Epithelioid Malignant Pleural Mesothelioma Research Articles

Integration of the PD-L1 inhibitor atezolizumab and WT1/DC vaccination into standard-of-care first-line treatment for patients with epithelioid malignant pleural mesothelioma-Protocol of the Immuno-MESODEC study.

Malignant pleural mesothelioma (MPM) is an aggressive cancer with a very poor prognosis. Recently, immune checkpoint inhibition (ICI) has taken center stage in the currently ongoing revolution that is changing standard-of-care treatment for several malignancies, including MPM. As multiple arguments and accumulating lines of evidence are in support of the existence of a therapeutic synergism between chemotherapy and immunotherapy, as well as between different classes of immunotherapeutics, we designed a multicenter, single-arm, phase I/II trial in which both programmed-death-ligand 1 (PD-L1) inhibition and dendritic cell (DC) vaccination are integrated in the first-line conventional platinum/pemetrexed-based treatment scheme for epithelioid MPM patients (Immuno-MESODEC, ClinicalTrials.gov identifier NCT05765084). Fifteen treatment-naïve patients with unresectable epithelioid subtype MPM will be treated with four 3-weekly (±3 days) chemo-immunotherapy cycles. Standard-of-care chemotherapy consisting of cisplatinum (75mg/m2) and pemetrexed (500mg/m2) will be supplemented with the anti-PD-L1 antibody atezolizumab (1200 mg) and autologous Wilms' tumor 1 mRNA-electroporated dendritic cell (WT1/DC) vaccination (8-10 x 106 cells/vaccination). Additional atezolizumab (1680 mg) doses and/or WT1/DC vaccinations (8-10 x 106 cells/vaccination) can be administered optionally following completion of the chemo-immunotherapy scheme. Follow-up of patients will last for up to 90 days after final atezolizumab administration and/or WT1/DC vaccination or 24 months after diagnosis, whichever occurs later. The trial's primary endpoints are safety and feasibility, secondary endpoints are clinical efficacy and immunogenicity. This phase I/II trial will evaluate whether addition of atezolizumab and WT1/DC vaccination to frontline standard-of-care chemotherapy for the treatment of epithelioid MPM is feasible and safe. If so, this novel combination strategy should be further investigated as a promising advanced treatment option for this hard-to-treat cancer.

Abstract 4085: The anti-VISTA x MSLN bispecific antibody-interferon beta mutein fusion protein: A trispecific immunocytokine with potent therapeutic efficacy against malignant pleural mesothelioma

Abstract Background Malignant pleural mesothelioma (MPM) is a rare and highly fatal cancer primarily induced by asbestos exposure. The 5-year overall survival rate for MPM patients is less than 20%. Before the FDA approval of the combination of immune checkpoint inhibitors (Nivolumab + Ipilimumab, CHECKMATE-743), chemotherapy was the only systemic therapy for MPM. However, the predominant histological type of MPM, epithelioid MPM, comprising approximately 70% of cases, showed limited clinical benefits from immune checkpoint inhibitors when compared to non-epithelioid histology. Consequently, there is an unmet medical need to develop a new anti-cancer drug specifically for the treatment of epithelioid MPM. In this study, we discovered that V-domain Ig suppressor of T cell activation (VISTA), an immune checkpoint protein, and Mesothelin (MSLN), a tumor differentiation antigen, are co-expressed in epithelioid MPM. Subsequently, we developed a biomarker-based anti-VISTA x MSLN bispecific antibody (BsAb) and anti-VISTA x MSLN BsAb-IFN-β mutein fusion protein (trispecific immunocytokine) for the treatment of epithelioid MPM. Method We designed and screened various structures of the anti-VISTA x MSLN BsAb. To produce the trispecific immunocytokine, we fused IFN-β mutein (R27T/C17S), which exhibits improved stability, productivity, and pharmacokinetic properties compare to recombinant IFN-β. The in vitro efficacy of the trispecific immunocytokine was tested in human MPM cell lines, and its in vivo efficacy was evaluated in a human MPM xenograft mouse model and a human IFNAR1/2 Knock-in (KI) mouse model. Results We demonstrated a strong positive correlation between the expression levels of VISTA and MSLN in epithelioid MPM. The Anti-VISTA x MSLN BsAb showed improved binding affinity and antibody-dependent cell cytotoxicity (ADCC) activity. The trispecific immunocytokine displays analogous biological activities to both Anti-VISTA x MSLN BsAb and IFN-β mutein. The trispecific immunocytokine exhibited potent in vivo and in vitro anti-cancer activities against epithelioid MPM preclinical models, operating through both direct cytotoxicity and indirect activation of immune cells. Conclusion The trispecific immunocytokine demonstrated robust in vitro and in vivo anti-cancer efficacy in the epithelioid MPM model. Our findings suggest that the trispecific immunocytoine is a promising drug candidate for epithelioid MPM. Citation Format: Hee Geon Park, Hyeon Ju Kim, Myeung Ryun Seo, Ji Eun Park, Tae Won Kim, Jeung Hoo Choi, Jay Park, Kyoung Song, Chan Gyu Lee, Hae Min Jeong, Jun Young Choi, Yeong Jeong Jeon, Yoon La Choi, Sung Youl Hong, Young Kee Shin. The anti-VISTA x MSLN bispecific antibody-interferon beta mutein fusion protein: A trispecific immunocytokine with potent therapeutic efficacy against malignant pleural mesothelioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4085.

