Modeling of mesothelioma growth demonstrates weaknesses of current response criteria

Imaging in pleural Mesothelioma: A review of the 16th International Conference of the International Mesothelioma Interest Group

Imaging continues to gain a greater role in the assessment and clinical management of patients with mesothelioma. This communication summarizes the oral presentations from the imaging session at the 2023 International Conference of the International Mesothelioma Interest Group (iMig), which was held in Lille, France from June 26 to 28, 2023. Topics at this session included an overview of best practices for clinical imaging of mesothelioma as reported by an iMig consensus panel, emerging imaging techniques for surgical planning, radiologic assessment of malignant pleural effusion, a radiomics-based transfer learning model to predict patient response to treatment, automated assessment of early contrast enhancement, and tumor thickness for response assessment in peritoneal mesothelioma.

Fully automated volumetric measurement of malignant pleural mesothelioma by deep learning AI: validation and comparison with modified RECIST response criteria

BACKGROUND

In malignant pleural mesothelioma (MPM), complex tumour morphology results in inconsistent radiological response assessment. Promising volumetric methods require automation to be practical. We developed a fully automated Convolutional Neural Network (CNN) for this purpose, performed blinded validation and compared CNN and human response classification and survival prediction in patients treated with chemotherapy.

METHODS

In a multicentre retrospective cohort study; 183 CT datasets were split into training and internal validation (123 datasets (80 fully annotated); 108 patients; 1 centre) and external validation (60 datasets (all fully annotated); 30 patients; 3 centres). Detailed manual annotations were used to train the CNN, which used two-dimensional U-Net architecture. CNN performance was evaluated using correlation, Bland-Altman and Dice agreement. Volumetric response/progression were defined as ≤30%/≥20% change and compared with modified Response Evaluation Criteria In Solid Tumours (mRECIST) by Cohen's kappa. Survival was assessed using Kaplan-Meier methodology.

RESULTS

Human and artificial intelligence (AI) volumes were strongly correlated (validation set r=0.851, p<0.0001). Agreement was strong (validation set mean bias +31 cm3 (p=0.182), 95% limits 345 to +407 cm3). Infrequent AI segmentation errors (4/60 validation cases) were associated with fissural tumour, contralateral pleural thickening and adjacent atelectasis. Human and AI volumetric responses agreed in 20/30 (67%) validation cases κ=0.439 (0.178 to 0.700). AI and mRECIST agreed in 16/30 (55%) validation cases κ=0.284 (0.026 to 0.543). Higher baseline tumour volume was associated with shorter survival.

CONCLUSION

We have developed and validated the first fully automated CNN for volumetric MPM segmentation. CNN performance may be further improved by enriching future training sets with morphologically challenging features. Volumetric response thresholds require further calibration in future studies.

Protocol for a prospective observational cohort study collecting data on demographics, symptoms and biomarkers in people with mesothelioma (ASSESS-meso)

INTRODUCTION

Mesothelioma is a heterogeneous disease that can be challenging to monitor and prognosticate. ASSESS-meso is a multicentre, prospective, longitudinal observational cohort study of patients with mesothelioma. The primary aim is to describe different clinical phenotypes and investigate predictive and prognostic factors, including biomarkers from blood and pleural fluid. The secondary aim is to provide a resource for future trials and substudies.

METHODS AND ANALYSIS

We aim to recruit 700 patients with a histological, cytological or clinicopathological diagnosis of mesothelioma, at any anatomical site (pleural, peritoneal, pericardial, etc). Longitudinal data will be collected, including clinical information, radiological investigations, blood tests and patient-reported outcome measures for breathlessness, chest pain and sweats. Preplanned analyses will use Cox proportional hazards method to evaluate factors associated with survival, linear and logistic regression models to investigate associations with symptoms, and analysis of variance modelling to explore changes in symptoms over time.

ETHICS AND DISSEMINATION

Ethical approval has been granted by the Research Ethics Committee South West-Central Bristol (17-SW-0019) and Health Research Authority (IRAS ID 220360). A study steering committee has been established and results will be published OpenAccess in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ISRCTN: 61861764.

Retrospective Study of Clinical Outcomes and Toxicity Profile in Patients Treated with Immune Checkpoint Inhibitors

Introduction Immune checkpoint inhibitors (ICIs) are rapidly being utilized as treatment option either alone or in combination with chemotherapy in most of the solid tumors.

Objectives Our single-center retrospective study aimed to present our experience with the effectiveness and safety of these agents in Indian set of patients with various advanced solid tumors.

Material and Methods Twenty-five adult patients with stage IV solid tumors of varying sites treated with ICIs at Aditya Birla Memorial Hospital, Pune, Maharashtra, India, between October 2017 and September 2020 were included in the study. Overall survival (OS), progression-free survival (PFS), overall response rate (ORR), disease control rate (DCR), and toxicity profiles were evaluated. All statistical calculations were performed using IBM SPSS version 25.

