Pleural mesothelioma: little evidence, still time to do trials

Four-Modality Therapy in Malignant Pleural Mesothelioma: A Phase II Study

BACKGROUND

Treatment approaches in malignant pleural mesothelioma (MPM) patients range from mere palliation to aggressive anticancer therapy, and there is currently no consensus on the optimal therapeutic strategy. In 1999, we began a phase II study to investigate four-modality treatment of advanced stage MPM.

METHODS

From 1999 to 2004, 49 patients with International Mesothelioma Interest Group stage II-III MPM underwent four-modality treatment with intrapleural preoperative interleukin-2 (18 x 10(6) UI/day for 3 days), pleurectomy/decortication, intrapleural postoperative epidoxorubicin (25 mg/m2 for 3 days), interleukin-2 (18 x 10(6) UI/day for 3 days), adjuvant radiotherapy (30 Gy), systemic chemotherapy (cisplatin 80 mg/m2 day 1, gemcitabine 1250 mg/m2 days 1 and 8 for up to six courses) and long-term subcutaneous interleukin-2 (3 x 10(6) UI/day on 3 days per week).

RESULTS

Patients included 41 men and eight women with a median age of 61 years (range, 41-77). All patients were diagnosed with MPM by thoracoscopy before inclusion. There was no postoperative mortality. Postoperative morbidity included bleeding (n = 1) and arrhythmias (n = 3). After a median follow-up of 59 months (range, 14-81), 13 patients are still alive and the median actuarial survival is 26 months (31 and 21 months for stages II and III, respectively). The 2- and 5-year actuarial survival rates were 60.2% and 23.3%, respectively. Baseline Eastern Cooperative Oncology Group performance status significantly influenced survival time (p = 0.02).

CONCLUSION

The four-modality treatment that we adopted for advanced-stage MPM was feasible, well tolerated by most of the patients, and produced a favorable median survival. This treatment approach warrants further investigation.

Preliminary data suggestive of a novel translational approach to mesothelioma treatment: imatinib mesylate with gemcitabine or pemetrexed

BACKGROUND

Malignant mesothelioma is a cancer which is refractory to current treatments. Imatinib mesylate is a selective inhibitor of tyrosine kinases such as bcr-abl, c-Kit, c-Fms and platelet derived growth factor receptor beta (PDGFRbeta). PDGFRbeta is often overexpressed in mesothelioma cells and is a therapeutic target for imatinib in some solid tumours. A study was undertaken to assess whether imatinib alone or combined with chemotherapeutic agents may be effective for treating mesothelioma.

METHODS

Cultures from mesothelioma MMP, REN and ISTMES2 cell lines were treated with imatinib alone or in combination with a chemotherapeutic agent.

RESULTS

Imatinib induced cytotoxicity and apoptosis selectively on PDGFRbeta positive mesothelioma cells via blockade of receptor phosphorylation and interference with the Akt pathway. Of the chemotherapeutic agents tested in combination with imatinib, a synergistic effect was obtained with gemcitabine and pemetrexed.

CONCLUSIONS

This study provides a rationale for a novel translational approach to the treatment of mesothelioma which relies on enhancement of tumour chemosensitivity by inhibition of Akt.

Pemetrexed as Second-Line Treatment in Malignant Pleural Mesothelioma after Platinum-Based First-Line Treatment

INTRODUCTION

Pemetrexed is active as first-line treatment of malignant pleural mesothelioma. The objective was to evaluate its activity as second-line treatment.

METHODS

Patients had disease progression of malignant pleural mesothelioma after previous platinum-based regimens without pemetrexed. Treatment was pemetrexed alone or pemetrexed combined with carboplatin. Pemetrexed dosing was 500 mg/m and carboplatin was AUC (area under the curve) 5 once every 3 weeks.

