Paclitaxel for malignant pleural mesothelioma: a phase II study of the EORTC Lung Cancer Cooperative Group

Mesenchymal stromal cells loaded with Paclitaxel (PacliMES) a potential new therapeutic approach on mesothelioma

Malignant pleural mesothelioma is an asbestos-related tumor originating in mesothelial cells of the pleura that poorly responds to chemotherapeutic approaches. Adult mesenchymal stromal cells derived either from bone marrow or from adipose tissue may be considered a good model for cell-based therapy, a treatment which has experienced significant interest in recent years. The present study confirms that Paclitaxel is effective on mesothelioma cell proliferation in 2D and 3D in vitro cultures, and that 80,000 mesenchymal stromal cells loaded with Paclitaxel inhibit tumor growth at a higher extent than Paclitaxel alone. An in vivo approach to treat in situ mesothelioma xenografts using a minimal amount of 10⁶ mesenchymal stromal cells loaded with Paclitaxel showed the same efficacy of a systemic administration of 10 mg/kg of Paclitaxel. These data strongly support drug delivery system by mesenchymal stromal cells as a useful approach against many solid tumors. We look with interest at the favourable opinion recently expressed by the Italian Drug Agency on the procedure for the preparation of mesenchymal stromal cells loaded with Paclitaxel in large-scale bioreactor systems and their storage until clinical use. This new Advanced Medicinal Therapy Product, already approved for a Phase I clinical trial on mesothelioma patients, could pave the way for mesenchymal stromal cells use as drug delivery system on other solid tumors for adjuvant therapy associated with surgery and radiotherapy.

Relations between approved platinum drugs and non-coding RNAs in mesothelioma

Malignant mesothelioma diseases feature an increasing risk due to their severe forms and their association with asbestos exposure. Platinum(II) complexes such as cisplatin and carboplatin are clinically approved for the therapy of mesothelioma often in combination with antimetabolites such as pemetrexed or gemcitabine. It was observed that pathogenic properties of mesothelioma cells and the response of mesothelioma tumors towards platinum-based drugs are strongly influenced by non-coding RNAs, in particular, by small microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). These non-coding RNAs controlled drug sensitivity and the development of tumor resistance towards platinum drugs. An overview of the interactions between platinum drugs and non-coding RNAs is given and the influence of non-coding RNAs on platinum drug efficacy in mesothelioma is discussed. Suitable non-coding RNA-modulating agents with potentially beneficial effects on cisplatin treatment of mesothelioma diseases are mentioned. The understanding of mesothelioma diseases concerning the interactions of non-coding RNAs and platinum drugs will optimize existing therapy schemes and pave the way to new treatment options in future.

Interplay of non-coding RNAs and approved antimetabolites such as gemcitabine and pemetrexed in mesothelioma

Gemcitabine and pemetrexed are clinically approved antimetabolites for the therapy of mesothelioma diseases. These drugs are often applied in combination with platinum complexes and other drugs. The activity of antimetabolites depended on the expression levels of certain non-coding RNAs, in particular, of small microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). The development of tumor resistance towards antimetabolites was regulated by non-coding RNAs. An overview of the interplay between gemcitabine/pemetrexed antimetabolites and non-coding RNAs in mesothelioma is provided. Further to this, various non-coding RNA-modulating agents are discussed which displayed positive effects on gemcitabine or pemetrexed treatment of mesothelioma diseases. A detailed knowledge of the connections of non-coding RNAs with antimetabolites will be constructive for the design of improved therapies in future.

Paclitaxel-releasing mesenchymal stromal cells inhibit in vitro proliferation of human mesothelioma cells

INTRODUCTION

Malignant pleural mesothelioma (MPM) is a rare fatal asbestos-related malignancy originating in the mesothelial cells of the pleura. A platinum-based doublet containing a third-generation antifolate is the front-line standard of care whilst there are no approved second-line treatments for MPM which remains a disease setting to test the efficacy of new therapeutic agents.

METHODS

Bone marrow mesenchymal stromal cells (BM-MSCs) were loaded with pemetrexed (PMX) and paclitaxel (PTX) according to a standardized procedure. Drug release by both PMX- and PTX-primed BM-MSCs (BM-MSCs/PMX and BM-MSCs/PTX) was tested on the in vitro proliferation of a panel of tumor cell lines including NCI-H28 mesothelioma.

RESULTS

The in vitro anticancer activity of pure PTX was significantly higher than that of PMX against all the cell lines tested (14.7 times higher than that of PMX against NCI-H28). Whereas BM-MSCs did not take up and release PMX in amounts effective on mesothelioma, PTX-loaded BM-MSCs dramatically inhibited mesothelioma proliferation.

CONCLUSIONS

PTX-primed mesenchymal stromal cells successfully inhibit the in vitro proliferation of human mesothelioma cells. Further studies and in vivo testing are required to confirm our preliminary in vitro results as a potential new mesothelioma therapy based on cell drug delivery.

