BAP1 Loss, Nuclear Grading, and Nonepithelioid Features in the Diagnosis of Mesothelioma in Italy: Nevermore without the Pathology Report.

The pathologic diagnosis of pleural mesothelioma is generally based on international guidelines, but no compulsory points based on different drugs approvals in different European countries are required to be reported. According to the last (2021) edition of the World Health Organization classification of pleural tumors, the nuclear grade of epithelioid-type mesothelioma should be always inserted in the pathologic report, while the presence of BRCA-associated protein-1 (BAP1) (clone C4) loss and a statement on the presence of the sarcomatoid/nonepithelioid component are fundamental for both a screening of patients with suspected BAP1 tumor predisposition syndrome and the eligibility to perform first-line immunotherapy at least in some countries. Several Italian experts on pleural mesothelioma who are deeply involved in national scientific societies or dedicated working groups supported by patient associations agreed that the pathology report of mesothelioma of the pleura should always include the nuclear grade in the epithelioid histology, which is an overt statement on the presence of sarcomatoid components (at least 1%, in agreement with the last classification of pleural mesothelioma) and the presence of BAP1 loss (BAP1-deficient mesothelioma) or not (BAP1-retained mesothelioma) in order to screen patients possibly harboring BAP1 tumor predisposition syndrome. This review aims to summarize the most recent data on these three important elements to provide evidence regarding the possible precision needs for mesothelioma.

Pathological complete response in a patient with pleural mesothelioma treated with immunotherapy: a case report.

The role of immunotherapy in the multimodal treatment for pleural mesothelioma (PM) is still under investigation, particularly in the preoperative setting. Pathological complete response (pCR) has been previously described after chemotherapy and immunotherapy; however, there is no prior experience reported with immunotherapy alone before surgery. We report the case of a 58-year-old male with biphasic PM treated with immunotherapy, resulting in a major clinical partial response. Following a multidisciplinary evaluation between thoracic surgeons, medical oncologists, pathologists, radiologists and radiation oncologists, the patient underwent surgery with radical intent through a right extended pleurectomy/decortication (eP/D). Histopathological examination of the specimen confirmed a pathological Complete Response (pCR). This case supports the feasibility and potential efficacy of combining preoperative immunotherapy with surgery in the management of advanced PM.

Pegargiminase Plus First-Line Chemotherapy in Patients With Nonepithelioid Pleural Mesothelioma: The ATOMIC-Meso Randomized Clinical Trial.

Importance: Arginine deprivation using ADI-PEG20 (pegargiminase) combined with chemotherapy is untested in a randomized study among patients with cancer. ATOMIC-Meso (ADI-PEG20 Targeting of Malignancies Induces Cytotoxicity-Mesothelioma) is a pivotal trial comparing standard first-line chemotherapy plus pegargiminase or placebo in patients with nonepithelioid pleural mesothelioma. Objective: To determine the effect of pegargiminase-based chemotherapy on survival in nonepithelioid pleural mesothelioma, an arginine-auxotrophic tumor. Design, Setting, and Participants: This was a phase 2-3, double-blind randomized clinical trial conducted at 43 centers in 5 countries that included patients with chemotherapy-naive nonepithelioid pleural mesothelioma from August 1, 2017, to August 15, 2021, with at least 12 months' follow-up. Final follow-up was on August 15, 2022. Data analysis was performed from March 2018 to June 2023. Intervention: Patients were randomly assigned (1:1) to receive weekly intramuscular pegargiminase (36.8 mg/m2) or placebo. All patients received intravenous pemetrexed (500 mg/m2) and platinum (75-mg/m2 cisplatin or carboplatin area under the curve 5) chemotherapy every 3 weeks up to 6 cycles. Pegargiminase or placebo was continued until progression, toxicity, or 24 months. Main Outcomes and Measures: The primary end point was overall survival, and secondary end points were progression-free survival and safety. Response rate by blinded independent central review was assessed in the phase 2 portion only. Results: Among 249 randomized patients (mean [SD] age, 69.5 [7.9] years; 43 female individuals [17.3%] and 206 male individuals [82.7%]), all were included in the analysis. The median overall survival was 9.3 months (95% CI, 7.9-11.8 months) with pegargiminase-chemotherapy as compared with 7.7 months (95% CI, 6.1-9.5 months) with placebo-chemotherapy (hazard ratio [HR] for death, 0.71; 95% CI, 0.55-0.93; P = .02). The median progression-free survival was 6.2 months (95% CI, 5.8-7.4 months) with pegargiminase-chemotherapy as compared with 5.6 months (95% CI, 4.1-5.9 months) with placebo-chemotherapy (HR, 0.65; 95% CI, 0.46-0.90; P = .02). Grade 3 to 4 adverse events with pegargiminase occurred in 36 patients (28.8%) and with placebo in 21 patients (16.9%); drug hypersensitivity and skin reactions occurred in the experimental arm in 3 patients (2.4%) and 2 patients (1.6%), respectively, and none in the placebo arm. Rates of poststudy treatments were comparable in both arms (57 patients [45.6%] with pegargiminase vs 58 patients [46.8%] with placebo). Conclusions and Relevance: In this randomized clinical trial of arginine depletion with pegargiminase plus chemotherapy, survival was extended beyond standard chemotherapy with a favorable safety profile in patients with nonepithelioid pleural mesothelioma. Pegargiminase-based chemotherapy as a novel antimetabolite strategy for mesothelioma validates wider clinical testing in oncology. Trial Registration: ClinicalTrials.gov Identifier: NCT02709512.

