Emerging antiangiogenic agents in lung cancer

Plasma cytokine and angiogenic factor profiling identifies markers associated with tumor shrinkage in early-stage non-small cell lung cancer patients treated with pazopanib

There is an unmet need for pharmacodynamic and predictive biomarkers for antiangiogenic agents. Recent studies have shown that soluble vascular endothelial growth factor receptor 2 (sVEGFR2), VEGF, and several other soluble factors may be modulated by VEGF pathway inhibitors. We conducted a broad profiling of cytokine and angiogenic factors (CAF) to investigate the relationship between baseline CAF levels, CAF changes during treatment, and tumor shrinkage in early-stage non-small cell lung cancer (NSCLC) patients treated with pazopanib, an oral angiogenesis inhibitor targeting VEGFR, platelet-derived growth factor receptor, and c-kit. Plasma samples were collected before treatment and on the last day of therapy from 33 patients with early-stage NSCLC participating in a single-arm phase II trial. Levels of 31 CAFs were measured by suspension bead multiplex assays or ELISA and correlated with change in tumor volume. Pazopanib therapy was associated with significant changes of eight CAFs; sVEGFR2 showed the largest decrease, whereas placental growth factor underwent the largest increase. Increases were also observed in stromal cell-derived factor-1alpha, IP-10, cutaneous T-cell-attracting chemokine, monokine induced by IFN-gamma, tumor necrosis factor-related apoptosis-inducing ligand, and IFN-alpha. Posttreatment changes in plasma sVEGFR2 and interleukin (IL)-4 significantly correlated with tumor shrinkage. Baseline levels of 11 CAFs significantly correlated with tumor shrinkage, with IL-12 showing the strongest association. Using multivariate classification, a baseline CAF signature consisting of hepatocyte growth factor and IL-12 was associated with tumor response to pazopanib and identified responding patients with 81% accuracy. These data suggest that CAF profiling may be useful for identifying patients likely to benefit from pazopanib, and merit further investigation in clinical trials.

DCE-MRI assessment of the effect of vandetanib on tumor vasculature in patients with advanced colorectal cancer and liver metastases: a randomized phase I study

BACKGROUND

Vandetanib is a once-daily oral inhibitor of VEGFR, EGFR and RET signaling pathways. In patients with advanced colorectal cancer and liver metastases, the effect of vandetanib on tumor vasculature was assessed using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

METHODS

Eligible patients received vandetanib 100 or 300 mg/day. DCE-MRI (iAUC(60 )and K(trans)) was used to quantify the primary endpoints of tumor perfusion and vascular permeability. An exploratory assessment of tumor oxygenation was performed using MRI/T2*. All MRI parameters were measured at baseline (twice) and on days 2, 8, 29 and 57.

RESULTS

Twenty-two patients received vandetanib (n = 10, 100 mg; n = 12, 300 mg). Baseline measurements of iAUC(60 )and K(trans )were reproducible, with low intrapatient coefficients of variation (11% and 24%, respectively). Estimates of mean % changes from baseline were -3.4% (100 mg) and -4.6% (300 mg) for iAUC(60), and -4.6% (100 mg) and -2.7% (300 mg) for K(trans); these changes were not significantly different between doses. The exploratory T2* measurement showed a significant increase at 300 mg versus 100 mg (P = 0.006). Both doses of vandetanib were generally well tolerated; common toxicities were fatigue, rash and diarrhea (majority CTC grade 1 or 2). The pharmacokinetic profile of vandetanib was similar to that observed previously. There were no RECIST-defined objective responses; five patients experienced stable disease >/=8 weeks.

CONCLUSION

In this study in patients with advanced colorectal cancer, vandetanib did not modulate gadolinium uptake in tumor vasculature and tissue measured by the DCE-MRI parameters iAUC(60 )and K(trans).

TRIAL REGISTRATION

NCT00496509 (ClinicalTrials.gov); D4200C00050 (AstraZeneca).

Efficacy and safety of axitinib in patients with advanced non-small-cell lung cancer: results from a phase II study

PURPOSE

This phase II study evaluated efficacy and safety of single-agent axitinib, an oral, potent, selective inhibitor of vascular endothelial growth factor receptors (VEGFR) -1, -2, and -3, in patients with advanced non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

This was an open-label, single-arm, multicenter, phase II study with a Simon two-stage minimax design. Patients received a starting dose of axitinib 5 mg orally BID. The primary end point was Response Evaluation Criteria in Solid Tumors (RECIST) -defined objective response rate. Secondary end points included safety and tolerability, overall survival (OS), and progression-free survival (PFS).

