Intraoperative adjuncts for malignant pleural mesothelioma

Optimal surgery for resectable malignant pleural mesothelioma in the setting of multimodality treatment

The surgical treatment of malignant pleural mesothelioma (MPM) involves procedures to achieve macroscopic complete resection, depending on the patient's condition. We reviewed the evolution of surgical approaches for resectable MPM. Since surgery is no more than a single step in the set of processes in multimodality treatment (MMT), we concluded that these procedures should give precedence to lung preservation and minimize resection whenever possible. Postoperative quality of life must be prioritized when the patient can receive appropriate adjuvant therapy.

Feasibility and safety of extended pleurectomy/decortication for malignant pleural mesothelioma. A single group experience

Surgery is part of a multimodal therapeutic approach to malignant pleural mesothelioma (MPM) although its real beneficial effect is still controversial. The optimal precise sequence of treatments within the trimodality is unclear, and should be decided upon a multidisciplinary consensus for each individual patient. Here, we analyzed the perioperative data of 19 MPM patients who underwent extended pleurectomy/decortication (EPD) with curative intent. The mean age at diagnosis was 67 years; 11 males and eight females. Ten patients were diagnosed with MPM via medical thoracoscopy (MT), and nine via video‐assisted thoracoscopic surgery (VATS). The vast majority of cases harbored epitheliod forms. We compared neoadjuvant chemotherapy (NCT) followed by surgery (11 cases) versus surgery followed by adjuvant chemotherapy (ACT, 8 cases) within a 3‐year period. All patients had extended pleurectomy/decortication and none had an extended pneumonectomy. Analysis of survival curves suggested that the short‐term outcomes are better with upfront EDP followed by ACT if compared to EDP preceded by NCT. Although limited, the data highlighted the safety and feasibility of EPD, with manageable postoperative complications and no major burden for the patients.

Repurposing therapeutics for malignant pleural mesothelioma (MPM) - Updates on clinical translations and future outlook

INTRODUCTION

Malignant pleural mesothelioma (MPM) is a rare malignancy affecting the mesothelial cells in the pleural lining surrounding the lungs. First approved chemotherapy against MPM was a platinum/antifolate (cisplatin/pemetrexed) (2003). Since then, no USFDA approvals have gone through for small molecules as these molecules have not been proven to be therapeutically able in later stages of clinical studies. An alternative to conventional chemotherapy can be utilization of monoclonal antibodies, which are proven to improve patient survival significantly as compared to conventional chemotherapy (Nivolumab + Ipilimumab, 2020).

AREA COVERED

Drug repurposing has been instrumental in drug discovery for rare diseases such as MPM and multiple repositioned small molecule therapies and immunotherapies are currently being tested for its applicability in MPM management. This article summarizes essential breakthroughs along the pre-clinical and clinical developmental stages of small molecules and monoclonal antibodies for MPM management.

EXPERT OPINION

For rare diseases such as malignant pleural mesothelioma, a drug repurposing strategy can be adapted as it eases the financial burden on pharmaceutical companies along with fast-tracking development. With the rise of multiple small molecule repurposed therapies and innovations in localized treatment, MPM therapeutics are bound to be more effective in this decade.

An Update on Emerging Therapeutic Options for Malignant Pleural Mesothelioma

The treatment paradigm for malignant pleural mesothelioma (MPM) has changed little in the last 18 years. Radical intent treatment, consisting of surgical resection, radiotherapy and chemotherapy, has been offered to a highly select few; however, there is little randomised evidence to validate this approach. Prior to 2020 chemotherapy with platinum and an anti-folate was the only intervention with randomised evidence to demonstrate improved overall survival (OS) in MPM. No systemic therapy had been demonstrated to improve OS in the second line setting until 2020. The publication of the Checkmate 743 trial in 2021 demonstrated a survival benefit of combination immunotherapy over standard chemotherapy in newly diagnosed patients with MPM. This finding was shortly followed by the CONFIRM trial which demonstrates a modest but significant survival benefit of second line nivolumab versus placebo in patients having previously received standard chemotherapy. The results of these trials, recent biomarker directed therapy and chemotherapy adjuncts are discussed within this review. The integration of immunotherapy for the few patients in whom radical surgical therapy is intended is currently the subject of clinical trials and offers the prospect of improving outcomes in this rare but devastating disease.

