The effect of systemic human interferon-alpha administration to patients with glioblastoma multiforme

Interferon-β inhibits glioma angiogenesis through downregulation of vascular endothelial growth factor and upregulation of interferon inducible protein 10

Interferon-β (IFN-β) has been used clinically for malignant glioma growth inhibition. Recently IFN-β is re-evaluated for its sensitization mechanism to the chemotherapeutic agent temozolomide, because angiogenesis is essential for malignant glioma growth. In this study, we investigated new mechanisms of inhibition of glioma angiogenesis by IFN-β. Three malignant glioma cell lines, U87, TK2 and Becker, were used for in vitro study. The effect of IFN-β for these cell lines were evaluated by means of proliferation (MTT assay), conditioned medium induced HUVEC migration, VEGF and interferon inducible protein 10 (IP10, angiogenesis inhibitor) expression by RT-PCR and western blot analysis. SCID mouse U87 subcutaneous model and U87 implant cranial window model were used for in vivo study. The effect of IFN-β with the models was evaluated by means of tumor growth, tumor tissue expression for VEGF and IP10, tumor tissue CD31 positive vessel densities, apoptosis and tumor microcirculation (blood velocity, interaction between leukocytes and endothelial cells). In vitro, IFN-β upregulated IP10 expression and downregulated VEGF expression time- (4–48 h) and dose- (10–5,000 U/ml) dependently. At the same dose, glioma cell-induced HUVEC migration was inhibited, but cell proliferation was not affected. IFN-β local and systemic injection at 10⁵ U and at 5×10⁵ U/day, for 15 days inhibited U87 subcutaneous growth significantly. In the tumor tissues, VEGF expression and vessel densities were downregulated, but IP10 expression and apoptosis index upregulated. In addition, IFN-β local injection increased collagen fiber deposition in the tumor tissues. IFN-β 5×10⁵ U/day, s.c. injection for 7 days reversed the decreased leukocyte adhesion to endothelial cells, but did not affect blood velocity and vessel images. One of the important roles of IFN-β for malignant glioma growth inhibition was anti-angiogenesis by directly inhibiting angiogenesis through downregulation of VEGF and upregulation of IP-10 and indirectly changing the tumor microcirculation and regulating the interstitial pressure.

Dendritic cell therapy of high-grade gliomas

The prognosis of patients with malignant glioma is poor in spite of multimodal treatment approaches consisting of neurosurgery, radiochemotherapy and maintenance chemotherapy. Among innovative treatment strategies like targeted therapy, antiangiogenesis and gene therapy approaches, immunotherapy emerges as a meaningful and feasible treatment approach for inducing long-term survival in at least a subpopulation of these patients. Setting up immunotherapy for an inherent immunosuppressive tumor located in an immune-privileged environment requires integration of a lot of scientific input and knowledge of both tumor immunology and neuro-oncology. The field of immunotherapy is moving into the direction of active specific immunotherapy using autologous dendritic cells (DCs) as vehicle for immunization. In the translational research program of the authors, the whole cascade from bench to bed to bench of active specific immunotherapy for malignant glioma is covered, including proof of principle experiments to demonstrate immunogenicity of patient-derived mature DCs loaded with autologous tumor lysate, preclinical in vivo experiments in a murine orthotopic glioma model, early phase I/II clinical trials for relapsing patients, a phase II trial for patients with newly diagnosed glioblastoma (GBM) for whom immunotherapy is integrated in the current multimodal treatment, and laboratory analyses of patient samples. The strategies and results of this program are discussed in the light of the internationally available scientific literature in this fast-moving field of basic science and translational clinical research.

Two phase II trials of temozolomide with interferon-alpha2b (pegylated and non-pegylated) in patients with recurrent glioblastoma multiforme

BACKGROUND

Because of the poor outcomes for patients with recurrent glioblastoma multiforme (GBM), and some laboratory and clinical evidence of efficacy using interferon in GBM, we assessed the toxicity and efficacy of temozolomide (TMZ) combined with either short-acting (IFN) or long-acting (pegylated) interferon alpha2b (PEG) in two single-arm phase II studies, and compared the results to 6-month progression-free survival (PFS-6) data from historical controls.

