Spotlight on bevacizumab and its potential in the treatment of malignant pleural mesothelioma: the evidence to date

Malignant Pleural Mesothelioma: A Comprehensive Review

Mesotheliomas are hyperplastic tumors that envelop the serosal membranes that safeguard the body's external surfaces. Although certain instances may exhibit indolent characteristics, a significant number of tumors demonstrate rapid progression and a poor prognosis. Mesotheliomas are typically categorized as benign or malignant, with malignant mesothelioma being more frequently linked to asbestos exposure. Malignant pleural mesothelioma (MPM) predominantly impacts males and often emerges in the late 50 s or beyond, characterized by a median age of early 70 s among patients exposed to asbestos lasting from 2 to 4 decades. Respiratory exposure to asbestos particles leads to the development of malignant mesothelioma, characterized by recurrent inflammation, disruption of cell division, activation of proto-oncogenes, and generation of free radicals. In pleural mesothelioma, BAP1, CDKN2A, and NF are the most often mutated genes. Accurate diagnosis and assessment usually require the use of chest computed tomography (CT) scans, magnetic resonance imaging (MRI), and positron emission tomography (PET). Radiation therapy, immunotherapy, chemotherapy, and surgery are some of the treatment options that are currently available. This systematic review provides a comprehensive analysis of the latest research, biomarkers, evaluation, and management strategies for malignant pleural mesothelioma.

Case report: complete response and long-term survival on third-line immunotherapy in patient with pleural mesothelioma

Introduction

Pleural mesothelioma (PM) is a rare neoplasm with median survival time range from 8 to 14 months from diagnosis, and the 5-year survival rate less than 10%, indicating a poor prognosis. The standard treatment for unresectable PM for a long time has been polychemotherapy with pemetrexed and cisplatin for fit patients. Currently, the combination of the anti PD-1 inhibitor nivolumab and the anti-CTLA4 inhibitor ipilimumab has been recognized as the best possible frontline therapy (especially in the sarcomatoid or biphasic type) due to improved outcomes compared to the standard chemotherapy combination. There are still no established predictive biomarkers for any type of systemic therapy in this disease.

Case presentation

Patient who presented with cough and dyspnea has been diagnosed with advanced epithelioid type PM in May 2016. He was treated with three lines of therapy, including an antiangiogenic agent and immunotherapy with pembrolizumab in the third line. Immunotherapy with the PD-1 inhibitor pembrolizumab achieved a complete and prolonged response that transferred to long- term survival. Seven years from diagnosis, the patient is still alive. Histological findings showed an unusually immune-inflamed tumor microenvironment possibly leading to excellent response on immunotherapy.

Conclusions

The course of the disease in our patient points out that we need better predictive biomarkers to direct the treatment algorithm, as some of the patients, although chemorefractory to the best chemotherapy option, can sustain great benefit of second-line chemotherapy in combination with antiangiogenic agent, and especially immunotherapy, even in late lines of therapy.

Biological basis for novel mesothelioma therapies

Mesothelioma is an aggressive cancer that is associated with exposure to asbestos. Although asbestos is banned in several countries, including the UK, an epidemic of mesothelioma is predicted to affect middle-income countries during this century owing to their heavy consumption of asbestos. The prognosis for patients with mesothelioma is poor, reflecting a failure of conventional chemotherapy that has ultimately resulted from an inadequate understanding of its biology. However, recent work has revolutionised the study of mesothelioma, identifying genetic and pathophysiological vulnerabilities, including the loss of tumour suppressors, epigenetic dysregulation and susceptibility to nutrient stress. We discuss how this knowledge, combined with advances in immunotherapy, is enabling the development of novel targeted therapies.

Advances in Immunotherapy of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) represents the uncommon cancer originating from pleural mesothelial cells, which is associated with dismal prognostic outcome. According to CheckMate-743 results, nivolumab plus ipilimumab has been approved to treat the unresectable MPM in treatment-naive patients as a first-line therapy by the FDA in October 2020. Immunotherapy is expected to be the best choice for MPM treatment. In the following article, the past treatment plan and the progress of immunotherapy for MPM will be reviewed.

Malignant pleural mesothelioma: recent developments

PURPOSE OF REVIEW

Malignant pleural mesothelioma (MPM) is a rare, but aggressive tumor with still poor prognosis. In this article, we focus on recent developments in the management of MPM including diagnosis, staging, biomarkers, and treatment strategies.