Efficacy of Anti-mesothelin Immunotoxin RG7787 plus Nab-Paclitaxel against Mesothelioma Patient-Derived Xenografts and Mesothelin as a Biomarker of Tumor Response

Purpose: The purpose of this study was to evaluate the antitumor efficacy of the reduced immunogenicity anti-mesothelin immunotoxin RG7787 plus nab-paclitaxel against primary mesothelioma cell lines and tumor xenografts and the utility of mesothelin as a biomarker of tumor response.Experimental Design: Early-passage human malignant mesothelioma cell lines NCI-Meso16, NCI-Meso19, NCI-Meso21, and NCI-Meso29 were evaluated for sensitivity to RG7787 or nab-paclitaxel alone or in combination. In addition, the antitumor activity of RG7787 plus nab-paclitaxel was evaluated using NCI-Meso16, NCI-Meso21, and NCI-Meso29 tumor xenografts in immunodeficient mice. Serum mesothelin was measured at different time points to determine whether its levels correlated with tumor response.Results: All four primary mesothelioma cell lines highly expressed mesothelin with 41 × 10³ to 346 × 10³ mesothelin sites per cell and were sensitive to RG7787, with IC₅₀ ranging from 0.3 to 10 ng/mL. Except for NCI-Meso19, these cells were also sensitive to nab-paclitaxel, with IC₅₀ of 10 to 25 ng/mL. In vitro, RG7787 plus nab-paclitaxel led to decreased cell viability compared with either agent alone. In NCI-Meso16 tumor xenografts, treatment with RG7787 plus nab-paclitaxel led to sustained complete tumor regressions. Similar antitumor efficacy was observed against NCI-Meso21 and NCI-Meso29 tumor xenografts. In all three tumor xenograft models, changes in human serum mesothelin correlated with response to therapy and were undetectable in mice with complete tumor regression with RG7787 and nab-paclitaxel.Conclusions: RG7787 plus nab-paclitaxel is very active against primary human mesothelioma cells in vitro as well as in vivo, with serum mesothelin levels correlating with tumor response. These results indicate that this combination could be useful for treating patients with mesothelioma. Clin Cancer Res; 23(6); 1564-74. ©2016 AACR.

Paclitaxel-loaded expansile nanoparticles enhance chemotherapeutic drug delivery in mesothelioma 3-dimensional multicellular spheroids

OBJECTIVES

Intraperitoneal administration of paclitaxel-loaded expansile nanoparticles (Pax-eNPs) significantly improves survival in an in vivo model of malignant mesothelioma compared with conventional drug delivery with the clinically utilized Cremophor EL/ethanol (C/E) excipient. However, in vitro monolayer cell culture experiments do not replicate this superior efficacy, suggesting Pax-eNPs utilize a unique mechanism of drug delivery. Using a mesothelioma spheroid model, we characterized the mechanisms of enhanced tumor cytotoxicity leveraged by Pax-eNPs.

METHODS

Human malignant mesothelioma (MSTO-211H) spheroids were co-incubated for 24 hours with Oregon Green-conjugated paclitaxel dissolved in C/E or loaded into eNPs. Oregon Green-paclitaxel uptake was measured as Oregon Green intensity via confocal microscopy and kinetics of tumor cytotoxicity were assessed via propidium iodide staining. Pharmacologic endocytotic inhibitors were used to elucidate mechanisms of eNP uptake into spheroids.

RESULTS

Increased drug penetration and a 38-fold higher intraspheroidal drug concentration were observed 24 hours after MSTO-211H spheroids were treated with Oregon Green-conjugated paclitaxel loaded into eNPs compared with Oregon Green-conjugated paclitaxel dissolved in C/E (P < .01). Macropinocytosis was the dominant endocytotic pathway of eNP uptake. Spheroids were more susceptible to paclitaxel when delivered via eNP, exhibiting more than twice the propidium iodine intensity compared with an equivalent paclitaxel-C/E dose.

CONCLUSIONS

Compared with monolayer cell culture, the in vitro 3-D tumor spheroid model better reflects the superior in vivo efficacy of Pax-eNPs. Persistent tumor penetration and prolonged intratumoral release are unique mechanisms of Pax-eNP cytotoxicity. 3-D spheroid models are valuable tools for investigating cytotoxic mechanisms and nanoparticle-tumor interactions, particularly given the costs and limitations of in vivo animal studies.

A 26-year-old male with mesothelioma due to asbestos exposure

Mesothelioma is a malignancy with poor prognosis, with an average 5-year survival rate being less than 9%. This type of cancer is almost exclusively caused by exposure to asbestos. A long exposure can cause mesothelioma and so can short ones, as each exposure is cumulative. We report a case of a 26-year-old male who was exposed to asbestos during his primary school years from the age of 6 to 12. Although the tumor mainly affects older men who in their youth were occupationally exposed to asbestos, malignant mesothelioma can also occur in young adults. A medical history was carefully taken and asbestos exposure was immediately mentioned by the patient. We conducted biopsy on the right supraclavicular lymph node. The patient was not a candidate for surgery, and chemotherapy treatment was initiated. While patient's chemotherapy is still ongoing, no other similar cases of students or teachers have been traced up to date from his school. The school building was demolished in January 2009.

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.

Hyperthermia combined with intra-thoracic chemotherapy and radiotherapy for malignant pleural mesothelioma

BACKGROUND

Prognosis for patients with malignant pleural mesothelioma (MPM) remains poor and such patients require intensive treatment. Few studies have examined hyperthermia for MPM. The present study investigated the feasibility of hyperthermia combined with weekly chemo-radiotherapy for patients with MPM and estimated the efficacy of this regimen.