METHODS

Two single-arm phase II studies were carried out in adults with GBM. Patients were treated with the standard regimen of TMZ (150-200 mg m(-2) per day x 5 days every month) combined with either 4 million units per m(2) subcutaneously (SQ) three times weekly of IFN or 0.5 microg kg(-1) SQ weekly of PEG. Physical exams and imaging evaluations were carried out every 8 weeks.

RESULTS

On the IFN study, 34 adults (74% men) were enrolled, and 29 adults (55% men) on the PEG study; median Karnofsky performance status was 80 and 90 for the IFN and PEG studies, respectively. Grade 3 or 4 toxicities were common, leucopoenia and thrombocytopoenia occurring in 35-38% and 18-21% of patients, respectively. Grade 3 or 4 fatigue occurred in 18% of patients on both studies. Lymphopoenia was infrequent. PFS-6 was 31% for 29 evaluable patients in the IFN study and 38% for 26 evaluable patients in the PEG study.

CONCLUSION

In recurrent GBM patients, both studies of standard dose TMZ with either IFN or PEG showed improved efficacy when compared to historical controls, or reports using TMZ alone. Even though the TMZ+PEG study met criteria for further study, the results of both of these studies must be considered in light of the standard of care (TMZ plus radiotherapy) for newly diagnosed GBM, which has evolved since the inception of these studies. Despite the results of the current studies being eclipsed by the new GBM standard of care, these results can still inform the development of newer approaches for GBM, either in an earlier, upfront setting, or by extrapolation of the results and consideration of the use of PEG or IFN in conjunction with other antiglioma strategies.

Immunotherapy for malignant gliomas: emphasis on strategies of active specific immunotherapy using autologous dendritic cells

REVIEW

In this review, we discuss immunotherapy for malignant gliomas.

EMPHASIS

The emphasis is on the novel strategy of active specific immunotherapy using dendritic cells as antigen-presenting cells, especially its theoretical concepts and advantages, specific requirements, critical issues, pre-clinical and early clinical experience. Dendritic cell vaccination is situated in the diversity of other immunotherapeutical approaches.

FURTHER DISCUSSION

Future directions, challenges, and drawbacks will be discussed.

The neurosurgeon as local oncologist: cellular and molecular neurosurgery in malignant glioma therapy

Malignant gliomas are among the most challenging of all cancers to treat successfully, being characterized not only by aggressive proliferation and expansion but also by inexorable tumor invasion into distant brain tissue. Although considerable progress has been made in the treatment of these tumors with combinations of surgery, radiotherapy, and chemotherapy, these efforts have not been curative. Neurosurgeons as oncologists have increasingly turned their attention to therapies on a molecular scale. Of particular interest to neurosurgeons is the ability to deliver therapy locally to the tumor site or to take advantage of existing immunological mediators, enhancing drug concentrations or therapeutic cell numbers while bypassing the blood-brain barrier to maximize efficacy and minimize systemic toxicity. Exciting local-therapy approaches have been proposed for these devastating tumors. In this review, we discuss the potential applications of bioreactors, neural stem cells, immunotherapies, biodegradable polymers, and convection-enhanced drug delivery in the treatment of malignant gliomas. These approaches are at different stages of readiness for application in clinical neurosurgery, and their eventual effects on the morbidity and mortality rates of gliomas among human patients are difficult to ascertain from successes in animal models. Nevertheless, we are entering an exciting era of "nanoneurosurgery," in which molecular therapies such as those discussed here may routinely complement existing surgical, radiological, and chemotherapeutic approaches to the treatment of neuro-oncological disease. The potential to deploy any of a number of eloquently devised molecular therapies may provide renewed hope for neurosurgeons treating malignant gliomas.

