Effect of interferon-alpha 2a on malignant mesothelioma

Diffuse Pleural Mesothelioma: Advances in Molecular Pathogenesis, Diagnosis, and Treatment

Diffuse pleural mesothelioma (DPM) is a highly aggressive malignant neoplasm arising from the mesothelial cells lining the pleural surfaces. While DPM is a well-recognized disease linked to asbestos exposure, recent advances have expanded our understanding of molecular pathogenesis and transformed our clinical practice. This comprehensive review explores the current concepts and emerging trends in DPM, including risk factors, pathobiology, histologic subtyping, and therapeutic management, with an emphasis on a multidisciplinary approach to this complex disease.

How Our Continuing Studies of the Pre-clinical Inbred Mouse Models of Mesothelioma Have Influenced the Development of New Therapies

Asbestos-induced preclinical mouse models of mesothelioma produce tumors that are very similar to those that develop in humans and thus represent an ideal platform to study this rare, universally fatal tumor type. Our team and a number of other research groups have established such models as a stepping stone to new treatments, including chemotherapy, immunotherapy and other approaches that have been/are being translated into clinical trials. In some cases this work has led to changes in mesothelioma treatment practice and over the last 30 years these models and studies have led to trials which have improved the response rate in mesothelioma from less than 10% to over 50%. Mouse models have had a vital role in that improvement and will continue to play a key role in the future success of mesothelioma immunotherapy. In this review we focus only on these original inbred mouse models, the large number of preclinical studies conducted using them and their contribution to current and future clinical therapy for mesothelioma.

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.

Integrated genomics point to immune vulnerabilities in pleural mesothelioma

Pleural mesothelioma is an aggressive malignancy with limited effective therapies. In order to identify therapeutic targets, we integrated SNP genotyping, sequencing and transcriptomics from tumours and low-passage patient-derived cells. Previously unrecognised deletions of SUFU locus (10q24.32), observed in 21% of 118 tumours, resulted in disordered expression of transcripts from Hedgehog pathways and the T-cell synapse including VISTA. Co-deletion of Interferon Type I genes and CDKN2A was present in half of tumours and was a predictor of poor survival. We also found previously unrecognised deletions in RB1 in 26% of cases and show sub-micromolar responses to downstream PLK1, CHEK1 and Aurora Kinase inhibitors in primary mesothelioma cells. Defects in Hippo pathways that included RASSF7 amplification and NF2 or LATS1/2 mutations were present in 50% of tumours and were accompanied by micromolar responses to the YAP1 inhibitor Verteporfin. Our results suggest new therapeutic avenues in mesothelioma and indicate targets and biomarkers for immunotherapy.

Immunotherapy strategies for mesothelioma - the role of tumor specific neoantigens in a new era of precision medicine

INTRODUCTION

Immunotherapy has long been considered a potential therapy for malignant mesothelioma and is currently being pursued as such. Some of the early phase clinical trials involving immunomodulators have demonstrated encouraging results and numerous clinical trials are underway to further investigate this treatment approach in various treatment settings and larger patient cohorts. Areas covered: This review summarizes the current and emerging clinical evidence for checkpoint blockade and other immunotherapeutic strategies in mesothelioma. The mesothelioma tumor immune microenvironment and mutational landscape are also discussed, including their impact on treatment strategies. We also provide an evaluation of the current evidence for neoantigen targeted personalized immunotherapy. Expert opinion: Immune checkpoint inhibitors work by unleashing the host immune response against probable neoantigens. Despite impressive activity in a small subset of patients and the potential for prolonged responses, most patients experience treatment failure. Neoantigen vaccines provide a potential complementary therapeutic strategy by increasing the immunogenic antigen load, which can lead to an increased tumor specific immune response. Further research is needed explore this treatment option in mesothelioma and technological advances are required to translate this concept into clinical practice.

Oncolytic Viral Therapy for Mesothelioma

The limited effectiveness of conventional therapy for malignant pleural mesothelioma demands innovative approaches to this difficult disease. Even with aggressive multimodality treatment of surgery, radiation, and/or chemotherapy, the median survival is only 1–2 years depending on stage and histology. Oncolytic viral therapy has emerged in the last several decades as a rapidly advancing field of immunotherapy studied in a wide spectrum of malignancies. Mesothelioma makes an ideal candidate for studying oncolysis given the frequently localized pattern of growth and pleural location providing access to direct intratumoral injection of virus. Therefore, despite being a relatively uncommon disease, the multitude of viral studies for mesothelioma can provide insight for applying such therapy to other malignancies. This article will begin with a review of the general principles of oncolytic therapy focusing on antitumor efficacy, tumor selectivity, and immune system activation. The second half of this review will detail results of preclinical models and human studies for oncolytic virotherapy in mesothelioma.

New directions in mesothelioma treatment

For most patients with mesothelioma, symptom control and palliative chemotherapy are mainstays of care. First-line cisplatin/pemetrexed chemotherapy has demonstrated survival and quality-of-life benefits. A randomized controlled trial adding bevacizumab to cisplatin and pemetrexed recently reported improved survival and time to progression, and may constitute a new standard of care where economically viable. Immunotherapy is under active investigation and positive results have been reported from single-arm studies of the anti-CTLA4 antibody tremelimumab; the anti-PD-1 antibody pembrolizumab; and mesothelin-targeting strategies. Symptom control remains critical for patient well-being, and includes management of pleural effusion, analgesia, treatment of symptomatic masses and management of systemic symptoms. There is increasing evidence that tunneled pleural catheters are preferred over talc pleurodesis for recurrent pleural effusion.

Intracavitary therapeutics for pleural malignancies

Pleural malignancies are ideal for novel therapeutic approaches because they are invariably fatal. Intrapleural (IP) chemotherapy has only marginal benefit in pleural malignancies, but may prove efficacious with hyperthermic chemotherapy administered in combination with maximal tumor debulking. IP immunotherapies may be most effective in those patients with early-stage pleural malignancy, and may prove superior to standard pleurodesis methods in control of effusion and prolongation of survival. Immunogene therapy may be unable to successfully treat bulky tumors on its own, but success may be achieved with combination approaches that combine debulking surgery and chemotherapy with IP genetic immunotherapy.

