Interferon (IFN)-alpha and IFN-gamma in combination with methotrexate: in vitro sensitivity studies in four human mesothelioma cell lines

Antitumor activity from the combined application of poly(I:C) and chemotherapeutics in human metastatic pharyngeal cell lines

BACKGROUND

Toll-like receptor 3 (TLR3) activation in tumor cells induces apoptosis. We investigated the effect of TLR3 ligand (poly(I:C)) in combination with chemotherapeutics applied to human pharyngeal carcinoma cells as a possible antitumor therapy.

METHODS

Human pharyngeal cancer cell lines were studied (FaDu and Detroit 562). Cytotoxicity assays and apoptosis assays (annexin V staining and caspase 3/7 activity measurements) were used to investigate the cytotoxic effects. By using TLR3 siRNA we confirmed that the observed effect is TLR3-dependent.

RESULTS

We found that the combined application of poly(I:C) and chemotherapeutics (cisPt, HU, 5-FU and MTX) has a stronger inhibitory effect on cell growth in tumor cells expressing functional TLR3 as compared with a single treatment. This is a result of TLR3-dependent apoptosis.

CONCLUSION

Our study showed that a combined application of the two agents already being used in tumor therapy could lower the necessary dosage of chemotherapeutics, leading to fewer side effects.

Gene expression profiles in human mesothelioma cell lines in response to interferon-γ treatment

Interferon-gamma (IFN-gamma) has been found to be antiproliferative and antitumoral in malignant mesothelioma (MM), but the MM cell response to IFN-gamma has not been fully characterized so far. We investigated gene expression profiles in human MM cell lines (HMCLs) exposed to IFN-gamma. Four HMCLs showing different sensitivities to the antiproliferative effect of IFN-gamma, two of them presenting a defect in the JAK/STAT signaling pathway, were treated with 500 IU/mL of IFN-gamma. Gene expression patterns were studied at 6 and 72 hours after exposure to the IFN-gamma, using a cDNA array technique. Six genes were studied with real-time reverse transcription-polymerase chain reaction. The gene expression profiles in response to IFN-gamma were shown to differ in different HMCLs. Numerous genes involved in cell proliferation and cell adhesion were regulated by IFN-gamma in JAK/STAT-deficient HMCLs. Genes possibly involved in regulation of cell proliferation included CDC2, PLK1, and IGFBP4, as well as several genes involved in cell-cell interactions and cell adhesion. The cDNA array technique revealed differences in expression pathways, especially those involved in cell growth, cell adhesion, and cell proliferation, between IFN-gamma-resistant and -sensitive MM cell lines. We found that the changes in gene expression profiles of HMCLs exposed to IFN-gamma were also related to features other than the antiproliferative response.

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.

Intrapleural infusion of activated macrophages and gamma-interferon in malignant pleural mesothelioma: a phase II study

STUDY OBJECTIVES

Intrapleural immunotherapy has shown some activity in patients with malignant mesothelioma. We conducted a multicentric pilot phase II study to evaluate the tolerance and the activity of intrapleurally infused autologous human activated macrophages (AM Phi) in patients with stage IA, IB, and IIA malignant pleural mesothelioma (MPM).

DESIGN

AM Phi derived from in vitro monocyte culture were infused into the pleura of patients every week for 8 consecutive weeks. Each infusion was followed 3 days later by an intrapleural injection of 9 millions units of gamma-interferon (gamma-IFN) in an attempt to prolong the in vivo activation of infused AM Phi. Response was assessed by CT scan and thoracoscopy when possible. If the patient's disease progressed after AM Phi treatment, an additional treatment was left to the choice of the investigator.

PATIENTS

Nineteen patients with histologically proven stage IA, IB, or IIA MPM were enrolled. Two patients were excluded before any AM Phi infusion because of complications impeding infusion. Seventeen patients were actually treated. After completion of the AM Phi cellular therapy, 10 patients were treated with chemotherapy as their diseases progressed.