Results Total of 25 patients (median age 61) was evaluated. Histological evaluation revealed adenocarcinoma (48%), squamous cell carcinoma (40%), and one each (4%) of others. Eastern Cooperative Oncology Group performance status score was I in 16 (64%) and II in 9 (36%) patients. Average of 10 cycles ICIs were received by each patient. Majority were males with 11 (44%) having some comorbidities. Lung (48%) was the most common primary followed by head and neck cancers (32%). Most (76%) were treated with nivolumab, followed by pembrolizumab (20%) while only one patient was given atezolizumab. Median follow-up was 18 months. Median OS was 24 months (95% confidence interval [CI]: 9–NA) and 2-year OS rate in the study was 38.4% (95% CI: 18.8–78.3), while median PFS was 9 months (95% CI: 6–NA) and 1-year PFS rate was 22.3% (95% CI: 9.7–51.2). One patient (4%) had complete response, 6 (24%) had partial response while 12 (48%) had stable disease response at first follow-up. Mean and median time to progression were 5.7 and 9 months, respectively. ORR was 28% (95% CI: 12.07–49.4) while the DCR was 76% (95% CI: 54.87–90.64). PS II patients were associated with significantly poor median OS and PFS. There was no significant difference in survival with respect to age, gender, site, histology, and comorbidities; however, 4/25 patients had undergone biomarker assessment and were associated with a trend toward better median PFS (8 vs. 11 months, hazard ratio 0.53, 95% CI: 0.12–2.34, p = 0.38). Two of 25 patients developed autoimmune conditions namely ophthalmoplegia and hypothyroidism each. Fatigue (36%) and nausea (12%) were the most common toxicities.

Conclusion Real-world data from our study depicts our own experience with ICIs to suggest that these agents are well-tolerated and equally effective in Indian set of patients with advanced metastatic solid tumors. ICIs could be safely used even in patients with PS II and biomarker assessment in adjunction needs to be encouraged wherever feasible for better patient selection, prognostication, and clinical outcomes.

Deep learning-based segmentation of malignant pleural mesothelioma tumor on computed tomography scans: application to scans demonstrating pleural effusion

Tumor volume is a topic of interest for the prognostic assessment, treatment response evaluation, and staging of malignant pleural mesothelioma. Many mesothelioma patients present with, or develop, pleural fluid, which may complicate the segmentation of this disease. Deep convolutional neural networks (CNNs) of the two-dimensional U-Net architecture were trained for segmentation of tumor in the left and right hemithoraces, with the networks initialized through layers pretrained on ImageNet. Networks were trained on a dataset of 5230 axial sections from 154 CT scans of 126 mesothelioma patients. A test set of 94 CT sections from 34 patients, who all presented with both tumor and pleural effusion, in addition to a more general test set of 130 CT sections from 43 patients, were used to evaluate segmentation performance of the deep CNNs. The Dice similarity coefficient (DSC), average Hausdorff distance, and bias in predicted tumor area were calculated through comparisons with radiologist-provided tumor segmentations on the test sets. The present method achieved a median DSC of 0.690 on the tumor and effusion test set and achieved significantly higher performance on both test sets when compared with a previous deep learning-based segmentation method for mesothelioma.

Deep convolutional neural networks for the automated segmentation of malignant pleural mesothelioma on computed tomography scans

Tumor volume has been a topic of interest in the staging, prognostic evaluation, and treatment response assessment of malignant pleural mesothelioma (MPM). Deep convolutional neural networks (CNNs) were trained separately for the left and right hemithoraces on the task of differentiating between pleural thickening and normal thoracic tissue on computed tomography (CT) scans. A total of 4259 and 6192 axial sections containing segmented tumor were used to train the left-hemithorax CNN and the right-hemithorax CNN, respectively. Two distinct test sets of 131 sections from the CT scans of 43 patients were used to evaluate segmentation performance by calculating the Dice similarity coefficient (DSC) between deep CNN-generated tumor segmentations and reference tumor segmentations provided by a total of eight observers. Median DSC values ranged from 0.662 to 0.800 over the two test sets when comparing deep CNN-generated segmentations with observer reference segmentations. The deep CNN-based method achieved significantly higher DSC values for all three observers on the test set that allowed direct comparisons with a previously published automated segmentation method of MPM tumor on CT scans ( p < 0.0005 ). A deep CNN was implemented for the automated segmentation of MPM tumor on CT scans, showing superior performance to a previously published method.

Treatment of Malignant Pleural Mesothelioma: American Society of Clinical Oncology Clinical Practice Guideline

Purpose To provide evidence-based recommendations to practicing physicians and others on the management of malignant pleural mesothelioma. Methods ASCO convened an Expert Panel of medical oncology, thoracic surgery, radiation oncology, pulmonary, pathology, imaging, and advocacy experts to conduct a literature search, which included systematic reviews, meta-analyses, randomized controlled trials, and prospective and retrospective comparative observational studies published from 1990 through 2017. Outcomes of interest included survival, disease-free or recurrence-free survival, and quality of life. Expert Panel members used available evidence and informal consensus to develop evidence-based guideline recommendations. Results The literature search identified 222 relevant studies to inform the evidence base for this guideline. Recommendations Evidence-based recommendations were developed for diagnosis, staging, chemotherapy, surgical cytoreduction, radiation therapy, and multimodality therapy in patients with malignant pleural mesothelioma. Additional information is available at www.asco.org/thoracic-cancer-guidelines and www.asco.org/guidelineswiki .