Oncolytic measles viruses encoding interferon beta and the thyroidal sodium iodide symporter gene for mesothelioma virotherapy

Mesothelioma usually leads to death within 8–14 months of diagnosis. To increase the potency of oncolytic measles viruses (MVs) for mesothelioma therapy, we inserted the interferon β (IFNβ) gene alone or with the human thyroidal sodium iodide symporter (NIS) gene into attenuated MV of the Edmonston lineage. The corresponding mouse IFNβ (mIFNβ) viruses, MV-mIFNβ and MV-mIFNβ-NIS, successfully propagated in human mesothelioma cells, leading to intercellular fusion and cell death. High levels of mIFNβ were detected in the supernatants of the infected cells, and radioiodine uptake was substantial in the cells infected with MV-mIFNβ-NIS. MV with mIFNβ expression triggered CD68-positive immune cell infiltration 2–4 times higher than MV-GFP injected into the tumor site. The numbers of CD31-positive vascular endothelial cells within the tumor were decreased at day 7 after intratumoral injection of MV-mIFNβ or MV-mIFNβ-NIS, but not after MV-GFP and PBS administration. Immunohistochemical analysis showed that MV-mIFNβ changed the microenvironment of the mesothelioma by increasing innate immune cell infiltration and inhibiting tumor angiogenesis. Oncolytic MVs coding for IFNβ effectively retarded growth of human mesotheliomas and prolonged survival time in several mesothelioma tumor models. The results suggest that oncolytic MVs that code for IFNβ and NIS will be potent and versatile agents for the treatment of human mesothelioma.

What's the place of immunotherapy in malignant mesothelioma treatments?

Malignant pleural mesothelioma (MPM) is a rare malignancy of the pleura with a very poor prognosis. Treatments evaluated for malignant mesothelioma, including chemotherapy, radiotherapy and surgery are of limited efficacy. However, the fact that the tumors of some patients with MPM regress spontaneously or respond to immunotherapy suggests that the immune system may respond to MPM under some circumstances. In this respect, animal studies have demonstrated immunoreactivity of MPM to different immunotherapies. In the case of MPM, several clinical studies have demonstrated a correlation between the presence of a lymphocyte infiltrate and a better prognosis and humoral response directed against specific antigens related to tumor. Thus, MPM immunotherapy is undoubtedly a highly promising but also very challenging approach to the treatment of this disease that has slipped through the defense lines of the immune system. This article reviews past and recent developments of the clinical strategies that concern immunotherapy of mesothelioma.

Targeting the effector site with IFN-alphabeta-inducing TLR ligands reactivates tumor-resident CD8 T cell responses to eradicate established solid tumors

Effective antitumor CD8 T cell responses may be activated by directly targeting the innate immune system within tumors. We investigated this response by injecting a range of TLR agonists into established tumors using a mouse model of malignant mesothelioma stably transduced with the hemagglutinin (HA) gene as a marker Ag (AB1-HA). Persistent delivery of the dsRNA mimetic poly(I:C) into established AB1-HA tumors resulted in complete tumor resolution in 40% of mice, with the remaining mice also showing a significant delay in tumor progression. Experiments in athymic nude mice along with CD8 depletion and IFN-alphabeta blocking studies revealed that tumor resolution required both CD8 T cells and type I IFN induction, and was associated with local changes in MHC class I expression. Surprisingly, however, tumor resolution was not associated with systemic dissemination or tumor infiltration of effector CD8 T cells. Instead, the antitumor response was critically dependent on the reactivation of tumor-resident CD8 T cell responses. These studies suggest that, once reactivated, pre-existing local CD8 T cell responses are sufficient to resolve established tumors and that in situ type I IFN is a determining factor.

A phase I clinical trial of single-dose intrapleural IFN-beta gene transfer for malignant pleural mesothelioma and metastatic pleural effusions: high rate of antitumor immune responses

PURPOSE

This phase 1 dose escalation study evaluated the safety and feasibility of single-dose intrapleural IFN-beta gene transfer using an adenoviral vector (Ad.IFN-beta) in patients with malignant pleural mesothelioma (MPM) and metastatic pleural effusions (MPE).

EXPERIMENTAL DESIGN

Ad.IFN-beta was administered through an indwelling pleural catheter in doses ranging from 9 x 10(11) to 3 x 10(12) viral particles (vp) in two cohorts of patients with MPM (7 patients) and MPE (3 patients). Subjects were evaluated for (a) toxicity, (b) gene transfer, (c) humoral, cellular, and cytokine-mediated immune responses, and (d) tumor responses via 18-fluorodeoxyglucose-positron emission tomography scans and chest computed tomography scans.

RESULTS

Intrapleural Ad.IFN-beta was generally well tolerated with transient lymphopenia as the most common side effect. The maximally tolerated dose achieved was 9 x 10(11) vp secondary to idiosyncratic dose-limiting toxicities (hypoxia and liver function abnormalities) in two patients treated at 3 x 10(12) vp. The presence of the vector did not elicit a marked cellular infiltrate in the pleural space. Intrapleural levels of cytokines were highly variable at baseline and after response to gene transfer. Gene transfer was documented in 7 of the 10 patients by demonstration of IFN-beta message or protein. Antitumor immune responses were elicited in 7 of the 10 patients and included the detection of cytotoxic T cells (1 patient), activation of circulating natural killer cells (2 patients), and humoral responses to known (Simian virus 40 large T antigen and mesothelin) and unknown tumor antigens (7 patients). Four of 10 patients showed meaningful clinical responses defined as disease stability and/or regression on 18-fluorodeoxyglucose-positron emission tomography and computed tomography scans at day 60 after vector infusion.

CONCLUSIONS

Intrapleural instillation of Ad.IFN-beta is a potentially useful approach for the generation of antitumor immune responses in MPM and MPE patients and should be investigated further for overall clinical efficacy.

Gene Therapy for Malignant Pleural Mesothelioma

Gene therapy for mesothelioma is currently in its adolescence. The expansion of knowledge regarding molecular aspects of mesothelioma carcinogenesis has facilitated the development of promising gene therapy modalities that target specific oncoproteins and mutant tumor suppressor genes. Although implementation of any of these gene therapy approaches as part of standard medical care for patients who have mesothelioma remains years in the future, the field is finally progressing toward more definitive phase II/III efficacy studies. Unfortunately, the marginal benefits garnered from standard anticancer treatments in mesothelioma argue strongly for continued participation in clinical studies of various experimental approaches, particularly gene therapy. These trials serve multiple purposes: to establish safety, determine proper dosing, evaluate for efficacy, and, in an iterative fashion, guide future avenues of laboratory investigation.

