Overcoming resistance to antiangiogenic therapies

Medicinal attributes of thienopyrimidine scaffolds incorporating the aryl urea motif as potential anticancer candidates via VEGFR inhibition

Worldwide, cancer is a major public health concern. It is a well-acknowledged life-threatening disease. Despite numerous advances in the understanding of the genetic basis of cancer growth and progression, therapeutic challenges remain high. Human tumors exhibited mutation or overexpression of several tyrosine kinases (TK). The vascular endothelial growth factor receptor (VEGFR) is a TK family member and is well known for tumor growth and progression. Therefore, VEGF/VEGFR pathway inhibition is an appealing approach for cancer drug discovery. This review will discuss the structure-based optimization of thienopyrimidines incorporating the aryl urea moiety to develop scaffolds of potent anticancer activity via VEGFR inhibition published between 2013 and 2023. Increasing knowledge of probable scaffolds that can act as VEGFR inhibitors might spur the hunt for novel anticancer medications that are safer, more effective, or both.

Prospective validation of VEGF and eNOS polymorphisms as predictors of first-line bevacizumab efficacy in patients with metastatic colorectal cancer

Bevacizumab (Bev) plus chemotherapy is a standard first-line treatment in metastatic colorectal cancer (mCRC), however to date no predictive factors of response have been identified. Results of our previous analysis on patients enrolled in a randomized prospective phase III multicenter study (ITACa study) showed a predictive value of Vascular Endothelial Growth Factor (VEGF) polymorphism (VEGF + 936), a 27-nucleotide variable number tandem repeat (VNTR) of the endothelial nitric oxide synthase (eNOS) gene and eNOS + 894 polymorphism. mCRC patients, treated with Bev plus chemotherapy, were included in this prospective validation trial. eNOS + 894G > T was analyzed by Real time PCR, while the eNOS VNTR and VEGF + 936C > T were determined by standard PCR and direct sequencing analysis. These polymorphisms were assessed in relation to progression-free survival (PFS), overall survival (OS) and objective response rate (ORR). These three polymorphisms were not predictive of PFS (p 0.91, 0.59 and 0.09, respectively), and OS (p 0.95, 0.32 and 0.46, respectively). Moreover, the haplotype analyses did not confirm what was found in our previous study; patients bearing a specific haplotype of eNOS had not significantly improved outcomes. This prospective study failed to validate the predictive impact of eNOS and VEGF polymorphisms for response to Bev plus first-line chemotherapy in mCRC patients.

FOLFOXIRI Resistance Induction and Characterization in Human Colorectal Cancer Cells

FOLFOXIRI, i.e., the combination of folinic acid, 5-fluorouracil, oxaliplatin, and irinotecan, is a first-line treatment for colorectal carcinoma (CRC), yet non-personalized and aggressive. In this study, to mimic the clinical situation of patients diagnosed with advanced CRC and exposed to a chronic treatment with FOLFOXIRI, we have generated the CRC cell clones chronically treated with FOLFOXIRI. A significant loss in sensitivity to FOLFOXIRI was obtained in all four cell lines, compared to their treatment-naïve calls, as shown in 2D cultures and heterotypic 3D co-cultures. Acquired drug resistance induction was observed through morphometric changes in terms of the organization of the actin filament. Bulk RNA sequencing revealed important upregulation of glucose transporter family 5 (GLUT5) in SW620 resistant cell line, while in the LS174T-resistant cell line, a significant downregulation of protein tyrosine phosphatase receptor S (PTPRS) and oxoglutarate dehydrogenase-like gene (OGDHL). This acquired resistance to FOLFOXIRI was overcome with optimized low-dose synergistic drug combinations (ODCs) acting via the Ras-Raf-MEK-ERK pathway. The ODCs inhibited the cell metabolic activity in SW620 and LS174T 3Dcc, respectively by up to 82%.

Bevacizumab is an effective treatment for symptomatic cerebral necrosis after carbon ion therapy for recurrent intracranial malignant tumours: A case report

Carbon ion therapy (CIT) is a form of particle therapy, which not only spares normal tissues but may also improve local control of recurrent intracranial tumours. Cerebral radiation necrosis (RN) is one of the most serious adverse reactions of recurrent brain tumours following reirradiation, which may lead to neurological decline or even death. Bevacizumab is an anti-vascular endothelial growth factor antibody, which has been used to treat symptomatic RN. However, studies on bevacizumab for the treatment of CIT-induced RN are sparse. The present study described two cases that were successfully treated with bevacizumab for symptomatic RN following CIT for recurrent intracranial malignant tumours. The two recurrent intracranial malignant tumours, a chondrosarcoma in the right cavernous sinus and an anaplastic meningioma in the right frontal lobe, were enrolled in a clinical trial of CIT. Both cases were treated intravenously with bevacizumab when deterioration that appeared to be symptomatic brain RN was observed. Just before CIT, enhanced magnetic resonance imaging (MRI) was performed in each case to confirm tumour recurrence. Both cases exhibited a deterioration in symptoms, as well as on MRI, at 12-month intervals following CIT. The first case underwent positron emission tomography/computed tomography to confirm no increase in fluorodeoxyglucose uptake in lesion areas. Both cases were diagnosed as having symptomatic brain RN and began intravenous administration of four cycles of 5 mg/kg bevacizumab biweekly. The patients responded well, with rapid and marked improvements on MRI, and in clinical symptoms. No tumour progression was observed 24 months after CIT. In conclusion, bevacizumab was revealed to exert marked effects on symptomatic brain RN following CIT. Notably, cycles of bevacizumab should be administered specifically based on the aim of treating brain necrosis, and long-term or prophylactic applications are not recommended.

Proteomic investigations into resistance in colorectal cancer

Introduction: Despite advances in screening and treatment options, colorectal cancer (CRC) remains one of the most prevalent and lethal cancer subtypes. Resistance to cytotoxic or targeted therapy has remained a constant challenge to the treatment and long-term management of patients, attracting intense worldwide investigation since the 1950s. Through extensive investigations into the proteomic mechanisms and functions that convey resistance to therapy/s, researchers have become able to implicate alterations in several signaling pathways that provide and sustain resistance to treatment.Areas covered: In this review, we summarize how protein alterations are associated with resistance to therapy, with particular emphasis on CRC. An overview of the mechanisms of therapeutic resistance is described, highlighting recent studies which endeavor to elucidate the proteomic changes that are associated with the acquisition and promulgation of therapeutic resistance.Expert opinion: While cancers such as CRC have been intensively studied for decades, unresponsiveness and the resistance to therapy remain critical obstacles in the treatment of patients. Due to the inherent biological and clinical heterogeneity of individual CRCs, proteomic methods stand to become powerful tools to provide biological insights that may guide therapeutic strategies with the ultimate goal of refining emergent immunotherapeutic treatments.

[Study on colorectal cancer using air-liquid interface organoid culture method]

Colorectal cancer is a disease with high unmet medical needs. An increase in the number of cancer patients who are resistant to anti-cancer drugs is one of factors that increase the number of fatalities. Since there was no suitable experimental model to recapitulate the tumor environment in which various cells in the tissues exist, it was extremely difficult to develop a medicine that overcomes the anti-cancer drug resistance in each colorectal cancer patient. In this review, we describe the current status and problems of drug therapy for colorectal cancer patients, and introduce our study to develop the new targeting drugs using human colon tissue-derived air liquid interface organoid culture method.

