Closing faucets: the role of anti-angiogenic therapies in malignant pleural diseases

Malignant pleural effusion (MPE) represents 15-35 % of pleural effusions and markedly worsens the prognosis and quality of life of patients with cancer. Malignant mesothelioma (MM) and lung adenocarcinoma are the most frequent primary and secondary causes, respectively, of MPE. Effective treatments for cancer-related MPE are warranted in order to improve symptoms, reduce the number of invasive pleural procedures, and prolong patient life. Since angiogenesis plays a key role in MPE development, the potential role of bevacizumab and other anti-angiogenic therapies have been explored in this review. No relevant phase III trials have specifically analysed the benefit from adding bevacizumab to platinum-based chemotherapy in lung cancer-related MPE. However, small retrospective series reported 71.4-93.3 % MPE control rate, a reduction in invasive procedures, and a safe profile with this combination. Being approved for the first-line treatment of non-squamous advanced NSCLC, the addition of bevacizumab should be considered for patients presenting with MPE. In addition, further studies in this are recommended. In MM, the addition of bevacizumab to platinum-based chemotherapy did not meet primary endpoints in two phase II trials. However, the beneficial results on OS reported in comparison with historical cohorts and the statistically significant benefit on PFS and OS observed in the phase III MAPS trial foretell an eventual role for the combination of platinum/pemetrexed/bevacizumab as front-line systemic therapy for pleural MM. To date, no other anti-angiogenic drug has showed significant benefit in the treatment of patients with either MPE or MM. However, new promising drugs such as ramucirumab or recombinant human endostar warrant further investigation.

Risk of serious neutropenic events in cancer patients treated with bevacizumab: a meta-analysis

Bevacizumab has been approved for use in combination with chemotherapy to treat many types of cancer but associated neutropenic events, including febrile neutropenia, have been reported. To estimate the incidence and relative risk of neutropenic events in cancer patients treated with bevacizumab combination therapy, we searched PubMed, EMBASE, and Web of Science literature databases, as well as abstracts presented at the American Society of Clinical Oncology conferences, to identify relevant studies published from January 1966 to December 2011. Studies that compared bevacizumab plus chemotherapy or biological therapy with chemotherapy or biological therapy alone, and that had adequate safety data profiles, were selected for analysis. Statistical analyses were conducted to calculate the summary incidence rates, relative risks (RRs), and 95% confidence intervals (CIs) using fixed- or random-effects models. A total of 22 clinical trials involving 15,056 patients were included in the analysis. The summary incidences of high-grade neutropenia (HGN) and high-grade febrile neutropenia (HGFN) in patients receiving bevacizumab was 27.3% (95% CI: 26.4%-28.3%) and 3.91% (95% CI: 3.51%-4.37%), respectively. The risks of HGN (RR=1.10; 95% CI: 1.02-1.19; P=0.02) and HGFN (RR=1.31; 95% CI: 1.08-1.59; P=0.005) were significantly increased in bevacizumab-treated patients, compared to those who did not receive bevacizumab. The RR of bevacizumab-associated HGN, but not HGFN, varied significantly with tumor types (P=0.005). The increased risk of bevacizumab-associated neutropenic events was dose-dependent, as the RR was greater at a dose of 5 mg/kg/week than at 2.5 mg/kg/week. Our findings suggest that bevacizumab addition to cancer therapy significantly increases the risk of serious neutropenic events, and this risk may be dose-dependent.

Recombinant human endostatin (endostar) decreased recurrent ascites, pleural fluid and ascitic VEGF in a case of advanced mesothelioma

We report a case of 43-year-old male with advanced malignant mesothelioma (MM) with a large amount of fluid in the pleural and peritoneal cavity. The addition of endostar to the gemcitabine-cisplatin regimen gave a prompt and significant improvement of clinical symptoms and disappearance of ascites. The patient is still progression free after 27 months. Endostar, in combination with chemotherapy should be explored in the treatment of MM, especially its effect on pleural and ascitic fluid.

SU6668, a multiple tyrosine kinase inhibitor, inhibits progression of human malignant pleural mesothelioma in an orthotopic model

BACKGROUND AND OBJECTIVE

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm of the mesothelium with high chemotherapeutic resistance. In this study, the preclinical therapeutic activity of the multiple tyrosine kinase inhibitor, SU6668, against MPM was examined.

METHODS

Two human MPM cell lines with different pro-angiogenic cytokine expression, Y-MESO-14 cells that express high levels of vascular endothelial growth factor (VEGF) and MSTO-211H cells that express high levels of basic fibroblast growth factor (bFGF), were orthotopically inoculated into the thoracic cavities of mice with severe combined immunodeficiency. The mice with MPM were treated or not treated with SU6668 (200 mg/kg/day).