Prognostic and predictive role of [18 F]fluorodeoxyglucose positron emission tomography (FDG-PET) in patients with unresectable malignant pleural mesothelioma (MPM) treated with up-front pemetrexed-based chemotherapy

The aim of this study was to evaluate the role of metabolic parameters analyzed at baseline and at interim FDG‐PET in predicting disease outcome in unresectable MPM patients receiving pemetrexed‐based chemotherapy. A consecutive series of MPM patients treated between February 2004 and July 2013 with first‐line pemetrexed‐based chemotherapy, and evaluated by FDG‐PET and CT scan at baseline and after two cycles of chemotherapy, was reviewed. Best CT scan response was assessed according to modified RECIST criteria. Progression‐free survival (PFS) and overall survival (OS) were correlated with FDG‐PET parameters, such as maximum standardized uptake value (SUV_max), total lesion glycolysis (TLG), and percentage changes in SUV_max (∆SUV) and TLG (∆TLG). Overall, 142 patients were enrolled; 77 (54%) received talc pleurodesis before chemotherapy. Baseline SUV_max and TLG showed a statistically significant correlation with PFS and OS (P < 0.05) in both group of patients (treated and untreated with pleurodesis). In 65 patients not receiving pleurodesis, SUV_max reduction ≥25% (∆SUV ≥ 25%) and TLG reduction ≥30% (∆TLG ≥ 30%) were significantly associated with longer PFS (P < 0.05). Patients showing both ∆SUV ≥ 25% and ∆TLG ≥ 30% responses had a significant reduction in the risk of disease progression (HR:0.31, P < 0.001) and death (HR:0.52, P = 0.044). Neither ∆SUV nor ∆TLG showed similar association with survival outcomes in patients treated with pleurodesis. Our study confirmed the prognostic role of baseline FDG‐PET in a large series of MPM patients treated with first‐line pemetrexed‐based chemotherapy. Moreover, use of ∆SUV ≥ 25% and ∆TLG ≥ 30% as cut‐off values to define early metabolic response supported the role of FDG‐PET in predicting disease outcome and treatment response in patients not receiving pleurodesis.

Malignant pleural mesothelioma segmentation for photodynamic therapy planning

Medical imaging modalities such as computed tomography (CT) combined with computer-aided diagnostic processing have already become important part of clinical routine specially for pleural diseases. The segmentation of the thoracic cavity represents an extremely important task in medical imaging for different reasons. Multiple features can be extracted by analyzing the thoracic cavity space and these features are signs of pleural diseases including the malignant pleural mesothelioma (MPM) which is the main focus of our research. This paper presents a method that detects the MPM in the thoracic cavity and plans the photodynamic therapy in the preoperative phase. This is achieved by using a texture analysis of the MPM region combined with a thoracic cavity segmentation method. The algorithm to segment the thoracic cavity consists of multiple stages. First, the rib cage structure is segmented using various image processing techniques. We used the segmented rib cage to detect feature points which represent the thoracic cavity boundaries. Next, the proposed method segments the structures of the inner thoracic cage and fits 2D closed curves to the detected pleural cavity features in each slice. The missing bone structures are interpolated using a prior knowledge from manual segmentation performed by an expert. Next, the tumor region is segmented inside the thoracic cavity using a texture analysis approach. Finally, the contact surface between the tumor region and the thoracic cavity curves is reconstructed in order to plan the photodynamic therapy. Using the adjusted output of the thoracic cavity segmentation method and the MPM segmentation method, we evaluated the contact surface generated from these two steps by comparing it to the ground truth. For this evaluation, we used 10 CT scans with pathologically confirmed MPM at stages 1 and 2. We obtained a high similarity rate between the manually planned surface and our proposed method. The average value of Jaccard index was about 0.79 and we obtained a value of 0.88 using the Dice index.

First-line chemotherapy with pemetrexed plus cisplatin for malignant peritoneal mesothelioma

BACKGROUND

Mesothelioma of peritoneal origin has wider variation in treatment outcomes than mesothelioma of pleural origin, likely because peritoneal mesothelioma comprises borderline malignant variants and aggressive malignant peritoneal mesothelioma (MPeM). This study retrospectively evaluates the efficacy of first-line systemic pemetrexed and cisplatin chemotherapy in MPeM.

RESEARCH DESIGN AND METHODS

Twenty-four patients with histologically proven MPeM were treated with pemetrexed plus cisplatin as a first-line systemic chemotherapy. The response was evaluated radiologically according to standard Response Evaluation Criteria In Solid Tumors (RECIST) criteria. Twenty-two patients underwent ¹⁸F-fluorodeoxyglucose positron emission tomography/(FDG-PET)/computed tomography(CT) at baseline, and 13 were eligible for metabolic assessment.

RESULTS

Two complete responses and 9 partial responses were achieved. Overall response rate and disease control rate were 45.8% and 91.7%, respectively. Median progression-free survival and median overall survival were 11.0 months and 15.8 months, respectively. Wet- type MPeM had significantly longer survival (40.9 months median) than other clinical types (15.5 months) (P = 0.045). The baseline maximum standardized uptake value in 22 patients was 8.93 (range, 2.5-16.77).

CONCLUSIONS

Systemic pemetrexed plus cisplatin is active for MPeM. Disparity with the outcome of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) needs to receive more emphasis, since peritoneal mesothelioma has a 5-year survival rate of 50%.

Computer-aided volumetric assessment of malignant pleural mesothelioma on CT using a random walk-based method

OBJECTIVE

The aim of this study is to assess the performance of a computer-aided semi-automated algorithm we have adapted for the purpose of segmenting malignant pleural mesothelioma (MPM) on CT.

METHODS

Forty-five CT scans were collected from 15 patients (M:F [Formula: see text] 10:5, mean age 62.8 years) in a multi-centre clinical drug trial. A computer-aided random walk-based algorithm was applied to segment the tumour; the results were then compared to radiologist-drawn contours and correlated with measurements made using the MPM-adapted Response Evaluation Criteria in Solid Tumour (modified RECIST).

