Malignant Peritoneal Mesothelioma Research Articles

Abstract C069: Unraveling the complexity of malignant peritoneal mesothelioma: A comprehensive case study of diagnosis, clinical features, and therapeutic challenges in a 75-year-old male

Abstract Introduction: Malignant Peritoneal Mesothelioma (MPM) is a rare and aggressive intra-abdominal neoplasm originating from mesothelial cells. Although asbestos exposure is a known risk factor, MPM's molecular pathogenesis differs from its pleural counterpart. Case Presentation: A 75-year-old male, with a past medical history of recently diagnosed mesothelioma, presented to the emergency department for a two-week progression of abdominal distension, early satiety, and dyspnea aggravated by activity. One year prior, he initiated medical evaluation for fluid retention and abdominal distension. A recent omental biopsy confirmed the diagnosis of mesothelioma, prompting the initiation of chemotherapy every three weeks. Despite paracentesis performed monthly, the patient experienced worsening shortness of breath and early satiety post-chemotherapy. Discussion: Malignant Peritoneal Mesothelioma poses a diagnostic challenge due to the absence of specific signs or symptoms. Common manifestations include abdominal distension, pain, early satiety, weight loss, dyspnea, chest pain, and fatigue. Rare symptoms encompass new-onset hernia, fever of unknown origin, night sweats, or incidental findings during physical examinations or laparoscopy. Delays in presentation and diagnosis contribute to the advanced stage at diagnosis, with most cases having already spread throughout the abdominal cavity. Three distinct presentations of MPM include the Dry Painful Type, characterized by abdominal pain with minimal ascites; the Wet Type, presenting with abdominal distension and ascites; and the Mixed Type, combining abdominal pain and distension. Paraneoplastic phenomena, such as fever, thrombocytosis, malignancy-related thrombosis, hypoglycemia, hypoalbuminemia, paraneoplastic hepatopathy, and rarely, Coombs-positive Hemolytic anemia, further complicate the clinical picture. Surgical gross and microscopic descriptions of liver biopsies indicated chronic hepatitis with mild portal inflammation, grade 1, and no fibrosis, stage 0. Notably, the omental biopsy confirmed Malignant Mesothelioma of the epithelioid type. Immunohistochemical stains supported the diagnosis, revealing positivity for CK AE1/AE3, calretinin, WT1, CK7 (focally), and GATA3 (focally), while testing negative for BAP1, CDX2, chromogranin, CK20, hepatocyte antigen, PAX8, PSA, synaptophysin, and TTF1. Due to the rarity of MPM, no standardized treatment protocols exist. Cytoreductive surgery (CRS) and hyperthermic intraoperative peritoneal perfusion with chemotherapy (HIPEC) are recommended for selected patients without extraperitoneal disease spread, possessing a good performance status and potential for complete surgical cytoreduction. Systemic chemotherapy, particularly pemetrexed-based regimens, is advocated for patients ineligible for CRS/HIPEC. Conclusion: MPM's aggressive nature poses diagnostic and therapeutic challenges. The scarcity of standardized guidelines emphasizes the importance of ongoing research to enhance understanding, improve diagnostics, and develop targeted therapies Citation Format: Aliya M Khan, Mehmet Hepgur, Aryama Sharma. Unraveling the complexity of malignant peritoneal mesothelioma: A comprehensive case study of diagnosis, clinical features, and therapeutic challenges in a 75-year-old male [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C069.

Perfusion Strategies for Cytoreductive Surgery With Heated Intraperitoneal Chemotherapy for Malignant Peritoneal Mesothelioma.

Cytoreductive surgery (CRS) with heated intraoperative intraperitoneal chemotherapy (HIPEC) has been shown to improve survival for patients with malignant peritoneal mesothelioma (MPM). Presently, there is no standardized HIPEC protocol with respect to chemotherapeutic agent, dose, administration temperature, or duration and limited literature comparing outcomes in different regimens. In this study, we analyze common practices and outcomes of published HIPEC regimens to gain insight into current practice to inform future directions of study. We conducted a literature search for investigational studies of CRS and HIPEC for MPM treatment in adults and identified 35 such articles. These studies were analyzed for institution type and location, drug regimens, perfusion temperatures and time, and study outcomes including median survival, complication rates, and perioperative mortality rates. On review, there is significant heterogeneity in HIPEC regimens and outcome reporting metrics, suggesting a need for multi-institutional standardized study protocols to better determine the safest and most efficacious treatment regimen.