Ifosfamide, mesna, and interferon-alpha2A combination chemoimmunotherapy in malignant mesothelioma: results of a single center in central anatolia

Our aim was to determine the efficacy of ifosfamide, mesna, and interferon alpha combination therapy in malignant mesothelioma (MM) patients. Fourty-two patients (39 evaluable) with histologically proven MM were enrolled into this study from January 1999 to October 2002. The drug schedule consisted of a combination of ifosfamide, 3000 mg/m2 1-3 d intravenous infusion (iv), the uroprotective agent mesna, 3000 mg/m2 1-3 d iv every 3 wk, and interferon alpha2a, 4.5 MU subcutaneously (sc) 3 d/wk for 6 mo as first-line chemotherapy. Overall, 140 cycles were administered to the 39 patients (median, 3.5 cycles; range, 1 to 6 cycles). Among the 39 patients, 8 partial remissions (PR) (21%) were observed. Thirteen patients (33%) had stable disease for at least 8 wk and 18 (46%) had progressive disease. Overall survival (OAS) and progression free survival (PFS) for all patients were 10.0 +/- 2.9 mo (95%CI 4.3-15.7) and 5.0 +/- 1.9 mo (95%CI 1.38-8.62), respectively. One and two year survival rates were calculated as 39% and 5%, respectively. All of the PR patients had the epithelial type of MM. Their survival time was 21.0 +/- 5.7 mo (95% CI 9.9-32.1) and significantly longer than that of nonresponders (p=0.0061). The toxicity of the drug combination was mild and well tolerated. There were no treatment-related deaths. Grade 3-4 neutropenia and febrile neutropenia were seen in 10 patients (26%) and 3 patients (8%), respectively. Chemotherapy was stopped in three patients because of renal function deficiency. One of these patients who had peritoneal MM required hemodialysis. In conclusion, this combination therapy showed encouraging antitumor activity with modest toxicity.

Soluble type II transforming growth factor-beta receptor inhibits established murine malignant mesothelioma tumor growth by augmenting host antitumor immunity

PURPOSE

Transforming growth factor (TGF)-beta blockade has been proposed as an anticancer therapy; however, understanding which tumor patients might benefit most from such therapy is crucial. An ideal target of such inhibitory therapy might be malignant mesothelioma (MM), a highly lethal, treatment-resistant malignancy of mesothelial cells of the pleura and peritoneum that produces large amounts of TGF-beta. The purpose of this study was to explore the possible therapeutic utility of TGF-beta blockade on MM.

EXPERIMENTAL DESIGN

To evaluate this hypothesis, we tested the effects of a soluble TGF-beta type II receptor (sTGF-beta R) that specifically inhibits TGF-beta1 and TGF-beta 3 in three different murine MM tumor models, AB12 and AC29 (which produce large amounts of TGF-beta) and AB1 (which does not produce TGF-beta).

RESULTS

Tumor growth of both established AB12 and AC29 tumors was inhibited by sTGF-beta R. In contrast, AB1 tumors showed little response to sTGF-beta R. The mechanism of these antitumor effects was evaluated and determined to be primarily dependent on immune-mediated responses because (a) the antitumor effects were markedly diminished in severe combined immunodeficient mice or mice depleted of CD8(+) T cells and (b) CD8(+) T cells isolated from spleens of mice treated with sTGF-beta R showed strong antitumor cytolytic effects, whereas CD8(+) T cells isolated from spleens of tumor-bearing mice treated with of control IgG2a showed no antitumor cytolytic effects.

CONCLUSIONS

Our data suggest that TGF-beta blockade of established TGF-beta-secreting MM should be explored as a promising strategy to treat patients with MM and other tumors that produce TGF-beta.

Chemotherapy for malignant pleural mesothelioma: past results and recent developments

This review summarises results of previously conducted clinical trials and subsequently presents data arising from all phase II-III studies on chemotherapy for malignant pleural mesothelioma (MPM) published since the last relevant overview. While response rates exceeding 30% have barely been achieved with established cytotoxic drugs in MPM therapy, novel chemotherapeutic agents and their combinations appear somewhat more promising. This applies especially to the antimetabolites, and in particular to pemetrexed which produced response rates of up to 45% in combination with platinum compounds. Raltitrexed combined with oxaliplatin has also been shown to be effective, and gemcitabine--applied as a single agent or in combination with cisplatin--as well as vinorelbine appear to improve quality of life in patients presenting with MPM. Data can now be more precisely analysed by increasingly implemented randomised studies, applying a standardised staging system, and distinguishing prognostic groups. While chemotherapy for MPM remains a challenging task, important steps have clearly been made in the past years to combat this aggressive disease. Publication of results from a phase III trial of pemetrexed with cisplatin in a peer reviewed journal may soon establish a standard of care.

Integration of Multimodality Approaches in the Management of Malignant Pleural Mesothelioma

More than half a century after the first descriptions of mesothelioma as a pathologic entity, satisfactory treatment is still elusive. Although relatively uncommon, the incidence of mesothelioma will most likely increase over the next 10-20 years. Advances have been made in understanding the pathogenesis, diagnosis, and staging, but they have not translated into markedly improved survival. Some use palliative treatment as the primary means of therapy even now. On the other hand, a cadre of individuals have studied how surgery, chemotherapy, and radiation therapy affect the disease. Although each individual modality has had limited success by itself, a multimodality approach has been documented to improve survival and quality of life. In addition, intriguing discoveries in immunology and gene profiling and therapy promise hope for further improvement. In this article, we will illustrate the current views on integrating these different approaches and delineate areas of active research.

Potential of interferon-alpha in solid tumours: part 2

The second part of this review examines the use of recombinant interferon-alpha (rIFNalpha) in the following solid tumours: superficial bladder cancer, Kaposi's sarcoma, head and neck cancer, gastrointestinal cancers, lung cancer, mesothelioma and ovarian, breast and cervical malignancies. In superficial bladder cancer, intravesical rIFNalpha has a promising role as second-line therapy in patients resistant or intolerant to intravesical bacille Calmette-Guérin (BCG). In HIV-associated Kaposi's sarcoma, rIFNalpha is active as monotherapy and in combination with antiretroviral agents, especially in patients with CD4 counts >200/mm(3), no prior opportunistic infections and nonvisceral disease. rIFNalpha has shown encouraging results when used in combination with retinoids in the chemoprevention of head and neck squamous cell cancers. It is effective in the chemoprevention of hepatocellular cancer in hepatitis C-seropositive patients. In neuroendocrine tumours, including carcinoid tumour, low-dosage (</=3 MU) or intermediate-dosage (5 to 10 MU) rIFNalpha is indicated as second-line treatment, either with octreotide or alone in patients resistant to somatostatin analogues. Intracavitary IFNalpha may be useful in malignant pleural effusions from mesothelioma. Similarly, intraperitoneal IFNalpha may have a role in the treatment of minimal residual disease in ovarian cancer. In breast cancer, the only possible role for IFNalpha appears to be intralesional administration for resistant disease. IFNalpha may have a role as a radiosensitising agent for the treatment of cervical cancer; however, this requires confirmation in randomised trials. On the basis of current evidence, the routine use of rIFNalpha is not recommended in the therapy of head and neck squamous cell cancers, upper gastrointestinal tract, colorectal and lung cancers, or mesothelioma. Pegylated IFNalpha (peginterferon-alpha) is an exciting development that offers theoretical advantages of increased efficacy, reduced toxicity and improved compliance. Further data from randomised studies in solid tumours are needed where rIFNalpha has activity, such as neuroendocrine tumours, minimal residual disease in ovarian cancer, and cervical cancer. A better understanding of the biological mechanisms that determine response to rIFNalpha is needed. Studies of IFNalpha-stimulated gene expression, which are now feasible, should help to identify molecular predictors of response and allow us to target therapy more selectively to patients with solid tumours responsive to IFNalpha.

