Identification of a mesothelioma phenotype

Stranger Things: New Roles and Opportunities for Androgen Receptor in Oncology Beyond Prostate Cancer

The androgen receptor (AR) is one of the oldest therapeutic targets in oncology and continues to dominate the treatment landscape for advanced prostate cancer, where nearly all treatment regimens include some form of AR modulation. In this regard, AR remains the central driver of prostate cancer cell biology. Emerging preclinical and clinical data implicate key roles for AR in additional cancer types, thereby expanding the importance of this drug target beyond prostate cancer. In this mini-review, new roles for AR in other cancer types are discussed as well as their potential for treatment with AR-targeted agents. Our understanding of these additional functions for AR in oncology expand this receptor's potential as a therapeutic target and will help guide the development of new treatment approaches.

Frequency of Germline Mutations in Cancer Susceptibility Genes in Malignant Mesothelioma

PURPOSE

The aim of the current study was to determine the prevalence and clinical predictors of germline cancer susceptibility mutations in patients with malignant mesothelioma (MM).

METHODS

We performed targeted capture and next-generation sequencing of 85 cancer susceptibility genes on germline DNA from 198 patients with pleural, peritoneal, and tunica vaginalis MM.

RESULTS

Twenty-four germline mutations were identified in 13 genes in 23 (12%) of 198 patients. BAP1 mutations were the most common (n = 6; 25%). The remaining were in genes involved in DNA damage sensing and repair (n = 14), oxygen sensing (n = 2), endosome trafficking (n = 1), and cell growth (n = 1). Pleural site (odds ratio [OR], 0.23; 95% CI, 0.10 to 0.58; P < .01), asbestos exposure (OR, 0.28; 95% CI, 0.11 to 0.72; P < .01), and older age (OR, 0.95; 95% CI, 0.92 to 0.99; P = .01) were associated with decreased odds of carrying a germline mutation, whereas having a second cancer diagnosis (OR, 3.33; 95% CI, 1.22 to 9.07; P = .02) significantly increased the odds. The odds of carrying a mutation in BAP1 (OR, 1,658; 95% CI, 199 to 76,224; P < .001), BRCA2 (OR, 5; 95% CI, 1.0 to 14.7; P = .03), CDKN2A (OR, 53; 95% CI, 6 to 249; P < .001), TMEM127 (OR, 88; 95% CI, 1.7 to 1,105; P = .01), VHL (OR, 51; 95% CI, 1.1 to 453; P = .02), and WT1 (OR, 20; 95% CI, 0.5 to 135; P = .049) were significantly higher in MM cases than in a noncancer control population. Tumor sequencing identified mutations in a homologous recombination pathway gene in 52% (n = 29 of 54).

CONCLUSION

A significant proportion of patients with MM carry germline mutations in cancer susceptibility genes, especially those with peritoneal MM, minimal asbestos exposure, young age, and a second cancer diagnosis. These data support clinical germline genetic testing for patients with MM and provide a rationale for additional investigation of the homologous recombination pathway in MM.

The genetic susceptibility in the development of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a cancer of the pleural cavity whose main risk factor is exposure to asbestos. However, it has been shown that only a minority of exposed people develops MPM. In fact, the incidence among professionally exposed workers was shown to vary between 0.5% and 18.0%. Various hints suggested that other important cofactors could play a role, in particular the genetic susceptibility. Impressive is the case of Cappadocians families exposed to erionite and affected by an "epidemic" of MPM with about half of the inhabitants dying for the disease. However, no results for a "Cappadocia" gene of susceptibility to MPM have been obtained yet and more studies are needed. Among asbestos-exposed workers, several studies reported familial cases of MPM, suggesting that heredity could be important in the tumor development. However, large studies on familial clusters showed only weak increased risks that could be attributable also to indirect exposures in a contaminated household. Moreover, the risk of developing MPM is increased of a limited extent among people exposed to asbestos with a positive history of familial cancers. A particular is represented by carriers of germline mutations within BAP1 gene. In families and in animal models, mutations within BAP1 are strongly predisposing to develop MPM. However, also other types of cancer (such as uveal melanoma) are present, thus BAP1 mutations are considered as responsible for a hereditary form of a multi-cancer syndrome. In any case, among sporadic MPM, the prevalence of germline BAP1 mutations is negligible. Finally, genetic studies highlighted the presence of low-risk susceptibility alleles, such as those within XRCC3, NAT2 or GSTM1. Two different genome-wide association studies could not find positive associations reaching the genome-wide statistical significance threshold, however, both were concordant in showing a weak signal within the SDK1 gene region. Overall, it could be concluded that, as for other types of sporadic cancers, the susceptibility to develop MPM following asbestos exposure is modulated moderately by the individual genetic background. Further studies on larger series could help in a better characterization of more genes predisposing to MPM, being this tumor a rare disease.