163P Decoding the tumor immune microenvironment to unleash effective immunotherapy avenues for epithelioid malignant pleural mesothelioma

163P Decoding the tumor immune microenvironment to unleash effective immunotherapy avenues for epithelioid malignant pleural mesothelioma

Impact of guideline therapy on survival of patients with stage I-III epithelioid mesothelioma.

Modern treatment guidelines recommend multimodal therapy with at least chemotherapy and surgery for patients with potentially resectable epithelioid mesothelioma. This study evaluated guideline compliance for patients with stage I-III epithelioid mesothelioma and tested the hypothesis that guideline-concordant therapy improved survival. The National Cancer Database was queried for patients with stage I-III epithelioid malignant pleural mesothelioma between 2004 and 2016. The impact of therapy was evaluated using logistic regression, Kaplan-Meier analysis, Cox-proportional hazards analysis, and propensity-scoring methods. During the study period, guideline-concordant therapy was used in 677 patients (19.1%), and 2,857 patients (80.8%) did not have guideline-concordant therapy. Younger age, being insured, living in a census tract with a higher income, clinical stage, and being treated at an academic or research program were all predictors of receiving guideline-concordant therapy in multivariable analysis. Guideline-concordant therapy yielded improved median survival [24.7 (22.4-26.1) vs. 13.7 (13.2-14.4) months] and 5-year survival [17.7% (14.7-21.3%) vs. 8.0% (7.0-9.3%)] (P<0.001), and continued to be associated with better survival in both multivariable analysis and propensity-matched analysis. In the patients who received guideline therapy, median survival [24.9 (21.9-27.2) vs. 24.5 (21.7-28.1) months] and 5-year survival [14.9% (10.9-20.2%) vs. 20.1% (16.0-25.4%)] was not significantly different between patients who underwent induction (n=304) versus adjuvant (n=373) chemotherapy (P=0.444). Guideline-concordant therapy for potentially resectable epithelioid mesothelioma is associated with significantly improved survival but used in a minority of patients. The timing of chemotherapy with surgery in this study did not have a significant impact on overall survival.

Real-life efficacy of nivolumab plus ipilimumab combination in untreated, unresectable malignant pleural mesotheliomas: Result of French early access program—MESOIMMUNE – GFPC 04-2021.