RESULTS

A mean accuracy (Sørensen-Dice index) of 0.825 (95% CI [0.758, 0.892]) was achieved. Compared to a median measurement time of 68.1 min (range [40.2, 102.4]) for manual delineation, the median running time of our algorithm was 23.1 min (range [10.9, 37.0]). A linear correlation (Pearson's correlation coefficient: 0.6392, [Formula: see text]) was established between the changes in modified RECIST and computed tumour volume.

CONCLUSION

Volumetric tumour segmentation offers a potential solution to the challenges in quantifying MPM. Computer-assisted methods such as the one presented in this study facilitate this in an accurate and time-efficient manner and provide additional morphological information about the tumour's evolution over time.

Metabolic response assessment with 18F-FDG-PET/CT is superior to modified RECIST for the evaluation of response to platinum-based doublet chemotherapy in malignant pleural mesothelioma

PURPOSE

Efficient monitoring of tumor responsiveness to chemotherapy is essential to mitigate high mortality risks and cytotoxic effects of chemotherapeutics. However, there is no consensus on the most suitable diagnostic technique/parameters for assessing response to chemotherapy in malignant pleural mesothelioma (MPM). We compared the tumor responsiveness of MPM patients as assessed using modified RECIST (mRECIST) criteria and integrated 18F-FDG-PET/CT.

METHODS

Histologically confirmed MPM patients (N=82) who were treated with three cycles of cisplatin and pemetrexed, or carboplatin and pemetrexed, were included. mRECIST and integrated 18F-FDG-PET/CT were used to evaluate MPM tumor response to chemotherapy. Metabolic non-responders were defined as those with a 25% or greater increase in SUVmax compared with the previous value. Time to progression (TTP) and overall survival (OS) were compared between metabolic-responders and non-responders.

RESULTS

After three cycles of chemotherapy, 62(75.6%) of the patients were classified as having SD, 15 (18%) with partial remission (PR), and 5 (6%) with progressive disease (PD), based on mRECIST criteria. The cumulative median OS was 728.0days (95% confidence interval [CI]: 545.9-910.1) and cumulative median TTP was 365.0days (95% CI: 296.9-433.1). For the 82 patients, the disease control rate was 93.9%, whereas the metabolic response rate was only 71.9% (p<0.001). All PD and PR patients were found to be metabolic responders on 18F-FDG-PET/CT; however, among the 62mRECIST SD patients, 18 (29%) were classified as metabolic non-responders. The median TTP for metabolic responders was 13.7 months, while it was 10.0 months for non-responders(p<0.001). Metabolic responders had a trend toward longer OS, although the difference did not reach statistical significance (metabolic responders:33.9 months; non-responders: 21.6 months; p>0.05).

CONCLUSION

Several mRECIST-confirmed SD MPM patients may be classified as metabolic non-responders on18F-FDGPET/CT. Metabolic response is significantly correlated with the median TTP, suggesting it should be included in the evaluation of the response to chemotherapy in MPM patients classified as mRECIST SD, to identify non-responders.

Imaging in pleural mesothelioma: A review of the 13th International Conference of the International Mesothelioma Interest Group

Imaging plays an important role in the detection, diagnosis, staging, response assessment, and surveillance of malignant pleural mesothelioma. The etiology, biology, and growth pattern of mesothelioma present unique challenges for each modality used to capture various aspects of this disease. Clinical implementation of imaging techniques and information derived from images continue to evolve based on active research in this field worldwide. This paper summarizes the imaging-based research presented orally at the 2016 International Conference of the International Mesothelioma Interest Group (iMig) in Birmingham, United Kingdom, held May 1-4, 2016. Presented topics included intraoperative near-infrared imaging of mesothelioma to aid the assessment of resection completeness, an evaluation of tumor enhancement improvement with increased time delay between contrast injection and image acquisition in standard clinical magnetic resonance imaging (MRI) scans, the potential of early contrast enhancement analysis to provide MRI with a role in mesothelioma detection, the differentiation of short- and long-term survivors based on MRI tumor volume and histogram analysis, the response-assessment potential of hemodynamic parameters derived from dynamic contrast-enhanced computed tomography (DCE-CT) scans, the correlation of CT-based tumor volume with post-surgical tumor specimen weight, and consideration of the need to update the mesothelioma tumor response assessment paradigm.

Induction Therapy for Mesothelioma

One particular approach of multimodality treatment for mesothelioma is induction therapy followed by surgery. Among its several advantages, the most important is downstaging of the tumor into a resectable stage, although morbidity and mortality might be increased. In this article we review the principles and outcome of different modalities for induction treatment of mesothelioma.

Response evaluation in mesothelioma: Beyond RECIST

Malignant pleural mesothelioma (MPM) typically demonstrates a non-spherical growth pattern, so it is often difficult to accurately categorize change in tumour burden using size-based tumour response criteria (e.g., WHO (World Health Organisation), RECIST (Response Evaluation Criteria in Solid Tumours) and modified RECIST). Functional imaging techniques are applied to derive quantitative measurements of tumours, which reflect particular aspects of the tumour pathophysiology. By quantifying how these measurements change with treatment, it is possible to observe treatment effects. In this review, we survey the existing roles of CT and MRI for the management of MPM, including the currently applied size measurement criteria for the assessment of treatment response. New functional imaging techniques, such as positron emission tomography (PET), diffusion-weighted MRI (DWI) and dynamic contrast-enhanced MRI (DCE-MRI) that may potentially improve the assessment of treatment response will be highlighted and discussed.

