Is 80 the New 70? Octogenarians with Oropharyngeal Squamous Cell Carcinoma

PURPOSE/OBJECTIVE(S)

As the human papilloma virus (HPV) pandemic evolves and life expectancy increases, the number of older adults with oropharyngeal squamous cell carcinoma (OPSCC) continues to increase. However, there is a paucity of data regarding the fastest growing subset of this population: octogenarians (OGs). We sought to understand differences in treatment tolerability and clinical outcomes between septuagenarians (SGs) and OGs with OPSCC.

MATERIALS/METHODS

We identified SGs (age 70-79) and OGs (age 80-89) with OPSCC from a cohort of older adults with nonrecurrent, nonmetastatic head and neck squamous cell carcinoma (HNSCC) treated curatively from 2007-2020. We compared demographics, treatment characteristics and toxicities using Fischer's exact test. Time-to-event outcomes, overall survival (OS), locoregional control (LRC), and disease-specific survival (DSS), were evaluated using the Kaplan-Meier method.

RESULTS

Of 293 patients (age 70-89) with HNSCC, 39% (n = 114) had OPSCC: 93 SGs (median age: 73; interquartile range [IQR]: 71-76), and 21 OGs (median age: 81, IQR: 80-84). The median follow-up for included patients was 2.4 years; 82% were male, 64% white, 48% > 20 pack year smoking history, 37% ECOG 1. Patients had AJCC 8th edition Stage: I (27%); II (33%); III (18%); IV (22%) OPSCC. Treatment consisted of adjuvant radiation (RT) (19%), adjuvant chemoradiation (CRT) (8%), surgery alone (6%), induction/concurrent CRT (27%), concurrent CRT (28%), or RT (12%), with no significant differences in stage or treatment modalities noted between SGs and OGs. Of note, 69% of SGs and 76% of OGs were HPV+. Among 107 patients who received any RT, 24% experienced a treatment interruption (19% of SGs vs. 48% of OGs, p = 0.001) and 2 patients (both HPV- SGs) died on treatment due to unrelated health conditions. Percutaneous endoscopic gastrostomy (PEG) tubes were placed prior to or during treatment in 43% of SGs and 62% of OGs, with OGs more likely to have a PEG placed during treatment (p = 0.025). There was no difference in the prevalence of late (> 6 months) CTCAE grade 2+ dysphagia (36%) or xerostomia (31%) between SGs and OGs. Estimated 3-year LRC, DSS, and OS were not significantly different between SGs (LRC:85%; DSS:87%; OS:76%) and OGs (LRC: 81%; DSS:94%; OS: 55%, p-values: 0.98, 0.42, 0.052, respectively). However, HPV+ disease significantly increased estimated 3-year OS for both SGs (HPV+: 84%; HPV-: 56%, p = 0.0006) and OGs (HPV+: 68%; HPV-: 20%, p = 0.008).

CONCLUSION

In our cohort, OGs had a higher proportion of HPV+ OPSCC, which was associated with improved OS. This finding may provide insight into the latency of the virus. While there were similar amounts of toxicities among SGs and OGs, OGs more frequently underwent PEG tube placement and experienced more treatment interruptions. Given high rates of HPV+ OPSCC in OGs, our findings suggest that de-escalation strategies should be further investigated to improve tolerability and maximize outcomes for this neglected population.

Development and validation of a brief screener for posttraumatic stress disorder risk in emergency medical settings

OBJECTIVE

Predicting risk of posttraumatic stress disorder (PTSD) in the acute care setting is challenging given the pace and acute care demands in the emergency department (ED) and the infeasibility of using time-consuming assessments. Currently, no accurate brief screening for long-term PTSD risk is routinely used in the ED. One instrument widely used in the ED is the 27-item Immediate Stress Reaction Checklist (ISRC). The aim of this study was to develop a short screener using a machine learning approach and to investigate whether accurate PTSD prediction in the ED can be achieved with substantially fewer items than the IRSC.

METHOD

This prospective longitudinal cohort study examined the development and validation of a brief screening instrument in two independent samples, a model development sample (N = 253) and an external validation sample (N = 93). We used a feature selection algorithm to identify a minimal subset of features of the ISRC and tested this subset in a predictive model to investigate if we can accurately predict long-term PTSD outcomes.

RESULTS

We were able to identify a reduced subset of 5 highly predictive features of the ISRC in the model development sample (AUC = 0.80), and we were able to validate those findings in the external validation sample (AUC = 0.84) to discriminate non-remitting vs. resilient trajectories.

CONCLUSION

This study developed and validated a brief 5-item screener in the ED setting, which may help to improve the diagnostic process of PTSD in the acute care setting and help ED clinicians plan follow-up care when patients are still in contact with the healthcare system. This could reduce the burden on patients and decrease the risk of chronic PTSD.

AB1051 CLINICAL OUTCOMES AND HEALTHCARE RESOURCE UTILIZATION OF UNCONTROLLED GOUT PRIOR TO PEGLOTICASE THERAPY

Background

By definition, uncontrolled gout (UG) cannot be managed with oral urate lowering therapies (ULTs) and is associated with substantial morbidity. UG, also known as refractory gout, results in escalated treatment and management. Recent American College of Rheumatology guidelines recommend treating gout to serum uric acid targets; if targets are not achieved or patients continue to have symptoms, pegloticase is recommended. There is a paucity of data documenting the clinical and economic burden of UG patients.

Objectives

Assess clinical outcomes and healthcare resource utilization (HCRU) of UG prior to pegloticase initiation.

Methods

A retrospective observational database analysis was conducted among patients initiating pegloticase between April 1, 2011 and August 31, 2020 using the PharMetrics Plus database. Eligible subjects had ≥1 pegloticase claim (first claim = index date) and continuous enrollment for 24 months prior to index. Relevant clinical and economic (HCRU) outcomes were evaluated over a 24-month pre-index period and compared between two different time intervals prior to index: time interval 1 (Day -720 to Day -361) and time interval 2 (Day -360 to Day -1). Assessment of comorbid disease burden included Charlson Comorbidity Index (CCI) and relevant health conditions. Dependent pairwise comparisons were conducted to compare clinical and economic outcomes between time intervals prior to pegloticase initiation. To assess statistical differences, paired t-tests (continuous variables) or McNemar’s tests (categorical variables) were used.