METHODS

A total of 11 patients (median patient age was 67 and all had pleural effusion) with MPM were enrolled in this study. The treatment regimen comprised of weekly thermo-radiotherapy with intra-thoracic chemotherapy 2-5 times at initiation of treatment. Hyperthermia was performed once per week for approximately 60 min. Hemithorax external radiotherapy was administered once weekly on the same day as hyperthermia and just before thermochemotherapy. Median total radiation dose was 6 Gy (range, 2-10 Gy). Chemotherapy was administered into the thoracic cavity through a tube. Chemotherapeutic agents administered were CDDP for seven patients, carboplatinum (CBDCA) for three patients and both CDDP and CBDCA for one patient. Dose of CDDP was 50 mg/body and dose of CBDCA was 200-300 mg m-2. Response rate and median survival time (MST) and palliative effect were investigated.

RESULTS

Complete response was not achieved in any of the 11 patients. Partial response was achieved in three of 11 patients (27.3%), SD in six patients (54.5%) and PD in two patients (18.2%). There was no correlational relationship between thermal parameters and response. MST was 27.1 months. Pleural fluid decreased in all patients after therapy, while all patients displayed improved performance status and could be discharged from hospital. Patients with partial response had a relatively longer survival time than SD or PD. All patients underwent the complete course of treatment and only one of 11 patients developed grade 4 thrombocytopenia.

CONCLUSION

It was therefore concluded that hyperthermia combined with intra-thoracic chemotherapy using cisplatinum or carboplatinum may be tolerable. This approach appears effective and more acceptable for patients with MPM with pleural effusion than other multi-modality therapy.

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.

A prognostic index for progression-free survival in malignant mesothelioma with application to the design of phase II trials: a combined analysis of 10 EORTC trials

PURPOSE

For cytostatic agents or when the response assessment is difficult, adaptations to phase II designs may allow a better assessment of therapeutic activity: first by using the progression-free survival rate (PFSR) as primary end-point instead of the response rate, and second by considering progression-free survival (PFS) risk groups based on a prognostic index (PI). In mesothelioma, current treatments yield disappointingly poor results and there is a need to investigate new regimens. The purpose of this report is to provide a PI for PFS in mesothelioma and reference values for the PFSR.

MATERIALS AND METHODS

Data on 523 patients included in 10 European Organisation for Research and Treatment of Cancer (EORTC) mesothelioma studies were analysed to identify prognostic factors using a multivariate Cox regression model. Subsequently, a PI and a nomogram for PFS were developed. The PFSRs at 3, 4, 5 and 6 months were estimated.

RESULTS

A performance status>0, stage IV disease and mixed or sarcomatous histological type were indicators of a poor prognosis for PFS. From the PI, based on these three variables, four risk groups were defined. The median progression-free survival ranged from 5.3 to 2.1 months in these risk categories. The PFSRs at 3 months were 70.6%, 62.4%, 54.2% and 42.1% in the four categories, respectively.

CONCLUSION

The PI allows dividing patients into homogeneous risk categories in which PFSRs can be calculated and used to design future phase II mesothelioma trials. Defining homogeneous categories of patients avoids dilution of results between groups and improves the assessment of therapeutic activity.

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.

Anti-mesothelin immunotoxin SS1P in combination with gemcitabine results in increased activity against mesothelin-expressing tumor xenografts

PURPOSE

To determine the antitumor activity of the anti-mesothelin immunotoxin SS1P in combination with gemcitabine against mesothelin-expressing tumor xenografts.

EXPERIMENTAL DESIGN

The in vitro activity of SS1P in combination with gemcitabine against the mesothelin-expressing cell line A431/K5 was evaluated using cytotoxicity and apoptosis assays. The antitumor activity of this combination was evaluated in nude mice bearing A431/K5 tumor xenografts. Tumor-bearing mice were treated with different doses and schedules of gemcitabine alone, SS1P alone (0.2 mg/kg i.v. every other day x three doses), or with both agents together, and tumor volumes were measured over time.

RESULTS

In vitro studies failed to show the synergy of SS1P plus gemcitabine against the mesothelin-expressing A431/K5 cells. In contrast, in the in vivo setting, there was a marked synergy when SS1P was combined with gemcitabine for the treatment of mesothelin-expressing tumor xenografts. This synergy was present using different doses and schedules of gemcitabine administration. In mice treated with fractionated doses of gemcitabine in combination with SS1P, complete tumor regression was observed in all mice and was long-lasting in 60% of the animals. Also, this antitumor activity was specific to SS1P because HA22, an immunotoxin targeting CD22 not expressed on A431/K5 cells, did not increase the efficacy of gemcitabine.

CONCLUSIONS

SS1P in combination with gemcitabine results in marked antitumor activity against mesothelin-expressing tumors. This combination could be potentially useful for the treatment of human cancers that express mesothelin and are responsive to gemcitabine therapy.

Multidisciplinary treatment of malignant pleural mesothelioma

The incidence of malignant pleural mesothelioma (MPM) is increasing worldwide, and is predicted to peak in the next 10-20 years. Difficulties in MPM diagnosis and staging, especially of early disease, have thwarted the development of a universally accepted therapeutic approach. Single modality therapies (surgery, radiotherapy, chemotherapy) have generally failed to significantly prolong patient survival. As a result, multimodality treatment regimens have been developed. Radical surgery with extrapleural pneumonectomy and adjuvant treatments has become the preferred option in early disease, but the benefits of such an aggressive approach have been questioned because of significant treatment-related morbidity and mortality. In the past few years, there have been several major advances in the management of patients with MPM, including more accurate staging and patient selection, improvements in surgical techniques and postoperative care, novel chemotherapy regimens with definite activity such as antifolate (pemetrexed or raltitrexed)-platinum combinations, and new radiotherapy techniques such as intensity-modulated radiation therapy. Induction chemotherapy followed by surgery and adjuvant radiotherapy has shown promising results. A number of molecular alterations occurring in MPM have been reported, providing broader insights into its biology and leading to the identification of new targets for therapy. However, currently available treatments still appear to have modest results. Further studies are needed to provide evidence-based recommendations for the treatment of early and advanced stages of this disease.