RECENT FINDINGS

Molecular markers such as programmed death-ligand 1 (PDL-1), Breast Cancer gene 1-associated protein gene, and cyclin-dependent kinase inhibitor 2A (CDKN2A) have prognostic impact and should be considered for assessment in patient samples. In addition to histological subtype and tumor pattern, tumor volumetry plays an increasing important role in staging, assessment of treatment response, and prediction of survival. Several new blood-based biomarkers have been recently reported including peripheral blood DNA methylation, microRNAs, fibulin, and high-mobility group box 1, but have not been established in clinical routine use yet. Regarding treatment, targeted therapies, immunotherapy, and vaccination are considered as new promising strategies. Moreover, extended pleurectomy/decortication is favored over extrapleural pneumonectomy (EPP) and intensity-modulated radiotherapy represents a possible approach in combination with EPP and pleurectomy/decortication. Intracavitary treatment options are promising and deserve further investigations.

SUMMARY

Overall, there has not been a real breakthrough in the treatment of MPM. Further research and clinical trials are needed to evaluate outcome and to identify new potential treatment candidates.

The Impact on Outcome by Adding Bevacizumab to Standard Induction Chemotherapy Prior to Mesothelioma Surgery: A Retrospective Single Center Analysis

Objectives

Adding bevacizumab, an anti-Vascular Endothelial Growth Factor (VEGF), to platinum-based chemotherapy/pemetrexed in 1^st line treatment of advanced malignant pleural mesothelioma (MPM), significantly improved overall survival. However, increased high grade bleeding after operation was reported in patients with colorectal cancer who previously received bevacizumab. In the present analysis, we assessed for the first time the impact of adding bevacizumab to induction chemotherapy prior to surgery for mesothelioma patients.

Methods

Two hundred twenty-seven MPM patients, intended to be treated with induction chemotherapy followed by surgery at the University Hospital of Zurich between 2002 and December 2018, were included in the present analysis. After propensity score matching for gender, histology and age (1:3 ratio), data from 88 patients were analyzed. Sixty-six patients underwent induction chemotherapy (with cis-/carboplatin and pemetrexed: control group) alone and 22 patients underwent induction chemotherapy with the addition of bevacizumab (bevacizumab group) prior macroscopic complete resection (MCR). Perioperative and long-term outcome variables were analyzed.

Results

Patients undergoing combination treatment with bevacizumab had a significantly better response than with chemotherapy alone as assessed by modified RECIST (p=0.046). Intraoperative complications in the bevacizumab group (one patient), or in the control group (three patients) were not related to intraoperative bleeding. Postoperative transfusion of blood products occurred in a larger amount in the control group than in the bevacizumab group (p=0.047). Overall survival was not statistically different between both groups.

Conclusion

These initial data demonstrate that MCR can be performed safely after triple induction chemotherapy with bevacizumab without increased intra- and postoperative bleeding complications. Response rates were significantly improved by the addition of bevacizumab.

Clinical Implementation of a Free-Breathing, Motion-Robust Dynamic Contrast-Enhanced MRI Protocol to Evaluate Pleural Tumors

OBJECTIVE. The purpose of this study was to develop a motion insensitive clinical dynamic contrast-enhanced MRI (DCE-MRI) protocol to assess the response of pleural tumors in clinical trials. MATERIALS AND METHODS. Thirty-two patients with pleura-based lesions were administered contrast material and imaged with gradient-recalled echo DCE-MRI sequence variants: either a traditional cartesian k-space acquisition (FLASH), a time-resolved imaging with stochastic trajectories acquisition (TWIST), or a radial stack-of-stars acquisition (radial) sequence in addition to other standard-of-care imaging sequences. Each image acquisition's sensitivity to motion was evaluated by comparing the motion of the thoracic border in 3D throughout the acquisition. One-way ANOVA was used to compare the image quality between different acquisitions. The 95% CIs were calculated for mean thoracic border displacement. The effects of motion on kinetic parameter estimation were explored with simulations according to clinically acquired data. RESULTS. Radial was the most motion-robust sequence with subvoxel mean displacement in the superior-inferior direction (0.4 ± 1.2 [SD] mm). FLASH showed intermediate displacement (4.6 ± 2.0 mm), whereas TWIST was most sensitive to motion (6.4 ± 3.4 mm). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the images acquired with the radial sequence were on par or better than the FLASH and TWIST sequences when reconstructed with an improved density compensation algorithm. Simulations showed that motion on scans showing pleural-based lesions can lead to markedly inaccurate kinetic parameter estimation and inappropriate kinetic model convergence within a nested model analysis. CONCLUSION. A practical radial k-space trajectory sequence that provides motion-insensitive pharmacokinetic parameters was incorporated as part of the DCE-MRI protocol of pleural tumors. Validation and usefulness in clinical trials assessing response to therapy is needed.