Results

Of the 408 eligible subjects, most were male (88.5%), with an average age (SD) of 55.2 (11.3) years, 66.9% were between the ages of 45-64 years and 78.2% had a preferred provider organization (PPO) health plan. Most often (34.8% of patients), a rheumatologist was associated with initiation of pegloticase therapy, while primary care physicians accounted for 23.8% of initiations. Mean (SD) CCI score was 2.4 (2.4) with 37.3% of subjects having a CCI score of >3. Prevalence of relevant health conditions over the 24-month pre-index period included tophi (62.5%), urolithiasis (8.6%), chronic kidney disease (34.6%) and chronic pain/fibromyalgia (76.5%), all of which significantly increased from time interval 1 (Day -720 to Day -361) to time interval 2 (Day -360 to Day -1) prior to pegloticase initiation (Table 1). Of patients initiating pegloticase, 57.4% had 1 ULT (excluding probenecid), 11.3% had >2 ULT (excluding probenecid), and 10.3% UG patients had ≥1 probenecid claim over the 24-month pre-index period. Most patients (98.3%) had ≥1 physician office visit, 27.2% had ≥1 hospitalization and 45.3% had ≥1 emergency room (ER) visit over the 24-month pre-index period. HCRU significantly increased from time interval 1 to time interval 2, prior to pegloticase (Figure 1).

Table 1.

Relevant Health Conditions and Disease-specific Health Care Resource Utilization (HCRU)

Overall N= 408Time Interval 1Time Interval 2Tophi62.5%15.4%61.5%***Urolithiasis8.6%4.2%6.9%*Chronic kidney disease34.6%22.5%31.6%***Cardiovascular disease32.6%21.3%28.4%**Type 2 diabetes mellitus31.4%23.3%28.9%**Hypertension76.2%58.1%70.3%***≥1 gout flare87.7%48.5%83.8%***Mean number of gout flare (SD)3.5 (2.4)1.02.1***Gout-related medications ≥1 claim for colchicine56%39.5%63.7%***≥1 claim for opioids71%52.9%60.3%*≥1 claim for oral corticosteroids80%50.2%75.7%***≥1 claim for injectable corticosteroids64%38.5%53.7%***

†Time Interval 1: Day -720 to Day -361 prior to pegloticase initiation; ††Time Interval 2: Day -360 to Day -1 prior to pegloticase initiation

***, p<0.0001; **, p<0.001; *, p<0.05

Conclusion

Overall, these data demonstrate the progressive nature of UG as confirmed by significant increases in gout-related conditions and healthcare resource utilization prior to pegloticase initiation. Further research is needed on healthcare resource utilization among patients with UG post-pegloticase use.

Disclosure of Interests

Robert Morlock Consultant of: Horizon Therapeutics, Victoria Divino Grant/research support from: Horizon Therapeutics, Mitchell DeKoven Grant/research support from: Horizon Therapeutics, Brian LaMoreaux Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Atsuko Powers Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Naina Barretto Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Robert Holt Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Stephanie Taylor Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics

112 Tumor-specific reactivity and effector function of chimeric antigen receptor engineered macrophages targeting MUC1

Background

Chimeric antigen receptors (CAR) have demonstrated remarkable efficacy in licensing T cells for antitumor responses against hematopoietic malignancies but have had limited success against solid tumors. Macrophages, both archetypic phagocytes and professional antigen presenting cells, may exert profound effector functions which complement adaptive cellular immunity.1 Recently, it was shown that human macrophages engineered to express CARs (CAR-Ms) demonstrated antigen-specific phagocytosis, inhibited solid xenograph tumors, and induced an inflammatory tumor microenvironment boosting antitumor T cell responses.2 Kimura et al. previously completed the first prophylactic cancer vaccine trial based on a non-viral antigen, tumor-associated hypoglycosylated Mucin 1 (MUC1).3 A panel of fully-human affinity-matured MUC1-specific antibodies raised in healthy subjects following immunization was identified from these patients.4 Using these MUC1-specific scFv domains for CAR generation, we have now engineered MUC1-targeting CAR-Ms that may potentially possess reduced off-target specificities.

Methods

Lentiviral CAR expression vectors containing the scFv domains of three unique hypoglycosylated MUC1-specific antibodies or a CD20-specific antibody, the CD3zeta signaling domain, and CD28 and OX40 co-stimulatory domains were constructed. The human monocyte/macrophage U937, SC, and THP-1 lines were stably transduced and flow-sort purified to generate MUC1- or CD20-specific CAR-Ms. CAR-Ms were differentiated into macrophages via 48 hour PMA treatment, and subsequently evaluated for antigen-specific function against MUC1- and/or CD20-expressing K562, ZR-75-1, and Raji cells or cancer cells isolated from solid lung tumors or malignant pleural effusions. CAR-M phenotype was evaluated by flow cytometry following in vitro differentiation and polarization with conventional ‘M1’ and ‘M2’ stimuli. Phagocytosis and lysosomal processing of phagocytosed cargo were evaluated by fluorescence microscopy of GFP/CellTrace labeled targets or detection of pH-sensitive pHrodo expression following CAR-M and tumor cell co-culture, respectively. Antigen-specific cytokine production was determined via cytometric bead array following co-culture of CAR-Ms with MUC1- or CD20-expressing tumor cells or 100mer MUC1 peptide.

Results

Differentiated CAR-Ms possessed an inflammatory phenotype expressing IL-8 and CD86 which was further enhanced by IFNgamma or LPS treatment and was resistant to ‘M2’ polarization with conventional stimuli. CAR-Ms exhibited phagocytosis and subsequent lysosomal processing in an antigen-specific manner, with minimal reactivity against tumor cell targets in the absence of the corresponding MUC1 or CD20 antigen. MUC1-specific CAR-Ms stimulated with MUC1 peptide or MUC1+ tumor cells secreted robust levels of pro-inflammatory IL-8, TNFa, and IL-1beta, but not immunosuppressive IL-10.

Conclusions

MUC1-targeting CAR-Ms exert potent tumor-restricted effector function in vitro and may provide a novel treatment strategy either alone or in potential synergistic combination with T cell-mediated immunotherapies.