RESULTS

SU6668 abrogated the proliferation of endothelial cells stimulated by VEGF or bFGF, but did not directly affect the growth of human MPM cells in vitro. In this orthotopic implantation model, treatment with SU6668 effectively reduced tumour weight and pleural effusion volumes, in association with inhibition of the growth of tumour vasculature. More importantly, treatment with SU6668 significantly prolonged survival time in mice with MPM.

CONCLUSIONS

These findings suggest that SU6668 has a promising therapeutic effect on the progression of MPM in vivo through its anti-angiogenic effects.

Molecular pathogenesis of malignant mesothelioma

Malignant mesothelioma is a rare, highly aggressive cancer arising from mesothelial cells that line the pleural cavities. Approximately 80% of mesothelioma cases can be directly attributed to asbestos exposure. Additional suspected causes or co-carcinogens include other mineral fibres, simian virus 40 (SV40) and radiation. A mesothelioma epidemic in Turkey has demonstrated a probable genetic predisposition to mineral fibre carcinogenesis and studies of human tissues and animal models of mesothelioma have demonstrated genetic and epigenetic events that contribute to the multistep process of mineral fibre carcinogenesis. Several growth factors and their receptors have a significant role in the oncogenesis, progression and resistance to therapy of mesothelioma. Epidermal growth factor (EGF), hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF) and insulin-like growth factor (IGF) have been shown as targets for therapy based on promising preclinical data. However, clinical trials of tyrosine kinase inhibitors in mesothelioma have been disappointing. Bcl-XL is an important antiapoptotic member of the Bcl-2 family and is overexpressed in several solid tumours, including mesothelioma. Reduction of Bcl-XL expression in mesothelioma induces apoptosis and engenders sensitisation to cytotoxic chemotherapeutic agents. Pharmacological inhibitors of antiapoptotic Bcl-2 family members continue to undergo refinement and have shown promise in mesothelioma.

Systemic treatment of malignant pleural mesothelioma

Malignant pleural mesothelioma is a rare malignancy with a dismal prognosis. The clinical management of most of the patients with this disease is quite challenging, and, overall, the therapeutic strategy has not yet benefited from the recent advances in molecular biology. Randomized evidence supports the use of cisplatin in combination with pemetrexed or raltitrexed as first-line treatments. In elderly patients with comorbidities cisplatin may be replaced by carboplatin because of a lesser burden of toxicities. The role of second-line chemotherapy is unproven, although pemetrexed can be regarded as the standard option in pemetrexed-naive patients and therapeutic rechallenge with pemetrexed may be considered in selected patients with prolonged disease control after first-line therapy. Targeted therapies failed to demonstrate any substantial activity; however, immunotherapies may complement other treatment strategies. In summary, there is an unmet clinical need and innovative approaches to select new potentially active drugs are highly warranted.

[Anti-angiogenic factors in thoracic oncology: successes, failures and prospects]

Many growth factors involved in tumor angiogenesis are potential targets in thoracic oncology. This work is a review of the literature on the effectiveness of anti-angiogenic treatments in non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC) and malignant pleural mesothelioma (MM). Thirty-four articles and 15 abstracts were identified. Currently, bevacizumab is the only drug that has demonstrated an impact on overall survival in first line treatment for stage IV non-squamous NSCLC, but VEGFR-TKI such as cediranib, aflibercept, vandetanib, pazopanib have shown encouraging results in phase II or III clinical trials. In extensive-disease SCLC and inoperable MM, bevacizumab is the most studied molecule, but again, clinical trials are still ongoing. Current data on potential predictors for efficacy are disappointing, but some biomarkers or radiological techniques might be useful for guiding the use of anti-angiogenic therapies in the future. In conclusion, bevacizumab is the most studied anti-angiogenic agent in thoracic oncology. It is the only approved drug with an indication in first-line and maintenance treatment for stage IV non-squamous NSCLC. The indications for the use of VEGFR-TKI in clinical practice remain to be defined.

Phase II study of cediranib in patients with malignant pleural mesothelioma: SWOG S0509

INTRODUCTION

Malignant pleural mesothelioma (MPM) tumors express vascular epithelial growth factor (VEGF) and VEGF receptors. We conducted a phase II study of the oral pan-VEGF receptor tyrosine kinase inhibitor, cediranib, in patients with MPM after platinum-based systemic chemotherapy.

METHODS

Patients with MPM previously treated with a platinum-containing chemotherapy regimen and a performance status 0 to 2 were eligible for enrollment. Cediranib 45 mg/d was administered until progression or unacceptable toxicity. The primary end point was response rate. Tumor measurements were made by RECIST criteria, with a subset analysis conducted using modified RECIST. A two-stage design with an early stopping rule based on response rate was used.

RESULTS

Fifty-four patients were enrolled. Of 47 evaluable patients, 4 patients (9%) had objective responses, 16 patients (34%) had stable disease, 20 patients (43%) had disease progression, 2 patients (4%) had symptomatic deterioration, and 1 patient (2%) had early death. The most common toxicities were fatigue (64%), diarrhea (64%), and hypertension (70%); 91% of patients required a dose reduction. Median overall survival was 9.5 months, 1-year survival was 36%, and median progression-free survival was 2.6 months.

