Immunotherapy in metastatic renal cell carcinoma

Impact of tivozanib on patient outcomes in treatment of advanced renal cell carcinoma

Renal cell carcinoma (RCC) is the most common type of kidney malignancy, and the clear-cell subtype represents the majority of RCCs. RCC is a heterogeneous disease in terms of genetic and histological features which determine the behavior of the disease. The von Hippel-Lindau (VHL) is a tumor suppressor gene and mutations of this gene are seen in 95% of clear-cell RCCs. Inactivation of VHL causes the accumulation of hypoxia-inducible factor-1 (HIF-1), and in turn, accumulation of HIF-1 induces overexpression of vascular endothelial growth factor (VEGF); the increase in VEGF expression makes RCC a highly vascularized tumor, and forms the rationale for antiVEGF treatment. In the past decade, improvement in the survival of RCC patients has been observed due to new effective therapies, such as antiVEGF and mammalian target of rapamycin (mTOR) targeting agents and immune checkpoint inhibitors. The majority of VEGF targeted agents are not just selective to VEGF receptors, but usually also have inhibitory effects on other kinases, such as c-KIT and FLT3. Tivozanib is an extremely potent and selective tyrosine kinase inhibitor (TKI) of VEGFR-1, 2, and 3, with a relatively long half-life, that is approved by the European Commission for the treatment of advanced/metastatic RCC. Tivozanib, at very low serum concentration can inhibit phosphorylation of VEGFR -1, -2, and -3 tyrosine kinase activity. This article summarizes the clinical data on tivozanib in the treatment of advanced/metastatic RCC.

Resistance to Targeted Therapies in Renal Cancer: The Importance of Changing the Mechanism of Action

Renal cell carcinoma (RCC) is a complex disease characterized by mutations in several genes. Loss of function of the von Hippel-Lindau (VHL) tumour suppressor gene is a very common finding in RCC and leads to up-regulation of hypoxia-inducible factor (HIF)-responsive genes accountable for angiogenesis and cell growth, such as platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF). Binding of these proteins to their cognate tyrosine kinase receptors on endothelial cells promotes angiogenesis. Promotion of angiogenesis is in part due to the activation of the phosphatidylinositol-3-kinase (PI3K)/AKT/mechanistic target of rapamycin (mTOR) pathway. Inhibition of this pathway decreases protein translation and inhibits both angiogenesis and tumour cell proliferation. Although tyrosine kinase inhibitors (TKIs) stand as the main first-line treatment option for advanced RCC, eventually all patients will become resistant to TKIs. Resistance can be overcome by using second-line treatments with different mechanisms of action, such as inhibitors of mTOR, c-MET, programmed death 1 (PD-1) receptor, or the combination of an mTOR inhibitor (mTORi) with a TKI. In this article, we briefly review current evidence regarding mechanisms of resistance in RCC and treatment strategies to overcome resistance with a special focus on the PI3K/AKT/mTOR pathway.

Sunitinib: Ten Years of Successful Clinical Use and Study in Advanced Renal Cell Carcinoma

The oral multikinase inhibitor sunitinib malate was approved by the U.S. Food and Drug Administration in January 2006 for use in patients with advanced renal cell carcinoma (RCC). Since then, it has been approved globally for this indication and for patients with imatinib-resistant or -intolerant gastrointestinal stromal tumors and advanced pancreatic neuroendocrine tumors. As we mark the 10-year anniversary of the beginning of the era of targeted therapy, and specifically the approval of sunitinib, it is worthwhile to highlight the progress that has been made in advanced RCC as it relates to the study of sunitinib. We present the key trials and data for sunitinib that established it as a reference standard of care for first-line advanced RCC therapy and, along with other targeted agents, significantly altered the treatment landscape in RCC. Moreover, we discuss the research with sunitinib that has sought to refine its role via patient selection and prognostic markers, improve dosing and adverse event management, and identify predictive efficacy biomarkers, plus the extent to which this research has contributed to the overall understanding and management of RCC. We also explore the key learnings regarding study design and data interpretation from the sunitinib studies and how these findings and the sunitinib development program, in general, can be a model for successful development of other agents. Finally, ongoing research into the continued and future role of sunitinib in RCC management is discussed.

