A trial of intrapleural adenoviral-mediated Interferon-α2b gene transfer for malignant pleural mesothelioma

Biomimetic Nucleic Acid Drug Delivery Systems for Relieving Tumor Immunosuppressive Microenvironment

Immunotherapy combats tumors by enhancing the body's immune surveillance and clearance of tumor cells. Various nucleic acid drugs can be used in immunotherapy, such as DNA expressing cytokines, mRNA tumor vaccines, small interfering RNAs (siRNA) knocking down immunosuppressive molecules, and oligonucleotides that can be used as immune adjuvants. Nucleic acid drugs, which are prone to nuclease degradation in the circulation and find it difficult to enter the target cells, typically necessitate developing appropriate vectors for effective in vivo delivery. Biomimetic drug delivery systems, derived from viruses, bacteria, and cells, can protect the cargos from degradation and clearance, and deliver them to the target cells to ensure safety. Moreover, they can activate the immune system through their endogenous activities and active components, thereby improving the efficacy of antitumor immunotherapeutic nucleic acid drugs. In this review, biomimetic nucleic acid delivery systems for relieving a tumor immunosuppressive microenvironment are introduced. Their immune activation mechanisms, including upregulating the proinflammatory cytokines, serving as tumor vaccines, inhibiting immune checkpoints, and modulating intratumoral immune cells, are elaborated. The advantages and disadvantages, as well as possible directions for their clinical translation, are summarized at last.

Leveraging the pleural space for anticancer therapies in pleural mesothelioma

Most patients with pleural mesothelioma (PM) present with symptomatic pleural effusion. In some patients, PM is only detectable on the pleural surfaces, providing a strong rationale for intrapleural anticancer therapy. In modern prospective studies involving expert radiological staging and specialist multidisciplinary teams, the population incidence of stage I PM (an approximate surrogate of pleura-only PM) is higher than in historical retrospective series. In this Viewpoint, we advocate for the expansion of intrapleural trials to serve these patients, given the paucity of data supporting licensed systemic therapies in this setting and the uncertainties involved in surgical therapy. We begin by reviewing the unique anatomical and physiological features of the PM-bearing pleural space, before critically appraising the evidence for systemic therapies in stage I PM and previous intrapleural PM trials. We conclude with a summary of key challenges and potential solutions, including optimal trial designs, repurposing of indwelling pleural catheters, and new technologies.

Contemporary management of mesothelioma

Pleural mesothelioma (PM) is an aggressive asbestos-associated thoracic malignancy with a median survival of 12-18 months. Due to continued asbestos use in many nations, global incidence is rising. Causes due to non-occupational, environmental exposure are also rising in many countries despite utilisation bans. For many years, platinum--pemetrexed chemotherapy was the solitary licensed therapy, but first-line combination immune checkpoint blockade has recently demonstrated improved outcomes, with both regimes tested in predominantly late-stage cohorts. In the second-line setting, single-agent nivolumab has been shown to extend survival and is now available for routine use in some regions, while second-line chemotherapy has no proven role and opportunities for clinical trials should be maximised in relapsed disease. Surgery for "technically resectable" disease has been offered for decades in many expert centres, but the recent results from the phase III MARS2 trial have challenged this approach. There remains no robustly proven standard of care for early-stage PM. The clinical trial landscape for PM is complex and increasingly diverse, making further development of specialist PM multidisciplinary teams an important priority in all countries. The observation of improving outcomes in centres that have adopted this service model emphasises the importance of high-quality diagnostics and equitable access to therapies and trials. Novel therapies targeting a range of aberrations are being evaluated; however, a better understanding of the molecular drivers and their associated vulnerabilities is required to identify and prioritise treatment targets.

Intrapleural Anticancer Therapy for Malignant Pleural Diseases: Facts or Fiction?

Malignant pleural diseases involves both primary pleural malignancies (e.g., mesothelioma) as well as metastatic disease involving the pleura. The management of primary pleural malignancies remains a challenge, given their limited response to conventional treatments such as surgery, systemic chemotherapy, and immunotherapy. In this article, we aimed to review the management of primary pleural malignancy as well as malignant pleural effusion and assess the current state of intrapleural anticancer therapies. We review the role intrapleural chemotherapy, immunotherapy, and immunogene therapy, as well as oncolytic viral, therapy and intrapleural drug device combination. We further discuss that while the pleural space offers a unique opportunity for local therapy as an adjuvant option to systemic therapy and may help decrease some of the systemic side effects, further patient outcome-oriented research is needed to determine the exact role of these treatments within the armamentarium of currently available options.

Correlative analysis from a phase I clinical trial of intrapleural administration of oncolytic vaccinia virus (Olvi-vec) in patients with malignant pleural mesothelioma

Background

The attenuated, genetically engineered vaccinia virus has been shown to be a promising oncolytic virus for the treatment of patients with solid tumors, through both direct cytotoxic and immune-activating effects. Whereas systemically administered oncolytic viruses can be neutralized by pre-existing antibodies, locoregionally administered viruses can infect tumor cells and generate immune responses. We conducted a phase I clinical trial to investigate the safety, feasibility and immune activating effects of intrapleural administration of oncolytic vaccinia virus (NCT01766739).

Methods

Eighteen patients with malignant pleural effusion due to either malignant pleural mesothelioma or metastatic disease (non-small cell lung cancer or breast cancer) underwent intrapleural administration of the oncolytic vaccinia virus using a dose-escalating method, following drainage of malignant pleural effusion. The primary objective of this trial was to determine a recommended dose of attenuated vaccinia virus. The secondary objectives were to assess feasibility, safety and tolerability; evaluate viral presence in the tumor and serum as well as viral shedding in pleural fluid, sputum, and urine; and evaluate anti-vaccinia virus immune response. Correlative analyses were performed on body fluids, peripheral blood, and tumor specimens obtained from pre- and post-treatment timepoints.

Results

Treatment with attenuated vaccinia virus at the dose of 1.00E+07 plaque-forming units (PFU) to 6.00E+09 PFU was feasible and safe, with no treatment-associated mortalities or dose-limiting toxicities. Vaccinia virus was detectable in tumor cells 2-5 days post-treatment, and treatment was associated with a decrease in tumor cell density and an increase in immune cell density as assessed by a pathologist blinded to the clinical observations. An increase in both effector (CD8+, NK, cytotoxic cells) and suppressor (Tregs) immune cell populations was observed following treatment. Dendritic cell and neutrophil populations were also increased, and immune effector and immune checkpoint proteins (granzyme B, perforin, PD-1, PD-L1, and PD-L2) and cytokines (IFN-γ, TNF-α, TGFβ1 and RANTES) were upregulated.