Second-generation interferons for cancer: clinical targets

IFNs were the first new therapeutic products resulting from recombinant DNA technology. IFNs were also the first human proteins effective in cancer treatment. There is however much to be discovered which will lead to new clinical applications. Areas which represent major research challenges for full understanding and application of the IFN system are: (i) the diversity of the IFN family; (ii) the role of induction; (iii) molecular mechanism of action; (iv) cellular modulatory effects; (v) advantages of combinations, and (vi) identification of new therapeutic indications. This review will emphasize the diversity of the IFN family and chemical modifications which will result in second-generation IFNs. Pre-clinical and clinical findings form the basis for new therapeutic directions in chronic myelogenous leukemia, lymphomas, myelomas, melanoma, urologic malignancies, primary brain tumors, and ovarian carcinoma.

Glioma immunology and immunotherapy

OBJECTIVE

Despite advances in conventional therapy, the prognosis for most glioma patients remains dismal. This has prompted an intensive search for effective treatment alternatives. Immunotherapy, one such alternative, has long been recognized as a potentially potent cancer treatment but has been limited by an inadequate understanding of the immune system. Now, increased insight into immunology is suggesting more rational approaches to immunotherapy. In this article, we explore key aspects of modern immunology and discuss their implications for glioma therapy.

METHODS

A thorough literature review of glioma immunology and immunotherapy was undertaken to inquire into the basic immunology, central nervous system immunology, glioma immunobiology, standard glioma immunotherapy, and recent immunotherapeutic advances in glioma treatment.

RESULTS

Although gliomas express tumor-associated antigens and appear potentially sensitive to immune responses, many factors work together to inhibit antiglioma immunity. Not surprisingly, most clinical attempts at glioma immunotherapy have met with little success to date. However, novel immunostimulatory strategies, such as immunogene therapy, directed cytokine delivery, and dendritic cell manipulation, have recently yielded dramatic preclinical results in glioma models. This suggests that glioma-derived immunosuppression can be overcome.

CONCLUSION

Modern molecular biology and immunology techniques have yielded a wealth of new data about glioma immunobiology. Armed with this information, many investigators have proposed novel means to stimulate antiglioma immune responses. Although definitive clinical results remain to be seen, the current renaissance in glioma immunology and immunotherapy shows great promise for the future.

High dose oral tamoxifen and subcutaneous interferon alpha-2a for recurrent glioma

Chemotherapeutic regimens in present use for recurrent glioma have substantial toxicity. Activity against recurrent gliomas has been reported for both tamoxifen and interferon alpha, agents that have more acceptable toxicity profiles and that can be administered in an outpatient setting. We tested the efficacy and toxicity of the combination of high-dose tamoxifen and interferon alpha in adults with recurrent glioma in a phase II trial. Eligible patients had radiographically measurable recurrent gliomas of any grade after initial radiation therapy. Interferon-alpha [6 x 10(6) U subcutaneously three times per week] and tamoxifen (240 mg/m2/day orally) were administered continuously. Treatment response was assessed at 6 week intervals using clinical and radiographic criteria. Eighteen patients (11 males and 7 females) were enrolled. Median age was 41 years (range 23-61 years). All patients had gliomas that progressed after radiation therapy and nitrosourea chemotherapy. The histologic diagnosis of the original tumor was glioblastoma multiforme in 8 patients, anaplastic astrocytoma in 5 patients, astrocytoma in 4 patients and mixed malignant glioma in 1 patient. Reversible moderate to severe neurological toxicity manifested by dizziness and unsteady gait was seen at tamoxifen doses of 240 mg/m2/day. Although the initial tamoxifen dose was reduced to 120 mg/m2/day, moderate neurotoxicity was noted at this dose as well and the trial was closed early. The combination of oral tamoxifen (120 to 240 mg/m2/day) and subcutaneous interferon-alpha [6 x 10(6) U three times per week] was associated with significant neurotoxicity in this group of recurrent glioma patients, resulting in early study closure. Of 16 evaluable patients, 12 had progressive disease after one cycle of treatment, 3 had stable disease, and there was one minor response. Gradual dose escalation may be required if similar patients are to be treated with high dose tamoxifen in conjunction with interferon.