Management of malignant pleural mesothelioma-The European experience

Management of malignant pleural mesothelioma (MPM) remains a clinical challenge and the incidence of the disease will continue to increase worldwide. Several aspects of mesothelioma treatment are discussed controversially, in particular, regarding extent and best type of surgery, radiotherapy, and the role of neoadjuvant or adjuvant treatment. However, best survival data is reported from groups using multimodality treatment including macroscopic complete resection (MCR) achieved by either extrapleural pneumonectomy (EPP) or (extended) pleurectomy/decortication for patients qualifying from the tumor biology, stage, and patient's performance status and comorbidities. Several aspects have to be considered during surgery but morbidity and mortality have been reduced at experienced centres. The final analysis of extended selection algorithms is pending.

Manual contouring based volumetric evaluation for colorectal cancer with liver limited metastases: a comparison with RECIST

BACKGROUND

To compare response evaluation criteria in solid tumours (RECIST) and volumetric evaluation (VE) for colorectal cancer with liver-limited metastasis.

PATIENTS AND METHODS

VE of liver metastases was performed by manual contouring before and after chemotherapy on 45 pairs of computed tomography (CT) images in 36 patients who suffered from metastatic colorectal cancer (mCRC) with liver metastasis only. Cohen kappa was used to compare the agreement between VE and RECIST. Pearson correlation was performed for their comparison after cubic root transformation of the aggregate tumor volumes. Logistic regression was done to identify clinical and radiographic factors to account for the difference which may be predictive in overall response (OR).

RESULTS

There were 16 partial response (PR), 23 stable disease (SD) and 6 progressive disease (PD) cases with VE, and 14 PR, 23 SD and 8 PD with RECIST. VE demonstrated good agreement with RECIST (κ=0.779). Discordant objective responses were noted in 6 pairs of comparisons (13.3%). Pearson correlation also showed excellent correlation between VE and RECIST (r2=0.966, p<0.001). Subgroup analysis showed that VE was in slightly better agreement with RECIST for enlarging lesions than for shrinking lesions (r2=0.935 and r2=0.780 respectively). No factor was found predictive of the difference in OR between VE and RECIST.

CONCLUSIONS

VE exhibited good agreement with RECIST. It might be more useful than RECIST in evaluation shrinking lesions in cases of numerous and conglomerate liver metastases.

Lung volume measurements as a surrogate marker for patient response in malignant pleural mesothelioma

INTRODUCTION

The purpose of this study was to investigate the continuous changes in three distinct response assessment methods during treatment as a marker of response for patients with mesothelioma. Linear tumor thickness measurements, disease volume measurements, and lung volume measurements (a physiological correlate of disease volumes) were investigated in this study.

METHODS

Serial computed tomography scans were obtained during the course of clinically standard chemotherapy for 61 patients. For each of the 216 computed tomography scans, the aerated lung volumes were segmented using a fully automated method, and the pleural disease volume was segmented using a semiautomated method. Modified Response Evaluation Criteria in Solid Tumors linear-thickness measurements were acquired clinically. Diseased (ipsilateral) lung volumes were normalized by the respective contralateral lung volumes to account for the differences in inspiration between scans for each patient. Relative changes in each metric from baseline were tracked over the course of follow-up imaging. Survival modeling was performed using Cox proportional hazards models with time-varying covariates.

RESULTS

Median survival from pretreatment baseline imaging was 12.7 months. A negative correlation was observed between measurements of lung volume and disease volume, and a positive correlation was observed between linear-thickness measurements and disease volume. As continuous numerical parameters, all three response assessment methods were significant imaging biomarkers of patient prognosis in independent survival models.

CONCLUSIONS

Analysis of trajectories of linear-thickness measurements, disease volume measurements, and lung volume measurements during chemotherapy for patients with mesothelioma indicates that increasing linear thickness, increasing disease volume, and decreasing lung volume are all significantly and independently associated with poor patient prognosis.

Optimization of response classification criteria for patients with malignant pleural mesothelioma

INTRODUCTION

Response-assessment metrics play an important role in clinical trials and routine patient management. For patients with malignant pleural mesothelioma (MPM), the standard for response assessment is image-based measurements of tumor thickness made according to the modified RECIST (Response Evaluation Criteria in Solid Tumors) protocol. To classify tumor response, changes in tumor thickness are compared with the standard RECIST -30% and +20% cutoffs for partial response (PR) and progressive disease (PD), respectively, which are not specific to MPM. The purpose of this work is to optimize the correlation between tumor response and patient survival by assessing the validity of existing response criteria in MPM and proposing alternative criteria.

METHODS

Computed tomography measurements of tumor thickness were acquired at baseline and throughout treatment for 78 patients undergoing standard-of-care chemotherapy. Overall survival was correlated with best response and first follow-up response using Harrell's C statistic. The response criteria for PD and PR were each varied in 1% increments to obtain optimized classification criteria. The performance was cross-validated using a leave-one-out approach.

RESULTS

Median survival was 14.9 months. The performance of the standard RECIST criteria in correlating response with survival was C=0.778, whereas the optimized performance of C=0.855 was obtained with criteria of -64% for PR and +50% for PD. After cross-validation, this performance was slightly reduced to C=0.829.

CONCLUSIONS

Optimized tumor-response classification criteria were obtained for patients with MPM. These criteria improve the correlation between image-based response and patient survival.