CONCLUSION

Cediranib monotherapy has modest single-agent activity in MPM after platinum-based therapy. However, some patient tumors were highly sensitive to cediranib. This study provides a rationale for further testing of cediranib plus chemotherapy in MPM and highlights the need to identify a predictive biomarker for cediranib.

Preclinical emergence of vandetanib as a potent antitumour agent in mesothelioma: molecular mechanisms underlying its synergistic interaction with pemetrexed and carboplatin

Background:

Although pemetrexed, a potent thymidylate synthase (TS) inhibitor, enhances the cytoytoxic effect of platinum compounds against malignant pleural mesothelioma (MPM), novel combinations with effective targeted therapies are warranted. To this end, the current study evaluates new targeted agents and their pharmacological interaction with carboplatin–pemetrexed in human MPM cell lines.

Methods:

We treated H2052, H2452, H28 and MSTO-211H cells with carboplatin, pemetrexed and targeted compounds (gefitinib, erlotinib, sorafenib, vandetanib, enzastaurin and ZM447439) and evaluated the modulation of pivotal pathways in drug activity and cancer cell proliferation.

Results:

Vandetanib emerged as the compound with the most potent cytotoxic activity, which interacted synergistically with carboplatin and pemetrexed. Drug combinations blocked Akt phosphorylation and increased apoptosis. Vandetanib significantly downregulated epidermal growth factor receptor (EGFR)/Erk/Akt phosphorylation as well as E2F-1 mRNA and TS mRNA/protein levels. Moreover, pemetrexed decreased Akt phosphorylation and expression of DNA repair genes. Finally, most MPM samples displayed detectable levels of EGFR and TS, the variability of which could be used for patients’ stratification in future trials with vandetanib–pemetrexed–carboplatin combination.

Conclusion:

Vandetanib markedly enhances pemetrexed–carboplatin activity against human MPM cells. Induction of apoptosis, modulation of EGFR/Akt/Erk phosphorylation and expression of key determinants for pemetrexed and carboplatin activity contribute to this synergistic interaction, and, together with the expression of these determinants in MPM samples, warrant further clinical investigation.

Anti-vascular endothelial growth factor antibody bevacizumab reduced the risk of anemia associated with chemotherapy-A meta-analysis

INTRODUCTION

Vascular endothelial growth factor (VEGF) may play a role in erythropoiesis. We performed a meta-analysis of randomized controlled trials (RCT) to determine the effect of the anti-VEGF antibody bevacizumab on anemia in cancer patients treated with chemotherapy.

METHODS

Databases from PUBMED, the Web of Science, Embase, the Cochrane Library, and abstracts presented at the American Society of Clinical Oncology (ASCO) conferences until May 2010 were searched to identify relevant studies. Eligible studies included prospective RCTs in which the combination of bevacizumab and chemotherapy was compared with chemotherapy alone. Summary incidence rate, relative risk (RR), and 95% confidence interval (CI) were calculated.

RESULTS

A total of 6439 patients with a variety of solid tumors were included for analysis from 11 RCTs. Among those patients receiving bevacizumab and chemotherapy, the incidences of all-grade and high-grade (grade 3 and above) anemia were 17.8% (95% CI: 11.1-27.1%) and 2.8% (95% CI: 1.6-5.0%) respectively. In comparison with chemotherapy alone, bevacizumab significantly reduced all-grade (RR, 0.79; 95% CI: 0.66-1.0, p = 0.007) and high-grade anemia (RR, 0.72; 95% CI: 0.57-0.90, p = 0.005). The effect did not vary significantly among bevacizumab doses (p = 0.88), tumor types (p = 0.75) or chemotherapy regimens (p = 0.98).

DISCUSSION

Bevacizumab may significantly reduce the risk of anemia with chemotherapy in cancer patients.

Malignant mesothelioma

Malignant mesothelioma (MM) is an aggressive tumour that commonly affects the mesothelial surfaces of the pleural and peritoneal cavities, and occasionally, the tunica vaginalis and the pericardium. Formerly a rare tumour, MM is increasing in incidence in Australia due to the heavy nationwide use of asbestos from 1940 until the 1980s. The incidence is expected to peak in Australia in the next decade, mirroring the long latency period between asbestos exposure and development of MM. Diagnosis of MM can be difficult. Definitive pathological diagnosis is required and it often requires an experienced pathologist to differentiate MM from other benign or malignant processes. Treatment of MM requires a multidisciplinary approach, regardless of palliative or curative intent. Treatment options, such as surgery, chemotherapy, radiotherapy and active symptom control or a combination of these, may be used. Further research is needed to advance the therapeutic options for MM, and strategies to realize personalisation of therapy through discovery of predictive markers. In the Australian society where asbestos contamination of the built environment is very high, education and stringent public health measures are required to prevent a second wave of increased MM incidence.