Effect of postoperative normothermic intraperitoneal chemotherapy on the prognosis of MPM patients receiving CRS+HIPEC: A single-center case-control study

BackgroundThe comprehensive treatment strategy, mainly cytoreductive surgery (CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC), combined with systemic and intraperitoneal chemotherapy, is the standard treatment for malignant peritoneal mesothelioma (MPM), which can significantly prolong the survival of patients. The aim of this study is to investigate the clinical significance of postoperative normothermic intraperitoneal chemotherapy (NIPEC) in MPM patients. MethodsData of 152 MPM patients who underwent CRS + HIPEC and postoperative intravenous chemotherapy were retrospectively analyzed. Patients were divided into the Non-NIPEC group and the NIPEC group according to whether they received NIPEC after surgery. The baseline characteristics of the two groups were compared, and the survival outcome was analyzed in subgroups according to completeness of cytoreduction (CC) score. Multivariate survival analysis was used to determine the independent prognostic factors. ResultsIn CC 0–1 and CC 2–3 subgroups, there was no significant difference in baseline characteristics between Non-NIPEC and NIPEC groups. Survival analysis showed that for CC 0–1 patients, there was no significant difference in overall survival (OS) between Non-NIPEC and NIPEC groups (P = 0.503). However, for CC 2–3 patients, the median OS of the NIPEC group was significantly longer than that of the Non-NIPEC group (24.5 vs. 10.3 months, P = 0.005). Pathological type, preoperative thrombosis and postoperative NIPEC (HR = 0.423, 95%CI: 0.228–0.786, P = 0.006) were independent prognostic factors for CC 2–3 patients. ConclusionsFor MPM patients receiving CRS + HIPEC, postoperative intraperitoneal combined with intravenous chemotherapy may improve the survival of CC 2–3 patients, but CC 0–1 patients do not seem to derive the same benefit.

Drug sensitivity tumor cell clusters in malignant peritoneal mesothelioma.

To explore the most effective adjuvant chemotherapy regimen for malignant peritoneal mesothelioma (MPM) through patient derived tumor-like cell clusters (PTC) drug sensitivity test. PTC were cultured in vitro with intraoperative specimens, and drug sensitivity test was performed to calculate the most effective chemotherapy regimen for MPM. The patients were divided into conventional and individualized chemotherapy group according to whether they received PTC drug testing. Univariate and multivariate analyses were conducted to identify independent prognostic factors. Among 186 MPM patients included, 63 underwent PTC culture and drug sensitivity test. The results showed that the most effective chemotherapy regimen was oxaliplatin + gemcitabine. After propensity score matching, a total of 64 patients were enrolled in the following study, including 32 patients receiving individualized chemotherapy guided by PTC drug results as group 1 and 32 patients receiving conventional chemotherapy as group 2. Survival analysis showed that the median OS of group 1 was not reached, significantly longer than that of group 2 (23.5 months) (p < 0.05). Compared with conventional chemotherapy, individualized chemotherapy guided by PTC drug sensitivity tests can prolong patient survival, and oxaliplatin + gemcitabine + apatinib could be the optimal adjuvant treatment regimen for MPM.

STK11 (LKB1) immunohistochemistry is a sensitive and specific marker for STK11 adnexal tumours.