The Intersection between Tumor Angiogenesis and Immune Suppression

Both immune checkpoint inhibitors (ICI) and antiangiogenesis agents have changed the landscape of cancer treatment in the modern era. While antiangiogenesis agents have demonstrated activities in tumors with high vascularization, including renal cell carcinoma and colorectal cancer, the effect of ICIs has been seen mainly in immunologically recognized tumors, with highly immune-infiltrative lymphocytes. The main challenge in the drug development of ICIs is moving their activities to noninflamed tumors and overcoming resistance that is driven, in part, by the immune-suppressive microenvironment. Angiogenesis factors drive immune suppression by directly suppressing the antigen-presenting cells as well as immune effector cells or through augmenting the effect of regulatory T cells (Treg), myeloid-derived suppressor cells (MDSC), and tumor-associated macrophages (TAM). Those suppressive immune cells can also drive angiogenesis, creating a vicious cycle of impaired immune activation. The combination of bevacizumab and ipilimumab was the first to show the promising effect of antiangiogenesis and ICIs. A plethora of similar combinations has entered the clinic since then, confirming the promising effects of such approach.

Bevacizumab treatment for radiation brain necrosis: mechanism, efficacy and issues

Vascular damage is followed by vascular endothelial growth factor (VEGF) expression at high levels, which is an important mechanism forradiation brain necrosis development. Bevacizumab alleviates brain edema symptoms caused by radiation brain necrosis through inhibiting VEGF and acting on vascular tissue around the brain necrosis area. Many studies have confirmed that bevacizumab effectively relieves symptoms caused by brain necrosis, improves patients' Karnofsky performance status (KPS) scores and brain necrosis imaging. However, necrosis is irreversible, and hypoxia and ischemia localized in the brain necrosis area may easily lead to radiation brain necrosis recurrence after bevacizumab is discontinued. Further studies are necessary to investigate brain necrosis diagnoses, bevacizumab indications, and the optimal mode of administration, bevacizumab resistance and necrosis with a residual or recurrent tumor.

Recruited bone marrow derived cells, local stromal cells and IL-17 at the front line of resistance development to anti-VEGF targeted therapies

Although anti-angiogenic agents targeting VEGF have shown affordable beneficial outcomes in several human cancer types, in most pre-clinical and clinical studies, these effects are transient and followed by rapid relapse and tumor regrowth. Recently, it has been suggested that recruited bone marrow derived cells (BMDCs) to the tumor-microenvironment together with stromal cells play an important role in development of resistance to anti-VEGF therapies. Additionally, acquired resistance to anti-VEGF therapies has shown to be mediated partly through overexpression of different pro-angiogenic cytokines and growth factors including G-CSF, IL-6, IL-8, VEGF and FGF by these cells. Alongside, IL-17, a pro-inflammatory cytokine, mostly secreted by infiltrated CD4⁺ T helper cells, has shown to mediate resistance to anti-VEGF therapies, through recruiting BMDCs and modulating stromal cells activities including endothelial cells, tumor associated macrophages and cancer associated fibroblasts. Here, we examined the role of BMDCs, tumor stromal cells, IL-17 and their negotiation in development of resistance to anti-VEGF targeted therapies.

RGS5 decreases the proliferation of human ovarian carcinoma‑derived primary endothelial cells through the MAPK/ERK signaling pathway in hypoxia

Regulator of G-protein signaling 5 (RGS5), a tissue-specific signal-regulating molecule, plays a key role in the development of the vasculature. It was recently found that RGS5 is abundantly expressed in epithelial ovarian cancer (EOC) compared with the normal ovaries. However, the distribution of RGS5 in EOC and its significance require further investigation. The aim of the present study was to investigate the expression of RGS5 in EOC, as well as its association with cancer differentiation, metastasis and clinicopathological parameters. Immunohistochemistry (IHC), western blotting, RT-PCR, wound-healing, cell proliferation and flow cytometric assays were the methods used in the present study. RGS5 was highly expressed in the cytoplasm of ovarian carcinoma cells and in microvascular structures. The expression of RGS5 in EOC was negatively associated with peritoneal metastasis (P=0.004), but it was not found to be associated with age, tumor size, clinical stage or lymph node metastasis (P>0.05). EOC patients with high RGS5 expression had a prolonged progression-free survival (72.34±8.41 vs. 43.56±5.41 months, P<0.001). High expression of RGS5 was correlated with significantly lower microvascular density (MVD) as indicated by the expression of CD34, whereas the opposite was observed in tissues with low RGS5 expression (P<0.05). Hypoxia increased RGS5 expression in ovarian carcinoma-derived endothelial cells (ODMECs), whereas the proliferative capacity of ODMECs exhibited a significant increase following RNAi-mediated reduction of RGS5 expression. These data indicated that RGS5 plays a key role in angiogenesis in ovarian carcinoma. In addition, RGS5 downregulated the expression of the downstream proteins CDC25A, CDK2 and cyclin E, which are mediated by the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway, causing ODMEC arrest in the G1 phase of the cell cycle under hypoxic conditions. Collectively, our data indicated that RGS5 is crucial for the occurrence and development of ovarian cancer, and that RGS5 and its signaling pathway may serve as anti-angiogenesis targets for the treatment of ovarian cancer.

Impaired tumor growth and angiogenesis in mice heterozygous for Vegfr2 (Flk1)

VEGF signaling through its tyrosine kinase receptor, VEGFR2 (FLK1), is critical for tumor angiogenesis. Previous studies have identified a critical gene dosage effect of VegfA in embryonic development and vessel homeostasis, neovascularization, and tumor growth, and potent inhibitors of VEGFR2 have been used to treat a variety of cancers. Inhibition of FGFR signaling has also been considered as an antiangiogenic approach to treat a variety of cancers. Inhibition of VEGFR2 with neutralizing antibodies or with pharmacological inhibitors of the VEGFR tyrosine kinase domain has at least short-term efficacy with some cancers; however, also affects vessel homeostasis, leading to adverse complications. We investigate gene dosage effects of Vegfr2, Fgfr1, and Fgfr2 in three independent mouse models of tumorigenesis: two-stage skin chemical carcinogenesis, and sub-cutaneous transplantation of B16F0 melanoma and Lewis Lung Carcinoma (LLC). Mice heterozygous for Vegfr2 display profound defects in supporting tumor growth and angiogenesis. Unexpectedly, additional deletion of endothelial Fgfr1 and Fgfr2 in Vegfr2 heterozygous mice shows similar tumor growth and angiogenesis as the Vegfr2 heterozygous mice. Notably, hematopoietic deletion of two alleles of Vegfr2 had minimal impact on tumor growth, with little effect on angiogenesis, reinforcing the importance of endothelial Vegfr2 heterozygosity. These studies reveal previously unrecognized Vegfr2 gene dosage effects in tumor angiogenesis and a lack of synergy between VEGFR2 and endothelial FGFR1/2 signaling during tumor growth.

Development of an Experimental Model for Analyzing Drug Resistance in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common cancers, for which combination treatment of chemotherapy is employed. However, most patients develop drug resistance during the course of treatment. To clarify the mechanisms of drug resistance, various research models have been developed. Recently, we established a human CRC patients-derived three-dimensional (3D) culture system using an air-liquid interface organoid method. It contained numerous cancer stem cells and showed resistance to 5-fluorouracil and Irinotecan. In this review, we introduce conventional and our established models for studying drug resistance in CRC.