8536 Background: The SOC for unresectable malignant pleural mesothelioma (MPM) has changed in 2020 with the combination nivolumab plus ipilimumab (NIVO+IPI) results of CheckMate 743 study. As CheckMate 743 was therapeutic trial in selected MPM patients (pts), additional data would be of interest to confirm the results in real-life setting. Methods: The present multicenter, retrospective study assessed the outcomes of NIVO+IPI, via an early access program (EAP) in France, in pts with treatment naïve unresectable MPM. The primary objective was investigator-assessed real world progression-free survival (rwPFS) from initiation of NIVO+IPI, defined as time from first dose of NIVO+IPI to first documentation of objective disease progression or death from any cause. The secondary objectives were real world OS (rwOS), objective response rate (ORR), and safety of NIVO+IPI combination. Results: From April 1, 2021 to Feb 15, 2022 (last day of EAP) there were 143 pts included out of 350 pts treated by EAP for unresectable MPM in 44 centers. Population characteristics are described in the table. With a median follow-up of 14.1 months, median rwPFS was 7.8 months (95%CI 6.2-9.5). rwPFS rates no differ according to histological subtypes: rwPFS for epithelioid MPM was 8.1 months (95%CI 6.0-12.6) and 7.4 months (95% CI 5.3-11.2) for other histological subtypes. The median rwOS was not reached (NR), 1-year survival rate was 65% (95% CI 57-75%). Median rwOS was NR and 13.1 (95% CI 7.8- NA) in epithelioid and non-epithelioid MPM, respectively. At 1 year, 71.2% of pts with epithelioid MPM are still alive versus 51.2% in pts with other histological subtypes. ORR was 23.9% (95% CI 16.9-32.0%) with median time to response of 3.68 months (2.33-5.09) after introduction of NIVO+IPI. Disease control rate was 80.4%. Grade 3-4 adverse events (AE) occurred in 37.8%. Severe immune-related AE occurred in 13.9% of patients. Five deaths were associated with treatment-related AEs according to investigators judgment. Conclusions: While pt’s characteristics differed from the pivotal trial, notably with older and unselected patients, efficacy outcomes that we observed here compares favorably with CheckMate 743 results. Tolerance looks acceptable in real-life setting despite 5 toxic deaths reported. Extended follow-up of our cohort will allow consolidation of the results. Clinical trial information: NCT05308966 . [Table: see text]

CDKN2A/p16 evaluation in cytology specimens.

CDKN2A/p16 evaluation in cytology specimens.

KRAS Mutations Are Associated with Shortened Survival in Patients with Epithelioid Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive malignancy of the pleural surface that includes three major histologic subtypes, epitheliod, sarcomatoid and biphasic. Epithelioid mesothelioma is usually associated with better prognosis. The genetic mechanisms driving MPM, the possible target mutations and the correlation with overall survival remain largely unsettled. We performed target exome sequencing in 29 cases of MPM aimed at identifying somatic mutations and, eventually, their correlation with phenotypic traits and prognostic significance. We found that KRAS mutations, occurring in 13.7% of cases, were associated with shortened median survival (7.6 versus 32.6 months in KRAS wild-type; p = 0.005), as it was the occurrence of any ≥3 mutations (7.6 versus 37.6 months; p = 0.049). Conversely, the presence of KDR single nucleotide polymorphism p.V297I (rs2305948) resulted in a favorable variable for survival (NR versus 23.4 months; p = 0.026). With the intrinsic limitations of a small number of cases and patient heterogeneity, results of this study contribute to the characterization of the mutation profile of MPM and the impact of selected somatic mutations, and possibly KDR polymorphism, on prognosis.

Importance of Histopathological Grading for Treatment Selection in Malignant Mesothelioma.

Complexities in TNM staging in epithelioid malignant pleural mesothelioma (MPM) may lead to errors in treatment selection, leading to major surgical interventions in patients with low survival expectations. Sixty-nine stage I epithelioid MPM patients, including 27 patients treated with pleurectomy/decortication (P/D) and multimodal therapy (MMT) (the P/D [MMT] group), and 42 patients treated with chemotherapy or chemoradiotherapy (the CRT group), were included in the study. After an initial evaluation of overall survival, all patients were grouped in terms of histopathological parameters and treatment types, and then, a secondary survival evaluation was performed for the groups. Forty-one patients were male, the mean age was 61.8 years. The median survival time was 26 months in the P/D (MMT) group, and 19.6 months in the CRT group, but the difference was not statistically significant. After grouping according to pathological criteria, a median survival time of 32.4 ± 2.9 months in the P/D (MMT) group and 21.9 ± 3.2 months in the CRT group was obtained among patients with histopathological low-grade tumors. Among patients with high-grade tumors, the median survival time was 18.3 ± 2.6 months in the P/D (MMT) group and 17 ± 4.4 months in the CRT group. Among patients with low-grade tumors, the P/D (MMT) group had longer survival. Median survival times were similar among patients with high-grade tumors. In epithelioid MPM, histopathological grading by video-assisted thoracic surgery pleural biopsy can prove accurate in selecting patients for P/D and MMT.

