity of the side effects of chemotherapy. Clinical trials of bevacizumab in combination with oxaliplatin-containing and 5-fluorouracil-based regimens have shown that combination therapy is well tolerated and its toxicity is not substantially greater than that of the chemotherapy alone. Preliminary data from community-based and observational studies show that the incidence and severity of adverse events with combinations of bevacizumab and newer chemotherapy regimens are similar to those in the pivotal phase III trial with irinotecan, 5-fluorouracil, and leucovorin plus bevacizumab. Across trials, these side effects include a greater risk of grade 3 hypertension and grade 1 or 2 proteinuria, a slight increase (<2 percentage points) in grade 3 or 4 bleeding, and impaired surgical wound healing in patients who undergo surgery during treatment with bevacizumab. Potentially life-threatening events (arterial thrombotic events and gastrointestinal perforation) have occurred in a small number of patients. Close patient monitoring, especially in patients who are at greater risk of adverse events, is important.

Radiation pneumonitis and fibrosis: Mechanisms underlying its pathogenesis and implications for future research

Radiation pneumonitis and subsequent radiation pulmonary fibrosis are the two main dose-limiting factors when irradiating the thorax that can have severe implications for patients' quality of life. In this article, the current concepts about the pathogenetic mechanisms underlying radiation pneumonitis and fibrosis are presented. The clinical course of fibrosis, a postulated acute inflammatory stage, and a late fibrotic and irreversible stage are discussed. The interplay of cells and the wide variety of molecules orchestrating the immunologic response to radiation, their interactions with specific receptors, and the cascade of events they trigger are elucidated. Finally, the implications of this knowledge with respect to the therapeutic interventions are critically presented.

[(Side) effects of VEGF inhibition]

Vascular endothelial growth factor (VEGF) plays a pivotal role for embryo- and organogenesis. By regulating haemodynamics, (lymphoid) vessel architecture, haematopoiesis and immune system, endocrinology and reparative processes in adults, inhibited VEGF can cause multiple adverse events. Although the intravitreal administration of smaller doses can drastically reduce the systemic exposure, possible local side effects on retinal perfusion and survival of neuronal tissue must be taken into consideration. Before experience has been gained with VEGF inhibitors for longer than several years, individual discussion before the use, extensive informed consent and careful follow-up are necessary. From the ethical point of view, the available drugs should not be used without hesitation despite the clear benefit. First experiences with bevacizumab (Avastin), the first available (off-label) drug in Germany, are reported. In future, direct comparison of the different available drugs has to assess possible differences in the risk-benefit profile.