Complex Target Volume Delineation and Treatment Planning in Radiotherapy for Malignant Pleural Mesothelioma (MPM)

Introduction: Radiotherapy alone or combined with surgery and/or chemotherapy is being investigated in the treatment of malignant pleural mesothelioma (MPM). This study aimed to simulate a Volumetric Modulated Arc Therapy (VMAT) treatment of a patient with MPM. Materials and Methods: CT images from a patient with intact lungs were imported via DICOM into the Pinnacle3 treatment planning (TP) system (TPS) and used as a model for MPM to delineate organs at risk (OAR) and both clinical and planning target volumes (CTV and PTV) with a margin of 5 mm. Elekta Synergy with 6 MV photons and 80 leafs MLCi2 was employed. VMAT plans were generated using two coplanar arcs with gantry rotation angles of 178° - 182°, the collimator angles of each arc were set to 90°, Octavius® 4D 729 was employed for quality assurance while the calculated and measured doses were compared using VeriSoft. Results: A TP was achieved. The Gamma volume analysis with criteria of 3 mm distance to agreement and 3% dose difference yielded the gamma passing rate = 99.9%. The reference isodose was 42.75 Gy with the coverage constraints for the PTV D95 and V95 = 95.0% of 45 Gy. The remaining dosimetric parameters met the recommendations from the clinically acceptable guidelines for the radiotherapy of MPM. Conclusion: Using well-defined TV and VMAT, a consistent TP compared to similar ones from publications was achieved. We obtained a high agreement between the 3D dose reconstructed and the dose calculated.

Malignant pleural mesothelioma:The disdained member of thoracic oncology!

Pleural mesothelioma is a very aggressive malignancy that arises from the pleural mesothelial cell lining and is linked strongly to prior asbestos exposure.The ban on asbestos has helped to lower the incidence,but in developing countries like India,it is expected to rise.It has an extended latency period usually progressing over decades and presents with nonspecific symptoms.It has a median survival ranging between 10-22 months.The diagnosis of malignant pleural mesothelioma is challenging and is done using computed tomography(CT),magnetic resonance imaging,or positron emission tomography-CT,with the last two predicting the resectability of the tumor better than CT alone.A pleural biopsy along with an array of immunohistochemical markers,such as p16,BRCA1 associated protein 1,and claudin-4,are required for a definitive diagnosis.Several genetic alterations have prognostic significance as well.The current histological subtype identification is indispensable for decision making because of the new therapeutic avenues being explored.The combination of nivolumab and ipilimumab-based immunotherapy outperformed platinum and pemetrexed-based chemotherapy in terms of survival benefit and improved quality of life especially for non-epithelioid subtypes.However,the latter continues to be a robust treatment option for patients with the epithelioid subtype.Surgery is recommended for resectable cases with radiotherapy being indicated in neoadjuvant,adjuvant,and palliative settings along with systemic treatment.This review article provides an overview of epidemiology,etiology,clinical manifestations,diagnostic approaches(including immunohistochemical and genetic markers),staging,and multidisciplinary approaches to current treatment for malignant pleural mesothelioma using surgery,chemotherapy,immunotherapy,and radiotherapy.It also sheds light on some recent studies(EMPHACIS,CALGB30901,Checkmate-743,etc.)that have led to significant developments in recent years with clinically meaningful results.

Malignant pleural mesothelioma mimics thoracic empyema: A case report

BACKGROUND Thoracic empyema and malignant pleural mesothelioma(MPM)are distinct medical conditions with similar symptoms,including cough,chest pain,and breathing difficulty.We present a rare MPM case mimicking thoracic empyema.Physicians must consider MPM risks for patients exposed to building material who exhibit lobulated pleural effusions,indicating thoracic empyema.CASE SUMMARY A 68-year-old retired male construction worker suffered from shortness of breath and chest tightness over 10 d,particularly during physical activity.A poor appetite and 4 kg weight loss over the past 3 wk were also reported.Chest images and laboratory data concluded a tentative impression of empyema thoracis(right).Video-assisted thoracic surgery with decortication and delobulation(right)was conducted.The pathological report yielded an MPM diagnosis.Refractory pleural bilateral effusions and respiratory failure developed postoperatively,and the patient died three weeks after the operation.CONCLUSION Thoracic empyema and MPM are distinct medical conditions that can present similar symptoms,and video-assisted thoracic surgery facilitates an accurate diagnosis.Empyema-mimicking presentations and postoperative refractory pleural effusion may indicate a poor MPM outcome.