Conclusion

The intrapleural administration of oncolytic vaccinia viral therapy is safe and feasible and generates regional immune response without overt systemic symptoms.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/NCT01766739, identifier NCT01766739.

Seroprevalence of Binding and Neutralizing Antibodies against 39 Human Adenovirus Types in Patients with Neuromuscular Disorders

High pre-existing antibodies against viral vectors reduce their functionality and may lead to adverse complications. To circumvent this problem in future gene therapy approaches, we tested the seroprevalence of a large range of human adenovirus types in patients with neuromuscular disorders (NMDs) to find appropriate viral vector candidates for gene replacement therapy for NMDs. Binding and neutralizing antibodies against 39 human adenovirus types were tested in the sera of 133 patients with NMDs and 76 healthy controls aged 17-92 years. The influence of age, sex, and NMDs on antibody levels was analyzed. The seroprevalence of different adenoviruses in the cohort varied widely. The highest levels of binding antibodies were detected against HAdV-D27, -C1, -D24, -D70, -B14, -C6, -D13, -B34, and -E4, whereas the lowest reactivity was detected against HAdV-F41, -A31, -B11, -D75, -D8, -D65, -D26, -D80, and -D17. The highest neutralizing reactivity was observed against HAdV-B3, -C2, -E4, -C1, -G52, -C5, and -F41, whereas the lowest neutralizing reactivity was observed against HAdV-D74, -B34, -D73, -B37, -D48, -D13, -D75, -D8, -B35, and -B16. We detected no influence of sex and only minor differences between different age groups. Importantly, there were no significant differences between healthy controls and patients with NMDs. Our data show that patients with NMDs have very similar levels of binding and neutralizing antibodies against HAdV compared to healthy individuals, and we identified HAdV-A31, -B16, -B34, -B35, -D8, -D37, -D48, -D73, -D74, -D75, and -D80 as promising candidates for future vector development due to their low binding and neutralizing antibody prevalence.

Analysis of the Prevalence of Binding and Neutralizing Antibodies against 39 Human Adenovirus Types in Student Cohorts Reveals Low-Prevalence Types and a Decline in Binding Antibody Levels during the SARS-CoV-2 Pandemic

Vectors based on human adenoviruses (HAdVs) are important for the development of novel immunizations, oncolytic therapies, and gene therapies. The use of HAdV-based vaccines against Ebola virus, the rapid adaptation of the vector technology for vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and their very good efficacy have shown the great potential of HAdV-based vaccines.

Immunotherapy approaches for malignant pleural mesothelioma

Over the past decade, immune-checkpoint inhibitors (ICIs) have revolutionized the treatment of cancer. In mesothelioma, a rare cancer with a dismal prognosis generally caused by exposure to asbestos, treatment with single or dual ICIs results in robust improvements in overall survival over previous standard-of-care therapies, both in the first-line and relapsed disease settings. Predictive biological features that underpin response to ICIs remain poorly understood; however, insights into the immune microenvironment and genomic landscape of mesothelioma as well as into their association with response or acquired resistance to ICIs are emerging. Several studies of rational combinations involving ICIs with either another ICI or a different agent are ongoing, with emerging evidence of synergistic antitumour activity. Non-ICI-based immunotherapies, such as peptide-based vaccines and mesothelin-targeted chimeric antigen receptor T cells, have demonstrated promising efficacy. Moreover, results from pivotal trials of dendritic cell vaccines and viral cytokine delivery, among others, are eagerly awaited. In this Review, we comprehensively summarize the key steps in the development of immunotherapies for mesothelioma, focusing on strategies that have led to randomized clinical evaluation and emerging predictors of response. We then forecast the future treatment opportunities that could arise from ongoing research.

How Our Continuing Studies of the Pre-clinical Inbred Mouse Models of Mesothelioma Have Influenced the Development of New Therapies

Asbestos-induced preclinical mouse models of mesothelioma produce tumors that are very similar to those that develop in humans and thus represent an ideal platform to study this rare, universally fatal tumor type. Our team and a number of other research groups have established such models as a stepping stone to new treatments, including chemotherapy, immunotherapy and other approaches that have been/are being translated into clinical trials. In some cases this work has led to changes in mesothelioma treatment practice and over the last 30 years these models and studies have led to trials which have improved the response rate in mesothelioma from less than 10% to over 50%. Mouse models have had a vital role in that improvement and will continue to play a key role in the future success of mesothelioma immunotherapy. In this review we focus only on these original inbred mouse models, the large number of preclinical studies conducted using them and their contribution to current and future clinical therapy for mesothelioma.

Immunotherapy for mesothelioma: Moving beyond single immune check point inhibition

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm with low survival rates. Platinum-based chemotherapy has represented the cornerstone of treatment for over a decade, prompting the investigation of new therapeutic strategies both in the early stage of the disease and in the advanced setting. The advent of immune check-point inhibitors (ICIs) has recently revamped the enthusiasm for using immunotherapy also in MPM. However, results from first clinical trials using single immune check-point inhibition have been conflicting, and this may be mainly attributed to the lack of specific biomarkers as well as to intra- and inter- patient heterogeneity. The phase III Checkmate743 firstly demonstrated the superiority of an ICI combination (nivolumab plus ipilimumab) over chemotherapy in the first-line treatment of unresectable MPM, leading to FDA approval of this regimen and showing that moving beyond single immune check point inhibition might be a successful strategy to overcome resistance in the majority of MPM patients. In this review, we describe the emerging immunotherapy strategies for the treatment of MPM. We also discuss how refining the approach in pre-clinical studies towards a more holistic perspective (which takes into account not only genetic but also pathophysiological vulnerabilities) and strengthening multi-institutional collaboration in clinical trials is finally helping the clinical development of immunotherapy in MPM.

The Role of Immunotherapy in the Treatment of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma is a rare and aggressive malignancy arising from mesothelial cells that line the serous membranes of the body. Cytotoxic chemotherapy has been a mainstay of therapy, resulting in a modest improvement in overall survival, but toxicity limits the eligible patient population. Few targeted agents beyond bevacizumab have demonstrated superior efficacy compared to placebos. With an improved understanding of the relationship between the immune system and cancer progression, immunotherapies are playing a greater role in the treatment of many cancers. Several early- and late-phase trials in malignant pleural mesothelioma, including assessments of the first-line efficacy of combination ipilimumab/nivolumab treatment, have now demonstrated promising results for both immune checkpoint inhibition and cell-based therapies. These immune therapies are likely to play a central role in the treatment of this disease going forward.