Novel targeted therapies and vaccination strategies for mesothelioma

Novel targeted therapies have found a niche in the treatment of many cancers, although the most responsive populations, best biomarkers of response, and appropriate treatment settings are still under investigation. With few exceptions, cancer vaccination strategies have not entered into routine management. In malignant mesothelioma, combination first-line chemotherapy with a platinum and pemetrexed remains the standard of care when systemic therapy is considered. Second-line chemotherapy is used but benefits are uncertain in the absence of appropriately controlled randomized trials. Currently, there are no novel targeted therapies or vaccinations that should be used in this disease outside the context of a clinical trial.

Chemotherapy and targeted therapies for unresectable malignant mesothelioma

The global burden of mesothelioma is expected to increase in the coming decades. As a result the development of more effective therapies with an emphasis on personalized treatments based on validated prognostic and predictive biomarkers is an essential requirement. Progress has been made in the last decade with the development of newer generation anti-folates leading to the current standard of care of pemetrexed and cisplatin in patients with unresectable disease. However, the median overall survival of patients with this combination treatment is only 12 months. There is no consensus regarding second line therapy for patients who have progressed or not responded to pemetrexed based therapies although gemcitabine in combination with a platinum compound or single agent vinorelbine is a reasonable option. The development of effective targeted agents that are active in mesothelioma has to date been disappointing. Strategies involving the addition of bevacizumab to pemetrexed and cisplatin in the frontline setting, the histone deacetylase inhibitor vorinostat as second line therapy and studies evaluating the utility of maintenance therapy in mesothelioma are all ongoing and appear promising. In addition clinical trials investigating immunotherapy and gene therapy in combination with chemotherapy could potentially improve the prognosis of patients with mesothelioma.

Combined chemotherapy with cytotoxic and targeted compounds for the management of human malignant pleural mesothelioma

Human malignant pleural mesothelioma (hMPM) is an aggressive asbestos-associated cancer, the incidence of which is increasing and which, despite progress in diagnosis and therapy, continues to have a poor prognosis. Asbestos fibers induce aberrant cell signaling, leading to proto-oncogene activation and chemoresistance. In this review, we discuss the evolution of pharmacological management of hMPM up to the most recent advances. Monotherapy with single cytotoxic drugs achieves modest objective response rates, seldom reaching 30%. However, combination regimens using novel drugs and standard molecules are showing gradually improving responses and clinical benefits. Phase II/III studies have identified pemetrexed, a multitarget folate pathway inhibitor in combination with platinum derivatives, and the cisplatin/gemcitabine association as front-line chemotherapy for hMPM. Detailed knowledge of molecular mechanisms of signal transduction and neoangiogenesis in hMPM should aid in the design and screening of other promising compounds such as more efficacious receptor tyrosine kinase inhibitors.

Advances in the biology of malignant pleural mesothelioma

Malignant pleural mesothelioma is a highly aggressive cancer with a very poor prognosis. Although the mechanism of carcinogenesis is not fully understood, approximately 80% of malignant pleural mesothelioma can be attributed to asbestos fiber exposure. This disease is largely unresponsive to conventional chemotherapy or radiotherapy, and most patients die within 10-17 months of their first symptoms. Currently, malignant pleural mesothelioma therapy is guided by clinical stage and patient characteristics rather than by the histological or molecular features of the tumor. Several molecular pathways involved in malignant pleural mesothelioma have been identified; these include cell cycle regulation, apoptosis, growth factor pathways, and angiogenesis. Unfortunately, several agents targeting these processes, including erlotinib, gefitinib, and imatinib, have proven ineffective in clinical trials. A greater understanding of the molecular pathways involved in malignant pleural mesothelioma is needed to develop better diagnostics, therapeutics, and preventative measures. Moreover, understanding the biological basis of mesothelioma progression may facilitate personalized treatment approaches, and early identification of poor prognostic indicators may help reduce the heterogeneity of the clinical response. This paper reviews advances in the molecular biology of malignant pleural mesothelioma in terms of pathogenesis, the major molecular pathways and the associated therapeutic strategies, and the roles of biomarkers.

Bevacizumab increases the risk of arterial ischemia: a large study in cancer patients with a focus on different subgroup outcomes

BACKGROUND

Bevacizumab, a humanized monoclonal antibody targeting the vascular endothelial growth factor, is a therapeutic agent used in a variety of neoplasms. We did a meta-analysis of randomized controlled trials to fully characterize the arterial thromboembolic events (ATEs) risk with bevacizumab in certain patients' subgroups.

