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

Contemporary issues in the surgical management of pleural mesothelioma

The surgical management of pleural mesothelioma (PM) can be divided into diagnostic, staging, palliation, and cytoreductive surgery. In the cytoreductive surgical setting, the combination of different treatment modalities has led to better outcomes than surgery alone. The scarcity of high-quality studies has led to heterogeneity in management of PM across the mesothelioma treatment centers. Here, we review the literature regarding the most important open questions and ongoing clinical trials.

An RNAi therapeutic, DFP-10825, for intraperitoneal and intrapleural malignant cancers

RNA interference (RNAi), a potent post-transcriptional gene-silencing action, has received considerable attentions as a novel therapeutic tool to treat intractable cancers. In recent days, we have developed a novel RNAi-based therapeutic formulation, DFP-10825, for the treatment of intractable advanced cancers developed in coelomic cavities. DFP-10825 was composed of chemically synthesized short hairpin RNA (shRNA) against thymidylate synthase (TS), a key enzyme for cancer proliferation, and cationic liposomes, and achieved high therapeutic effect on the mouse models of peritoneally disseminated gastric and ovarian cancers and malignant pleural mesothelioma without severe side effects by intracoelomic direct treatment. We further designed a freeze-dried DFP-10825 formulation for mass industrial production. DFP-10825 is undergoing in pre-clinical phase and goes to clinical trials. This review introduces a DFP-10825 formulation, a potent novel RNAi-based therapeutic maximizing the benefit of RNAi molecule (shRNA).

Combining immunotherapy with radiation therapy in thoracic oncology

Thoracic malignancies comprise some of the most common and deadly cancers. Immunotherapies have been proven to improve survival outcomes for patients with advanced non-small cell lung cancer (NSCLC) and show great potential for patients with other thoracic malignancies. Radiation therapy (RT), an established and effective treatment for thoracic cancers, has acted synergistically with immunotherapies in preclinical studies. Ongoing clinical trials are exploring the clinical benefits of combining RT with immunotherapies and the optimal manner in which to deliver these complementary treatments.

Downregulation of thymidylate synthase by RNAi molecules enhances the antitumor effect of pemetrexed in an orthotopic malignant mesothelioma xenograft mouse model

Malignant pleural mesothelioma (MPM) is an incurable cancer with an increasing incidence. Currently, pemetrexed (PMX)-based chemotherapy is the mainstay of chemotherapy for MPM, however, the outcome of PMX-based chemotherapy in patients with MPM is dismal. RNA interference (RNAi) technology has been considered as an effective tool to substantially enhance the therapeutic efficacy of chemotherapeutic agents in many preclinical and clinical settings. In this study, therefore, we investigated whether non-viral anti-thymidylate synthase RNAi embedded liposome (TS shRNA lipoplex) would effectively guide the downregulation of TS in human malignant mesothelioma MSTO-211H cells. Consequently, it enhanced the antitumor effect of PMX both in vitro and in vivo. TS shRNA effectively enhanced the in vitro cell growth inhibition upon treatment with PMX via downregulating TS expression in the MSTO-211H cell line. In in vivo orthotopic tumor model, the combined treatment of PMX and TS shRNA lipoplex efficiently combated the progression of orthotopic thoracic tumors and as a result prolonged mouse survival, compared to each single treatment. Our findings emphasize the pivotal relevance of RNAi as an effective tool for increasing the therapeutic efficacy of PMX, a cornerstone in the treatment regimens of MPM, and thereby, raising the possibility for the development of a novel therapeutic strategy, combination therapy of TS-shRNA and PMX, that can surpass many of the currently applied, but less effective, therapeutic regimens against lethal MPM.

Differential expression of extracellular matrix constituents and cell adhesion molecules between malignant pleural mesothelioma and mesothelial hyperplasia

INTRODUCTION

Malignant pleural mesothelioma (MPM) is a highly aggressive neoplasm associated with asbestos exposure. Currently, the molecular mechanisms that induce MPM development are still unknown. The purpose of this study was to identify new molecular biomarkers for mesothelial carcinogenesis.