Acknowledgements

The authors would like to thank Dr. Olivera J. Finn for generously providing reagents and guidance and Dr. Michael T. Lotze for his mentorship. This study was supported by funding from the University of Pittsburgh’s Department of Cardiothoracic Surgery to ACS and RD.

References

Williams CB, Yeh ES, Soloff AC. Tumor-associated macrophages: unwitting accomplices in breast cancer malignancy. Npj Breast Cancer [Internet]. Breast Cancer Research Foundation/Macmillan Publishers Limited; 2016;2:15025. Available from: http://dx.doi.org/10.1038/npjbcancer.2015.25

Klichinsky M, Ruella M, Shestova O, Lu XM, Best A, Zeeman M, et al. Human chimeric antigen receptor macrophages for cancer immunotherapy. Nat Biotechnol 2020;38:947–53.

Kimura T, McKolanis JR, Dzubinski LA, Islam K, Potter DM, Salazar AM, et al. MUC1 Vaccine for Individuals with Advanced Adenoma of the Colon: A Cancer Immunoprevention Feasibility Study. Cancer Prev Res [Internet] 2013;6:18–26. Available from: http://cancerpreventionresearch.aacrjournals.org/content/6/1/18.abstract

Lohmueller JJ, Sato S, Popova L, Chu IM, Tucker MA, Barberena R, et al. Antibodies elicited by the first non-viral prophylactic cancer vaccine show tumor-specificity and immunotherapeutic potential. Sci Rep 2016;6:31740.

Ethics Approval

The study was approved by the University of Pittsburgh’s Institutional Review Board approval number CR19120172-005.

680 Isoforms of neuropilin-2 regulate distinct macrophage functions and are associated with unique tumor-associated macrophages in murine and human breast cancer

Background

Tumor-associated macrophages (TAMs) exert profound influence over breast cancer progression, promoting immunosuppression, angiogenesis, and metastasis.1 Neuropilin-2 (NRP2), consisting of NRP2a and NRP2b isoforms, is a co-receptor for heparin-binding growth factors including VEGF-C and Class 3 Semaphorins. Selective upregulation in response to environmental stimuli and independent signaling pathways endow the NRP2 isoforms with unique functionality.2 3 We have shown that the two isoforms of NRP2 endow opposing functionality to tumor cells due to distinct signaling pathways, with NRP2b promoting metastatic behavior.3 Although NRPs have been shown to regulate macrophage/TAM biology, the role of NRP2 isoforms in TAM functionality has yet to be evaluated.

Methods

To assess the contribution of NRP2 isoforms to macrophage biology, conditional NRP2a and NRP2b knockout mice and stable shRNA knockdown of NRP2a or NRP2b in Raw264.7 macrophages were generated. Phagocytosis, lysosomal processing of phagocytosed cargo, cytokine production, and influence on tumor cell migration were assessed in vitro using NRP2 isoform knockdown macrophages. NRP2 isoform expression was evaluated on TAMs from murine 4T1 and EO771 mammary carcinoma models using spectral cytometry and single-cell qPCR. NRP2 isoforms and approximated immune composition were evaluated in paired primary tumors and distant metastasis using RNAseq in a cohort of 99 breast cancer patients. High-dimensional myeloid phenotyping was performed on malignant pleural effusions (MPEs) from breast cancer patients or effusions of benign origin using 33-color spectral cytometry and unbiased computational analysis.

Results

NRP2 isoform expression was significantly increased in TAMs from murine tumors compared to macrophages from healthy mammary glands. NRP2 isoforms in human primary and metastatic breast cancer were strongly correlated with one another and positively correlated with increased TAMs. Distinct phenotypes of NRP2 isoform-expressing TAMs in were present in 4T1 and EO771 mouse breast cancers and within MPEs from breast cancer patients which were associated with high levels of activation and potential response to a hypoxic tumor niche. Genetic depletion of either NRP2 isoform resulted in dramatic reduction of LPS-induced IL-10 production, defects in phagosomal processing of apoptotic breast cancer cells, and increase in cancer cell migration following co-culture. By contrast, inhibition of IL-6 production was specific in NRP2b knockdown cells while phagocytic uptake of labeled particulates was inhibited only by NPR2a knockdown.

Conclusions

These results demonstrate that NRP2 isoforms regulate both shared and distinct functionality in macrophages and that NRP2 isoform expression identifies unique TAM subsets in breast cancer.

Acknowledgements

This work was supported by awards from the Susan G. Komen Foundation (CCR15329745), U.S. Department of Defense (W81XWH1910650), and American Lung Association/Thoracic Surgery Foundation to ACS. RD was supported by funding from a Department of Veteran's Affairs Career Development Award (CX001771-01A2) and the University of Pittsburgh's Dean Faculty Advancement Award. ESY was supported by the NCI of the NIH under R03 CA245774. MTL was supported by the NCI of the NIH under awards R01CA181450 and R01CA206012 as well as ITTC/UPMCE. RD and ACS were further supported by funding from the Department of Cardiothoracic Surgery.

References

Williams CB, Yeh ES, Soloff AC. Tumor-associated macrophages: unwitting accomplices in breast cancer malignancy. Npj Breast Cancer [Internet]. Breast Cancer Research Foundation/Macmillan Publishers Limited; 2016;2:15025. Available from: http://dx.doi.org/10.1038/npjbcancer.2015.252.

Nasarre P, Gemmill RM, Potiron VA, Roche J, Lu X, Barón AE, et al. Neuropilin-2 is upregulated in lung cancer cells during TGF-β1–Induced epithelial–mesenchymal transition. Cancer Res [Internet] 2013;73:7111 LP–7121. Available from: http://cancerres.aacrjournals.org/content/73/23/7111.abstract3.

Gemmill RM, Nasarre P, Nair-Menon J, Cappuzzo F, Landi L, D'Incecco A, et al. The neuropilin 2 isoform NRP2b uniquely supports TGFβ-mediated progression in lung cancer. Sci Signal [Internet] 2017;10. Available from: http://stke.sciencemag.org/content/10/462/eaag0528.abstract

Ethics Approval

The study was approved by the University of Pittsburgh's Institutional Review Board approval number CR19120172-005.

