Antiangiogenic therapies for mesothelioma

Target Therapy in Malignant Pleural Mesothelioma: Hope or Mirage?

Malignant Pleural Mesothelioma (MPM) is a rare neoplasm that is typically diagnosed in a locally advanced stage, making it not eligible for radical surgery and requiring systemic treatment. Chemotherapy with platinum compounds and pemetrexed has been the only approved standard of care for approximately 20 years, without any relevant therapeutic advance until the introduction of immune checkpoint inhibitors. Nevertheless, the prognosis remains poor, with an average survival of only 18 months. Thanks to a better understanding of the molecular mechanisms underlying tumor biology, targeted therapy has become an essential therapeutic option in several solid malignancies. Unfortunately, most of the clinical trials evaluating potentially targeted drugs for MPM have failed. This review aims to present the main findings of the most promising targeted therapies in MPM, and to explore possible reasons leading to treatments failures. The ultimate goal is to determine whether there is still a place for continued preclinical/clinical research in this area.

Increased production of matrix metalloproteinase-7 (MMP-7) by asbestos exposure enhances tissue migration of human regulatory T-like cells

The effects of asbestos on immunocompetent cells have been investigated. In particular, attention was paid to regulatory T cell function, which was observed using the HTLV-1 immortalized human polyclonal T cell line MT-2. Exposure to asbestos (approximately more than 25 μg/mL for 1-3 day) induced apoptosis, and we observed an increase in regulatory T cell function and acceleration of the cell cycle with continuous exposure to low concentrations of asbestos (5-10 μg/mL for more than eight months). Furthermore, cDNA microarray analysis in this study revealed that expression of matrix metalloproteinase-7 (MMP-7) was markedly higher in exposed sublines compared to original MT-2 cells. It was determined that MMP-7 had no effect on Treg function, as determined by examination of sublines and by addition of recombinant MMP-7 and neutralizing antibodies or inhibitors of MMP-7. However, when examining melting of the extracellular matrix (an MMP-7-mediated event) or the extent to which the MT-2 parent strain or long-term exposed subline cells pass through a fibronectin-coated filter, more filter passes were observed for the subline. These results suggest that the effect of asbestos fibers on Treg cells results in excessive migration of the tumor microenvironment through hypersecretion of MMP-7 together with an increase in suppressive function and enhancement of cell cycle progression. Therefore, one possible way to prevent the development of asbestos-induced cancer is to reduce the function (including MMP-7 production) or amount of Treg cells by physiologically active substances or food ingredients. Alternatively, it may be possible to invoke immune checkpoint treatments when carcinogenesis occurs.

Bevacizumab plus cisplatin/pemetrexed then bevacizumab alone for unresectable malignant pleural mesothelioma: A Japanese safety study

Aims

Malignant pleural mesothelioma (MPM) is an aggressive malignancy with poor prognosis and limited treatment options. Cisplatin plus pemetrexed is the only approved first‐line treatment for patients with unresectable MPM. Recently, promising outcomes were observed with first‐line bevacizumab combined with cisplatin/pemetrexed, leading to the recommendation of this regimen as a first‐line treatment option for patients with MPM. Bevacizumab plus cisplatin/pemetrexed has been shown to be safe and effective in non–small cell lung cancer, however, there are no efficacy or safety data in Japanese patients with MPM treated with this regimen. We conducted a multicenter study to evaluate tolerability and safety for Japanese patients with chemotherapy‐naïve, unresectable MPM.

Methods

Eligible patients (n = 7) received bevacizumab plus cisplatin/pemetrexed (up to six cycles), then single‐agent bevacizumab until disease progression or onset of unacceptable adverse events (AEs), according to the 3+3 design analogy.

Results

One patient (14.3%) reported an AE (gastric ulcer) meeting tolerability criteria. All patients experienced gastrointestinal disorders, including nausea (grade 1/2 only, n = 6, 85.7%) and constipation (grade 1/2 only, n = 5, 71.4%). Five patients (71.4%) had grade 3 hypertension. Two patients discontinued treatment due to gastric ulcer (n = 1) and proteinuria (n = 1). At data cut‐off, four patients had stable disease, two had partial response and one had non‐complete response/non‐progressive disease due to the absence of target lesions.