Results of flexible 3D-conformal radiotherapy for patients with diffuse malignant pleural mesothelioma and comparative study of this technique with conventional radiotherapy

Objective： To observe the effects of the new technique of flexible 3D-conformal radiotherapy with combination of photon and electron （3DCRT） in the treatment of the patients with diffuse malignant pleural mesothelioma （MPM）, and carry out the comparative study between flexible 3DCRT and hemithoracic conventional radiotherapy （CRT）. Methods： From January 2004 to October 2007, 8 patients with MPM were treated with flexible 3DCRT. 5 patients had received cycles of chemotherapy before radiation. New technique of flexible 3DCRT with combination of photon and electron was used in our study, and DT 32.2-64 Gy with conventional split were delivered. CRT technique was mimicked to compare with 3DCRT technique to predict the possibility of lung damage in two methods. Results： One patient reached CR and other 7 patients got PR after radiation. Two patients died during the follow-up. The median survival time （MST） was 15.4 months and it was 18.8 months for sequential chemotherapy and radiotherapy group and 9.7 months for radiotherapy alone group. The V20, V30, and ipsilateral and contralateral median lung dosage （MLD） were 20.5%, 15.6%, 18.8 Gy and 2.2 Gy respectively when the flexible 3DCRT technique was used, whereas they were 36.8%, 27.9%, 31.1 Gy and 1.2 Gy respectively when the CRT technique was used. They were statistically different for the lung V20, V30 and ipsilateral MLD between the two techniques （P 〈 0.01）, whereas there was no different for the contralateral MLD （P = 0.08）. All patients received radiation were found to have lung fibrosis and classified as grades 1-2 radiation pneumonitis. The quality of life was increased from score 2.83 to 3.76 and it was significantly different （P 〈 0.01）. Conclusion： MPM is moderately sensitive to radiation. The flexible 3DCRT technique is feasible in the treatment of MPM and lung damage is reduced apparently comparing with the CRT technique. The quality of life of patients with MPM is improved after irradiation.

Intrathoracic latissimus dorsi muscle transposition: a reliable technique for prevention of bronchopleural fistula developing after extrapleural pneumonectomy and external beam radiotherapy in malignant pleural mesothelioma

Objective: Bronchopleural fistula (BPF) is a life threatening complication after pneumonectomy. Extra thoracic skeletal muscle transposition especially latissimus dorsi muscle flap (LDMF) had been used to prevent this complication. The aim of this study was to assess the effectiveness of LDMF in preventing BPF developing after extrapleural pneumonectomy (EPP) and external radiation therapy in malignant pleural mesothelioma (MPM). Methods: Between May 1999 and Dec. 2008, 37 patients with MPM were operated upon by EPP using LDMF prophylactically to reinforce the bronchial stump, and then received external radiation therapy with or without postoperative chemotherapy. Results: The mean age of all patients was 46.7 (range 26-57) years. Twenty five patients were males and 12 patients were females. Twenty three patients had MPM of the right side and 14 patients had MPM of the left side. The peri-operative mortality was 2.7% and only few flap related postoperative morbidity were reported in the form of minor seroma and subcutaneous surgical emphysema. The median follow up was 17 (range 9-43) months. All cases completed their postoperative external radiation therapy with no reported cases of early or late BPF. Conclusion: Intrathoracic pedicled LDMF transposition is proved to be effective in prevention of BPF developing after EPP and external radiation therapy in MPM and it is advised to be a routine step in EPP in these cases and to use more sophisticated technique of postoperative external beam radiotherapy (3D conformal or IMRT) to minimize this complication.