ST11 adnexal tumour is a rare, recently described malignant neoplasm that is associated with Peutz-Jeghers syndrome. It predominantly originates from the para-adnexal soft tissues and often shows secondary involvement of the fallopian tube and ovary. STK11 adnexal tumours have a broad differential diagnosis due to their variable morphology and non-specific immunoprofile, and diagnostic confirmation currently requires sequencing to identify an STK11 mutation. We investigate the diagnostic utility of STK11 (LKB1) immunohistochemistry (IHC) in a cohort of STK11 adnexal tumours and morphological mimics. IHC for STK11 was performed on 122 tumours, including 17 STK11 adnexal tumours and 105 morphological mimics (10 female adnexal tumours of Wolffian origin, 22 adult granulosa cell tumours, 10 juvenile granulosa cell tumours, four Sertoli-Leydig cell tumours, two Leydig cell tumours, one Sertoli cell tumour, one steroid cell tumour, four extra-ovarian sex cord-stromal tumours, 16 ovarian endometrioid carcinomas, eight tubo-ovarian high-grade serous carcinomas, five ovarian mesonephric-like adenocarcinomas, 14 ovarian carcinosarcomas, five peritoneal malignant mesotheliomas, two pelvic plexiform leiomyomata and one ovarian solid pseudopapillary tumour). All STK11 adnexal tumours showed complete loss of cytoplasmic staining for STK11. All other tumour types showed retained cytoplasmic staining, except for one endometrioid carcinoma with mucinous differentiation which showed complete loss of STK11 expression and a high-grade serous carcinoma with subclonal loss. STK11 is a highly sensitive and specific immunohistochemical marker for distinguishing STK11 adnexal tumour from its histological mimics, and can obviate the need for confirmatory molecular studies in the appropriate morphological context.

Development in the Study of Natural Killer Cells for Malignant Peritoneal Mesothelioma Treatment.

Malignant peritoneal mesothelioma (MPeM) is a rare primary malignant tumor originating from peritoneal mesothelial cells. Insufficient specificity of the symptoms and their frequent reappearance following surgery make it challenging to diagnose, creating a need for more efficient treatment options. Natural killer cells (NK cells) are part of the innate immune system and are classified as lymphoid cells. Under the regulation of activating and inhibiting receptors, NK cells secrete various cytokines to exert cytotoxic effects and participate in antiforeign body, antiviral, and antitumor activities. This review provides a comprehensive summary of the specific alterations observed in NK cells following MPeM treatment, including changes in cell number, subpopulation distribution, active receptors, and cytotoxicity. In addition, we summarize the impact of various therapeutic interventions, such as chemotherapy, immunotherapy, and targeted therapy, on NK cell function post-MPeM treatment.

Spatial landscape of malignant pleural and peritoneal mesothelioma tumor immune microenvironment.

Immunotherapies have demonstrated limited clinical efficacy in malignant mesothelioma treatment. We conducted multiplex immunofluorescence (mIF) analyses on tissue microarrays (n=3) from malignant peritoneal (MPeM, n=25) and pleural (MPM, n=88) mesothelioma patients. Our study aimed to elucidate spatial distributions of key immune cell populations and their association with LAG3, BAP1, NF2, and MTAP, with MTAP serving as a CDKN2A/B surrogate marker. Additionally, we examined the relationship between the spatial distribution of major immune cell types with MM patient prognosis and clinical characteristics. We observed a higher degree of interaction between immune cells and tumor cells in MPM compared to MPeM. Notably, within MPM tumors, we detected a significantly increased interaction between tumor cells and CD8+ T cells in tumors with low BAP1 expression compared to those with high BAP1 expression. To support the broader research community, we have developed The Human Spatial Atlas of Malignant Mesothelioma (https://mesotheliomaspatialatlas.streamlit.app/), containing mIF and hematoxylin and eosin (H&E) images.

Research progress of malignant peritoneal mesothelioma with paraneoplastic syndrome: A review.

Malignant peritoneal mesothelioma (MPM) is a rare and invasive tumor, and some patients will develop paraneoplastic syndrome (PS) during the course of the disease. This review summarizes PS associated with MPM, focusing on the clinical characteristics and treatment progress in hematological, endocrine, rheumatic, neurological, urinary, and other systems to decrease missed diagnosis and misdiagnosis, help early diagnosis and prompt treatment, and provide guidance for the clinical decision-making of this kind of patients.