Aortopulmonary window, left coronary artery aneurysm, and redundant aortic valve leaflet in a calf: the use of multimodal imaging to diagnose congenital heart disease

A 2-month-old male Holstein calf was presented for evaluation of a continuous systolic murmur. A grade V/VI left basilar continuous murmur and a grade IV/VI right basilar continuous murmur was auscultated upon evaluation with increased respiratory effort, wheezes, and crackles. Multimodality diagnostics were performed on this patient for further workup and included transthoracic and transesophageal echocardiography, fluoroscopy guided angiography, and gross necropsy with histopathology. An aortopulmonary window with continuous left-to-right shunting was identified at the level of the left aortic sinus of Valsalva with a severely dilated left coronary artery and left-sided congestive heart failure. This case report outlines the diagnostic workup of a rare congenital heart defect and secondary cardiac abnormalities not previously identified in veterinary literature.

Review of Inpatient Thrombophilia Testing at a Tertiary Care Center

Introduction

Testing for thrombophilic risk factors is common in patients with thrombosis. However, inpatient hereditary thrombophilia work-ups are prone to false-positive and false-negative results due to concurrent acute phase changes, protein consumption, anticoagulation therapy, and liver disease. A recent ASCP Choosing Wisely guideline recommends against measuring protein C (PC), protein S (PS), or antithrombin III (AT3) to diagnose a hereditary deficiency during an active clotting event.

We aimed to review inpatient PC, PS, and AT3 activity assay ordering practices at a tertiary care center. The goal of this study was to determine appropriateness and identify areas for improvement in inpatient thrombophilia ordering practices.

Methods

A retrospective review of inpatients who underwent thrombophilia testing was performed. Inclusion criteria consisted of adult inpatients with PC, PS, and/or AT3 activity results. Patients for whom AT3 was ordered alone were excluded. The timeframe of testing relative to an acute thrombotic event, anticoagulation therapy, and liver disease was determined via electronic medical record review. Other conditions that can affect PC, PS, or AT3 levels were recorded if noted.

Results

Over 5 months, 50 inpatients underwent testing for PC, PS, and/or AT3. Testing was performed within 2 weeks of an acute thrombotic event in 92% of patients; 32% received anticoagulation therapy prior to testing and 16% had liver disease. Test results below the reference range were found in the following percentage of patients: 16% PC, 34% PS, and 16% AT3. In total, 23 of 50 (46%) patients had one or more abnormal results; all 23 had potential confounding conditions/drug.

Conclusions

Inpatient PC, PS, and AT3 testing was frequently performed in clinical settings, which may cause false-positive or false-negative results. This demonstrates the need for increased education and dialogue between the laboratory and clinicians to improve test utilization practices. Potential interventions are currently being analyzed.

The increasing challenge of genetic counseling for cystic fibrosis

Genetic counseling for cystic fibrosis (CF) is challenged by intricate molecular mechanisms, complex phenotypes, and psychosocial needs. CFTR variant interpretation has become critical; this manuscript examines variant nomenclature and classes, as well as opportunities and challenges posed by genetic technologies and genotype-directed therapies. With post-graduate training in medical genetics and counseling, genetic counselors educate patients and families, facilitate testing and interpretation, and help integrate genetic information into diagnosis and treatment. They support families, ranging from carrier couples or new parents, to children understanding their disease, to adults with CF contemplating reproduction. The changing face of CF increasingly highlights the critical importance of genetic information to patients and their families. Genetic counselors are uniquely poised to translate this information in diagnostics and personalized care. Genetic counselors straddle molecular and clinical realms, helping patients adapt, plan, and gain access to appropriate therapies.

Investigating palygorskite's role in the development of mesothelioma in southern Nevada: Insights into fiber-induced carcinogenicity

Similar to asbestos fibers, nonregulated mineral fibers can cause malignant mesothelioma (MM). Recently, increased proportions of women and young individuals with MM were identified in southern Nevada, suggesting that environmental exposure to carcinogenic fibers was causing the development of MM. Palygorskite, a fibrous silicate mineral with a history of possible carcinogenicity, is abundant in southern Nevada. In this study, our aim was to determine whether palygorskite was contributing to the development of MM in southern Nevada. While palygorskite, in vitro, displayed some cytotoxicity toward primary human mesothelial (HM) cells and reduced their viability, the effects were roughly half of those observed when using similar amounts of crocidolite asbestos. No Balb/c (0/19) or MexTAg (0/18) mice injected with palygorskite developed MM, while 3/16 Balb/c and 13/14 MexTAg mice injected with crocidolite did. Lack of MM development was associated with a decreased acute inflammatory response, as injection of palygorskite resulted in lower percentages of macrophages (p = .006) and neutrophils (p = .02) in the peritoneal cavity 3 d after exposure compared to injection of crocidolite. Additionally, compared to mice injected with crocidolite, palygorskite-injected mice had lower percentages of M2 (tumor-promoting) macrophages (p = .008) in their peritoneal cavities when exposed to fiber for several weeks. Our study indicates that palygorskite found in the environment in southern Nevada does not cause MM in mice, seemingly because palygorskite, in vivo, fails to elicit inflammation that is associated with MM development. Therefore, palygorskite is not a likely contributor to the MM cases observed in southern Nevada.

Combined Genetic and Genealogic Studies Uncover a Large BAP1 Cancer Syndrome Kindred Tracing Back Nine Generations to a Common Ancestor from the 1700s

We recently discovered an inherited cancer syndrome caused by BRCA1-Associated Protein 1 (BAP1) germline mutations, with high incidence of mesothelioma, uveal melanoma and other cancers and very high penetrance by age 55. To identify families with the BAP1 cancer syndrome, we screened patients with family histories of multiple mesotheliomas and melanomas and/or multiple cancers. We identified four families that shared an identical BAP1 mutation: they lived across the US and did not appear to be related. By combining family histories, molecular genetics, and genealogical approaches, we uncovered a BAP1 cancer syndrome kindred of ~80,000 descendants with a core of 106 individuals, whose members descend from a couple born in Germany in the early 1700s who immigrated to North America. Their descendants spread throughout the country with mutation carriers affected by multiple malignancies. Our data show that, once a proband is identified, extended analyses of these kindreds, using genomic and genealogical studies to identify the most recent common ancestor, allow investigators to uncover additional branches of the family that may carry BAP1 mutations. Using this knowledge, we have identified new branches of this family carrying BAP1 mutations. We have also implemented early-detection strategies that help identify cancers at early-stage, when they can be cured (melanomas) or are more susceptible to therapy (MM and other malignancies).