The effects of local and systemic interferon beta (Fiblaferon) on supratentorial malignant cerebral glioma--a phase II study

In contrast to the highly promising and, with rates up to 40%, surprisingly high response rates of malignant supratentorial brain gliomas to post-operative adjuvant IFN beta therapy, we were unable to demonstrate any definite anti-proliferative, anti-tumor or immunomodulatory effects of interferon in a phase II study in 13 patients. We used high doses of an IFN beta, Fiblaferon, whose potency was repeatedly confirmed by pharmacokinetic investigations, for local and systemic administration, and the times of administration were those used in the Japanese comparative studies. The side effects observed proved to be related to the amount of IFN beta administered and its duration in our patients as well. In this context, the neurotoxic disturbances require particular attention. These resolved completely after discontinuation of IFN treatment, as do the haematological and liver enzyme disturbances after suspension of medication. We did not observe any improvement in the post-operative quality of life, nor, above all, any improvement in long-term prognosis resulting from a prolonged tumor-free remission period and prolongation of the actual post-operative survival time.

Local immunotherapy (beta-IFN) and systemic chemotherapy in primary glial tumors

Dosage and schedules for the treatment of malignant glial tumors using IFN (interferon) are still uncertain and controversial. In this study we give the preliminary results of treatment in 28 patients with glioblastoma multiforme (GBM). 6 patients were treated with local injection of beta-IFN through an Ommaya reservoir; 4 patients with beta-IFN followed by systemic chemotherapy (Cisplatin + Etoposide), and 18 patients with chemotherapy only. Two end points were evaluated: 1) Whether or not the patients responded to treatment. 2) Length of Time to Tumor Progression (TTP) after surgery. We found that IFN alone was ineffective. Results were improved when local immunotherapy was associated with systemic chemotherapy. New drugs and investigation of possible pharmacological synergism are needed.

Distribution of mouse interferon-beta in normal and brain tumour-bearing mice

The distribution of 125I-labelled recombinant mouse interferon-beta (rMuIFN-beta) in normal and glioma (203 glioma) bearing mice was studied by radioassay and macro-autoradiography at 15 and 30 min after a single intravenous injection. The level of rMuIFN-beta in the spleen was about 20-fold higher than in serum. Concentrations higher than the serum level was detected in the lung, liver and kidney. The concentration of rMuIFN-beta in the brain was 8% of the serum level and the concentration in the glioma 30 min after administration was about 10-fold higher than in normal mouse brain. Macro-autoradiographic study demonstrated a wide distribution range and selective uptake in glioma tissue. Furthermore, we found that mouse gliomas were sensitive to mouse IFN-beta. Our findings demonstrate that in the mouse glioma model, intravenously administered interferon reaches the tumour.

Immunobiology of brain tumors

In summary, many actual interactions between tumors in the CNS and the immune system have been demonstrated. The normal brain does not possess a lymphatic system and is partially hidden from the systemic immune system by the BBB, furthermore brain cells do not express MHC antigens which are necessary for the initiation of an immune response. In pathological conditions however, immunocompetent cells may find their way through transformed endothelial cells. Microglia and astrocytes may function as antigen presenting cells. Glioma cells when stimulated by cytokines such as IFN gamma can be induced to express MHC class I and class II antigens, thus making them more susceptible to an immune attack. In addition glioma cells are capable of secreting several cytokines including IL 1, IL 3 and IL 6 also involved in the generation of an immune response. Indeed, a functional analysis of lymphocytes infiltrating gliomas has revealed the accumulation at the tumor site of cytotoxic T lymphocytes as well as NK cells. However host-immune responses against gliomas seem to be weak in comparison to other cancers. Glioma cells are known to secrete TGF beta 2 and PGE 2 which may in part be responsible for this lack of immune response, thus shielding themselves from immune attack. In order to be recognized by the immune system the tumor cells must express TAA in addition to MHC antigens, and such TAA have been identified by MAbs. These MAbs can be used for "targeted" therapy when coupled to toxic agents or radionuclides. Preclinical studies have shown that, after intravenous or intracarotid injection, there is specific accumulation of the MAb in the tumor but in insufficient amounts for therapeutic use. The relatively small amount of MAb binding to the tumor in vivo can be due to several factors: not all the cells in a single tumor express a given tumor-associated antigens, the MAb may have a low affinity for the antigen, the BBB may hinder the passage of the MAb. Attempts have been made to overcome these drawbacks by opening the BBB for example. In addition MAbs can readily be used for the treatment of carcinomatous meningitis. There has been little success in the development of immunotherapy with IFN beta 1 and even less with adoptive immunotherapy using LAK cells plus IL 2. TIL as well as LAK cells can be expanded in vitro with IL2 and it is feasible to reinject these cells into the tumor site.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of interferon-gamma and tumor necrosis factor-alpha on clonogenic growth of cell lines and primary cultures from human gliomas and brain metastases