Nivolumab in pretreated pleural mesothelioma: Results from an observational real-world study of patients treated within the AIFA 5% Fund.

BACKGROUND: Pleural mesothelioma is a rare cancer with a dismal prognosis and few therapeutic options, especially in the pretreated setting. Immunotherapy with checkpoint inhibitors as single agents yielded interesting results in refractory pleural mesothelioma, achieving a response rate between 10-20%, median progression-free survival of 2-5 months and median overall survival of 7-13 months. PATIENTS AND METHODS: A retrospective, multi-institutional study of pleural mesothelioma patients treated with nivolumab in second and further line was performed. The endpoints of the study are response rate, disease control rate, progression free survival and overall survival. RESULTS: Sixty-five patients with pleural mesothelioma treated with nivolumab in second and further line were enrolled at seven Italian institutions. The response rate was 8%, disease control rate was 37%, median progression free survival was 5.7 months (95% CI: 2.9-9.0) and median overall survival was 11.1 (95% CI 6.2-19.9) months. A higher neutrophils and neutrophils to lymphocytes ratio at baseline were associated with worse prognosis. CONCLUSION: Nivolumab as a single agent is fairly active in a cohort of unselected pretreated pleural mesothelioma patients. Further investigations on clinical and translational factors are needed to define which patient might benefit most from nivolumab treatment in pleural mesothelioma.

Impact of SARS-CoV-2 vaccines and recent chemotherapy on COVID-19 morbidity and mortality in patients with soft tissue sarcoma: an analysis from the OnCovid registry.