Germline BAP1 mutations cause a cancer syndrome characterized by high incidence of mesothelioma (MM), uveal melanoma and other cancers, and by very high penetrance, as all individuals carrying BAP1 mutations developed at least one, and usually several, malignancies throughout their lives. Through screening MM patients with histories of multiple cancers, we found four supposedly unrelated patients that shared an identical germline BAP1 mutation. We investigated whether this BAP1 mutation occurred in a ‘hot-spot’ for “de novo” mutations or whether these four MM patients shared a common ancestor. Using molecular genomics analyses we found that they are related. By genealogic studies we traced their ancestor to a couple that emigrated from Germany to North America in the early 1700’s; we traced the subsequent migration of their descendants, who are now living in at least three different US States. Our findings demonstrate that BAP1 mutations are transmitted among subsequent generations over the course of centuries. This knowledge and methodology is being used to identify additional branches of the family carrying BAP1 mutations. Our study shows that the application of modern genomic analyses, coupled with “classical” family histories collected by the treating physician, and with genealogical searches, offer a powerful strategy to identify high-risk germline BAP1 mutation carriers that will benefit from genetic counseling and early detection cancer screening.

Diagnostic tools and staging of malignant pleural mesothelioma

The diagnosis of malignant pleural mesothelioma remains challenging and should be based on both histologic evidence of invasion and immunohistochemical findings supportive of mesothelioma. Cytology is a controversial method of diagnosis, but may be a useful tool, particularly in the identification of other metastatic malignancies. Malignant pleural mesothelioma must be differentiated from benign, reactive mesothelial proliferations and other metastatic malignancies. Histologic analysis in conjunction with immunohistochemistry, electron microscopy, and limited molecular diagnostics are most useful in establishing a diagnosis. The staging of malignant pleural mesothelioma is most commonly performed using a TNM (tumor, node, metastasis) system proposed by the International Mesothelioma Interest Group.

Abstract LB-220: Minimal asbestos exposure in germline BAP1 heterozygous mice is associated with deregulated inflammatory response and increased risk of mesothelioma

Germline BAP1 mutations predispose to several cancers, in particular malignant mesothelioma (MM). MM pathogenesis is generally associated to professional exposure to asbestos. However, to date we found that none of the mesothelioma patients carrying germline BAP1 mutations were professionally exposed to asbestos. We hypothesized that germline BAP1 mutations might influence the asbestos-induced inflammatory response that is linked to asbestos carcinogenesis, thereby increasing the risk of developing mesothelioma after even minimal exposure.

In a set of short-term experiments, we intraperitoneally injected BAP1+/- and wild-type littermates with low doses of asbestos fibers and analyzed the inflammatory response both at a cellular and humoral level. In a long-term experiment following a similar protocol, we assessed the incidence of MM in mice with and without germline BAP1 mutations and their survival.

We found that, compared to their wild type littermates, BAP1+/- mice exposed to low doses of asbestos fibers showed significant alterations of the peritoneal inflammatory response. In particular, we observed significantly higher levels of pro-tumorigenic alternatively polarized M2 macrophages, and lower levels of several chemokines and cytokines. Consistent with these data, BAP1+/- mice had a significantly higher incidence of mesothelioma after exposure to very low doses of asbestos, and shorter survival.

Our findings suggest that minimal exposure to carcinogenic fibers may significantly increase the risk of malignant mesothelioma in genetically predisposed individuals carrying germline BAP1 mutations, possibly via alterations of the inflammatory response.

Citation Format: A. Napolitano, L. Pellegrini, A. Dey, D. Larson, M. Tanji, E. G. Flores, B. Kendrick, D. Lapid, A. Powers, S. Kanodia, S. Pastorino, H. I. Pass, V Dixit, H. Yang, M. Carbone. Minimal asbestos exposure in germline BAP1 heterozygous mice is associated with deregulated inflammatory response and increased risk of mesothelioma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-220. doi:10.1158/1538-7445.AM2015-LB-220

Abstract 3944: High incidence of somatic BAP1 alterations in sporadic malignant mesothelioma

Background: Malignant mesothelioma (MM) is a lethal tumor whose pathogenesis results from complex interactions between host genetics and environmental carcinogens. BAP1 mutations were reported in 22% and 23% of sporadic MM in two US Caucasian studies whereas BAP1 mutations were found in 61% of sporadic MM in a Japanese study. The significant discrepancy in frequency of BAP1 mutations suggested either a possible influence of ethnicity or differences related to the methodological approaches. Methods: To investigate this apparent discrepancy, we carried out comprehensive genomic analyses using multiple techniques in order to detect somatic alterations of the BAP1 gene in tumors of 22 US Caucasian MM patients. Results: Six mutations were detected by Sanger sequencing, gross gene alterations were found in 7 MM specimens by Multiplex Ligation-Dependent Probe Amplification and copy number analysis, and a new splice variant was identified by cDNA sequencing. Changes in methylation were not observed in our study. Immunohistochemistry (IHC) revealed nuclear BAP1 staining in the 8 MM tumors containing wild-type BAP1 while tumor cells in the 14 biopsies with mutated BAP1 did not show any nuclear staining. We extended our BAP1 IHC analysis to an independent cohort of MM samples from the National Virtual Mesothelioma Bank and we found loss of BAP1 nuclear staining in 46 out of 67 biopsies. Moreover we found similar frequency of BAP1 loss across different MM histological subtypes. Conclusions: We identified somatic alterations of the BAP1 gene in 73.7% of Caucasian MM tumors in two independent cohorts of somatic MMs, underscoring the need to apply integrated genomic analyses to scrutinize the BAP1 gene for its alterations. Immunohistochemistry was the most reliable technique to detect BAP1 mutations in MM biopsies. The high incidence of alterations establishes BAP1 as the most commonly mutated gene in MM, regardless of ethnic background or histological subtype.