THE ONCOLOGIST

2017;22:41-52 IMPLICATIONS FOR PRACTICE: Approved globally, sunitinib is established as a standard of care for first-line advanced renal cell carcinoma (RCC) therapy and, along with other targeted agents, has significantly altered the treatment landscape in RCC. Research with sunitinib that has sought to refine its role via patient selection and prognostic markers, improve dosing and adverse event management, and identify predictive efficacy biomarkers has contributed to the overall understanding and management of RCC. Key learnings regarding study design and data interpretation from the sunitinib studies and the sunitinib development program, in general, can be a model for the successful development of other agents.

Targeted therapies for treatment of renal cell carcinoma: recent advances and future perspectives

PURPOSE

A wide variety of targeted therapies are available for the treatment of renal cancer that has progressed beyond the point at which surgery is a viable option. In addition, there are many more that are in the different stages of clinical trials. Here, we provide a methodical discussion of the efficacy and safety of targeted therapies for the treatment of advanced renal cell carcinoma.

METHODS

We conducted a systematic literature employing the search terms: renal cell carcinoma targets, tyrosine kinase inhibitors, mammalian target of rapamycin inhibitors, and each of the drugs discussed within these papers.

RESULTS

The identified targeted therapies work by disrupting specific signalling pathways involved in tumour progression, such as those responsible for angiogenesis and cell proliferation. Tyrosine kinase inhibitors and mammalian target of rapamycin inhibitors are now established classes of drugs used in the treatment of renal cancer, with a total of six having received regulatory approval to date (sorafenib, sunitinib, pazopanib, axitinib, temsirolimus, and everolimus). Ongoing trials are likely to result in addition to these in the near future, for example, tivozanib, dovitinib, and cediranib. Furthermore, in addition to these small molecule drugs, immunotherapies involving monoclonal antibodies against signalling molecules such as vascular endothelial growth factor (bevacizumab) or programmed death-1 (nivolumab) are receiving increasing attention.

CONCLUSIONS

Targeted therapies have great potential for disrupting tumour progression by inhibiting certain signalling pathways. As our understanding of the biochemical pathways involved in cancer progresses, additional targets are certain to become apparent, expanding treatment options even further.

Cytoreductive nephrectomy in metastatic renal cell carcinoma

Metastatic renal cell carcinoma is associated with a poor prognosis and a median survival time of only 6-12 months. However, the emergence of immunotherapies has rekindled interest in cytoreductive nephrectomy as a therapeutic option. Phase III randomized trials have demonstrated that cytoreductive nephrectomy significantly improves overall survival in selected patients with metastatic renal cell carcinoma treated with interferon immunotherapy. While cytokine-based immunotherapy may be considered the standard systemic therapy, clinical studies are ongoing to develop molecular biomarkers and new therapies with improved efficacy and tolerability. With further advances in our understanding of the pathogenesis, behavior and molecular biology of renal cell carcinoma, cytoreductive nephrectomy, in combination with molecular targeted therapies, may become the new standard of care for patients with metastatic renal cell carcinoma.

Physalin F induces cell apoptosis in human renal carcinoma cells by targeting NF-kappaB and generating reactive oxygen species

Background

The aim of this study was to determine the molecular mechanisms of physalin F, an effective purified extract of Physalis angulata L. (Solanacae), in renal carcinoma A498 cells.

Methodology/Principal Findings

Physalin F was observed to significantly induce cytotoxicity of three human renal carcinoma A498, ACHN, and UO-31 cells in a concentration-dependent manner; this was especially potent in A498 cells. The physalin F-induced cell apoptosis of A498 cells was characterized by MTT assay, nuclear DNA fragmentation and chromatin condensation. Using flow cytometry analysis, physalin F induced A498 cell apoptosis as demonstrated by the accumulation of the sub-G1 phase in a concentration- and time-dependent manner. Moreover, physalin F-mediated accumulation of reactive oxygen species (ROS) caused Bcl-2 family proteins, Bcl-2, and Bcl-xL degradation, which led to disruption of mitochondrial membrane potential and release of cytochrome c from the mitochondria into the cytosol. These effects were associated with induction of caspase-3 and caspase-9 activity, which led to poly(ADP-ribose) polymerase cleavage. However, the antioxidant N-acetyl-_L-cysteine (NAC) and glutathione (GSH) resulted in the inhibition of these events and reversed physalin F-induced cell apoptosis. In addition, physalin F suppressed NF-κB activity and nuclear translocation of p65 and p50, which was reversed by NAC and GSH.