Background: To date, limited evidence exists on the impact of COVID-19 in patients with soft tissue sarcoma (STS), nor about the impact of SARS-CoV-2 vaccines and recent chemotherapy on COVID-19 morbidity and mortality in this specific population. Methods: We described COVID-19 morbidity and mortality among patients with STS across 'Omicron' (15 December 2021-31 January 2022), 'Pre-vaccination' (27 February 2020-30 November 2020), and 'Alpha-Delta' phase (01 December 2020-14 December 2021) using OnCovid registry participants (NCT04393974). Case fatality rate at 28 days (CFR28) and COVID-19 severity were also described according to the SARS-CoV-2 vaccination status, while the impact of the receipt of cytotoxic chemotherapy within 4 weeks prior to COVID-19 on clinical outcomes was assessed with Inverse Probability of Treatment Weighting (IPTW) models adjusted for possible confounders. Results: Out of 3820 patients, 97 patients with STS were included. The median age at COVID-19 diagnosis was 56 years (range: 18-92), with 65 patients (67%) aged < 65 years and most patients had a low comorbidity burden (65, 67.0%). The most frequent primary tumor sites were the abdomen (56.7%) and the gynecological tract (12.4%). In total, 36 (37.1%) patients were on cytotoxic chemotherapy within 4 weeks prior to COVID-19. The overall CFR28 was 25.8%, with 38% oxygen therapy requirement, 34% rate of complications, and 32.3% of hospitalizations due to COVID-19. CFR28 (29.5%, 21.4%, and 12.5%) and all indicators of COVID-19 severity demonstrated a trend toward a numerical improvement across the pandemic phases. Similarly, vaccinated patients demonstrated numerically improved CFR28 (16.7% versus 27.7%) and COVID-19 morbidity compared with unvaccinated patients. Patients who were on chemotherapy experienced comparable CFR28 (19.4% versus 26.0%, p = 0.4803), hospitalizations (50.0% versus 44.4%, p = 0.6883), complication rates (30.6% versus 34.0%, p = 0.7381), and oxygen therapy requirement (28.1% versus 40.0%, p = 0.2755) compared to those who were not on anticancer therapy at COVID-19, findings further confirmed by the IPTW-fitted multivariable analysis. Conclusion: In this study, we demonstrate an improvement in COVID-19 outcomes in patients with STS over time. Recent exposure to chemotherapy does not impact COVID-19 morbidity and mortality and SARS-CoV-2 vaccination confers protection against adverse outcomes from COVID-19 in this patient population.

An analysis from the OnCovid registry on the impact of chemotherapy and SARS-CoV-2 vaccines on clinical outcomes of patients with soft tissue sarcoma and COVID-19 Soft tissue sarcomas (STS) are a group of rare and aggressive tumours, usually treated with high dose cytotoxic chemotherapy. To date no clear evidence exists on the impact of COVID-19 in patients with STS, nor on the potential impact of recent chemotherapy and prior SARS-CoV-2 vaccination in this specific patient population. This is the 1st study to show COVID-19 outcomes in patients with STS, highlighting a substantial vaccine efficacy with no negative impact of recent chemotherapy on COVID-19 outcomes.

Clinical Next Generation Sequencing Application in Mesothelioma: Finding a Golden Needle in the Haystack.

Mesothelioma comprises a group of rare cancers arising from the mesothelium of the pleura, peritoneum, tunica vaginalis testis and pericardium. Mesothelioma is generally associated with asbestos exposure and has a dismal prognosis, with few therapeutic options. Several next generation sequencing (NGS) experiments have been performed on mesothelioma arising at different sites. These studies highlight a genomic landscape mainly characterized by a high prevalence (>20%) of genomic aberrations leading to functional losses in oncosuppressor genes such as BAP1, CDKN2A, NF2, SETD2 and TP53. Nevertheless, to date, evidence of the effect of targeting these alterations with specific drugs is lacking. Conversely, 1-2% of mesothelioma might harbor activating mutations in oncogenes with specifically approved drugs. The goal of this review is to summarize NGS applications in mesothelioma and to provide insights into target therapy of mesothelioma guided by NGS.

Pembrolizumab plus chemotherapy versus chemotherapy in untreated advanced pleural mesothelioma in Canada, Italy, and France: a phase 3, open-label, randomised controlled trial.

