Phase III randomized trial of surgery with or without intraoperative photodynamic therapy and postoperative immunochemotherapy for malignant pleural mesothelioma

The use of photodynamic therapy in medical practice

Cancer therapy, especially for tumors near sensitive areas, demands precise treatment. This review explores photodynamic therapy (PDT), a method leveraging photosensitizers (PS), specific wavelength light, and oxygen to target cancer effectively. Recent advancements affirm PDT's efficacy, utilizing ROS generation to induce cancer cell death. With a history spanning over decades, PDT's dynamic evolution has expanded its application across dermatology, oncology, and dentistry. This review aims to dissect PDT's principles, from its inception to contemporary medical applications, highlighting its role in modern cancer treatment strategies.

Three-dimensional printing of the human lung pleural cavity model for PDT malignant mesothelioma

OBJECTIVE

The primary aim was to investigate emerging 3D printing and optical acquisition technologies to refine and enhance photodynamic therapy (PDT) dosimetry in the management of malignant pleural mesothelioma (MPM).

MATERIALS AND METHODS

A rigorous digital reconstruction of the pleural lung cavity was conducted utilizing 3D printing and optical scanning methodologies. These reconstructions were systematically assessed against CT-derived data to ascertain their accuracy in representing critical anatomic features and post-resection topographical variations.

RESULTS

The resulting reconstructions excelled in their anatomical precision, proving instrumental translation for precise dosimetry calculations for PDT. Validation against CT data confirmed the utility of these models not only for enhancing therapeutic planning but also as critical tools for educational and calibration purposes.

CONCLUSION

The research outlined a successful protocol for the precise calculation of light distribution within the complex environment of the pleural cavity, marking a substantive advance in the application of PDT for MPM. This work holds significant promise for individualizing patient care, minimizing collateral radiation exposure, and improving the overall efficiency of MPM treatments.

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.

Comparison of video-assisted pleurectomy/decortication surgery plus hyperthermic intrathoracic chemotherapy with VATS talc pleurodesis for the treatment of malignant pleural mesothelioma: A pilot study

Hyperthermic intrathoracic chemotherapy (HITHOC) adjunct to surgery for Malignant Pleural Mesothelioma (MPM) has no definite role. The primary objective of this pilot-trial was to evaluate the feasibility for future large studies. The study design was a prospective randomized three-centric pilot trial. We recruited patients diagnosed with MPM and prospectively assigned them to two groups: Group A: Video Assisted Thoracic Surgery (VATS) talc pleurodesis or Group B: Video-assisted P/D plus HITHOC. From November-2011 to July-2017 24 males and 3 females, with a median age of 68-years were enrolled (recruitment rate 5 patients/year). Preoperative stage was I-II, and 18 had epithelioid type. 14 patients were in the Group A. Operative mortality was 0. Follow-up ranged 6-80 months. The median overall survival time started to diverge at 20 months, being 19 months (95% CI 12-25) in Group A and 28 months (95% CI 0-56) in Group B. Survival rate for the epithelioid type was 15 months (95% CI 0-34) in Group A and 45 months (95% CI 0-107) in the Group B. These findings suggest that video-assisted P/D plus HITHOC may improve survival time in MPM patients undergoing surgical treatment and support the need for a larger multicenter randomized clinical trial.

Microneedle Device Delivering Aggregation-Induced Emission Photosensitizers for Enhanced Metronomic Photodynamic Therapy of Cancer

Metronomic photodynamic therapy (mPDT), which induces cancer cell death by prolonged intermittent continuous irradiation at lower light power, has profoundly promising applications. However, the photobleaching sensitivity of the photosensitizer (PS) and the difficulty of delivery pose barriers to the clinical application of mPDT. Here, we constructed a microneedle-based device (Microneedles@AIE PSs) that combined with aggregation-induced emission (AIE) PSs to achieve enhanced mPDT for cancer. Due to the strong anti-photobleaching property of the AIE PS, it can maintain superior photosensitivity even after long-time light exposure. The delivery of the AIE PS to the tumor through a microneedle device allows for greater uniformity and depth. This Microneedles@AIE PSs-based mPDT (M-mPDT) offers better treatment outcomes and easier access, and combining M-mPDT with surgery or immunotherapy can also significantly improve the effectiveness of these clinical therapies. In conclusion, M-mPDT offers a promising strategy for the clinical application of PDT due to its better efficacy and convenience.

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.

The Rationale for "Laser-Induced Thermal Therapy (LITT) and Intratumoral Cisplatin" Approach for Cancer Treatment

Cisplatin is one of the most widely used anticancer drugs in the treatment of various types of solid human cancers, as well as germ cell tumors, sarcomas, and lymphomas. Strong evidence from research has demonstrated higher efficacy of a combination of cisplatin and derivatives, together with hyperthermia and light, in overcoming drug resistance and improving tumoricidal efficacy. It is well known that the antioncogenic potential of CDDP is markedly enhanced by hyperthermia compared to drug treatment alone. However, more recently, accelerators of high energy particles, such as synchrotrons, have been used to produce powerful and monochromatizable radiation to induce an Auger electron cascade in cis-platinum molecules. This is the concept that makes photoactivation of cis-platinum theoretically possible. Both heat and light increase cisplatin anticancer activity via multiple mechanisms, generating DNA lesions by interacting with purine bases in DNA followed by activation of several signal transduction pathways which finally lead to apoptosis. For the past twenty-seven years, our group has developed infrared photo-thermal activation of cisplatin for cancer treatment from bench to bedside. The future development of photoactivatable prodrugs of platinum-based agents injected intratumorally will increase selectivity, lower toxicity and increase efficacy of this important class of antitumor drugs, particularly when treating tumors accessible to laser-based fiber-optic devices, as in head and neck cancer. In this article, the mechanistic rationale of combined intratumor injections of cisplatin and laser-induced thermal therapy (CDDP-LITT) and the clinical application of such minimally invasive treatment for cancer are reviewed.

