A liquid biopsy for detecting circulating mesothelial precursor cells: A new biomarker for diagnosis and prognosis in mesothelioma

BACKGROUND

Malignant pleural mesothelioma (MPM) is an aggressive cancer related to asbestos exposure. Early diagnosis is challenging due to generic symptoms and a lack of biomarkers. We previously demonstrated that mesothelial precursor cells (MPC) characterized by mesothelin (MSLN)+CD90+CD34+ could be implicated in the development of mesothelioma after asbestos exposure. Here, we aimed to determine the clinical significance of detecting MPC in blood for early-stage diagnosis and prognosis of mesothelioma.

METHODS

Due to the rarity of MPC in blood, it is challenging to identify this cell population using conventional techniques. Hence, we have developed a microfluidic liquid biopsy platform called MesoFind that utilizes an immunomagnetic, mesothelin capture strategy coupled with immunofluorescence to identify rare populations of cells at high sensitivity and precision. To validate our technique, we compared this approach to flow cytometry for the detection of MPC in murine blood and lavage samples. Upon successful validation of the murine samples, we then proceeded to examine circulating MPC in 23 patients with MPM, 23 asbestos-exposed individuals (ASB), and 10 healthy donors (HD) to evaluate their prognostic and diagnostic value.

FINDING

MPC were successfully detected in the blood of murine samples using MesoFind but were undetectable with flow cytometry. Circulating MPC were significantly higher in patients with epithelioid MPM compared to HD and ASB. The MPC subpopulation, MSLN+ and CD90+, were upregulated in ASB compared to HD suggesting an early role in pleural damage from asbestos. The MPC subpopulation, MSLN+ and CD34+, in contrast, were detected in advanced MPM and associated with markers of poor prognosis, suggesting a predominant role during cancer progression.

INTERPRETATION

The identification of circulating MPC presents an attractive solution for screening and early diagnosis of epithelioid mesothelioma. The presence of different subtypes of MPC have a prognostic value that could be of assistance with clinical decisions in patients with MPM.

FUNDING

Princess Margaret Hospital Foundation Mesothelioma Research Fund, Toronto General & Western Hospital Foundation.

Foxp3+ Regulatory T Cell Depletion after Nonablative Oligofractionated Irradiation Boosts the Abscopal Effects in Murine Malignant Mesothelioma

Increasing evidence indicates that local hypofractionated radiotherapy (LRT) can elicit both immunogenic and immunosuppressive local and systemic immune responses. We thus hypothesized that blockade of LRT-induced immunosuppressive responses could augment the antitumor effects and induce an abscopal response. In this study, we found that the upregulation of Foxp3⁺ regulatory T cells (Tregs) in the mesothelioma tumor microenvironment after nonablative oligofractionated irradiation significantly limited the success of irradiation. Using DEREG mice, which allow conditional and efficient depletion of Foxp3⁺ Tregs by diphtheria toxin injection, we observed that transient Foxp3⁺ Treg depletion immediately after nonablative oligofractionated irradiation provided synergistic local control and biased the T cell repertoire toward central and effector memory T cells, resulting in long-term cure. Furthermore, this combination therapy showed significant abscopal effect on the nonirradiated tumors in a concomitant model of mesothelioma through systemic activation of cytotoxic T cells and enhanced production of IFN-γ and granzyme B. Although local control was preserved with one fraction of nonablative irradiation, three fractions were required to generate the abscopal effect. PD-1 and CTLA-4 were upregulated on tumor-infiltrating CD4⁺ and CD8⁺ T cells in irradiated and nonirradiated tumors, suggesting that immune checkpoint inhibitors could be beneficial after LRT and Foxp3⁺ Treg depletion. Our findings are applicable to the strategy of immuno-radiotherapy for generating optimal antitumor immune responses in the clinical setting. Targeting Tregs immediately after a short course of irradiation could have a major impact on the local response to irradiation and its abscopal effect.

Long-term Outcomes of Lung Transplant With Ex Vivo Lung Perfusion

Importance

The mortality rate for individuals on the wait list for lung transplant is 15% to 25%, and still only 20% of lungs from multiorgan donors are used for lung transplant. The lung donor pool may be increased by assessing and reconditioning high-risk extended criteria donor lungs with ex vivo lung perfusion (EVLP), with similar short-term outcomes.