MATERIALS AND METHODS

We carried out a literature search on Medline for randomized trial reported from January 1966 to December 2009. Abstracts presented at the American Society of Clinical Oncology held between 2004 and 2009 were also searched for relevant clinical trials. Summary incidence, relative risks (RRs) and 95% confidence intervals (CIs) were calculated using random-effects or fixed-effects models based on the heterogeneity of included studies.

RESULTS

A total of 13,026 patients from 20 randomized trials were included in the meta-analysis. Overall RR for ATE with bevacizumab-based therapy versus controls was 1.46 (95% CI 1.11-1.93, P = 0.007). On subgroup analysis, no significant risk differences were found based on the type of malignancy, type of clinical trial (phase II or III trials), type of publication (full papers versus presentations), high- versus low-dose bevacizumab and early versus advanced disease trials. When stratified by concomitant therapies, we found that gemcitabine-based regimens had a significant lower ATE risk compared with non-gemcitabine regimens (P = 0.01).

CONCLUSIONS

Bevacizumab treatment is associated with a significant increase in the risk of arterial thrombosis. Our results seem to be generalizable to the vast majority of patients receiving bevacizumab in multiple settings.

An Unusually Large Pleural Mesothelioma with an Outstanding Clinical Response and Long Lasting Survival: A Case Report and Literature Review

Malignant pleural mesothelioma is a neoplasm characterized by an increasing incidence and poor prognosis. When surgical treatment cannot be performed, systemic chemotherapy remains the main therapeutic option. Here we report the case of a 41-year-old female patient with epithelioid malignant pleural mesothelioma who was treated with carboplatin and pemetrexed despite her critical condition. She showed an impressive response to this first-line chemotherapy and, after disease progression, to further chemotherapy with gemcitabine and vinorelbine. She is still alive, with unexpectedly long-lasting survival. Free full text available at www.tumorionline.it

Incidence and risk of significantly raised blood pressure in cancer patients treated with bevacizumab: an updated meta-analysis

PURPOSE

Bevacizumab is a humanized monoclonal antibody targeting vascular endothelial growth factor. The aim of this study was to gain a better understanding of the overall incidence and risk of significantly raised blood pressure in cancer patients who receive bevacizumab therapy.

METHODS

We performed a meta-analysis of relevant randomized controlled trials (RCTs) identified in PubMed, Cochrane library, Embase, and American Society of Clinical Oncology conferences. Overall incidence rates, relative risks (RRs), and 95% confidence intervals (CIs) were calculated using a random-effects model. The primary clinical endpoint was significantly raised blood pressure (grade 3 or above).

RESULTS

A total of 12,949 cancer patients with a variety of solid tumors from 19 RCTs were included in our meta-analysis. The overall incidence of significantly raised blood pressure was 8% (95% CI 6-10%) among patients receiving bevacizumab. Bevacizumab treatment was associated with a statistically significant increased risk of developing significantly raised blood pressure (RR 5.38, 95% CI 3.63-7.97). The RRs of significantly raised blood pressure in patients receiving bevacizumab at 5 and 2.5 mg/kg per week were 7.17 (95% CI, 3.91-13.13) and 4.11 (95% CI 2.49-6.78), respectively. Among cancer patients, those with renal cell carcinoma (RR 13.77, 95% CI 2.28-83.15) and breast cancer (RR 18.83, 95% CI 1.23-292.29) who received bevacizumab at 5 mg/kg per week had a higher risk of developing significantly raised blood pressure.

CONCLUSIONS

Among the patients included in the trials analyzed in this meta-analysis, the addition of bevacizumab to cancer therapy treatments significantly increased the risk of significantly raised blood pressure. The risk may be dose-dependent and vary with tumor type.

Malignant peritoneal mesothelioma. Is there a new treatment?

The authors report a novel, alternative approach to treat malignant peritoneal mesothelioma (MPeM) targeting, vascular endothelial growth factor (VEGF) using anti-VEGF (bevacizumab) chemotherapy combination.

Malignant pleural mesothelioma: an update on biomarkers and treatment

Although the insulating properties of asbestos have been known for millennia, the link between asbestos exposure and mesothelioma was not recognized until 1960, when it was first described in South African asbestos miners. The incidence of mesothelioma parallels asbestos usage with a latency of 20 to 40+ years; thus, patient numbers are declining in the United States but rising in the developing world. Radiation, genetics, and possibly simian virus 40 are less common causes. Diagnosis can be challenging, since the results of pleural fluid cytology testing are often negative despite repeated sampling. No staging system adequately predicts prognosis in the unresected patient. Newly described biomarkers, including soluble mesothelin-related peptide, megakaryocyte potentiation factor, and osteopontin, may predict which asbestos-exposed individuals will develop mesothelioma, and may prove useful in assessing response to treatment. Since surgery cannot eradicate all residual microscopic disease, a multimodality approach is encouraged. Metaanalysis suggests that pleurectomy/decortication may achieve outcomes similar to those of extrapleural penumonectomy. The standard first-line chemotherapy for unresectable disease is pemetrexed plus cisplatin. This combination improves response, survival, time to progression, pulmonary function, and disease-related symptoms. Carboplatin is often substituted, with similar results. Other active agents include raltitrexed, gemcitabine, and vinorelbine. Novel agents in clinical trials include inhibitors of the epidermal growth factor receptor, vascular endothelial growth factor, mesothelin, and histone deacetylases. Although disappointing results of early trials did not confirm promising preclinical data, recent studies have suggested that some novel agents may be effective. As we learn more about mesothelioma biology, molecularly targeted agents may become treatment options.