Conclusions

Bevacizumab plus cisplatin/pemetrexed then bevacizumab was well tolerated in Japanese patients with MPM.

The resistance related to targeted therapy in malignant pleural mesothelioma: Why has not the target been hit yet?

Malignant pleural mesothelioma (MPM) is an aggressive tumor of the pleura with a poor prognosis. The most active first-line regimens are platinum compounds and pemetrexed. There is no standard second-line treatment in MPM. Advances in the understanding of tumor molecular biology have led to the development of several targeted treatments, which have been evaluated in clinical trials. Unfortunately none of the explored targeted treatments can currently be recommended as routine treatment in MPM. We reviewed the biological pathways involved in MPM, the clinical trials about targeted therapy, and possible related mechanisms of resistance. We suggest that specific genetic markers are needed as targets of selective therapy. By this way the selection of patients based on the molecular profile may facilitate a therapeutic strategy that allows the use of the most appropriate drug for each patient.

Clinical and biologic prognostic factors in malignant pleural mesothelioma

Malignant pleural mesothelioma is an extremely aggressive neoplasm of the pleura mainly attributable to asbestos exposure. Conventional medical, physical, and surgical treatments and their combinations are basically ineffective and just a few subjects experience some benefit. No definite guidelines can be provided in patient selection and therapeutic strategies. Currently, malignant pleural mesothelioma therapy is guided by clinical stage and patient characteristics, which are quite unreliable, rather than by the histological or molecular features of the tumor. In the present review the impact on prognosis of classic (i.e. etiology, age, gender, histology, staging), as well as relatively new clinical factors such as quality of life, positron emission tomography assessment, and occult residual disease, are firstly evaluated. In the second section of the review several biological variables and genetic markers, which have been recently recognized as the bases of the disease onset and development, are listed and discussed. There are serum and tissue markers. The latter are mainly related to cell cycle regulation, apoptosis, and growth factor pathways. These novel factors may play an important role in defining the prognosis of the disease and, subsequently, may have a place in addressing therapy.

Dendritic cell-based immunotherapy in mesothelioma

Mesothelioma is a rare thoracic malignancy with a dismal prognosis. Current treatment options are scarce and clinical outcomes are rather disappointing. Due to the immunogenic nature of mesothelioma, several studies have investigated immunotherapeutic strategies to improve the prognosis of patients with mesothelioma. In the last decade, progress in knowledge of the modulation of the immune system to attack the tumor has been remarkable, but the optimal strategy for immunotherapy has yet to be unraveled. Because of their potent antigen-presenting capacity, dendritic cells are acknowledged as a promising agent in immunotherapeutic approaches in a number of malignancies. This review gives an update and provides a future perspective in which immunotherapy may improve the outcome of mesothelioma therapy.

Multicenter, double-blind, placebo-controlled, randomized phase II trial of gemcitabine/cisplatin plus bevacizumab or placebo in patients with malignant mesothelioma

PURPOSE

Gemcitabine plus cisplatin is active in malignant mesothelioma (MM), although single-arm phase II trials have reported variable outcomes. Vascular endothelial growth factor (VEGF) inhibitors have activity against MM in preclinical models. We added the anti-VEGF antibody bevacizumab to gemcitabine/cisplatin in a multicenter, double-blind, placebo-controlled randomized phase II trial in patients with previously untreated, unresectable MM.

PATIENTS AND METHODS

Eligible patients had an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1 and no thrombosis, bleeding, or major blood vessel invasion. The primary end point was progression-free survival (PFS). Patients were stratified by ECOG performance status (0 v 1) and histologic subtype (epithelial v other). Patients received gemcitabine 1,250 mg/m(2) on days 1 and 8 every 21 days, cisplatin 75 mg/m(2) every 21 days, and bevacizumab 15 mg/kg or placebo every 21 days for six cycles, and then bevacizumab or placebo every 21 days until progression.