Objective

To assess the long-term outcomes of transplant recipients of donor lungs treated with EVLP.

Design, Setting, and Participants

This retrospective cohort single-center study was conducted from August 1, 2008, to February 28, 2017, among 706 recipients of donor lungs not undergoing EVLP and 230 recipients of donor lungs undergoing EVLP.

Exposure

Donor lungs undergoing EVLP.

Main Outcomes and Measures

The incidence of chronic lung allograft dysfunction and allograft survival during the 10-year EVLP era were the primary outcome measures. Secondary outcomes included donor characteristics, maximum predicted percentage of forced expiratory volume in 1 second, acute cellular rejection, and de novo donor-specific antibody development.

Results

This study included 706 patients (311 women and 395 men; median age, 50 years [interquartile range, 34-61 years]) in the non-EVLP group and 230 patients (85 women and 145 men; median age, 46 years [interquartile range, 32-55 years]) in the EVLP group. The EVLP group donors had a significantly lower mean (SD) Pao2:fraction of inspired oxygen ratio than the non-EVLP group donors (348 [108] vs 422 [88] mm Hg; P < .001), higher prevalence of abnormal chest radiography results (135 of 230 [58.7%] vs 349 of 706 [49.4%]; P = .02), and higher proportion of smoking history (125 of 204 [61.3%] vs 322 of 650 [49.5%]; P = .007). More recipients in the EVLP group received single-lung transplants (62 of 230 [27.0%] vs 100 of 706 [14.2%]; P < .001). There was no significant difference in time to chronic lung allograft dysfunction between the EVLP and non-EVLP group (70% vs 72% at 3 years; 56% vs 56% at 5 years; and 53% vs 36% at 9 years; log-rank P = .68) or allograft survival between the EVLP and non-EVLP groups (73% vs 72% at 3 years; 62% vs 58% at 5 years; and 50% vs 44% at 9 years; log-rank P = .97) between the 2 groups. All secondary outcomes were similar between the 2 groups.

Conclusions and Relevance

Since 2008, 230 of 936 lung transplants (24.6%) in the Toronto Lung Transplant Program were performed after EVLP assessment and treatment. Use of EVLP-treated lungs led to an increase in the number of patients undergoing transplantation, with comparable long-term outcomes.

Impact of donor time to cardiac arrest in lung donation after circulatory death

OBJECTIVE

Acceptance of lungs from donation after circulatory determination of death has been generally restricted to donors who have cardiac arrest within 60 minutes after withdrawal of life-sustaining therapies. We aimed to determine the effect of the interval between withdrawal of life-sustaining therapies to arrest and recipient outcomes. Second, we aimed to compare outcomes between donation after circulatory determination of death transplants and donation after neurologic determination of death transplants.

METHODS

A single-center, retrospective review was performed analyzing the clinical outcomes of transplant recipients who received donation after circulatory determination of death lungs and those who received donation after neurologic determination of death lungs. Donation after circulatory determination of death cases were then grouped on the basis of the interval between withdrawal of life-sustaining therapies and asystole: 0 to 19 minutes (rapid), 20 to 59 minutes (intermediate), and more than 60 minutes (long). Recipient outcomes from each of these groups were compared.

RESULTS

A total of 180 cases of donation after circulatory determination of death and 1088 cases of donation after neurologic determination of death were reviewed between 2007 and 2017. There were no significant differences in the 2 groups in terms of age, gender, recipient diagnosis, and type of transplant (bilateral vs single). Ex vivo lung perfusion was used in 118 of 180 (65.6%) donation after circulatory determination of death cases and 149 of 1088 (13.7%) donation after neurologic determination of death cases before transplantation. The median survivals of recipients who received donation after circulatory determination of death lungs versus donation after neurologic determination of death lungs were 8.0 and 6.9 years, respectively. Time between withdrawal of life-sustaining therapies and asystole was available for 148 of 180 donors (82.2%) from the donation after circulatory determination of death group. Mean and median time from withdrawal of life-sustaining therapies to asystole were 28.6 minutes and 16 minutes, respectively. Twenty donors required more than 60 minutes to experience cardiac arrest, with the longest duration being 154 minutes before asystole was recorded. Recipients of donation after circulatory determination of death lungs who had cardiac arrest at 0 to 19 minutes (90 donors), 20 to 59 minutes (38 donors), and more than 60 minutes (20 donors) did not demonstrate any significant differences in terms of short- and long-term survivals, primary graft dysfunction 2 and 3, intensive care unit stay, mechanical ventilation days, or total hospital stay.