Changes in pulmonary function tests predict radiological response to chemotherapy in malignant pleural mesothelioma

OBJECTIVES

Response to chemotherapy in malignant pleural mesothelioma (MPM) is usually evaluated by radiological criteria, but no common agreement exists on their validity, yet. The cytoreductive effect of chemotherapy on pleural thickening may make the lung more expansible, reducing the restrictive ventilatory impairment. The aim of this study was to evaluate the changes in pulmonary function following chemotherapy in patients with MPM and to correlate these findings with radiological changes.

METHODS

Between 2004 and 2011, 62 consecutive patients (74% males, median age 63 years) were prospectively investigated. Modified RECIST criteria were used for radiological evaluation of response to chemotherapy. All patients underwent pulmonary function tests before and after three cycles of platinum-based chemotherapy. Changes between baseline and post-chemotherapy pulmonary function values (Δ) and their differences were assessed by means of Student's paired and unpaired t-test, respectively. Receiver operating characteristic (ROC) curve analysis was performed on spirometric parameters significantly associated with response.

RESULTS

Thirty (48.4%) patients had a radiological stable disease (S), 23 (37.1%) a partial response (R) and 9 (14.5%) a progressive disease (P). ΔFEV1%pred (R: 18.1 ± 18.5%; S: 0.5 ± 9.3%; P: -11 ± 13.5%; P < 0.0001), ΔFVC%pred (R: 16.1 ± 11.8%; S: 0.4 ± 11.2%; P: -9.2 ± 14.6%; P < 0.0001) and ΔVC%pred (R: 12.9 ± 15.7%; S: 1.5 ± 12.1%; P: -6.1 ± 13.2%; P = 0.001) were significantly associated with radiological response. A significant correlation was observed between ΔFEV1%pred (r = 0.46, P = 0.01), ΔFVC%pred (r = 0.43, P = 0.02) and % change in linear tumour measurement. ROC curve analysis using dichotomized radiological response (P/S vs R) as classification variables showed AUC = 0.88 (95%CI: 0.77-0.95) for ΔFEV1%pred (optimal cut-off value: +7%, sensitivity: 83%, specificity: 82%, PPV: 73%, NPV: 89%) and AUC = 0.86 (95%CI: 0.75-0.94) for ΔFVC%pred (optimal cut-off value: +6%, sensitivity: 82%, specificity: 74%, PPV: 64%, NPV: 88%).

CONCLUSIONS

Dynamic lung volumes and radiological changes after chemotherapy seem directly related. Lung function changes could be an additional tool to better evaluate the response to chemotherapy in MPM.

Disease volumes as a marker for patient response in malignant pleural mesothelioma

BACKGROUND

The goal of this study was to create a comprehensive model for malignant pleural mesothelioma patient survival utilizing continuous, time-varying estimates of disease volume from computed tomography (CT) imaging in conjunction with clinical covariates.

PATIENTS AND METHODS

Serial CT scans were obtained during the course of clinically standard chemotherapy for 81 patients. The pleural disease volume was segmented for each of the 281 CT scans, and relative changes in disease volume from the baseline scan were tracked over the course of serial follow-up imaging. A prognostic model was built using time-varying disease volume measurements in conjunction with clinical covariates.

RESULTS

Over the course of treatment, disease volume decreased by an average of 19%, and median patient survival was 12.6 months from baseline. In a multivariate survival model, changes in disease volume were significantly associated with patient survival along with disease histology, Eastern Cooperative Oncology Group performance status, and presence of dyspnea.

CONCLUSIONS

Analysis of the trajectories of disease volumes during chemotherapy for patients with mesothelioma indicates that increasing disease volume was significantly and independently associated with poor patient prognosis in both univariate and multivariate survival models.

A Multimodality Imaging Review of Malignant Pleural Mesothelioma Response Assessment

Assessment of response is important to interpret early phase clinical trial results and to guide individual patient management. In malignant pleural mesothelioma (MPM), the circumferential growth pattern of the disease, the presence of pleural effusion and atelectasis, and the common use of pleurodesis make this a challenging task for imaging specialists and clinicians. This article reviews the current evidence for radiological and positron emission tomography (PET) response assessment in MPM, and the pitfalls and challenges in its application. Current research and future directions in radiological and PET response are discussed, including the use of novel radiotracers.

Serum soluble mesothelin concentrations in malignant pleural mesothelioma: relationship to tumor volume, clinical stage and changes in tumor burden

PURPOSE

To examine the clinical utility of soluble mesothelin in patients with malignant pleural mesothelioma.

EXPERIMENTAL DESIGN

A total of 97 patients (female: 11; male: 86) were prospectively enrolled, longitudinal serum samples collected, and mesothelin concentrations determined. Baseline mesothelin levels were analyzed relative to tumor stage, presence of metastatic disease, the positron emission tomography (PET) parameters maximum standardized uptake value, tumor volume, total glycolytic volume, and survival. Changes in mesothelin level were correlated to objective response to chemotherapy, as assessed radiologically and by PET imaging, and with patient survival.

RESULTS

Baseline mesothelin levels greater than 5 nmol/L were a significant negative prognostic indicator (HR = 2.25; 95% CI, 1.20-4.21) and correlated with tumor stage and volume. In 55 patients who received chemotherapy, change in mesothelin correlated with radiological response (χ(2) = 11.32; P = 0.023) and change in metabolically active tumor volume (r = 0.58; P < 0.01). Median survival for patients with a reduction in mesothelin following chemotherapy (19 months) was significantly longer than for patients with increased mesothelin (5 months; P < 0.001).