An Investigation of Cancer-Directed Surgery for Different Histologic Subtypes of Malignant Pleural Mesothelioma

The role of cancer-directed surgery in the treatment of stage I-IIIA malignant pleural mesothelioma (MPM) by histologic subtypes remains controversial. The objective of this study was to evaluate the survival of the different histologic subtypes for stage I-IIIA MPM stratified by cancer-directed surgery and nonoperative management. How is the histologic subtype of MPM, clinical stage of MPM, and use of cancer-directed surgery for MPM associated with overall survival? Overall survival of patients with stage I-IIIA epithelioid, sarcomatoid, and biphasic MPM in the National Cancer Database from 2004 through 2017 who underwent cancer-directed surgery (ie, surgery with or without chemotherapy or radiation) or chemotherapy with or without radiation (nonoperative management) was evaluated using Kaplan-Meier analysis, multivariate Cox proportional hazards analysis, and propensity score-matched analysis. Of 2,285 patients with stage I-IIIA MPM who met inclusion criteria, histologic subtype was epithelioid in 71%of patients, sarcomatoid in 12%of patients, and biphasic in 17%of patients. Median survival was 20months in the epithelioid group, 8months in the sarcomatoid group, and 13months in the biphasic group (P< .01). Among patients who underwent surgery, median survival was 25months in the epithelioid group, 8months in the sarcomatoid group, and 15months in the biphasic group (P< .01). In multivariate Cox proportional hazards analyses, surgery was associated with improved survival in the epithelioid group (P< .01) but not in the sarcomatoid (P= .63) or biphasic (P= .21) groups. These findings were consistent in propensity score-matched analyses for each MPM histologic type. In this national analysis, cancer-directed surgery was found to be associated with improved survival for stage I-IIIA epithelioid MPM, but not for biphasic or sarcomatoid MPM.

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

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. 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. 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. 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.

What's Current and What's New in Mesothelioma?

Malignant mesothelioma is a rare disease with limited treatment options. In malignant pleural mesothelioma (MPM), radical trimodality approaches, including surgery, radiotherapy and systemic chemo- and immunotherapy, have been delivered in some countries but remain controversial due to a lack of randomised evidence. Even in the unresectable scenario, surgery and radiotherapy play an important role in managing pleural effusions and pain, which may optimise wellbeing and maintain performance status. From the systemic treatment point of view, the recent incorporation of anti-angiogenics and, more importantly, immunotherapy has changed the standard of care in a space where chemotherapy with platinum and pemetrexed was the only therapeutic intervention with demonstrated benefits in overall survival. Histology is essential in determining an initial treatment plan as non-epithelioid MPMs may have a higher substantial survival improvement with dual immunotherapy compared with chemotherapy, whereas chemotherapy remains an option for epithelioid MPM; however, predictive biomarkers for systemic therapy are not entirely validated to guide the selection, as a subgroup of MPM patients might not benefit from immunotherapy. This overview approaches how the overall management of mesothelioma is evolving to incorporate the recent changes in the standards of care.

Define the Two Molecular Subtypes of Epithelioid Malignant Pleural Mesothelioma.