Germline BAP1 Mutational Landscape of Asbestos-Exposed Malignant Mesothelioma Patients with Family History of Cancer

Heritable mutations in the BAP1 tumor suppressor gene predispose individuals to mesothelioma and other cancers. However, a large-scale assessment of germline BAP1 mutation incidence and associated clinical features in mesothelioma patients with a family history of cancer has not been reported. Therefore, we examined the germline BAP1 mutation status of 150 mesothelioma patients with a family history of cancer, 50 asbestos-exposed control individuals with a family history of cancers other than mesothelioma, and 153 asbestos-exposed individuals without familial cancer. No BAP1 alterations were found in control cohorts, but were identified in nine of 150 mesothelioma cases (6%) with a family history of cancer. Alterations among these cases were characterized by both missense and frameshift mutations, and enzymatic activity of BAP1 missense mutants was decreased compared with wild-type BAP1. Furthermore, BAP1 mutation carriers developed mesothelioma at an earlier age that was more often peritoneal than pleural (five of nine) and exhibited improved long-term survival compared to mesothelioma patients without BAP1 mutations. Moreover, many tumors harboring BAP1 germline mutations were associated with BAP1 syndrome, including mesothelioma and ocular/cutaneous melanomas, as well as renal, breast, lung, gastric, and basal cell carcinomas. Collectively, these findings suggest that mesothelioma patients presenting with a family history of cancer should be considered for BAP1 genetic testing to identify those individuals who might benefit from further screening and routine monitoring for the purpose of early detection and intervention.

Germline BAP1 mutation in a family with high incidence of multiple primary cancers and a potential gene-environment interaction

We report a high-risk cancer family with multiple mesotheliomas, cutaneous melanomas, basal cell carcinomas, and meningiomas segregating with a germline nonsense mutation in BAP1 (c.1938T>A; p.Y646X). Notably, most (four of five) mesotheliomas were peritoneal rather than the usually more common pleural form of the disease, and all five mesothelioma patients also developed second or third primary cancers, including two with meningiomas. Another family member developed both cutaneous melanoma and breast cancer. Two family members had basal cell carcinomas, and six others had melanocytic tumors, including four cutaneous melanomas, one uveal melanoma, and one benign melanocytic tumor. The family resides in a subtropical area, and several members had suspected exposure to asbestos either occupationally or in the home. We hypothesize that the concurrence of a genetic predisposing factor and environmental exposure to asbestos and UV irradiation contributed to the high incidence of multiple cancers seen in this family, specifically mesothelioma and various uveal/skin tumors, respectively.

Changing pattern in malignant mesothelioma survival

Survival for mesothelioma has been shown to be poor, with marginal improvement over time. Recent advances in the understanding of pathophysiology and treatment of mesothelioma may impact therapy to improve survival that may not be evident from available clinical trials that are often small and not randomized. Therapies may affect survival differently based on mesothelioma location (pleural vs peritoneal). Data are conflicting regarding the effect of asbestos exposure on mesothelioma location.

OBJECTIVES

We examined survival in a large cohort of mesothelioma subjects analyzed by tumor location and presence and mode of asbestos exposure.

METHODS

Data were analyzed from cases (n = 380) diagnosed with mesothelioma from 1992 to 2012. Cases were either drawn from treatment referrals, independent medical evaluation for medical legal purposes, or volunteers who were diagnosed with mesothelioma. Subjects completed an occupational medical questionnaire, personal interview with the examining physician, and physician review of the medical record.