Biological basis for novel mesothelioma therapies

Mesothelioma is an aggressive cancer that is associated with exposure to asbestos. Although asbestos is banned in several countries, including the UK, an epidemic of mesothelioma is predicted to affect middle-income countries during this century owing to their heavy consumption of asbestos. The prognosis for patients with mesothelioma is poor, reflecting a failure of conventional chemotherapy that has ultimately resulted from an inadequate understanding of its biology. However, recent work has revolutionised the study of mesothelioma, identifying genetic and pathophysiological vulnerabilities, including the loss of tumour suppressors, epigenetic dysregulation and susceptibility to nutrient stress. We discuss how this knowledge, combined with advances in immunotherapy, is enabling the development of novel targeted therapies.

Novel and Promising Systemic Treatment Approaches in Mesothelioma

OPINION STATEMENT

There was limited progress in the development of novel systemic approaches in the treatment of advanced malignant mesothelioma for years following the publication of the pivotal phase III trial of Vogelzang et al. that established the cisplatin/pemetrexed regimen as a standard 1st-line systemic therapy. Since then, over the last several years, a significant step forward has been made, with incorporation of immune checkpoint inhibitors and anti-angiogenic agents. In addition, better appreciation of mesothelioma biology has allowed detection of novelmolecular therapeutic targets. All the above-mentioned strategies, along with the additional promising approaches represented by adoptive T cell therapy, dendritic cell therapy, cancer vaccines, oncoviral therapy, and agents targeting mesothelin are discussed in this review. The clinical research to identify effective biologic targets and treatment combinations in malignant mesothelioma is ongoing.

Emerging avenues in immunotherapy for the management of malignant pleural mesothelioma

BACKGROUND

The role of immunotherapy in cancer is now well-established, and therapeutic options such as checkpoint inhibitors are increasingly being approved in many cancers such as non-small cell lung cancer (NSCLC). Malignant pleural mesothelioma (MPM) is a rare orphan disease associated with prior exposure to asbestos, with a dismal prognosis. Evidence from clinical trials of checkpoint inhibitors in this rare disease, suggest that such therapies may play a role as a treatment option for a proportion of patients with this cancer.

MAIN TEXT

While the majority of studies currently focus on the established checkpoint inhibitors (CTLA4 and PD1/PDL1), there are many other potential checkpoints that could also be targeted. In this review I provide a synopsis of current clinical trials of immunotherapies in MPM, explore potential candidate new avenues that may become future targets for immunotherapy and discuss aspects of immunotherapy that may affect the clinical outcomes of such therapies in this cancer.

CONCLUSIONS

The current situation regarding checkpoint inhibitors in the management of MPM whilst encouraging, despite impressive durable responses, immune checkpoint inhibitors do not provide a long-term benefit to the majority of patients with cancer. Additional studies are therefore required to further delineate and improve our understanding of both checkpoint inhibitors and the immune system in MPM. Moreover, many new potential checkpoints have yet to be studied for their therapeutic potential in MPM. All these plus the existing checkpoint inhibitors will require the development of new biomarkers for patient stratification, response and also for predicting or monitoring the emergence of resistance to these agents in MPM patients. Other potential therapeutic avenues such CAR-T therapy or treatments like oncolytic viruses or agents that target the interferon pathway designed to recruit more immune cells to the tumor also hold great promise in this hard to treat cancer.

Viral vector platforms within the gene therapy landscape

Throughout its 40-year history, the field of gene therapy has been marked by many transitions. It has seen great strides in combating human disease, has given hope to patients and families with limited treatment options, but has also been subject to many setbacks. Treatment of patients with this class of investigational drugs has resulted in severe adverse effects and, even in rare cases, death. At the heart of this dichotomous field are the viral-based vectors, the delivery vehicles that have allowed researchers and clinicians to develop powerful drug platforms, and have radically changed the face of medicine. Within the past 5 years, the gene therapy field has seen a wave of drugs based on viral vectors that have gained regulatory approval that come in a variety of designs and purposes. These modalities range from vector-based cancer therapies, to treating monogenic diseases with life-altering outcomes. At present, the three key vector strategies are based on adenoviruses, adeno-associated viruses, and lentiviruses. They have led the way in preclinical and clinical successes in the past two decades. However, despite these successes, many challenges still limit these approaches from attaining their full potential. To review the viral vector-based gene therapy landscape, we focus on these three highly regarded vector platforms and describe mechanisms of action and their roles in treating human disease.

Gene delivery for immunoengineering

A growing number of gene delivery strategies are being employed for immunoengineering in applications ranging from infectious disease prevention to cancer therapy. Viral vectors tend to have high gene transfer capability but may be hampered by complications related to their intrinsic immunogenicity. Non-viral methods of gene delivery, including polymeric, lipid-based, and inorganic nanoparticles as well as physical delivery techniques, have also been widely investigated. By using either ex vivo engineering of immune cells that are subsequently adoptively transferred or in vivo transfection of cells for in situ genetic programming, researchers have developed different approaches to precisely modulate immune responses. In addition to expressing a gene of interest through intracellular delivery of plasmid DNA and mRNA, researchers are also delivering oligonucleotides to knock down gene expression and immunostimulatory nucleic acids to tune immune activity. Many of these biotechnologies are now in clinical trials and have high potential to impact medicine.

Pleural effusions and pneumothorax: Beyond simple plumbing: Expert opinions on knowledge gaps and essential next steps

Pleural diseases affect millions of people worldwide. Pleural infection, malignant pleural diseases and pneumothorax are common clinical challenges. A large number of recent clinical trials have provided an evidence-based platform to evaluate conventional and novel methods to drain pleural effusions/air which reduce morbidity and unnecessary interventions. These successes have generated significant enthusiasm and raised the profile of pleural medicine as a new subspecialty. The ultimate goal of pleural research is to prevent/stop development of pleural effusions/pneumothorax. Current research studies mainly focus on the technical aspects of pleural drainage. Significant knowledge gaps exist in many aspects such as understanding of the pathobiology of the underlying pleural diseases, pharmacokinetics of pleural drug delivery, etc. Answers to these important questions are needed to move the field forward. This article collates opinions of leading experts in the field in highlighting major knowledge gaps in common pleural diseases to provoke thinking beyond pleural drainage. Recognizing the key barriers will help prioritize future research in the quest to ultimately cure (rather than just drain) these pleural conditions.