Landmark Trials in the Surgical Management of Mesothelioma

The treatment of mesothelioma has evolved slowly over the last 20 years. While surgery as a standalone treatment has fallen out of favor, the importance of multimodality treatment consisting of combinations of chemotherapy, radiotherapy, and surgery have become more common in operable, fit patients. In this review, we discuss trials in surgery, chemotherapy, and radiation that have shaped contemporary multimodality treatment of this difficult malignancy, and we touch on the new and emerging immunotherapeutic and targeted agents that may change the future treatment of this disease. We also review the multimodality treatment regimens, with particular attention to trimodality therapy and neoadjuvant hemithoracic radiation strategies.

Povidone-iodine results in rapid killing of thymic epithelial tumour cells through cellular fixation†

OBJECTIVES

Hyperthermic pleural lavage with povidone-iodine (PVP-I) is utilized to control micrometastatic disease following cytoreductive surgery for thymic epithelial tumours (TETs). Our objective was to investigate whether PVP-I demonstrates direct cytotoxicity against human TET cells.

METHODS

Human Met-5A (immortalized mesothelial cell), IU-TAB-1 (thymoma) and Ty-82 (thymic carcinoma) cell lines were treated with serial dilutions of PVP-I (0.01-10%) for 5, 30 and 60 min at 37°C and 42°C. MTT assays and flow cytometry were used to evaluate cell death and apoptosis. Membrane permeability was assayed by intracellular staining of cleaved poly-ADP-ribose polymerase. Cellular fixation was evaluated by membrane disruption of dead cells by dimethylsulphoxide and by comparing cleaved poly-ADP-ribose polymerase staining following PVP-I with known fixatives.

RESULTS

MTT assays demonstrated that PVP-I concentrations greater than 0.5% led to rapid cell death in both TET cell lines regardless of temperature. IC50 values following 5 min of exposure to PVP-I were 8.4 mM (0.3%) and 13.3 mM (0.48%) for IU-TAB-1 and Ty-82, respectively and 8.9 mM (0.32%) for MeT-5A. Flow cytometry demonstrated that 5-min exposure of either cell line to 1% PVP-I resulted in profound cell death: 74% and 58% at 5 min and 97% and 95% at 30 min, for IU-TAB-1 and Ty-82 cells, respectively. Resistance of PVP-I-treated cells to dimethylsulphoxide lysis and similar cleaved poly-ADP-ribose polymerase expression following PVP-I and known fixatives revealed cellular fixation as the mechanism of death following PVP-I exposure.

CONCLUSIONS

PVP-I results in rapid death of human TET cells and normal mesothelial cells through a cellular fixation mechanism and may, therefore, favourably impact the control of micrometastatic disease following resection of TETs with pleural dissemination.

A Clinical Trial of TumorGlow to Identify Residual Disease During Pleurectomy and Decortication

BACKGROUND

Macroscopic complete resection can improve survival in a select group of patients with malignant pleural mesothelioma. During resection, differentiating residual tumor from inflammation or scar can be challenging. This trial evaluated near-infrared (NIR) intraoperative imaging using TumorGlow (a novel NIR imaging approach utilizing high-dose indocyanine green and delayed imaging) technology to improve detection of macroscopic residual disease.

METHODS

Twenty subjects were enrolled in an open-label clinical trial of NIR intraoperative imaging with TumorGlow (Indocyanine Green for Solid Tumors [NCT02280954]). Twenty-four hours before pleural biopsy or pleurectomy and decortication (P/D), patients received intravenous indocyanine green. All specimens identified during standard-of-care surgical resection and with NIR imaging underwent histopathologic profiling and correlative microscopic fluorescent tomographic evaluation. For subjects undergoing P/D (n = 13), the hemithorax was evaluated with NIR imaging during P/D to assess for residual disease. When possible, additional fluorescent lesions were resected.

RESULTS

Of 203 resected specimens submitted for evaluation, indocyanine green accumulated within 113 of 113 of resected mesothelioma specimens, with a mean signal-to-background fluorescence ratio of 3.1 (SD, 2.2 to 4.8). The mean signal-to-background fluorescence ratio of benign tissues was 2.2 (SD, 1.4 to 2.4), which was significantly lower than in malignant specimens (p = 0.001). NIR imaging identified occult macroscopic residual disease in 10 of 13 subjects. A median of 5.6 resectable residual deposits per patient (range, 0 to 11 deposits per patient), with a mean size of 0.3 cm (range, 0.1 to 1.5 cm), were identified.