Current State of Pleural-Directed Adjuncts Against Malignant Pleural Mesothelioma

Multimodality therapy including surgical resection is the current paradigm in treating malignant pleural mesothelioma (MPM), a thoracic surface cancer without cure. The main limitation of all surgical approaches is the lack of long-term durability because macroscopic complete resection (R1 resection) commonly predisposes to locoregional relapse. Over the years, there have been many studies that describe various intrapleural strategies that aim to extend the effect of surgical resection. The majority of these approaches are intraoperative adjuvants. Broadly, there are three therapeutic classes that employ diverse agents. The most common, widely used group of adjuvants are comprised of direct therapeutics such as intracavitary chemotherapy (± hyperthermia). By comparison, the least commonly employed intrathoracic adjuvant is the class comprised of drug-device combinations like photodynamic therapy (PDT). But the most rapidly evolving (new) class with much potential for improved efficacy are therapeutics delivered by specialized drug vehicles such as a fibrin gel containing cisplatin. This review provides an updated perspective on pleural-directed adjuncts in the management of MPM as well as highlighting the most promising near-term technology breakthroughs.

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.

Updates in Staging and Management of Malignant Pleural Mesothelioma

While without treatment, malignant pleural mesothelioma (MPM) confers poor survival, cancer-directed surgery as part of multimodality treatment is associated with a 15% 5-year survival. Extrapleural pneumonectomy (EPP) and radical or extended pleurectomy/decortication (P/D) are the 2 types of resection performed in this context. Preoperative staging is critical to patient selection for surgery; P/D is recommended over EPP in most cases. Adjuvant therapy with intraoperative platforms, traditional chemotherapy, hemithoracic radiotherapy resection, and new immunotherapy agents are instrumental in achieving durable long-term results. We outline the latest understanding of disease staging and describe the current state of literature and practice.

A Novel Prospective Study Assessing the Combination of Photodynamic Therapy and Proton Radiation Therapy: Safety and Outcomes When Treating Malignant Pleural Mesothelioma

Malignant pleural mesothelioma remains difficult to treat, with high failure rates despite optimal therapy. We present a novel prospective trial combining proton therapy (PT) and photodynamic therapy (PDT) and the largest-ever mesothelioma PT experience (n = 10). PDT photosensitizers included porfimer sodium (2 mg·kg-1 ; 24 h drug-light interval) or 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH) (4 mg·m-2 ;48 h) with wavelengths of 630 nm to 60J·cm-2 and 665 nm to 15-45J·cm-2 , respectively. With a median age of 69 years, patients were predominantly male (90%) with epithelioid histology (100%) and stage III-IV disease (100%). PT was delivered to a median of 55.0 CGE/1.8-2.0 CGE (range 50-75 CGE) adjuvantly (n = 8) or as salvage therapy (n = 2) following extended pleurectomy/decortication (ePD)/PDT. Two-year local control was 90%, with distant and regional failure rates of 50% and 30%, respectively. All patients received chemotherapy, and four received immunotherapy. Surgical complications included atrial fibrillation (n = 3), pneumonia (n = 2), and deep vein thrombosis (n = 2). Median survival from PT completion was 19.5 months (30.3 months from diagnosis), and 1- and 2-year survival rates were 58% and 29%. No patient experienced CTCAEv4 grade ≥2 acute or late toxicity. Our prolonged survival in very advanced-stage patients compares favorably to survival for PT without PDT and photon therapy with PDT, suggesting possible spatial or systemic cooperativity and immune effect.

A Phase I Trial of Surgical Resection and Intraoperative Hyperthermic Cisplatin and Gemcitabine for Pleural Mesothelioma

INTRODUCTION

The primary objective of this single-institution phase I clinical trial was to establish the maximum tolerated dose of gemcitabine added to cisplatin and delivered as heated intraoperative chemotherapy after resection of malignant pleural mesothelioma.

METHODS

The extrapleural pneumonectomy (EPP) and pleurectomy/decortication (P/D) treatment arms were based on investigators' assessment of patient fitness and potential for macroscopic complete resection. Previously established intracavitary dosing of cisplatin (range 175-225 mg/m²) with systemic cytoprotection was used in combination with escalating doses of gemcitabine, following a 3-plus-3 design from 100 mg/m² in 100-mg increments.

RESULTS

From 2007 to 2011, 141 patients were enrolled and 104 completed treatment. The median age of those completing treatment was 65 years (range 43-85 years), and 22 (21%) were female. In the EPP arm (n = 59), 31 patients (53%) had the epithelioid histologic type and the median radiographic tumor volume was 236 cm³ (range 16-4285 cm³). In the P/D arm (n = 41), 29 patients (71%) had the epithelioid histologic type and the median tumor volume was 79 cm³ (range 6-1107 cm³). The operative mortality rate was 2%, and 35 and 22 serious adverse events were encountered among 27 patients (46%) and 16 patients (39%) in the EPP and P/D arms, respectively. Dose-limiting toxicity (grade 3 leukopenia) was observed in two patients who were receiving 1100 mg/m² of gemcitabine, thus establishing the maximum tolerated dose at 1000 mg/m², in combination with 175 mg/m² of cisplatin. The median overall and recurrence-free survival times in treated patients were 20.3 and 10.7 months, respectively.

CONCLUSIONS

Combination cisplatin and gemcitabine heated intraoperative chemotherapy can be administered safely and feasibly in the context of complete surgical resection of malignant pleural mesothelioma by EPP or P/D.