In this study we tested the effect of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha) and a combination of these immunotherapeutics on clonogenic growth of cell lines and primary cultures of malignant human brain tumors. Out of 29 primary cultures studied, 5 were inhibited 50% or more by IFN-gamma (10 ng/ml), 6 were inhibited 50% or more by TNF-alpha (10 ng/ml) and 14 were inhibited 50% or more by a combination of IFN-gamma (10 ng/ml) and TNF-alpha (10 ng/ml). The doses of the immunotherapeutics used in this in vitro study are achievable in serum after intravenous administration of IFN-gamma and TNF-alpha without causing unacceptable side effects. We believe that some glioma patients and some patients with brain metastases will benefit from receiving treatment with IFN-gamma, TNF-alpha or a combination of these immunotherapeutics. The patients should be selected for treatment with these immunotherapeutics according to in vitro sensitivity results.

Cerebral interferon entry in mice after osmotic alteration of blood-brain barrier

Systemically administered interferon (IFN) is not readily detected in the central nervous system (CNS) due to the presence of the blood-brain barrier (BBB). A method of osmotic BBB alteration in a mouse model was established in this laboratory. IFN's entry into the normal and osmotically altered brain after its intracarotid injection was investigated. Significant IFN levels (100-1,000 units) in the brain can be achieved by this method. The highest IFN activity was found in the brain hemisphere ipsilateral to the injection site within 20 min to 1 h after injection. IFN activity in the brain was detectable up to 4 h. Animals injected in this manner with murine IFN-alpha/beta (MuIFN-alpha/beta) and observed for a 6-month time interval showed no signs of neurological dysfunctions and resumed their normal activities. The therapeutic value of this method will be tested in a murine model of malignant glioma.

Intratumoural and intraventricular human lymphoblastoid alpha interferon (HLBI) for treatment of glioblastoma multiforme

A series of ten patients with glioblastoma multiforme were treated with human lymphoblastoid alpha interferon (HLBI) as a single therapy after partial surgical resection (5 cases) or stereotactic biopsy (5 cases). Treatment consisted of intratumoural administration of HLBI (15 x 16(6) IU) every month (8 cases) or in the continuous intraventricular infusion of HLBI (1.8 x 10(6) IU daily) in 15-day cycles (2 cases) until rapid growing of the tumour and important neurological deterioration. The treatments were well tolerated. As judged from data from control groups, the patients demonstrated no improvement in mean survival time and follow-up CT-scan showed rapid progression of the tumour in all cases.

Systemic gamma-interferon therapy for recurrent gliomas

Recombinant gamma-interferon (2 mg/sq m) was administered intravenously twice weekly in 8-week courses to 14 patients with recurrent gliomas. Computerized tomography (CT) evidence of response was seen in only one patient, and stabilization for 12 to 86 weeks was recorded in three. This was a disappointing result, particularly in a series of patients with relatively small initial tumor volumes (less than 50 cu mm on enhanced CT) and Karnofsky functional ratings of 70 or higher. In addition, several instances of toxicity potentially attributable to gamma-interferon were observed.