Conclusion

Physalin F induced cell apoptosis through the ROS-mediated mitochondrial pathway and suppressed NF-κB activation in human renal cancer A498 cells. Thus, physalin F appears to be a promising anti-cancer agent worthy of further clinical development.

[Metastatic renal cell cancer in Germany in 2010. Impact of different target therapies]

BACKGROUND

Since 2006 in Germany six different target drugs for therapy in metastatic renal cell cancer (mRCC) have been used. Comparative studies for the application with the same indication are absent, and the order of potential sequential therapy is up to now unclear. The aim of the study was to collect data on therapy decisions in Germany regarding mRCC in the age of "targeted therapy". At the same time the study addressed the central question of sequencing of the different therapy options. In addition, the data of this study were to be compared to a study already published in 2008.

PATIENTS AND METHODS

In 2010, four groups of doctors specialized in the therapy of patients with mRCC were asked for their behaviour in the first-, second- and third-line or sequential therapy. Those questioned included urologists in private practice (n=40), oncologists in private practice (n=40), hospital urologists (n=35) and hospital oncologists (n=35). Further the reasons for a therapy decision should be stated or weighted.

RESULTS

Altogether 92% of all patients with mRCC were treated. Urologists in private practice treat only 30% of their patients themselves. The earlier used immune therapies (IFN, IL-2) no longer play a role. Sunitinib is used most often in first-line therapy by urologists in private practice (50.4%) and oncologists in private practice (47.1%). In second- and third-line therapy everolimus is used by urologists in private practice (27.1%, 26.3%) and sorafenib (28.6%) or everolimus (26.4%) by oncologists in private practice. Hospital oncologists use primarily sunitinib (56.1%), in second-line sorafenib (45.5%) and in third-line above all everolimus (19.4%). Hospital urologists use sunitinib most often for first-line therapy (57.6%) and sorafenib for second-line treatment (37.3%), while in third-line therapy temsirolimus (49.6%) and also everolimus (30.4%) were used.

CONCLUSIONS

The therapy of mRCC is determined very strongly by the substances sunitinib and sorafenib. The mTOR inhibitors have recently been increasingly included in the second- and third-line therapy. With the introduction of the new targeted therapies, the treatment of these special patients is performed less by urologists and increasingly more by oncologists. This trend is strengthened in comparison to the DGFIT study from 2008.

Safety and treatment patterns of angiogenesis inhibitors in patients with metastatic renal cell carcinoma: evidence from US community oncology clinics

Safety and treatment patterns of sunitinib and sorafenib in metastatic renal cell carcinoma (mRCC) had been previously reported using retrospective chart review of patients treated in US tertiary centers. Because practice patterns may vary between hospital- and office-based settings, this study examined safety and treatment patterns of these agents in US community oncology clinics. Medical records were retrospectively reviewed for 250 patients with mRCC treated at 18 community oncology clinics. Eligible patients were ≥18 years old and received ≥1 prescription for sunitinib (n = 131) or sorafenib (n = 119) as first-line anti-angiogenic treatment. Rates of adverse events (AEs) and treatment modifications were analyzed; reasons for treatment modifications were examined. Median duration of first-line sunitinib and sorafenib treatment was 5.9 and 5.5 months, respectively. Among patients treated with sunitinib and sorafenib, 86% (30%) and 87% (28%), respectively, experienced ≥1 all-grade (grade 3/4) AE. The most common AEs were fatigue/weakness in sunitinib (all-grade: 42%; grade 3/4: 5%) and skin rash in sorafenib (all-grade: 35%; grade 3/4: 6%). Sixty-two and 64% of patients treated with sunitinib and sorafenib, respectively, had ≥1 treatment modification due to AEs. Recorded AE rates in patients with mRCC treated with angiogenesis inhibitors in community practice tended to be lower than in tertiary centers, possibly due to shorter treatment duration. Rates of treatment modifications due to AEs tended to be higher in community practice. This study provides evidence from an office-based setting of unmet need for agents that may provide improved tolerability in mRCC.