CONCLUSIONS

Short- and long-term outcomes in recipients who received donation after neurologic determination of death versus donation after circulatory determination of death lungs are similar. Different withdrawals of life-sustaining therapies to arrest intervals were not associated with recipient outcomes. The maximum acceptable duration of this interval has yet to be established.

Initial lung transplantation experience with uncontrolled donation after cardiac death in North America

Uncontrolled donation after cardiac death (uDCD) has the potential to ameliorate the shortage of suitable lungs for transplant. To date, no lung transplant data from these donors are available from North America. We describe the successful use of these donors using a simple method of in situ lung inflation so that the organ can be protected from warm ischemic injury. Forty-four potential donors were approached, and family consent was obtained in 30 cases (68%). Of these, the lung transplant team evaluated 16 uDCDs on site, and 14 were considered for transplant pending ex vivo lung perfusion assessment. Five lungs were ultimately used for transplant (16.7% use rate from consented donors). The mean warm ischemic time was 2.8 hours. No primary graft dysfunction grade 3 was observed at 24, 48, or 72 hours after transplant. Median intensive care unit stay was 5 days (range: 2-78 days), and median hospital stay was 17 days (range: 8-100 days). The 30-day mortality was 0%. Four of 5 patients are alive at a median of 651 days (range: 121-1254 days) with preserved lung function. This study demonstrates the proof of concept and the potential for uDCD lung donation using a simple donor intervention.

Simultaneous Vs Sequential Retroperitoneal, Thoracic and Cervical Resection of Post Chemotherapy Residual Masses in Patients With Metastatic Nonseminomatous Germ Cell Tumors of the Testis

OBJECTIVE

To compare a simultaneous vs sequential approach to residual post chemotherapy mass resections in metastatic testis cancer.

METHODS

A retrospective review was performed of patients who underwent retroperitoneal and thoracic/cervical resection of post chemotherapy residual masses between 2002 and 2018. Group 1: "Simultaneous" (Combined Retroperitoneal and Thoracic/Cervical resections on the same date); Group 2: "Sequential" (Retroperitoneal and Thoracic/Cervical resections at separate dates).

RESULTS

During the study period, 35 simultaneous and 17 sequential resections were performed. The median age at surgery was 28 years (Range 16-61). The median follow-up from last surgical procedure was 62.7 months (Range 0.4-194). Histology revealed teratoma in 38 (73.1%) patients, necrosis in 8 (15.4%) and viable tumor in 6 (11.5%). Discordant pathology findings between thoracic/cervical and abdominal resections were noted in 16 (30.8%) patients. No differences were observed between the simultaneous vs sequential groups in median operating time (585 minutes vs 545 minutes, P = .64), blood loss (1300 vs 1300 mls, P = .42), or length of stay (9 vs 11 days, P = .14). There was no difference between the 5-year (65.7% vs 68.6%) relapse-free survival between the 2 groups (P = .84) or the 5-year (88.6% vs 100%) overall and disease-specific survival (P = .25).

CONCLUSION

Simultaneous resection of retroperitoneal and thoracic/cervical post chemotherapy metastases is a feasible in some patients. It requires multidisciplinary collaboration and a longer primary procedure.

Incidence of Ipsilateral Side Recurrence After Open or Video-Assisted Thoracic Surgery Resection of Colorectal Lung Metastases

BACKGROUND

There is still controversy whether full lung palpation is required for patients undergoing pulmonary metastasectomy. We aimed to compare pulmonary ipsilateral recurrence (IR) after video-assisted thoracic surgery (VATS) or open surgery.