Antitumour effect of interferon combined with hyperthermia against experimental brain tumour

Antiproliferative activity of recombinant murine interferon-beta (Rec-MuIFN-beta) combined with hyperthermia against Rous sarcoma virus-induced mouse malignant glioma (RSV glioma) was investigated both in vitro and in vivo. In vitro, the antiproliferative activity of Rec-MuIFN-beta was enhanced by incubation at elevated temperatures (40 degrees and 43 degrees C). In vivo, combined therapy of Rec-MuIFN-beta treatment and local tumour hyperthermia (43 degrees C) exerted a greater antitumour effect against transplanted RSV glioma in C3H/He mice than either treatment alone, especially when Rec-MuIFN-beta was administered intratumourally. Subsequently, in order to probe the mechanism of enhanced antiproliferative activity, the production of prostaglandin E2 (PGE2) and 2', 5'-oligoadenylate synthetase (2-5A synthetase) in the culture medium of RSV glioma cells was measured. Rec-MuIFN-beta treatment resulted in a significantly greater PGE2 and 2-5A synthetase production at 43 degrees C than at 37 degrees C.

Does successful interferon treatment of tumor patients require life-long treatment?

Case histories of 5 tumor patients treated with natural leukocyte interferon-alpha (IFN-alpha) are presented. One patient with juvenile laryngeal papillomatosis responded well to interferon treatment, but the disease recurred when therapy was withdrawn. Upon reinstitution of treatment, the patient once again responded well. Another patient with myelomatosis also responded well to interferon therapy and in this case, too, the tumor recurred when interferon treatment was withdrawn. Reinstitution of interferon therapy was, however, unsuccessful. One patient with generalized giant cell tumor of bone responded with regression after more than 5 years of interferon treatment. Another patient with pulmonary osteosarcoma metastases, having received irradiation and interferon combination therapy followed by sole interferon treatment, responded well with a lasting stationary radiogram after 6 years of interferon treatment. One patient with malignant glioma, showing signs of tumor growth during the first few months of interferon therapy, eventually responded, and became disease-free after 6 years. The latter 3 patients are continuously receiving interferon therapy although more than 5 years have elapsed since their interferon therapy was initiated. It is suggested that interferon therapy for malignant tumors be given for life (or to progression of disease) in responding patients. Such a concept entails biological implications for interferon therapy in general and for antitumor action of interferons in particular. Other possible clinical schedules should only be constructed within the framework of controlled clinical trials.

The antitumor effects of interferon

Interferons show antitumor activity in patients with various malignancies. The mechanism(s) of the antitumor effects are not altogether clear. In one experimental animal model discussed herein, mice were injected with Friend erythroleukemia cells and treated with mouse interferon alpha/beta. The results suggest that interferon does not act directly on the tumor cells but acts via host mechanisms that are still ill defined.

Mitogen-activated lymphocytes of normals and glioma patients produce factors with anti-glioblastoma activity in vitro

Human glioblastoma cell lines showed profound suppression of both DNA and RNA synthesis when exposed to supernatants (SNs) of mitogen-activated blood mononuclear cells. Cloning efficiency of these glioma cells also decreased 10- to 500-fold. In monolayer cultures, growth inhibition was evident within 12 h of adding SN and peaked at 24 h. A decrease in absolute cell number was evident by 72 h. The inhibitory effect of SNs, however, was not permanent as more cells entered S-phase when SN-treated cultures were refed with fresh medium (without SN). The factor(s) responsible for this inhibitory activity was a product of lymphocytes and was produced in comparable amounts by cells of normal blood donors and patients with glioma. The compromised immunological status of glioblastoma patients did not influence their capacity to produce cytostatic lymphokines.

