VEGF Axis Research Articles

CEP-11981, a small molecule inhibitor of multiple angiogenic targets, in a preclinical system of urothelial carcinoma (UC).

293 Background: The systemic therapy of advanced UC has significant unmet needs. Angiogenesis appears to play a major tumorigenic role in UC, and inhibitors of the VEGF axis have demonstrated activity in clinical trials. Ang/Tie2 and FGFR1 are angiogenic pathways that may collaborate with the VEGF pathway to promote growth. Hence, we sought to examine the preclinical activity of CEP-11981, a small molecule inhibitor of Ang/Tie2, FGFR1 and VEGFR-1-2, in UC. Methods: The in vitro anti-tumor activity of CEP-11981 was evaluated in 4 human cell-lines (5637, TCC-SUP, RT4, RT112). In vivo examination of the anti-tumor activity of different doses of daily oral CEP-11981 for up to 4 weeks was examined in subcutaneous RT4 xenografts. Harvested xenograft tumors were subjected to immunohistochemistry (IHC) to evaluate apoptosis (cleaved-caspase [cc]-3) and angiogenesis (CD31). Results: In vitro activity was not detected at low micromolar concentrations in all 4 cell-lines (attainable in human subjects). Preliminary experiments suggested that both 5 mg/kg and 10 mg/kg orally once daily induced similar regressions of RT4 xenografts, which appeared greater than regressions with 2.5 mg/kg orally once daily. Given that the weight of mice was better maintained with 5 mg/kg dose, we performed the confirmatory experiment comparing placebo with CEP-11981 at 5 mg/kg orally once daily in RT4 xenografts. At this dose, CEP-11981 significantly arrested the growth of UC xenografts compared to control (p<0.05). IHC of harvested RT4 xenografts demonstrated numerically lower angiogenesis (p=not statistically significant) but no change in cc-3. Modulation of Tie2 is being examined. Conclusions: CEP-11981 demonstrated significant preclinical cytostatic anti-tumor activity against human UC xenografts in a murine model, which was attributable to inhibition of angiogenesis. Clinical development of CEP-11981 in tolerable combination regimens and the discovery of tumor and host related biomarkers predictive for benefit are warranted.

Phase I Study of Sorafenib and Whole-liver Radiation Therapy (WLRT) or Stereotactic Body Radiation Therapy (SBRT) for Liver Metastases

SBRT has efficacy in selected patients with liver metastases but out-of-field progression is common despite local control. WLRT can palliate symptoms from diffuse liver metastases, but durable responses are rare. Sorafenib is a tyrosine kinase inhibitor that targets a number of kinases involved in angiogenesis including VEGFR-2/3 and PDGF-β. Preclinical data has suggested improved efficacy of RT in combination with VEGF axis inhibition. Thus, a phase I study evaluating sorafenib combined with SBRT and WLRT in patients with liver metastases was conducted. Eligible patients had metastases from solid cancers not suitable for standard local and systemic therapies, Child-Pugh A status, liver enzymes <5x normal, platelets >100,000. RT was delivered in 2 strata: (1) focal SBRT (with doses from 30 to 60 Gy in 6 fractions) and (2) diffuse WLRT (21.6 Gy in 6 fractions). Maximal permitted dose to luminal GI tract was 33 Gy. Sorafenib was dose escalated in each strata from 400 mg (200 mg po bid, level 1) to 600 mg (400 mg po q am and 200 mg po q pm, level 2) to 800 mg (400 mg po bid, level 3) over 4 weeks (pre-, during, and post-RT). Dose limiting toxicity (DLT) was defined as grade 3, 4, or 5 classic or nonclassic radiation induced liver disease (RILD) or any grade 4 or 5 RT-related toxicity. Evaluable patients received at least 75% of the study treatment and were followed for at least 3 months without liver PD. Fifty-three patients consented to participate in this study. Nineteen patients were screened ineligible, and 1 did not initiate therapy, leaving 33 eligible patients who initiated therapy (18 partial liver, 15 whole liver) with the most common diagnoses colon (10) and melanoma (7). In the partial liver SBRT cohort (doses 30 to 54 in 6 fractions, med dose: 42 Gy), no DLT was seen in 15 evaluable patients treated at level 1 (3), level 2 (6), and level 3 (6). One additional patient in level 2 was not evaluable due to discontinuation of sorafenib prior to RT due to sorafenib toxicity. Two other patients (1-level 2, 1-level 3) had sorafenib dose reductions to 200 mg daily due to sorafenib toxicity, without DLT. Three patients developed transient grade 3 chest wall pain (1-level 1, 2-level 2). Median survival was 14.0 months. In the WLRT strata, 2 grade 5 liver DLTs were seen: 1 of 6 evaluable patients at level 1, and 1 of 5 evaluable patients at level 2 (2 patients at 2-month follow-up). One grade 3 pneumonitis (level 2) and 1 chest wall pain (level 2) were also seen. Four additional WLRT patients died of other causes during RT (urosepsis, level 1) and at 3-3.5 months from progressive disease. Median survival of WLRT patients was 5.8 months. Full dose sorafenib can be combined safely with SBRT, although chest wall toxicity is increased. Serious toxicity was seen following low dose sorafenib combined with whole liver RT at 21.6 Gy.