RESULTS

Thirty-nine patients were included: 28 Danish patients received pemetrexed (three patients received pemetrexed as third-line treatment), whereas 11 Norwegian patients received pemetrexed plus carboplatin. Most patients were men (90%), had epithelial subtype (85%), and International Mesothelioma Interest Group stages III to IV (77%). Median age was 62 years (range, 30-77). The median number of treatment courses was six (range, 1-23). Common Toxicity Criteria grade 3 to 4 toxicity occurred only with respect to leukocytopenia (pemetrexed: 14% of patients; pemetrexed plus carboplatin: 9%) and thrombocytopenia (pemetrexed: 7%; pemetrexed plus carboplatin: 18%). One patient receiving pemetrexed died of sepsis. Partial response rates were 21% and 18%, the median time to progression was 21 weeks (range, 4-92) and 32 weeks (range, 4-128+), and the median survival was 42 weeks (range, 4-99) and 39 weeks (range, 10-128+) with pemetrexed and pemetrexed plus carboplatin, respectively.

CONCLUSIONS

Pemetrexed was generally well tolerated with noteworthy activity in malignant pleural mesothelioma after previous platinum-based treatment and may be considered for second-line treatment.

Accuracy of pleural biopsy using thoracoscopy for the diagnosis of histologic subtype in patients with malignant pleural mesothelioma

BACKGROUND

Promising results with trimodality therapy combining surgery, chemotherapy, and radiotherapy have been obtained in the management of patients with malignant pleural mesothelioma (MPM). However, the histologic subtype has to be taken into account because of its influence on prognosis. The aim of the current study was to analyze retrospectively the accuracy, sensitivity, and specificity of preoperative thoracoscopy for diagnosis of the histologic subtype of MPM.

METHODS

The histologic reports from all consecutive patients undergoing 'intent-to-treat' surgery from 3 institutions as well as the initial pathologic diagnosis obtained using thoracoscopy were reviewed and compared after institutional review board approval. All cases of MPM were confirmed by a panel of pathologists.

RESULTS

Ninety-five patients were included in the current study. Of these 95 patients, 75 underwent extrapleural pneumonectomy, 9 patients underwent pleurectomy/decortication, and 11 patients underwent pleurectomy. Of the 95 patients with a final diagnosis of MPM, 80 (84.2%) were classified as having epithelial and 15 (15.8%) as having biphasic subtype. Among the 87 patients classified as having MPM of epithelial subtype after the initial thoracoscopy, 75 cases (86.2%) were confirmed to be a true histologic diagnosis and 12 cases (13.8%) were found to be of biphasic subtype at final diagnosis. One patient with a biphasic subtype at initial thoracoscopy was found to have MPM of epithelial subtype after surgery. The sensitivity and specificity values of an epithelial subtype diagnosis after thoracoscopy were 94% and 20%, respectively, with a positive predictive value of 86% and a negative predictive value of 37%. Conversely, the sensitivity and specificity values of a biphasic subtype diagnosis after thoracoscopy were 20% and 98%, respectively, with a positive predictive value of 75% and a negative predictive value of 87%.

CONCLUSIONS

Pleural biopsy performed using thoracoscopy is considered to be the cornerstone of the diagnosis and pleural staging of MPM. However, this procedure appears to be less efficient in diagnosing the histologic subtype as either epithelial or biphasic.

Heterogeneous nuclear ribonucleoprotein B1 expression in malignant mesothelioma

Heterogeneous nuclear ribonucleoprotein B1, an RNA-binding protein required for mRNA maturation, reportedly is overexpressed in early lung cancer and in several other tumors, including precancerous lesions. Expression of the protein was assessed immunohistochemically in 39 specimens of malignant mesothelioma and five of non-neoplastic pleura, and by flow cytometry in a human epithelioid mesothelioma cell line. No tumor showed overexpression, but 29 of 39 cases showed modest expression. Patients whose tumors showed expression had significantly better survival rates than others. Epithelioid tumors and reactive mesothelial cells were more likely to express the protein than sarcomatoid tumors and resting mesothelial cells. Flow cytometric analysis of an epithelioid mesothelioma cell line demonstrated stronger expression in exponentially growing than growth-restricted cells. Heterogeneous nuclear ribonucleoprotein B1 is expressed widely in malignant mesotheliomas and in reactive mesothelial cells, but is not overexpressed. This protein may regulate proliferation linked with differentiation toward epithelioid morphology in mesothelial cells. Expression of the protein may be a prognostic indicator for patents with malignant mesothelioma.