Emerging drugs for mesothelioma

Malignant mesothelioma is an aggressive, but relatively rare, malignancy, affecting the pleura and peritoneum. The prognosis for malignant pleural mesothelioma (MPM) is poor, with median survival in the range of 8-14 months, depending on stage and presentation of disease. Long-term results of available treatments are disappointing not only in terms of prognosis, but also of local control of the disease. Therefore, relief of symptoms and improvement of quality of life parameters are the short-term goals of therapy. In advanced disease not amenable to any local approach, such as surgery, combination chemotherapy represents the current standard of care. At present, the regimen of cisplatin/pemetrexed is the medical treatment of choice. This review summarizes standard chemotherapy options and focuses on the molecular basis of the newest biologically targeted therapies to be implemented in the near future, in the management of MPM.

Divided dose of cisplatin combined with gemcitabine in malignant mesothelioma

Malignant mesothelioma is a rare but notoriously chemoresistant tumor. An impressive activity of gemcitabine and cisplatin combination in malignant mesothelioma has been shown. However, the hematological toxicity and nephrotoxicity related to this regimen affect the patient's life negatively. The aim of this study is to investigate the efficacy and toxicity of divided dose of cisplatin combined with gemcitabine in chemo-naïve patients with malignant mesothelioma. Twenty-six eligible patients with malignant mesothelioma were enrolled onto the study. Cisplatin 35 mg/m(2) and gemcitabine 800 mg/m(2) were administered on days 1 and 8 as intravenous infusion in a 3-week cycle, up to maximum 6 cycles. Response and toxicity evaluations were performed in 26 patients. Male-female ratio was 11/15 with a mean age of 50.5 years (37-70). Locations of tumor were pleura in 16 patients, and peritoneum in 10 patients. All patients had epitheloid subtype of malignant mesothelioma. The partial response and stable disease were observed in 6 patients (23.1%) and in 13 patients (50%), respectively, with an overall tumor control rate of 73.1%. Seven patients (26.9%) had progressive disease. Median time to disease progression and survival were 4 and 19.5 months, respectively. Grade 3 nausea and vomiting were observed in one patient (3.8%), grade 4 neutropenia developed in one patient (3.8%) and grades 3-4 thrombocytopenia and nephrotoxicity did not develop. There was no treatment related death. Divided dose of cisplatin combined with gemcitabine, at the current dosage and schedule, appears to be an active regimen in chemotherapy-naïve patients with malignant mesothelioma, and well-tolerated.

Progression-Free Survival Rate As Primary End Point for Phase II Cancer Clinical Trials: Application to Mesothelioma—The EORTC Lung Cancer Group

Purpose

Phase II cancer clinical trials play a key role in the development of new drugs. These trials should be designed to accurately determine if the drug should be abandoned or if it is sufficiently promising for further investigation in phase III trials. With new cytostatic agents or when the response assessment is difficult, using the progression-free survival rate (PFSR) at a fixed time point, such as 3, 4, 5, or 6 months, instead of the response rate (RR) as the primary end point is an alternative approach. To design future phase II trials, reference values for PFSRs that correspond to drugs with insufficient (P0) and sufficient (P1) clinical activity (CA) are necessary. This article provides these values in mesothelioma.

Materials and Methods

The European Organisation for Research and Treatment of Cancer database registered ten closed mesothelioma trials (nine phase II trials and one phase III trial) with 523 total patients. Trials were grouped into three categories according to the published RR: significant (n = 259), moderate (n = 142), and insufficient (n = 122) CA.

Results

The PFSRs at 3, 4, 5, and 6 months, respectively, were as follows: 72%, 67%, 51%, and 43% in the group with significant CA; 59%, 51%, 42%, and 35% with moderate CA; and 52%, 40%, 34%, and 28% with insufficient CA.

Conclusion

These values may be used to define relevant P0 and P1 values in future phase II mesothelioma trials that use PFSR as the primary end point.

Pemetrexed in thoracic cancer

Both lung cancer and mesothelioma are malignancies with increasing incidence, and both are primarily due to inhalation of an external carcinogen. The occurence of both diseases is expected to rise worldwide, although a stabilisation and/or decrease may be anticipated in some developed countries. There are other common similarities to both cancers, including the median age of their patients, the advanced stage at presentation, the outcome and the treatments given. This review focuses on the available evidence of a novel antifolate agent, pemetrexed, in the treatment of both of these thoracic malignancies. Current status, persisting controversies and future developments are discussed.