Malignant pleural mesothelioma (MPM) is a fatal disease of respiratory system. Despite the availability of invasive biomarkers with promising results, there are still significant diagnostic and therapeutic challenges in the treatment of MPM. One of three main mesothelioma cell types, epithelioid mesothelioma makes up approximately 70% of all mesothelioma cases. Different observational findings are under process, but the molecular heterogeneity and pathogenesis of epithelioid malignant pleural mesothelioma (eMPM) are still not well understood. Through molecular analysis, expression profiling data were used to determine the possibility and optimal number of eMPM molecular subtypes. Next, clinicopathological characteristics and different molecular pathways of each subtype were analyzed to prospect the clinical applications and advanced mechanisms of eMPM. In this study, we identified two distinct epithelioid malignant pleural mesothelioma subtypes with distinct gene expression patterns. Subtype I eMPMs were involved in steroid hormone biosynthesis, porphyrin and chlorophyll metabolism, and drug metabolism, while subtype II eMPMs were involved in rational metabolism, tyrosine metabolism, and chemical carcinogenesis pathways. Additionally, we identified potential subtype-specific therapeutic targets, including CCNE1, EPHA3, RNF43, ROS1, and RSPO2 for subtype I and CDKN2A and RET for subtype II. Considering the need for potent diagnostic and therapeutic biomarkers for eMPM, we are anticipating that our findings will help both in exploring underlying mechanisms in the development of eMPM and in designing targeted therapy for eMPM.

EP07.01-002 Surgery in Stage I-III Malignant Pleural Mesothelioma: A Surveillance, Epidemiology, and End Results (SEER)- Medicare Analysis 1995-2015

Malignant pleural mesothelioma (MPM) is a rare and aggressive malignancy with very poor prognosis. Histology (epithelioid, biphasic and sarcomatoid) has important prognostic implications. Although radical surgery (RS) has been recommended in resectable epithelioid MPM patients, whether RS is associated with improved overall survival (OS) is inconclusive due to lack of data from randomized clinical trials, and the optimal treatment paradigm remains unclear.

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.

Second Surgery for Recurrent Malignant Pleural Mesothelioma after Multimodality Treatment: A Systematic Review.

Malignant pleural mesothelioma (MPM) is an aggressive asbestos-related tumour with poor prognosis. To date, a multimodality treatment, including chemotherapy and surgery, with or without radiotherapy, is the gold standard therapy for selected patients with epithelioid and early-stage MPM. In this setting, the goal of surgery is to achieve the macroscopic complete resection, obtained by either extrapleural pneumonectomy or pleurectomy/decortication. Failure, in local and/or distant sites, is one of the major concerns; in fact, there has been no established treatment for the recurrence of MPM after the multimodal approach, and the role of surgery in this context is still controversial. By using electronic databases, studies that included recurrent MPM patients who underwent a second surgery were identified. The endpoints included were: a pattern of recurrence, post-recurrence survival (PRS), and the type of second surgery. When available, factors predicting better PRS and perioperative mortality and morbidity were collected. This systematic review offers an overview of the results that are currently obtained in patients undergoing a second surgery for relapsed MPM, with the aim to provide a comprehensive view on this subject that explores if a second surgery leads to an improvement in survival.

68 Ga-FAPI-04 Versus 18 F-FDG PET/CT in Detection of Epithelioid Malignant Pleural Mesothelioma.

We describe 68 Ga-FAPI (fibroblast activation protein inhibitor)-04 and 18 F-FDG PET/CT findings in a case with epithelioid malignant pleural mesothelioma. Compared with 18 F-FDG PET/CT, 68 Ga-FAPI-04 PET/CT more clearly showed the pleural tumors and lymph node metastases and detected more pleural lesions because the tumors showed higher 68 Ga-FAPI-04 activity. This case indicates that 68 Ga-FAPI-04 PET/CT may be a promising new tool in evaluation of malignant pleural mesothelioma, which needs further investigation.

20 years managing malignant pleural mesothelioma: a review of our experience and the quest for the optimal prognostic marker