Emerging Treatments for Malignant Pleural Mesothelioma: Where Are We Heading?

Malignant pleural mesothelioma (MPM) is an uncommon but aggressive and treatment resistant neoplasm with low survival rates. In the last years we assisted to an exponential growth in the appreciation of mesothelioma pathobiology, leading several new treatments to be investigated both in the early stage of the disease and in the advanced setting. In particular, expectations are now high that immunotherapy will have a leading role in the next years. However, caution is required as results from phase II studies in MPM were often not replicated in larger, randomized, phase III trials. In this review, we describe the most promising emerging therapies for the treatment of MPM, discussing the biological rationale underlying their development as well as the issues surrounding clinical trial design and proper selection of patients for every treatment.

Immunotherapy for mesothelioma: a critical review of current clinical trials and future perspectives

At the clinical level the role of immunotherapy in cancer is currently at a pivotal point. Therapies such as checkpoint inhibitors are being approved at many levels in cancers such as non-small cell lung cancer (NSCLC). Mesothelioma is a rare orphan disease associated with prior exposure to asbestos, with a dismal prognosis. Various clinical trials for checkpoint inhibitors have been conducted in this rare disease, and suggest that such therapies may play a role as a treatment option for a proportion of patients with this cancer. Most recently approved as a salvage therapy in mesothelioma was granted in Japan, regulatory approval for their use in the clinic elsewhere lags. In this article we review the current pertinent clinical trials of immunotherapies in malignant mesothelioma, discuss the current issues that may affect the clinical outcomes of such therapies and further evaluate potential candidate new avenues that may become future targets for immunotherapy in this cancer.

Malignant Pleural Mesothelioma: State-of-the-Art on Current Therapies and Promises for the Future

Malignant pleural mesothelioma (MPM) is a rare, aggressive cancer of the pleural surface associated with asbestos exposure. The median survival of MPM patients is a mere 8-14 months, and there are few biomarkers and no cure available. It is hoped that, eventually, the incidence of MPM will drop and remain low and constant, given that most nations have banned the use of asbestos, but in the meantime, the incidence in Europe is still growing. The exact molecular mechanisms that explain the carcinogenicity of asbestos are not known. Standard therapeutic strategies for MPM include surgery, often coupled with chemotherapy and/or radiotherapy, in a small percentage of eligible patients and chemotherapy in tumors considered unresectable with or without adjuvant radiotherapy. In recent years, several new therapeutic avenues are being explored. These include angiogenesis inhibitors, synthetic lethal treatment, miRNA replacement, oncoviral therapies, and the fast-growing field of immunotherapy alone or in combination with chemotherapy. Of particular promise are the multiple options offered by immunotherapy: immune checkpoint inhibitors, tumor vaccines, and therapies taking advantage of tumor-specific antigens, such as specific therapeutic antibodies or advanced cell-based therapies exemplified by the CAR-T cells. This review comprehensively presents both old and new therapeutic options in MPM, focusing on the results of the numerous recent and on-going clinical trials in the field, including the latest data presented at international meetings (AACR, ASCO, and ESMO) this year, and concludes that more work has to be done in the framework of tailored therapies to identify reliable targets and novel biomarkers to impact MPM management.

Scientific Advances and New Frontiers in Mesothelioma Therapeutics

Malignant pleural mesothelioma (MPM) is a rare and aggressive cancer that arises from the mesothelial surface of the pleural and peritoneal cavities, the pericardium, and rarely, the tunica vaginalis. The incidence of MPM is expected to increase worldwide in the next two decades. However, even with the use of multimodality treatment, MPM remains challenging to treat, with a 5-year survival rate of less than 5%. The International Association for the Study of Lung Cancer has gathered experts in different areas of mesothelioma research and management to summarize the most significant scientific advances and new frontiers related to mesothelioma therapeutics.

Intrapleural immunotherapy: An update on emerging treatment strategies for pleural malignancy

OBJECTIVES

Malignant pleural mesothelioma and malignant pleural effusions are a major therapeutic challenge, and are associated with impairment in quality of life and increased mortality. Advances in systemic therapies of malignant pleural mesothelioma have demonstrated limited clinical benefit and there is ongoing interest in intrapleural immunotherapies which have been demonstrated to be well tolerated overall with variable clinical responses. We have reviewed the literature to provide a comprehensive summary of novel intrapleural immunotherapeutic paradigms, including oncolytic virus therapy, gene-mediated cytotoxic immunotherapy, direct cytokine-mediated immunotherapies, innate immunomodulators and adoptive transfer of intrapleural chimeric antigen receptor T-cell therapy.

DATA SOURCES

A review of PubMed for original manuscripts and conference reports published between 1998 and 2018 pertaining to intrapleural immunotherapy, as well as examination of reference lists from reviewed manuscripts.

STUDY SELECTION

Human clinical trials on intrapleural immunotherapies in subjects with malignant pleural mesothelioma or malignant pleural effusion were included in this review, including some relevant preclinical studies and anticipated ongoing trials reported on Clinicaltrials.gov.

RESULTS

Twenty-six clinical trials were identified, in addition to three trials currently in progress.

CONCLUSION

Intrapleural immunotherapies for pleural malignancy have demonstrated promise with regard to generating durable tumor-specific immune responses with possible clinical benefits which merit further investigation as part of multimodal chemotherapeutic and immunotherapeutic regimens.

Phase I Study of Intrapleural Gene-Mediated Cytotoxic Immunotherapy in Patients with Malignant Pleural Effusion

Gene-mediated cytotoxic immunotherapy (GMCI) is an immune strategy implemented through local delivery of an adenovirus-based vector expressing the thymidine kinase gene (aglatimagene besadenovec, AdV-tk) followed by anti-herpetic prodrug valacyclovir. A phase I dose escalation trial of GMCI followed by chemotherapy was conducted in patients with malignant pleural effusion (MPE). AdV-tk was administered intrapleurally (IP) in three cohorts at a dose of 1 × 10¹² to 10¹³ vector particles. Primary endpoint was safety; secondary endpoints included response rate, progression-free survival, and overall survival. Nineteen patients were enrolled: median age 67 years; 14 with malignant mesothelioma, 4 non-small-cell lung cancer (NSCLC), and 1 breast cancer. There were no dose limiting toxicities. All 3 patients in cohort 2 experienced transient cytokine release syndrome (CRS). Addition of celecoxib in cohort 3 reduced the incidence and severity of CRS (none > grade 2). Three patients are alive (23-33 months after GMCI), and 3 of 4 NSCLC patients had prolonged disease stabilization; one is alive 29 months after GMCI, 3.6 years after initial diagnosis. GMCI was safe and well tolerated in combination with chemotherapy in patients with MPE and showed encouraging response. Further studies are warranted to determine efficacy.