Global Gene Expression Profiling of Pleural Mesotheliomas: Overexpression of Aurora Kinases and P16/CDKN2A Deletion as Prognostic Factors and Critical Evaluation of Microarray-Based Prognostic Prediction

Most gene expression profiling studies of mesothelioma have been based on relatively small sample numbers, limiting their statistical power. We did Affymetrix U133A microarray analysis on 99 pleural mesotheliomas, in which multivariate analysis showed advanced-stage, sarcomatous histology and P16/CDKN2A homozygous deletion to be significant independent adverse prognostic factors. Comparison of the expression profiles of epithelioid versus sarcomatous mesotheliomas identified many genes significantly overexpressed among the former, including previously unrecognized ones, such as uroplakins and kallikrein 11, both confirmed by immunohistochemistry. Examination of the gene expression correlates of survival showed that more aggressive mesotheliomas expressed higher levels of Aurora kinases A and B and functionally related genes involved in mitosis and cell cycle control. Independent confirmation of the negative effect of Aurora kinase B was obtained by immunohistochemistry in a separate patient cohort. A role for Aurora kinases in the aggressive behavior of mesotheliomas is of potential clinical interest because of the recent development of small-molecule inhibitors. We then used our data to develop microarray-based predictors of 1 year survival; these achieved a maximal accuracy of 68% in cross-validation. However, this was inferior to prognostic prediction based on standard clinicopathologic variables and P16/CDNK2A status (accuracy, 73%), and adding the microarray model to the latter did not improve overall accuracy. Finally, we evaluated three recently published microarray-based outcome prediction models, but their accuracies ranged from 63% to 67%, consistently lower than reported. Gene expression profiling of mesotheliomas is an important discovery tool, but its power in clinical prognostication has been overestimated.

An overview of chemotherapy for mesothelioma

Mesothelioma is an extraordinarily challenging disease to treat. While numerous clinical trials testing various chemotherapeutic agents have been conducted over the last several decades, only recently have larger studies proven the efficacy of newer chemotherapy regimens. This article reviews the data regarding specific classes of chemotherapeutic agents. The role of treatment in various disease settings and the difficulty in assessing the benefit of that therapy is discussed. Finally, an update is provided on novel therapeutics being testing in mesothelioma.

Randomized phase III study of cisplatin with or without raltitrexed in patients with malignant pleural mesothelioma: an intergroup study of the European Organisation for Research and Treatment of Cancer Lung Cancer Group and the National Cancer Institute of Canada

PURPOSE

We conducted a phase III trial to determine whether first-line treatment with raltitrexed, a thymidine synthase inhibitor, and cisplatin results in superior outcome compared with cisplatin alone in patients with malignant pleural mesothelioma (MPM).

PATIENTS AND METHODS

Eligible patients with histologically proven advanced MPM, not pretreated with chemotherapy, WHO performance status (PS) 0 to 2, and adequate hematological, renal, and hepatic function were randomly assigned to receive cisplatin 80 mg/m2 IV on day 1, alone (arm A) or combined with raltitrexed 3 mg/m2 (arm B). In patients with measurable disease, response was monitored using the Response Evaluation Criteria in Solid Tumors criteria. Health related quality of life (HRQOL) was measured using the European Organisation for Research and Treatment of Cancer QLQ-C30 and Lung Module (QLQ-LC13).

RESULTS

Two hundred fifty patients were randomized: 80% male; median age, 58 years; and WHO PS, 0, 1, 2 in 25, 62, and 13% of cases, respectively. There were no toxic deaths. The main grade 3 or 4 toxicities observed were neutropenia and emesis, reported twice as often in the combination arm. Among 213 patients with measurable disease, response rate was 13.6% (arm A) versus 23.6% (arm B; P = .056). No difference in HRQOL was observed on any of the scales. Median overall and 1-year survival in arms A and B were 8.8 (95% CI, 7.8 to 10.8) v 11.4 months (95% CI, 10.1 to 15), respectively, and 40% v 46%, respectively (P = .048).

CONCLUSION

A combination of raltitrexed and cisplatin improves overall survival compared with cisplatin alone. This study confirms that a combination of cisplatin and an antifolate is superior to cisplatin alone in patients with MPM, without harmful effect on HRQOL.

Docetaxel for malignant mesothelioma: phase II study of the Eastern Cooperative Oncology Group

This Eastern Cooperative Oncology Group phase II trial was conducted to study the effectiveness of docetaxel in patients with malignant mesothelioma. Patients were treated with docetaxel 100 mg/m2 intravenously administered as a 1-hour infusion repeated every 3 weeks. The study accrued a total of 20 patients, 1 of whom was considered ineligible. Of the 19 eligible patients, 1 patient (5%) achieved a partial response, 3 patients (16%) had stable disease, 11 patients (58%) had progressive disease, and 4 patients (21%) were unevaluable. The study was terminated after the first accrual stage because of an insufficient number of complete or partial responses. To date, only 1 patient (with stable disease) has not relapsed. The estimated median survival time is 4 months and the estimated median time to treatment failure is 2.2 months. There were 3 early deaths associated with the treatment regimen: severe gastrointestinal toxicity, hemorrhage, and an acute pulmonary event. Docetaxel as a single agent does not demonstrate evidence of activity in malignant mesothelioma.

Chemotherapy for malignant pleural mesothelioma: past results and recent developments

This review summarises results of previously conducted clinical trials and subsequently presents data arising from all phase II-III studies on chemotherapy for malignant pleural mesothelioma (MPM) published since the last relevant overview. While response rates exceeding 30% have barely been achieved with established cytotoxic drugs in MPM therapy, novel chemotherapeutic agents and their combinations appear somewhat more promising. This applies especially to the antimetabolites, and in particular to pemetrexed which produced response rates of up to 45% in combination with platinum compounds. Raltitrexed combined with oxaliplatin has also been shown to be effective, and gemcitabine--applied as a single agent or in combination with cisplatin--as well as vinorelbine appear to improve quality of life in patients presenting with MPM. Data can now be more precisely analysed by increasingly implemented randomised studies, applying a standardised staging system, and distinguishing prognostic groups. While chemotherapy for MPM remains a challenging task, important steps have clearly been made in the past years to combat this aggressive disease. Publication of results from a phase III trial of pemetrexed with cisplatin in a peer reviewed journal may soon establish a standard of care.