Rechallenge of oxaliplatin-containing regimens in the third- or later-line therapy for patients with heavily treated metastatic colorectal cancer

Purpose

The third- or later-line therapy available often yield poor survival benefit in patients metastatic colorectal cancer (mCRC). The retrospective study aimed to evaluate efficacy of rechallenge of oxaliplatin-containing regimens.

Patients and methods

Patients with mCRC who progressed from fluoropyrimidine, oxaliplatin, and irinotecan in the first- and second-line chemotherapy, were treated by reexposure to oxaliplatin-containing regimen. Patients treated by anti-epidermal growth factor receptor (EGFR) antibodies with irinotecan were included in the control arm.

Results

Ninety-five and 29 patients were treated with either oxaliplatin reexposure or anti-EGFR antibodies with irinotecan, respectively, as the third- or later-line therapy. The median time to treatment failure (TTF) and overall survival (OS) was 3.77 and 12.17 months in the oxaliplatin arm, with 4.77 months of TTF and 11.37 months of OS in the control arm; there was no significance between the 2 arms (p>0.05). Oxaliplatin reexposure resulted in 6.3% objective response rate with no complete response, 6 partial response, 39 stable disease, and 37 progressive disease. The disease control rate was 47.4% (45/95). The multivariate analysis found that patients who achieved disease control by oxaliplatin reexposure had a superior TTF (6.13 vs 1.7 months, p<0.001) and OS (15.73 vs 6.27 months, p<0.001) compared with those presenting with progressive disease.

Conclusion

This study showed that rechallenge of oxaliplatin-containing chemotherapy in the third- or later-line therapy may lead to tumor control and improved survival in mCRC patients, which was equivalent to that of anti-EGFR antibodies with irinotecan.

Clinical significance

Rechallenge of oxaliplatin-containing regimens in the third- or later-line of therapy is a common practice, despite few evidence available. The present study found that rechallenge of oxaliplatin-containing regimens produced equivalent tumor control and survival benefit to that of anti-EGFR antibodies with irinotecan in mCRC.

Biomarkers of evasive resistance predict disease progression in cancer patients treated with antiangiogenic therapies

Numerous antiangiogenic agents are approved for the treatment of oncological diseases. However, almost all patients develop evasive resistance mechanisms against antiangiogenic therapies. Currently no predictive biomarker for therapy resistance or response has been established. Therefore, the aim of our study was to identify biomarkers predicting the development of therapy resistance in patients with hepatocellular cancer (n = 11), renal cell cancer (n = 7) and non-small cell lung cancer (n = 2). Thereby we measured levels of angiogenic growth factors, tumor perfusion, circulating endothelial cells (CEC), circulating endothelial progenitor cells (CEP) and tumor endothelial markers (TEM) in patients during the course of therapy with antiangiogenic agents, and correlated them with the time to antiangiogenic progression (aTTP). Importantly, at disease progression, we observed an increase of proangiogenic factors, upregulation of CEC/CEP levels and downregulation of TEMs, such as Robo4 and endothelial cell-specific chemotaxis regulator (ECSCR), reflecting the formation of torturous tumor vessels. Increased TEM expression levels tended to correlate with prolonged aTTP (ECSCR high = 275 days vs. ECSCR low = 92.5 days; p = 0.07 and for Robo4 high = 387 days vs. Robo4 low = 90.0 days; p = 0.08). This indicates that loss of vascular stabilization factors aggravates the development of antiangiogenic resistance. Thus, our observations confirm that CEP/CEC populations, proangiogenic cytokines and TEMs contribute to evasive resistance in antiangiogenic treated patients. Higher TEM expression during disease progression may have clinical and pathophysiological implications, however, validation of our results is warranted for further biomarker development.

Model driven optimization of antiangiogenics + cytotoxics combination: application to breast cancer mice treated with bevacizumab + paclitaxel doublet leads to reduced tumor growth and fewer metastasis

Bevacizumab is the first-in-class antiangiogenic drug and is almost always administrated in combination with cytotoxics. Reports have shown that bevacizumab could induce a transient phase of vascular normalization, thus ensuring a better drug delivery when cytotoxics administration is adjuvant. However, determining the best sequence remains challenging. We have developed a mathematical model describing the impact of antiangiogenics on tumor vasculature. A 3.4 days gap between bevacizumab and paclitaxel was first proposed by our model. To test its relevance, 84 mice were orthotopically xenografted with human MDA-231^Luc+ refractory breast cancer cells. Two sets of experiments were performed, based upon different bevacizumab dosing (10 or 20 mg/kg) and inter-cycle intervals (7 or 10 days), comprising several combinations with paclitaxel. Results showed that scheduling bevacizumab 3 days before paclitaxel improved antitumor efficacy (48% reduction in tumor size compared with concomitant dosing, p < 0.05) and reduced metastatic spreading. Additionally, bevacizumab alone could lead to more aggressive metastatic disease with shorter survival in animals. Our model was able to fit the experimental data and provided insights on the underlying dynamics of the vasculature's ability to deliver the cytotoxic agent. Final simulations suggested a new, data-informed optimal gap of 2.2 days. Our experimental data suggest that current concomitant dosing between bevacizumab and paclitaxel could be a sub-optimal strategy at bedside. In addition, this proof of concept study suggests that mathematical modelling could help to identify the optimal interval among a variety of possible alternate treatment modalities, thus refining the way experimental or clinical studies are conducted.

Bevacizumab Induces Acute Hypoxia and Cancer Progression in Patients with Refractory Breast Cancer: Multimodal Functional Imaging and Multiplex Cytokine Analysis

Purpose: Bevacizumab, an antibody against endothelial growth factor, is a key but controversial drug in the treatment of metastatic breast cancer. We, therefore, aimed to determine the intrinsic resistance to bevacizumab at the physiologic and molecular levels in advanced breast cancer using PET, dynamic contrast-enhanced MRI, diffuse optical spectroscopic imaging (DOSI), and multiplex cytokine assays.Experimental Design: In total, 28 patients diagnosed with advanced stage III/IV breast cancer receiving single-agent bevacizumab for 1 week followed by paclitaxel combined with bevacizumab underwent ¹⁸F-fluorodeoxyglucose (FDG)-PET, ¹⁸F-fluoromisonidazole (FMISO)-PET, and MRI at both baseline and two courses after treatment initiation. Hemodynamic measurement using DOSI and blood sample collection were performed at baseline and multiple times during the first week after the initiation of single-agent bevacizumab. We distinguished nonresponders from responders by serial FDG-PET based on their glycolytic changes to chemotherapy.Results: Nonresponders showed significantly higher hypoxic activity on FMISO-PET and less tumor shrinkage than responders. Hemodynamic parameters showed higher tumor blood volume and a remarkable decrease in the tissue oxygen level in nonresponders compared with responders after the infusion of single-agent bevacizumab. Multiplex cytokine assays revealed increased plasma levels of both proangiogenic and hypoxia-related inflammatory cytokines in nonresponders and decreased levels in responders.Conclusions: Nonresponders exhibited a higher degree of angiogenesis with more severe hypoxia than responders during bevacizumab treatment. These findings demonstrated that the addition of bevacizumab to paclitaxel treatment under hypoxic conditions could be ineffective and may result in acute hypoxia and increased cytokine secretion associated with cancer progression. Clin Cancer Res; 23(19); 5769-78. ©2017 AACR.