A cost-effectiveness analysis of sunitinib in patients with metastatic renal cell carcinoma intolerant to or experiencing disease progression on immunotherapy: perspective of the Spanish National Health System

AIM

To investigate the cost-effectiveness of sunitinib (50 mg/day, schedule 4/2) vs. best supportive care (BSC) in patients with cytokine-refractory metastatic renal cell carcinoma (mRCC), from the perspective of the Spanish National Health Service.

MATERIAL AND METHODS

A Markov model compared the cost-effectiveness (taking into account drugs; medical visits; laboratory tests; X-rays; terminal care; adverse event management) of sunitinib and BSC across three disease states: no progression, survival with progression and death from mRCC or other causes.

RESULTS

The monthly incremental cost-effectiveness ratio (ICER) values for sunitinib treatment were €6073/progression-free survival month, €25,199/life years and €34,196/quality-adjusted life years (QALY) gained. In 95% of cases, the ICER/QALY values were below the accepted €45,000/QALY threshold. Efficacy and cost of sunitinib had the greatest impact on cost-effectiveness.

CONCLUSION

Sunitinib has a good cost-effectiveness profile in mRCC. The cost per life year and QALY gained is affordable according to current effectiveness thresholds in developed countries.

Update on vaccine development for renal cell cancer

Renal cell carcinoma (RCC) remains a significant health concern that frequently presents as metastatic disease at the time of initial diagnosis. Current first-line therapeutics for the advanced-stage RCC include antiangiogenic drugs that have yielded high rates of objective clinical response; however, these tend to be transient in nature, with many patients becoming refractory to chronic treatment with these agents. Adjuvant immunotherapies remain viable candidates to sustain disease-free and overall patient survival. In particular, vaccines designed to optimize the activation, maintenance, and recruitment of specific immunity within or into the tumor site continue to evolve. Based on the integration of increasingly refined immunomonitoring systems in both translational models and clinical trials, allowing for the improved understanding of treatment mechanism(s) of action, further refined (combinational) vaccine protocols are currently being developed and evaluated. This review provides a brief history of RCC vaccine development, discusses the successes and limitations in such approaches, and provides a rationale for developing combinational vaccine approaches that may provide improved clinical benefits to patients with RCC.

Efficacy of targeted therapy in patients with renal cell carcinoma with pre-existing or new bone metastases

INTRODUCTION

This single-centre retrospective analysis of data from three randomised studies and two expanded-access studies compared the effect of interferon (IFN)-alfa, sunitinib, and sorafenib on the occurrence and progression of metastatic bone lesions in patients with renal cell carcinoma (RCC).

METHODS

The analysis included 292 patients: 107 received sunitinib 50 mg/day in 6-week cycles (Schedule 4/2), 147 received sorafenib 800 mg/day, and 38 received placebo or IFN-alfa 9 MU t.i.w.

RESULTS

Pre-existing metastatic bone lesions were reported in 82 patients, of which 30 experienced progression. Twenty-three of 210 patients developed new bone lesions. Overall, sunitinib appeared slightly more effective than sorafenib or IFN-alfa at extending mean time to progression of pre-existing bone lesions (P = 0.057). Compared with sorafenib, sunitinib significantly decreased formation (P = 0.034) and prolonged time to occurrence of new bone lesions (P = 0.047).

CONCLUSION

Further evaluation of the effect of these therapies on bone metastases in RCC is warranted.

Update on systemic therapies of metastatic renal cell carcinoma

PURPOSE

Recent advances in understanding the molecular biology of advanced and metastatic renal cell carcinoma (RCC) have led to the development of several targeted agents that show impressive antitumor efficacy. The integration of these drugs into clinical practice has revolutionized the therapeutic management of RCC.

METHODS

We reviewed data on all approved targeted agents in the first-line and second-line setting, as well as, studies involving sequential therapy. Data from phase III trials are discussed, and an optional therapeutic algorithm is presented.

RESULTS

Sunitinib should be used as the first-line treatment of choice for good- and intermediate-risk patients according to Memorial Sloan-Kettering Cancer Center (MSKCC) criteria, whereas temsirolimus is recommended for the poor-risk group. The combination of bevacizumab and INF-alpha can be regarded as an alternative to sunitinib. After cytokine failure, patients should be recommended to sorafenib. Everolimus must be considered after first-line failure of a tyrosine kinase inhibitor (TKI); furthermore, recent evidence suggests sequential use of TKIs before administration of everolimus.