CONCLUSION

These findings show the potential value of changes in mesothelin levels for prognostication and monitoring of treatment response in mesothelioma.

Assessment of therapy responses and prediction of survival in malignant pleural mesothelioma through computer-aided volumetric measurement on computed tomography scans

PURPOSE

The purposes of this study were (1) to calculate the tumor volume in patients with malignant pleural mesothelioma using computed tomography (CT) scan images and a computer-aided measurement technique and (2) to investigate whether the baseline volume, or volume change after chemotherapy, predicts patient survival.

METHODS

We compiled the clinical characteristics and outcome from 30 patients enrolled in two clinical trials at our cancer center in which the patients were treated with induction chemotherapy followed by surgery and radiation. CT scans of 30 patients were obtained at baseline and after two cycles of chemotherapy. Tumor volumes were calculated using a semiautomated computer algorithm. Overall survival was measured using a landmark time at 3 months post-treatment start date such that all patients had already received two cycles of chemotherapy and a follow-up scan. Association of volume changes with overall survival were determined by a Cox Proportional Hazards Model or log-rank test. The relationship between both pre and postoperative clinical stage and baseline tumor volume was analyzed using the rank sum test.

RESULTS

The median baseline tumor volume was 473 cm(3) (range, 61 cm(3)-2108 cm(3)). Patients with high preoperative stages (III and IV) had larger baseline tumor volume than those with low preoperative stages (I and II) (p = 0.05). Patients with baseline volumes smaller than 619 cm(3) tended to survive longer than those with baseline volumes larger than or equal to 619 cm(3) (p = 0.07). Percentage change of tumor volume from baseline to first follow-up CT after two cycles of chemotherapy was significantly associated with overall survival (hazard ratio: 1.94 [95% confidence interval, 1.05-3.60], p = 0.04). Whereas the relative change in modified RECIST measurements was not significantly associated with overall survival (hazard ratio: 1.06 [95% confidence interval, 0.96-1.16], p = 0.25). By classifying changes of tumor volumes between two scans into two groups, i.e., "increase" and "decrease," a significant difference in survival was found between those who increased and decreased after two cycles of chemotherapy (p = 0.03).

CONCLUSIONS

Changes in tumor volume after two cycles of chemotherapy predicted overall survival in patients with malignant pleural mesothelioma. Tumor volume at baseline was shown to be associated with preoperative clinical stage and survival. Computer-aided volumetric measurements may enable more reliable therapeutic response assessment and could provide additional prognostic information.

Phase II Study of Asparagine-Glycine-Arginine–Human Tumor Necrosis Factor α, a Selective Vascular Targeting Agent, in Previously Treated Patients With Malignant Pleural Mesothelioma

Purpose

NGR-hTNF consists of human tumor necrosis factor α (hTNF-α) fused to the tumor-homing peptide asparagine-glycine-arginine (NGR) able to selectively bind an aminopeptidase N isoform overexpressed on tumor blood vessels. Hypervascularity is a prominent and poor-prognosis feature of malignant pleural mesothelioma (MPM). Currently, there are no standard options for patients with MPM who are failing a front-line pemetrexed-based regimen. We explored safety and efficacy of NGR-hTNF in this setting.

Patients and Methods

Eligible patients had radiologically documented tumor progression and performance status ≤ 2. Primary study aim was progression-free survival (PFS). NGR-hTNF 0.8 μg/m2 was given intravenously every 3 weeks. A subsequent cohort of patients received 0.8 μg/m2 on a weekly basis.

Results

In the triweekly cohort (n = 43), only one grade 3 drug-related toxicity was noted, and the most common grades 1 to 2 were short-lived chills (71%). The median PFS was 2.8 months (95% CI, 2.3 to 3.3 months). Nineteen patients (44%) had disease control (one had partial response, and 18 had stable diseases) and experienced a median progression-free time of 4.4 months. In the weekly cohort (n = 14), there was no higher toxicity, and median PFS was 3.0 months (95% CI, 1.9 to 4.1 months). Seven patients (50%) had disease control (all stable diseases) and had a median progression-free interval of 9.1 months. In the overall study population (N = 57), median PFS was 2.8 months. Median progression-free time was 4.7 months in twenty-six patients (46%) who achieved disease control. Median survival was 12.1 months.

Conclusion

The tolerability and disease control of NGR-hTNF 0.8 μg/m2 weekly warrant additional evaluation in patients with advanced MPM.

Malignant pleural mesothelioma

Malignant pleural mesothelioma continues to be a challenge. The diagnosis and treatment of patients with malignant pleural mesothelioma requires a multidisciplinary approach. The diagnosis is best made by thoracoscopic biopsy and the aid of immunohistochemistry. Molecular studies identified inactivation of the neurofibromatosis-2 gene and INK4alpha/ARF to be key events in tumorigenesis. Based on the results of a Phase III trial, the combination of cisplatin with pemetrexed has become the preferred choice for chemotherapy, although there is suggestive evidence for the activity of other platin combinations based on Phase II studies. The optimal second-line chemotherapy remains to be defined. Surgical interventions ranging from pleurectomy/decortication to extrapleural pneumonectomy are increasingly offered in specialized centers, and the results of multimodality approaches with neoadjuvant or adjuvant chemotherapy and extrapleural pneumonectomy are encouraging. Ongoing investigations are defining the role of postoperative radiotherapy and the clinical activity of tyrosine kinase inhibitors targeting VEGFR2, histone deacetylase inhibitors and proteosome inhibitors.