Recruitment of CD11b+Ly6C+ monocytes in non-small cell lung cancer xenografts challenged by anti-VEGF antibody

A series of antibodies against vascular endothelial growth factor (VEGF) have been developed for the treatment of various types of cancer, including non-small cell lung cancer (NSCLC) in recent years. However, tumors frequently demonstrate resistance to these strategies of VEGF inhibition. Efforts to better understand the mechanism underlying the acquired resistance to anti-VEGF antibodies are warranted. In the present study, in order to develop a xenograft model of acquired resistance to anti-VEGF antibody, xenografts of human adenocarcinoma A549 cells were generated through the successive inoculation of tumor tissue explants into first (F1), second (F2) and third (F3) generations of mice treated with the anti-VEGF antibody B20. Tumor growth rate and vessel-forming ability, assessed via cluster of differentiation (CD) 31 staining, were significantly lower in the F1, F2 and F3 groups compared with in the F0 control group (P<0.01), suggesting that drug resistance was not successfully acquired. The percentages of CD11b⁺ myeloid-derived suppressor cells and lymphocyte antigen 6C (Ly6C)⁺ subsets were significantly smaller in F1, F2 and F3 groups compared with in F0 (P<0.01). However, the ratio of Ly6C⁺ to CD11b⁺ cells was significantly higher in the F3 group compared with in F0 and F1 groups (P<0.01), indicating increasing recruitment of the Ly6C⁺ subset with successive challenges with the anti-VEGF antibody. In conclusion, the recruitment of CD11b⁺Ly6C⁺ monocytes increased with successive generations of NSCLC-xenografted mice challenged by B20, an anti-VEGF agent.

REOX: Evaluation of the Efficacy of Retreatment With an Oxaliplatin-containing Regimen in Metastatic Colorectal Cancer: A Retrospective Single-center Study

BACKGROUND

Treatment of metastatic colorectal adenocarcinoma (mCRC) has evolved, and survival is over 30 months in contemporary trials. Nevertheless, there is a paucity of effective regimes after the first or second-line treatment. Thus, reexposure to previously used drugs has become a treatment strategy for some patients. We aimed to evaluate the efficacy of retreatment with an oxaliplatin-containing regimen in mCRC and correlate this with clinicopathologic features.

PATIENTS AND METHODS

We retrospectively analyzed 83 patients with mCRC who underwent reexposure to oxaliplatin (REOX). REOX was defined as a second trial of an oxaliplatin-containing regimen after a previous failure. Primary endpoint was time to treatment failure (TTF).

RESULTS

The median age was 53.5 years, and the female/male ratio was 51.8%/48.2%. The site of the primary tumor was colon (67.5%) and rectal (32.5%). KRAS was mutated in 39.8%. Liver-limited metastasis was found in 19.3% of patients. The main regimen was 5-fluorouracil, levoleucovorin, and oxaliplatin (mFOLFOX6) (84.3%). Bevacizumab and cetuximab were used in 42.2% and 6% of patients, respectively. REOX was used in the third and fourth lines in 48.2% and 25.3% of patients, respectively. The median TTF after REOX was 6.04 months. Overall survival (OS) was 10.04 months. Disease control (complete response + partial response + stable disease) was observed in 56.6%, whereas 42.2% had progressive disease. Partial response + complete response to previous oxaliplatin was predictive of prolonged OS. Patients who attained disease control had better median OS compared with those with progressive disease (14.5 vs. 6.24 months; P < .0001).

CONCLUSION

In the setting of heavily pretreated patients with mCRC, REOX was an effective treatment, with mTTF of 6.04 months in our cohort. Selection of patients with the longest time since previous oxaliplatin can translate in better outcome. Further studies should be conducted to confirm our data.

Pharmacologic resistance in colorectal cancer: a review

Colorectal cancer (CRC) persists as one of the most prevalent and deadly tumor types in both men and women worldwide. This is in spite of widespread, effective measures of preventive screening, and also major advances in treatment options. Despite advances in cytotoxic and targeted therapy, resistance to chemotherapy remains one of the greatest challenges in long-term management of incurable metastatic disease and eventually contributes to death as tumors accumulate means of evading treatment. We performed a comprehensive literature search on the data available through PubMed, Medline, Scopus, and the ASCO Annual Symposium abstracts through June 2015 for the purpose of this review. We discuss the current state of knowledge of clinically relevant mechanisms of resistance to cytotoxic and targeted therapies now in use for the treatment of CRC.

Inhibition of the angiopoietin/Tie2 axis induces immunogenic modulation, which sensitizes human tumor cells to immune attack

BACKGROUND

The angiopoietin/Tie2 pathway is an attractive target for cancer therapy due to its well-known role in regulating angiogenesis. Trebananib, a recombinant peptide-Fc fusion protein, or peptibody, that binds to angiopoietin-1 (Ang1) and Ang2 to block their interaction with the Tie2 receptor, is under active clinical investigation. We investigated whether suppressing the angiopoietin/Tie2 pathway, using the preclinical version of Trebananib (mL4-3 and L1-7(N)), could increase the sensitivity of human tumor cells to immune-mediated lysis through immunogenic modulation, which would make Trebananib a promising candidate for combination with immunotherapy.

METHODS

We assessed human carcinoma cells for expression and activation of Ang1 and Ang2 and their receptor tyrosine kinase Tie2. In vitro, we exposed tumor cell lines expressing Tie2 to the peptibodies mL4-3 and L1-7(N), which inhibit the binding of Ang1 and Ang2 to Tie2, and assessed the cells for changes in viability, proliferation, surface phenotype, and sensitivity to attack by antigen-specific cytotoxic T lymphocytes (CTLs).

RESULTS

Suppression of the angiopoietin/Tie2 pathway using mL4-3 and L1-7(N) had no effect on the proliferation or viability of tumor cells. However, these inhibitors markedly altered tumor cell phenotype, rendering tumor cells significantly more sensitive to antigen-specific CTL killing. ICAM-1 was shown to be mechanistically involved in these inhibitors' ability to sensitize tumor cells to immune-mediated attack by functional blocking studies.

CONCLUSION

Our findings provide a rationale for the combination of agents targeting the angiopoietin/Tie2 pathway with cancer immunotherapies.

Use of VEGFR-2 targeted ultrasound contrast agent for the early evaluation of response to sorafenib in a mouse model of hepatocellular carcinoma

PURPOSE

The aim of this study was to assess the early response to sorafenib using ultrasound molecular imaging in a murine model of hepatocellular carcinoma (HCC).

PROCEDURES

A xenograft model of HCC was established. Then, mice were divided in two groups and received treatment (sorafenib) or placebo for 14 days. The treatment group was further divided into non-responders and responders according to the degree of growth. Contrast enhanced ultrasound (CEUS) was performed using VEGFR-2 targeted microbubbles (BR55, Bracco Suisse SA, Geneva, Switzerland). Dedicated software was used to quantify the amount of bound microbubbles in the tumor as a numerical value (differential targeted enhancement (dTE)). Tumors were then excised and western blot analysis performed.

RESULTS

The dTE values decreased from day 0 to day +14 both in the treatment and control groups, but were lower in the former. The non-responder group had higher dTE levels at day 2 compared to responders (p = 0.019).