METHODS

We analyzed a panel of 84 genes involved in extracellular matrix remodeling and cell adhesion by polymerase chain reaction (PCR) array in 15 samples of epithelioid mesothelioma and 10 samples of reactive mesothelial hyperplasia (MH; 3 of 25 samples were inadequate for mRNA analysis). To validate the differentially expressed genes identified by PCR array, we analyzed 27 more samples by immunohistochemistry, in addition to the 25 samples already studied.

RESULTS

Twenty-five genes were differentially expressed in MPM and MH by PCR array. Of these we studied matrix metalloproteinase 7 (MMP7), MMP14, CD44, and integrin, alpha3 expression by immunohistochemistry in 26 epithelioid MPM and 26 MH samples from the entire series of 52 cases. We observed higher MMP14 and integrin, alpha3 expression in MPM samples compared with MH samples (p = 0.000002 and p = 0.000002, respectively). Conversely, CD44 expression was low in most (57.7%) mesothelioma samples but only in 11.5% of the MH samples (p = 0.0013). As regards MMP7, we did not observe differential expression between MH and MPM samples.

CONCLUSIONS

We have extensively studied genes involved in cell adhesion and extracellular matrix remodeling in MPM and MH samples, gaining new insight into the pathophysiology of mesothelioma. Moreover, our data suggest that these factors could be potential biomarkers for MPM.

Immune responses and immunotherapeutic interventions in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive, primary pleural malignancy with poor prognosis, hypothesized to originate from a chronic inflammatory state within the pleura. Similar to what has been observed in other solid tumors (melanoma, ovarian and colorectal cancer), clinical and pre-clinical MPM investigations have correlated anti-tumor immune responses with improved survival. As such, a better understanding of the complex MPM tumor microenvironment is imperative in strategizing successful immunotherapies. Herein, we review the immune responses vital to the development and progression of MPM, as well as assess the role of immunomodulatory therapies, highlighting recent pre-clinical and clinical immunotherapy investigations.

Novel targeted therapies and vaccination strategies for mesothelioma

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

What is the role of radiotherapy in malignant pleural mesothelioma?

OBJECTIVE

A review of the evidence supporting the use of radiotherapy in patients with mesothelioma was performed.

METHODS

Relevant publications were searched for on Medline.

RESULTS

In a Medline search on radiotherapy and mesothelioma, 611 hits were obtained. A limited number of prospective phase II trials of radiotherapy as part of trimodality protocols for early disease and in the palliation of pain were found, along with three small randomized controlled trials of port-site prophylaxis.

CONCLUSION

No randomized data exist to support the use of radiotherapy after radical surgery, although there are a large number of publications describing its use as an integral part of therapy, including seven phase II studies. One ongoing trial is randomizing patients to radiotherapy or not after extrapleural pneumonectomy. None of these studies provided any assessment of radiotherapy independent of the other modalities investigated, nor did any formally assess intensity-modulated radiotherapy. There have been several reports of excessive toxicity with this technique, and its use should be limited to phase I studies until the basis of this toxicity is better understood. Three trials have looked at port-site prophylaxis, one supporting its use and two showing no evidence of benefit. Two studies addressed pain control prospectively, one showing definite but short-lived benefits. Implications. Radiotherapy is widely used in treating mesothelioma with little supporting evidence. More randomized trials are required to justify this use in all three common settings for its use.

A systematic review of lung-sparing extirpative surgery for pleural mesothelioma

OBJECTIVES

There is a resurgence of interest in lung-sparing extirpative surgery for malignant pleural mesothelioma with recent reports of better survival and fewer adverse consequences than with extrapleural pneumonectomy. However, these operations are not well-characterized and to offer evidence-based clinical recommendations and to plan future trials a summary of what is already known is required.

DESIGN

A formal literature search was performed and all recovered titles were sequentially sifted by title, abstract and full-text reading according to prespecified criteria. Papers were selected if they contained data relevant to the area of enquiry. Quantitative synthesis and textual analysis, appropriate to the material, were performed.

SETTING

Follow-up studies of patients undergoing surgery for malignant pleural mesothelioma in specialist thoracic or cardiothoracic units.

PARTICIPANTS

Among the operated patients described in these papers, a total of 1270 patients had undergone lung-sparing surgery for mesothelioma.