BACKGROUND: Pleural mesothelioma usually presents at an advanced, incurable stage. Chemotherapy with platinum-pemetrexed is a standard treatment. We hypothesised that the addition of pembrolizumab to platinum-pemetrexed would improve overall survival in patients with pleural mesothelioma. METHODS: We did this open-label, international, randomised phase 3 trial at 51 hospitals in Canada, Italy, and France. Eligible participants were aged 18 years or older, with previously untreated advanced pleural mesothelioma, with an Eastern Cooperative Oncology Group performance status score of 0 or 1. Patients were randomly assigned (1:1) to intravenous chemotherapy (cisplatin [75 mg/m2] or carboplatin [area under the concentration-time curve 5-6 mg/mL per min] with pemetrexed 500 mg/m2, every 3 weeks for up to 6 cycles), with or without intravenous pembrolizumab 200 mg every 3 weeks (up to 2 years). The primary endpoint was overall survival in all randomly assigned patients; safety was assessed in all randomly assigned patients who received at least one dose of study therapy. This trial is registered with ClinicalTrials.gov, NCT02784171, and is closed to accrual. FINDINGS: Between Jan 31, 2017, and Sept 4, 2020, 440 patients were enrolled and randomly assigned to chemotherapy alone (n=218) or chemotherapy with pembrolizumab (n=222). 333 (76 %) of patients were male, 347 (79%) were White, and median age was 71 years (IQR 66-75). At final analysis (database lock Dec 15, 2022), with a median follow-up of 16·2 months (IQR 8·3-27·8), overall survival was significantly longer with pembrolizumab (median overall survival 17·3 months [95% CI 14·4-21·3] with pembrolizumab vs 16·1 months [13·1-18·2] with chemotherapy alone, hazard ratio for death 0·79; 95% CI 0·64-0·98, two-sided p=0·0324). 3-year overall survival rate was 25% (95% CI 20-33%) with pembrolizumab and 17% (13-24%) with chemotherapy alone. Adverse events related to study treatment of grade 3 or 4 occurred in 60 (27%) of 222 patients in the pembrolizumab group and 32 (15%) of 211 patients in the chemotherapy alone group. Hospital admissions for serious adverse events related to one or more study drugs were reported in 40 (18%) of 222 patients in the pembrolizumab group and 12 (6%) of 211 patients in the chemotherapy alone group. Grade 5 adverse events related to one or more drugs occurred in two patients on the pembrolizumab group and one patient in the chemotherapy alone group. INTERPRETATION: In patients with advanced pleural mesothelioma, the addition of pembrolizumab to standard platinum-pemetrexed chemotherapy was tolerable and resulted in a significant improvement in overall survival. This regimen is a new treatment option for previously untreated advanced pleural mesothelioma. FUNDING: The Canadian Cancer Society and Merck & Co.

Epigenetic investigation into circulating microRNA 197-3p in sera from patients affected by malignant pleural mesothelioma and workers ex-exposed to asbestos.

The epigenetic role of microRNAs is established at both physiological and pathological levels. Dysregulated miRNAs and their targets appear to be a promising approach for innovative anticancer therapies. In our previous study, circulating miR-197-3p tested dysregulated in workers ex-exposed to asbestos (WEA). Herein, an epigenetic investigation on this circulating miRNA was carried out in sera from malignant pleural mesothelioma (MPM) patients. MiR-197-3p was quantified in MPM (n = 75) sera and comparatively analyzed to WEA (n = 75) and healthy subject (n = 75) sera, using ddPCR and RT-qPCR techniques. Clinicopathological characteristics, occupational, non-occupational information and overall survival (OS) were evaluated in correlation studies. MiR-197-3p levels, analyzed by ddPCR, were significantly higher in MPM than in WEA cohort, with a mean copies/µl of 981.7 and 525.01, respectively. Consistently, RT-qPCR showed higher miR-197-3p levels in sera from MPM with a mean copies/µl of 603.7, compared to WEA with 336.1 copies/µl. OS data were significantly associated with histologic subtype and pleurectomy. Circulating miR-197-3p is proposed as a new potential biomarker for an early diagnosis of the MPM onset. Indeed, miR-197-3p epigenetic investigations along with chest X-ray, computed tomography scan and spirometry could provide relevant information useful to reach an early and effective diagnosis for MPM.

Brief Report: Canadian Cancer Trials Group IND.227: A Phase 2 Randomized Study of Pembrolizumab in Patients With Advanced Malignant Pleural Mesothelioma (NCT02784171).

Immune checkpoint inhibitors have activity in mesothelioma. IND.227 was a phase 2 trial (120 patients planned) comparing progression-free survival of standard platinum and pemetrexed (CP) versus CP + pembrolizumab (pembro) versus pembro. Accrual to the pembro arm was discontinued on the basis of interim analysis (IA-16 wk disease control rate). CP + pembro was tolerable, with progression-free survival similar between arms and median survival and overall response rate higher than those of CP alone (19.8 mo [95% confidence interval or CI: 8.4-41.36] versus 8.9 mo [95% CI: 5.3-12.8] and 47% [95% CI: 24%-71%] versus 19% [95% CI: 5%-42%], respectively). The subsequent phase 3 trial has completed accrual; results are expected in 2023.