Immune checkpoint inhibitors in advanced malignant peritoneal mesothelioma: Clinical insights, immunopathologic profiling, and prognostic implications from a single-center study.

e14665 Background: Malignant peritoneal mesothelioma (MPM) is a rare malignancy of the peritoneum. In patients with advanced disease, therapeutic options are limited, and prognosis is usually poor. While the role of immune-checkpoint inhibitors (ICI) in MPM is evolving, clinical data is scarce and there are currently no biomarkers to predict response to ICI therapy in this population. Methods: Patients treated at the Sheba Medical Center between 2016-2022 have been examined with the aim of delineating the clinical and immunopathologic characteristics of MPM, including programmed-death ligand-1 (PDL-1) status. Results: Forty-two patients with MPM were treated at Sheba during the study period. Eight patients (19%) have received immunotherapy as a single treatment in our cohort, all as ≥2 line of treatment. Of these patients, 3 patients (37.5%) had complete response (CR) or partial response (PR) as their best response, 3 patients (37.5%) had stable disease (SD), and 2 patients (25%) had progressive disease. Median overall survival (OS) among responding patients (CR/PR) and patients with clinical benefit (CR/PR/SD) were 6.8 years and 5.2 years, respectively, noticeably higher than the median OS for MPM (2.5 years). PDL-1 status was available for 23 patients: 17/23 (74%) had negative PDL-1 status and 6/23 (26%) had positive PDL-1 status. No correlation was observed in PDL-1 status among patients experiencing clinical benefit from treatment with ICIs. Conclusions: ICI therapy could be considered as a reasonable option for second-line therapy and beyond for MPM, with selected patients who may substantially benefit from these treatments. PDL-1 status did not correlate with treatment benefit, which highlights the limitation of this biomarker as a predictor of response in MPM patients.

Disease monitoring using plasma-based circulating tumor DNA (ctDNA) assays in rare malignancies.

e15046 Background: ctDNA assays can be used to assess molecular residual disease, and the value of ctDNA monitoring in disease surveillance and treatment response assessment has been demonstrated in colon, breast, lung, and bladder cancers. However, the data of ctDNA in rare cancers has been lacking. We conducted this retrospective study to investigate the potential roles of ctDNA monitoring in rare tumors in both surveillance and response evaluation. Methods: ctDNA assay results of 12 patients (pts) with rare cancers including adrenocortical carcinoma (ACC) (4 pts), salivary gland cancers (3 pts), pleural or peritoneal malignant mesothelioma (4 pts), and anaplastic thyroid cancer (ATC) (1pt) undergoing treatment or surveillance in 2023 at Mayo Clinic Florida were analyzed. The trends of ctDNA levels were correlated with radiographic images findings. Results: Among the 12 patients, ctDNA was detected in at least one time point in 9 (75%) pts, including 1 (100%) ATC pt, 2 (66%) salivary gland pts, 3 (75%) malignant mesothelioma pts, and 3 (75%) ACC pts. Among these 9 pts, 5 pts had ctDNA collected at more than one timepoints, and the trends of ctDNA levels were consistent with image findings in all 5 pts. Among these 5 pts, one pt received definitive surgery for ACC with clearance of ctDNA after the surgery and one salivary gland cancer pt was undergoing surveillance and later developed disease progression. The other 3 pts were undergoing palliative systemic therapy and had responded to treatments. Conclusions: ctDNA was detectable in majority of the patients with rare malignancies reviewed in this study, including ACC, ATC, pleural or peritoneal malignant mesothelioma, and salivary gland cancers. Further study is warranted to investigate the role of ctDNA monitoring in surveillance and treatment response evaluation in rare malignancies.