CONCLUSION

BR55 appears to be useful in the prediction of response to sorafenib in a xenograft model of HCC.

Targeted therapy: resistance and re-sensitization

The last two decades have witnessed a paradigm shift from cytotoxic drugs to targeted therapy in medical oncology and pharmaceutical innovation. Inspired by breakthroughs in molecular and cellular biology, a number of novel synthesized chemical compounds and recombinant antibodies have been developed to selectively target oncogenic signaling pathways in a broad array of tumor types. Although targeted therapeutic agents show impressive clinical efficacy and minimized adverse effects compared with traditional treatments, the challenging drug-resistant issue has also emerged to limit their benefits to cancer patients. In this regard, we aim to improve targeted therapy by presenting a systematic framework regarding the drug resistance mechanisms and alternative approaches to re-sensitize cancer cells/tissues therapeutically.

Vintafolide: a novel targeted therapy for the treatment of folate receptor expressing tumors

Despite advances in the development of molecularly targeted therapies, limited improvements in overall survival have been noted among many cancer patients with solid tumors, primarily due to development of drug resistance. Accordingly, there is an unmet need for new targeted therapies and treatment approaches for cancer, especially for overcoming resistance. Expression of the folate receptor is upregulated in many tumor types and thus represents an ideal target for cancer treatment. Several folate receptor targeted therapies are in development, including the small molecule drug conjugate vintafolide, the monoclonal antibody farletuzumab, and the antibody-drug conjugate IMGN853. The role of the folate receptor as a target in cancer progression and resistance as well as emerging preclinical and clinical data from studies on those folate receptor targeted agents that are in development with a focus on vintafolide are reviewed. The folate receptor has several unique properties, such as high expression in several tumor types, that make it a rational target for cancer treatment, and allow for selective delivery of folate receptor targeted agents. Early-stage clinical data in lung and ovarian cancer suggest that vintafolide has the potential for combination with other standard approved agents.

Genetic variations in angiopoietin and pericyte pathways and clinical outcome in patients with resected colorectal liver metastases

BACKGROUND

Genes involved in the angiopoietin and pericyte pathways may become escape mechanisms under antivascular endothelial growth factor (anti-VEGF) therapy. The authors investigated whether variations within genes in these pathways are associated with clinical outcome in patients with colorectal liver metastases who undergo liver resection and receive perioperative, bevacizumab-based chemotherapy.

METHODS

Single nucleotide polymorphisms (SNPs) in 9 genes (angiopoietin-1 [ANGPT1]; ANGPT2; TEK tyrosine kinase, endothelial [TEK]; platelet-derived growth factor β [PDGFB]; β-type platelet-derived growth factor receptor [PDGFRB]; insulin-like growth factor 1 [IGF1]; transforming growth factor β1 [TGFB1]; RalA binding protein 1 [RALBP1]; and regulator of G-protein signaling 5 [RGS5]) were analyzed in samples of genomic DNA from 149 patients and were evaluated for associations with clinical outcome.

RESULTS

RALBP1 reference SNP 329007 (rs329007) A>G resulted in a significant difference in recurrence-free survival (A/A genotype, 14.0 months; A/G or G/G genotype, 9.2 months; hazard ratio [HR], 1.60; P = .024). PDGFB rs1800818 A>G was associated with 3-year overall survival rates (A/A genotype, 78%; A/G genotype, 69%; [HR 1.37]; G/G genotype, 53%; [HR 2.12]; P = .048). In multivariate analysis, RALBP1 rs329007 A>G remained significant (HR, 1.99; P = .002). PDGFB rs1800818 A>G and RALBP1 rs329007 A>G were correlated with radiologic response (A/A or A/G genotype, 86%; G/G genotype, 71% [P = .042]; A/A genotype, 78%; A/G or G/G genotype, 94% [P = .018], respectively). RALBP1 rs329007 A>G demonstrated significantly different rates of histologic response (A/A genotype: major histologic response, 35%; partial histologic response, 34%; no histologic response, 30%; A/G or G/G genotype: 46%, 13%, and 41%, respectively; P = .029). Recursive partitioning analysis revealed that ANGPT2 rs2442599 T>C and RALBP1 rs329007 A>G were the main SNPs that predicted histologic response and recurrence-free survival, whereas PDGFB rs1800818 A>G was the leading SNP that predicted overall survival. ANGPT2 rs2916702 C>T and rs2442631 G>A were significantly associated with the probability of achieving a cure.

CONCLUSIONS

The current data suggest that variations in genes involved in the angiopoietin and pericyte pathways may be predictive and/or prognostic biomarkers in patients with resected colorectal liver metastases who receive bevacizumab-based chemotherapy.

Nek6 and Hif-1α cooperate with the cytoskeletal gateway of drug resistance to drive outcome in serous ovarian cancer

Hypoxia selects the most aggressive and drug-resistant clones in solid malignancies. One of the pivotal transcription factors induced by hypoxia is Hif-1α. However, in serous ovarian cancer (SEOC), Hif-1α expression is not a prognostic biomarker. This study aims to assess the hypothesis that the serine-threonine kinase Nek6 functions as a downstream effector cooperating with Hif-1α in driving ovarian cancer aggressiveness. Nek6 was overexpressed and Hif-1α was silenced in A2780 cells. Nek6 was also stably silenced in Hey cells. The dependence of Nek6 expression on Hif-1α was assayed as a function of hypoxic growth conditions. Nek6 interaction with the cytoskeletal gateway of drug resistance was investigated with far western blot. The co-expression of NEK6, HIF1A, TUBB3 and GBP1 transcripts was quantified with qPCR in two cohorts of SEOC patients (346 locally treated patients and 344 from the TCGA dataset). Nek6 expression is induced by hypoxia in a Hif-1α dependent fashion. Nek6 directly interacts with GBP-1, thus being a component of the cytoskeletal gateway of drug resistance. Nek6 overexpression increases and silencing decreases the anchorage-independent growth of cultured cells. In SEOC patients, NEK6 expression is significantly correlated with HIF1A. Co-expression of NEK6, HIF1A, TUBB3 and GBP1 transcripts identifies a subset of SEOC patients characterized by poor outcome and drug resistance. This study demonstrates the functional relevance of Nek6 in the context of the adaptive response to hypoxia in SEOC. This finding may help identify a sub-population of patients at high risk of relapse to standard first-line chemotherapy.

Dual effects of a targeted small-molecule inhibitor (cabozantinib) on immune-mediated killing of tumor cells and immune tumor microenvironment permissiveness when combined with a cancer vaccine

Background

Growing awareness of the complexity of carcinogenesis has made multimodal therapies for cancer increasingly compelling and relevant. In recent years, immunotherapy has gained acceptance as an active therapeutic approach to cancer treatment, even though cancer is widely considered an immunosuppressive disease. Combining immunotherapy with targeted agents that have immunomodulatory capabilities could significantly improve its efficacy.

Methods

We evaluated the ability of cabozantinib, a receptor tyrosine kinase inhibitor, to modulate the immune system in vivo as well as alter the phenotype of tumor cells in vitro in order to determine if this inhibitor could act synergistically with a cancer vaccine.