Chemotherapy for malignant pleural mesothelioma

This paper covers the outcome of previously conducted clinical trials on chemotherapy for malignant pleural mesothelioma and presents data from recent phase II and phase III trials. In contrast to conventional cytotoxic drugs, which have barely produced response rates exceeding 30%, recently introduced chemotherapeutic agents and their combinations promise to be more effective. Especially pemetrexed has yielded response rates of up to 45% in combination with platinum compounds. Furthermore, raltitrexed-oxaliplatin has shown promising activity and gemcitabine was found to improve quality of life in patients with malignant pleural mesothelioma when applied as a single agent or in combination with cisplatin. Based on robust phase III study results, pemetrexed-cisplatin may soon be considered with chemotherapy for this aggressive disease.

Activity of chemotherapy and immunotherapy on malignant mesothelioma: a systematic review of the literature with meta-analysis

The role of chemotherapy for unresectable malignant mesothelioma is unclear. The aims of the present study were to evaluate the methodological quality of published papers relative to chemotherapy or immunotherapy in malignant mesothelioma and to aggregate, for trials having a similar methodology, the response rates in order to identify the most active chemotherapeutic drugs and regimens. The literature relative to this topic, published between 1965 and June 2001 was reviewed. A methodological qualitative evaluation was performed according to the European Lung Cancer Working Party scale, specifically designed for phase II trials. A study was considered as potentially positive if the upper limit of the 95% confidence interval (CI) of the response rate was greater than 20% and positive if the lower limit of the 95% CI was > 20%. Eighty-three studies (88 treatment arms) were eligible for the systematic review. Fifty-three arms were considered as positive or potentially positive. No statistically significant difference in the methodological quality was observed between negative and positive studies. Studies were aggregated in four groups according to the presence of cisplatin and/or doxorubicin in the treatment regimen. The combination of cisplatin and doxorubicin had the highest response rate (28.5%; P < 0.001). Cisplatin was the most active single-agent regimen. Our systematic qualitative and quantitative overview of the literature suggests that the most active chemotherapeutic regimen, in term of objective response rate, is the combination of cisplatin and doxorubicin and the best single-agent is cisplatin. The combination of these two drugs can be recommended as control arm for future randomised phase III trials.

Phosphatase and tensin analog gene overexpression engenders cellular death in human malignant mesothelioma cells via inhibition of AKT phosphorylation

BACKGROUND

Abnormal phosphatase and tensin analog (PTEN) gene expression has been noted in neoplasms. The PTEN protein cleaves phosphate groups from cellular growth kinases, inhibiting tumor propagation. A downstream target of PTEN is AKT, a serine-threonine kinase that when activated inhibits apoptosis. We sought to determine whether PTEN overexpression in mesothelioma cells would engender hypophosphorylation of AKT and apoptosis.

METHODS

Human malignant mesothelioma cell lines REN and I-45 were transfected with adenoviral vectors AdPTEN and AdBgal (marker gene) at various multiplicities of infection (MOI). Cell viability was measured using a colorimetric assay, and apoptosis was assessed by morphology and subG1 fluorescence-activated cell sorter (FACS) analysis. PTEN protein and AKT phophorylation were evaluated by Western blot, and AKT kinase activity was evaluated by functional assay.

RESULTS

Increased cellular killing was noted with AdPTEN gene transfer. The ratio of cell killing with AdPTEN to AdBgal widened with increasing MOI and was statistically significant at all MOI. Cells demonstrated apoptosis by morphologic and subG1 FACS analyses. Cells overexpressing PTEN demonstrated decreased phosphorylated (active) AKT and AKT kinase activity compared with controls.

CONCLUSIONS

Overexpression of PTEN engenders apoptosis in mesothelioma by AKT hypophosphorylation. The forced overexpression of PTEN may prove useful clinically in this treatment-resistant neoplasm.

New approaches for mesothelioma: biologics, vaccines, gene therapy, and other novel agents

Although malignant mesothelioma is not a classically immunogenic cancer, there is abundant evidence for immune recognition. The relative ease of obtaining tumor tissue makes mesothelioma ideal for studying surrogate biomarkers such as lymphocytic infiltration or expression of transduced genes. There is evidence that malignant mesothelioma patients as well as asbestos-exposed persons without mesothelioma have impaired immune responsiveness. Substantial progress has been made in animal models using several biological and immunological techniques, but clinical application has been problematic. Systems studied have included lysis by interleukin-2 (IL-2)-activated lymphokine-activated killer (LAK) cells, tumor necrosis factor-alpha (TNF-alpha), a p16-expressing adenovirus vector, suicide gene therapy using the herpes simplex virus-tyrosine kinase (HSV-tk) followed by ganciclovir, and immunomodulatory gene therapy with IL-2, IL-4, interferon-gamma (IFN-gamma), IFN-alpha, TNF-alpha, granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-6, and IL-1beta transfected into tumors. Vaccinia virus has been studied as a vector for cytokine gene transfer. Suicide gene therapy has been combined with a tumor vaccine. The University of Western Australia is initiating a pilot study of autologous vaccination in malignant mesothelioma. Novel agents under study include the angiogenesis inhibitors SU5416, bevacizumab, and thalidomide. ZD1839, an orally administered, highly selective inhibitor of the epidermal growth factor receptor (EGFR) tyrosine kinase, is being tested in a phase II trial. Since platelet-derived growth factor (PDGF) is thought to be an autocrine growth factor for mesothelioma STI-571 (Gleevec; Novartis, Basel, Switzerland), a highly selective inhibitor of the PDGF receptor tyrosine kinase, is being tested in a phase II trial. The development of more active cytotoxic combinations in this disease should facilitate further studies of chemoimmunotherapy. It seems likely that no single treatment modality will be effective by itself.