RESULTS

There were no randomized trials or other forms of controlled studies. From 464 titles, 26 papers contained sufficient data on 1270 patients to be included in the systematic review. Operative descriptions for all series were extracted and tabulated and variation was found in the nature of surgery within and between series, and the degree of detail with which it was described. There was more operative detail in recent papers. All available numerical data were extracted, tabulated and summarized using quantitative methods. The average survival at 1, 2, 3, 4 and 5 years was 51%, 26%, 16%, 11% and 9%, respectively. There were no data on patients' performance status, symptomatic change, or other patient reported outcomes.

CONCLUSIONS

In the absence of any form of control data, no conclusions can be drawn concerning survival differences or symptomatic benefits attributable to surgery. As mesothelioma surgery is restricted to a selected minority of patients who often have multiple therapies, future research will require controlled studies with explicit definitions of the clinical and surgical intent.

Treatment with interleukin-2 in malignant pleural mesothelioma: immunological and angiogenetic assessment and prognostic impact

Background:

Administration of interleukin-2 (IL-2) has shown some effects on malignant pleural mesothelioma (MPM) tumour regression. The purpose of this study was to investigate the ability of IL-2 to modify immunological effector cells and angiogenesis in MPM patients and their prognostic value.

Methods:

Tumour-infiltrating lymphocytes (CD4, CD8, Foxp3), mast cells (MCs) (tryptase and chymase), microvessel count (MVC) and VEGF were determined by immunohistochemistry in two series of MPM patients: 60 patients treated with intra-pleural preoperative IL-2 and 33 patients untreated.

Results:

Tryptase MCs, and CD8 and Foxp3 lymphocytes were significantly increased in the IL-2-treated group, whereas MVC was significantly lower in the same group. Moreover, in the IL-2-treated group, greater tryptase+MCs and greater Foxp3 lymphocytes were associated with improved and poorer clinical outcomes, respectively. Notably, when these two immunological parameters were combined, they predicted outcomes more effectively.

Conclusions:

This study showed that IL-2 treatment leads to a significant increase of immunological parameters, concomitantly with a reduction in vasculature, providing new insight into the cancer mechanisms mediated by IL-2. Moreover, these results suggest that tryptase-positive MCs and Foxp3+ lymphocytes predict clinical outcomes in IL-2-treated patients, highlighting the critical role of the inflammatory response in mesothelioma cancer progression.

Tryptase mast cells in malignant pleural mesothelioma as an independent favorable prognostic factor

INTRODUCTION

Malignant pleural mesothelioma is a highly aggressive neoplasm with an incidence that is increasing world-wide. Mast cells are part of the innate immune system and have been associated with different solid tumors, but there is controversy surrounding their pro- and antitumorigenic effects in cancers. There are two subsets of human mast cells, resulting from the expression of different enzymes: tryptase positive mast cells and chymase positive mast cells. The purpose of this study was to determine the presence and prognostic significance of tumor infiltrating mast cells in mesothelioma.

METHODS

Tryptase and chymase mast cell counts were determined by immunohistochemistry in 60 patients with mesothelioma. All pathologic samples were from patients who underwent treatment with intrapleural preoperative interleukin-2 (18 x 10(6) IU/d for 3 days). After one day of recovery, patients underwent surgery. Pleural samples were also immunostained for CD34 to evaluate microvessel count.

RESULTS

High tryptase mast cells counts were found in the majority (73.3%) of the cases studied, and the results were significantly associated with both overall survival (p = 0.02) and time to progression (p = 0.01). This finding was confirmed using multivariate analysis: a higher tryptase mast cells count emerged as an independent favorable prognostic factor (p = 0.02). However, tryptase mast cells count did not show significant correlation with microvessel count.

CONCLUSIONS

These results suggest that tumor infiltrating tryptase mast cells, after interleukin-2 preoperative induction therapy, predict improved clinical outcome in patients with malignant pleural mesothelioma, and highlight the critical role of the local inflammatory response in mesothelioma cancer progression.