Near infrared photoimmunotherapy with avelumab, an anti-programmed death-ligand 1 (PD-L1) antibody

Near Infrared-Photoimmunotherapy (NIR-PIT) is a highly selective tumor treatment that employs an antibody-photo-absorber conjugate (APC). Programmed cell death protein-1 ligand (PD-L1) is emerging as a molecular target. Here, we describe the efficacy of NIR-PIT, using fully human IgG1 anti-PD-L1 monoclonal antibody (mAb), avelumab, conjugated to the photo-absorber, IR700DX, in a PD-L1 expressing H441 cell line, papillary adenocarcinoma of lung. Avelumab-IR700 showed specific binding and cell-specific killing was observed after exposure of the cells to NIR in vitro. In the in vivo study, avelumab-IR700 showed high tumor accumulation and high tumor-background ratio. Tumor-bearing mice were separated into 4 groups: (1) no treatment; (2) 100 μg of avelumab-IR700 i.v.; (3) NIR light exposure only, NIR light was administered; (4) 100 μg of avelumab-IR700 i.v., NIR light was administered. Tumor growth was significantly inhibited by NIR-PIT treatment compared with the other groups (p < 0.001), and significantly prolonged survival was achieved (p < 0.01 vs other groups). In conclusion, the anti-PD-L1 antibody, avelumab, is suitable as an APC for NIR-PIT. Furthermore, NIR-PIT with avelumab-IR700 is a promising candidate of the treatment of PD-L1-expressing tumors that could be readily translated to humans.

Near infrared photoimmunotherapy with an anti-mesothelin antibody

Near Infrared-Photoimmunotherapy (NIR-PIT) is a new, highly selective tumor treatment that employs an antibody-photon absorber conjugate (APC). When the APC attaches to its target cell and is exposed to NIR light, highly selective cell killing is observed. NIR-PIT has been demonstrated with a limited number of antibodies. Mesothelin is overexpressed in several malignancies and is emerging as a therapeutic target. A recently humanized antibody (hYP218) has been generated against mesothelin that demonstrates high affinity binding. Here, we describe the efficacy of NIR-PIT, using hYP218 as the antibody within the APC to target a mesothelin expressing A431/H9 cell. The hYP218 antibody was conjugated to a photo-absorber, IR700 and incubated with the cells. The hYP218-IR700 showed specific binding to cells and cell-specific killing was observed in vitro. After implanting A431/H9 cells in an athymic nude mouse, tumor-bearing mice were treated with the following regimen of NIR-PIT; 100 μg of hYP218-IR700 i.v., NIR light was administered at 50 J/cm2 on day 1 after injection and 100 J/cm2 of light on day 2 after injection. The hYP218-IR700 showed high tumor accumulation and a high tumor-background ratio (TBR). Tumor growth was significantly inhibited by NIR-PIT treatment compared with the other control groups (p < 0.001), and significantly prolonged survival (p < 0.0001 vs other groups). Thus, the new anti-mesothelin antibody, hYP218, is suitable as an antibody-drug conjugate for NIR-PIT. Furthermore, NIR-PIT with hYP218-IR700 is a promising candidate for the treatment of mesothelin-expressing tumors that could be readily translated to humans.

Treatment of Malignant Pleural Mesothelioma: American Society of Clinical Oncology Clinical Practice Guideline

Purpose To provide evidence-based recommendations to practicing physicians and others on the management of malignant pleural mesothelioma. Methods ASCO convened an Expert Panel of medical oncology, thoracic surgery, radiation oncology, pulmonary, pathology, imaging, and advocacy experts to conduct a literature search, which included systematic reviews, meta-analyses, randomized controlled trials, and prospective and retrospective comparative observational studies published from 1990 through 2017. Outcomes of interest included survival, disease-free or recurrence-free survival, and quality of life. Expert Panel members used available evidence and informal consensus to develop evidence-based guideline recommendations. Results The literature search identified 222 relevant studies to inform the evidence base for this guideline. Recommendations Evidence-based recommendations were developed for diagnosis, staging, chemotherapy, surgical cytoreduction, radiation therapy, and multimodality therapy in patients with malignant pleural mesothelioma. Additional information is available at www.asco.org/thoracic-cancer-guidelines and www.asco.org/guidelineswiki .

Radical multimodality therapy for malignant pleural mesothelioma

BACKGROUND

Malignant pleural mesothelioma is an almost always fatal tumour, for which palliative platinum-based chemotherapy is currently the standard treatment. Multimodal therapeutic strategies incorporating surgery, radiation therapy or photodynamic therapy and chemotherapy have been recommended for selected patients but there is no consensus about their effectiveness.

OBJECTIVES

To assess the benefits and harms of radical multimodal treatment options (including radical surgery ± radical radiotherapy ± photodynamic therapy ± systemic therapy) compared to each other or to palliative treatments, for people with malignant pleural mesothelioma.

SEARCH METHODS

We reviewed data from the Cochrane Lung Cancer group's Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and Embase. We also checked reference lists of primary original studies, review articles and relevant conference proceedings manually for further related articles up to 21 March 2017.

SELECTION CRITERIA

We included parallel-group randomised controlled trials of multimodal therapy for people with malignant pleural mesothelioma (stages I, II or III) that measured at least one of the following endpoints: overall survival, health-related health-related quality of life, adverse events or progression-free survival. We considered studies regardless of language or publication status.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted relevant information on participant characteristics, interventions, study outcomes, and data on the outcomes for this review, as well as information on the design and methodology of the studies. Two review authors assessed the risk of bias in the included trials using pre-defined 'Risk of bias' domains. We assessed the methodological quality using GRADE.

MAIN RESULTS

We conducted this review in accordance with the published Cochrane protocol. Two randomised clinical trials with 104 participants fulfilled our inclusion criteria. Both trials were at high risk of bias (for outcomes other than overall survival), and we rated the evidence as moderate quality for overall survival and low quality for all other outcomes. One trial compared combined extrapleural pneumonectomy (EPP) plus neoadjuvant platinum-based chemotherapy plus postoperative high-dose hemithoracic radiotherapy with combined EPP plus platinum-based chemotherapy. The other trial compared EPP plus postoperative hemithoracic radiotherapy with standard (non-radical) therapy alone following platinum-based chemotherapy (patients in the standard therapy arm received continued oncological management according to local policy, which could include further chemotherapy or palliative radiotherapy).For the first trial, median overall survival calculated from registration was 20.8 months (95% confidence interval (CI) 14.4 to 27.8) in the no-radiotherapy group and 19.3 months (95% CI 11.5 to 21.8) in the radiotherapy group. For the second trial, median overall survival was 14.4 months (95% CI 5.3 to 18.7) for patients allocated to EPP and 19.5 months (95% CI 13.4 to time not yet reached) for patients randomised to standard non-radical therapy. In the second trial, 12 serious adverse events were reported during the study period: ten in the EPP group and two in the non-radical therapy group. Overall health-related quality of life scores were not different between the two arms in either study. We could not perform a meta-analysis of the two included trials due to clinical heterogeneity. We also identified three ongoing trials evaluating the topic of our review.