Results

Our studies indicated that cabozantinib altered the phenotype of MC38-CEA murine tumor cells, rendering them more sensitive to immune-mediated killing. Cabozantinib also altered the frequency of immune sub-populations in the periphery as well as in the tumor microenvironment, which generated a more permissive immune environment. When cabozantinib was combined with a poxviral-based cancer vaccine targeting a self-antigen, the combination significantly reduced the function of regulatory T cells and increased cytokine production from effector T cells in response to the antigen. These alterations to the immune landscape, along with direct modification of tumor cells, led to markedly improved antitumor efficacy.

Conclusions

These studies support the clinical combination of cabozantinib with immunotherapy for the treatment of cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-014-0294-y) contains supplementary material, which is available to authorized users.

MicroRNAs as novel predictive biomarkers and therapeutic targets in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer in western countries. Despite significant improvement in available treatment options, CRC still remains the second leading cause of cancer-related death. Traditionally, 5-fluorouracil has been used as the main chemotherapy drug for treatment of metastatic CRC (mCRC). However, during the last two decades more effective chemotherapeutic agents such as oxaliplatin, irinotecan and the monoclonal antibodies cetuximab, panitumumab and bevacizumab have been used in clinical practice. More recently, the therapeutic armamentarium has been supplemented by the monoclonal antibodies bevacizumab, cetuximab and panitumumab as well as the protein-trap aflibercept and the small molecule multi-kinase inhibitor regorafenib. One of the major problems for the management of CRC is the inherent or acquired resistance to therapeutic approaches. The discovery of microRNAs (miRNAs), a class of small, endogenous, non-coding, single-stranded RNAs that play a role as post-transcriptional regulators, has added new dimensions to the diagnosis and treatment of cancer. Because miRNAs are important regulators of carcinogenesis, progression, invasion, angiogenesis and metastases in CRC, they might serve as potential predictive and prognostic factors and even as therapeutic targets themselves. Several miRNAs are already known to be dysregulated in CRCs and have been linked to biological processes involved in tumor progression and response to anti-cancer therapies. This review summarizes current therapeutic approaches for treating CRC and highlights the role of miRNAs as novel predictive biomarkers and potential drug targets in CRC patients.

Radioiodine therapy for thyroid cancer in the era of risk stratification and alternative targeted therapies

Differentiated thyroid cancers are typically iodine-avid and can be effectively treated with radioiodine. In most patients, radioiodine treatment is done for ablation of residual tissue, and in these cases the focus should be on using the minimum effective dose. Adjuvant therapy can be done to reduce the risk of recurrence, but optimal patient selection and dose are unclear. Patients with advanced disease benefit most from treatment with the maximum-tolerated dose. Recent research has focused on better patient selection and reduced radioiodine doses for remnant ablation. There are emerging targeted therapeutic approaches in patients who are appropriately shown to have iodine-refractory disease, with 1 drug approved by the Food and Drug Administration. Numerous trials are ongoing to assess targeted therapeutics alone or in combination with radioiodine.

The preparation of VEGFR1/CD3 bispecific antibody and its specific cytotoxicity against VEGFR1-positive breast cancer cells

Bispecific antibody (BsAb) has been proved to be a very effective antitumor approach because of its distinctive advantages of immune-mediated cytotoxicity. To enhance the ability to recruit and activate T lymphocytes for tumor-specific killing, we constructed and prepared a recombinant human single-chain Fv bispecific antibody (BsAb), named VEGFR1/CD3 BsAb, targeting VEGFR1 and CD3. The VEGFR1/CD3 BsAb was expressed in CHO-K1 cells and purified by Ni-NTA affinity chromatography. The CD3 and VEGFR1-binding activity of VEGFR1/CD3 BsAb was confirmed by flow cytometry. T lymphocyte activation and proliferation induced by VEGFR1/CD3 BsAb were also demonstrated in vitro. Notably, our VEGFR1/CD3 BsAb presented a powerful and specific killing effect against VEGFR1-positive human breast cancer cell MDA-MB-231 and MDA-MB-435 through activating T lymphocyte at very low concentrations, indicating that it will be a valuable antibody drug for treatment of VEGFR1-positive cancers in the future.

Metabolic effects of antiangiogenic drugs in tumors: therapeutic implications

Antiangiogenic therapy has become a mainstay of cancer therapeutics, but clinical responses are generally short-term owing to the development of secondary resistance. Tumor starvation by antiangiogenic drugs is largely attributed to increased hypoxia and impaired nutrients supply, suggesting that angiogenesis inhibition causes remarkable metabolic perturbations in the tumor microenvironment. We review here recent acquisitions concerning metabolic effects of angiogenesis blockade in tumors and discuss the possibility that some metabolic features of tumor cells - i.e. their dependency from glucose as primary energy substrate - might affect tumor responses to anti-vascular endothelial growth factor treatment. Moreover, we discuss the hypothesis that anti-angiogenic therapy might foster metabolic evolution of tumors. The therapeutic implications of this hypothesis will be discussed further here.

Sequencing of antiangiogenic agents in the treatment of metastatic colorectal cancer

Significant advances have been made with respect to our understanding of the critical role of agents targeting angiogenic pathways in the treatment of metastatic colorectal cancer (mCRC). The approval of 3 agents that target angiogenic signaling, bevacizumab, ziv-aflibercept, and regorafenib, provides strong evidence that angiogenesis is an important process in mCRC. The addition of bevacizumab to combination chemotherapy in the first- and second-line treatment of mCRC has resulted in meaningful improvement in overall and progression-free survival. The standard of care for mCRC has evolved to incorporate cytotoxic chemotherapy as the backbone regimens (eg, FOLFOX [folinic acid, 5-fluorouracil, and oxaliplatin], FOLFIRI [folinic acid, 5-fluorouracil, and irinotecan]) with or without bevacizumab, and epidermal growth factor receptor-targeted therapies (eg, cetuximab, panitumumab) in the setting of wild-type KRAS. The development of ziv-aflibercept in combination with FOLFIRI has improved clinical efficacy in the second-line treatment of mCRC. Regorafenib, a small-molecule multikinase inhibitor, has recently been approved by the US Food and Drug Administration as single-agent therapy in the treatment of refractory and progressive mCRC. Each of these agents has been integrated into an evidence-based-albeit, still evolving-treatment continuum for initial treatment, treatment after first progression, and treatment after second progression. However, the most effective strategy for the use of these agents, and others in development remains unclear. This review provides an overview of the current clinical evidence for the use of antiangiogenic agents targeting in the treatment of mCRC.

Fucoidan as a marine anticancer agent in preclinical development

Fucoidan is a fucose-containing sulfated polysaccharide derived from brown seaweeds, crude extracts of which are commercially available as nutritional supplements. Recent studies have demonstrated antiproliferative, antiangiogenic, and anticancer properties of fucoidan in vitro. Accordingly, the anticancer effects of fucoidan have been shown to vary depending on its structure, while it can target multiple receptors or signaling molecules in various cell types, including tumor cells and immune cells. Low toxicity and the in vitro effects of fucoidan mentioned above make it a suitable agent for cancer prevention or treatment. However, preclinical development of natural marine products requires in vivo examination of purified compounds in animal tumor models. This review discusses the effects of systemic and local administration of fucoidan on tumor growth, angiogenesis, and immune reaction and whether in vivo and in vitro results are likely applicable to the development of fucoidan as a marine anticancer drug.