GOECP/SEOR clinical guidelines on radiotherapy for malignant pleural mesothelioma

Malignant pleural mesothelioma(MPM)is a rare tumor with poor prognosis and rising incidence.Palliative care is common in MPM as radical treatment with curative intent is often not possible due to metastasis or extensive locoregional involvement.Numerous therapeutic advances have been made in recent years,including the use of less aggressive surgical techniques associated with lower morbidity and mortality(e.g.,pleurectomy/decortication),technological advancements in the field of radiotherapy(intensity-modulated radiotherapy,image-guided radiotherapy,stereotactic body radiotherapy,proton therapy),and developments in systemic therapies(chemotherapy and immunotherapy).These improvements have had as yet only a modest effect on local control and survival.Advances in the management of MPM and standardization of care are hampered by the evidence to date,limited by high heterogeneity among studies and small sample sizes.In this clinical guideline prepared by the oncological group for the study of lung cancer of the Spanish Society of Radiation Oncology,we review clinical,histologic,and therapeutic aspects of MPM,with a particular focus on all aspects relating to radiotherapy,including the current evidence base,associations with chemotherapy and surgery,treatment volumes and planning,technological advances,and reradiation.

Multiple bowel intussusceptions from metastatic localized malignant pleural mesothelioma:A case report

Localized malignant pleural mesothelioma (LMPM) is a rare occurrence, and gastrointestinal intra-luminal metastases have not previously been reported. Herein, we report a patient with LMPM who presented with a local recurrence 10 mo after initial en bloc surgical resection. Abdominal computed tomography was performed for intractable, vague abdominal pain with episodic vomiting, which showed a "target sign" over the left lower quadrant. Laparotomy revealed several intra-luminal metastatic tumors in the small intestine and colon and a segmental resection of metastatic lesions was performed. Unfortunately, the patient died of sepsis despite successful surgical intervention. Though local recurrence is more frequent in LMPM, the possibility of distant metastasis should not be ignored in patients with non-specifi c abdominal pain.

Extra-pleural pneumonectomy in the setting of tri-modality therapy for patients with malignant pleural mesothelioma

Although declining in the US due to restrictions of asbestos exposure, malignant pleura/mesothelioma （MPP） remains a very serious thoracic malignancy that is rising in incidence worldwide （1）. Trirnodality therapy with chemotherapy and radiotherapy combined with extrapleural pneumonectomy （EPP） has gained acceptance given the acceptable mortality rate （〈5%） and long term survival reported in patients with epithelial histology, negative margins, and no extrapleural lymph node involvement after trimodalitv treatment （2）.

Integrative decomposition procedure and Kappa statistics set up ATF2 ion binding module in malignant pleural mesothelioma(MPM)

Activating transcription factor 2(ATF2)is a member of the ATF/cyclic AMP-responsive element bind-ing protein family of transcription factors.However,the information concerning ATF2 ion-mediated DNA binding module and function of ATF2 in malignant pleural mesothelioma(MPM)has never been addressed.In this study,by using GRNInfer and GVedit based on linear pro-gramming and a decomposition procedure,with integrated analysis of the function cluster using Kappa statistics and fuzzy heuristic clustering in MPM,we identified one ATF2 ion-mediated DNA binding module involved in invasive function including ATF2 inhibition to target genes FALZ,C20orf31,NME2,PLOD2,RNF10,and RNASEH1,upstream RNF10 and PLOD2 activation to ATF2,upstream RNASEH1 and FALZ inhibition to ATF2 from 40 MPM tumors and 5 normal pleural tissues.Remarkably,our results showed that the predominant effect of ATF2 occupancy is to suppress the activation of target genes on MPM.Importantly,the ATF2 ion-mediated DNA binding module reflects‘mutual’positive and negative feedback regulation mechanism of ATF2 with up-and down-stream genes.It may be useful for developing novel prognostic markers and therapeutic targets in MPM.