Malignant pleural mesothelioma

Malignant pleural mesothelioma continues to be a challenge. The diagnosis and treatment of patients with malignant pleural mesothelioma requires a multidisciplinary approach. The diagnosis is best made by thoracoscopic biopsy and the aid of immunohistochemistry. Molecular studies identified inactivation of the neurofibromatosis-2 gene and INK4alpha/ARF to be key events in tumorigenesis. Based on the results of a Phase III trial, the combination of cisplatin with pemetrexed has become the preferred choice for chemotherapy, although there is suggestive evidence for the activity of other platin combinations based on Phase II studies. The optimal second-line chemotherapy remains to be defined. Surgical interventions ranging from pleurectomy/decortication to extrapleural pneumonectomy are increasingly offered in specialized centers, and the results of multimodality approaches with neoadjuvant or adjuvant chemotherapy and extrapleural pneumonectomy are encouraging. Ongoing investigations are defining the role of postoperative radiotherapy and the clinical activity of tyrosine kinase inhibitors targeting VEGFR2, histone deacetylase inhibitors and proteosome inhibitors.

Malignant pleural mesothelioma: medical treatment update

Malignant pleural mesothelioma (MPM) is a disease usually unaffected by current therapeutic strategies, but for the majority of patients, the use of systemic chemotherapeutic drugs remains the only therapeutic option available. During the past 15-20 years, many phase II and a few phase III clinical trials have studied a large variety of drugs such as anthracyclines, alkylating agents, platinum compounds, taxanes, vinka alkaloids, and antifolates as single agents and in combination, with the aim to increase responses and survival. The combination of pemetrexed and cisplatin tested in the largest phase III randomized trial of malignant pleural mesothelioma ever conducted has become the current standard of care. New targeted therapeutic approaches with a variety of anti-growth factor drugs are currently undergoing investigation worldwide.

Malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a deadly disease that occurs in 2,000 to 3,000 people each year in the United States. Although MPM is an extremely difficult disease to treat, with the median overall survival ranging between 9 and 17 months regardless of stage, there has been significant progress over the last few years that has reshaped the clinical landscape. This article will provide a comprehensive discussion of the latest developments in the treatment of MPM. We will provide an update of the major clinical trials that impact mesothelioma treatment in the resectable and unresectable settings, discuss the impact of novel therapeutics, and provide perspective on where the clinical research in mesothelioma is moving. In addition, there are controversial issues, such as the role of extrapleural pneumonectomy, adjuvant radiotherapy, and use of intensity-modulated radiotherapy versus hemithoracic therapy that will also be addressed in this manuscript.

Biomarkers for malignant pleural mesothelioma: current status

Malignant pleural mesothelioma (MPM) is an aggressive tumor with poor prognosis, whose main etiology is exposure to asbestos fibers. The incidence of MPM is anticipated to increase worldwide during the first half of this century. For various reasons, MPM is difficult to diagnose and is notoriously refractory to most treatments. However, recently two active chemotherapy regimens have been demonstrated to significantly increase survival in patients with MPM, and several therapeutic agents and strategies are currently under evaluation.Researchers have actively sought MPM biomarkers for more than 20 years. Biomarkers would be helpful in managing three clinical aspects of MPM: early diagnosis, prognosis, and treatment outcome prediction. The aims of the present review are to summarize the published and recently presented data on MPM biomarkers and to identify the prospects for future translational research projects.Among the 'classical' diagnostic biomarkers measured in biological fluids, such as cytokeratins and cell surface antigens, none discriminate patients with MPM from those with other malignancies and nonmalignant diseases. Osteopontin, soluble mesothelin, and megakaryocyte potentiating factor (MPF) appear to be the most promising of the recent biomarkers, but are still subject to some limitations. Osteopontin lacks specificity for mesothelioma, while both soluble mesothelin and MPF lack sensitivity for detecting non-epithelial subtypes. Panels consisting of a small set of biomarkers do not improve the diagnostic yield, and results from molecular profiling are too preliminary to be brought into daily clinical practice. While a large number of biomarkers have been assessed in biological fluids and tumor tissue for their prognostic value, none have had a widespread impact on clinical practice. In contrast, data concerning predictive biomarkers are very limited, even though they are most interesting from the perspective of clinicians.Additional prospective studies, in large and independent samples of patients, with rigorous statistical methodology and standardized laboratory techniques are now warranted to validate and define the precise value of diagnostic and prognostic MPM biomarkers. Future research efforts should focus on biomarkers predictive of the efficacy and toxicity of standard chemotherapy. Translational research should be systematically incorporated into the design of clinical trials assessing new targeted agents in MPM.