Citation Format: Masaki Nasu, Sandra Pastorino, Hugh Luk, Erin Flores, Francine Baumann, Amy Powers, Shreya Kanodia, Giovanni Gaudino, Yu-an Zhang, Adi Gazdar, Haining Yang, Harvey I. Pass, Mitsuru Emi, Michele Carbone. High incidence of somatic BAP1 alterations in sporadic malignant mesothelioma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3944. doi:10.1158/1538-7445.AM2015-3944

Minimal asbestos exposure in germline BAP1 heterozygous mice is associated with deregulated inflammatory response and increased risk of mesothelioma

Germline BAP1 mutations predispose to several cancers, in particular malignant mesothelioma. Mesothelioma is an aggressive malignancy generally associated with professional exposure to asbestos. However, to date, we found that none of the mesothelioma patients carrying germline BAP1 mutations were professionally exposed to asbestos. We hypothesized that germline BAP1 mutations might influence the asbestos-induced inflammatory response that is linked to asbestos carcinogenesis, thereby increasing the risk of developing mesothelioma after minimal exposure. Using a BAP1(+/-) mouse model, we found that, compared with their wild-type littermates, BAP1(+/-) mice exposed to low-dose asbestos fibers showed significant alterations of the peritoneal inflammatory response, including significantly higher levels of pro-tumorigenic alternatively polarized M2 macrophages, and lower levels of several chemokines and cytokines. Consistent with these data, BAP1(+/-) mice had a significantly higher incidence of mesothelioma after exposure to very low doses of asbestos, doses that rarely induced mesothelioma in wild-type mice. Our findings suggest that minimal exposure to carcinogenic fibers may significantly increase the risk of malignant mesothelioma in genetically predisposed individuals carrying germline BAP1 mutations, possibly via alterations of the inflammatory response.

Evaluation of clonal origin of malignant mesothelioma

Background

The hypothesis that most cancers are of monoclonal origin is often accepted as a fact in the scientific community. This dogma arose decades ago, primarily from the study of hematopoietic malignancies and sarcomas, which originate as monoclonal tumors. The possible clonal origin of malignant mesothelioma (MM) has not been investigated. Asbestos inhalation induces a chronic inflammatory response at sites of fiber deposition that may lead to malignant transformation after 30-50 years latency. As many mesothelial cells are simultaneously exposed to asbestos fibers and to asbestos-induced inflammation, it may be possible that more than one cell undergoes malignant transformation during the process that gives rise to MM, and result in a polyclonal malignancy.

Methods and results

To investigate the clonality patterns of MM, we used the HUMARA (Human Androgen Receptor) assay to examine 16 biopsies from 14 women MM patients. Out of 16 samples, one was non-informative due to skewed Lyonization in its normal adjacent tissue. Fourteen out of the 15 informative samples revealed two electrophoretically distinct methylated HUMARA alleles, the Corrected Allele Ratio (CR) calculated on the allele peak areas indicating polyclonal origin MM.

Conclusions

Our results show that MM originate as polyclonal tumors and suggest that the carcinogenic “field effect” of mineral fibers leads to several premalignant clones that give rise to these polyclonal malignancies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-014-0301-3) contains supplementary material, which is available to authorized users.

Cancer patient perceptions about biobanking and preferred timing of consent

Little is known about how cancer patients feel about donating their tissue, especially in a multiethnic population. Structured interviews were conducted with 30 patients recently diagnosed with cancer, referred to the study by six cancer surgeons and oncologists and by other patients in the study. The participants reported a variety of cancers, and the sample reflected the racial distribution of Hawai`i, including Caucasians (23%), Native Hawaiians and Pacific Islanders (27%), Asians (37%), Hispanics (7%), Native Americans (3%), and African Americans (3%). The interview questions and analysis were guided by the Framework Approach, with interview questions based on pre-set aims. Findings suggest that most cancer patients would donate cancer tissue to science, especially if informed that doing so could help researchers find causes of and cures for cancer. Patients varied on when in their cancer journey they would be most receptive to being asked for a donation, however two-thirds thought they would be more receptive if approached after surgery. Only three of the 30 patients said they would want to be re-consented each time their tissue is requested for research. They identified their physician as the preferred messenger regarding tissue donation. No obvious differences were seen by race. Findings confirm those of other researchers who have reported broad support for biobank participation if informed consent and confidentiality could be assured. Given that the physician was seen as the key messenger about biobanking, more education is needed around cancer tissue collection for physicians, as well as for cancer patients.

Abstract 446: BAP1 mutation in mesothelioma and “BAP1 Cancer Syndrome”

Malignant mesothelioma (MM) is a lethal cancer whose pathogenesis results from complex interactions between host genetics and environmental carcinogens, such as asbestos and erionite fibers. Recently, BAP1 (BRCA associated protein 1) has been identified as a novel MM tumor suppressor gene located at 3p21, a region frequently deleted in MM, which encodes for a deubiquitinase enzyme known to target histones and other proteins.

We discovered that germline BAP1 mutations cause a novel cancer syndrome characterized by a significant excess of both pleural and peritoneal MM, uveal and cutaneous melanoma and possibly other tumors. In the same study, we reported that 22% sporadic MM tumors, among the Caucasian population, harbored somatic BAP1 mutations. Several other studies supported a relevant role of BAP1 in MM. However, a significant variation in the frequency of BAP1 mutation was found across different studies and populations. In fact, one research group found BAP1 gene altered in 61% of tumor samples from a Japanese cohort, pointing out to a possible influence of ethnicity on the prevalence of BAP-1 alterations among MM patients. However, the limitations in tumor sample sizes and methodological differences across studies do not allow for conclusive associations. We are now further analyzing BAP1 status and possible clinicopathological associations using different and more sensitive methods, such as MPLA, DNA and RNA sequencing, DNA copy number and methylation. Our preliminary results indicate that, regardless of ethnicity, BAP1 plays a crucial role in MM pathogenesis. More experiments are urgently needed to see whether BAP1 expression could be used in diagnostic, prognostic, or therapeutic settings. The impact of this work will extend to other cancers with BAP1 mutations.