174O - VEGF-a-induced Treg Proliferation, A Novel Mechanism of Tumor Immune Escape in Colorectal Cancer: Effects of Anti-VEGF/VEGFR Therapies

ABSTRACT Background Regulatory T cells (Treg) are suspected of hindering an effective antitumor immune response in cancer. Multi-target anti-angiogenic tyrosine kinase inhibitors (TKI) that are routinely used as first or second line treatment of cancer patients, have been shown to decrease Treg proportion in tumor-bearing mice and metastatic renal cancer patients. However, the role of VEGF/VEGFR blockade in this effect is still debatable, and the direct impact of VEGF-A on Treg has not been studied. Methods Treg proportion, number were analyzed by flow cytometry in peripheral blood of metastatic colorectal cancer (mCRC) patients treated with bevacizumab, and in CT26 tumor-bearing mice treated with drugs targeting the VEGF axis. The direct impact of VEGF on Treg increase in cancer was also studied. Results Sunitinib (a TKI targeting VEGFR, PDGFR, c-kit), and anti-VEGF-A antibody both decreased Treg in CT26 tumor-bearing mice. Masitinib, a TKI that does not target VEGFR, did not reduce Treg proportion in CT26 bearing mice. Bevacizumab, an anti-VEGF-A monoclonal antibody, reduced Treg proportion in peripheral blood of mCRC patients. Proliferation of Treg was enhanced in CT26 tumor-bearing mice compared to tumor-free mice and was decreased after anti-VEGF-A treatment. Furthermore, in vitro experiments have shown that VEGF-A could directly induce Treg proliferation. VEGFR1 and 2 were expressed on Treg in the presence of a tumor. Anti-VEGFR2 antibody administration reduces Treg proportion and also proliferation in CT26 bearing mice, but anti-VEGFR1 antibody did not, suggesting that VEGF-A-induced Treg proliferation was dependent on VEGFR2 expression. In metastatic CRC patients, Treg proliferation was also enhanced compared to healthy volunteers and was blocked by bevacizumab treatment. Conclusions We identified a new mechanism by which VEGF-A induced by the tumor could stimulate Treg proliferation. VEGF-A/VEGFR2 blockade reduced Treg proportion and proliferation in tumor-bearing mice and metastatic CRC patients suggesting that combination of anti-VEGF-A/VEGFR2 therapies with immunotherapeutic approaches in the future might be particularly relevant in CRC patients. Disclosure J. Taieb: advisory role, Roche; research grant, Roche. All other authors have declared no conflicts of interest.

Pazopanib in advanced and platinum-resistant urothelial cancer: an open-label, single group, phase 2 trial