Malignant Pleural Mesothelioma

The diagnosis and management of malignant pleural mesothelioma are major challenges that often frustrate both patient and clinician alike. Occupational asbestos exposure to crocidolite or amosite forms of the fiber is the most important known risk factor in North America and Western Europe. Other mineral fibers such as erionite, a naturally occurring fibrous zeolite crystal, are associated with mesothelioma in volcanic tuffs of the Cappadocia region of central Anatolia in Turkey. In addition, other possible factors such as the presence of simian virus 40 and genetic susceptibility have been associated recently with the development of mesothelioma in animal models. These latter findings are increasing our understanding of this disease. In addition, the discovery of elevated levels of various markers such as folic acid receptor alpha, cyclooxygenase 2, and multidrug resistance proteins 1 and 2 in mesothelioma tissue have opened up new areas of potential diagnostic and therapeutic importance. However, traditional treatment modalities--surgery, radiotherapy, and chemotherapy--have evolved slowly, and few gains in therapeutic efficacy have occurred. Recently, however, continuing research efforts have led to novel treatment strategies that are changing the way clinicians view a disease that has traditionally been managed with almost universal therapeutic nihilism. This review explores our current knowledge of this disease and presents current and novel therapeutic strategies.

Experimental therapy of malignant mesothelioma: new perspectives from anti-angiogenic treatments

We reviewed the published literature of clinical studies in malignant mesothelioma (MM), including phase II as well as older single-agent and combination chemotherapy trials with more than 15 patients. While response rates exceeding 30% have been achieved with established cytotoxic drugs in MM therapy, novel chemotherapeutic agents and their combinations appear more promising. This applies especially to the anti-metabolites (i.e. pemetrexed) that produced response rates of up to 45% in combination with platinum compounds. Moreover, agents targeting novel proliferative and survival pathways in MM are developed to improve treatment outcomes. Here, we focused on the role of several angiogenic growth factors in MM biology and the data of MM-oriented studies on angiostatic agents tested in a phase I-II trial. It seems likely that no single treatment modality will be effective by itself. Studies that use combinations of the newer agents, including angiostatic drugs, with chemotherapy, should be conducted.

Novel Combinations Using Pemetrexed in Malignant Mesothelioma

Malignant mesothelioma is an uncommon malignancy that is locally invasive and rapidly fatal. The majority of patients with mesothelioma are not candidates for curative surgical resection. Chemotherapy has yielded only modest results in these patients. Pemetrexed is a multitargeted antifolate that is being evaluated in many tumor types. Recent single-agent data and data in combination with cisplatin have suggested that pemetrexed has therapeutic benefits in patients with malignant mesothelioma. This article summarizes the data regarding pemetrexed in the treatment of malignant mesothelioma and the potential novel combinations involving the drug that may be used in the future for the treatment of the disease.

Chemotherapy for Malignant Pleural Mesothelioma

Malignant pleural mesothelioma is an aggressive malignancy with no known single curative modality. Most patients are candidates for chemotherapy at some point in their treatment, but no standard regimen has been established. Several phase II single-agent and combination chemotherapy studies have been performed over the past 2 decades. Although the true impact of chemotherapy in mesothelioma remains to be determined, agents with consistent antitumor activity include doxorubicin, platinum agents, and antimetabolites. Combination chemotherapy is associated with higher response rates, but not necessarily longer median survivals. Large randomized trials, which are currently ongoing or have been performed in the past few years, will yield important answers in regard to the role of chemotherapy and the efficacy of various single and combination chemotherapy agents. Furthermore, the biologic and genetic studies of mesothelioma have identified several receptor tyrosine kinases that are aberrantly expressed in these tumors. Orally available small molecule inhibitors of several receptor tyrosine kinases have been developed and are now being evaluated in clinical trials.

Chemotherapy for malignant pleural mesothelioma

This paper covers the outcome of previously conducted clinical trials on chemotherapy for malignant pleural mesothelioma and presents data from recent phase II and phase III trials. In contrast to conventional cytotoxic drugs, which have barely produced response rates exceeding 30%, recently introduced chemotherapeutic agents and their combinations promise to be more effective. Especially pemetrexed has yielded response rates of up to 45% in combination with platinum compounds. Furthermore, raltitrexed-oxaliplatin has shown promising activity and gemcitabine was found to improve quality of life in patients with malignant pleural mesothelioma when applied as a single agent or in combination with cisplatin. Based on robust phase III study results, pemetrexed-cisplatin may soon be considered with chemotherapy for this aggressive disease.

The activity of raltitrexed (Tomudex) in malignant pleural mesothelioma: an EORTC phase II study (08992)

We investigated the activity and toxicity of raltitrexed (Tomudex) as a single agent treatment in patients with Malignant Pleural Mesothelioma (MPM) in a multicentre phase II European Organization for Research and Treatment of Cancer (EORTC) study. This study enrolled chemonaíve patients with histologically-confirmed measurable MPM. Raltitrexed was administered at the dose of 3 mg/m(2) intravenous (i.v.) bolus on an outpatient basis every 3 weeks. A maximum of eight cycles was planned in cases with an absence of progression or unacceptable toxicity. 24 patients received a total of 104 courses. 5 patients (20.8%, 95% confidence interval (CI) 7.1-42.2%) had a partial response (PR), which was confirmed by an independent radiology committee. Toxicity was mild, with diarrhoea, nausea, vomiting, fatigue and neutropenia as the major side-effects, but not exceeding grade 3 toxicity. We conclude that raltitrexed has activity as a single agent in the treatment of MPM, and that further studies with this drug in MPM are warranted.