CONCLUSIONS

TumorGlow for malignant pleural mesothelioma is safe and feasible. Excellent sensitivity allows for to reliable detection of macroscopic residual disease during cytoreductive surgical procedures.

Combined hyaluronate-based films loaded with pemetrexed and cisplatin for the treatment of malignant pleural mesothelioma: Preliminary evaluation in an orthotopic tumor recurrence model

Malignant pleural mesothelioma (MPM) is a rare malignancy characterized by a long latency period of 20-50 years after exposure to the main aetiology agent that is asbestos. MPM treatments include surgery, chemotherapy, and radiation therapy, with the combination pemetrexed and cisplatin being the standard chemotherapy approach. Despite this multimodality therapy one of the major issues after surgery is the high rate of local recurrence of the tumor. One possible approach would be the intrapleural application of implants loaded with anticancer drug to be applied during surgery to prevent local tumor recurrence. The implant proposed in the present work is a polymeric film of hyaluronic acid loaded with pemetrexed. The film developed is a hydrophilic, thin and flexible film sufficiently resistant to be applied intrapleurally adhering to the mesothelial surface. The release of pemetrexed from the film was found to be complete within2 h in phosphate buffered saline. In an orthotopic model of mesothelioma recurrence in rats, pemetrexed loaded films showed the same antitumor efficacy of pemetrexed disodium solutions administered intravenously or intrapleurally, while when administered in combination with cisplatin-loaded hyaluronate film, the implants almost completely prevented tumor recurrence. The local administration of drug-loaded polymer implants appears an ideal chemotherapy strategy especially for patients in which surgery is already selected as a viable therapeutic option.

Polymeric films loaded with cisplatin for malignant pleural mesothelioma: a pharmacokinetic study in an ovine model

BACKGROUND

Malignant pleural mesothelioma (MPM) continues to be a distressing tumor due to its aggressive biologic behavior and scanty prognosis. Several therapeutic approaches have been tested both in clinical and preclinical settings, being intrapleural chemotherapy one of the most promising. Some years ago, our interest focused on polymeric films loaded with cisplatin for the adjuvant intrapleural treatment of surgical patients. After in vitro and in vivo studies in a rat recurrence model of MPM, the aim of this study was to evaluate the pharmacokinetics of the polymeric films in a sheep model in view of further studies in a clinical setting.

METHODS

An ovine model was used. Animals were divided into four groups according to pharmacologic treatment: control group (three animals undergoing left pneumonectomy and saline-NaCl solution); intrapleural hyaluronate cisplatin films (HYALCIS) group (six animals undergoing left pneumonectomy and intrapleural application of polymeric films loaded with cisplatin); intrapleural cisplatin solution (six animals undergoing left pneumonectomy and intrapleural application of cisplatin solution); intravenous cisplatin (five animals undergoing left pneumonectomy and intravenous administration of cisplatin solution). The primary objective was the plasmatic and pleural concentration of cisplatin in the treatment groups. The secondary objective was the treatment-related toxicity evaluated by plasmatic analysis performed at prearranged time intervals and histological examinations of tissue samples collected during animal autopsy. Analysis of variance (ANOVA) was used for statistical analysis. Bonferroni correction was applied for comparison between all groups.

RESULTS

Twenty female Sardinian sheep with a mean weight of 45.1 kg were studied. All animals survived the surgical procedures. The whole surgical procedure had a mean duration of 113 minutes. Cisplatin blood levels obtained from polymeric films application were low during the first 24 hours after the application; then, the cisplatin blood level increased gradually and progressively until it reached significantly higher plasmatic concentrations after 120 hours compared to intrapleural cisplatin solution (P=0.004) and intravenous administration (P=0.001), respectively. Considering cisplatin concentration at 168 hours after the application, animals treated with polymeric films had higher plasmatic values than animals treated with intrapleural cisplatin solution and intravenous cisplatin (P=0.001). Despite the high cisplatin plasmatic concentrations, treatment related-toxicity towards kidneys and liver was comparatively lower compared to the intravenous and intrapleural cisplatin administration and closer to the control levels.

CONCLUSIONS

Polymeric films loaded with cisplatin allowed to reach significantly higher intrapleural and plasmatic cisplatin concentrations compared to intrapleural and intravenous cisplatin solution, providing at the same time, a significant reduction of treatment related toxicity.

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.