The role of intracavitary therapies in the treatment of malignant pleural mesothelioma

Surgery is one of the steps of multimodality approach for the treatment of MPM. Due to anatomical features, microscopically radical (R0) resection is never possible and a Macroscopic Complete Resection (R1) is considered the target for mesothelioma surgeons. Recently, intracavitary therapies have been described with the aim of extending the loco-regional effect of surgery. Different agents might be administered intrapleurally: chemotherapy drugs are the most widely used, but also photodynamic therapy (PDT) showed to lead to satisfactory long-term outcomes; furthermore, immunotherapies and gene therapies have been also reported. Despite promising results, no high-quality evidences are currently available and controlled randomized trials are required to establish the exact role of intracavitary therapies and to standardize the technique.

T-Cell Therapy Enabling Adenoviruses Coding for IL2 and TNFα Induce Systemic Immunomodulation in Mice With Spontaneous Melanoma

The immunosuppressive microenvironment of solid tumors renders adoptively transferred T cells hypofunctional. However, adenoviral delivery of immunostimulatory cytokines IL2 and TNFα can significantly improve the efficacy of adoptive T-cell therapy. Using ret transgenic mice that spontaneously develop skin malignant melanoma, we analyzed the mechanism of action of adenoviruses coding for IL2 and TNFα in combination with adoptive transfer of TCR-transgenic TRP-2-specific T cells. Following T-cell therapy and intratumoral virus injection, a significant increase in antigen-experienced, tumor-reactive PD-1 CD8 T cells was seen in both cutaneous lesions and in metastatic lymph nodes. A reverse correlation between tumor weight and the number of tumor-reactive PD-1 tumor-infiltrating lymphocytes (TILs) was observed, suggesting that these T cells could target and kill tumor cells. It is interesting to note that, local expression of cytokines did not affect intratumoral levels of T-regulatory cells (Tregs), which had previously been associated with systemic IL2 therapy. Instead, Ad5-IL2 induced upregulation of IL2 receptor α-chain (CD25) on conventional CD4CD25Foxp3 cells, indicating that these CD4 T cells may contribute to CD8 T-cell activation and/or homing. Signs of therapy-induced resistance were also observed as the expression of PD-L1 on tumor-infiltrating granulocytic myeloid-derived suppressor cells was upregulated as a reaction to PD-1+ TILs. Finally, beneficial ratios between tumor-reactive PD-1 CD8 TILs and immunosuppressive cell subsets (Tregs and nitric oxide-producing myeloid-derived suppressor cells) were observed in primary and secondary tumor sites, indicating that local delivery of IL2 and TNFα coding adenoviruses can systemically modify the cellular composition of the tumor microenvironment in favor of adoptively transferred T cells.

Intracavitary Therapeutics for Pleural Malignancies

Pleural malignancies remain a serious therapeutic challenge, and are frequently refractory to standard treatment; however, they have the advantage of occurring in an enclosed cavity readily accessible for examination, biopsy, and serial sampling. Novel therapeutics can be administered via intracavitary delivery to maximize efficacy by targeting the site of involvement and potentially mitigating the adverse effects of systemic therapies. The easy accessibility of the pleural space lends itself well to repeated sampling and analysis to determine efficacy and toxicity of a given treatment paradigm. These factors support the rationale for delivery of novel therapeutics directly into the pleural space.

Progress and challenges in Mesothelioma: From bench to bedside

Malignant Pleural Mesothelioma (MPM) is currently an incurable cancer with a typical survival of 1 year from the time of diagnosis. The recent genomic and transcriptomic characterization of MPM presents new opportunities and challenges for MPM researchers. Recent advances in clinical and laboratory diagnostics, and proposals for an updated, data-driven, staging system, also present new challenges for clinicians and hospital services involved in MPM care. The aim of this review is first to introduce the reader to the topic of MPM, a disease that is causally linked to prior, typically occupational, exposure to asbestos fibres. Secondly, we will discuss MPM from the clinical and laboratory perspectives, including reviews of current and evolving therapies and our present understanding of the molecular basis of the disease. Finally, we will attempt to identify critical knowledge gaps that currently prevent more effective treatment, including the challenges involved in early detection and chemoprophylaxis.

Oncolytic Viral Therapy for Mesothelioma

The limited effectiveness of conventional therapy for malignant pleural mesothelioma demands innovative approaches to this difficult disease. Even with aggressive multimodality treatment of surgery, radiation, and/or chemotherapy, the median survival is only 1–2 years depending on stage and histology. Oncolytic viral therapy has emerged in the last several decades as a rapidly advancing field of immunotherapy studied in a wide spectrum of malignancies. Mesothelioma makes an ideal candidate for studying oncolysis given the frequently localized pattern of growth and pleural location providing access to direct intratumoral injection of virus. Therefore, despite being a relatively uncommon disease, the multitude of viral studies for mesothelioma can provide insight for applying such therapy to other malignancies. This article will begin with a review of the general principles of oncolytic therapy focusing on antitumor efficacy, tumor selectivity, and immune system activation. The second half of this review will detail results of preclinical models and human studies for oncolytic virotherapy in mesothelioma.

Novel insights into mesothelioma biology and implications for therapy

Malignant mesothelioma is a universally lethal cancer that is increasing in incidence worldwide. There is a dearth of effective therapies, with only one treatment (pemetrexed and cisplatin combination chemotherapy) approved in the past 13 years. However, the past 5 years have witnessed an exponential growth in our understanding of mesothelioma pathobiology, which is set to revolutionize therapeutic strategies. From a genomic standpoint, mesothelioma is characterized by a preponderance of tumour suppressor alterations, for which novel therapies are currently in development. Other promising antitumour agents include inhibitors against angiogenesis, mesothelin and immune checkpoints, which are at various phases of clinical trial testing.

