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Simple Summary: Malignant pleural mesothelioma poses a significant diagnostic challenge for pathologists, requiring a comprehensive multidisciplinary approach. Diagnosis relies on morphological, immunohistochemical, and sometimes molecular assessments, integrated with clinical and radiological findings. The first diagnostic challenge is distinguishing MPM from metastatic pleural lesions or benign mesothelial proliferations. Immunohistochemical markers such as podoplanin, WT1, calretinin, and HEG1 are pivotal, though none is entirely specific. In the same way, BAP1 and MTAP provide enhanced sensitivity and specificity for differentiating malignant from benign conditions and, in more complex cases, molecular tests can detect valuable genetic alterations. The International Mesothelioma Interest Group regularly updates its guidelines to optimize and refine diagnostic processes. The aim is to enhance diagnostic precision and improve the clinical management of MPM. Malignant pleural mesothelioma (MPM) still represents a complex diagnostic challenge for pathologists in routine practice. This diagnosis requires a multidisciplinary approach, and pathological evaluation is mandatory. The histopathological diagnosis is stepwise and should be based on morphological and immunohistochemical assessment, sometimes associated with molecular tests, and supported by clinical and radiological findings. A correct morphological approach aims to exclude pleural metastasis or benign mesothelial proliferations, which are the main differential diagnoses. While certain histological features are diagnostic of MPM, others are highly suggestive but not definitive. Immunohistochemistry plays a pivotal role, with a panel of both traditional and newer markers being used to assess mesothelial differentiation and to differentiate malignant from benign proliferations. In more challenging cases, molecular tests, such as fluorescent in situ hybridization (FISH) to detect CDKN2A deletion, can be helpful in distinguishing malignant from benign pleural lesions. This review summarizes the key morphological, immunohistochemical, and molecular features that should be considered when pleural biopsy samples are examined, with the aim of improving diagnostic accuracy in this complex area. [ABSTRACT FROM AUTHOR]

Simple Summary: Oncogene-driven non-small-cell lung cancer (NSCLC) is typically treated with targeted therapies to inhibit oncogene downstream signaling pathways and reduce tumor survival. The most common subtypes, EGFR and KRAS mutations, are amenable to these therapies; however, resistance often develops, leading to oncogene-independent metastases. This study explores non-oncogene addiction (NOA) as a novel strategy, targeting essential genes like ATR, which is involved in DNA damage response, and pyruvate dehydrogenase kinases (PDKs), which play a role in energy metabolism. Experiments were conducted using sensitive PC9 and the corresponding osimertinib-resistant cells (PC9/OR), namely EGFR-mutant H1975 and KRAS-mutant A549 cells treated with TKIs, alongside ATR and DCA inhibitors. The results indicated that combining these approaches could enhance efficacy compared to TKIs alone, suggesting a tailored strategy based on tumor subtype. This research underscores the potential of new therapeutic targets to improve treatment outcomes in patients with NSCLC compared to traditional TKI therapies. Background: Oncogene-driven NSCLC is usually treated with targeted therapies using tyrosine kinase inhibitors (TKIs) to inhibit oncogene downstream signaling pathways, affecting tumor survival and proliferation. EGFR- and KRAS-mutant NSCLCs are the most represented subtypes, and they are treated in clinical practice with oncogene-targeting drugs in the first and second line, respectively. Unfortunately, the development of oncogene-independent resistant clones limits TKI efficacy. Here, we used non-oncogene addiction (NOA) as an innovative therapeutic strategy to target other essential proteins that support changes in tumor phenotype. Specifically, we tested, for the first time, a combination of inhibitors, namely ATR, involved in DNA damage response, and pyruvate dehydrogenase kinases (PDKs), involved in energy metabolism. Methods: Sensitive PC9 and the corresponding EGFR-TKI-resistant PC9/OR, EGFR-mutant H1975, and KRAS-mutant A549 NSCLC cells, were treated with TKIs (osimertinib and selumetinib, respectively). In parallel, cells were exposed to two combination regimens: one using the TKI with an ATR inhibitor and the other one combining the two selected NOA inhibitors (ATR inhibitor, M4344; and PDK inhibitor, DCA). Results: The effect of these two combined approaches, compared to TKI alone, produced similar results in terms of cell proliferation, cell death, and migration. Thus, depending on tumor biology, selecting between the proposed therapeutic strategies will be different, to maximize tumor response. Conclusions: The major translational relevance of this study is to exploit new targets for the development of innovative and improved therapeutic strategies with NOA drugs, over combinations including target genes within the oncogene pathway, to overcome resistance to TKI therapies in patients with NSCLC who are oncogene-addicted. [ABSTRACT FROM AUTHOR]