Human malignant mesothelioma: molecular mechanisms of pathogenesis and progression

The continuing identification and elucidation of the molecular defects involved in mesothelioma pathogenesis and progression should lead to better disease control and greater therapeutic options in the near future. Goal of this review article is to summarize the most recent advances in molecular pathogenesis of mesothelioma and discuss possible therapeutic implications of these findings.

Survival from rare cancer in adults: a population-based study

BACKGROUND

Rare cancers are a challenge to clinical practice, and treatment experience, even in major cancer centres to which rare cancers are usually referred, is often limited. We aimed to study the epidemiology of rare cancers in a large population of several countries.

METHODS

We analysed survival by age, sex, subsite, and morphology in 57,144 adults with 14 selected rare cancers diagnosed 1983-94. Variations in survival over time and between European regions were also assessed for variations in quality of care. We also estimated the adjusted relative excess risk of death for every rare cancer.

FINDINGS

Overall 5-year relative survival was good (ie, >65%) for placental choriocarcinoma (85.4% [95% CI 81.4-89.5]), thyroid medullary carcinoma (72.4% [69.2-75.5]), ovarian germ-cell cancer (73.0% [70.0-76.0]), lung carcinoid (70.1% [67.3-72.9]), and cervical adenocarcinoma (65.5% [64.3-66.6]); intermediate (ie, 35-65%) for testicular cancer at age 65 years or older (64.0% [59.3-68.7]), sarcoma of extremities (60.0% [58.9-61.2]), digestive-system endocrine cancers (55.6% [54.9-56.3]), anal squamous-cell carcinoma (53.1% [51.5-54.8]), and uterine sarcoma (43.5% [42.0-44.9]); low for carcinoma of adrenal-gland cortex (32.7% [28.3-37.2]) and bladder squamous-cell carcinoma (20.4% [18.8-22.0]); and poor for angiosarcoma of liver (6.4% [1.8-11.0]) and mesothelioma (4.7% [4.3-5.2]). Survival was usually better for women than men and poor in those aged 75 years or older. Survival significantly improved over time for ovarian germ-cell cancer, sarcomas of extremities, digestive-system endocrine tumours, anal squamous-cell carcinoma, and angiosarcoma of liver. Survival in northern Europe was higher than in the other geographic groupings for most cancers.

INTERPRETATION

Because effective treatments are available for several of the rare cancers we assessed, further research is needed to ascertain why survival is lower in some European countries than in others, particularly in older patients. Audit of best practice for rare cancers with treatment protocols would be useful.

Peritoneal mesothelioma treated by cytoreductive surgery and intraperitoneal hyperthermic chemotherapy: results of a prospective study

BACKGROUND

Peritoneal mesothelioma is a rare disease with few therapeutic options. Recently, the combination of cytoreductive surgery with intraperitoneal hyperthermic chemotherapy (HIPEC) has shown promising results.

METHODS

Fifteen patients with peritoneal mesothelioma who were treated by cytoreductive surgery and HIPEC between 1989 and 2004 were identified from a prospective database. HIPEC was performed with cisplatin and mitomycin C for 90 minutes by using the closed-abdomen technique.

RESULTS

All patients but one (multicystic) had malignant disease of the following pathologic types: 12 epithelial and 2 biphasic. After surgical resection, 11 patients were considered to have a CC-0 or CC-1 resection (macroscopic complete resection or diameter of residual nodules <2.5 mm). No postoperative death occurred, and six postoperative complications were recorded. All but one patient had resolution of ascites. The overall median survival for the 14 patients with malignant mesothelioma was 35.6 months. The median survival was 37.8 months for patients treated with a CC-0 or CC-1 resection, whereas it was 6.5 months for those treated with a CC-2 or CC-3 resection (diameter of residual nodules >2.5 mm; P < .001). In a univariate analysis, the only other significant prognostic factor was the carcinomatosis extent (P = .02).