Targeting eukaryotic protein translation in mesothelioma

The default mechanism for protein translation in eukaryotes involves activation of the eIF4 complex at the 5' end of mRNA. This activity is upregulated in cancers, resulting in the expression of a variety of proteins necessary for the development and maintenance of the neoplastic state. Not surprisingly, mesothelioma demonstrates this same reliance on activation of 5' cap mediated translation. Efforts are ongoing to target and exploit our knowledge of this key molecular switch for cancer therapy. Agents targeting the critical eIF4E cap binding protein, disruption of the eIF4 complex, and exploitation for oncolytic virotherapy are some of the important areas of current research in mesothelioma protein translational research.

Intrapleural Adenoviral-mediated Endothelial Cell Protein C Receptor Gene Transfer Suppresses the Progression of Malignant Pleural Mesothelioma in a Mouse Model

Malignant pleural mesothelioma (MPM) is an aggressive thoracic cancer with a high mortality rate as it responds poorly to standard therapeutic interventions. Our recent studies showed that expression of endothelial cell protein C receptor (EPCR) in MPM cells suppresses tumorigenicity. The present study was aimed to investigate the mechanism by which EPCR suppresses MPM tumor growth and evaluate whether EPCR gene therapy could suppress the progression of MPM in a mouse model of MPM. Measurement of cytokines from the pleural lavage showed that mice implanted with MPM cells expressing EPCR had elevated levels of IFNγ and TNFα compared to mice implanted with MPM cells lacking EPCR. In vitro studies demonstrated that EPCR expression renders MPM cells highly susceptible to IFNγ + TNFα-induced apoptosis. Intrapleural injection of Ad.EPCR into mice with an established MPM originating from MPM cells lacking EPCR reduced the progression of tumor growth. Ad.EPCR treatment elicited recruitment of macrophages and NK cells into the tumor microenvironment and increased IFNγ and TNFα levels in the pleural space. Ad.EPCR treatment resulted in a marked increase in tumor cell apoptosis. In summary, our data show that EPCR expression in MPM cells promotes tumor cell apoptosis, and intrapleural EPCR gene therapy suppresses MPM progression.

The History of the Bellevue Hospital Chest Service (1903-2015)

For more than 100 years, the Bellevue Hospital Chest Service in New York City has contributed major advances in our understanding of pulmonary disease. Research from the cardiopulmonary laboratory of the Chest Service by Drs. Cournand and Richards resulted in the shared Nobel Prize in Physiology or Medicine in 1956 for the development of human cardiac catheterization. In more recent years, continuing its mission to serve the underserved and respond to health crises, the Bellevue Chest Service has served as a leader in the management of HIV infections, multiple drug-resistant tuberculosis epidemics, early detection of lung cancer, and management of urban asthma. Members of the Chest Service founded the World Trade Center Environmental Health Center shortly after collapse of the towers in 2001. The Chest Service became New York's infectious isolation unit caring for the first patient in New York infected with Ebola virus. Recent research has focused on disease management, with the first in-house Directly Observed Therapy Clinic for treatment of tuberculosis, clinical trials of aerosolized IFN-γ, and translational research on host defense against tuberculosis infection. Studies of the airway mucosa have revealed mechanisms by which ambient pollutants promote asthma. Studies on the World Trade Center firefighters and community populations have promoted understanding of systemic inflammation and small airways function. Today, the partnership between a public hospital and an academic institution promotes the synergy that leads to cost-effective and state-of-the art care for an underserved population as well as cutting-edge training and research.

Pilot and Feasibility Trial Evaluating Immuno-Gene Therapy of Malignant Mesothelioma Using Intrapleural Delivery of Adenovirus-IFNα Combined with Chemotherapy

PURPOSE

"In situ vaccination" using immunogene therapy has the ability to induce polyclonal antitumor responses directed by the patient's immune system.

EXPERIMENTAL DESIGN

Patients with unresectable malignant pleural mesothelioma (MPM) received two intrapleural doses of a replication-defective adenoviral vector containing the human IFNα2b gene (Ad.IFN) concomitant with a 14-day course of celecoxib followed by chemotherapy. Primary outcomes were safety, toxicity, and objective response rate; secondary outcomes included progression-free and overall survival. Biocorrelates on blood and tumor were measured.

RESULTS

Forty subjects were treated: 18 received first-line pemetrexed-based chemotherapy, 22 received second-line chemotherapy with pemetrexed (n = 7) or gemcitabine (n = 15). Treatment was generally well tolerated. The overall response rate was 25%, and the disease control rate was 88%. Median overall survival (MOS) for all patients with epithelial histology was 21 months versus 7 months for patients with nonepithelial histology. MOS in the first-line cohort was 12.5 months, whereas MOS for the second-line cohort was 21.5 months, with 32% of patients alive at 2 years. No biologic parameters were found to correlate with response, including numbers of activated blood T cells or NK cells, regulatory T cells in blood, peak levels of IFNα in blood or pleural fluid, induction of antitumor antibodies, nor an immune-gene signature in pretreatment biopsies.

CONCLUSIONS

The combination of intrapleural Ad.IFN, celecoxib, and chemotherapy proved safe in patients with MPM. OS rate was significantly higher than historical controls in the second-line group. Results of this study support proceeding with a multicenter randomized clinical trial of chemo-immunogene therapy versus standard chemotherapy alone. Clin Cancer Res; 22(15); 3791-800. ©2016 AACR.

Novel insights into the pathophysiology and treatment of malignant pleural mesothelioma

Malignant pleural mesothelioma is an aggressive, treatment-resistant tumor, which continues to increase in frequency throughout the world because the causative agent, asbestos, has high economic importance, particularly in developing countries. Patients typically present with breathlessness and chest pain with pleural effusions. Median survival is around 12 months from diagnosis. Palliative chemotherapy is beneficial for mesothelioma patients with high performance status. The role of aggressive surgery remains controversial. This review will outline some of the recent advances in the development of novel therapies for malignant pleural mesothelioma, with a focus on immunological approaches.

Oncolytic virotherapy for human malignant mesothelioma: recent advances

Cancer virotherapy is an attractive alternative to conventional treatments because it offers a wide range of antitumor effects due to 1) the diversity of the oncolytic viruses that are now available and 2) their multifaceted activities against both tumor cells and tumor vessels, in addition to their ability to induce antitumor immune responses. In this review, we summarize preclinical and clinical data regarding the targeting of malignant mesothelioma (MM) by oncolytic viruses. We also discuss the potential of other oncolytic viruses that have already shown antitumor effects against several malignancies in advanced clinical trials but are yet to be tested against MM cells. Finally, we review how the activation of the immune system and combinations with other types of anticancer treatments could support the development of oncolytic virotherapy for the treatment of MM.