Treatment of malignant pleural mesothelioma with carboplatin, liposomized doxorubicin, and gemcitabine: a phase II study

BACKGROUND

Malignant pleural mesothelioma has a poor prognosis and there is limited effect of treatment. The Nordic Mesothelioma groups decided in the year 2000 to investigate a combination of liposomized doxorubicin, carboplatin, and gemcitabine for this disease in a phase II study.

METHODS

From January 2001, to December 2003, 173 evaluable patients with biopsy-verified malignant mesothelioma were included. Two patients were lost to follow-up, but all the others were followed for at least 4 years or until death.

RESULTS

Toxicity was fairly low. There were 56 responses (32.4%), of which 2 were complete; the median time to progression was 8.6 months, and the median overall survival was 13 months. Some patients had their responses 4 to 6 months after last treatment. For 116 patients with epitheloid subtype, median survival was 17 months. A subgroup of these patients with good performance status, early stage, and age 70 years or less, showed a median survival of 22 months.

CONCLUSION

The treatment yields good results with a high number of responses and long survival, and a low toxicity. The long survival of the epitheloid subgroup with good prognostic factors is as good as or even better than some studies on "radical" surgery or multimodal treatment, underlining the need of randomized studies to evaluate such treatment options.

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

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

Immunotherapy and radiation therapy for malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a particularly aggressive thoracic malignancy with limited survival following combination chemotherapy. As a result, there has been increased interested in immunotherapy for mesothelioma, both in the first-line and salvage settings. Early investigations of interleukin-2 (IL-2) and interferon alfa-2a/b have been limited by modest response rates and toxicity, whereas cytokine gene therapy is currently being investigated and shows early promise. The most prominent class of immunotherapies to be trialed with mesothelioma in the past half-decade has been immune checkpoint inhibitors (CPI). Early results are encouraging, particularly for agents targeting the PD-1/PD-L1 pathways. With the increasing recognition of the immune potential of mesothelioma, interest in the immunomodulatory properties of radiation therapy has emerged. The combination of immunotherapy and radiation therapy may allow for complimentary immunologic effects that can enhance antitumor response. This article reviews the existing literature on the efficacy of immunotherapy for MPM, describes the rationale for combining immunotherapy with radiation therapy, and discusses early literature on this treatment combination.

Radiotherapy for malignant pleural mesothelioma

BACKGROUND

Malignant pleural mesothelioma is a relatively uncommon disease, but the incidence is increasing and is expected to peak in many developed countries in the next two decades. The management of patients with malignant mesothelioma is controversial. Very few patients are suitable for any potentially curative treatment and the effectiveness of radical therapy with surgery, radiotherapy and/or chemotherapy in curing patients or prolonging survival is uncertain. The role of radiotherapy is controversial although it has been used as part of multimodal therapy. The present review will try to clarify these uncertainties.

OBJECTIVES

To assess the effectiveness and safety of radiotherapy on patients with malignant pleural mesothelioma in any stage of the disease.

SEARCH STRATEGY

Both electronic and handsearches were conducted. All randomised controlled clinical trials were searched in electronic databases such as: Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE. Handsearching was aimed at the identification of evidence by reviewing journals not indexed in databases, proceedings of conferences and/or scientific meetings.

SELECTION CRITERIA

All randomised controlled clinical trials using radiotherapy for malignant pleural mesothelioma in any stage, alone or combined with other therapies in patients of either sex and any age, were included. Studies without a control group were excluded.

DATA COLLECTION AND ANALYSIS

There were no studies that fulfilled the inclusion criteria.

MAIN RESULTS

To date we have not found any reports of randomised comparisons of radiotherapy alone or combined for patients with malignant pleural mesothelioma.

AUTHORS' CONCLUSIONS

As radiotherapy has never been compared to chemotherapy or surgery or to best supportive care (as part of combination therapy) in a prospective, randomised trial, no data exist supporting one or the other treatment as a better option for patients with malignant pleural mesothelioma. There is a need for multicentre controlled randomised trials assessing the role of radiotherapy in the radical treatment of malignant pleural mesothelioma. The studies should be limited to patients with malignant pleural mesothelioma, classified by stage, cytology and type of radiotherapy. The type of radiotherapy should be defined in advance and variables of radiotherapy dose definition and delivery should be carefully controlled.