The Italian Experience in the Development of Mesothelioma Registries: A Pathway for Other Countries to Address the Negative Legacy of Asbestos.

Asbestos (all forms, including chrysotile, crocidolite, amosite, tremolite, actinolite, and anthophyllite) is carcinogenic to humans and causally associated with mesothelioma and cancer of the lung, larynx, and ovary. It is one of the carcinogens most diffuse in the world, in workplaces, but also in the environment and is responsible for a very high global cancer burden. A large number of countries, mostly with high-income economies, has banned the use of asbestos which, however, is still widespread in low- and middle-income countries. It remains, thus, one of the most common occupational and environmental carcinogens worldwide. Italy issued an asbestos ban in 1992, following the dramatic observation of a large increase in mortality from mesothelioma and other asbestos-related diseases in exposed workers and also in subjects with non-occupational exposure. A mesothelioma registry was also organized and still monitors the occurrence of mesothelioma cases, conducting a case-by-case evaluation of asbestos exposure. In this report, we describe two Italian communities, Casale Monferrato and Broni, that faced an epidemic of mesothelioma resulting from the production of asbestos cement and the diffuse environmental exposure; we present the activity and results of the Italian mesothelioma registry (ReNaM), describe the risk-communication activities at the local and national level with a focus on international cooperation and also describe the interaction between mesothelioma registration and medical services specialized in mesothelioma diagnosis and treatment in an area at high risk of mesothelioma. Finally, we assess the potential application of the solutions and methods already developed in Italy in a city in Colombia with high mesothelioma incidence associated with the production of asbestos-cement materials and the presence of diffuse environmental asbestos pollution.

Unprecedented long-term survival in a patient with malignant pleural mesothelioma treated with subsequent systemic chemo- and immunotherapeutic regimens.

Pleural mesothelioma is a rare disease with a dismal prognosis and few therapeutic options. Until recently the median overall survival for a pleural mesothelioma patient was up to 2 years, with few exceptional cases of patients achieving a longer survival. Here, we report the clinical case of a patient whose survival spanned over 10 years. The patient underwent several systemic treatments, including three different chemotherapy lines (cisplatin-pemetrexed, vinorelbine and platinum rechallenge) and two immunotherapy regimens using immune checkpoint inhibitors (anti CTLA-4 tremelimumab and anti PD-1 nivolumab). At the time this report was written, the patient was off-treatment, asymptomatic and with a stable radiological disease. Our case demonstrates that a prolonged survival with a preserved quality of life may be reached in selected patients through the exploitation of the available treatments in an expertise setting.

Immunotherapy of mesothelioma: the evolving change of a long-standing therapeutic dream.

Pleural mesothelioma (PM) is an aggressive and rare disease, characterized by a very poor prognosis. For almost two decades, the world standard treatment regimen for unresectable PM has consisted of a platinum-based drug plus pemetrexed, leading to an overall survival of approximately 12 months. The dramatic therapeutic scenario of PM has recently changed with the entry into the clinic of immune checkpoint inhibition, which has proven to be an effective approach to improve the survival of PM patients. The aim of the present review is to provide a comprehensive overview of the most promising immunotherapeutic-based strategies currently under investigation for advanced PM.

Transcription regulators and ultra-rare and other rare translocation-related sarcomas treated with trabectedin: A proof of principle from a post-hoc analysis.