METHODS

A retrospective study of all patients who underwent surgery for colorectal cancer lung metastases between 2003 and 2012 was performed. IR rate was compared between the 2 groups after adjusting for a propensity score matching based on age, sex, disease-free interval, number of metastases, type of resection, presence of a cardiovascular risk factor, presence of a respiratory risk factor, as well as the interaction between the number of metastases and the disease-free interval. The propensity score was used for matched and weighted comparisons of VATS and open patients.

RESULTS

A total of 211 patients underwent surgery for colorectal cancer lung metastases. Of these, 75 (35.5%) were performed via VATS and 136 (64.5%) via open surgery. Before matching, 118 (55.9%) were male and the median age at the time of metastases diagnosis was 61 (range, 49.8-72.2) years. Median disease free-interval was 20 (19.7 ± 28.3) months; 22 (21.6 ± 28.5) months in VATS and 19 (19.0 ± 28.3) months in open surgery. In total, 19 (25.3%) developed IR in VATS, and 39 (28.7%) in open surgery. Five-year overall survival was 53.1% (61.9% VATS; 49.2% open). In the matched sample, IR was 23.6% in VATS vs 26.2% in open surgery (95% confidence interval for risk reduction with VATS: -22.6% to 17.5%; P = .80).

CONCLUSIONS

No significant difference was observed in IR rates between VATS and open surgery in the treatment of colorectal cancer lung metastases.

Prognostic influence of tumor microenvironment after hypofractionated radiation and surgery for mesothelioma

OBJECTIVE

Cytotoxic CD8+ tumor infiltrating lymphocytes (TILs) can contribute to the benefit of hypofractionated radiation, but programmed cell death pathways (programmed cell death 1 and programmed cell death ligand 1 [PD-1/PD-L1]) may provide a mechanism of tumor immune escape. We therefore reviewed the influence of PD-1/PD-L1 and CD8+ TILs on survival after accelerated hypofractionated hemithoracic radiation followed by extrapleural pneumonectomy for malignant pleural mesothelioma (MPM).

METHODS

Sixty-nine consecutive patients undergoing the protocol of Surgery for Mesothelioma after Radiation Therapy (SMART) between November 2008 and February 2016 were analyzed for the presence of PD-L1 on tumor cells, PD-1 on inflammatory cells, and CD8+ TILs. Comparison was made with a cohort of patients undergoing extrapleural pneumonectomy after induction chemotherapy (n = 14) and no induction (n = 2) between March 2005 and October 2008. PD-L1 expression on tumor cells ≥1% was considered positive. CD8+ TILs and PD-1 expression were scored as a percentage of positive cells.

RESULTS

PD-L1 was negative in 75% of MPM after completion of SMART. CD8+ TILs ranged between 0.24% and 8.47% (median 2%). CD8+ TILs ≥2% was associated with significantly better survival in epithelioid MPM (median survival 3.7 years vs 2.3 years in CD8+ TILs <2%; P = .02). PD-L1 positivity was associated with worse survival in biphasic MPM (median survival, 0.4 years vs 1.5 years in biphasic PD-L1 negative tumors; P = .07) after SMART. Multivariate analysis demonstrated that epithelioid MPM, nodal disease, and CD8+ TILs were independent predictors of survival after SMART.

CONCLUSIONS

The influence of tumor microenvironment on survival differs between epithelioid and nonepithelioid MPM. CD8+ TILs is an independent factor associated with better survival in epithelioid MPM treated with SMART.

Routine Edmonton Symptom Assessment System (ESAS) scores in epithelioid malignant pleural mesothelioma (eMPM) patients undergoing palliative systemic therapy