Analysis of Treatment Strategies and Outcomes in Malignant Peritoneal Mesothelioma: Insights From a Multi-Center Study

BackgroundThis study aimed to evaluate the demographic,” clinicopathologic, and prognostic characteristics of malignant peritoneal mesothelioma (MPeM), as well as the treatment options for the rare and heterogeneous MPeM population.MethodsA retrospective multi-center observational cohort study was conducted to evaluate patients with MPeM. Due to the heterogeneity of the study population, the study divided them into two main groups in terms of treatments, follow-up periods, and prognostic features. The first group comprised the patients who underwent cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC), and the second group included the patients with metastatic disease for whom curative intent surgery was not possible. The patients’ diagnostic procedures and treatments were identified from medical records. Patients older than 18 years old were included in the study regardless of asbestos exposure. Well-differentiated papillary and multicystic mesothelioma histologic types were not included in the study.ResultsThe study evaluated 118 patients from five centers. Survival times, prognosis, and treatment responses were analyzed in both groups. The study showed that CRS-HIPEC was associated with longer overall survival (OS) and progression-free survival (PFS). Perioperative therapy was evaluated in subgroup analyses of this population and shown to provide survival benefits. The patients treated with chemotherapy (metastatic and medically inoperable patients and those for whom complete cytoreduction was not achievable) had a poorer prognosis than the surgery group. The study showed that life expectancy decreased significantly for the patients not suitable to undergo surgery for any reason.ConclusionsAccording to data from experienced centers, CRS-HIPEC is a treatment option recognized as effective, cost-effective, and safe, with better OS and PFS , as well as low morbidity and mortality rates similar to those in the literature. In addition, the platinum-pemetrexed combination continues to be an effective and acceptable treatment option for metastatic patients, those who are medically inoperable, and those for whom complete or near-complete cytoreduction is not achievable.

Malignant peritoneal mesothelioma interactome with 417 novel protein–protein interactions

BackgroundMalignant peritoneal mesothelioma (MPeM) is an aggressive cancer affecting the abdominal peritoneal lining and intra-abdominal organs, with a median survival of ~2.5 years.MethodsWe constructed the protein interactome of 59 MPeM-associated genes with previously known protein-protein interactions (PPIs) as well as novel PPIs predicted using our previously developed HiPPIP computational model and analysed it for transcriptomic and functional associations and for repurposable drugs.ResultsThe MPeM interactome had over 400 computationally predicted PPIs and 4700 known PPIs. Transcriptomic evidence validated 75.6% of the genes in the interactome and 65% of the novel interactors. Some genes had tissue-specific expression in extramedullary hematopoietic sites and the expression of some genes could be correlated with unfavourable prognoses in various cancers. 39 out of 152 drugs that target the proteins in the interactome were identified as potentially repurposable for MPeM, with 29 having evidence from prior clinical trials, animal models or cell lines for effectiveness against peritoneal and pleural mesothelioma and primary peritoneal cancer. Functional modules related to chromosomal segregation, transcriptional dysregulation, IL-6 production and hematopoiesis were identified from the interactome. The MPeM interactome overlapped significantly with the malignant pleural mesothelioma interactome, revealing shared molecular pathways.ConclusionsOur findings demonstrate the utility of the interactome in uncovering biological associations and in generating clinically translatable results.

Nursing of a patient with malignant peritoneal mesothelioma

Nursing of a patient with malignant peritoneal mesothelioma

Abstract 4642: Fatty acid synthase as a novel prognostic biomarker and a potential therapeutic target in diffuse malignant peritoneal mesothelioma