CONCLUSIONS

A therapeutic strategy combining cytoreductive surgery with HIPEC seems to provide an adequate and efficient locoregional treatment for peritoneal mesothelioma. It is associated with acceptable morbidity when performed by an experienced surgical team. The completeness of cytoreduction is the major determinant of survival.

Human neoplastic mesothelial cells express voltage-gated sodium channels involved in cell motility

Given the pivotal role of ion channels in neoplastic transformation, the aim of the present study has been to assess possible differences in the expression patterns of voltage-gated monovalent cationic (Na(+) and K(+)) currents between normal and neoplastic mesothelial cells (NM, MPM, respectively), and to evaluate the role of specific ion channels in mesothelioma cells proliferation, apoptosis, and motility. To achieve this aim, membrane currents expressed in NM and MPM cells derived from surgically-removed human specimens were investigated by means of patch-clamp electrophysiology. NM cells were found to express three main classes of K(+) currents, which were defined as K(IR), maxiK(Ca), and K(V) currents on the basis of their biophysical and pharmacological properties. Each of these K(+) currents was absent in MPM cells; by contrast, MPM cells revealed the novel appearance of tetrodotoxin (TTX)-sensitive voltage-gated Na(+) currents undetected in normal mesothelial cells. Reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time PCR analysis of MPM cells transcripts showed significant expression of the mRNAs encoding for Na(V)1.2, and Na(V)1.6, and Na(V)1.7 (and less so for Na(V)1.3, Na(V)1.4, and Na(V)1.5) main voltage-gated sodium channel (VGSC) alpha-subunit(s). Interestingly, blockade of VGSCs with TTX decreased mesothelioma cell migration in in vitro motility assays; on the other hand, TTX failed to interfere with cell viability, proliferation, and apoptosis progression triggered by UV exposure. In summary, the results of the present study suggest that VGSCs expression in MPM cells may favor the increased motility of the neoplastic cells, a phenotypic feature often associated with the malignant phenotype.

EGFR overexpression in malignant pleural mesothelioma. An immunohistochemical and molecular study with clinico-pathological correlations

The epidermal growth factor receptor (EGFR) is overexpressed in many epithelial malignancies, against which some antitumoral drugs have been developed. There is a lack of information as to EGFR expression in malignant pleural mesothelioma (MPM), an aggressive and fatal cancer poorly responsive to current oncological treatments. Our aim was to: (a) compare EGFR immunohistochemical expression with mRNA levels measured by real time PCR; (b) assess the relationships between EGFR expression and clinico-pathological data including survival; (c) analyze the EGFR mutations. We developed an immunohistochemical method of EGFR evaluation based on the number of immunoreactive cells and staining intensity in 61 MPMs. EGFR immunoreactivity was documented in 34/61 (55.7%) cases. A significant correlation between EGFR protein and mRNA levels (p = 0.0077) was found, demonstrating the reliability of our quantification method of EGFR membrane expression. Radically resected patients (p = 0.005) and those with epithelial histotype (p = 0.048) showed an increased survival. No statistical correlation between EGFR immunoreactivity and patients survival was observed. No EGFR mutation was documented. This study documents EGFR overexpression in MPM at the protein and the transcriptional levels; it proposes a reliable method for EGFR expression evaluation in MPM. EGFR levels are not associated with clinico-pathological features of patients, including survival.

Mesothelioma from the Patient's Perspective

This study reports findings from qualitative semi-structured interviews with 15 patients who suffered from mesothelioma. The results are described under four headings that reflect the main themes that arose from the data: coping with symptoms (particularly breathlessness and pain), finding out about mesothelioma and its implications, the trauma of medical interventions, and psychosocial issues. The results illustrate the severe disease burden that is borne by people who have mesothelioma. It is hoped that a greater understanding of mesothelioma from a patient's perspective could inform the response of health care professionals.