The development of new drugs for patients with refractory urothelial cancer is still an unmet medical need. Preclinical evidence lends support to a rationale for targeting of the VEGF or platelet-derived growth-factor axis. We therefore investigated the activity and safety of pazopanib, a multitarget drug with antiangiogenic activity, in patients with urothelial cancer. In an open-label, single-group, phase 2 study, patients (aged ≥18 years) with relapsed or refractory urothelial cancer were given pazopanib 800 mg per day, orally. They were treated until disease progression or prohibitive toxicity occurred. The primary endpoint was the proportion of patients who achieved a confirmed objective response, defined as complete or partial response, after independent review, and was analysed by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT01031875. The trial has been completed. 21 (51%) of 41 patients enrolled were given pazopanib as third-line or further-line treatment. 26 (63%) patients had an Eastern Cooperative Oncology Group performance status of 1 or 2. Seven patients had a confirmed objective response (17·1%, 95% CI 7·2-32·1), all of which were partial responses. The most frequent treatment-related grade 3 adverse events were hypertension (three [7%]), fatigue (two [5%]), and gastrointestinal and vaginal fistulisations (two each [5%]). One patient died as a result of duodenal fistulisation that was related to tissue response of bulky tumour masses. Pazopanib has single-agent activity in patients with heavily pretreated metastatic urothelial cancer, and warrants further study in this setting. Particular attention should be paid to patients with bulky tumour masses adjacent to viscera because fistulisation is probably related to the response to pazopanib and is the most frequent serious adverse event. Fondazione IRCCS Istituto Nazionale dei Tumori provided the grant. GlaxoSmithKline provided the study drug and provided funding for the independent radiological review.

Second-line treatment for renal cell cancer

Second-line treatment for renal cell cancer

SWOG 0514: a phase II study of sorafenib in patients with unresectable or metastatic gallbladder carcinoma and cholangiocarcinoma

Gallbladder and cholangiocarcinomas represent a heterogeneous group of malignant diseases that commonly present at an advanced stage and have limited therapeutic options. Based on the role of the Ras-Raf-Mek-Erk pathway and the VEGF axis in biliary carcinomas, we conducted a phase II study of sorafenib in patients with advanced biliary cancers. Eligible patients had no prior therapy for metastatic or unresectable disease. Sorafenib was administered at 400 mg po twice daily continuously. The study was terminated after the first stage of accrual due to failure to meet the primary objective. A confirmed response rate of 0% (0%-11%) was observed. Thirty-nine percent of patients demonstrated stable disease (including 2 with unconfirmed PR). PFS was 3 months (95% CI: 2-4 months) and OS 9 months (95% CI: 4-12 months). The most common grade 3 and 4 toxicities included hand-foot skin reaction (13%), bilirubin elevation (13%), venous thromboembolism (10%), AST/ALT elevation (10%) and elevated alkaline phosphatase (10%). While treatment with sorafenib did not result in objective responses, patients with biliary cancers receiving this drug had some therapeutic benefit. Additional studies with sorafenib in combination with chemotherapy or other targeted agents may be warranted.

AMG 386: profile of a novel angiopoietin antagonist in patients with ovarian cancer

Introduction: Ovarian cancer is the second most common gynecologic malignancy in the world with the majority of women presenting with advanced disease; whilst chemotherapeutic advances have improved progression-free survival, the increases in overall survival have been marginal. Novel biologic agents, including those designed to disrupt tumor angiogenesis, have demonstrated promising antitumor activity.Areas covered: This review evaluates AMG 386, a novel investigational angiopoietin antagonist peptide-Fc fusion protein (peptibody), which potently and selectively inhibits angiopoietin-1 and angiopoietin-2 binding to the Tie2 tyrosine kinase receptor. Preclinical and clinical studies for AMG 386 are summarized, highlighting data pertaining to ovarian cancer. The role of angiopoietins in regulating physiologic and tumorigenic angiogenesis is addressed, as well as a brief discussion of non-angiopoietin anti-angiogenic strategies, followed by a review of preclinical, Phase I and II data and ongoing clinical studies for AMG 386, all in the context of ovarian cancer.Expert opinion: AMG 386 has clinical activity and an acceptable safety profile both as monotherapy and in combination with chemotherapy. Of note, as the toxicity profiles of AMG 386 and inhibitors of the VEGF axis do not substantially overlap, AMG 386 could potentially be combined with other anti-angiogenic compounds to maximize disruption of malignant vascularization in ovarian cancer and other solid tumors.