Abstract Diffuse malignant peritoneal mesothelioma (DMPM) is a rare and locally aggressive tumor with a dismal prognosis. The availability of new therapies and biomarkers for patients’ selection is still an urgent need. Altered lipid metabolism, which has been reported in several tumors, has not yet been studied in DMPM. By comparatively analyzing gene expression profiles of tumors form relapsed (n=18) and non-relapsed (n=18) DMPM patients, we initially found that fatty acid synthase (FASN) was up-modulated in relapsed tumors, with a significant linear correlation between FASN expression and shorter patient relapse-free survival (RFS), suggesting a potential role of FASN in DMPM progression. The prognostic significance of FASN was further assessed in a cohort of 80 DMPM patients who underwent cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy. Our results indicated that high FASN staining was significantly associated with reduced RFS (hazard ration (HR): 1.930; p=0.014) and Overall Survival (OS) (HR: 1.854; p=0.032) as assessed by immunohistochemistry in tissues microarray samples. The prognostic value of FASN, along with Ki67 staining and patient age, was also maintained in multivariate analysis in terms of both RFS (HR: 2.240; p=0.007) and OS (HR: 2.246; p=0.014). To validate FASN as a therapeutic target, we investigated the cytotoxic effects of non-selective (orlistat) and selective (cerulenin and C75) FASN inhibitors on patient-derived DMPM cell lines, both as single agents and in combination with selinexor -a selective inhibitor of the exportin chromosome maintenance protein. FASN pharmacological inhibition in DMPM cells resulted in a significant reduction of cell proliferation, especially upon C75 exposure. In combination experiments, we observed a synergistic activity of FASN inhibitors and selinexor, as determined by Chou and Talalay method. Through western blotting and flow cytometry analysis, we gained further insight into the mechanisms by which FASN inhibitors and selinexor synergize to reduce DMPM cell proliferation. Compared to single agents, the combined treatments resulted in increased apoptosis response and cell cycle impairment, as indicated by caspase-dependent apoptosis activation and cell accumulation in the G2-phase. Overall, our results support the relevance of FASN as a prognostic biomarker for DMPM patients and underscore its potential as a novel therapeutic target. Citation Format: Valentina Doldi, Silvia Martini, Chiara Maura Ciniselli, Alessia Beretta, Marcello Deraco, Shigeki Kusamura, Dario Baratti, Paolo Gandellini, Paolo Verderio, Nadia Zaffaroni. Fatty acid synthase as a novel prognostic biomarker and a potential therapeutic target in diffuse malignant peritoneal 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 4642.

Abstract 2995: The ectopic expression of miR-380-5p interferes with the aggressive traits of diffuse malignant peritoneal mesothelima cells

Abstract Telomerase activity (TA) and the alternative lengthening of telomere (ALT) pathway are two telomere maintenance mechanisms (TMM) yet identified in human cancers. Although the activation of either TMM seems to be equivalent in supporting tumor cell immortalization (a hallmark of cancer), the contribution of TA and ALT to tumor progression and aggressiveness may be different. Mounting evidence suggests that cancer cell aggressiveness could be associated with a TA↔ALT shift that would allow the acquisition of distinct aggressive traits. We previously showed that an ALT-like phenotype emerged in diffuse malignant peritoneal mesothelioma (DMPM) cells upon miR-380-5p-dependent inhibition of TA (Cimino-Reale G, et al. J Hematol Oncol. 2017). To analyze the transcriptomic changes associated with the emergence of such a phenotype, gene expression profiling was carried out. Results showed that 3331 genes were differentially expressed (FDR&amp;lt;0.05, adjusted for multiple hypothesis testing) in miR-380-5p- vs. preNeg-transfected DMPM cells, out of which 1673 genes were up-regulated and 1658 genes down-regulated. To get biological meaning about the molecular events occurring upon miR-380-5p reconstitution, Gene Set Enrichment Analysis was performed. Results showed a positive enrichment of 188 gene sets, restricted for an FDR &amp;lt; 0.05, out of which signatures related to DNA replication, DNA recombination and telomere maintenance via recombination were present. Conversely, only 1 gene set (GO: positive regulation of blood vessel endothelial cell migration) was negatively enriched at significant level. Notably, among the leading edge genes, PTGS2, which encodes for cyclooxygenase-2 (COX-2) and represents a predicted target of miR-380-5p (miRWalk), was the most significantly down-regulated gene (FDR&amp;lt; 0.000001; log(fold-change): -2.15). Notably, a complete abrogation of PTGS2 expression levels and COX-2 protein amounts was observed in miR-380-5p- compared to preNeg-transfected cells upon validation by qRT-PCR and western blotting, respectively. This evidence was paralleled by reduced amounts of phospho-FAK (focal adhesion kinase) and impaired migrating/invading capabilities of cells ectopically expressing miR-380-5p. Moreover, a reduction of Vimentin and a slight increase in P-Cadherin protein levels were also observed in cells ectopically expressing miR-380-5p, likely indicating the occurrence of a reverse-EMT program. Finally, a pronounced increase in the sensitivity to Cisplatin and Doxorubicin was also appreciable in miR-380-5p- vs. preNeg-transfected cells, suggesting that miRNA-mediated induction of a reverse-EMT may, at least in part, contribute to improve the response of DMPM cells to chemotherapeutic drugs. Citation Format: Stefano Percio, Lorenzo Di Pietro, Eisa Naghshineh, Marcello Deraco, Nadia Zaffaroni, Marco Folini. The ectopic expression of miR-380-5p interferes with the aggressive traits of diffuse malignant peritoneal mesothelima cells [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 2995.