Detection of Malignant Mesothelioma in Asbestos-Exposed Individuals: The Potential Role of Soluble Mesothelin-Related Protein

Malignant mesothelioma (MM) is strongly associated with asbestos exposure. Measurement of soluble mesothelin-related protein (SMRP) levels in the serum may prove valuable as an adjunct to current tests for the diagnosis of MM and for monitoring MM patients for the early detection of disease recurrence. SMRP measures also may be useful in an overall screening program for MM because early results show that some individuals have elevated levels 1 to 4 years before symptom development. Although individuals with occupational and nonoccupational asbestos exposure are justifiably concerned about their risk of developing MM, consideration must be given to the complex issues surrounding screening for this disease, and a more substantial evaluation of the SMRP marker must be undertaken before deciding to promote a screening program.

Management of malignant pleural effusions

PURPOSE OF REVIEW

Although malignant pleural effusions are a common medical problem, research into their optimal management remains sparse. The aim of this review is to summarise recent developments in this area.

RECENT FINDINGS

Talc remains the most efficacious pleurodesis agent. However, concerns remain about its side effect profile, with a number of cases of acute respiratory distress syndrome documented in the literature. A recent trial showed that using calibrated talc particles reduced the risk of morbidity from this procedure. Work on novel pleurodesis agents, such as transforming growth factor-beta, appears to induce pleurodesis in animal models without any unwanted side effects. This is a promising development and human trials are awaited. With regard to mesothelioma, recent chemotherapy trials with pemetrexed/cisplatin and raltitrexed/cisplatin are encouraging and appear, for the first time, to offer a small but real survival advantage.

SUMMARY

In the authors' opinion, the major developments in the management of malignant effusions during the past year are the development of safer pleurodesis agents and the promise of better combination chemotherapy agents for the treatment of mesothelioma.

Palliative intracavitary carboplatin therapy in a cat with suspected pleural mesothelioma

A 12-year-old neutered male oriental shorthair cat was referred to the Animal Health Trust for investigation of pleural effusion. Ultrasonography revealed marked irregular thickening of the pleural surface of the cranial and caudal mediastinum. Cytological examination of the pleural fluid and fine needle aspirates of the thickened pleura suggested a diagnosis of mesothelioma. Following complete drainage of the thoracic cavity under ultrasound guidance, 180 mg/m2 carboplatin diluted in 60 ml sterile water was infused into the pleural space (30 ml in each hemithorax). This resulted in complete resolution of clinical signs for 34 days (having required thoracocentesis on four occasions in the preceding 4 weeks). The procedure was repeated using 200 mg/m2 carboplatin, and there was a further 20-day period where the cat was free of clinical signs. Further treatment was declined and the cat was euthanased 120 days after initial presentation. This is the first report of successful palliative chemotherapy for suspected feline mesothelioma and suggests that intracavitary carboplatin could be considered in tumours affecting the pleural cavity.

A novel in vitro model of human mesothelioma for studying tumor biology and apoptotic resistance

Like many tumors, malignant mesothelioma exhibits significant chemoresistance and resistance to apoptosis in vivo that is not seen in current in vitro models. To study the mechanisms of this multicellular resistance, biologically relevant in vitro models are necessary. Therefore, we characterized and tested human mesothelioma tissue grown in vitro as tumor fragment spheroids. After 5-10 d in culture, fragments from each of 15 human mesothelioma tumors rounded into spheroids. The tumor fragment spheroids maintained multiple characteristics of the original tumors for up to 3 mo including the presence of viable mesothelioma cells, macrophages, and a collagen-rich stroma. In 14-d-old spheroids, mesothelioma cells showed the same proliferation rate and expression of a death receptor, DR5, as in the original tumor. To determine responses to treatment, we treated tumor fragment spheroids grown from three separate tumors with agents, TNF-related apoptosis-inducing ligand (TRAIL) plus cycloheximide, that induced near total apoptosis in three human mesothelioma cell lines (M28, REN, MS-1) grown as monolayers (94 +/- 6% apoptosis; mean +/- SEM). Compared with mesothelioma cells in monolayers, mesothelioma cells in the spheroids were resistant to TRAIL plus cycloheximide (32 +/- 4% apoptosis; mean +/- SEM). Apoptotic resistance of mesothelioma cells was significantly reduced by inhibiting either the PI3K/Akt pathway with LY294002 (47 +/- 6% apoptosis) or the mTOR pathway with rapamycin (50 +/- 17% apoptosis). We conclude that human mesothelioma can be maintained in vitro in a biologically relevant model that exhibits apoptotic resistance, thereby permitting study of its tumor biology and of novel approaches to therapy.