Tumour Treating Fields in combination with pemetrexed and cisplatin or carboplatin as first-line treatment for unresectable malignant pleural mesothelioma (STELLAR): a multicentre, single-arm phase 2 trial

BACKGROUND

Tumour Treating Fields (TTFields) are a regional, antimitotic treatment for solid tumours, which is based on the delivery of low-intensity alternating electric fields. The aim of the STELLAR study was to test the activity of TTFields delivered to the thorax in combination with systemic chemotherapy for the front-line treatment of patients with unresectable malignant pleural mesothelioma.

METHODS

STELLAR was a prospective, single-arm, phase 2 trial done at 12 European academic and non-academic sites (five in Italy, three in Poland, one in France, one in Belgium, one in Spain, and one in the Netherlands) for treatment-naive patients with histologically confirmed unresectable malignant pleural mesothelioma. Patients were aged at least 18 years, had an Eastern Cooperative Oncology Group performance status of 0-1, and at least one measurable or evaluable lesion according to modified Response Evaluation Criteria in Solid Tumors for mesothelioma. Patients received continuous TTFields at a frequency of 150 kHz to the thorax and concomitant chemotherapy with intravenous pemetrexed (500 mg/m² on day 1) plus intravenous platinum (either cisplatin 75 mg/m² on day 1 or carboplatin area under the curve 5 on day 1) every 21 days for up to six cycles. Patients not progressing after completion of chemotherapy received TTFields as maintenance treatment until progression, patient or physician decision, or unacceptable toxic effects. The primary endpoint of the trial was overall survival. Survival analyses were done in the intention-to-treat population, and safety analyses were done in all patients who received at least 1 day of TTFields treatment. This trial is registered with ClinicalTrials.gov, NCT02397928.

FINDINGS

Between Feb 9, 2015 and March 21, 2017, 80 patients were enrolled in the study. Median follow-up was 12·5 months (IQR 7·4-16·6). Median overall survival was 18·2 months (95% CI 12·1-25·8). The most common grade 3 or worse adverse events were anaemia (nine [11%] patients), neutropenia (seven [9%]), and thrombocytopenia (four [5%]). Skin reaction was the only adverse event associated with TTFields and was reported as grade 1-2 in 53 (66%) patients, and as grade 3 in four (5%) patients. No treatment-related deaths were observed.

INTERPRETATION

The trial showed encouraging overall survival results, with no increase in systemic toxicity. TTFields (150 kHz) delivered to the thorax concomitant with pemetrexed and platinum was an active and safe combination for front-line treatment of unresectable malignant pleural mesothelioma. Further investigation in a randomised trial is warranted.

FUNDING

Novocure.

Approved and emerging treatments of malignant pleural mesothelioma in elderly patients

Introduction: Malignant pleural mesothelioma (MPM) is a rare neoplasm with asbestos exposure as the dominant etiologic agent. Owing to the long latent period following exposure, MPM is often diagnosed late in life. Despite this, elderly patients are under-represented in clinical trials. To date, data regarding the tolerability and efficacy of anticancer treatments for elderly patients affected by MPM are still lacking.Areas covered: The current state-of-the-art of approved treatments employed in the treatment of MPM elderly patients is reviewed and discussed, with a look to emerging therapies. A structured search of bibliographic databases for peer-reviewed research literature and of main meeting abstracts using a focused review question was undertaken.Expert opinion: Even though the median age of MPM patients enrolled in the most recent experimental trials is increasing, no specific analysis has been reported so far in the elderly. Moreover, no data are available for the 'oldest of the elderly' (>75 years). Treatment of elderly patients with MPM is one of the major challenges to the clinician. There is a clear need of large, well-conducted retrospective studies and above all of prospective investigations in this patient population, both in the first-and in the second-line setting.