The Role of Thymidylate Synthase in Pemetrexed-Resistant Malignant Pleural Mesothelioma Cells

We established new pemetrexed-resistant cells originating from malignant pleural mesothelioma MSTO-211H cells to clarify the mechanism involved in pemetrexed resistance in malignant pleural mesothelioma. In the pemetrexed-resistant cells, only thymidylate synthase (TYMS) mRNA was overexpressed among other well-known molecular targets and chemosensitivity determinants of pemetrexed, and the role of the TYMS gene was ascertained by artificial regulation induced by specific siRNA. Silencing the TYMS expression partially restored the cytotoxicity of pemetrexed. The resistant cells did not display other gene alterations related to folate metabolism. We conclude that the primary mechanism imparting resistance to these cells is specific up-regulation of TYMS function. Further, the TYMS gene may serve as a useful biomarker for the prediction of pemetrexed chemosensitivity in patients with malignant pleural mesothelioma. We also investigated the efficacy of 1-(3-C-ethynyl-β-D-ribo-pento furanosyl)cytosine (ECyd) in overcoming pemetrexed resistance;this compound is presently undergoing clinical trials in the USA as TAS-106. ECyd had a similar antitumor effect on the resistant cells as that on the parental cells. In the clinical treatment of malignant pleural mesothelioma, ECyd promises to emerge as a novel drug.

Malignant Pleural Mesothelioma in Young People

Background: malignant pleural mesothelioma (MPM) is characterized by long latency period between exposure to asbestos and development of the disease so we hypothesize that MPM in the young has different characteristics. Patients and Methods: This is a retrospective study including all eligible patients with malignant pleural mesothelioma presenting to National Cancer Institute, Cairo University during the period from 2008 to 2013. Patients were divided into two groups: Group 1: patients aged ≤45 years. Group 2: Patients aged >45 years. Both groups were assessed regarding different clinicpathological features. Primary Objectives: comparison of different epidemiological features of both groups. Secondary Objectives: assessment of clinical response (CR), progression free survival (PFS) and overall survival (OS) in both groups. Results: 102 Patients were included with median follow up of 14.4 months. Group (1) included 35 patients with mean age 40 ± 3.65 years (31 to 45 years). Group (2) included 67 patients with mean age of 58.6 ± 8.5 years (46 to 87 years). 68% of group (1) came from endemic areas which is significantly higher than group (2): (35.8%), p = 0.02. History of Asbestos exposure was highly significantly different between the 2 groups, 77.1% in group (1) versus 38.8% in group (2), p < 0.001. Other factors showed no significant differences between the two groups. Overall clinical response (CR + PR) was 20% in group (1) versus 17.9% in group (2). P = 0.7. There was a trend towards longer median PFS in young patients, (19.8 ± 8.4 versus 6.9 ± 1.4 months). p = 0.09. The median OS of young patients is significantly longer (20.6 ± 6.3 months) than older patients (11.4 ± 3.6). p = 0.05. Conclusions: Mesothelioma in the young is more sensitive to asbestos exposure, has better OS and likely a different disease entity which needs further studies to understand its underlying biological features.

mprovement of Malignant Pleural Mesothelioma Prognosis： Early Diagnosis and Multimodality Treatment

Malignant pleural mesothelioma （MPM） is the most common primary malignancy of the pleura. The occurrence of malignant mesothelioma is typically related to exposure to mineral fibers such as asbestos and erionite.Reports suggest that genetic factors may also play a role in MPM.141 Moreover, latency periods that are the period of time between the first exposure to asbestos and a disease diagnosis range from 20 to 50 years. The mortality burden from asbestos-related diseases （ARD） is heavy andARD accounts for 92,250 deaths per year globally. To improve survival of MPM patients, effective strategy of early diagnosis and effective treatment strategies are highly needed.

Cancer-directed surgery in malignant pleural mesothelioma: extrapleural pneumonectomy and pleurectomy/decortication

Malignant pleural mesothelioma(MPM)is a primary solid malignancy related to inhalational asbestos exposure.Despite advances in therapy,MPM remains challenging to treat with a post-treatment survival of only 15%at 5-year.In recent years,extra-pleural pneumonectomy has decreased in popularity due to a high morbidity rate and mortality compared to pleurectomy/decortication and other therapeutic alternatives.In this review,we will discuss both procedures,outcomes,ongoing studies,and the roles of surgery in the future treatment of this disease.