Malignant mesothelioma

Malignant mesothelioma is an aggressive, treatment-resistant tumour, which is increasing in frequency throughout the world. Although the main risk factor is asbestos exposure, a virus, simian virus 40 (SV40), could have a role. Mesothelioma has an unusual molecular pathology with loss of tumour suppressor genes being the predominant pattern of lesions, especially the P16INK4A, and P14ARF, and NF2 genes, rather than the more common p53 and Rb tumour suppressor genes. Cytopathology of mesothelioma effusions or fine-needle aspirations are often sufficient to establish a diagnosis, but histopathology is also often required. Patients typically present with breathlessness and chest pain with pleural effusions. Median survival is now 12 months from diagnosis. Palliative chemotherapy is beneficial for mesothelioma patients with high performance status. The role of aggressive surgery remains controversial and growth factor receptor blockade is still unproven. Gene therapy and immunotherapy are used on an experimental basis only. Patterns identified from microarray studies could be useful for diagnosis as well as prognostication.

Immunotherapy of Murine Malignant Mesothelioma Using Tumor Lysate–pulsed Dendritic Cells

RATIONALE

Exploiting the immunostimulatory capacities of dendritic cells holds great promise for cancer immunotherapy. Currently, dendritic cell-based immunotherapy is evaluated clinically in a number of malignancies, including melanoma and urogenital and lung cancer, showing variable but promising results.

OBJECTIVE

To evaluate if pulsed dendritic cells induce protective immunity against malignant mesothelioma in a mouse model.

METHODS

Malignant mesothelioma was induced in mice by intraperitoneal injection of the AB1 mesothelioma cell line, leading to death within 28 days. For immunotherapy, dendritic cells were pulsed overnight either with AB1 tumor cell line lysate, AB1-derived exosomes, or ex vivo AB1 tumor lysate, and injected either before (Days -14 and -7) at the day of (Day 0) or after (Days +1 and +8) tumor implantation.

MAIN RESULTS

Mice receiving tumor lysate-pulsed dendritic cells before tumor implantation demonstrated protective antitumor immunity with prolonged survival (> 3 months) and even resisted secondary tumor challenge. Tumor protection was associated with strong tumor-specific cytotoxic T-lymphocyte responses. Adoptive transfer of splenocytes or purified CD8+ T lymphocytes transferred tumor protection to unimmunized mice in vivo. When given after tumor implantation in a therapeutic setting, pulsed dendritic cells prevented mesothelioma outgrowth. With higher tumor load and delayed administration after tumor implantation, dendritic cells were no longer effective.

CONCLUSIONS

We demonstrate in this murine model that immunotherapy using pulsed dendritic cells may emerge as a powerful tool to control mesothelioma outgrowth. In the future, immunotherapy using dendritic cells could be used as adjuvant to control local recurrence after multimodality treatment for malignant mesothelioma.

Current chemotherapeutic treatment of malignant pleural mesothelioma

Malignant pleural mesothelioma is an aggressive malignancy which is almost always fatal; median survival is usually < 1 year. Most patients present with symptoms including pain, dyspnoea, pleural effusions and chest wall masses. Until recently, there has been no effective treatment which can improve symptoms and prolong survival. This article reviews recent developments in the treatment of mesothelioma, particularly advances in drug therapy and the use of the current most active drug combination: pemetrexed and cisplatin. Pemetrexed is a novel antifolate drug with multiple enzyme targets. The combination of pemetrexed and cisplatin demonstrated a survival advantage over cisplatin alone in patients with pleural mesothelioma, and can give symptomatic benefits. This combination has become the standard of care in mesothelioma treatment.