Synergistic Enhancement of Cellular Uptake With CD44-Expressing Malignant Pleural Mesothelioma by Combining Cationic Liposome and Hyaluronic Acid-Lipid Conjugate

Malignant pleural mesothelioma (MPM) is a highly aggressive form of cancer, with a median survival of less than 1 year. It is well known that the hyaluronan (HA) receptor CD44 is highly expressed by MPM cells and is reported to be correlated with a poor prognosis. We herein report on the development of a new type if drug delivery system against CD44 that involves the use of lipid nanoparticles (LNPs) equipped with a new type of HA derivative. In this study, we evaluated HA-lipid conjugation (HAL) via the end of the HA molecule through reductive amination, a process that allowed the carboxylate group to remain intact. As a result, the HAL-modified LNP appears to be a potent nanoparticle for dealing with MPM. Surprisingly, the use of a combination of a cationic lipid and HAL had a synergistic effect on cellular uptake in MPM and consequently permitted an anti-cancer drug such as cis-diamminedichloro-platinum(II) (CDDP). Intrapleural injection of CDDP-loaded HAL-LNP (1.5 mg/kg as CDDP) per week significantly suppressed the progression of this type of cancer in an MPM orthotopic model. These results suggest that HAL-modified LNP represents a potent delivery system for MPM cells that express high levels of CD44.

Current chemotherapy strategies in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive malignancy with a 5-year survival rate of ~10%. Since most patients present with irresectable disease, the vast majority is treated with chemotherapy. The only registered therapy for MPM is platinum-pemetrexed doublet therapy, although only up to half of patients have clinical benefit from this palliative treatment. Of the anti-angiogenesis agents, only bevacizumab and nintedanib have shown activity with platinum-pemetrexed doublet therapy. Other anti-angiogenesis agents like thalidomide did not prolong (progression free) survival or response rate. Eventually, all patients will get a recurrence and no active second line therapy has been identified to date. The clinical benefit of (switch) maintenance therapy after first line treatment and combination strategies of different chemotherapies with angiogenesis inhibitors are currently under investigation. The major challenges are finding optimal treatment combinations and to select the adequate treatment for an individual patient. This review focusses on the current standard of chemotherapy and new systemic therapy strategies under investigation.

Heterogeneous Contributing Factors in MPM Disease Development and Progression: Biological Advances and Clinical Implications

Malignant pleural mesothelioma (MPM) tumors are remarkably aggressive and most patients only survive for 5–12 months; irrespective of stage; after primary symptoms appear. Compounding matters is that MPM remains unresponsive to conventional standards of care; including radiation and chemotherapy. Currently; instead of relying on molecular signatures and histological typing; MPM treatment options are guided by clinical stage and patient characteristics because the mechanism of carcinogenesis has not been fully elucidated; although about 80% of cases can be linked to asbestos exposure. Several molecular pathways have been implicated in the MPM tumor microenvironment; such as angiogenesis; apoptosis; cell-cycle regulation and several growth factor-related pathways predicted to be amenable to therapeutic intervention. Furthermore, the availability of genomic data has improved our understanding of the pathobiology of MPM. The MPM genomic landscape is dominated by inactivating mutations in several tumor suppressor genes; such as CDKN2A; BAP1 and NF2. Given the complex heterogeneity of the tumor microenvironment in MPM; a better understanding of the interplay between stromal; endothelial and immune cells at the molecular level is required; to chaperone the development of improved personalized therapeutics. Many recent advances at the molecular level have been reported and several exciting new treatment options are under investigation. Here; we review the challenges and the most up-to-date biological advances in MPM pertaining to the molecular pathways implicated; progress at the genomic level; immunological progression of this fatal disease; and its link with developmental cell pathways; with an emphasis on prognostic and therapeutic treatment strategies.

Sialic acid-binding lectin from bullfrog eggs inhibits human malignant mesothelioma cell growth in vitro and in vivo

Malignant mesothelioma is an aggressive cancer that results from exposure to asbestos. The therapeutic options for this type of cancer are limited; therefore, the development of novel therapeutic agents is urgently required. Sialic acid-binding lectin isolated from Rana catesbeiana oocytes (cSBL) is a novel therapeutic candidate for cancer, which exhibits antitumor activity mediated through RNA degradation. In the present study, we evaluated the effect of cSBL in vitro and in vivo. Xenograft-competent H2452 and MSTO human mesothelioma cell lines were treated with cSBL, and the pathway by which cSBL induces apoptosis was analyzed. In vivo studies were performed using nude mice inoculated with one of the two cell lines, and the effects of cSBL and pemetrexed were monitored simultaneously. Furthermore, the pharmacological interactions between the three agents (pemetrexed, cisplatin and cSBL) were statistically assessed. It was demonstrated that cSBL treatments caused morphological and biochemical apoptotic changes in both cell lines. Caspase cascade analysis revealed that an intrinsic pathway mediated cSBL-induced apoptosis. The administration of cSBL significantly inhibited tumor growth in two xenograft models, without any adverse effects. Furthermore, the combination index and dose reduction index values indicated that the cSBL + pemetrexed combination showed the highest synergism, and thus potential for reducing dosage of each drug, compared with the other combinations, including the existing pemetrexed + cisplatin regimen. cSBL exerted prominent antitumor effects on malignant mesothelioma cells in vitro and in vivo, and showed favorable effects when combined with pemetrexed. These results suggest that cSBL has potential as a novel drug for the treatment of malignant mesothelioma.

