The effect of VEGF-targeted therapy on biomarker expression in sequential tissue from patients with metastatic clear cell renal cancer

A novel decoy receptor fusion protein for FGF-2 potently inhibits tumour growth

BACKGROUND

Antiangiogenic therapies have been proven effective in cancer treatment. Fibroblast growth factor-2 (FGF-2) has been functionally implicated in tumour angiogenesis and is an important target of antiangiogenic therapies. The aim of this work was to develop a novel FGF-2 inhibitor for cancer therapy.

METHODS

Eleven fusion proteins were developed by fusing various truncated extracellular regions of FGFR1 with the Fc region of IgG1. The optimal decoy receptor fusion protein with the highest binding affinity for FGF-2 was identified by an FGF-2-binding assay and its potential antitumour effects were investigated.

RESULTS

We obtained a soluble decoy receptor fusion protein with the highest binding activity for FGF-2, named FGF-Trap. Fibroblast growth factor-Trap significantly abolished FGF-2-stimulated activation of FGF signalling as demonstrated by its suppression of FGF-2-mediated phosphorylation of Erk1/2 and Akt, upregulation of cyclins D1 and E and the increase in mRNA levels of vascular endothelial growth factor R1 and R2 (VEGFR1 and VEGFR2). Furthermore, FGF-Trap effectively suppressed FGF-2-induced proliferation and migration of human umbilical vein endothelial cells (HUVECs) in vitro. Most importantly, FGF-Trap potently inhibited tumour growth and angiogenesis in Caki-1 and A549 xenograft models in vivo.

CONCLUSIONS

Fibroblast growth factor-Trap potently inhibits tumour growth by blocking FGF-2 signalling pathways and could be an effective therapeutic agent for cancer patients.

Carbonic anhydrase 9 expression increases with vascular endothelial growth factor-targeted therapy and is predictive of outcome in metastatic clear cell renal cancer

Background

There is a lack of biomarkers to predict outcome with targeted therapy in metastatic clear cell renal cancer (mccRCC). This may be because dynamic molecular changes occur with therapy.

Objective

To explore if dynamic, targeted-therapy-driven molecular changes correlate with mccRCC outcome.

Design, setting, and participants

Multiple frozen samples from primary tumours were taken from sunitinib-naïve (n = 22) and sunitinib-treated mccRCC patients (n = 23) for protein analysis. A cohort (n = 86) of paired, untreated and sunitinib/pazopanib-treated mccRCC samples was used for validation. Array comparative genomic hybridisation (CGH) analysis and RNA interference (RNAi) was used to support the findings.

Intervention

Three cycles of sunitinib 50 mg (4 wk on, 2 wk off).

Outcome measurements and statistical analysis

Reverse phase protein arrays (training set) and immunofluorescence automated quantitative analysis (validation set) assessed protein expression.

Results and limitations

Differential expression between sunitinib-naïve and treated samples was seen in 30 of 55 proteins (p < 0.05 for each). The proteins B-cell CLL/lymphoma 2 (BCL2), mutL homolog 1 (MLH1), carbonic anhydrase 9 (CA9), and mechanistic target of rapamycin (mTOR) (serine/threonine kinase) had both increased intratumoural variance and significant differential expression with therapy. The validation cohort confirmed increased CA9 expression with therapy. Multivariate analysis showed high CA9 expression after treatment was associated with longer survival (hazard ratio: 0.48; 95% confidence interval, 0.26–0.87; p = 0.02). Array CGH profiles revealed sunitinib was associated with significant CA9 region loss. RNAi CA9 silencing in two cell lines inhibited the antiproliferative effects of sunitinib. Shortcomings of the study include selection of a specific protein for analysis, and the specific time points at which the treated tissue was analysed.

Conclusions

CA9 levels increase with targeted therapy in mccRCC. Lower CA9 levels are associated with a poor prognosis and possible resistance, as indicated by the validation cohort.

Patient summary

Drug treatment of advanced kidney cancer alters molecular markers of treatment resistance. Measuring carbonic anhydrase 9 levels may be helpful in determining which patients benefit from therapy.

A systematic review of sequencing and combinations of systemic therapy in metastatic renal cancer

CONTEXT

The introduction of novel molecular-targeted agents has revolutionised the management of patients with metastatic renal cell carcinoma (mRCC). However, uncertainties remain over sequential or simultaneous combination therapies.

OBJECTIVE

To systematically review relevant literature comparing the clinical effectiveness and harms of different sequencing and combinations of systemic targeted therapies for mRCC.

EVIDENCE ACQUISITION

Relevant databases (including Medline, Cochrane Library, trial registries, and conference proceedings) were searched (January 2000 to September 2013) including only randomised controlled trials (RCTs). Risk of bias assessment was performed. A qualitative and quantitative synthesis of the evidence was presented.

EVIDENCE SYNTHESIS

The literature search identified 5149 articles. A total of 24 studies reporting on 9589 patients were eligible for inclusion; data from four studies were included for meta-analysis. There were generally low risks of bias across studies; however, clinical and methodological heterogeneity prevented pooling of data for most studies. Overall, the data showed several targeted therapies were associated with an improvement in progression-free survival in patients with mRCC. There were limited data from RCTs regarding the issue of sequencing; studies on combination therapies have been hampered by difficulties with tolerability and safety.

CONCLUSIONS

Although the role of vascular endothelial growth factor/vascular endothelial growth factor receptor targeting therapies and mammalian target of rapamycin inhibition in the management of mRCC is now established, limited reliable data are available regarding sequencing and combination therapies. Although data from retrospective cohort studies suggest a potential benefit for sequencing systemic therapies, significant uncertainties remain. Presently, mRCC systemic treatment should follow international guidelines (such as the European Society for Medical Oncology, National Comprehensive Cancer Network, and European Association of Urology) for patients fit to receive several lines of systemic therapies.

PATIENT SUMMARY

We thoroughly examined the literature on the benefits and harms of combining drugs for the treatment of kidney cancer that has spread and on the sequence in which the drugs should be given.

Anti-angiogenic therapy for cancer: current progress, unresolved questions and future directions

Tumours require a vascular supply to grow and can achieve this via the expression of pro-angiogenic growth factors, including members of the vascular endothelial growth factor (VEGF) family of ligands. Since one or more of the VEGF ligand family is overexpressed in most solid cancers, there was great optimism that inhibition of the VEGF pathway would represent an effective anti-angiogenic therapy for most tumour types. Encouragingly, VEGF pathway targeted drugs such as bevacizumab, sunitinib and aflibercept have shown activity in certain settings. However, inhibition of VEGF signalling is not effective in all cancers, prompting the need to further understand how the vasculature can be effectively targeted in tumours. Here we present a succinct review of the progress with VEGF-targeted therapy and the unresolved questions that exist in the field: including its use in different disease stages (metastatic, adjuvant, neoadjuvant), interactions with chemotherapy, duration and scheduling of therapy, potential predictive biomarkers and proposed mechanisms of resistance, including paradoxical effects such as enhanced tumour aggressiveness. In terms of future directions, we discuss the need to delineate further the complexities of tumour vascularisation if we are to develop more effective and personalised anti-angiogenic therapies.