Citation Format: Masaki Nasu, Andrea Napolitano, Sandra Pastorino, Mika Tanji, Erin Flores, Francine Baumann, Amy Powers, Giovanni Gaudino, Harvey I. Pass, Haining Yang, Michele Carbone. BAP1 mutation in mesothelioma and “BAP1 Cancer Syndrome”. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 446. doi:10.1158/1538-7445.AM2014-446

Abstract 3188: Evaluation of clonal origin of malignant mesothelioma/polyclonal origin of malignant mesothelioma

Tumors are generally thought to be monoclonal in origin, although this paradigm stemmed decades ago mostly from the study of hematopoietic malignancies and sarcomas. The clonal origin of malignant mesothelioma, a deadly cancer resistant to the current therapies, has never been investigated before. We used the HUMARA (human androgen receptor) assay to examine the pattern of clonality in 14 sporadic and 2 familial Malignant Mesotheliomas (MM). Of 16 specimens studied, 14 were informative and nearly all (13/14) revealed two electrophoretically distinct methylated HUMARA alleles, indicating a polyclonal origin for these tumors. This discovery has important clinical implications, in that an accurate assessment of tumor clonality is key to the design of novel molecular strategies for the treatment of MM.

Citation Format: Sabahattin Comertpay, Rosanna Mezzapelle, Mika Tanji, Oriana Strianese, Harvey I. Pass, Tracey Weigel, Joseph Friedberg, Paul Sugarbaker, Thomas Krausz, Ena Wang, Giovanni Gaudino, Haining Yang, Amy Powers, Barbara Parsons, Sandra Pastorino, Michele Carbone. Evaluation of clonal origin of malignant mesothelioma/polyclonal origin of malignant mesothelioma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3188. doi:10.1158/1538-7445.AM2014-3188

Human papillomavirus genotype prevalence in invasive penile cancers from a registry-based United States population

Background: Human papillomavirus (HPV) is estimated to play an etiologic role in 40–50% of penile cancers worldwide. Estimates of HPV prevalence in U.S. penile cancer cases are limited.

Methods: HPV DNA was evaluated in tumor tissue from 79 invasive penile cancer patients diagnosed in 1998–2005 within the catchment areas of seven U.S. cancer registries. HPV was genotyped using PCR-based Linear Array and INNO-LiPA assays and compared by demographic, clinical, and pathologic characteristics and survival. Histological classification was also obtained by independent pathology review.

Results: HPV DNA was present in 50 of 79 (63%) of invasive penile cancer cases. Sixteen viral genotypes were detected. HPV 16, found in 46% (36/79) of all cases (72% of HPV-positive cases) was the most prevalent genotype followed equally by HPV 18, 33, and 45, each of which comprised 5% of all cases. Multiple genotypes were detected in 18% of viral positive cases. HPV prevalence did not significantly vary by age, race/ethnicity, population size of geographic region, cancer stage, histology, grade, penile subsite, or prior cancer history. Penile cases diagnosed in more recent years were more likely to be HPV-positive. Overall survival did not significantly vary by HPV status.

Conclusion: The relatively high prevalence of HPV in our study population provides limited evidence of a more prominent and, possibly, increasing role of infection in penile carcinogenesis in the U.S. compared to other parts of the world.

Molecular testing for cystic fibrosis carrier status practice guidelines: recommendations of the National Society of Genetic Counselors

PURPOSE

To provide practice recommendations for genetic counselors whose clients are considering cystic fibrosis (CF) carrier testing or seeking information regarding CF molecular test results. The goals of these recommendations are to: 1) Provide updated information about the natural history, diagnosis, and treatment of CF and related conditions. 2) Supplement genetic counselors' knowledge and understanding of the available carrier screening and diagnostic testing options. 3) Describe the current state of genotype/phenotype correlations for CFTR mutations and an approach to interpreting both novel and previously described variants. 4) Provide a framework for genetic counselors to assist clients' decision-making regarding CF carrier testing, prenatal diagnosis, and pregnancy management. Disclaimer The practice guidelines of the National Society of Genetic Counselors (NSGC) are developed by members of the NSGC to assist genetic counselors and other health care providers in making decisions about appropriate management of genetic concerns; including access to and/or delivery of services. Each practice guideline focuses on a clinical or practice-based issue, and is the result of a review and analysis of current professional literature believed to be reliable. As such, information and recommendations within the NSGC practice guidelines reflect the current scientific and clinical knowledge at the time of publication, are only current as of their publication date, and are subject to change without notice as advances emerge.In addition, variations in practice, which take into account the needs of the individual patient and the resources and limitations unique to the institution or type of practice, may warrant approaches, treatments and/or procedures that differ from the recommendations outlined in this guideline. Therefore, these recommendations should not be construed as dictating an exclusive course of management, nor does the use of such recommendations guarantee a particular outcome. Genetic counseling practice guidelines are never intended to displace a health care provider's best medical judgment based on the clinical circumstances of a particular patient or patient population.Practice guidelines are published by NSGC for educational and informational purposes only, and NSGC does not "approve" or "endorse" any specific methods, practices, or sources of information.

Successful implementation of a longitudinal, integrated pathology curriculum during the third year of medical school

CONTEXT

There are few published examples of pathology instruction during the clinical years of medical student training. This lack of exposure to pathology may lead to poor understanding of laboratory testing and the role of pathologists in patient care.

OBJECTIVE

To design, implement, and evaluate a pathology curriculum integrated into a longitudinal clerkship for third-year medical students.

DESIGN

The curriculum includes an introductory session during the transition week course, pathologist participation in longitudinal student case conferences, and a pathology elective. The curriculum was evaluated by using surveys consisting of both multiple choice and written responses.

RESULTS

A total of 55 students participated in the longitudinal curriculum during the 2009-2010 academic year and 8 students, only one of whom stated a career interest in pathology, participated in the elective. More than 80 pathology topics were discussed and, for the first time, pathologists received teaching awards from the third-year students. All elective students would recommend the elective to colleagues; feedback also suggested an improved understanding of pathology as a profession. At the end of the year, 31% of all students, compared to only 19% in the initial survey, knew that most of an anatomic pathologist's caseload consists of specimens from living patients (P  =  .13). In addition, elective student interaction with a pathology faculty member directly led to an improvement in test reporting.

CONCLUSIONS

A novel longitudinal curriculum allowed for the creative integration of pathology into third-year students' clinical training and led to better student understanding of the role of pathologists in patient care.