Introduction: Malignant pleural mesothelioma (MPM) is a rare, but aggressive incurable cancer. A variety of prognostic tools have been developed to guide clinicians and patients in the management of MPM regarding the most appropriate therapy and survival time. Objectives: To evaluate the usefulness of the Brims’ decision tree analysis, the EORTC prognostic score, the CALGB prognostic groups, the modified Glasgow Prognostic Score (mGPS), and the LENT prognostic score in our MPM patients. Methods: Local retrospective database analysis of patients with MPM diagnosed between 2000 and 2020. The different prognostic scores were applied and MPM group risks’ evolution was analyzed. Statistical analysis was performed with IBM® SPSS® Statistics 25. Results: A total of 67 patients were evaluated (55 males, 82.1%). Epithelioid MPM was the commonest histological type (51 patients, 76.1%). Median overall survival (OS) was 11 months (IQR 23) and median progression free-survival (PFS) was 7 months (IQR 12.5). Survival distributions were statistically significantly different for the Brims’ and the mGPS’ groups (respectively, χ2 = 7.188, p = .027, and χ2 = 6.46, p = .04). For EORTC, CALGB and LENT score, there were not statistically significant differences in survival distributions (respectively, χ2 =.57, p = .811; χ2 = 7.978, p = .157; and χ2 = 1.23, p = .267). Brims’ model and mGPS statistically significantly predicted OS (respectively, F(1,57) = 11.1, p &lt; 0.01, and F(1,32) = 6.846, p = .01). EORTC, CALGB and LENT failed to statistically significantly predict OS (respectively, F(1,44) = .003, p = .955; F(1.43) = .722, p = 0.4; and F(1,14) = 1.193, p = .293). Conclusion: The small number of patients included and missing data for some parameters are limitations of our analysis. However, to our knowledge, this was the first study and the largest cohort to address MPM prognostic scores in our country. In our cohort, the Brims’ model and mGPS were useful in predicting survival. Both are simple tools with easily accessible parameters and should be considered for clinical practice.

Impact of Mesothelioma Histologic Subtype and Use of Cancer-Directed Surgery on Outcomes in the National Cancer Database

<h3>Purpose/Objective(s)</h3> To evaluate the impact of malignant pleural mesothelioma (MPM) histology subtype and the use of surgery on overall survival. <h3>Materials/Methods</h3> Multivariable Cox proportional hazards modeling and propensity score-matched analysis was performed to evaluate the overall survival of patients with stage I-IIIA MPM who underwent cancer-directed surgery or nonoperative management stratified by subtype of MPM. Patients who were coded in the National Cancer Database (NCDB) as not having undergone surgery because surgery "was contraindicated due to patient risk factors (comorbid conditions, advanced age, progression of tumor prior to planned surgery, etc.)" were excluded from analysis. <h3>Results</h3> Of 6,778 patients who had stage I–IIIA MPM during the study period, histologic subtype was epithelioid in 4,783 patients (70%), sarcomatoid in 1,060 patients (16%), and biphasic in 935 patients (14%). Median survival was 17 months in the epithelioid group, 5 months in the sarcomatoid group, and 11 months in the biphasic group (<i>P</i> < 0.01). Among patients who underwent surgery, median survival was 26 months in the epithelioid group, 9 months in the sarcomatoid group, and 15 months in the biphasic group (<i>P</i> < 0.01). In multivariable analysis, cancer-directed surgery was associated with improved survival in the epithelioid (adjusted hazard ratio [aHR] 0.75 [95% CI: 0.68-0.82]; <i>P</i> < 0.01) and biphasic (aHR 0.78 [95% CI: 0.64-0.95]; <i>P</i> = 0.02) groups but not in the sarcomatoid (aHR 0.82 [95% CI: 0.64-1.05]; <i>P</i> = 0.11) group, when compared to nonoperative management. Propensity-score matching was used to create 2 groups of 725, 109, and 174 patients with epithelioid, sarcomatoid, and biphasic MPM, respectively, each of whom received cancer-directed surgery or nonoperative management and were well-matched with regard to 12 common prognostic covariates including comorbidities, clinical stage, and T and N status. Surgery was associated with improved median survival in the epithelioid (21.9 months [95% CI: 20.1-23.9] vs. 16.8 months [95% CI: 15.4-17.8]; <i>P</i> < 0.01) and biphasic (12.2 months [95% CI: 11.3-14.6] vs. 10.7 months [95% CI: 9.5-11.9]; <i>P</i> < 0.01) groups but not in the sarcomatoid (7.8 months [95% CI: 6.2-11.7] vs. 6.9 months [95% CI: 6.0-7.9]; <i>P</i> < 0.01) group. <h3>Conclusion</h3> In this national analysis, we found that cancer-directed surgery is associated with significantly improved survival for stage I-IIIA MPM patients with epithelioid and biphasic histologies. Patients with sarcomatoid histology have poor prognosis and do not benefit from cancer-directed surgery. Our findings support current National Comprehensive Cancer Network (NCCN) guidelines recommending surgery for only epithelioid and biphasic histologies.