RESULTS

One hundred fifteen patients were enrolled at 11 sites; 108 patients were evaluable. Median PFS time was 6.9 months for the bevacizumab arm and 6.0 months for the placebo arm (P = .88). Median overall survival (OS) times were 15.6 and 14.7 months in the bevacizumab and placebo arms, respectively (P = .91). Partial response rates were similar (24.5% for bevacizumab v 21.8% for placebo; P = .74). A higher pretreatment plasma VEGF concentration (n = 56) was associated with shorter PFS (P = .02) and OS (P = .0066), independent of treatment arm. There were no statistically significant differences in toxicity of grade 3 or greater.

CONCLUSION

The addition of bevacizumab to gemcitabine/cisplatin in this trial did not significantly improve PFS or OS in patients with advanced MM.

Vatalanib in malignant mesothelioma: a phase II trial by the Cancer and Leukemia Group B (CALGB 30107)

INTRODUCTION

The Cancer and Leukemia Group B (CALGB) conducted a multi-center phase II trial to evaluate the efficacy and safety of vatalanib in previously untreated patients with malignant mesothelioma and to evaluate potential biomarkers of disease response (CALGB 30107).

METHODS

Treatment consisted of vatalanib 1250 mg given orally once daily. CT scans were obtained at baseline and every 6 weeks thereafter. Baseline serum levels of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), thrombospondin-1 (TSP-1), and mesothelin were obtained. The primary endpoint was 3-month progression-free survival (PFS).

RESULTS

Forty-seven patients enrolled at 19 centers. The median age was 75 years, and the majority of patients (79%) had an ECOG performance status of 1. Tumors were classified as epithelial (77%), sarcomatoid (10%), or mixed (9%) histology. Toxicity was mild; the most common grade 3/4 adverse events were neutropenia (2%), nausea (15%), elevated alanine aminotransferase (11%), hypertension (2%), and gastrointestinal bleeding (2%). Partial responses were observed in 6% of patients and stable disease in 72% of patients. The 3-month PFS rate was 55% (95% CI: 40%, 68%). The median PFS was 4.1 months. Median overall survival was 10.0 months. There was no correlation between serum levels of VEGF, PDGF, TSP-1, or mesothelin and treatment response, PFS, or survival.

CONCLUSIONS

Vatalanib as a single agent with this dose and schedule does not warrant further study in this disease.

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.

Review on clinical trials of targeted treatments in malignant mesothelioma

PURPOSE

Malignant mesothelioma (MM) is an aggressive tumor of the serosal surfaces with a poor prognosis. Advances in the understanding of tumor biology have led to the development of several targeted treatments, which have been evaluated in clinical trials. This article is a comprehensive review of all clinical trials evaluating the effect of targeted treatments in MM.

METHODS

An extensive literature search was performed in January 2011 using pubmed and medline. No constraints on publication date were applied.

RESULTS

Thirty-two trials exploring 17 different targeted agents in MM were found. Treatment in first- and second-line targeted agents induced response rates ranging from 0-14% and 0-16%, respectively. The tyrosine kinase inhibitor sunitinib induced partial response in 10% and stable disease in 66% of MPM patients as second-line treatment. A preliminary analysis of a phase II/III trial suggests that addition of bevacizumab to pemetrexed and cisplatin first-line treatment significantly improves disease control (CR + PR + SD) in the bevacizumab arm (73.5%) compared with treatment with pemetrexed and cisplatin without bevacizumab (43.2%) (P = 0.010). Another phase II trial did not observe any significant clinical benefit of adding of bevacizumab to gemcitabine and cisplatin.

CONCLUSIONS

Disease stabilization is reported in some patients with several targeted treatments and might be beneficial in subgroups of patients or in combination with classic chemotherapy. None of the hitherto explored targeted treatments can currently be recommended as standard treatment in MM.

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 (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.

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.

The serine protease HtrA1 is a novel prognostic factor for human mesothelioma

AIMS

The objective of our study was to analyze the potential prognostic value of the expression of the serine protease HtrA1 and of EGFR in 70 malignant mesotheliomas.