Simple Summary: In the era of precision medicine and immunotherapy, the isolation and characterization of exosomes from the peripheral blood mononuclear cells (PBMC-EXs) of SCLC patients may represent a new tool to define responder (BR) from non-responder (NR) patients undergoing chemoimmunotherapy treatment. In this proof-of-concept study, we isolated PBMC-EXs from the peripheral blood of SCLC patients and investigated the potential role of such extracellular vesicles (EVs) in monitoring tumor response to drug stimuli. Interestingly, we found increased exosome levels of c-Myc and Snail along with reduced levels of the immune markers MAVS and STING in NR patients. Also, we showed that PBMC-EXs from BR patients induced an increase in apoptosis and a reduction in the cell viability of SCLC cells compared to PBMC-EXs from NR SCLC patients. Thus, we suggest that PBMC-EXs may represent an innovative strategy to be further explored for the therapy and selection of immune-responsive SCLC patients. Small cell lung cancer (SCLC) is a highly invasive and rapidly proliferating lung tumor subtype. Most patients respond well to a combination of platinum-based chemotherapy and PD-1/PDL-1 inhibitors. Unfortunately, not all patients benefit from this treatment regimen, and few alternative therapies are available. In this scenario, the identification of new biomarkers and differential therapeutic strategies to improve tumor response becomes urgent. Here, we investigated the role of exosomes (EXs) released from the peripheral blood mononuclear cells (PBMCs) of SCLC patients in mediating the functional crosstalk between the immune system and tumors in response to treatments. In this study, we showed that PBMC-EXs from SCLC patients with different responses to chemoimmunotherapy showed different levels of immune (STING and MAVS) and EMT (Snail and c-Myc) markers. We demonstrated that PBMC-EXs derived from best responder (BR) patients were able to induce a significant increase in apoptosis in SCLC cell lines in vitro compared to PBMC-EXs derived from non-responder (NR) SCLC patients. PBMC-EXs were able to affect cell viability and modulate apoptotic markers, DNA damage and the replication stress pathway, as well as the occurrence of EMT. Our work provides proof of concept that PBMC-EXs can be used as a tool to study the crosstalk between cancer cells and immune cells and that PBMC-EXs exhibit an in vitro ability to promote cancer cell death and reduce tumor aggressiveness. [ABSTRACT FROM AUTHOR]

Simple Summary: Multimodality treatment can improve outcome of malignant pleural mesothelioma (MPM) patients. However, the ideal scheme of combination of them is still unknown. We analyzed a case series of 17 patients treated at our institution with a sequence of induction chemotherapy, surgery, adjuvant radiotherapy and chemotherapy. Median overall survival was 32.1 months, median progression free survival was 23.7 months with a safe profile. These data according to our experience represent a great example of feasibility in clinical practice of three-modality four step approach and encourage further prospective studies to better define the details of treatment. Background: Multimodality treatment is considered the best treatment strategy for malignant pleural mesothelioma (MPM). However, the ideal combination of them is still a matter of controversy. Here, we report a case series of MPM treated with a trimodality approach: induction chemotherapy (CT), pleurectomy/decortication (P/D), postoperative radiotherapy (RT) and post-operative CT. Methods: A retrospective case series of 17 MPM patients treated between 2013 and 2020 is presented. Patients had epithelial or mixed MPM diagnosed by video-assisted thoracoscopy and pathologic IMIG stage I or II disease. Treatment details and radiological data were collected. Induction therapy consisted of combination of cisplatin and pemetrexed, every 21 days for two cycles. P/D was performed 4–6 weeks after induction CT, post-operative RT 3–6 weeks after surgery, while post-operative CT was given 4–6 weeks after RT, with the same schedule of induction. Results: All patients showed objective response or stability of disease at the restaging following induction CT and underwent surgery by posterolateral thoracotomy. There were two cases of cardiac arrest as major intraoperative complication, both resolved by manual cardiac massage. Minor complications included one hemidiaphragm elevation, 1 anemia requiring blood transfusion, one wound infection, and two persistent air leaks. Median overall survival was 32.1 months, median progression free survival was 23.7 months. Conclusions: These results suggest the feasibility of these trimodality treatment scheme for early stage MPM patients. Larger series and long-term prospective studies are needed to confirm the validity of this strategy. [ABSTRACT FROM AUTHOR]