Tumour suppressor microRNAs contribute to drug resistance in malignant pleural mesothelioma by targeting anti-apoptotic pathways

Aim:Aberrant microRNA expression is a common event in cancer drug resistance,however its involvement in malignant pleural mesothelioma(MPM)drug resistance is largely unexplored.We aimed to investigate the contribution of microRNAs to the resistance to drugs commonly used in the treatment of MPM.Methods:Drug resistant MPM cell lines were generated by treatment with cisplatin,gemcitabine or vinorelbine.Expression of microRNAs was quantified using RT-qPCR.Apoptosis and drug sensitivity assays were carried out following transfection with microRNA mimics or BCL2 siRNAs combined with drugs.Results:Expression of miR-15a,miR-16 and miR-34a was downregulated in MPM cells with acquired drug resistance.Transfection with miR-15a or miR-16 mimics reversed the resistance to cisplatin,gemcitabine or vinorelbine,whereas miR-34a reversed cisplatin and vinorelbine resistance only.Similarly,in parental cell lines,miR-15a or miR-16 mimics sensitised cells to all drugs,whereas miR-34a increased response to cisplatin and vinorelbine.Increased microRNA expression increased drug-induced apoptosis and caused BCL2 mRNA and protein reduction.RNAi-mediated knockdown of BCL2 partly recapitulated the increase in drug sensitivity in cisplatin and vinorelbine treated cells.Conclusion:Drug-resistant MPM cell lines exhibited reduced expression of tumour suppressor microRNAs.Increasing tumour suppressor of microRNA expression sensitised both drug resistant and parental cell lines to chemotherapeutic agents,in part through targeting of BCL2.Taken together,these data suggest that miR-15a,miR-16 and miR-34a are involved in the acquired and intrinsic drug resistance phenotype of MPM cells.

Sarcomatoid malignant pleural mesothelioma confirmed by full-thickness biopsy

Diffuse malignant pleural mesothelioma （DMPM） is a rare thoracic malignancy, but its incidence isdramatically increasing worldwide as a result ot widespread use of asbestos. The World Health Organization classifies DMPM into three types： epithelioid, sarcomatoid, and biphasic types. DMPM remains suffering poor prognosis and the diagnosis should always be based on adequate, representative tissue samples. There still remains a considerable number of patients with DMPM who are misdiagnosed after a complete investigation including thoracoscopic biopsies.

Promising therapeutic potential of tumor suppressor microRNAs for malignant pleural mesothelioma

Malignant pleural mesothelioma(MPM)is an aggressive and recalcitrant surface neoplasm that defies current multimodality treatments.MicroRNAs(miRNAs)are small noncoding RNAs that epigenetically regulate multiple gene networks and cellular processes.In cancer,miRNA dysregulation is associated with tumorigenesis,with tumor suppressor miRNAs underexpressed or lost,while oncogenic miRNAs are overexpressed.Consequently,miRNAs have emerged as potential therapeutic candidates.Because loss of tumor suppressors predominates the pathophysiology of MPM,re-expressing tumor suppressor miRNAs could be an effective therapeutic strategy.This review highlights the most promising MPM-specific tumor suppressor miRNAs that could be developed into novel therapeutics,the supporting data,and what is known about their molecular mechanism(s).

Immunotherapy in malignant pleural mesothelioma:a long story ended in success

Malignant pleural mesothelioma(MPM)is an aggressive and rare disease,mainly due to asbestos exposure,characterized by a poor prognosis.For almost two decades,platinum-based chemotherapy has been the only approved therapeutic regimen for first-line MPM,with an overall survival of 12 months.In the last years,the therapeutic scenario of different tumor types,including MPM,has dramatically changed due to immune checkpoint inhibition.The promising results of this approach have promoted new efforts into clinical research,and many trials investigating novel therapeutic combinations are currently ongoing.The aim of the present review is to provide a comprehensive overview of the most promising immunotherapeutic-based strategies currently under investigation for advanced MPM.