CONCLUSIONS

A range of potent drugs are available to patients with metastatic RCC. Treatment decisions should be made carefully taking into consideration that all targeted agents only have a palliative effect with prolongation of life, but do not cure metastatic RCC.

Patient-derived renal cell carcinoma cells fused with allogeneic dendritic cells elicit anti-tumor activity: in vitro results and clinical responses

Renal cell carcinoma (RCC) has been shown to be susceptible to immunotherapeutic treatment strategies. In the present study, patient-derived tumor cells were fused with allogeneic dendritic cells (DC) to elicit anti-tumor activity against RCC. DC from HLA-A2+ healthy donors were fused with primary RCC cells from ten patients. Phenotype of fusion cells were characterized by flow cytometer and confocal microscopy. In vitro, T cell proliferation, IFN-gamma secretion and cytotoxic T lymphocytes (CTL) activity elicited by allogeneic DC/RCC fusion cells were assessed. Clinically, ten patients were vaccinated with allogeneic DC/RCC fusion vaccine. The adverse effects and toxicity were observed. The clinical response was evaluated by CT scans. After fusion, the created hybrids expressed both tumor associated antigen and DC-derived molecules and could stimulate the proliferation and IFN-gamma secretion of T cells as well as elicit strong CTL activity against RCC cells in vitro. In vivo, no serious adverse effects, toxicity, or signs of autoimmune disease were observed after vaccination therapy. Percentage of T lymphocyte subsets in peripheral blood of patients was increased significantly. One of ten patients exhibited a partial response with regression of lung metastases. Six patients showed stable disease with stabilization of previously progressive disease (follow up 1.5 years). The PR and SD responses, exhibited by 7/10 patients who received the allogeneic DC/RCC fusion vaccine treatment, suggest that this approach is safe and can elicit immunological responses in a significant portion of patients with RCC.

YC-1 induces apoptosis of human renal carcinoma A498 cells in vitro and in vivo through activation of the JNK pathway

BACKGROUND AND PURPOSE

The aim of this study was to elucidate the mechanism of YC-1{3-(5'-hydroxy methyl-2'-furyl)-1-benzylindazole}-induced human renal carcinoma cells apoptosis and to evaluate the potency of YC-1 in models of tumour growth in mice.

EXPERIMENTAL APPROACH

YC-1-mediated apoptosis was assessed by analysis of MTT, SRB, DAPI staining and flow cytometry analysis. Knockdown of JNK protein was achieved by transient transfection using siRNA. The mechanisms of action of YC-1 on different signalling pathways involved were studied using western blot. Fas clustering was analysed by confocal microscopy and in vivo efficacy was examined in a A498 xenograft model.

KEY RESULTS

YC-1 displayed cytotoxicity in renal carcinoma cells at 10(-7)-10(-8) M. Increased condensation of chromatin was observed and an increase in the cell population in subG1 phase. Moreover, YC-1 triggered mitochondria-mediated and caspase-dependent pathways. YC-1 significantly induced Fas ligand expression, but did not modify either the protein levels of death receptors or ligands. In addition, Fas clustering in cells responsive to YC-1 was observed, suggesting involvement of a Fas-mediated pathway. Furthermore, YC-1 markedly induced phosphorylation of JNK and a JNK inhibitor, SP600125, and siRNA JNK1/2 significantly reversed YC-1-induced cytotoxicity and protein expression. We suggest that YC-1 induced JNK phosphorylation, the upregulation of FasL and Fas receptor clustering to promote the activation of caspases 8 and 3, resulting in apoptosis. Finally, we demonstrated the antitumour effect of YC-1 in vivo.

CONCLUSIONS AND IMPLICATIONS

These data suggest that YC-1 is a good candidate for development as an anticancer drug.

Lapatinib versus hormone therapy in patients with advanced renal cell carcinoma: a randomized phase III clinical trial

PURPOSE

Lapatinib is an orally reversible inhibitor of epidermal growth factor receptor (EGFR)/human epidermal growth factor receptor 2 (HER-2) tyrosine kinases with demonstrated activity in patients with HER-2-positive breast cancer. In the current phase III open-label trial, lapatinib was compared with hormone therapy (HT) in patients with advanced renal cell carcinoma (RCC) that express EGFR and/or HER-2.