Prognostic factors in diffuse malignant pleural mesothelioma: effects of pretreatment clinical and laboratory characteristics

The aim of this study was to investigate the effects of various pretreatment clinical and laboratory characteristics on the survival of patients with diffuse malignant pleural mesothelioma (DMPM). One hundred histopathologically confirmed DMPM patients were evaluated. Fifty-nine were treated with chemoimmunotherapy while 41 who had refused chemoimmunotherapy received supportive therapy alone. The following pretreatment characteristics were evaluated in both univariate and multivariate Cox regression analyses: age, gender, Karnofsky performance score (KPS), histology asbestos exposure, presence of chest pain, dyspnoea, weight loss, symptom duration, smoking history, disease location, platelet count, haemoglobin, white blood cell (WBC) count, serum lactate dehydrogenase (LDH) and extent of disease (stage). Univariate analysis showed that patients with age > or = 75 years, male gender, smoking history advanced stages above stage I disease, KPS < 70, WBC count > or = 8450 and LDH level > or = 500 IU l(-1) have a worse prognosis. With multivariate Cox regression analyses, age > or = 75 years, advanced stages above stage I disease, KPS < 70 and LDH level > or = 500 IU l(-1) were found to be indicators of a poorer prognosis. In conclusion, in our study each of low performance status, older age, advanced stage disease, high LDH level and prognosis were found to be related.

Combined regimen of cisplatin, doxorubicin, and alpha-2b interferon in the treatment of advanced malignant pleural mesothelioma: a Phase II multicenter trial of the Italian Group on Rare Tumors (GITR) and the Italian Lung Cancer Task Force (FONICAP)

BACKGROUND

The cisplatin-doxorubicin combination has shown moderate activity in malignant pleural mesothelioma (MPM; objective response, 25%), and preclinical studies suggest that interferons (IFNs) may have an antiproliferative effect on mesothelioma cell lines with a marked increase in cisplatin cytotoxicity. Therefore, the combined chemoimmunotherapy regimen is an worthwhile approach to evaluate in a Phase II trial.

METHODS

From December 1995 to June 1999, 37 previously untreated patients with MPM were treated with cisplatin 60 mg/m(2) intravenously on Day 1 plus doxorubicin 60 mg/m(2), recycled every 3-4 weeks and IFN-alpha-2b, 3 x 10((6)) international units subcutaneously 3 times a week for a total of 6 courses or until progression. Inclusion criteria were histologic diagnosis of MPM and measurable disease defined by computed tomography scan or magnetic resonance imaging.

RESULTS

Thirty-four patients were assessable for toxicity and 35 for efficacy according to World Health Organization criteria. One hundred thirty-five courses were administered with a median of 4 cycles per patients. Seventy-six percent of patient presented at least 1 episode of severe myelosuppression (Grade 3 and 4). Severe anemia and thrombocytopenia occurred in 30% and 24% of patients, respectively. Sixty percent of patients presented constitutional symptoms. In the 35 patients assessable for response, the overall response rate was 29% (95% confidence interval, 15-47%). The median duration of response was 8.4 months. With a median follow-up of 19.6 months, the median survival was 9.3 months. One- and 2-year survival was 45% and 34%, respectively.

CONCLUSIONS

This combined regimen has definite activity in MPM. However, toxicity, particularly myelosuppression and fatigue, is not negligible and may limit its application.

The immune anti-tumor effects of GM-CSF and B7-1 gene transfection are enhanced by surgical debulking of tumor

Malignant mesothelioma (MM) is a solid tumor largely unresponsive to conventional therapies. Immunological gene therapy shows promise in murine models and human clinical trials; however, the role of surgery in combination with gene therapy has not been widely studied. The aim of this study was to determine if debulking surgery improved the effectiveness of gene therapy in a murine MM model. Mice were subcutaneously inoculated with the MM cell line, AC29, at two different sites, 4 days apart, to allow a surgical and distal site tumor to develop. Once tumors were established, the surgical site tumor was debulked and vaccination of syngeneic tumor transfectants encoding genes for IL-4, IL-2, GM-CSF, B7-1 or allogeneic MHC molecules commenced at a site away from both tumors, and tumor growth was measured. Neither debulking surgery nor gene therapy alone delayed tumor growth. However, there was a clear delay of tumor growth when debulking surgery was combined with vaccination of tumor transfectants expressing B7-1 or high levels of GM-CSF. Combinations of these two transfectants did not lead to a synergistic effect. This study demonstrates that debulking surgery can augment the immunostimulatory effects of immunological gene therapy and can delay tumor growth. This has implications for the future design of human gene therapy trials for solid tumors such as MM.

Malignant pleural mesothelioma

Malignant pleural mesothelioma remains a difficult tumor to treat, much less cure. Currently, the best chance for long-term survival lies with early diagnosis and aggressive surgical extirpation, but given the typically long delay between the onset of symptoms and diagnosis, this is only possible with a high index of suspicion and an aggressive diagnosis workup. Early referral to a tertiary center experienced in the treatment of MPM may be important for several reasons: (1) decreased risk of tumor spread along multiple thoracenesis/biopsy tracts, (2) the availability of specialized pathologic assays for definitive diagnosis, (3) the availability of critical staging modalities (aggressive mediastinoscopy +/- thoracoscopy, MRI scans performed according to specific mesothelioma protocols, and perhaps PET scans), (4) surgical experience with pleurectomy/decortication and/or extrapleural pneumonectomy, that may decrease morbidity and mortality, and (5) the availability of novel adjuvant protocols. Single-modality therapy is unlikely to result in long-term survival. Aggressive surgery is required for optimal debulking, and extrapleural pneumonectomy may offer better local control compared with pleurectomy/ecortication. Delivery of optimal radiation schedules, which may involve large fractions as well as large total doses, is limited by the presence of nearby dose-limiting structures. Current chemotherapy is severely lacking in producing objective responses and improved survival although gemcitabine and IL-2 may be active agents to be combined with radiation and/or other agents. Hyperthermia, photodynamic therapy, intracavitary therapy, and gene therapy are all relatively new techniques under active investigation that should be supported by enrollment in on-going protocols. Predictably, many of these techniques provide greater benefit when used in the setting of adjuvant protocols or minimal residual disease, emphasizing the importance of multimodality therapy.

