Multimodal therapy of epithelioid pleural mesothelioma: improved survival by changing the surgical treatment approach.

Background: The exact role and type of surgery for malignant pleural mesothelioma (MPM) remains controversial. This study aimed at analyzing a 20-year single center perioperative experience in MPM surgery at our high-volume thoracic surgery center and comparing the overall survival after trimodal extrapleural pneumonectomy (EPP) and extended pleurectomy and decortication combined with hyperthermic intrathoracic chemoperfusion (EPD/HITOC) and adjuvant chemotherapy with that after chemotherapy (CTx) alone. Methods: Patients with epithelioid MPM treated with neoadjuvant chemotherapy, EPP and adjuvant radiotherapy within a trimodal concept or EPD/HITOC in combination with adjuvant chemotherapy between 2001 and 2018 were included in this retrospective analysis. Surgical cohorts were compared to patients treated with standard chemotherapy. Results: Overall, 182 patients (69 EPP, 57 EPD/HITOC, 56 CTx) were analyzed. Due to occupational exposure to asbestos for most of the patients, 154 patients (84.6%) were male. The patients in the surgical cohorts were significantly younger than those in the CTx cohort. There was no significant difference between the proportion of patient age and side. The median overall survival of the EPD/HITOC cohort with 38.1 months was significantly longer than that of the EPP and CTx cohorts (24.0 and 15.8 months). Better survival was significantly associated with an ECOG 0 performance status, age below 70 years, and negative lymph node status. In the multivariate analysis, EPD/HITOC was significantly associated with improved overall survival. Perioperative morbidity was lower in the EPD/HITOC group than in the EPP cohort. Conclusions: EPD/HITOC is feasible and safe for localized epithelioid pleural mesothelioma. Changing the surgical approach to a less radical lung-sparing technique may improve overall survival compared to trimodal EPP.

WNT4 overexpression and secretion in thymic epithelial tumors drive an autocrine loop in tumor cells in vitro.

Background: WNT4-driven non-canonical signaling is crucial for homeostasis and age-related involution of the thymus. Abnormal WNT signaling is important in many cancers, but the role of WNT signaling in thymic tumors is largely unknown. Materials & Methods: Expression and function of WNT4 and FZD6 were analyzed using qRT-PCR, Western blot, ELISA, in biopsies of non-neoplastic thymi (NT), thymoma and thymic carcinomas. ShRNA techniques and functional assays were used in primary thymic epithelial cells (pTECs) and TC cell line 1889c. Cells were conventionally (2D) grown and in three-dimensional (3D) spheroids. Results: In biopsy, WHO classified B3 thymomas and TCs showed increased WNT4 expression compared with NTs. During short-term 2D culture, WNT4 expression and secretion declined in neoplastic pTECs but not in 3D spheroids or medium supplemented with recombinant WNT4 cultures. Under the latter condition, the growth of pTECs was accompanied by increased expression of non-canonical targets RAC1 and JNK. Down-regulation of WNT4 by shRNA induced cell death in pTECs derived from B3 thymomas and led to decreased RAC1, but not JNK protein phosphorylation. Pharmacological inhibition of NF-κB decreased both RAC1 and JNK phosphorylation in neoplastic pTECs. Conclusions: Lack of the age-related decline of non-canonical WNT4 expression in TETs and restoration of declining WNT4 expression through exogeneous WNT4 or 3D culture of pTECs hints at an oncogenic role of WNT4 in TETs and is compatible with the WNT4 autocrine loop model. Crosstalk between WNT4 and NF-κB signaling may present a promising target for combined interventions in TETs.

Metabolic Profiling of Thymic Epithelial Tumors Hints to a Strong Warburg Effect, Glutaminolysis and Precarious Redox Homeostasis as Potential Therapeutic Targets.

Thymomas and thymic carcinomas (TC) are malignant thymic epithelial tumors (TETs) with poor outcome, if non-resectable. Metabolic signatures of TETs have not yet been studied and may offer new therapeutic options. Metabolic profiles of snap-frozen thymomas (WHO types A, AB, B1, B2, B3, n = 12) and TCs (n = 3) were determined by high resolution magic angle spinning 1H nuclear magnetic resonance (HRMAS 1H-NMR) spectroscopy. Metabolite-based prediction of active KEGG metabolic pathways was achieved with MetPA. In relation to metabolite-based metabolic pathways, gene expression signatures of TETs (n = 115) were investigated in the public "The Cancer Genome Atlas" (TCGA) dataset using gene set enrichment analysis. Overall, thirty-seven metabolites were quantified in TETs, including acetylcholine that was not previously detected in other non-endocrine cancers. Metabolite-based cluster analysis distinguished clinically indolent (A, AB, B1) and aggressive TETs (B2, B3, TCs). Using MetPA, six KEGG metabolic pathways were predicted to be activated, including proline/arginine, glycolysis and glutathione pathways. The activated pathways as predicted by metabolite-profiling were generally enriched transcriptionally in the independent TCGA dataset. Shared high lactic acid and glutamine levels, together with associated gene expression signatures suggested a strong "Warburg effect", glutaminolysis and redox homeostasis as potential vulnerabilities that need validation in a large, independent cohort of aggressive TETs. If confirmed, targeting metabolic pathways may eventually prove as adjunct therapeutic options in TETs, since the metabolic features identified here are known to confer resistance to cisplatin-based chemotherapy, kinase inhibitors and immune checkpoint blockers, i.e., currently used therapies for non-resectable TETs.

Cytoreductive Thoracic Surgery Combined with Hyperthermic Chemoperfusion for Pleural Malignancies: A Single-Center Experience.

BACKGROUND: Lung-sparing cytoreductive surgery by extended pleurectomy and decortication (EPD) in combination with hyperthermic intrathoracic chemoperfusion (HITOC) forms a promising treatment strategy for malignant pleural mesothelioma and recurrent pleural thymic malignancies. OBJECTIVES: The objective of this study was to scrutinize the surgical procedure and perioperative patient management with emphasis on perioperative morbidity and local tumor control. METHODS: In 2014, a standardized EPD and HITOC procedure was implemented at the Thoraxklinik Heidelberg. This retrospective analysis included clinical data of consecutive patients with pleural mesothelioma and pleural metastasized malignancies treated by EPD and HITOC. The surgical procedure, perioperative management, lung function data, and progression-free survival (PFS) were analyzed. RESULTS: In the time range between April 2, 2014 and July 2018, 76 patients with pleural malignancies have been treated with EPD and HITOC, and were analyzed retrospectively. It included 61 patients with pleural mesothelioma and 15 patients with pleural metastases of thymic malignancies (12), non-small cell lung cancer (1), colorectal carcinoma (1), and sarcoma (1). Perioperative morbidity following EPD and HITOC treatments represented 23.7% of overall malignancies, while 30- and 90-day mortality were 0 and 1.3%, respectively. Median PFS lasted 18.4 months for mesothelioma and 72.2 months for thymic malignancies. CONCLUSION: Combining EPD with HITOC can be performed in patients with either pleural mesothelioma or pleural metastases resulting in low perioperative morbidity and mortality as well as remarkable local tumor control.