RESULTS

Thirty-two patients were enrolled, with a median age of 66.5 years. The majority of patients (75%) had adenocarcinoma. Nine patients (28%) had received no prior chemotherapy for metastatic disease, and 23 (72%) had received > or = one regimen. Three patients (9%) had a RECIST investigator-assessed, confirmed partial response (PR); disease control rate (PR + stable disease) was 41%. Median PFS was 4.9 months overall (95% CI, 3.6 to 7.0 months). Median OS was 14.8 months (95% CI, 10.7 months to not estimable) overall and 14.8 months (95% CI, 12.5 months to not estimable) in patients receiving first-line axitinib. One-year survival rates for patients with or without prior therapy for metastatic disease were 57% and 78%, respectively. Grade 3 treatment-related adverse events in > or = 5% of patients comprised fatigue (22%), hypertension (9%), and hyponatremia (9%).

CONCLUSION

Axitinib demonstrated single-agent activity in patients with advanced NSCLC. Therapy was well tolerated with manageable toxicities. Further investigation of this VEGFR inhibitor in NSCLC is of interest.

Multitarget drugs: the present and the future of cancer therapy

Target therapies for the treatment of human cancers have revolutionized the concept of oncological medicine. This type of therapeutic approach is directed to the inhibition of molecular targets that play a pivotal role in tumor progression -- such as tyrosine kinase receptors (TKIs) controlling cell proliferation and survival -- mainly by means of compounds able to block their activity. In the beginning, the aim of target therapies was specifically to hit a single molecule expressed in neoplastic cells. Now the prevailing idea is that inhibiting both cancer cells and cells of the stroma supporting the tumor would gain better results in fighting the disease. Therefore, the single-target therapy is fading in favor of a multitarget approach and the new generation of TKIs is selected on the basis of their ability simultaneously to target different molecules. This review summarizes the molecular basis of multitarget therapies and the most relevant results obtained in different cancer types.

Second-line treatment of advanced non-small cell lung cancer

After failure of first-line chemotherapy for advanced non-small cell lung cancer, many patients remain candidates to receive further antitumor treatment. To guide clinical management of these patients and to suggest priorities for clinical research, an International Panel of Experts met in Naples (Italy) in April 2007. Results and evidence-based conclusions are presented in this article. Single-agent chemotherapy with docetaxel or pemetrexed is the recommended option for unselected patients with performance status 0 to 2 who are candidates for second-line chemotherapy for advanced non-small cell lung cancer. Docetaxel has demonstrated superiority compared with best supportive care. Pemetrexed has been shown to be noninferior to docetaxel, with a more favorable toxicity profile. Erlotinib is effective in pretreated patients, and can be given second-line in patients not suitable or intolerant to chemotherapy, and in all patients as third-line treatment after failure of second-line chemotherapy. Gefitinib failed to show superiority to placebo as second- or third-line treatment, but it has been shown to be noninferior to docetaxel. In selected patients such as lifetime nonsmokers or those of East-Asian ethnicity, erlotinib, or gefitinib (where licensed) may be considered as second-line treatment even if they are fit for chemotherapy. Best supportive care in addition to active treatment remains important for all patients, but may be the exclusive option for patients unsuitable for more aggressive therapy. Further research is mandatory, to find better treatments, and to identify clinical and molecular predictive markers of efficacy, both for chemotherapy and for novel biologic agents.

Vascular endothelial growth factor receptor tyrosine kinase inhibitors vandetanib (ZD6474) and AZD2171 in lung cancer

Vascular endothelial growth factor (VEGF) is a rational target for advanced non-small cell lung cancer (NSCLC), a hypothesis validated by the recent Eastern Cooperative Oncology Group E4599 trial showing that the addition of the VEGF monoclonal antibody bevacizumab to chemotherapy prolongs overall survival. Several new tyrosine kinase inhibitors targeting the VEGF pathway are currently in advanced clinical development for NSCLC and offer several possible advantages compared with monoclonal antibodies, including oral administration, more flexible dosing, a broader spectrum of target inhibition, and different toxicity profiles. Among these agents, vandetanib (ZD6474), an inhibitor of the VEGF receptor (VEGFR)-2 and epidermal growth factor receptor tyrosine kinase, has been the most extensively studied. In a randomized phase II study of patients with platinum-refractory NSCLC, including squamous histology, vandetanib prolonged progression-free survival compared with gefitinib. In another phase II trial, an improvement in progression-free survival was observed for vandetanib in combination with docetaxel compared with docetaxel alone. AZD2171 is an inhibitor of VEGFR-1, VEGFR-2, and VEGFR-3 and other tyrosine kinases that has shown clinical activity in NSCLC in combination with carboplatin and paclitaxel. Several phase III trials are under way testing these agents either as monotherapy or in combination with chemotherapy in patients with lung cancer. Early results with these agents, and others being tested, raise the possibility that there will eventually be multiple VEGF-targeted therapies available in the clinic that can potentially benefit a broader range of patients with advanced-stage NSCLC.

Coexpression of receptor-tyrosine-kinases in gastric adenocarcinoma-a rationale for a molecular targeting strategy?

AIM: To define the (co-)expression pattern of target receptor-tyrosine-kinases (RTK) in human gastric adenocarcinoma.