Advances in the systemic therapy of malignant pleural mesothelioma

Malignant pleural mesothelioma is an aggressive thoracic malignancy associated with exposure to asbestos, and its incidence is anticipated to increase during the first half of this century. Chemotherapy is the mainstay of treatment, yet sufficiently robust evidence to substantiate the current standard of care has emerged only in the past 5 years. This Review summarizes the evidence supporting the clinical activity of chemotherapy, discusses the use of end points for its assessment and examines the influence of clinical and biochemical prognostic factors on the natural history of malignant pleural mesothelioma. Early-phase clinical trials of second-line and novel agents are emerging from an increased understanding of mesothelioma cell biology. Coupled with high-quality translational research, such developments have real potential to improve the outlook of patients at a time of increasing incidence.

Current state and future directions of pleural mesothelioma imaging

The diagnosis, staging, and response assessment of mesothelioma pose unique challenges to radiologic imaging. No single, conventional imaging approach captures the information necessary to direct all aspects of patient management. Instead, the complexities of this unique disease demand the integration of elements cleverly adapted from different modalities. Imaging-based studies presented at the 8th International Conference of the International Mesothelioma Interest Group (IMIG) in October 2006 sought to further define the current practice and future potential of radiology for the mesothelioma patient. The imaging studies selected through a peer-review process for presentation at the 2006 IMIG Conference were intended to frame this research in the context of the unique imaging challenges presented by mesothelioma while stimulating dialogue on the future resolution of these challenges. This communication conveys the pitfalls and potential of pleural mesothelioma imaging based on work presented at the Conference. From diagnosis to response, PET/CT to molecular bioprobes, volumetric analysis to computerized tumor assessment, imaging promises to provide valuable insight for patients with mesothelioma and the physicians who treat them.

Phase II Study of Vinflunine in Malignant Pleural Mesothelioma

Purpose

Malignant pleural mesothelioma (MPM) is a disease of increasing incidence for which treatment options are limited. This study reports the clinical efficacy data for vinflunine, a novel microtubule inhibitor, in MPM.

Patients and Methods

Patients with a histologically confirmed diagnosis of MPM were eligible for enrollment onto this multicenter phase II trial if they had not received prior chemotherapy or radiotherapy and had measurable lesions by Response Evaluation Criteria in Solid Tumors (RECIST) criteria. Vinflunine 320 mg/m2 by 10-minute intravenous infusion was administered on day 1 of 21-day cycles. Modifications of dose and schedule were made according to National Cancer Institute Common Toxicity Criteria version 2.0. Efficacy was assessed by an external, independent radiologist. The one-sample multiple testing procedure of Fleming was applied at the predetermined recruitment stages of 20 and 40 assessable patients.

Results

Sixty-seven patients were enrolled. Five patients were not assessable for tumor response. The response rate was 13.8% (95% CI, 6.5% to 24.7%). The median survival was 10.8 months (95% CI, 7.8 to 12.0 months). The most common adverse events were anemia, neutropenia, fatigue, constipation, and nausea. Of grade 3 and 4 toxicities, neutropenia and constipation were the most common (45% and 9% of patients, respectively).

Conclusion

Vinflunine can be delivered with high-dose intensity in patients with MPM. The response rate and median survival are encouraging for a single agent. These data suggest that vinflunine should be further evaluated in the management of MPM.

Assessment of tumor response in malignant pleural mesothelioma

Most patients with malignant pleural mesothelioma (MPM) are candidates for chemotherapy during the course of their disease. Assessment of the response with conventional criteria based on computed tomography (CT) measurements is challenging, due to the circumferential and axial pattern of growth of MPM. Such difficulties hinder an accurate evaluation of clinical study results and make the clinical management of patients critical. Several radiological response systems have been proposed, but neither WHO criteria nor the more recent RECIST unidimensional criteria nor hybrid uni- and bidimensional criteria seem to apply to tumor measurement in this disease. Recently, modified RECIST criteria for MPM have been published. Although they are already being used in current clinical trials, they have been criticized based on the high grade of inter-observer variability and on theoretical studies of mesothelioma growth according to non-spherical models. Computer-assisted techniques for CT measurement are being developed. The use of FDG-PET for prediction of response and, more importantly, of survival outcomes of MPM patients is promising and warrants validation in large prospective series. New serum markers such as osteopontin and mesothelin-related proteins are under evaluation and in the future might play a role in assessing the response of MPM to treatment.

Imaging response assessment in oncology

The role of imaging in the clinical setting as well as in the drug development process is expanding rapidly. Imaging technology now exists that is capable of detecting tumor response within hours. In parallel with this advance, a new array of more targeted and specific therapies are being developed. This paradigm shift in turn demands a more sophisticated way of quantifying response. There is a need to update and modify the current response evaluation criteria in solid tumors (RECIST), which rely solely on anatomic size measurement of tumors. In addition, response assessment guidelines will need to be increasingly disease-specific. Response assessment by imaging is now intimately involved with all stages of the drug development process, from exploratory drug discovery through clinical trials, as well as in clinical use. Imaging biomarkers and surrogate endpoints have the potential to speed drug approval significantly. The major funding institutions and the pharmaceutical industry are working more and more with researchers to help maintain progress in this multidisciplinary area involving oncologists, radiologists, molecular imaging specialists, medical physicists, and computer scientists.