Treatment of peritoneal mesothelioma in pediatric patients

Peritoneal mesothelioma is a rare and often aggressive malignancy, mostly affecting asbestos exposed adults. We present four pediatric peritoneal cases treated with a cisplatin-based doublet regimen, the standard of care in the systemic therapy of adult mesothelioma. Treatment was well tolerated, and three of these patients have achieved long-term survival. The fathers of three of the patients worked in the construction industry and may have been the source of indirect asbestos exposure.

Monoclonal antibodies targeting vascular endothelial growth factor: current status and future challenges in cancer therapy

The use of monoclonal antibodies targeting the vascular endothelial growth factor (VEGF) pathway has been a significant addition to cancer therapy. One of the VEGF family members, VEGF-A (commonly referred to as VEGF), has been demonstrated to be important in angiogenesis. Although the mechanism of action of these antibodies is still under study, the anti-VEGF antibody bevacizumab has been approved for treatment of various solid cancers including colorectal, lung, and breast cancers as well as glioblastoma and renal cell carcinoma. Addition of bevacizumab to chemotherapy as adjuvant therapy in colorectal cancer did not improve disease-free survival. Bevacizumab is being tested in other clinical settings such as adjuvant therapy, maintenance therapy, and in combination with both chemotherapy and other targeted agents such as the epidermal growth factor receptor kinase inhibitor erlotinib. In addition to bevacizumab, other antibody-based therapies targeting the VEGF pathway are being tested. Ramucirumab and IMC-18F1 are monoclonal antibodies that target the VEGF receptors VEGFR-2 and VEGFR-1, respectively. Aflibercept (VEGF-Trap), a peptide-antibody fusion targeting VEGF ligand, is being tested in clinical trials. Much research is focused on identifying biomarkers to predict which patients will benefit from anti-VEGF therapy. Recent results suggest that VEGF single nucleotide polymorphisms may be predictive of patient response to bevacizumab. Improved imaging modalities such as dynamic contrast-enhanced MRI (DCE-MRI) can better characterize the efficacy of anti-angiogenic agents. As anti-VEGF treatments such as bevacizumab have been integrated into the treatment of many different types of cancers, the development of bevacizumab-resistant tumors has become more common. Recent studies show that targeting other angiogenesis signaling pathways such as platelet-derived growth factor-C (PDGF-C), Bombina variagata peptide 8 (Bv8, also known as prokineticin-2), and VEGFR-3 may lead to enhanced response in anti-VEGF resistant tumors. In the future, tailored treatments consisting of combinations of chemotherapy, other targeted therapies, and anti-angiogenesis agents will hopefully result in better patient outcomes.

Recent advances in the treatment of malignant pleural mesothelioma

Malignant pleural mesothelioma clinically manifests after decades of initial exposure to etiologic agents, such as asbestos, and presents with nonspecific symptoms such as dyspnea, pain, or weight loss. In patients with limited, resectable disease, surgical therapy with extrapleural pneumonectomy or pleurectomy is recommended, although, it is unclear which approach is superior. Radiation has a limited role and is used primarily for palliation. The palliative efficacy of traditional chemotherapeutic agents and combination regimens is modest at best. The combination of cisplatin and pemetrexed, a novel multitargeted antifolate agent, is the approved "standard of care" for patients with unresectable malignant pleural mesothelioma. A number of molecularly targeted agents are currently under evaluation for mesothelioma such as the Histone deacetylase (HDAC) inhibitors that have demonstrated promising anticancer activity. Vorinostat, a small molecule inhibitor of HDAC, which targets select members of class I and II HDACs, has shown early evidence of activity and is currently being evaluated in a randomized study for patients who progress with standard therapy for advanced mesothelioma. It is hoped that the HDAC inhibitors and other novel targeted agents will pave the way for improved outcomes for patients with this disease.

Erlotinib plus bevacizumab in previously treated patients with malignant pleural mesothelioma

BACKGROUND

We conducted a phase 2, multicenter, open-label study of erlotinib plus bevacizumab in patients with malignant pleural mesothelioma who had previously received 1 prior chemotherapy regimen. These agents have activity in non-small cell lung cancer, but their role in mesothelioma is unclear. The primary endpoint is response rate. Secondary endpoints include time to progression, survival, and toxicity.

METHODS

Eligible patients with mesothelioma who had previously received 1 chemotherapy regimen were treated with erlotinib 150 mg per os daily and bevacizumab 15 mg/kg administered intravenously on Day 1 of a 21-day cycle. Treatment continued until disease progression or development of significant toxicity. Tumor response was assessed after every 2 cycles using previously established mesothelioma response criteria from Byrne and Nowak.