Butein-instigated miR-186-5p-dependent modulation of TWIST1 affects resistance to cisplatin and bioenergetics of Malignant Pleural Mesothelioma cells.

Aim: Malignant pleural mesothelioma is a chemoresistant tumor, and biphasic and sarcomatoid histologies portend the worst prognosis for malignant pleural mesothelioma (MPM) patients. We obtained the microRNA expression profile of three biphasic-sarcomatoid MPM cell lines to identify commonly expressed microRNAs and evaluate the effect of butein, a chemo-sensitizing compound, on this microRNA subset. Methods: Nanostring-based microRNA profiling and analysis through the ROSALIND platform were employed to identify the commonly modulated microRNAs and their targets. MicroRNA-mimic transfection, Luciferase assay, and Western blotting were employed to show specific perturbation of TWIST1 levels by miR-186-5p. Sphere-forming assays, invasion assay, and metabolic profiling were used to assess the biological consequences of the butein-instigated miR-186-5p-mediated perturbation of TWIST1 levels. TGCA analysis was used to search for the correlation between TWIST1 and miR-186-5p levels in biphasic and epithelioid MPM specimens. Results: We identified a set of perturbed microRNAs, common to three biphasic/sarcomatoid MPM cell lines, after butein treatment. When focusing on miR-186-5p, we unraveled a butein-ignited and miR-186-5p-mediated modulation of TWIST1 levels which affected the 3D anchorage-independent growth, cisplatin resistance, invasion, and bioenergetics of the MPM cell lines tested. We showed that miR-186-5p and TWIST1 levels are anti-correlated in biphasic MPM specimens from TCGA. Conclusion: We unraveled a novel mechanism of action of butein, which attenuated the pro-tumorigenic features of MPM at least through a miR-186-5p-TWIST1 axis. We suggest that those activities converge into the chemo-sensitizing effect of this compound and may be of translational relevance.

Epigenetic Immune Remodeling of Mesothelioma Cells: A New Strategy to Improve the Efficacy of Immunotherapy.

Malignant pleural mesothelioma (MPM) is an aggressive malignancy with a severe prognosis, and with a long-standing need for more effective therapeutic approaches. However, treatment with immune checkpoint inhibitors is becoming an increasingly effective strategy for MPM patients. In this scenario, epigenetic modifications may negatively regulate the interplay between immune and malignant cells within the tumor microenvironment, thus contributing to the highly immunosuppressive contexture of MPM that may limit the efficacy of immunotherapy. Aiming to further improve prospectively the clinical efficacy of immunotherapeutic approaches in MPM, we investigated the immunomodulatory potential of different classes of epigenetic drugs (i.e., DNA hypomethylating agent (DHA) guadecitabine, histone deacetylase inhibitors VPA and SAHA, or EZH2 inhibitors EPZ-6438) in epithelioid, biphasic, and sarcomatoid MPM cell lines, by cytofluorimetric and real-time PCR analyses. We also characterized the effects of the DHA, guadecitabine, on the gene expression profiles (GEP) of the investigated MPM cell lines by the nCounter platform. Among investigated drugs, exposure of MPM cells to guadecitabine, either alone or in combination with VPA, SAHA and EPZ-6438 demonstrated to be the main driver of the induction/upregulation of immune molecules functionally crucial in host-tumor interaction (i.e., HLA class I, ICAM-1 and cancer testis antigens) in all three MPM subtypes investigated. Additionally, GEP demonstrated that treatment with guadecitabine led to the activation of genes involved in several immune-related functional classes mainly in the sarcomatoid subtype. Furthermore, among investigated MPM subtypes, DHA-induced CDH1 expression that contributes to restoring the epithelial phenotype was highest in sarcomatoid cells. Altogether, our results contribute to providing the rationale to develop new epigenetically-based immunotherapeutic approaches for MPM patients, potentially tailored to the specific histologic subtypes.