AUTHORS' CONCLUSIONS

The overall strength of the evidence gathered in this review is low and there is a lack of available evidence to support the use of radical multimodality therapy in routine clinical practice (particularly as one trial suggests greater harm). Given the added cost of multimodality treatment and the possible increase in risk of adverse effects, the lack of evidence of their effectiveness probably means that these interventions should currently be limited to clinical trials alone.

Molecularly Targeted Cancer Combination Therapy with Near-Infrared Photoimmunotherapy and Near-Infrared Photorelease with Duocarmycin-Antibody Conjugate

Near-infrared photoimmunotherapy (NIR-PIT) is a highly selective tumor treatment that uses an antibody-photoabsorber conjugate (APC). However, the effect of NIR-PIT can be enhanced when combined with other therapies. NIR photocaging groups, based on the heptamethine cyanine scaffold, have been developed to release bioactive molecules near targets after exposure to light. Here, we investigated the combination of NIR-PIT using panitumumab-IR700 (pan-IR700) and the NIR-releasing compound, CyEt-panitumumab-duocarmycin (CyEt-Pan-Duo). Both pan-IR700 and CyEt-Pan-Duo showed specific binding to the EGFR-expressing MDAMB468 cell line in vitro In in vivo studies, additional injection of CyEt-Pan-Duo immediately after NIR light exposure resulted in high tumor accumulation and high tumor-background ratio. To evaluate the effects of combination therapy in vivo, tumor-bearing mice were separated into 4 groups: (i) control, (ii NIR-PIT, (iii) NIR-release, (iv) combination of NIR-PIT and NIR-release. Tumor growth was significantly inhibited in all treatment groups compared with the control group (P < 0.05), and significantly prolonged survival was achieved (P < 0.05 vs. control). The greatest therapeutic effect was shown with NIR-PIT and NIR-release combination therapy. In conclusion, combination therapy of NIR-PIT and NIR-release enhanced the therapeutic effects compared with either NIR-PIT or NIR-release therapy alone. Mol Cancer Ther; 17(3); 661-70. ©2017 AACR.

Pleurectomy and decortication

Pleurectomy and decortication (P/D) improve survival and quality of life in selected patients with malignant pleural mesothelioma. The operative procedure was not standardized until recently. The goal of the operation is to perform a macroscopic complete resection of the tumor. This often involves resection of the parietal and visceral pleura and invariably a partial or complete resection and prosthetic reconstruction of ipsilateral hemidiaphragm. We describe our operative planning and technique as well as outcomes of P/D reported in current literature.

Near-Infrared Photoimmunotherapy Targeting Prostate Cancer with Prostate-Specific Membrane Antigen (PSMA) Antibody

Prostate-specific membrane antigen (PSMA) is a membrane protein that is overexpressed manifold in prostate cancer and provides an attractive target for molecular therapy. Near-infrared photoimmunotherapy (NIR-PIT) is a highly selective tumor treatment that employs an antibody-photoabsorber conjugate (APC). Here, we describe the efficacy of NIR-PIT, using a fully human IgG₁ anti-PSMA monoclonal antibody (mAb), conjugated to the photoabsorber, IR700DX, in a PSMA-expressing PC3 prostate cancer cell line. Anti-PSMA-IR700 showed specific binding and cell-specific killing was observed after exposure of the cells to NIR light in vitro In the in vivo study, anti-PSMA-IR700 showed high tumor accumulation and high tumor-background ratio. Tumor-bearing mice were separated into 4 groups: (i) no treatment; (ii) 100 μg of anti-PSMA-IR700 i.v.; (iii) NIR light exposure; (iv) 100 μg of anti-PSMA-IR700 i.v., NIR light exposure was administered. These were performed every week for up to 3 weeks. Tumor growth was significantly inhibited by NIR-PIT treatment compared with the other control groups (P < 0.001), and significantly prolonged survival was achieved (P < 0.0001 vs. other control groups). More than two thirds of tumors were cured with NIR-PIT. In conclusion, the anti-PSMA antibody is suitable as an APC for NIR-PIT. Furthermore, NIR-PIT with the anti-PSMA-IR700 antibody is a promising candidate of the treatment of PSMA-expressing tumors and could be readily translated to humans.Implications: NIR-infrared photoimmunotherapy (NIR-PIT) using a fully human anti-PSMA-IR700 conjugate showed potential therapeutic effects against a PSMA-expressing prostate cancer that is readily translated to humans. Mol Cancer Res; 15(9); 1153-62. ©2017 AACR.

Intraoperative adjuncts for malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rapidly fatal disease. Multimodality surgically based therapies may extend survival in select patients, however, local relapse after resection is common. Novel intraoperative adjunctive therapies including heated intraoperative chemotherapy (HIOC), heated intraoperative povidone-iodine (PVP-I), and photodynamic therapy (PDT) target micrometastatic disease and aim to improve local control. This review details the most recent studies and trials of HIOC, heated intraoperative PVP-I, and PDT, this aims to provide an update on some of the most promising intraoperative adjuncts for patients with MPM.

Overview of treatment related complications in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive malignant neoplasm of the pleura related to asbestos exposure. Despite recent advances in therapy for MPM, the prognosis remains poor, with considerable treatment associated morbidity. Radiological assessment plays a central role in the timely identification and subsequent management of treatment related complications in MPM. This review highlights common and uncommon complications associated with and encountered in the post treatment phase.