Liver metastatic colonization by invasive cancer cells: a review of potential biomarkers with mitochondrial involvement

The liver, characterized by a unique metabolic and immunosuppressive environment, is also the organ to which invasive malignant cells of many different cancer types most frequently metastasize. The reasons for this organ-specific metastatic process have been investigated for decades. This review first provides an overview of recent breakthroughs in this field, introducing intercellular communication between circulating tumor cells and the heterogeneous cell populations of the liver, and modifications to the extracellular matrix (ECM). Subsequently, to improve the understanding of the molecular mechanisms involved in the metastasis of colorectal cancer to the liver, the second leading cause of cancer-related mortality, the recent literature on this question was analyzed. Among the various parameters involved, the mechanisms behind the activation of hepatic stellate cells, proteins inducing ECM remodeling, specific genomic features of liver metastases, metabolic rewiring, and characteristics of stromal-enriched microenvironments were discussed. To provide more insights into the molecular determinants of liver metastatic colonization, important findings reported on a set of mitochondrial proteins were addressed, the relative abundance of which changed in the liver during the progression stage of an aggressive experimental model of peritoneal malignant mesothelioma in immunocompetent rats. Based on previous studies cross-comparing the liver proteomes from curcumin-treated tumor-bearing rats/untreated tumor-bearing rats/normal rats, data from the literature were reviewed for 25 mitochondrial proteins of interest. Their role in lipid metabolism, heme biosynthesis, the electron transport chain, small molecule transport, mitochondrial dynamics, the tricarboxylic acid cycle, and protection against oxidative stress were analyzed in the context of both cancer and non-malignant liver diseases.

Implementation of a high-resolution, high-contrast magnetic resonance imaging protocol with extended delayed phases for peritoneal mesothelioma.

Imaging of peritoneal malignancies using conventional cross-sectional imaging is challenging, but accurate assessment of peritoneal disease burden could guide better selection for definitive surgery. Here we demonstrate feasibility of high-resolution, high-contrast magnetic resonance imaging (MRI) of peritoneal mesothelioma and explore optimal timing for delayed post-contrast imaging. Prospective data from inpatients with malignant peritoneal mesothelioma (MPM), imaged with a novel MRI protocol, were analyzed. The new sequences augmenting the clinical protocol were (I) pre-contrast coronal high-resolution T2-weighted single-shot fast spin echo (COR hr T2w SSH FSE) of abdomen and pelvis; and (II) post-contrast coronal high-resolution three-dimensional (3D) T1-weighted modified Dixon (COR hr T1w mDIXON) of abdomen, acquired at five delay times, up to 20 min after administration of a double dose of contrast agent. Quantitative analysis of contrast enhancement was performed using linear regression applied to normalized signal in lesion regions of interest (ROIs). Qualitative analysis was performed by three blinded radiologists. MRI exams from 14 participants (age: mean ± standard deviation, 60±12 years; 71% male) were analyzed. The rate of lesion contrast enhancement was strongly correlated with tumor grade (cumulative nuclear score) (r=-0.65, P<0.02), with 'early' delayed phase (12 min post-contrast) and 'late' delayed phase (19 min post-contrast) performing better for higher grade and lower grade tumors, respectively, in agreement with qualitative scoring of image contrast. High-resolution, high-contrast MRI with extended post-contrast imaging is a viable modality for imaging peritoneal mesothelioma. Multiple, extended (up to 20 min post-contrast) delayed phases are necessary for optimal imaging of peritoneal mesothelioma, depending on the grade of disease.