RESULTS

The overall response rate of patients actually treated was 14%. When including the two patients enrolled but not treated, the overall response "in intention to treat" was 11%; two patients had a partial response, with a duration of response of 30 months and 3 months, respectively. One patient, who could not be evaluated by thoracoscopy because of pleural symphysis, is still alive without any clinical or radiologic sign of disease 69 months after treatment. No major adverse effects were observed during the infusion of either AM Phi or gamma-IFN, and there was no interruption of treatment because of toxicity. However, symphysis was observed in 7 of 14 patients who received the complete treatment. The median survival of patients actually treated, including those who received chemotherapy after AM Phi, was 29.2 months.

CONCLUSION

Combined infusion of AM Phi and gamma-IFN was well tolerated in patients with MPM; however, it had limited antitumor activity.

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.

Inhibition of mesothelioma cell growth in vitro by doxycycline

Malignant mesothelioma causes profound morbidity and nearly universal mortality that is often refractory to conventional treatment modalities of aggressive surgery, radiotherapy, or chemotherapy. Doxycycline, a commonly used antibiotic, has anti-tumor activity against several malignancies, but its anti-tumor effects on malignant mesothelioma have not been evaluated. We report here that concentrations of doxycycline achievable in serum with typical oral doses had cytostatic effects to varying extent on all eight of the mesothelioma cell lines studied but did not affect normal lung fibroblasts. Doxycycline inhibited the production of mitochondrial cytochrome c oxidase, especially in mesothelioma cells more sensitive to its cytostatic effects, and directly inhibited gelatinase A activity; both of these activities are putative mechanisms for the cytostatic activity of doxycycline in other tumor cells. Thus doxycycline may have a role as adjuvant therapy for malignant mesothelioma.

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.

Docetaxel and irinotecan (CPT-11) in the treatment of malignant pleural mesothelioma--a feasibility study

We chose to treat malignant pleural mesothelioma with a combination of docetaxel and irinotecan (CPT-11), because there have been preliminary reports that CPT-11 is active against mesothelioma, and docetaxel and CPT-11 were the most active agents in our in vitro experiments in human mesothelioma cell lines. Fifteen previously untreated patients with pleural mesothelioma (IMIG Stage III-IV) were given docetaxel 60 mg/m2 followed by CPT-11 190 mg/m2 on day 1, repeated every 3 weeks. All the patients were evaluable for toxicity and 13 patients were evaluated for response. No objective responses (complete or partial) were achieved, but there were two minor responses (overall response rate 15%) each of a duration of 4 months. Three patients had stable disease (23%); median time to progression was 7 months. Median survival in all the patients was 8.5 months from the first chemotherapy cycle and 11 months from diagnosis. Toxicity was severe with seven of 15 patients suffering neutropenic fever and six of 15 patients grade 3-4 diarrhea. The trial was discontinued because of toxicity and lack of activity. We do not recommend the combination of docetaxel and CPT-11 using the schedule presented here for further investigation in malignant mesothelioma. However, CPT-11 and docetaxel, individually, still warrant further study in this disease, especially in combination with cisplatin.

In vitro sensitivity of normal human mesothelial and malignant mesothelioma cell lines to four new chemotherapeutic agents

In this study, we used four human mesothelioma cell lines (M14K, M24K, M25K and M38K), one transformed human mesothelial cell line (MeT-5A) and one primary mesothelial culture (UPL) to test for in vitro sensitivity to docetaxel, paclitaxel, SN-38 [an active metabolite of irinotecan (CPT-11)] and gemcitabine, as single agents. Subconfluent cell cultures were treated with 2x10(-9), 5x10(-9), 10(-8), 2x10(-8) and 5x10(-8) M concentrations of each drug for 48 h. The sensitivity was measured in terms of cell viability using the Trypan blue exclusion method. All four drugs were potent inhibitors of mesothelioma cell growth, but cell lines from different patients diverged in their sensitivity to the individual agents. In most cases docetaxel, paclitaxel and SN-38 were more potent killers of mesothelioma cells than gemcitabine. The induction of DNA damage was investigated using the Comet assay; cells from two cell lines (M14K and M25K) were treated with subtoxic 10(-8) M concentrations of each drug for 4, 24 and 48 h. Each of the agents caused a slight increase in DNA single-strand breaks at a concentration of 10(-8) M.