Cancer cell secretion of the DAMP protein HMGB1 supports progression in malignant mesothelioma

Human malignant mesothelioma is an aggressive and highly lethal cancer that is believed to be caused by chronic exposure to asbestos and erionite. Prognosis for this cancer is generally poor because of late-stage diagnosis and resistance to current conventional therapies. The damage-associated molecular pattern protein HMGB1 has been implicated previously in transformation of mesothelial cells. Here we show that HMGB1 establishes an autocrine circuit in malignant mesothelioma cells that influences their proliferation and survival. Malignant mesothelioma cells strongly expressed HMGB1 and secreted it at high levels in vitro. Accordingly, HMGB1 levels in malignant mesothelioma patient sera were higher than that found in healthy individuals. The motility, survival, and anchorage-independent growth of HMGB1-secreting malignant mesothelioma cells was inhibited in vitro by treatment with monoclonal antibodies directed against HMGB1 or against the receptor for advanced glycation end products, a putative HMGB1 receptor. HMGB1 inhibition in vivo reduced the growth of malignant mesothelioma xenografts in severe-combined immunodeficient mice and extended host survival. Taken together, our findings indicate that malignant mesothelioma cells rely on HMGB1, and they offer a preclinical proof-of-principle that antibody-mediated ablation of HMBG1 is sufficient to elicit therapeutic activity, suggesting a novel therapeutic approach for malignant mesothelioma treatment.

Abstract 1557: High mobility group box 1 secretion supports tumor progression of human malignant mesothelioma

Human malignant mesothelioma (MM) is an aggressive and highly lethal cancer, often associated with exposure to asbestos and erionite. Prognosis is poor, due to late-stage diagnosis and resistance to current conventional therapies. We previously showed that high-mobility group box-1 protein (HMGB1), a damage-associated molecular pattern (DAMP) protein, is involved in the early stages of mesothelial cell transformation. Here we show that HMGB1 establishes an autocrine circuit in MM cells influencing tumor cell proliferation and survival. MM cells express HMGB1 at high levels and secrete HMGB1 into the extracellular space. Accordingly, HMGB1 levels in MM patients’ sera are significantly higher than in those of healthy individuals. In addition, motility, survival and anchorage-independent growth of HMGB1-secreting MM cells were inhibited in vitro by a monoclonal antibody (mAb) against HMGB1, by the recombinant HMGB1 competitive antagonist BoxA and by antibodies against the receptor for advanced glycation end products (RAGE). Inhibition of HMGB1 reduced the growth of MM xenografts in SCID mice and extended survival. Our findings indicate that MM cells become “addicted” to HMGB1 and that targeting HMGB1 can be a promising novel therapeutic approach for MM.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1557. doi:1538-7445.AM2012-1557

Culex flavivirus isolates from mosquitoes in Guatemala

A new strain of Culex flavivirus (family Flaviviridae, genus Flavivirus, CxFV), an insect virus first described in Japan, was isolated from adult Culex quinquefasciatus Say (Diptera: Culicidae) collected in 2006 from Izabal Department on the Caribbean coast of Guatemala. Mosquito pools were assayed for flavivirus RNA by using flavivirus group-specific primers that amplified a 720-bp region of the nonstructural (NS) 5 gene by standard reverse transcriptase-polymerase chain reaction. From 210 pools (1,699 mosquitoes), eight tested positive, and six of these mosquito pools produced virus isolates in Aedes albopictus Skuse C6/36 cells. Nucleotide sequence comparison of the eight flavivirus RNA-positive pools showed that there was 100% identity among them, and phylogenetic analysis of the NS5 and envelope gene regions indicated that they represent a strain of the recently described CxFV from Japan. This is the first report of an insect flavivirus from Central America.

Molecular analyses, morphology and immunohistochemistry together differentiate pleural synovial sarcomas from mesotheliomas: clinical implications

BACKGROUND

Only recently pleural synovial sarcomas (SS) have been definitively identified because of the presence of a characteristic X;18 translocation. SS are sarcomatoid or biphasic malignancies morphologically almost indistinguishable from sarcomatoid or biphasic malignant mesotheliomas (MM).

PATIENT AND METHODS

We demonstrated a primary pleural biphasic SS in a patient referred to us has having a biphasic MM.

RESULTS

Histology showed a spindle cell tumor with focal epithelioid differentiation, microcalcifications, and a hemangiopericytomatous vascular pattern. Ultrastructurally, the epithelioid tumor cells had few blunt microvilli and occasional intercellular junctions. Immunohistochemically the tumor cells were positive for BCL-2, CD99, CD56, and focally for BerEp4, Pancytokeratin and cytokeratin 5/6. These findings suggested the possibility of SS rather than MM. Detection of the t(X:18) translocation using RT-PCR, Southern blot, and DNA sequencing definitively confirmed the diagnosis of SS.

CONCLUSION

The differential between pleural SS and MM requires a high degree of suspicion and molecular analyses because morphology (histology, immunohistochemistry and electron microscopy) is insufficient to definitively distinguish between these two malignancies. This differential is critical because patients with pleural SS can be susceptible to chemotherapy, and accordingly are treated, while patients with sarcomatoid MM are resistant to chemotherapy and accordingly are not treated.

The role of environmental carcinogens, viruses and genetic predisposition in the pathogenesis of mesothelioma

Mesothelioma is one of the most aggressive human cancers and kills approximately 2500 people per year in the US. This cancer was almost unknown until the second half of the 20th century, and its rapid increase has been linked to the widespread use of asbestos. In spite of an enormous research effort, the mechanisms of asbestos carcinogenicity have remained an enigma. Why only a fraction of individuals exposed to high levels of asbestos develop mesothelioma while individuals with low to no asbestos exposure also develop this cancer remains unknown. Recently, simian virus 40, a DNA tumor virus known to preferentially cause mesotheliomas in hamsters, and genetic factors have been linked to mesothelioma development. Therefore, a new research front has been opened in mesothelioma, a cancer that appears to be caused by the environmental carcinogens asbestos and erionite, viruses, and genetic predisposition. The challenge for future research is to establish how these apparently very different factors interact to cause mesotheliomas.