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Background: Palliative chemotherapy, the mainstay for incurable eMPM, is offered to patients with good standing performance status (ECOG 0-1). We determined the proportion of eMPM patients experiencing moderate (Mod) to severe (Sev) symptoms while on palliative chemotherapy using ESAS symptom scores at diagnosis and during first and subsequent lines of systemic therapy. Methods: ESAS scores (0=no symptom; 10=worst symptom) were routinely captured in eMPM patients at Princess Margaret (Toronto, Canada). Retrospective chart review collected ESAS, clinical, treatment and outcome data. ESAS scores and proportions were summarized within baseline, firstline, and subsequent lines of therapy. Mod symptom was defined as ESAS scores of 4-6, and Sev as 7-10. ESAS scores between treatment lines were analyzed by Mann-Whitney U tests. Locally weighted smoothing (LOESS) plots assessed ESAS scores over treatment duration. Results: Of 37 palliative eMPM patients, the most frequent baseline symptoms were fatigue (33% Mod, 25% Sev), dyspnea (27% Mod; 17% Sev), anxiety (21% Mod; 21% Sev) and depression (34% Mod; 4% Sev). Overall well-being was poor in 45% of patients (31% Mod; 14% Sev). Compared to baseline, patients on firstline therapy reported increased pain ( p = 0.002), poor appetite ( p = 0.005) and nausea ( p = 0.02); decreased depression ( p = 0.03) and anxiety ( p = 0.006); and stable well-being ( p = 0.27). In patients well enough for subsequent therapy, patients reported reduced drowsiness ( p = 0.01) and improved overall well-being ( p = 0.04) compared to firstline therapy. LOESS plot patterns were similar between firstline and subsequent lines of treatment. Conclusions: eMPM patients had high symptom scores at the time of diagnosis. However, patients’ depression and anxiety decreased when starting initial treatment, and general well-being was stable. Of patients fit enough for subsequent lines of therapy, there were improvements in drowsiness and overall well-being. When selectively used, palliative systemic therapy of all lines are associated with some improved symptoms, but pain, poor appetite, and nausea need to be monitored and managed more effectively.

Mesothelioma: Scientific clues for prevention, diagnosis, and therapy

Mesothelioma affects mostly older individuals who have been occupationally exposed to asbestos. The global mesothelioma incidence and mortality rates are unknown, because data are not available from developing countries that continue to use large amounts of asbestos. The incidence rate of mesothelioma has decreased in Australia, the United States, and Western Europe, where the use of asbestos was banned or strictly regulated in the 1970s and 1980s, demonstrating the value of these preventive measures. However, in these same countries, the overall number of deaths from mesothelioma has not decreased as the size of the population and the percentage of old people have increased. Moreover, hotspots of mesothelioma may occur when carcinogenic fibers that are present in the environment are disturbed as rural areas are being developed. Novel immunohistochemical and molecular markers have improved the accuracy of diagnosis; however, about 14% (high-resource countries) to 50% (developing countries) of mesothelioma diagnoses are incorrect, resulting in inadequate treatment and complicating epidemiological studies. The discovery that germline BRCA1-asssociated protein 1 (BAP1) mutations cause mesothelioma and other cancers (BAP1 cancer syndrome) elucidated some of the key pathogenic mechanisms, and treatments targeting these molecular mechanisms and/or modulating the immune response are being tested. The role of surgery in pleural mesothelioma is controversial as it is difficult to predict who will benefit from aggressive management, even when local therapies are added to existing or novel systemic treatments. Treatment outcomes are improving, however, for peritoneal mesothelioma. Multidisciplinary international collaboration will be necessary to improve prevention, early detection, and treatment.

Scientific Advances and New Frontiers in Mesothelioma Therapeutics

Malignant pleural mesothelioma (MPM) is a rare and aggressive cancer that arises from the mesothelial surface of the pleural and peritoneal cavities, the pericardium, and rarely, the tunica vaginalis. The incidence of MPM is expected to increase worldwide in the next two decades. However, even with the use of multimodality treatment, MPM remains challenging to treat, with a 5-year survival rate of less than 5%. The International Association for the Study of Lung Cancer has gathered experts in different areas of mesothelioma research and management to summarize the most significant scientific advances and new frontiers related to mesothelioma therapeutics.