Phase II trial of interferon-beta for treatment of recurrent glioblastoma multiforme

Twelve patients were admitted to a Phase II study on the treatment of recurrent glioblastoma multiforme with interferon-beta (IFN-beta). All patients had previously undergone craniotomy and received a standard course of radiation therapy. Recurrence was inferred from enlargement of the lesion on computerized tomography (CT) scanning and in each case was confirmed by CT-guided stereotaxic biopsy. Treatment consisted of combined intravenous (10 X 10(6) IU/day) and intratumoral (1 X 10(6) IU every other day) administration of IFN-beta over three 10-day cycles. This regimen was well tolerated, with toxicity requiring temporary dose modifications in five patients. As judged from data from historical cases, however, the patients admitted to this study demonstrated no clear improvement in mean survival time. The findings of this study also emphasize the importance of distinguishing between radiation necrosis and tumor recurrence.

Immunobiology of primary intracranial tumors. Part 10: Therapeutic efficacy of interferon in the treatment of recurrent gliomas

Human lymphoblastoid alpha-interferon was administered intravenously or intramuscularly to 19 patients with recurrent gliomas. Each patient had previously undergone surgery and radiation therapy. The treatment course consisted of 8 weeks of therapy with an escalating daily dosage and number of days of treatment per week to a total dose of 900 X 10(6) U/sq m. Response to treatment was determined by serial computerized tomography (CT) scans. Seven of the 17 evaluable patients were determined to be treatment responders at 12 weeks (1 month after completion of treatment), and the other 10 patients exhibited tumor progression during this period. Median survival time was 511 days for the responders versus 147 days for the non-responding patients. Interferon appears to be efficacious in the treatment of recurrent anaplastic gliomas as defined by CT brain scan responses following therapy.

Interferon as adjuvant therapy with initial radiotherapy of patients with anaplastic gliomas

In a group of nine patients with anaplastic gliomas, survival following surgery and treatment with interferon and radiotherapy was comparable to survival for a matched group of patients treated with BCNU and radiotherapy following surgery.

Single agent therapy of interferon for brain tumours: correlation between natural killer activity and clinical course

The anti-tumour effect of mouse interferon (IFN) on an intracranially transplanted 203-glioma in C 57BL mice and the natural killer (NK) activity of spleen cells were studied. As a clinical trial, five patients with glioblastomas were treated with human fibroblast IFN and the anti-tumour effect of IFN and the NK activity of peripheral blood lymphocytes were also studied. The NK activity increased after the beginning of IFN therapy but there was no remarkable anti-tumour effect of IFN in both mouse and human studies. There was no marked correlation between the increased NK activity and the anti-tumour effect of IFN in this study.

Clinical effect of interferon in malignant brain tumours

Phase I and phase II clinical studies of interferon (IFN) were conducted in malignant brain tumours (47 cases of glioblastoma, medulloblastoma and others) using three preparations of the drug. The drug was administered daily in doses 3.0 - 9.0 X 10(6) I.U. locally or intravenously (beta-type) or intramuscularly (alpha-type). The administration was continued as many days as possible, eight weeks being the shortest period. The efficacy of the therapy was assessed mainly by the CT findings (computed volume of the tumour). As for efficacy against glioblastomas, the highest effectiveness rate (40%) was obtained with Human Fibroblast IFN (HFIF) (beta-type) (Toray) (one case of complete remission and seven cases of partial remission out of 20 cases) as compared to Human Lymphoblastoid IFN (HLBI) (alpha a-type) (Wellcome) (one case of partial remission out of three cases) and recombinant IFN (rIFN-alpha A) (alpha-type) (Roche) (two cases of partial remission out of nine cases). The high rate of responsiveness of HFIF seems to be largely attributable to the local, rather than systemic, administration of the drug. Our pharmacokinetic study revealed that, by means of intrathecal administration a much higher IFN titre was detected in the cerebrospinal fluid, while by intravenous or intramuscular route, the IFN titre in the CSF was undetectably low. The generally lower incidence of side-effects with HFIF compared to other preparations was also largely ascribable to the route of administration. IFN therapy in combination with radiotherapy and/or chemotherapy should also be investigated.