A clinical protocol to inhibit the HGF/c-Met pathway for malignant mesothelioma with an intrapleural injection of adenoviruses expressing the NK4 gene

Background

The hepatocyte growth factor (HGF)/c-Met signal pathway is up-regulated in human mesothelioma and suppression of the HGF/c-Met signaling with a competitive inhibitor, NK4 homologous to HGF in the structure, produced anti-tumor effects to mesothelioma in a preclinical study. Mesothelioma is highly resistant to a number of chemotherapeutic agents but distant metastasis to extra-thoracic organs is relatively infrequent until the late stage.

Methods/design

We planned to conduct a clinical study of gene therapy with adenoviruses expressing the NK4 gene (Ad-NK4) to control the local tumor growth. The study is designed to inject Ad-NK4 into the intrapleural cavity with a dose escalation manner from 10¹⁰ to 10¹² virus particles per patient and to examine safety and possible clinical benefits. The clinical investigation is a first-in-human trial to use the NK4 gene and to block the HGF/c-Met pathway with gene medicine. We conducted in vivo animal experiments to examine the safety level as one of the preclinical studies, and showed that Ad DNA administered in the pleural cavity was detected in many parenchymal organs. Biochemical and pathological analyses showed that liver damages were the major adverse effects with little toxicity to other organs. These studies firstly demonstrated biodistribution and transgene expression after an intrapleural injection of Ad vectors in an animal study, which contrasts with an intravenous injection showing relatively rapid clearance of Ad-NK4.

Discussion

The clinical study can also provide information regarding production of NK4 protein and antibody against NK4, and inhibition levels of the HGF/c-Met pathway by detecting dephosphorylation of c-Met in mesothelioma cells. These data will be crucial to judge whether local production of NK4 molecules can be an anti-cancer strategy.

Trial registration: UMIN clinical trials registry, Japan. Register ID: UMIN15771

Local and systemic therapies for malignant pleural mesothelioma

OPINION STATEMENT

Malignant pleural mesothelioma (MPM) is a challenging disease to treat with median overall survival times ranging between 9-17 months for all stages of disease. Recent clinical trials have improved our understanding of the biology of MPM. However, survival results are still not ideal. For early-stage MPM, patients should be evaluated for trimodality therapy in an experienced cancer center. If treating off-protocol, MPM patients should receive a surgical staging evaluation. The decision to proceed with surgical resection also should be considered after an extensive and thorough pulmonary and cardiac evaluation. If deemed a good surgical candidate, patients should receive surgical resection (pleurectomy/decortication or extrapleural pneumonectomy), adjuvant radiation therapy (hemithoracic external beam or intensity modulated radiation therapy), and either neoadjuvant or adjuvant chemotherapy (cisplatin-pemetrexed for 4 cycles). The optimal precise sequence of the trimodality is unclear and should be decided upon by a multidisciplinary consensus for each individual patient. In general, clinical trial participation should be encouraged. Several trials are currently underway to examine intraoperative therapies, vaccines, immunotherapy additions, and novel radiation therapy techniques. Advances in the field of MPM are reliant on participation in clinical trials and identifying biomarkers that are predictive for response to systemic therapies and prognostic for survival benefit.

New and emerging therapeutic options for malignant pleural mesothelioma: review of early clinical trials

Malignant pleural mesothelioma (MPM) is a rare tumor that is challenging to control. Despite some benefit from using the multimodality-approach (surgery, combination chemotherapy and radiation), survival remains poor. However, current research produced a list of potential therapies. Here, we summarize significant new preclinical and early clinical developments in treatment of MPM, which include mesothelin specific antibody and toxin therapies, interleukin-4 (IL-4) receptor toxins, dendritic cell vaccines, immune checkpoint inhibitors, and gene-based therapies. In addition, several local modalities such as photodynamic therapy, postoperative lavage using betadine, and cryotherapy for local recurrence, have also shown to be effective for local control of disease.

Strict requirement for vector-induced type I interferon in efficacious antitumor responses to virally encoded IL12

Host responses are increasingly considered important for the efficacious response to experimental cancer therapies that employ viral vectors, but little is known about the specific nature of host responses required. In this study, we investigated the role of host type I interferons (IFN-I) in the efficacy of virally delivered therapeutic genes. Specifically, we used a Semliki Forest virus encoding IL12 (SFV-IL12) based on its promise as an RNA viral vector for cancer treatment. Intratumoral injection of SFV-IL12 induced production of IFN-I as detected in serum. IFN-I production was abolished in mice deficient for the IFNβ transcriptional regulator IPS-1 and partially attenuated in mice deficient for the IFNβ signaling protein TRIF. Use of bone marrow chimeric hosts established that both hematopoietic and stromal cells were involved in IFN-I production. Macrophages, plasmacytoid, and conventional dendritic cells were each implicated based on cell depletion experiments. Further, mice deficient in the IFN-I receptor (IFNAR) abolished the therapeutic activity of SFV-IL12, as did a specific antibody-mediated blockade of IFNAR signaling. Reduced efficacy was not caused by an impairment in IL12 expression, because IFNAR-deficient mice expressed the viral IL12 transgene even more strongly than wild-type (WT) hosts. Chimeric host analysis for the IFNAR involvement established a strict requirement in hematopoietic cells. Notably, although tumor-specific CD8 T lymphocytes expanded robustly after intratumoral injection of WT mice with SFV-IL12, this did not occur in mice where IFNAR was inactivated genetically or pharmacologically. Overall, our results argued that the antitumor efficacy of a virally based transgene therapeutic relied strongly on a vector-induced IFN-I response, revealing an unexpected mechanism of action that is relevant to a broad array of current translational products in cancer research.