PATIENTS AND METHODS

Patients with advanced RCC who had experienced disease progression through first-line cytokine therapy--stratified by Karnofsky performance status and number of metastatic sites--were randomly assigned to lapatinib 1,250 mg daily or HT. The primary end point was time to progression (TTP); secondary end points included overall survival (OS), safety, and biomarker analyses.

RESULTS

Four hundred sixteen patients were enrolled onto the study. Median TTP was 15.3 weeks for lapatinib versus 15.4 weeks for HT (hazard ratio [HR] = 0.94; P = .60), and median OS was 46.9 weeks for lapatinib versus 43.1 weeks for HT (HR = 0.88; P = .29). In a biomarker analysis of patients with EGFR-overexpressed tumors (3+ by immunohistochemistry [IHC]; n = 241) median TTP was 15.1 weeks for lapatinib versus 10.9 weeks for HT (HR = 0.76; P = .06), and median OS was 46.0 weeks for lapatinib versus 37.9 weeks for HT (HR = 0.69; P = .02). These results were confirmed by Cox regression analysis. No unexpected toxicities were observed; the most commonly reported drug-related adverse events (all grades) for lapatinib were rash (44%) and diarrhea (40%).

CONCLUSION

Lapatinib was well tolerated with equivalent overall efficacy to HT in advanced RCC patients who had experienced disease progression while receiving cytokines, and the study supports that lapatinib prolonged OS relative to HT in patients with 3+ EGFR status determined by IHC.

Sunitinib: a novel tyrosine kinase inhibitor. A brief review of its therapeutic potential in the treatment of renal carcinoma and gastrointestinal stromal tumors (GIST)

Sunitinib malate is a novel oral multitargeted tyrosine kinase inhibitor with antitumor and antiangiogenic activities. Sunitinib was recently approved in first-line treatment for patients with advanced renal cell carcinoma (RCC) and for the treatment of patients with gastrointestinal stromal tumors (GIST) after disease progression or intolerance to imatinib mesylate therapy. We report the very interesting results of the phase II trials after cytokin failure and of the randomized recent trial of sunitinib versus cytokin-based therapy in first-line treatment for patients with metastatic RCC, as well as the promising results of the recent trials on patients with GIST after disease progression or intolerance to imatinib mesylate therapy. Oral sunitinib demonstrates a high level of efficacy with acceptable tolerability with the 50 mg daily for 4 weeks followed by 2 weeks off schedule; a continuous schedule could be of interest. Hypertension and asthenia are the most common side effects with sunitinib. Regardless of these encouraging results, studies investigating sunitinib in first-line treatment (for patients with GIST), adjuvant and neoadjuvant settings are awaited, as well as trials using sunitinb in combination with chemotherapy or other targeted therapies. Clinical trials investigating sunitinib in other tumor types are ongoing.

Immunotherapy of renal cell carcinoma

Carcinomas of the kidney generally have a poor prognosis and respond minimally to classical radiotherapy or chemotherapy. Immunotherapy constitutes an interesting alternative to these established forms of treatment, and indeed, cytokine-based therapies have been used for many years, leading to favorable clinical responses in a small subset of patients. During the past few years, immunotherapeutical trials targeting renal cell tumor-associated antigens have also been reported, with diverse passive or active approaches using antibodies or aimed at activating tumor-directed T lymphocytes. The following review presents the results and the progress made in the field, including classical cytokine treatments, non-myeloablative stem cell transplantation and antigen specific-based trials, with special focus on T-cell studies. In consideration of the few specific molecular targets described so far for this tumor entity, current strategies which can lead to the identification of new relevant antigens will be discussed. Hopefully these will very soon contribute to an improvement in renal cell carcinoma specific immunotherapy and its evaluation.

Sunitinib malate for the treatment of solid tumours: a review of current clinical data

Receptor tyrosine kinases (RTKs) play important roles in the regulation of cellular growth, and mutated or overexpressed RTKs have been implicated in various human cancers. Sunitinib malate is an oral multitargeted tyrosine kinase inhibitor with antitumour and antiangiogenic activity that recently received approval from the FDA for the treatment of advanced renal cell carcinoma and of gastrointestinal stromal tumours after disease progression on or intolerance to imatinib mesilate therapy. Sunitinib has also demonstrated promising clinical activity in the treatment of other advanced solid tumours. The present review provides an updated summary of emerging clinical experience with this promising new anticancer agent.