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.

Long-term third chronic phase of chronic myelogenous leukemia maintained by interferon-alpha and methotrexate

The prognosis of blast crisis (BC) of chronic myelogenous leukemia (CML) is extremely poor despite many efforts to induce remission with chemotherapy. We have recently treated a long-surviving CML patient who developed three separate episodes of BC. The administration of interferon-alpha (IFN-alpha) alone as maintenance therapy was incapable of preventing BC, which occurred twice in the first 2 years after the diagnosis of CML. Intensive chemotherapy using enocitabine, mitoxantrone, and etoposide was effective to induce hematological remission. Thereafter once per week oral administration of methotrexate (10-15 mg/week) was combined with IFN-alpha after the second BC. This treatment succeeded in obtaining a major cytogenetic response and keeping him in third chronic phase for 5 years until the last most recent third BC. We present here the rare clinical course of the patient, review the past literature, and discuss the efficacy of the combination of IFN-alpha and methotrexate in this disease.

Interferon-gamma (IFN-gamma) as a potential radio- and chemo-protectant

Interferons (IFN) have had increasing clinical usage in the treatment of a variety of disorders, at times being used in combination with chemo- or radiotherapy. However, interferons may have inhibitory effects on hematopoietic stem cell proliferation and the effects of this cytokine's use on long-term hematologic function have not been studied. We performed the competitive repopulation assay in the murine system, using cells exposed to irradiation or single-dose chemotherapy with or without concomitant IFN-gamma use. IFN-gamma alone had no deleterious effects on hematopoietic stem cell productivity. We measured the repopulating ability of exhaustible multilineage precursors that were present at early stages of marrow repopulation after competitive repopulation (30 days). These progenitors were minimally impacted by cyclophosphamide (CTX) with or without IFN-gamma. Irradiation (XRT) and CTX alone produced significant repopulating defects in the most primitive hematopoietic stem cell, PHSC. Addition of IFN to either treatment regimen resulted in protection of PHSC, with improved repopulating ability, although the levels of donor marrow reached control levels only when CTX and IFN were used together. The results of multiple use of IFN with chemotherapy must be studied further, but IFN may offer hematologic radio- and chemoprotection, in addition to its antitumor properties in clinical protocols for treatment of cancers.

Lovastatin induces apoptosis in malignant mesothelioma cells

Malignant mesothelioma causes profound morbidity and nearly universal mortality that is refractory to conventional treatment with aggressive surgery, radiotherapy, or chemotherapy. We report that pharmacologic concentrations of lovastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitor, induced apoptosis in human malignant mesothelioma cell lines. Mesothelioma cell viability was decreased in a dose-dependent manner by lovastatin (5 to 30 microM). These effects were not reversed by exogenous growth factors or cholesterol, but were reversed by addition of 100 microM mevalonate, confirming that lovastatin affected mesothelioma viability by inhibiting mevalonate synthesis. Lovastatin appeared to decrease mesothelioma viability by inducing apoptosis, as indicated by morphologic changes, histologic evidence of nuclear condensation and degeneration, and flow-cytometric analysis of DNA content. Lovastatin's effects on cell viability were partially reversed in the presence of farnesol, and treatment of mesothelioma cells with a specific farnesyl-protein transferase (FTP) inhibitor decreased cell viability and induced morphologic changes indistinguishable from those caused by lovastatin. In addition, lovastatin-treated cells showed translocation of ras guanosine triphosphate (GTP)-binding proteins from membrane to cytosolic fractions on Western blots, suggesting that lovastatin's effects on mesothelioma were mediated in part by disrupting acylation of GTP-binding proteins. Thus, lovastatin is a commercially available and clinically well-tolerated agent that reduces viability and induces apoptosis of mesothelioma cells, and may provide the basis for adjunctive treatments of patients with mesothelioma.