Interstitial fluid pressure: A novel biomarker to monitor photo-induced drug uptake in tumor and normal tissues

BACKGROUND

Low-dose photodynamic therapy PDT (photoinduction) can modulate tumor vessels and enhance the uptake of liposomal cisplatin (Lipoplatin®) in pleural malignancies. However, the photo-induction conditions must be tightly controlled as overtreatment shuts down tumor vessels and enhances normal tissue drug uptake.

MATERIAL AND METHODS

In a pleural sarcoma and adenocarcinoma rat model (n = 12/group), we applied photoinduction (0.0625 mg/kg Visudyne®, 10 J/cm² ) followed by intravenous Lipoplatin® (5 mg/kg) administration. Tumor and normal tissue IFP were assessed before and up to 1 hour following photoinduction. Lipoplatin® uptake was determined 60 minutes following photoinduction. We then treated the pleura of tumor-free minipigs with high dose photodynamic therapy (PDT) (0.0625 mg/kg Visudyne®, 30 J/cm² , n = 5) followed by Lipoplatin (5 mg/kg) administration.

RESULTS

In rodents, photoinduction resulted in a significant decrease of IFP (P < 0.05) in both tumor types but not in the surrounding normal lung, equally exposed to light. Also, photoinduction resulted in a significant increase of Lipoplatin® uptake in both tumor types (P < 0.05) but not in normal lung. Tumor IFP variation and Lipoplatin® uptake fitted an inverted parabola. In minipigs, high dose photodynamic treatment resulted in pleural IFP increase of some animals which predicted higher Lipoplatin® uptake levels.

CONCLUSION

Normal and tumor vasculatures react differently to PDT. Continuous IFP monitoring in normal and tumor tissues is a promising biomarker of vessel photoinduction. Moderate drop in tumor with no change in normal tissue IFP are predictive of specific Lipoplatin® uptake by cancer following PDT. Lasers Surg. Med. 49:773-780, 2017. © 2017 Wiley Periodicals, Inc.

Malignant pleural mesothelioma: an update on investigation, diagnosis and treatment

Malignant pleural mesothelioma is an aggressive malignancy of the pleural surface, predominantly caused by prior asbestos exposure. There is a global epidemic of malignant pleural mesothelioma underway, and incidence rates are predicted to peak in the next few years.This article summarises the epidemiology and pathogenesis of malignant pleural mesothelioma, before describing some key factors in the patient experience and outlining common symptoms. Diagnostic approaches are reviewed, including imaging techniques and the role of various biomarkers. Treatment options are summarised, including the importance of palliative care and methods of controlling pleural effusions. The evidence for chemotherapy, radiotherapy and surgery is reviewed, both in the palliative setting and in the context of trimodality treatment. An algorithm for managing malignant pleural effusion in malignant pleural mesothelioma patients is presented. Finally new treatment developments and novel therapeutic approaches are summarised.

Expression of estrogen and progesterone receptors across human malignancies: new therapeutic opportunities

Estrogen and progesterone receptors (ERs and PRs) are known for their prognostic as well as treatment predictive value in breast cancer. Although these receptors are differentially expressed in some other malignancies, and likely participate in the biology of those cancer types, the relevance to outcome and therapy is not well established. The use of ER as a highly effective therapeutic target in oncology was pioneered in breast cancer, and the lessons learned from its success could potentially benefit patients with several other malignancies in which hormone receptors are highly expressed. Indeed, there are several potent drugs available that target hormone receptors. These agents show incontrovertible evidence of benefit in patients with hormone receptor-positive breast cancer. It is conceivable that these drugs may have salutary effects in a variety of cancers other than those originating in the breast, based on the overexpression of hormone receptors in some patients, and the preclinical and clinical reports showing responses to these drugs in diverse cancers, albeit in small series or anecdotally. We therefore undertook a literature review in order to summarize the current data regarding the biologic and clinical implications of expression of estrogen and progesterone receptors in various malignancies and the possibilities for deployment of hormone manipulation beyond breast cancer.

Photodynamic Therapy in Non-Gastrointestinal Thoracic Malignancies

Photodynamic therapy has a role in the management of early and late thoracic malignancies. It can be used to facilitate minimally-invasive treatment of early endobronchial tumours and also to palliate obstructive and bleeding effects of advanced endobronchial tumours. Photodynamic therapy has been used as a means of downsizing tumours to allow for resection, as well as reducing the extent of resection necessary. It has also been used successfully for minimally-invasive management of local recurrences, which is especially valuable for patients who are not eligible for radiation therapy. Photodynamic therapy has also shown promising results in mesothelioma and pleural-based metastatic disease. As new generation photosensitizers are being developed and tested and methodological issues continue to be addressed, the role of photodynamic therapy in thoracic malignancies continues to evolve.

Treatment of pleural malignancies by photo-induction combined to systemic chemotherapy: Proof of concept on rodent lung tumors and feasibility study on porcine chest cavities

BACKGROUND

Low-dose, Visudyne®-mediated photodynamic therapy (photo-induction) was shown to selectively enhance tumor vessel transport causing increased uptake of systemically administered chemotherapy in various tumor types grown on rodent lungs. The present experiments explore the efficacy of photo-induced vessel modulation combined to intravenous (IV) liposomal cisplatin (Lipoplatin®) on rodent lung tumors and the feasibility/toxicity of this approach in porcine chest cavities.

MATERIAL AND METHODS

Three groups of Fischer rats underwent orthotopic sarcoma (n = 14), mesothelioma (n = 14), or adenocarcinoma (n = 12) implantation on the left lung. Half of the animals of each group had photo-induction (0.0625 mg/kg Visudyne®, 10 J/cm(2) ) followed by IV administration of Lipoplatin® (5 mg/kg) and the other half received Lipoplatin® without photo-induction. Then, two groups of minipigs underwent intrapleural thoracoscopic (VATS) photo-induction (0.0625 mg/kg Visudyne®; 30 J/cm(2) hilum; 10 J/cm(2) apex/diaphragm) with in situ light dosimetry in combination with IV Lipoplatin® administration (5 mg/kg). Protocol I (n = 6) received Lipoplatin® immediately after light delivery and Protocol II (n = 9) 90 minutes before light delivery. Three additional animals received Lipoplatin® and VATS pleural biopsies but no photo-induction (controls). Lipoplatin® concentrations were analyzed in blood and tissues before and at regular intervals after photo-induction using inductively coupled plasma mass spectrometry.