RESULTS

This study reports better survival for mesothelioma than historical reports. Survival for peritoneal mesothelioma was longer than that for pleural mesothelioma (hazard ratio = 0.36, 95% confidence interval = 0.24-0.54, P < .001) after adjusting for gender and age at diagnosis. Non-occupational cases were more likely to be 1) diagnosed with peritoneal mesothelioma, 2) female, 3) exposed, and 4) diagnosed at a younger age and to have a 5) shorter latency compared to occupational cases (P < .001).

CONCLUSION

Peritoneal mesothelioma was more likely associated with non-occupational exposure, thus emphasizing the importance of exposure history in enhancing early diagnosis and treatment impact.

Malignant mesothelioma in Eastern Asia

Relatively low numbers of malignant mesotheliomas have been reported from Eastern Asia. In order to explore the causes of this fact, the available data on mesothelioma incidence/mortality in five countries (Japan, South Korea, Taiwan, Hong Kong, and Singapore) were reviewed. Data on the industrial histories of the above countries were also examined. Mesothelioma incidence was low, despite a history of high shipbuilding and port activities, in which heavy exposure to asbestos generally has occurred. Underestimation of mesothelioma could partly explain the above discrepancy. Moreover, in some areas a sufficient latency period for mesothelioma development may have not yet elapsed, due to recent industrialization. However, other possibilities have to be considered. The cancer epidemiology in Eastern Asia differs deeply from that seen in Western countries, an indication of differences in etiologic factors of cancer as well as in co-factors. In addition, the oncogenic spectrum of asbestos is wide, and not completely defined. In a very different milieu from that of Western countries, asbestos could preferentially hit targets other than serosal membranes.

Factors that impact susceptibility to fiber-induced health effects

Asbestos and related fibers are associated with a number of adverse health effects, including malignant mesothelioma (MM), an aggressive cancer that generally develops in the surface serosal cells of the pleural, pericardial, and peritoneal cavities. Although approximately 80% of individuals with MM are exposed to asbestos, fewer than 5% of asbestos workers develop MM. In addition to asbestos, other mineralogical, environmental, genetic, and possibly viral factors might contribute to MM susceptibility. Given this complex etiology of MM, understanding susceptibility to MM needs to be a priority for investigators in order to reduce exposure of those most at risk to known environmental carcinogens. In this review, the current body of literature related to fiber-associated disease susceptibility including age, sex, nutrition, genetics, asbestos, and other mineral exposure is addressed with a focus on MM, and critical areas for further study are recommended.

Pathogenesis of malignant pleural mesothelioma and the role of environmental and genetic factors

BACKGROUND

Malignant pleural mesothelioma (MPM) is a rare and aggressive tumor for which no effective therapy exists despite the discovery of many possible molecular and genetic targets. The late stage of MPM diagnosis and the long latency that exist between some exposures and diagnosis have made it difficult to comprehensively evaluate the role of risk factors and their downstream molecular effects.

METHODS

This manuscript is a review of current literature about the pathogenesis of malignant mesothelioma. In this overview, current published studies concerning pathogenesis of malignant mesothelioma are reviewed, with insights into its etiology and pathogenesis. We searched pubmed using the following subjects: mesothelioma, radiation, genetics, pediatric malignant mesothelioma, SV40 virus, and growth factors. We selected 350 valuable articles of which 152 sources were used to complete this review.

CONCLUSION

Many risk factors for MPM development have been recognized including environmental exposures, genetic susceptibility, viral contamination, and radiation. In this review, we discuss the current molecular and genetic contributors to MPM pathogenesis and the risk factors associated with these carcinogenic processes.

Pathogenesis of malignant pleural mesothelioma and the role of environmental and genetic factors

Malignant pleural mesothelioma (MPM) is a rare, aggressive tumor for which no effective therapy exists despite the discovery of many possible molecular and genetic targets. Many risk factors for MPM development have been recognized including environmental exposures, genetic susceptibility, viral contamination, and radiation. However, the late stage of MPM diagnosis and the long latency that exists between some exposures and diagnosis have made it difficult to comprehensively evaluate the role of risk factors and their downstream molecular effects. In this review, we discuss the current molecular and genetic contributors in MPM pathogenesis and the risk factors associated with these carcinogenic processes.

Mesothelioma: you do not have to work for it

Asbestos pollution is a global problem. Asbestos exposure induced mesothelioma does not require an 'occupational' type of exposure. Bystander exposures may result in earlier age of disease onset and more aggressive disease progression as described in the following 3 case reports.