Localised spontaneous regression in mesothelioma -- possible immunological mechanism

Malignant mesothelioma (MM) is an aggressive tumor usually associated with asbestos exposure. Although it can remain stable for prolonged periods, it has not been described to spontaneously regress. MM tumors are thought to be immunogenic based both on animal studies and on the good responses in some humans treated with immunotherapy. Here we present a case of pleural MM in which a transient spontaneous regression was associated with tumor tissue infiltration with mononuclear cells and serological evidence of anti-MM reactivity. The patient's tumor eventually progressed and with this progression there was evidence of loss of serological reactivity to some, but not all, of her MM antigens. The patient survived for 20 months and, in contrast to her initial biopsy, no significant lymphoid infiltrate was detected in her MM tissue at post mortem examination.

Control of cell cycle progression in human mesothelioma cells treated with gamma interferon

Recombinant human interferon gamma (r-hu-IFNgamma) exerts both antitumoral activity in the early stages of human malignant mesothelioma and a cytostatic effect in human mesothelioma (HM) cell lines in vitro. The antiproliferative effect of interferons (IFNs) reported in a variety of cells has been attributed to several mechanisms. In order to progress in the understanding of HM cell growth modulation by r-hu-IFNgamma, modifications of cell cycle progression and expression of key cell cycle regulator proteins in response to r-hu-IFNgamma were examined. Nine HM cell lines were studied, including one resistant to the antiproliferative effect of r-hu-IFNgamma. Except in the resistant cell line r-hu-IFNgamma produced an arrest in the G1 and G2-M phases of the cell cycle, associated with a reduction in both cyclin A and cyclin dependent kinase inhibitors (CDKIs) expression. Moreover cyclin B1/cdc2 activity was decreased. The present study provides the first evidence of a G2-arrest in r-hu-IFNgamma-treated HM cell lines and indicates that HM cell lines, despite their tumorigenic origin still support cell cycle control. The cell cycle arrest induced by r-hu-IFNgamma seems to depend on cyclin regulation through p21(WAF1/CIP1)- and p27(Kip1)-independent mechanisms and is not directly related to the induced DNA damage.

Combination raltitrexed (Tomudex(R))-oxaliplatin: a step forward in the struggle against mesothelioma? The Institut Gustave Roussy experience with chemotherapy and chemo-immunotherapy in mesothelioma

The aim of this study was to review the experience of the Institut Gustave Roussy in 163 patients with malignant mesothelioma over a 9-year period. Data from seven consecutive prospective trials, four of chemo-immunotherapy and three of chemotherapy were reviewed. The rationale, methods and results of these trials are summarised and discussed. 98 patients were included in four phase II trials of chemo-immunotherapy whose common denominator was a combination of cisplatin and alpha-interferon. The response rate ranged from 15% to 40%. High-dose weekly cisplatin combined with alpha-interferon yielded the highest response rate but the toxicity of this regimen was considered unacceptable. Neither higher doses of alpha-interferon or the addition of mitomycin C or interleukin-2 to the regimen were able to enhance the activity of this combination. 18 patients were included in a paclitaxel-cisplatin phase II trial. The response rate was only 6% (95% confidence interval (CI): 0-24) and toxicity was also significant. This regimen was, therefore, considered ineffective. Of 17 patients with mesothelioma included in a phase I trial that combined raltitrexed and oxaliplatin, 6 (35%) obtained a partial response. Responses were seen even in cisplatin-refractory mesothelioma. Preliminary results of a subsequent ongoing phase II trial using raltitrexed (3 mg/m(2)) and oxaliplatin (130 mg/m(2)) have confirmed this promising activity with a 30% (9/30) response rate (95% CI: 15-49). The tolerance of this outpatient regimen is acceptable (no significant haematological toxicity and no alopecia) and compares favourably with that of our previous regimens. The final results concerning response and survival are required to confirm the efficacy of this combination. The preliminary results of two studies suggest promising activity with the combination of raltitrexed-oxaliplatin in malignant mesothelioma. The efficacy/toxicity ratio of this combination compares favourably with that of our previous chemotherapy and chemo-immunotherapy regimens.

Serologic responses in patients with malignant mesothelioma: evidence for both public and private specificities

Malignant mesothelioma (MM) is a pulmonary malignancy that appears to be immunogenic based on a large number of studies in both animals and humans. This notion is supported by our recent demonstration using Western blot analysis of immunoglobulin G antibodies reactive with a variety of autoantigens in many patients with MM. In view of the enormous potential of such antigens in early diagnosis, immunotherapy, and vaccination of at-risk individuals, it was essential to identify these antigens. We therefore applied the SEREX technique (serologic identification by recombinant expression cloning), using a serum pool from six patients as the probe against an expressed complementary DNA library derived from a cloned MM cell line. We screened over one million recombinants and obtained sequence information on eight antigens that had provoked immunoglobulin heavy chain class switching, presumably as a consequence of T-cell recognition. Six of these antigens were identifiable (U2AF[65], Siah binding protein, topoisomerase IIbeta, ZFM1, mIre1, and pendulin), and of the others, one was found as a single EST from a myotube library (Jemm-1); the other (Jemm-2) was not represented in any EST database even as a weak homolog. Consistent with our previous findings, each of the characterizable antigens would be expected to be associated with the cell nucleus. Each of the autoantibody specificities was uniquely associated with a single patient with the exception of antibodies to TOPIIbeta and U2AF(65). We found 13 of 14 (93%) patients with MM had antibodies to TOPIIbeta and two of 14 (14%) patients had antibodies to U2AF(65). The number of serum reactivities, taken as a measure of the complexity of the immune response, correlates with patient survival and with an index of systemic inflammation. These data suggest that a broader range of serologic reactivities reflects a more active host response to the presence of tumor.

Cytokine gene therapy of mesothelioma. Immune and antitumor effects of transfected interleukin-12

Malignant mesothelioma (MM) is a solid tumor of the mesothelium for which there is no curative treatment. MM appears to be sensitive to immunotherapeutic approaches, and one of the most powerful immunomodulatory cytokines with antitumor effects is interleukin (IL)-12. We have previously shown in a murine model of MM that systemic administration of recombinant IL-12 induces a potent anti-MM immune response. The nature and accessibility of MM tumors means that they are suitable candidates for direct cytokine and gene-transfer therapeutic approaches. Therefore, we undertook a study to assess the antitumor effects induced by the local production of IL-12 within MM tumors by transfecting a murine MM line with the genes for IL-12. The IL-12 transfectant (AB1-IL-12) did not produce tumors in normal mice, but did so in athymic nude mice, implicating T cells in the prevention of MM tumor growth. In mixing experiments, paracrine IL-12 production inhibited growth of untransfected MM cells provided that cells producing IL-12 represented more than 50-80% of the inoculum. Furthermore, BALB/c mice previously challenged with AB1-IL-12 were protected against rechallenge with parental AB1 tumor, indicating that the transfectant induced long-term immunity. AB1-IL-12 induced systemic immunity that was effective at reducing the incidence of parental AB1 tumor at a distal site, but its effects were dose-dependent. Though both CD4(+) and CD8(+) cells infiltrated the rejecting tumor, CD8(+) effector cells were essential for protection against development of parental AB1 tumor. This study shows that paracrine secretion of IL-12, generated by gene transfer, can induce immunity against MM that can act locally and also at a distant site. In addition, there was no evidence of toxicity, which has been associated with the systemic administration of IL-12, indicating that this cytokine is a good candidate for experimental gene therapy in MM.