RESULTS

Photo-induction selectively increased Lipoplatin® uptake in all orthotopic tumors. It significantly increased the ratio of tumor to lung Lipoplatin® concentration in sarcoma (P = 0.0008) and adenocarcinoma (P = 0.01) but not in mesothelioma, compared to IV drug application alone. In minipigs, intrapleural photo-induction combined to systemic Lipoplatin® was well tolerated with no toxicity at 7 days for both treatment protocols. The pleural Lipoplatin® concentrations were not significantly different at 10 and 30 J/cm(2) locations but they were significantly higher in protocol I compared to II (2.37 ± 0.7 vs. 1.37 ± 0.7 ng/mg, P  < 0.001).

CONCLUSION

Visudyne®-mediated photo-induction selectively enhances the uptake of IV administered Lipoplatin® in rodent lung tumors. Intrapleural VATS photo-induction with identical treatment conditions combined to IV Lipoplatin chemotherapy is feasible and well tolerated in a porcine model. Lasers Surg. Med. 47:807-816, 2015. © 2015 Wiley Periodicals, Inc.

Latest developments in our understanding of the pathogenesis of mesothelioma and the design of targeted therapies

Malignant mesothelioma is an aggressive cancer whose pathogenesis is causally linked to occupational exposure to asbestos. Familial clusters of mesotheliomas have been observed in settings of genetic predisposition. Mesothelioma incidence is anticipated to increase worldwide in the next two decades. Novel treatments are needed, as current treatment modalities may improve the quality of life, but have shown modest effects in improving overall survival. Increasing knowledge on the molecular characteristics of mesothelioma has led to the development of novel potential therapeutic strategies, including: molecular targeted approaches, that is the inhibition of vascular endothelial growth factor with bevacizumab; immunotherapy with chimeric monoclonal antibody, immunotoxin, antibody drug conjugate, vaccine and viruses; inhibition of asbestos-induced inflammation, that is aspirin inhibition of HMGB1 activity may decrease or delay mesothelioma onset and/or growth. We elaborate on the rationale behind new therapeutic strategies, and summarize available preclinical and clinical results, as well as efforts still ongoing.

Dual roles of nitric oxide in the regulation of tumor cell response and resistance to photodynamic therapy

Photodynamic therapy (PDT) against cancer has gained attention due to the successful outcome in some cancers, particularly those on the skin. However, there have been limitations to PDT applications in deep cancers and, occasionally, PDT treatment resulted in tumor recurrence. A better understanding of the underlying molecular mechanisms of PDT-induced cytotoxicity and cytoprotection should facilitate the development of better approaches to inhibit the cytoprotective effects and also augment PDT-mediated cytotoxicity. PDT treatment results in the induction of iNOS/NO in both the tumor and the microenvironment. The role of NO in cytotoxicity and cytoprotection was examined. The findings revealed that NO mediates its effects by interfering with a dysregulated pro-survival/anti-apoptotic NF-κB/Snail/YY1/RKIP loop which is often expressed in cancer cells. The cytoprotective effect of PDT-induced NO was the result of low levels of NO that activates the pro-survival/anti-apoptotic NF-κB, Snail, and YY1 and inhibits the anti-survival/pro-apoptotic and metastasis suppressor RKIP. In contrast, PDT-induced high levels of NO result in the inhibition of NF-kB, Snail, and YY1 and the induction of RKIP, all of which result in significant anti-tumor cytotoxicity. The direct role of PDT-induced NO effects was corroborated by the use of the NO inhibitor, l-NAME, which reversed the PDT-mediated cytotoxic and cytoprotective effects. In addition, the combination of the NO donor, DETANONOate, and PDT potentiated the PDT-mediated cytotoxic effects. These findings revealed a new mechanism of PDT-induced NO effects and suggested the potential therapeutic application of the combination of NO donors/iNOS inducers and PDT in the treatment of various cancers. In addition, the study suggested that the combination of PDT with subtoxic cytotoxic drugs will result in significant synergy since NO has been shown to be a significant chemo-immunosensitizing agent to apoptosis.

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PDT-mediated cytotoxic and cytoprotective effects depend also by the induction of NO from tumor.

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The PDT-induced NO modulates the dysregulated NF-kB/Snail/RKIP loop.

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The direct role of NO induction by PDT was corroborated by the use of the NO inhibitor, l-NAME.

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The combination of an NO donor and PDT resulted in a increased cytotoxic effect, in vitro and in vivo.

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Novel potential therapeutic applications are proposed for the use of PDT combined with NO donors.

Near infrared photoimmunotherapy in the treatment of pleural disseminated NSCLC: preclinical experience

Pleural metastases are common in patients with advanced thoracic cancers and are a cause of considerable morbidity and mortality yet is difficult to treat. Near Infrared Photoimmunotherapy (NIR-PIT) is a cancer treatment that combines the specificity of intravenously injected antibodies for targeting tumors with the toxicity induced by photosensitizers after exposure to NIR-light. Herein, we evaluate the efficacy of NIR-PIT in a mouse model of pleural disseminated non-small cell lung carcinoma (NSCLC). In vitro and in vivo experiments were conducted with a HER2, luciferase and GFP expressing NSCLC cell line (Calu3-luc-GFP). An antibody-photosensitizer conjugate (APC) consisting of trastuzumab and a phthalocyanine dye, IRDye-700DX, was synthesized. In vitro NIR-PIT cytotoxicity was assessed with dead staining, luciferase activity, and GFP fluorescence intensity. In vivo NIR-PIT was performed in mice with tumors implanted intrathoracic cavity or in the flank, and assessed by tumor volume and/or bioluminescence and fluorescence thoracoscopy. In vitro NIR-PIT-induced cytotoxicity was light dose dependent. In vivo NIR-PIT led significant reductions in both tumor volume (p = 0.002 vs. APC) and luciferase activity (p = 0.0004 vs. APC) in a flank model, and prolonged survival (p < 0.0001). Bioluminescence indicated that NIR-PIT lead to significant reduction in pleural dissemination (1 day after PIT; p = 0.0180). Fluorescence thoracoscopy confirmed the NIR-PIT effect on disseminated pleural disease. In conclusion, NIR-PIT has the ability to effectively treat pleural metastases caused by NSCLC in mice. Thus, NIR-PIT is a promising therapy for pleural disseminated tumors.