Chemotherapy for malignant pleural mesothelioma: past results and recent developments

This review summarises the results of previously conducted clinical trials, and subsequently presents data arising from all phase II-III studies on chemotherapy of malignant pleural mesothelioma (MPM) published since the last relevant overview. While response rates exceeding 30% have barely been achieved with established cytotoxic drugs in MPM therapy, novel chemotherapeutic agents and their combinations appear more promising. This applies especially to the antimetabolites, and in particular to pemetrexed that produced response rates of up to 45% in combination with platinum compounds. Raltitrexed combined with oxaliplatin has also been shown to be effective, and gemcitabine-applied as a single agent or in combination with cisplatin-as well as vinorelbine appear to improve the quality of life in patients presenting with MPM. Data can now be more precisely analysed by increasingly implemented randomised studies, applying a standardised staging system, and distinguishing prognostic groups. While chemotherapy for MPM remains a challenging task, important steps have clearly been made in the past years to combat this aggressive disease. The publication of pemetrexed with cisplatin phase III results in a peer-reviewed journal may soon establish a standard of care.

Activity of chemotherapy and immunotherapy on malignant mesothelioma: a systematic review of the literature with meta-analysis

The role of chemotherapy for unresectable malignant mesothelioma is unclear. The aims of the present study were to evaluate the methodological quality of published papers relative to chemotherapy or immunotherapy in malignant mesothelioma and to aggregate, for trials having a similar methodology, the response rates in order to identify the most active chemotherapeutic drugs and regimens. The literature relative to this topic, published between 1965 and June 2001 was reviewed. A methodological qualitative evaluation was performed according to the European Lung Cancer Working Party scale, specifically designed for phase II trials. A study was considered as potentially positive if the upper limit of the 95% confidence interval (CI) of the response rate was greater than 20% and positive if the lower limit of the 95% CI was > 20%. Eighty-three studies (88 treatment arms) were eligible for the systematic review. Fifty-three arms were considered as positive or potentially positive. No statistically significant difference in the methodological quality was observed between negative and positive studies. Studies were aggregated in four groups according to the presence of cisplatin and/or doxorubicin in the treatment regimen. The combination of cisplatin and doxorubicin had the highest response rate (28.5%; P < 0.001). Cisplatin was the most active single-agent regimen. Our systematic qualitative and quantitative overview of the literature suggests that the most active chemotherapeutic regimen, in term of objective response rate, is the combination of cisplatin and doxorubicin and the best single-agent is cisplatin. The combination of these two drugs can be recommended as control arm for future randomised phase III trials.

Malignant mesothelioma: options for management

In the past, there has been a tendency to think of diffuse malignant pleural mesothelioma as one disease in therapeutic terms, regardless of histological type and tumor stage. This does not happen with other tumors, yet it is equally illogical and inappropriate in mesothelioma. As with other tumors, early diagnosis-while the disease is still in stage I, or even at an in situ stage-must be the goal so that therapy can be maximized, particularly if immunotherapy or gene therapy is to be used. Patients with pure epithelial mesothelioma have a better prognosis and respond better to trimodality therapy. Stage I patients who meet fitness criteria should be offered the option of radical surgery in combination with chemotherapy and radiotherapy. Further research is required to determine the optimum neoadjuvant and adjuvant modalities, particularly the timing of individual drugs, use of hyperthermia, and route of administration. The place of immunotherapy and gene therapy as adjunctive treatments also remains to be defined. For example, it may be possible to reduce tumor bulk and perhaps downstage the disease with immunotherapy before radical surgery, if treatment is started early enough. Gene therapy may have a role either preoperatively or in destroying the microscopic disease that remains after radical surgery. These and other combinations of treatment need to be tested in well-designed clinical trials, probably on a multicenter basis (to enroll a sufficient number of patients). Finding the means to improve treatment for sarcomatous and mixed histology mesothelioma remains a challenge. At present, radical surgery does not seem worthwhile for these patients when combined with currently employed chemotherapy and radiotherapy; however, chemotherapy combinations used for treating other sarcomas need to be evaluated as adjunctive therapy before radical surgery is abandoned altogether as a mode of treatment. A collaborative approach involving thoracic surgeons, basic scientists and oncologists, and physicians with experience in treating mesothelioma is essential. Despite its increasing frequency, mesothelioma is still a relatively rare tumor, so treatment should be concentrated in relatively few supraregional centers to maximize expertise and allow innovative treatment combinations to be implemented with the greatest chance of success. Evaluation of new therapeutic approaches will be achieved more rapidly if these supraregional centers collaborate in multicenter trials. The nihilistic approach of simply waiting until the mesothelioma epidemic eventually begins to decline spontaneously in 20 or 30 years is untenable in view of the hundreds of thousands of deaths that will result if no effective treatment is found.