MATERIALS & METHODS

Immunohistochemistry was used to determine the expression of HtrA1 and EGFR. Univariate and multivariate analyses were used to correlate expression of these molecular factors in combination with available clinicopathologic data to patient survival.

RESULTS

A positive, statistically significant relationship has been recorded between HtrA1 expression level and survival (p < 0.0001). By contrast, a negative relationship has been identified between EGFR expression and survival (p = 0.02). Moreover, extension of the tumor (T) and involvement of lymph nodes (N) advanced status (p = 0.001 and 0.002, respectively), as well as the sarcomatoid histotype (p = 0.005), correlated significantly with poor survival. Finally, by a multivariate Cox regression analysis, the only immunohistochemical parameter that resulted to influence overall survival was HtrA1 (p = 0.0001). Interestingly, the prognostic value of HtrA1 expression was completely independent from EGFR expression (p < 0.0001).

CONCLUSION

This is the first study of the relationship between HtrA1 expression and survival of mesothelioma patients. The data obtained strongly indicate the utilization of HtrA1 expression as a prognostic parameter for mesothelioma and suggest this serine protease as a possible molecular target for the treatment of malignant mesotheliomas.

Management options for malignant pleural mesothelioma: clinical and cost considerations

Malignant pleural mesothelioma (MPM) is a resistant form of lung cancer that is often related to prior asbestos exposure. While surgical resection and radiotherapy techniques have been refined in recent years, neither has been proven to significantly extend patient survival compared with untreated controls. Until the release of pemetrexed in 2004, even combination chemotherapy regimens often resulted in a response rate of <20%. A recent phase III trial documented a 41.3% response rate for cisplatin plus pemetrexed. In the future, new multimodality regimens featuring novel targeted therapies directed against molecular targets, such as the vascular endothelial growth factor, hold the greatest promise for improved outcomes in MPM. The standard radiographic assessment of response to MPM therapy remains a poor surrogate for clinically relevant endpoints such as median survival. Furthermore, it is not currently known whether aggressive multimodality treatment for MPM will improve survival or quality of life above and beyond symptomatic care. Ongoing clinical trials are comparing chemotherapy and surgery with supportive care in an effort to define the role of different therapies in MPM. MPM treatment is a costly public health issue; after efficacy is proven, additional studies are needed to measure the cost effectiveness of MPM treatment regimens.

Preclinical studies of the proteasome inhibitor bortezomib in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a highly lethal neoplasm that is resistant to chemotherapy. Bortezomib is an FDA-approved proteasome inhibitor that is currently under clinical investigation in multiple neoplasms but has not been studied extensively in MPM. In this report, we determine the biological and molecular response of cultured MPM cells to bortezomib alone and in combination with cisplatin or pemetrexed. We used four MPM cell lines (MS589, H28, H2052, JMN), a normal mesothelial cell line (HM3), and a lung cancer cell line (H23) in survival studies utilizing bortezomib, cisplatin, and pemetrexed alone and in combination by administering concurrently or by varying the order of administration. We determined the effect of bortezomib on the cell cycle, apoptosis, and on the expression of cell cycle proteins p21/WAF1 and p27/KIP1 and on apoptosis-related proteins IAP-1, IAP-2, survivin, and XIAP. Bortezomib was highly cytotoxic to MPM cells and induced both G(2)/M and G(1)/S cell cycle arrest. Apoptosis increased in a concentration- and time-dependent manner in 3 of 4 MPM cell lines. Bortezomib stabilized or increased protein levels of p21/WAF1 and IAP-1 and to a lesser degree p27/KIP1, IAP-2, XIAP, and survivin. In combination studies with cisplatin, bortezomib was generally synergistic at high concentrations and antagonistic at low concentrations. Bortezomib increased the cytotoxicity of cisplatin and pemetrexed in a concentration-dependent manner when administered prior to either. Bortezomib may improve outcome in MPM patients alone or in combination with standard chemotherapy but the order of administration is likely to be important. This study justifies further evaluation of bortezomib in MPM.