Background: Among sarcomas, which are rare cancers with an incidence of <6 per 100.000/year cases, ultra-rare sarcomas have an incidence of approximately ≤1/1,000,000/year cases and altogether account for ~20% of all soft tissue sarcomas (STS) and bone sarcomas. The Italian Sarcoma Group has recently performed a non-interventional, retrospective TrObs study with data from 512 anthracycline-pretreated patients with advanced multiple STS histologies and treated with trabectedin (Palmerini, Cancers 2021; ClinicalTrials.gov Identifier: NCT02793050). Methods: A post-hoc analysis of case series to evaluate the efficacy and safety of trabectedin on patients with ultra-rare and other rare translocation-related sarcomas included in TrObs study was performed. Main outcomes comprised investigator-assessed overall response rate (ORR), disease control rate (DCR), progression-free survival (PFS) and safety. Results: Thirty-six patients (18 women) with ultra-rare and other rare sarcoma and a median age of 53.0 years (range: 22-81) were included. Most patients had solitary fibrous tumor (SFT; n=11) followed by epithelioid sarcoma (n=5), malignant peripheral nerve sheath tumor (MPNST; n=4), extraskeletal myxoid chondrosarcoma (EMC; n=3), desmoplastic small round cell tumor (DSRCT; n=3), and alveolar soft part sarcoma (ASPS), rhabdomyosarcoma and clear cell sarcoma (n=2 each). Thirty-five patients had metastatic disease and 23 patients received trabectedin as a second-line treatment. Among 35 patients evaluable for response, two patients with SFT and ASPS had a partial response and one patient with DSRCT obtained a complete response, reaching an ORR of 8.6% (95% CI: 2.8-23.4%). Among patients with an ORR, 6-months PFS was 100% in patients with ASPS, 45.7% in patients with SFT and 33.3% in those with DSRCT. Two patients with epithelioid sarcoma and myoepithelioma had disease stabilization lasting >24 months. Nine patients had at least one grade 3/4 adverse event, mostly being bone marrow toxicity (n=6). Conclusions: Trabectedin has some anti-tumor activity in some ultra-rare and other rare sarcomas, particularly translocation-related sarcomas, with the well-known manageable safety profile.

Preliminary validation of a brief PROM assessing psychological distress in patients with malignant mesothelioma: The mesothelioma psychological distress tool-Patients.

Objective: Psychological suffering in malignant mesothelioma (MM) differs from that in other cancers because of its occupational etiology, and we aimed to develop specific patient-reported outcome measures to assess it. Methods: We used a multi-method prospective observational multicentric study (N = 149), and a preliminary questionnaire validation was performed through a Bayesian approach. Results: Item analysis showed a good internal consistency and reliability (Cronbach alpha = 0.79 [95% CI = 0.74-0.93]. Twenty of the 41 initial items were selected as posterior 95% highest density interval factor loading standardized effect size fell outside of the region of practical equivalence. Bayesian exploratory factor analysis showed a two-factor structure: (1) Trauma-related reactions (TR, 13 items) and (2) Claim for justice (CJ, 7 items), confirmed by the Bayesian confirmatory factor analysis. Latent factors were poorly correlated (Posterior median: 0.13; 95% CI = -0.079 to 0.323). The 90% root mean square error of approximation posterior median was 0.04 [90% CI = 0.03-0.58]; the 90% chi-square posterior median was 242 [90% CI = 209-287]. Conclusion: Psychological suffering in MM patients implies negative cognitive, emotional, and somatic reactions related to the traumatic impact of the disease and the need to obtain justice through economic compensation. Our findings provide preliminary evidence that the Mesothelioma Psychological Distress Tool-Patients could be a promising and reliable instrument to assess MM patients' psychological distress.

Malignant eccrine spiradenocylindroma and parotid gland involvement in Brooke Spiegler syndrome.

Brooke-Spiegler syndrome is a rare disorder, characterized by the development of skin adnexal tumors, including cylindromas, trichoepitheliomas, spiradenomas. Although these neoplasms are benign in most patients, a malignant transformation can rarely occur. Furthermore, an occasional association between cutaneous adnexal tumors and basal cell adenoma as well as adenocarcinoma of the parotid gland has been rarely described, with approximately 20 cases reported. We report a case of BSS presenting with a malignant eccrine spiradenocylindroma, in a patient with previous history of parotid basal cell tumor.

Diagnostics of BAP1-Tumor Predisposition Syndrome by a Multitesting Approach: A Ten-Year-Long Experience.