Harnessing Mechanistic Knowledge on Beneficial Versus Deleterious IFN-I Effects to Design Innovative Immunotherapies Targeting Cytokine Activity to Specific Cell Types

Type I interferons (IFN-I) were identified over 50 years ago as cytokines critical for host defense against viral infections. IFN-I promote anti-viral defense through two main mechanisms. First, IFN-I directly reinforce or induce de novo in potentially all cells the expression of effector molecules of intrinsic anti-viral immunity. Second, IFN-I orchestrate innate and adaptive anti-viral immunity. However, IFN-I responses can be deleterious for the host in a number of circumstances, including secondary bacterial or fungal infections, several autoimmune diseases, and, paradoxically, certain chronic viral infections. We will review the proposed nature of protective versus deleterious IFN-I responses in selected diseases. Emphasis will be put on the potentially deleterious functions of IFN-I in human immunodeficiency virus type 1 (HIV-1) infection, and on the respective roles of IFN-I and IFN-III in promoting resolution of hepatitis C virus (HCV) infection. We will then discuss how the balance between beneficial versus deleterious IFN-I responses is modulated by several key parameters including (i) the subtypes and dose of IFN-I produced, (ii) the cell types affected by IFN-I, and (iii) the source and timing of IFN-I production. Finally, we will speculate how integration of this knowledge combined with advanced biochemical manipulation of the activity of the cytokines should allow designing innovative immunotherapeutic treatments in patients. Specifically, we will discuss how induction or blockade of specific IFN-I responses in targeted cell types could promote the beneficial functions of IFN-I and/or dampen their deleterious effects, in a manner adapted to each disease.

Photodynamic therapy for lung cancer and malignant pleural mesothelioma

Photodynamic therapy (PDT) is a form of non-ionizing radiation therapy that uses a drug, called a photosensitizer, combined with light to produce singlet oxygen ((1)O2) that can exert anti-cancer activity through apoptotic, necrotic, or autophagic tumor cell death. PDT is increasingly being used to treat thoracic malignancies. For early-stage non-small cell lung cancer (NSCLC), PDT is primarily employed as an endobronchial therapy to definitively treat endobronchial or roentgenographically occult tumors. Similarly, patients with multiple primary lung cancers may be definitively treated with PDT. For advanced or metastatic NSCLC and small cell lung cancer (SCLC), PDT is primarily employed to palliate symptoms from obstructing endobronchial lesions causing airway compromise or hemoptysis. PDT can be used in advanced NSCLC to attempt to increase operability or to reduce the extent of operation intervention required, and selectively to treat pleural dissemination intraoperatively following macroscopically complete surgical resection. Intraoperative PDT can be safely combined with macroscopically complete surgical resection and other treatment modalities for malignant pleural mesothelioma (MPM) to improve local control and prolong survival. This report reviews the mechanism of and rationale for using PDT to treat thoracic malignancies, details prospective and major retrospectives studies of PDT to treat NSCLC, SCLC, and MPM, and describes improvements in and future roles and directions of PDT.

Current issues in malignant pleural mesothelioma evaluation and management

Malignant pleural mesothelioma (MPM) is an uncommon disease most often associated with occupational asbestos exposure and is steadily increasing in worldwide incidence. Patients typically present at an older age, with advanced clinical stage and other medical comorbidities, making management quite challenging. Despite great efforts, the prognosis of MPM remains poor, especially at progression after initial treatment. Macroscopic complete resection of MPM can be achieved through extrapleural pneumonectomy (EPP) or extended (ie, radical) pleurectomy (e-P/D) in selected patients and can result in prolonged survival when incorporated into a multimodality approach. Given the morbidity associated with surgical resection of MPM, optimizing identification of appropriate patients is essential. Unfortunately, most patients are not candidates for EPP or e-P/D due to advanced stage, age, and/or medical comorbidity. Pemetrexed and platinum combination chemotherapy has become the cornerstone of therapy for patients with unresectable disease because the combination is associated with improved survival and quality of life in treated patients. However, MPM eventually becomes resistant to initial therapy, and benefit to further lines of therapy has not been substantiated in randomized clinical trials. Translational research has provided exciting insights into tumorigenesis, biomarkers, and immune response in MPM, leading to the development of multiple novel therapeutic agents that are currently in clinical trials. These advances hold the promise of a new era in the treatment of MPM and suggest that this disease will not be left behind in the war on cancer.

Novel induction therapies for pleural mesothelioma

Malignant mesothelioma is becoming increasingly common, and rates of diagnosis are expected to continue to increase in the coming years because of the extensive use of asbestos in industrialized countries and the long time interval between exposure and onset of disease. Although much research has been done on the optimal treatment for this disease, the overall prognosis remains grim. The main components of therapy are surgery, chemotherapy, and radiation therapy, but there is controversy in the literature about the optimal inclusion and sequencing of these treatments, as each has unique risk profiles. We have developed a new Surgery for Mesothelioma After Radiation Therapy protocol consisting of induction-accelerated hemithoracic radiation followed by extrapleural pneumonectomy. The rationale behind this protocol is to maximize both the tumoricidal and immunogenic potential of the radiotherapy while minimizing the radiation toxicity to the ipsilateral lung. Our initial trial demonstrated the feasibility of this approach and has shown encouraging results in patients with epithelial histology. In this article, we reviewed the current literature on induction chemotherapy for mesothelioma as well as described the Surgery for Mesothelioma After Radiation Therapy protocol and upcoming studies of novel induction therapies for mesothelioma.

Interventional therapies for malignant pleural effusions: the present and the future

The approach to management of malignant pleural effusions (MPE) has changed over the past few decades. The key goals of MPE management are to relieve patient symptoms using the least invasive means and in the most cost-effective manner. There is now a realization that patient-reported outcome measures should be the primary goal of MPE treatment, and this now is the focus in most clinical trials. Efforts to minimize patient morbidity are complemented by development of less invasive treatments that have mostly replaced the more aggressive surgical approaches of the past. Therapeutic thoracentesis is simple, effective and generally safe, although its benefits may only be temporary. Pleurodesis is the conventional and for a long time the only definitive therapy available. However, the efficacy and safety of talc pleurodesis has been challenged. Indwelling pleural catheter (IPC) drainage is increasingly accepted worldwide and represents a new concept to improve symptoms without necessarily generating pleural symphysis. Recent studies support the effectiveness of IPC treatment and provide reassurance regarding its safety. An unprecedented number of clinical trials are now underway to improve various aspects of MPE care. However, choosing an optimal intervention for MPE in an individual patient remains a challenge due to our limited understanding of the underlying pathophysiology of breathlessness in MPE and a lack of predictors of survival and pleurodesis outcome. This review provides an overview of common pleural interventional procedures used for MPE management, controversies and limitations of current practice, and areas of research most needed to improve practice in future.