An IR Navigation System for Pleural PDT

Pleural photodynamic therapy (PDT) has been used as an adjuvant treatment with lung-sparing surgical treatment for malignant pleural mesothelioma (MPM). In the current pleural PDT protocol, a moving fiber-based point source is used to deliver the light. The light fluences at multiple locations are monitored by several isotropic detectors placed in the pleural cavity. To improve the delivery of light fluence uniformity, an infrared (IR) navigation system is used to track the motion of the light source in real-time at a rate of 20 - 60 Hz. A treatment planning system uses the laser source positions obtained from the IR camera to calculate light fluence distribution to monitor the light fluence uniformity on the surface of the pleural cavity. A novel reconstruction algorithm is used to determine the pleural cavity surface contour. A dual-correction method is used to match the calculated fluences at detector locations to the detector readings. Preliminary data from a phantom shows superior light uniformity using this method. Light fluence uniformity from patient treatments is also shown with and without the correction method.

A case of advanced malignant pleural mesothelioma treatment with chemotherapy and photodynamic therapy

Malignant pleural mesothelioma (MPM) is an aggressive, treatment-resistant, and generally fatal disease. A 68-year-old male who was diagnosed with MPM at another hospital came to our hospital with dyspnea. We advised him to take combination chemotherapy but he refused to take the treatment. That was because he had already received chemotherapy with supportive care at another hospital but his condition worsened. Thus, we recommended photodynamic therapy (PDT) to deal with the dyspnea and MPM. After PDT, the dyspnea improved and the patient then decided to take the combination chemotherapy. Our patient received chemotherapy using pemetrexed/cisplatin. Afterwards, he received a single PDT treatment and then later took chemotherapy using gemcitabine/cisplatin. The patient showed a survival time of 27 months, which is longer than median survival time in advanced MPM patients. Further research and clinical trials are needed to demonstrate any synergistic effect between the combination chemotherapy and PDT.

Meta-analysis of survival after pleurectomy decortication versus extrapleural pneumonectomy in mesothelioma

BACKGROUND

This comprehensive meta-analysis was conducted to answer the question as to which procedure, pleurectomy decortication (P/D) or extrapleural pneumonectomy (EPP) is more beneficial to malignant pleural mesothelioma patients' outcome.

METHODS

Original research studies that evaluated long-term outcomes of P/D versus EPP were identified, from January 1990 to January 2014. The combined percent perioperative and 2-year mortality, and median survival were calculated according to both a fixed and a random effect model. The Q statistics and I(2) statistic were used to test for heterogeneity between the studies.

RESULTS

There were 24 distinct data sets, for a total of 1,512 patients treated with P/D, and 1,391 treated with EPP. There was a significantly higher proportion of short-term deaths in the EPP group versus the P/D group (percent mortality meta estimate; 4.5% vs 1.7%; p < 0.05). There was no statistically significant difference in 2-year mortality between the 2 groups, but there was significant heterogeneity.

CONCLUSIONS

The reanalysis of the large number of studies comparing P/D to EPP suggests that P/D is associated with a 2 ½-fold lower short-term mortality (perioperatively and within 30 days) than EPP. Pleurectomy decortication should therefore be preferred when technically feasible.

Combination effect of photodynamic therapy using NPe6 with pemetrexed for human malignant pleural mesothelioma cells

To identify a possible new treatment modality for malignant pleural mesothelioma (MPM), we examined whether combination treatment consisting of pemetrexed chemotherapy and photodynamic therapy (PDT) using the photosensitizer NPe6, enhanced the antitumor effect in both in vitro and in vivo models. We also investigated preclinical treatment schedules. Four human malignant mesothelioma cell lines (MSTO‑211H, H2052, H2452 and H28) were assayed using the WST assay after treatment with pemetrexed and NPe6‑PDT. The treatment schedule for the combination treatment was examined using nude mice. Pemetrexed pre‑treatment enhanced the lethal effect of NPe6‑PDT in the four malignant mesothelioma cell lines, but NPe6‑PDT followed by pemetrexed treatment did not enhance cell lethality in the in vitro assay. Pemetrexed pre‑treatment did not enhance the intracellular accumulation of NPe6, which is one of the determinants of the antitumor effect of PDT. In nude mice injected with MSTO‑211H cells and then treated using a combination of pemetrexed and NPe6‑PDT (10 mg/kg NPe6, 10 J/cm(2) laser irradiation), the tumor volume decreased by 50% but subsequently increased, reaching the pre‑treatment value after 14 days. Pemetrexed treatment followed by NPe6‑PDT resulted in an 80% reduction in the tumor size and inhibited re‑growth. NPe6‑PDT followed by pemetrexed treatment resulted in a 60% reduction in tumor size but did not inhibit re‑growth. NPe6‑PDT induced the expression of thymidylate synthase (TS), which confers resistance to pemetrexed, and NPe6‑PDT followed by pemetrexed treatment did not enhance the treatment outcome in vivo. In conclusion, combination treatment, consisting of pemetrexed followed by NPe6‑PDT, should be further investigated as a new treatment modality for MPM. In the future, this combination treatment may contribute to a reduction in local recurrence and a prolonged survival period in patients with MPM.

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.