RESULTS

Twenty-four eligible patients initiated therapy with erlotinib and bevacizumab between February 2004 and October 2006. There were no complete or partial responses, although 12 patients achieved stable disease for at least 2 cycles of treatment. The median time to progression was 2.2 months (95% confidence interval [CI], 1.4 months-5.9 months). The median survival was 5.8 months (95% CI, 2.8 months-10.1 months). The most common toxicities were rash and diarrhea. There were no treatment-related deaths, intracranial bleeding, or hemoptysis.

CONCLUSIONS

The combination of erlotinib and bevacizumab was tolerated reasonably well, but there was no evidence of radiographic response. This study demonstrates the feasibility of conducting trials in mesothelioma patients who have failed first-line therapy. More therapeutic studies with effective agents are needed for these patients.

Systemic treatments for mesothelioma: standard and novel

Systemic therapy is the only treatment option for the majority of mesothelioma patients, for whom age, co-morbid medical illnesses, non-epithelial histology, and locally advanced disease often preclude surgery. For many years, chemotherapy had a minimal impact on the natural history of this cancer, engendering considerable nihilism. Countless drugs were evaluated, most of which achieved response rates below 20% and median survival of <1 year. Several factors have hampered the evaluation of systemic regimens in patients with mesothelioma. The disease is uncommon, affecting only about 2500 Americans annually. Thus, most clinical trials are small, and randomized studies are challenging to accrue. There is significant heterogeneity within the patient populations of these small trials, for several reasons. Since all of the staging systems for mesothelioma are surgically based, it is almost impossible to accurately determine the stage of a patient who has not been resected. Patients with very early stage disease may be lumped together with far more advanced patients in the same study. The disease itself is heterogenous, with many different prognostic factors, most notably three pathologic subtypes—epithelial, sarcomatoid, and biphasic—that have different natural histories, and varying responses to treatment. Finally, response assessment is problematic, since pleural-based lesions are difficult to measure accurately and reproducibly. Assessment criteria often vary between trials, making some cross-trial comparisons difficult to interpret. Despite these limitations, in recent years, there has been a surge of optimism regarding systemic treatment of this disease. Several cytotoxic agents have been shown to generate reproducible responses, improve quality of life, or prolong survival in mesothelioma. Drugs with single-agent activity include pemetrexed, raltitrexed, vinorelbine, and vinflunine. The addition of pemetrexed or raltitrexed to cisplatin prolongs survival. The addition of cisplatin to pemetrexed, raltitrexed, gemcitabine, irinotecan, or vinorelbine improves response rate. The combination of pemetrexed plus cisplatin is considered the benchmark front-line regimen for this disease, based on a phase III trial in 456 patients that yielded a response rate of 41% and a median survival of 12.1 months. Vitamin supplementation with folic acid is essential to decrease toxicity, though recent data suggests that there may be an optimum dose of folic acid that should be administered; higher doses may diminish the effectiveness of pemetrexed. There are also several unresolved questions about the duration and timing of treatment with pemetrexed that are the subject of planned clinical trials. It is essential to recognize that the improvements observed with the pemetrexed/cisplatin combination, though real, are still modest. Other active drugs or drug combinations may be more appropriate for specific individuals, and further research is still needed to improve upon these results. Since the majority of mesotheliomas in the United States occur in the elderly, non-cisplatin-containing pemetrexed combinations may be more appropriate for some patients. Now that effective agents have been developed for initial treatment, several classical cytotoxic drugs and many novel agents are being evaluated in the second-line setting. These include drugs targeted against the epidermal growth factor, platelet-derived growth factor, vascular endothelial growth factor, src kinase, histone deacetylase, the proteasome, and mesothelin. Given the progress made in recent years, there is reason to believe that more effective treatments will continue to be developed.

[Malignant pleural mesothelioma: interrogations and hopes concerning the expected epidemic]

Malignant pleural mesothelioma (MPM) is a rare incurable tumor. Interest in MPM has increased in recent years due to a steadily increasing incidence subsequent to the intensive use of asbestosis, the main causal agent, but also due to better awareness in the political and scientific communities faced with a serious public health issue. Our knowledge of MPM has improved regularly in terms of pathologic diagnosis and the mechanisms underlying the mesothelial carcinogenesis. MPM is also the subject of many technological innovations as illustrated by the recent identification of new biological markers, access to metabolic imaging, and clinical research on targeted treatments. Proper management implies the participation of the general population since the implementation of administrative procedures for social indemnities. In 2007, a more aggressive therapeutic approach is becoming common practice with the use of radiotherapy and the emergence of the concept of multimodal care centered on wide pleuropneumonectomy. These advances create real hope for improvement, but also many interrogations since no standard treatment protocol has been clearly identified.