METHODS: The (co-)expression pattern of VEGFR1-3, PDGFRα/β and EGFR1 was analyzed by RT-PCR in 51 human gastric adenocarcinomas. In addition, IHC staining was applied for confirmation of expression and analysis of RTK localisation.

RESULTS: The majority of samples revealed a VEGFR1 (98%), VEGFR2 (80%), VEGFR3 (67%), PDGFRα (82%) and PDGFRβ (82%) expression, whereas only 62% exhibited an EGFR1 expression. 78% of cancers expressed at least four out of six RTKs. While VEGFR1-3 and PDGFRα revealed a predominantly cytoplasmatic staining in tumor cells, accompanied by an additional nuclear staining for VEGFR3, EGFR1 was almost exclusively detected on the membrane of tumor cells. PDGFRβ was restricted to stromal pericytes, which also depicted a PDGFRα expression.

CONCLUSION: Our results reveal a high rate of receptor-tyrosine-kinases coexpression in gastric adenocarcinoma and might therefore encourage an application of multiple-target RTK-inhibitors within a combination therapy.

Tumor growth, angiogenesis and inflammation in mice lacking receptors for platelet activating factor (PAF)

Tumor growth is associated with angiogenesis and inflammation and the endogenous lipid, platelet activating factor (PAF), is a pro-inflammatory and pro-angiogenic mediator. We therefore measured tumor growth, angiogenesis and inflammation in normal (WT) mice and those lacking the receptor for PAF, through gene deletion (PAFR-KO). Growth of solid tumors derived from colon 26 cells was not altered but that from Ehrlich cells was markedly (5-fold) increased in the PAFR-KO mice, relative to the WT strain. Angiogenesis, as tumor content of VEGF or hemoglobin, was increased in both tumors from the mutant strain. Inflammation, as neutrophil and macrophage accumulation and chemokine (CXCL2 and CCL2) content of tumors, was decreased or unchanged in the tumors implying an overall decrease in the inflammatory response in the PAFR-KO strain. We also assessed growth of the Ehrlich tumor in its ascites form, after i.p. injection. Here growth (ascites volume) was inhibited by about 30%, but neutrophil and macrophage numbers were increased in the ascites fluid from the PAFR-KO mice. Angiogenesis in the peritoneal wall, which is not invaded by the tumor cells, was increased but leukocyte infiltration decreased in the mutant strain. Our results show, unexpectedly, that tumor-induced angiogenesis was increased in mice lacking response to PAF, from which we infer that in normal (WT) mice, PAF is anti-angiogenic. Further, although growth was still associated with angiogenesis in PAFR-KO mice, growth was not correlated with inflammation (leukocyte accumulation).

Vandetanib (ZD6474): an orally available receptor tyrosine kinase inhibitor that selectively targets pathways critical for tumor growth and angiogenesis

Vandetanib (ZD6474; ZACTIMA, AstraZeneca) is a once-daily, orally available agent with potential for use in a number of solid tumor types. Vandetanib targets key signaling pathways in cancer by inhibiting VEGFR-dependent tumor angiogenesis, and EGFR- and RET-dependent tumor cell proliferation and survival. Phase I studies showed vandetanib to be generally well tolerated at doses of < or = 300 mg/day, with a pharmacokinetic profile that supports once-daily oral administration. Phase II evaluation of vandetanib in patients with advanced refractory NSCLC has demonstrated improvements in progression-free survival both as monotherapy (versus gefitinib) and in combination with docetaxel (versus docetaxel alone). These positive outcomes have led to the initiation of Phase III trials of vandetanib in advanced NSCLC. Clinical development is also ongoing in other tumor types and encouraging evidence of antitumor activity has been reported in patients with metastatic hereditary medullary thyroid cancer.

Dual Targeting of the Vascular Endothelial Growth Factor and Epidermal Growth Factor Receptor Pathways: Rationale and Clinical Applications for Non-Small-Cell Lung Cancer

The vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) pathways represent 2 clinically validated targets for non-small-cell lung cancer (NSCLC), and there is strong biologic rationale for therapeutic approaches targeting both pathways in NSCLC and other diseases. These 2 pathways are interrelated, as VEGF is known to be downregulated by EGFR inhibition through hypoxia-inducible factor 1alpha-dependent and hypoxia-inducible factor 1alpha-independent mechanisms. Furthermore, acquired resistance to EGFR inhibitors is associated with increased levels of VEGF, and dual VEGF/EGFR inhibition has demonstrated activity in the presence of EGFR tyrosine kinase inhibitor-resistant disease. This approach is being investigated clinically using combinations of drugs that target the pathways separately, such as erlotinib and bevacizumab, or individual drugs that target both pathways, such as vandetanib. Randomized phase II studies in previously treated patients with NSCLC suggest that dual VEGF/EGFR inhibition might be more active than targeting either pathway alone and that the combination could also enhance the efficacy of chemotherapy. Phase III clinical trials are currently in progress to determine whether dual VEGF/EGFR inhibition, alone or in combination with chemotherapy, should become a standard therapeutic option for patients with NSCLC.