Treatment of unresectable malignant pleural mesothelioma in 2021: emerging standards in immunotherapy

Patients with unresectable malignant pleural mesothelioma(MPM)have historically poor outcomes and treatment,and their treatments have been limited to palliative chemotherapy.Recent efforts to improve prognosis for these patients by adding angiogenesis inhibitors to chemotherapy led to significant benefits.However,the emergence of immunotherapy combinations for the front-line treatment has upended the standard of care and has led to the first new FDA approvals for the treatment of MPM in nearly two decades.This review aims to cover the main clinical trials in unresectable MPM with VEGF inhibitors and immunotherapy which have led to paradigm shifts in current practice.Ongoing clinical trials exploring the combination of chemo and immunotherapies show a great deal of promise,and continued support for ambitious,large-scale well-designed trials remain vital for defining the future outcomes of patients diagnosed with MPM.

恶性胸膜间皮瘤细胞培养条件及CDKN2B对癌细胞的作用

目的探讨不同培养条件(RPMI-1640、DMEM和DMEM/F12培养液)对人恶性胸膜间皮瘤(malignant pleural mesothelioma,MPM)组织中分离的MPM细胞传代的影响以及细胞周期蛋白依赖性激酶抑制剂2B(cyclin dependent kinase inhibitor 2B,CDKN2B)对MPM细胞增殖、侵袭和凋亡的作用。方法从MPM组织中分离细胞分别用RPMI-1640、DMEM和DMEM/F12培养液培养。CCK-8检测细胞增殖,细胞核及染色体利用瑞氏-吉姆萨染色观察,免疫荧光实验检测MPM标志物Calretinin、CD141、CK5、EMA和WT-1荧光强度。RT-qPCR和Western blot分别检测CDKN2B的mRNA和蛋白表达能力。Transwell检测细胞侵袭能力,流式细胞术检测细胞凋亡率。结果建立的MPM细胞在RPMI-1640、DMEM和DMEM/F12培养液中传至第10代仍具有较好的活力,且MPM标志物Calretinin、CD141、CK5、EMA和WT-1在细胞中均表达,MPM细胞在RPMI-1640培养液中活力较为稳定。CDKN2B在MPM细胞中低表达(P<0.05),过表达CDKN2B显著抑制MPM细胞的增殖(P<0.05)、侵袭(P<0.05)和上皮间质转化(P<0.01),促进细胞凋亡(P<0.01)。结论建立的MPM细胞可在RPMI-1640培养液中稳定传代,CDKN2B可作为MPM诊断和治疗的潜在靶标。

恶性胸膜间皮瘤靶向治疗的研究进展

恶性胸膜间皮瘤(malignant pleural mesothelioma, MPM)是侵袭性极强的罕见胸膜表面恶性肿瘤,危险因素包括吸入石棉、遗传因素、基因突变等。现有的化疗、抗血管生成治疗、免疫治疗的效果均不佳,患者的生存期极短。亟需寻找治疗MPM的潜在靶点,目前发现有基因突变靶点如BRCA1相关蛋白1(BRCA associated protein1, BAP1)和细胞周期蛋白依赖性激酶抑制剂2A(cyclin-dependent kinase 2A, CDKN2A)等;表观遗传靶点如组蛋白赖氨酸去甲基酶4A[lysine (K)-specific demethylase 4A, KDM4A]和赖氨酸特异性去甲基酶1(lysine-specific demethylase1, LSD1)等;信号蛋白靶点如葡萄糖调节蛋白78(glucose-regulated protein 78, GRP78)及信号转导和转录激活因子3(signal transducer and activator of transcription 3, STAT3)等。迄今为止,可查询的临床试验有组蛋白甲基转移酶抑制剂Tazemetostat、多聚ADP-核糖聚合酶[poly (ADP-ribose) polymerase, PARP]抑制剂Rucaparib和细胞周期蛋白依赖性激酶4/6(cyclin-dependent kinases 4 and 6, CDK4/6)抑制剂Abemaciclib的II期临床试验,以及靶向间皮素的嵌合抗原受体T细胞免疫疗法(chimeric antigen receptor T-cell immunotherapy, CAR-T)细胞胸腔注射、TEA结构域家族成员(TEA domain family member, TEAD)抑制剂VT3989和IK-930的I期临床试验,显示出一定的临床疗效。