Tumor resistance to anti-VEGF therapy through up-regulation of VEGF-C expression

Increasing evidence has indicated that prolonged use of anti-VEGF (vascular endothelial growth factor) agents for cancer therapy promotes tumor resistance. To gain insight into the molecular mechanism underlying resistance to anti-VEGF therapy, we developed a mouse Lewis lung carcinoma (LLC) cell line that is resistant to treatment with a potent VEGF inhibitor, VEGF-Trap, through repeated in vivo selection. We compared the transcriptome profiles of resistant and non-resistant tumor cells using RNA-seq analysis. VEGF-C was significantly up-regulated in resistant tumor cells, as determined by quantitative real-time PCR and immunohistochemical analyses. Inhibition of VEGF-C in resistant cells suppressed endothelial cell migration in vitro and partially restored sensitivity to VEGF-Trap treatment in vivo. Our findings indicate that tumors may develop resistance to anti-VEGF therapy by activating the VEGF-C pathway.

MicroRNA-192 suppresses liver metastasis of colon cancer

Metastasis causes most deaths from colon cancer yet mechanistic understanding and therapeutic options remain limited. Here we show that expression of microRNA (miR)-192 is inversely correlated with metastatic potential of colon cancer cells. Ectopic expression of miR-192 sensitizes colon cancer cells to growth factor deprivation stress (GFDS)-induced apoptosis whereas inhibition of miR-192 confers resistance. Overexpression of miR-192 inhibits metastatic colonization to the liver in an orthotopic mouse model of colon cancer. Alterations associated with the metastatic phenotype in the primary tumors include increased apoptosis, decreased proliferation and angiogenesis. Further studies indicate that miR-192 down-regulates expression of Bcl-2, Zeb2 and VEGFA in vitro and in vivo, which is responsible for enhanced apoptosis, increased expression of E-cadherin and decreased angiogenesis in vivo respectively. Finally, studies performed on human colonic adenocarcinoma show that expression of miR-192 is significantly reduced in neoplastic cells as compared to normal colonic epithelium. Importantly, there is a significant decrease of miR-192 expression in stage IV tumors when compared to stage I or II lesions. These findings indicate that miR-192 plays an important role in colon cancer development and progression. Our studies underscore the clinical relevance and prognostic significance of miR-192 expression in colon cancer. Therefore, a major implication of our studies is that restoration of miR-192 expression or antagonism of its target genes (Bcl-2, Zeb2 or VEGFA) may have considerable therapeutic potential for anti-metastatic therapy in patients with colon cancer.

Oral multikinase inhibitor regorafenib for the treatment of patients with metastatic colorectal cancer

SUMMARY Regorafenib is an oral small molecule inhibitor of multiple kinases involved in pathogenic processes, such as oncogenesis, tumor angiogenesis and maintenance of the tumor microenvironment, whose efficacy has been recently demonstrated in the treatment of pretreated metastatic colorectal cancer patients. The introduction of regorafenib into clinical practice allows medical oncologists to offer a new line of therapy to patients who have already received all of the other available drugs. Nevertheless, some issues deserve to be further examined in order to improve our knowledge of this drug’s potentialities and to better integrate its use in the daily routine, including the evaluation of response beyond convential size-based response evaluation criteria in solid tumors, the identification of molecular predictors of benefit, and the investigation of the potential role of regorafenib in different settings and in combination with other agents.

Endoglin is necessary for angiogenesis in human ovarian carcinoma-derived primary endothelial cells

Endoglin (CD105, END) is upregulated in proliferating endothelial cells, suggesting potential therapeutic properties. However, it is not clear whether endoglin mediates an enhanced proliferative rate or may be upregulated as part of a negative feedback loop. To gain insights into context-dependent and cell type-dependent regulatory effects of endoglin, we studied its role properties in human ovarian carcinoma-derived endothelial cells (ODMECs). We isolated and cultured primary ODMECs from epithelial ovarian carcinoma tissue. ODMECs had higher expression of endoglin and VEGFR-2, and also exhibited enhanced spontaneous formation of vessel-like structures in vitro. Transfection of siRNA targeting endoglin in ODMECs cells resulted in the reduction of the proliferation and tube formation. These results indicate that a subset of ODMECs display abnormal angiogenic properties and this phenotype was blocked by decreasing endoglin levels, suggesting endoglin is essential for stimulating angiogenesis, and targeting it may be an attractive approach to anti-angiogenesis therapy for ovarian carcinoma.

Prospective validation of candidate SNPs of VEGF/VEGFR pathway in metastatic colorectal cancer patients treated with first-line FOLFIRI plus bevacizumab

PURPOSE

The potential impact of different SNPs of VEGF/VEGFR pathway on the clinical outcome of mCRC patients receiving bev-containing regimens has been investigated in retrospective experiences with contrasting results. We previously reported the association of VEGFA rs833061 C/T variants with PFS in metastatic colorectal cancer patients treated with first-line FOLFIRI plus bevacizumab. The primary objective of this work was to prospectively validate that retrospective finding. A confirmatory analysis of other SNPs of VEGF/VEGFR pathway genes was included.

EXPERIMENTAL DESIGN

To detect a HR for PFS of 1.7 for VEGFA rs833061 T/T compared to C- variants in metastatic colorectal cancer patients treated with first-line FOLFIRI plus bevacizumab, setting two-sided α = 0.05 and β = 0.20, 199 events were required. VEGFA rs699946 A/G, rs699947 A/C, VEGFR1 rs9582036 A/C and rs7993418 A/G, VEGFR2 rs11133360 C/T, rs12505758 C/T and rs2305948 C/T and EPAS1 rs4145836 A/G were also tested. Germ-line DNA was extracted from peripheral blood. SNPs were analyzed by PCR and sequencing.

RESULTS

Four-hundred-twenty-four pts were included. At the univariate analysis, no differences according to VEGFA rs833061 C/T variants were observed in PFS (p = 0.38) or OS (p = 0.95). Among analyzed SNPs, only VEGFR2 rs12505758 C- variants, compared to T/T, were associated to shorter PFS (HR: 1.36 [1.05-1.75], p = 0.015, dominant genetic model) and OS, with a trend toward significance (HR: 1.34 [0.95-1.88], p = 0.088). In the multivariate model, this association retained significance (HR: 1.405 [1.082-1.825], p = 0.012) in PFS, that was lost by applying multiple testing correction (p = 0.14).

CONCLUSION

This prospective experience failed to validate the hypothesized predictive impact of VEGFA rs833061 variants. Retrospective findings on different candidate SNPs were not confirmed. Only VEGFR2 rs12505758 variants, whose prognostic and not predictive impact was previously reported, correlated with PFS. Given the complexity of angiogenesis, it is rather unlike that a single germ-line SNP might be a good predictor of benefit from bevacizumab.

Dose selection trial of metronomic oral vinorelbine monotherapy in patients with metastatic cancer: a hellenic cooperative oncology group clinical translational study

Background

Metronomic chemotherapy is considered an anti-angiogenic therapy that involves chronic administration of low-dose chemotherapy at regular short intervals. We investigated the optimal metronomic dose of oral vinorelbine when given as monotherapy in patients with metastatic cancer.

Methods

Patients with recurrent metastatic breast (BC), prostate (PC) or non-small cell lung cancer (NSCLC) and adequate organ functions were randomly assigned to 30, 40 or 50 mg vinorelbine, taken orally three times a week. Treatment continued until disease progression, unacceptable toxicity, withdrawal of consent or maximum 24 months. Primary endpoint was time-to-treatment failure (TTF) and secondary were progression-free survival (PFS), toxicity, changes in blood concentrations of angiogenesis-associated biomarkers and pharmacokinetics.