Advances in the treatment of malignant pleural mesothelioma

Malignant pleural mesothelioma is a neoplasm that is commonly fatal and for which there are no widely accepted curative approaches. Mesothelioma is unresponsive to most chemotherapy and radiotherapy regimens, and it typically recurs even after the most aggressive attempts at surgical resection. Multimodality approaches have been of some benefit in prolonging survival of very highly selected subgroups of patients, but they have had a relatively small impact on the majority of the patients diagnosed with this disease. As the incidence of pleural mesothelioma peaks in the United States and Europe over the next 10 to 20 years, new therapeutic measures will be necessary. This review will discuss the roles of chemotherapy, radiotherapy, surgery, and combined modality approaches in the treatment of pleural mesothelioma, as well as scientific advances made in the past decade that have led to the development of experimental techniques, such as photodynamic therapy, immunotherapy, and gene therapy, that are currently undergoing human clinical trials. These promising new avenues may modify the therapeutic nihilism that is rampant among clinicians dealing with mesothelioma.

High-dose methotrexate in combination with interferons in the treatment of malignant pleural mesothelioma

Twenty six patients with pleural mesothelioma of UICC stage I-IV excluding M1 disease (46% of whom had stage I disease and 38% stage III disease) were treated intravenously with high dose MTX (3 g) and calcium folinate rescue three times at intervals of 2 weeks and three times at intervals of 3 weeks. Natural interferon (IFN)-alpha (3 MIU days 2-10) and recombinant IFN-gamma1b (50 microg m(-2) on days 2, 6 and 10) were injected subcutaneously after each MTX dose. At the end of MTX treatment the IFNs were continued as maintenance therapy until disease progression. Seven partial responses were observed among 24 patients evaluable for response (response rate 29%, 95% confidence interval 13-51%). Median duration of response was 10 months (range 3-24 months). Median survival was 17 months and 1-year and 2-year survival rates 62% and 31% respectively. The toxicity of the chemo-immunotherapy was acceptable. Treatment was stopped in one patient who developed grade IV neurological toxicity. MTX dose reductions were rare (two patients with grade 1-2 renal toxicity). The combination of high dose MTX and IFN-alpha and IFN-gamma is active against malignant pleural mesothelioma and well-tolerated. The survival rates are encouraging.

Cisplatin, mitomycin, and interferon-alpha2a combination chemoimmunotherapy in the treatment of diffuse malignant pleural mesothelioma

STUDY OBJECTIVE

To investigate the therapeutic activity and toxicity of combination chemoimmunotherapy with cisplatin, mitomycin, and interferon (IFN)-alpha2a, by comparing the responses in a group of patients with diffuse malignant pleural mesothelioma (DMPM) to the responses in a control group of DMPM patients given supportive care alone.

DESIGN

Patients with histopathologically confirmed DMPM were evaluated for treatment with chemoimmunotherapy.

SETTING

After the initial evaluation, all patients received either chemoimmunotherapy or supportive care from the Osmangazi University Medical Faculty, Department of Chest Diseases.

PATIENTS

Forty-three patients with DMPM received chemoimmunotherapy until the end of the survey; 19 patients were given supportive therapy alone after refusing chemoimmunotherapy.

INTERVENTIONS

Drugs were administered according to the following schedule: IV cisplatin, 30 mg/m2 qd on days 1 and 2; IV mitomycin, 8 mg/m2 on day 1; and subcutaneous IFN-alpha2a, 4.5 million IU twice weekly. The courses were repeated every 4 weeks.

RESULTS

Overall, 232 chemoimmunotherapy cycles were administered. A total of 10 objective responses (ORs) in 43 patients (23%) were assessed, including 2 complete responses (5%), 4 partial responses, and 4 regressions. Seventeen patients had stable disease, and 16 patients had progression. The median survival time was 11.5 months for the 43 patients who received chemoimmunotherapy and 7.0 months for the 19 patients who received supportive therapy alone. The difference in survival times between the chemoimmunotherapy and supportive therapy groups was not significant. However, the median survival time for the patients who had OR was 21.3 months, which is significantly longer than that of the patients who received supportive care alone and that of patients with progressive disease (6 months). The toxicities associated with the treatment schedule of this study were, for the most part, tolerable.

CONCLUSIONS

The drug combination used in this study is moderately effective and well tolerated in patients with DMPM, especially in those who responded to the treatment.

Weekly systemic combination of cisplatin and interferon alpha 2a in diffuse malignant pleural mesothelioma

The treatment of diffuse malignant pleural mesothelioma (DMPM) remains grim. Neither surgery, radiotherapy nor chemotherapy can be considered as a standard therapy. Immunotherapy with interferon (IFN) in combination with chemotherapy may be an interesting new approach. In 13 consecutive patients with DMPM, we used a weekly combination of cisplatin (CDDP) (60 mg/m2; day 2) and IFN alpha 2a (6 MU/day; days 1-4) in a protocol of two cycles of 4 weeks on/4 weeks off followed by 3 weeks on/3 weeks off. Total treatment duration was thus 25 weeks. In responders, IFN as maintenance monotherapy was continued for a further 6 months. There were nine males and four females with an average age of 65.3 years (range 51-72 years). Eleven had epithelial, one had mixed and one had a sarcomatoid form of DMPM. Five patients were classified as stage II, six as stage III and two as stage IV, as per the International Mesothelioma Interest Group. Thirty-five cycles were administered with a median of three cycles/patient (range 0.75-4). The median total cumulative dose of CDDP was 596 mg/m2 (range 114-861) and that of IFN alpha 2a was 264 MU (range 72-336). Four patients received IFN maintenance therapy, one for 3 months and three for 6 months. One patient had a complete response, four had a partial response, six had a stable disease and the disease progressed in one. One patient was non evaluable for response. All patients were assessable for toxicity. Hematological toxicity was the most frequently observed but was manageable (grade 3 anemia in five patients, grade 3 thrombocytopenia in three patients, grade 3 neutropenia in five patients). Grade 1 renal toxicity was observed in six patients, grade 2-3 asthenia in six patients and an average 5-kg weight loss was noted in nine patients. In conclusion, systemic combination of CDDP and IFN alpha 2a in large doses is effective at the expense of non-negligible toxicity.