Radiologic Considerations and Standardization of Malignant Pleural Mesothelioma Imaging Within Clinical Trials: Consensus Statement from the NCI Thoracic Malignancy Steering Committee - International Association for the Study of Lung Cancer - Mesothelioma Applied Research Foundation Clinical Trials Planning Meeting

Detailed guidelines pertaining to radiological assessment of malignant pleural mesothelioma are currently lacking due to the rarity of the disease, complex morphology, propensity to invade multiple planes simultaneously, and lack of specific recommendations within the radiology community about assessment, reporting, and follow-up. In March 2017, a multidisciplinary meeting of mesothelioma experts was co-sponsored by the National Cancer Institute Thoracic Malignancy Steering Committee, International Association for the Study of Lung Cancer, and the Mesothelioma Applied Research Foundation. One of the outcomes of this conference was the foundation of detailed, multidisciplinary consensus imaging and management guidelines. Here, we present the recommendations for radiologic assessment of malignant pleural mesothelioma in the setting of clinical trial enrollment. We discuss optimization of imaging parameters across modalities, standardized reporting, and response assessment within clinical trials.

Association of two BRM promoter polymorphisms and smoking status with malignant pleural mesothelioma risk and prognosis

Brahma (BRM), of the SWI/SNF complex, has two 6 to 7 bp insertion promoter polymorphisms (BRM-741/BRM-1321) that cause epigenetic BRM suppression, and are associated with risk of multiple cancers. BRM polymorphisms were genotyped in malignant pleural mesothelioma (MPM) cases and asbestos-exposed controls. Multivariable logistic regression (risk) and Cox regression (prognosis) were performed, including stratified analyses by smoking status to investigate the effect of polymorphisms on MPM risk and prognosis. Although there was no significant association overall between BRM-741/BRM-1321 and risk in patients with MPM, a differential effect by smoking status was observed (P-interaction < .001), where homozygous variants were protective (aOR of 0.18-0.28) in ever smokers, while never smokers had increased risk when carrying homozygous variants (aOR of 2.7-4.4). While there was no association between BRM polymorphisms and OS in ever-smokers, the aHR of carrying homozygous-variants of BRM-741, BRM-1321 or both were 4.0 to 8.6 in never-smokers when compared to wild-type carriers. Mechanistically, lower mRNA expression of BRM was associated with poorer general cancer prognosis. Electrophoretic mobility shift assays and chromatin immunoprecipitation experiments (ChIP) revealed high BRM insertion variant homology to MEF2 regulatory binding sites. ChIP experimentation confirmed MEF2 binding only occurs in the presence of insertion variants. DNA-affinity purification assays revealed YWHA scaffold proteins as vital to BRM mRNA expression. Never-smokers who carry BRM homozygous variants have an increased chance of developing MPM, which results in worse prognosis. In contrast, in ever-smokers, there may be a protective effect, with no difference in overall survival. Mechanisms for the interaction between BRM and smoking require further study.

The Use of Radiation Therapy for the Treatment of Malignant Pleural Mesothelioma: Expert Opinion from the National Cancer Institute Thoracic Malignancy Steering Committee, International Association for the Study of Lung Cancer, and Mesothelioma Applied Research Foundation

INTRODUCTION

Detailed guidelines regarding the use of radiation therapy for malignant pleural mesothelioma (MPM) are currently lacking because of the rarity of the disease, the wide spectrum of clinical presentations, and the paucity of high-level data on individual treatment approaches.

METHODS

In March 2017, a multidisciplinary meeting of mesothelioma experts was cosponsored by the U.S. National Cancer Institute, International Association for the Study of Lung Cancer Research, and Mesothelioma Applied Research Foundation. Among the outcomes of this conference was the foundation of detailed, multidisciplinary consensus guidelines.

RESULTS

Here we present consensus recommendations on the use of radiation therapy for MPM in three discrete scenarios: (1) hemithoracic radiation therapy to be used before or after extrapleural pneumonectomy; (2) hemithoracic radiation to be used as an adjuvant to lung-sparing procedures (i.e., without pneumonectomy); and (3) palliative radiation therapy for focal symptoms caused by the disease. We discuss appropriate simulation techniques, treatment volumes, dose fractionation regimens, and normal tissue constraints. We also assess the role of particle beam therapy, specifically, proton beam therapy, for MPM.

CONCLUSION

The recommendations provided in this consensus statement should serve as important guidelines for developing future clinical trials of treatment approaches for MPM.