Role of bevacizumab in the management of the patient with malignant pleural effusion: more questions than answers

INTRODUCTION

Malignant pleural effusion (MPE) is a feature of metastatic cancer associated with significant morbidity and cost. The typical management of MPE is systemic chemotherapy and mechanical intervention. Vascular endothelial growth factor (VEGF), an inducer of vascular permeability, has been shown to mediate fluid formation. Therefore, bevacizumab, an inhibitor of VEGF, offers theoretical promise for abolishing fluid formation in MPE. Areas covered: This review begins with a summary of VEGF physiology and evidence of its role in MPE pathogenesis. This is followed by an overview of bevacizumab and major trials that put it on the map of non-small cell lung cancer (NSCLC). The majority of the article is devoted to a review of the current evidence base for the use of bevacizumab for MPE control in metastatic pleural malignancy. The review concludes with considerations of patient selection and toxicity. Expert commentary: Evidence in support of bevacizumab administration for MPE management remains flawed. Small studies suggest efficacy of both intravenous and intrapleural routes, but their design raises bias concerns. Bevacizumab appears to be safe in properly selected cases. The future of MPE management may de-emphasize VEGF inhibition in favor of precise molecular therapeutics that could address the root cause of tumorigenesis.

New Strategies Using Antibody Combinations to Increase Cancer Treatment Effectiveness

Antibodies have proven their high value in antitumor therapy over the last two decades. They are currently being used as the first-choice to treat some of the most frequent metastatic cancers, like HER2⁺ breast cancers or colorectal cancers, currently treated with trastuzumab (Herceptin) and bevacizumab (Avastin), respectively. The impressive therapeutic success of antibodies inhibiting immune checkpoints has extended the use of therapeutic antibodies to previously unanticipated tumor types. These anti-immune checkpoint antibodies allowed the cure of patients devoid of other therapeutic options, through the recovery of the patient’s own immune response against the tumor. In this review, we describe how the antibody-based therapies will evolve, including the use of antibodies in combinations, their main characteristics, advantages, and how they could contribute to significantly increase the chances of success in cancer therapy. Indeed, novel combinations will consist of mixtures of antibodies against either different epitopes of the same molecule or different targets on the same tumor cell; bispecific or multispecific antibodies able of simultaneously binding tumor cells, immune cells or extracellular molecules; immunomodulatory antibodies; antibody-based molecules, including fusion proteins between a ligand or a receptor domain and the IgG Fab or Fc fragments; autologous or heterologous cells; and different formats of vaccines. Through complementary mechanisms of action, these combinations could contribute to elude the current limitations of a single antibody which recognizes only one particular epitope. These combinations may allow the simultaneous attack of the cancer cells by using the help of the own immune cells and exerting wider therapeutic effects, based on a more specific, fast, and robust response, trying to mimic the action of the immune system.

Amatuximab and novel agents targeting mesothelin for solid tumors

Mesothelin (MSLN) is considered a promising target for cancer therapy. Originally extracted in 1992 after the immunization of mice with a human ovarian cancer (OC) cell line and cloned in 1996, MSLN seems to be involved in cell adhesion and metastasis. MSLN is prevalent in mesothelia tissues but is expressed in several human cancers, such as OC, pancreatic cancer, mesothelioma, and lung cancer. Amatuximab (MORAb-009) is a mouse-human chimeric monoclonal antibody with a selective affinity for MSLN. The principal mechanism of action comprises inhibition of binding of MSLN with the antigen CA125/MUC16. The highest phase of development is actually a Phase II trial (MORAb-009-201, Europe). In this review, we describe the mechanism of action of amatuximab and other MSLN-targeting novel drugs, along with a discussion about the expected efficacy, safety, and toxicity of this promising group of agents and implications for future research and clinical practice.