Interleukin-12 induces an effective antitumor response in malignant mesothelioma

Malignant mesothelioma (MM) is a fatal solid tumor of the mesothelium for which there is currently no ameliorating treatment. Using our murine model of this malignancy, which closely resembles the human disease, we have shown that immunotherapy may be of value in the treatment of MM. Because recombinant interleukin-12 (rIL-12) has strong immunomodulatory effects in vivo, we studied the effects of rIL-12 on murine antitumor immune responses, using a nonimmunogenic murine MM tumor cell line (AB1) in vivo. Systemic administration of rIL-12 at the time of tumor inoculation prevented AB1 tumor growth in up to 70% of treated mice, 50% of which were still resistant to AB1 upon rechallenge, indicating that long-term immunologic antitumor effects had been established. This rIL-12-induced effect was dependent on the involvement of both CD4(+) and CD8(+) but not natural killer (NK) cells. Importantly, treatment of established tumors with intralesional injections of rIL-12 resulted in temporary tumor regression or growth inhibition. This effect was dependent on the continuous presence of rIL-12 and correlated with increased numbers of CD4(+) and CD8(+) cells infiltrating the remaining tumor mass. Effective inhibition of tumor growth also occurred when IL-12 was released within MM tumors by coadministration of MM cells that had been stably transfected with the gene for IL-12. These data indicate that IL-12 has potential in the immunotherapy of MM, through gene transfer or local cytokine administration, provided that significant intratumor levels of IL-12 can be achieved for prolonged periods.

Gene therapy for malignant pleural mesothelioma

Malignant mesothelioma (MM) is a fatal malignancy refractory to all forms of standard anticancer therapy. This article reports the results of a phase I clinical trial assessing the safety of intrapleural delivery and efficacy of intratumoral gene transfer of recombinant adenovirus (rAd) containing herpes simplex virus thymidine kinase (HSVtk) gene into the pleural space of patients with MM, followed by systematic treatment with the antiviral drug ganciclovir (GCV) for 14 days. AD.RSVtk/GCV gene therapy proved to be well tolerated, with evidence of significant gene transfer particularly at high vector doses and with elimination of preliminary biopsy. Ongoing gene therapy trials for mesothelioma at two other centers, focusing on immunostimulation and using suicide gene therapy as a tumor vaccine, are also reviewed in this article.

A review of chemotherapy trials for malignant mesothelioma

Treatment of malignant pleural mesothelioma continues to be frustrating regardless of the modality employed. Numerous trials of chemotherapeutic agents have been performed, but until recently, these studies were small and subject to inaccuracies of disease measurement. To our knowledge, no chemotherapeutic regimen has emerged as a standard of care. A review of the literature reveals that small activity against this disease has been shown by the anthracyclines, platinum compounds, and alkylating agents, whereas higher activity has been reported with the antimetabolites. The plant alkaloids have not demonstrated any activity against mesothelioma. Dose-escalated chemotherapeutic regimens may offer an advantage, whereas combination chemotherapy has not shown any benefit over single-agent therapy. Favorable responses have been reported with the administration of intrapleural biological response modifiers. Further trials and the investigation of new agents in the treatment of this disease are necessary.

Current approach to malignant mesothelioma of the pleura

Malignant mesothelioma of the pleura occurs primarily in individuals who were exposed to asbestos either in the workplace or home. The incidence of malignant mesothelioma is rising and, reflective of the malignancy's long latency period, is expected to continue to increase into the next century. Current treatment measures, including surgery, radiation therapy, chemotherapy, intrapleural therapy, and combined-modality therapies, have had varying impacts on survival. This paper explores current trends in the treatment of malignant pleural mesothelioma.

Patho- and immunobiology of malignant mesothelioma: characterisation of tumour infiltrating leucocytes and cytokine production in a murine model

Malignant mesothelioma (MM) is an aggressive, uniformly fatal serosal tumour, usually associated with asbestos exposure, for which there currently is no effective treatment. In order to gain insight into the mechanism(s) whereby MM might escape immune surveillance, a murine model for MM was used (a) to characterise the tumour-infiltrating lymphocytes (TIL) and macrophages (TIM) phenotypically, (b) to examine systemic immune recognition of MM, and (c) to examine the possible influence of tumour-derived cytokines on systemic and local pathobiological manifestations of MM. A profound down-regulation of lymphocyte surface markers, known to be involved in T cell activation, was found in TIL. Likewise, although TIM were present in large numbers, their expression of MHC class II antigen and integrins was weak or absent, suggestive of altered functional activity. Significant amounts of cytokines, in particular transforming growth factor beta, interleukin-6 (IL-6), IL-1 and tumour necrosis factor were produced during the course of MM tumour development-directly by the MM cells and/or indirectly in response to tumour growth. These factors may contribute both to derangement of antitumour effector mechanisms and to the clinical and pathological manifestations of the disease.

Interferon alpha and doxorubicin in malignant mesothelioma: a phase II study

BACKGROUND

Malignant mesothelioma is a tumour which is generally resistant to chemotherapy. While the addition of interferon to chemotherapy improves response rates in some other malignancies, such a combination has not been evaluated in the treatment of mesothelioma.

AIMS

To assess the anti-tumour effects and toxicity of interferon-alpha combined with doxorubicin in the treatment of pleural mesothelioma.

METHODS

Twenty five patients (mean age 54 +/- 11 years) were enrolled in a phase II study. All patients had a confirmed histological diagnosis, measurable tumour, a life expectancy of at least three months, and no prior chemotherapy or interferon. Interferon alpha-2a, 9 x 10(6) U sc daily, was administered together with doxorubicin 25 mg per m2 i.v. weekly, for 12 weeks. Response status was assessed by tumour measurements on clinical examination and thoracic CT scans before and after treatment.

RESULTS

A partial response was observed in four patients (16%; 90% CI, 8-30%), 11 remained stable, while six had progressive disease. Four patients withdrew within the first month because of toxicity. The median survival of all patients was 11 months (95% CI, 3-19). Dose modification as a result of toxicity was required in all patients. Lethargy, weight loss, leukopenia and vomiting were the most common side effects.

CONCLUSIONS

The combination of interferon-alpha and doxorubicin showed only modest activity and was associated with significant toxicity. It cannot be recommended in the treatment of malignant pleural mesothelioma.