Photosensitizers in clinical PDT

Photosensitizers in photodynamic therapy allow for the transfer and translation of light energy into a type II chemical reaction. In clinical practice, photosensitizers arise from three families-porphyrins, chlorophylls, and dyes. All clinically successful photosensitizers have the ability to a greater or lesser degree, to target specific tissues or their vasculature to achieve ablation. Each photosensitizer needs to reliably activate at a high enough light wavelength useful for therapy. Their ability to fluoresce and visualize the lesion is a bonus. Photosensitizers developed from each family have unique properties that have so far been minimally clinically exploited. This review looks at the potential benefits and consequences of each major photosensitizer that has been tried in a clinical setting.

Photodynamic therapy enhanced by hyperbaric oxygenation in palliation of malignant pleural mesothelioma: clinical experience

INTRODUCTION

Surgical debulking followed by radiotherapy/chemotherapy are the standards in the palliative treatment schedule of malignant pleural mesothelioma. The aim of this study was to evaluate the additional effect of intraoperative photodynamic therapy (PDT) under hyperbaric oxygenation (HBO) if compared to decortication alone.

PATIENTS AND METHODS

From January 1993 to August 2003, decortication was done in 34 patients (28 males, 6 females; mean age: 65 years) suffering from advanced malignant pleural mesothelioma. Twenty-two patients received additional intraoperative PDT under HBO. The surgery and PDT/HBO was done 48h after photosensitization with a polyhematoporphyrin, 2mg/kg BW using a diode laser delivering red light at 630nm through a microlens. The light dose was calculated for 300J at a distance of 1cm from the tumour surface.

RESULTS

At 6-month follow-up the Karnofsky performance status showed no significant difference (P≥0.05) between both groups. CT scans documented focal regrowth of the tumour after 6 months in 10/12 cases of the non-PDT group. However, in the PDT group tumour regrowth was detected in only 9/22 cases at 6-month follow-up. Survival analysis showed a significant advantage for the group with PDT (log-rank test: P=0.0179).

CONCLUSION

Although the study includes only a small number of patients, it indicates that additional PDT/HBO represents a safe and technically feasible approach in the palliative setting of advanced malignant mesothelioma of the pleura.

Definitive surgery and intraoperative photodynamic therapy: a prospective study of local control and survival for patients with pleural dissemination of non-small cell lung cancer

Patients with non-small cell lung cancer (NSCLC) with pleural dissemination have very limited survivals often of just 6-9 months. Prior reports of aggressive surgical resection of pleural metastases have shown no consistent improvements in overall survival and very high rates of local recurrences. Based on this and the generally very diffuse pleural dissemination seen in patients, chemotherapy and palliative interventions are standard of care. By attempting to sterile microscopic residual disease after surgical resection, intraoperative photodynamic therapy (PDT) could improve local pleural control and overall survival compared with surgery alone for patients with NSCLC with pleural metastasis. Prior attempts to demonstrate an improvement in clinical outcomes with PDT as an intraoperative adjuvant combined with definitive surgery to treat pleural malignancies have not been successful, perhaps due, in part, to limited ability to perform real-time dosimetry and ensure adequate and even light distribution throughout the chest cavity. A stratified phase II trial assessed the efficacy of definitive surgery and intraoperative PDT with real-time dosimetry in patients with NSCLC with pleural dissemination demonstrated prolonged local control and a higher than expected 21.7-month median survival from the time of surgery and PDT among 22 enrolled patients. This is the first ever report describing optimal methods, techniques, and dosimetry that could be used to safely and reproducibly deliver intraoperative PDT to the chest cavity as part of multimodality therapy for NSCLC with pleural metastasis.

Intraoperative photodynamic therapy for malignant pleural mesothelioma: future or fad?

SUMMARY Malignant pleural mesothelioma is one of the most lethal cancers known to man, typically resulting in a life expectancy of approximately 1 year from the time of diagnosis. Surgery remains investigational in the treatment of this cancer, yet the treatments that appear to have the greatest potential to impact the course of the disease are those that are surgery-based. The goal of surgery, as part of a multimodal treatment plan, is to achieve a macroscopic complete resection of the cancer. There are two surgical approaches, extrapleural pneumonectomy and lung-sparing surgery. Extrapleural pneumonectomy is the most standardized approach and almost certainly achieves the most complete resection, leaving behind the least amount of microscopic disease. Essentially, no aspects of lung-sparing operations are standardized and all techniques are likely to leave behind more microscopic cancer than an extrapleural pneumonectomy, yet this approach has the principal advantage of avoiding pneumonectomy for what is rightfully considered a palliative procedure. There are some recent reports revealing more favorable survivals for patients undergoing lung-sparing rather than lung-sacrificing surgery, but there is no conclusive evidence favoring either approach due to general limitations in the surgical literature for malignant pleural mesothelioma. One multimodal approach that has produced notably long survival rates incorporated radical pleurectomy and adjuvant chemotherapy with intraoperative photodynamic therapy, a light-based cancer treatment. There is speculation that a photodynamic therapy-initiated immune response may have played a role in these results, but this has not been established. The contribution, if any, of photodynamic therapy to these results is an area of active investigation.

New insights into understanding the mechanisms, pathogenesis, and management of malignant mesotheliomas

Malignant mesothelioma (MM) is a relatively rare but devastating tumor that is increasing worldwide. Yet, because of difficulties in early diagnosis and resistance to conventional therapies, MM remains a challenge for pathologists and clinicians to treat. In recent years, much has been revealed regarding the mechanisms of interactions of pathogenic fibers with mesothelial cells, crucial signaling pathways, and genetic and epigenetic events that may occur during the pathogenesis of these unusual, pleiomorphic tumors. These observations support a scenario whereby mesothelial cells undergo a series of chronic injury, inflammation, and proliferation in the long latency period of MM development that may be perpetuated by durable fibers, the tumor microenvironment, and inflammatory stimuli. One culprit in sustained inflammation is the activated inflammasome, a component of macrophages or mesothelial cells that leads to production of chemotactic, growth-promoting, and angiogenic cytokines. This information has been vital to designing novel therapeutic approaches for patients with MM that focus on immunotherapy, targeting growth factor receptors and pathways, overcoming resistance to apoptosis, and modifying epigenetic changes.