Results

Seventy-three patients were enrolled. Four-month TTF rate did not differ between the three arms: 25.9% (11.1%-46.2% 95% Confidence Interval), 33.3% (15.6%-55.3%) and 18.2% (5.2%-40.3%) for the 30 mg, 40 mg and 50 mg arms (p-value = 0.56). Objective response was seen in 2 patients with NSCLC (treated at 30 and 50 mg respectively), one with BC (at 40 m g) and one with PC (at 50 mg) and lasted from 4 to 100 weeks, with maximum response duration achieved at 50 mg. Adverse events were mild and negligible and did not differ between the three arms. Blood levels of vinorelbine reached steady state from the second week of treatment and mean values for the 30, 40 and 50 mg were respectively 1.8 ng/ml (SD 1.10), 2.2 ng/ml (SD 1.87) and 2.6 ng/ml (SD 0.69). Low pre-treatment blood concentrations of FGF2 and IL8 predicted favorable response to therapy (p values 0.02 and 0.006, respectively), while high levels of TEK gene transcript predicted treatment resistance.

Conclusions

Considering the antitumor activity and response duration, the negligible toxicity of the highest dose investigated and the lack of drug accumulation over time, we suggest that 50 mg given three times a week is the optimal dose for metronomic oral vinorelbine. Further investigation of metronomic oral vinorelbine (MOVIN) at this dose is warranted in combination with conventional chemotherapy regimens and targeted therapies.

Trial registration

Clinicaltrials.gov NCT00278070

TGF-Beta suppresses VEGFA-mediated angiogenesis in colon cancer metastasis

The FET cell line, derived from an early stage colon carcinoma, is non-tumorigenic in athymic nude mice. Engineered FET cells that express TGF-α (FETα) display constitutively active EGFR/ErbB signaling. These cells readily formed xenograft tumors in athymic nude mice. Importantly, FETα cells retained their response to TGF-beta-mediated growth inhibition, and, like the parental FET cells, expression of a dominant negative TGF-beta type II receptor (DNRII) in FETα cells (FETα/DNRII) abrogated responsiveness to TGF-beta-induced growth inhibition and apoptosis under stress conditions in vitro and increased metastatic potential in an orthotopic model in vivo, which indicates metastasis suppressor activity of TGF-beta signaling in this model. Cancer angiogenesis is widely regarded as a key attribute for tumor formation and progression. Here we show that TGF-beta signaling inhibits expression of vascular endothelial growth factor A (VEGFA) and that loss of autocrine TGF-beta in FETα/DNRII cells resulted in increased expression of VEGFA. Regulation of VEGFA expression by TGF-beta is not at the transcriptional level but at the post-transcriptional level. Our results indicate that TGF-beta decreases VEGFA protein stability through ubiquitination and degradation in a PKA- and Smad3-dependent and Smad2-independent pathway. Immunohistochemical (IHC) analyses of orthotopic tumors showed significantly reduced TGF-beta signaling, increased CD31 and VEGFA staining in tumors of FETα/DNRII cells as compared to those of vector control cells. These results indicate that inhibition of TGF-beta signaling increases VEGFA expression and angiogenesis, which could potentially contribute to enhanced metastasis of those cells in vivo. IHC studies performed on human colon adenocarcinoma specimens showed that TGF-beta signaling is inversely correlated with VEGFA expression, indicating that TGF-beta-mediated suppression of VEGFA expression exists in colon cancer patients.

Bevacizumab plus chemotherapy as salvage treatment in chemorefractory patients with metastatic colorectal cancer

Purpose

The combination of chemotherapy and bevacizumab, a monoclonal antibody targeting the vascular endothelial growth factor, is consistently being used as first- and second-line treatment in patients with metastatic colorectal cancer (mCRC). There is little data of the activity of bevacizumab in chemorefractory mCRC patients. The aim of this retrospective single center study was to evaluate the activity of bevacizumab combined with chemotherapy in this study population.

Methods

Forty-six consecutive mCRC patients treated in the University Hospital Gasthuisberg (Leuven, Belgium) receiving bevacizumab in advanced lines following failure of conventional chemotherapy were included in this study. Treatment regimen consisted of bevacizumab 5 mg/kg in combination with leucovorin, 5-fluorouracil, and oxaliplatin (FOLFOX) or leucovorin, 5-fluorouracil, and irinotecan (FOLFIRI).

Results

Bevacizumab plus chemotherapy was used in third-line treatment in eight (17%) patients and in fourth-line treatment or more in 38 patients (83%). All patients previously failed irinotecan-based chemotherapy, 44 (96%) failed oxaliplatin-based regimens, and 40 (87%) failed treatment with cetuximab. Bevacizumab was given in combination with irinotecan-based chemotherapy in 36 patients, oxaliplatin-based chemotherapy in nine patients, and with single agent 5-fluorouracil in one patient. Objective response was demonstrated in ten patients (22%) and disease control in 38 (83%) with a median progression-free survival of 8.9 months and a median overall survival of 13.8 months. Only four patients experienced grade III and above bevacizumab-related toxicity.

Conclusion

Taking into account the retrospective nature of the study which can influence the selection of patients, bevacizumab given in advanced lines after failure of conventional chemotherapy and antiepidermal growth factor receptor agents can result in high disease control rates in patients with mCRC.

Targeted therapy for metastatic colorectal cancer: role of aflibercept

Worldwide, colorectal cancer (CRC) is the third most commonly diagnosed cancer in male individuals and the second most commonly diagnosed cancer in female individuals. Survival outcomes are less than optimal for patients with metastatic disease, with a 5-year survival in the 5% to 8% range. The development of new chemotherapeutic agents and effective combination regimens for metastatic colorectal cancer (mCRC) has increased median overall survival (OS) to the 24- to 28-month range. Because of the recognition that vascular endothelial growth factors (VEGFs) and their receptors are primary regulators of physiologic and pathologic angiogenesis and lymphangiogenesis, leading to neovascularization and tumor growth, the targeting of the angiogenic pathway has become a focus of key therapeutic strategies in mCRC. Therapeutic regimens that include bevacizumab, an inhibitor of VEGF-A, in combination with cytotoxic chemotherapy, have resulted in improved response rate (RR) and survival in mCRC. However, the effects of VEGF-A inhibition are often temporary, with resistance and disease progression developing in most patients. Proposed models include intrinsic and adaptive resistance, mediated by factors other than VEGF-A. Aflibercept (known as ziv-aflibercept in the United States; Zaltrap®, Regeneron Pharmaceuticals; sanofi-aventis), a novel recombinant fusion protein, is an angiogenic factor trap that blocks the binding of VEGF-A, VEGF-B, and placental growth factor. Phase I/II clinical trials have demonstrated effective activity in mCRC, with acceptable safety and tolerability. A recent phase III randomized double-blind trial in patients previously treated with oxaliplatin reported significant improvement in OS, progression-free survival (PFS), and RR with aflibercept compared with placebo when administered in combination with irinotecan and fluorouracil. Adverse events were consistent with anti-VEGF therapy. Thus aflibercept represents a potential new treatment option for patients with mCRC.