Bisphosphonates suppress insulin‐like growth factor 1‐induced angiogenesis via the HIF‐1α/VEGF signaling pathways in human breast cancer cells

Adjunctive chemotherapy with bisphosphonates has been reported to delay bone metastasis and improve overall survival in breast cancer. Aside from its antiresorptive effect, bisphosphonates exhibit antitumor activities, in vitro and in vivo, via several mechanisms, including antiangiogenesis. In this study, we investigated the potential molecular mechanisms underlying the antiangiogenic effect of non-nitrogen-containing and nitrogen-containing bisphosphonates, clodronate and pamidronate, respectively, in insulin-like growth factor (IGF)-1 responsive human breast cancer cells. We tested whether bisphosphonates had any effects on hypoxia-inducible factor (HIF)-1alpha/vascular endothelial growth factor (VEGF) axis that plays a pivotal role in tumor angiogenesis, and our results showed that both pamidronate and clodronate significantly suppressed IGF-1-induced HIF-1alpha protein accumulation and VEGF expression in MCF-7 cells. Mechanistically, we found that either pamidronate or clodronate did not affect mRNA expression of HIF-1alpha, but they apparently promoted the degradation of IGF-1-induced HIF-1alpha protein. Meanwhile, we found that the presence of pamidronate and clodronate led to a dose-dependent decease in the newly-synthesized HIF-1alpha protein induced by IGF-1 in breast cancer cells after proteasomal inhibition, thus, indirectly reflecting the inhibition of protein synthesis. In addition, our results indicated that the inhibitory effects of bisphosphonates on the HIF-1alpha/VEGF axis are associated with the inhibition of the phosphoinositide 3-kinase/AKT/mammalian target of rapamycin signaling pathways. Consistently, we demonstrated that pamidronate and clodronate functionally abrogated both in vitro and in vivo tumor angiogenesis induced by IGF-1-stimulated MCF-7 cells. These findings have highlighted an important mechanism of the pharmacological action of bisphosphonates in the inhibition of tumor angiogenesis in breast cancer cells.

Targeting angiogenesis in hepatocellular carcinoma: focus on VEGF and bevacizumab

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and one of the few malignancies with an increasing incidence in the USA. While the relationship between HCC and its inciting risk factors (e.g., hepatitis B, hepatitis C and alcohol liver disease) is well defined, driving genetic alterations are still yet to be identified. Clinically, HCC tends to be hypervascular and, for that reason, transarterial chemoembolization has proven to be effective in managing many patients with localized disease. More recently, angiogenesis has been targeted effectively with pharmacologic strategies, including monoclonal antibodies against VEGF and the VEGF receptor, as well as small-molecule kinase inhibitors of the VEGF receptor. Targeting angiogenesis with these approaches has been validated in several different solid tumors since the initial approval of bevacizumab for advanced colon cancer in 2004. In HCC, only sorafenib has been shown to extend survival in patients with advanced HCC and has opened the door for other anti-angiogenic strategies. Here, we will review the data supporting the targeting of the VEGF axis in HCC and the preclinical and early clinical development of bevacizumab.

IL-1β Regulates Blood-Brain Barrier Permeability via Reactivation of the Hypoxia-Angiogenesis Program

Loss of blood-brain barrier (BBB) integrity is believed to be an early and significant event in lesion pathogenesis in the inflammatory demyelinating disease multiple sclerosis (MS), and understanding mechanisms involved may lead to novel therapeutic avenues for this disorder. Well-differentiated endothelium forms the basis of the BBB, while astrocytes control the balance between barrier stability and permeability via production of factors that restrict or promote vessel plasticity. In this study, we report that the proinflammatory cytokine IL-1beta, which is prominently expressed in active MS lesions, causes a shift in the expression of these factors to favor plasticity and permeability. The transcription factor, hypoxia inducible factor-1 (HIF-1), plays a significant role in this switch. Using a microarray-based approach, we found that in human astrocytes, IL-1beta induced the expression of genes favoring vessel plasticity, including HIF-1alpha and its target, vascular endothelial growth factor-A (VEGF-A). Demonstrating relevance to MS, we showed that HIF-1alpha and VEGF-A were expressed by reactive astrocytes in active MS lesions, while the VEGF receptor VEGFR2/flk-1 localized to endothelium and IL-1 to microglia/macrophages. Suggesting functional significance, we found that expression of IL-1beta in the brain induced astrocytic expression of HIF-1alpha, VEGF-A, and BBB permeability. In addition, we confirmed VEGF-A to be a potent inducer of BBB permeability and angiogenesis, and demonstrated the importance of IL-1beta-induced HIF-1alpha in its regulation. These results suggest that IL-1beta contributes to BBB permeability in MS via reactivation of the HIF-VEGF axis. This pathway may represent a potential therapeutic target to restrict lesion formation.