Current clinical practices of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC).

Treatment of peritoneal surface malignancies makes physicians face demanding and new-fangled problems, as there are many uncertain aspects considering the outcomes of affected patients' prognoses. Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) are associated with favorable long-term outcomes in carefully selected patients with peritoneal metastases (PM). We aim to summarize the current results about the initial malignancies and their peritoneal spreads. The current literature has been scrutinized, and studies between 2016 and 2022 were included wherein long-term, progression-free (PFS), and overall survival (OS) data were considered relevant information. Medline, Embase, and Google Scholar have been the main sources. Hereby, we cover all the primer malignancies: gastric, ovarian, and colorectal cancers with peritoneal metastases (PM), malignant peritoneal mesothelioma, and pseudomyxoma peritonei. Examining the advances in the current peer-reviewed literature about the indications of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC), target groups, risk factors, and other influencing elements, we intend to provide a complex state-of-the-art report, establishing the relevant aspects of that emerging treatment method.

A159 MALIGNANT PERITONEAL MESOTHELIOMA: A CASE OF MISTAKEN IDENTITY

Abstract Background In the Western hemisphere, cirrhosis is the most common cause of ascites. One of the least common causes is malignant peritoneal mesothelioma (MPM), which occurs in one in one million cases. MPM can be a diagnostic challenge due to its rarity and features that mimic other causes of ascites. Aims To describe a complex case of MPM, highlighting the diagnostic dilemma stemming from the subtleties of presentation, confounders in ascites diagnostic criteria, and indeterminate testing. Methods We performed a detailed retrospective chart review of a patient who presented with ascites. He was initially given the diagnosis of decompensated cirrhosis and eventually was diagnosed with MPM. He provided his consent for this case report. Results A 37-year-old male presented with progressive ascites and peripheral edema. He had no known exposure to asbestos and consumed 6 standard drinks a day for 2 years; with a prior history of 10 standard drinks a week for over 3 years. His physical examination was unremarkable for cardiac, renal or liver disease. His transthoracic echocardiogram and urinalysis were normal. Abdominal ultrasound showed features of liver cirrhosis with large-volume ascites and a FIB-4 score of 0.34, excluding advanced fibrosis Laboratory investigations including liver tests were normal; with a platelet count of 568 x 109/L. Viral, metabolic and autoimmune liver disease were excluded. A diagnostic paracentesis demonstrated a serum albumin-ascites gradient (SAAG) of 1.3 g/dL. Due to his history of alcohol misuse, imaging findings and high SAAG, he was diagnosed with alcohol-related cirrhosis. His repeat abdominal ultrasound showed multiple liver nodules. Magnetic resonance imaging was done to investigate for hepatocellular carcinoma; revealing diffuse peritoneal carcinomatosis, cirrhosis and large-volume ascites. Investigations to identify the primary malignancy included a computed tomography chest, colonoscopy and EGD. His EGD was the only positive test; showing a 2cm submucosal gastric lesion with normal gastric mucosa pathology. An endoscopic ultrasound (EUS) with fine needle aspiration was then performed; the lesion appearance in keeping with a gastrointestinal stromal tumor (GIST). Pathology favored a diagnosis of poorly differentiated gastric carcinoma. Cytology was positive for malignancy, with the differential being mesothelioma or adenocarcinoma and a repeat SAAG was 1.0 g/dL. Given the discordances, an ultrasound-guided core biopsy was performed of the peritoneal lesions. Pathology revealed features of poorly differentiated epithelioid mesothelioma. A subsequent review of his gastric biopsies revealed similar cells in retrospect were in keeping with mesothelioma. Conclusions The presentation of MPM is not easily distinguishable from other causes of ascites. There must be a high degree of suspicion for malignant ascites in the face of inconsistent clinical and diagnostic findings. Funding Agencies None

Nationwide ten-year treatment evaluation in French centers for 924 patients with diffuse malignant peritoneal mesothelioma

Nationwide ten-year treatment evaluation in French centers for 924 patients with diffuse malignant peritoneal mesothelioma