Antisense therapy for malignant mesothelioma with oligonucleotides targeting the bcl-xl gene product

OBJECTIVE

Malignant pleural mesothelioma is resistant to conventional therapies and to apoptosis. The bcl-2 family genes are major determinants of apoptotic homeostasis. Malignant pleural mesothelioma lines and tumors rarely express the antiapoptotic Bcl-2 protein but routinely express the antiapoptotic protein Bcl-xl and the proapoptotic proteins Bax and Bak. We have previously shown pharmacologic inhibition of bcl-xl expression in malignant pleural mesothelioma can lead to apoptosis, so we sought to determine whether antisense oligonucleotides directed at bcl-xl messenger RNA would engender apoptosis, possibly through a "forced imbalance" of bcl-2 family proteins.

METHODS

Malignant pleural mesothelioma lines REN (epithelial) and I-45 (sarcomatous) were exposed to modified bcl-xl antissense oligonecleotides directed near the messenger RNA initiation sequence with and without a liposomal delivery system. Untreated cells and bcl-xl sense oligonucleotides were controls. Cell viability was measured by colorimetric assay, and apoptosis was evaluated with Hoechst staining and sub-G(1) fluorescence-activated cell sorter analysis.

RESULTS

Bcl-xl protein expression after antisense oligonucleotides was downwardly regulated in both cell lines relative to sense oligonucleotides (>65%). Significant cellular killing in both the I-45 and REN cell lines was achieved with antisense oligonucleotides (compared with sense oligonucleotides) without (P =.003 and.006, respectively) and with (P =.006 and.0005, respectively) liposomal delivery. Hoechst staining and sub-G(1) fluorescence-activated cell sorter analysis demonstrated apoptosis to be the mechanism of cellular death. Use of a liposomal delivery system increased therapeutic effect and allowed lower doses of antisense oligonucleotides.

CONCLUSION

Antisense oligonucleotides directed at the bcl-xl gene product engender apoptosis in mesothelioma cell lines. The therapeutic potential of inhibiting expression of this protein in mesothelioma should be evaluated.

A phase II EORTC study of temozolomide in patients with malignant pleural mesothelioma

The aim of this study was to investigate the anti-tumour activity of temozolomide in patients with malignant pleural mesothelioma. 27 chemotherapy-naïve patients with histologically-proven malignant mesothelioma were treated with temozolomide 200 mg/m2/day, given orally on days 1-5 of each 28-day cycle. Therapy continued up to 10 cycles unless disease progression or excessive toxicity mandated discontinuation. Toxicity, symptom improvement and pain intensity were regularly assessed. With a median relative dose intensity of 97%, toxicity was moderate with grade 3 or more nausea, vomiting, thrombocytopenia, leucocytopenia, neutropenia, febrile leucocytopenia, arthralgia, infection and fever with infection occurring in 13, 13, 10, 3, 7 and 3% of patients for the remaining events, respectively. Overall, 1 objective response was observed (response rate 4%, 95% Confidence Interval (CI): 0.1-19). Median survival was 8.2 months. Symptom assessment showed no improvement and an increase of pain was observed during the study. Thus, oral temozolomide is an inactive agent in malignant mesothelioma.

Malignant pleural mesothelioma: a phase II trial with docetaxel

Current cytotoxic therapy has been of limited benefit to patients with malignant pleural mesothelioma. Single agent chemotherapy has been extensively evaluated in small series of phase II clinical trials, with disappointing responses. Docetaxel, an effective taxane in the treatment of advanced breast cancer and non-small-cell lung cancer, was administered intravenously at a dose of 100 mg/m2 every 3 weeks to 30 chemotherapy naive patients with malignant pleural mesothelioma in a prospective multi-institutional phase II clinical trial. An objective response rate (partial responses) of 10% was documented. Additionally, 21% of the patients had minor responses (intention-to-treat analysis). Three patients died within 2 weeks post-first cycle of therapy, although only one patient's death was directly attributed to the investigational drug, whilst in the majority of the patients, manageable and treatable toxicities were encountered. In this phase II clinical trial, docetaxel proved to be mildly effective in the treatment of patients with malignant pleural mesothelioma.

Overview of past, present and future of the EORTC Lung Cancer Group. European Organisation for Research and Treatment of Cancer

The EORTC Lung Cancer Group (LCG) is a multidisciplinary international group of experts performing clinical research in lung cancer since 1962. Originally, the group consisted mainly out of French and Belgian investigators and expanded gradually into a wide range of investigators from all European Union countries, as well as some investigators from Switzerland, Poland, Czech Republic, Egypt, Slovenia, South Africa, Peru, Brazil and Cyprus. Despite the wide collaboration, it remains a difficult task to perform high quality large clinical research trials to answer important scientific questions in the treatment of lung cancer. For this reason, the EORTC Lung Cancer Group has invested a lot of efforts in promoting worldwide, randomised phase III studies in collaboration with other Groups. Furthermore, the LCG promotes small phase II trials of new drugs or treatments for lung cancer and stimulates the investigation of new strategies and treatments for rare intrathoracic malignancies.

Chemotherapy for malignant mesothelioma: from doxorubicin to vinorelbine

It has been a challenge to find effective chemotherapeutic treatments for malignant mesothelioma. Over the last several decades numerous single-drug and combination regimens have been examined, but no standard treatment with chemotherapy alone has emerged. Possible explanations for this lack of success are the heterogeneity between the different subclasses of mesothelioma and the difficulties experienced in determining responses on computed tomographic (CT) scan. This review will present the results of most chemotherapy trials. An attempt is also been made to overcome the problem of identifying the overall response rate by presenting the median survival time. Other types of response evaluation and guidelines for patient selection are warranted to properly compare chemotherapeutic treatments.