Germline mutations in the tumor suppressor gene BRCA1-associated protein-1 (BAP1) lead to BAP1 tumor predisposition syndrome (BAP1-TPDS), characterized by high susceptibility to several tumor types, chiefly melanoma, mesothelioma, renal cell carcinoma, and basal cell carcinoma. Here, we present the results of our ten-year experience in the molecular diagnosis of BAP1-TPDS, along with a clinical update and cascade genetic testing of previously reported BAP1-TPDS patients and their relatives. Specifically, we sequenced germline DNA samples from 101 individuals with suspected BAP1-TPDS and validated pathogenic variants (PVs) by assessing BAP1 somatic loss in matching tumor specimens. Overall, we identified seven patients (7/101, 6.9%) carrying six different germline BAP1 PVs, including one novel variant. Consistently, cascade testing revealed a total of seven BAP1 PV carriers. In addition, we explored the mutational burden of BAP1-TPDS tumors by targeted next-generation sequencing. Lastly, we found that certain tumors present in PV carriers retain a wild-type BAP1 allele, suggesting a sporadic origin of these tumors or a functional role of heterozygous BAP1 in neoplastic development. Altogether, our findings have important clinical implications for therapeutic response of BAP1-TPDS patients.

Tumor treating fields affect mesothelioma cell proliferation by exerting histotype-dependent cell cycle checkpoint activations and transcriptional modulations.

Although clinical antitumor activity of Tumor Treating Fields (TTFields) has been reported in malignant pleural mesothelioma (MPM) patients, the mechanisms behind the different selectivity displayed by the various MPM histotypes to this physical therapy has not been elucidated yet. Taking advantage of the development of well characterized human MPM cell lines derived from pleural effusion and/or lavages of patients' thoracic cavity, we investigated the biological effects of TTFields against these cells, representative of epithelioid, biphasic, and sarcomatoid histotypes. Growth inhibition and cell cycle perturbations caused by TTFields were investigated side by side with RNA-Seq analyses at different exposure times to identify pathways involved in cell response to treatment. We observed significant differences of response to TTFields among the cell lines. Cell cycle analysis revealed that the most sensitive cells (epithelioid CD473) were blocked in G2M phase followed by formation of polyploid cells. The least sensitive cells (sarcomatoid CD60) were only slightly affected by TTFields with a general delay in all cell cycle phases. Apoptosis was present in all samples, but while epithelioid cell death was already observed during the first 24 h of treatment, sarcomatoid cells needed longer times before they engaged apoptotic pathways. RNA-Seq experiments demonstrated that TTFields induced a transcriptional response already detectable at early time points (8 h). The number of differentially expressed genes was higher in CD473 than in CD60 cells, involving several pathways, such as those pertinent to cell cycle checkpoints, DNA repair, and histone modifications. Our data provide further support to the notion that the antitumor effects of TTFields are not simply related to a non-specific reaction to a physical stimulus, but are dependent on the biological background of the cells and the particular sensitivity to TTFields observed in epithelioid MPM cells is associated with a higher transcriptional activity than that observed in sarcomatoid models.

Epithelioid Pleural Mesothelioma Is Characterized by Tertiary Lymphoid Structures in Long Survivors: Results from the MATCH Study.

Pleural mesothelioma (PM) is an aggressive tumor with few therapeutic options. Although patients with epithelioid PM (ePM) survive longer than non-epithelioid PM (non-ePM), heterogeneity of tumor response in ePM is observed. The role of the tumor immune microenvironment (TIME) in the development and progression of PM is currently considered a promising biomarker. A few studies have used high-throughput technologies correlated with TIME evaluation and morphologic and clinical data. This study aimed to identify different morphological, immunohistochemical, and transcriptional profiles that could potentially predict the outcome. A retrospective multicenter cohort of 129 chemonaive PM patients was recruited. Tissue slides were reviewed by dedicated pathologists for histotype classification and immunophenotype of tumor-infiltrating lymphocytes (TILs) and lymphoid aggregates or tertiary lymphoid structures (TLS). ePM (n = 99) survivors were further classified into long (>36 months) or short (<12 months) survivors. RNAseq was performed on a subset of 69 samples. Distinct transcriptional profiling in long and short ePM survivors was found. An inflammatory background with a higher number of B lymphocytes and a prevalence of TLS formations were detected in long compared to short ePM survivors. These results suggest that B cell infiltration could be important in modulating disease aggressiveness, opening a pathway for novel immunotherapeutic approaches.