Interferons: anti-neoplastic drugs?

Interferon Signaling in Estrogen Receptor-positive Breast Cancer: A Revitalized Topic

Cancer immunology is the most rapidly expanding field in cancer research, with the importance of immunity in cancer pathogenesis now well accepted including in the endocrine-related cancers. The immune system plays an essential role in the development of ductal and luminal epithelial differentiation in the mammary gland. Originally identified as evolutionarily conserved antipathogen cytokines, interferons (IFNs) have shown important immune-modulatory and antineoplastic properties when administered to patients with various types of cancer, including breast cancer. Recent studies have drawn attention to the role of tumor- and stromal-infiltrating lymphocytes in dictating therapy response and outcome of breast cancer patients, which, however, is highly dependent on the breast cancer subtype. The emerging role of tumor cell-inherent IFN signaling in the subtype-defined tumor microenvironment could influence therapy response with protumor activities in breast cancer. Here we review evidence with new insights into tumor cell-intrinsic and tumor microenvironment-derived IFN signaling, and the crosstalk of IFN signaling with key signaling pathways in estrogen receptor-positive (ER+) breast cancer. We also discuss clinical implications and opportunities exploiting IFN signaling to treat advanced ER+ breast cancer.

Interferon signaling in cancer. Non-canonical pathways and control of intracellular immune checkpoints

The interferons (IFNs) are cytokines with important antineoplastic and immune modulatory effects. These cytokines have been conserved through evolution as important elements of the immune surveillance against cancer. Despite this, defining their precise and specific roles in the generation of antitumor responses remains challenging. Emerging evidence suggests the existence of previously unknown roles for IFNs in the control of the immune response against cancer that may redefine our understanding on how these cytokines function. Beyond the engagement of classical JAK-STAT signaling pathways that promote transcription and expression of gene products, the IFNs engage multiple other signaling cascades to generate products that mediate biological responses and outcomes. There is recent emerging evidence indicating that IFNs control the expression of both traditional immune checkpoints like the PD-L1/PD1 axis, but also less well understood "intracellular" immune checkpoints whose targeting may define new approaches for the treatment of malignancies.

Cancer immunotherapy: potential involvement of mediators

The description of a cell-free soluble anti-tumour factor by Carswell et al. in 1975 (Proc Natl Acad Sci USA, 72: 3666–3670) was followed by a long series of experimental and clinical investigations into the role of cell-free mediators in cancer immunotherapy. These investigations included research on the effects of macrophage–derived eicosanoids (cycloxygenase and lipoxygenase derivates of arachidonic acid) and of monokines such as tumour necrosis factor-α, interleukin-1 and granulocyte–monocyte–macrophage–colony stimulating factor) and of lymphocyte products: interleukins and interferons. The investigations yielded information on the effects of various factors on macrophage and T-cell activation in vitro, determination of direct anti-tumour properties on animal and human tumour cells in vitro and on therapeutic effectiveness in tumour-bearing individuals either alone or in combination with other therapeutic factors and their production by tumour cells. During recent years much effort has been dedicated towards the use of the tumour cells transfected with cytokine genes in the preparation of cancer vaccines. Cycloxygenase products (prostaglandins) were usually assumed to inhibit expression of anti-tumour activity by macrophages and an increase in their production in cancer patients was considered as a poor prognostic index. Lipoxygenase (leukotrienes) products were assumed to exhibit antitumour activity and to induce production of IL-1 by macrophages. Interleukins 2, 4, 6, 7, 12 and the interferons were extensively tested for their therapeutic effectiveness in experimental tumour models and in cancer clinical trials. The general conclusion on the use of cell-free mediators for cancer immunotherapy is that much still has to be done in order to assure effective and reproducible therapeutic effectiveness for routine use in the treatment of human neoplasia.

Interferon therapy in multiple myeloma

A woman with multiple myeloma relapsed after 6 years of satisfactory tumor control with melphalan therapy. When progression then occurred, she was given exogenous human leukocyte interferon, 3 x 10(6) reference units twice daily i.m., as the sole therapy. Side-effects of the interferon therapy consisted of fever reactions and thrombocytopenia. One month after the initiation of interferon therapy there was 1) improvement of general health with less pain and tiredness, 2) reduction of the M-component, IgG-lambda, in the serum, and 3) a reduced plasma cell concentration in the bone marrow. After 5 months of interferon therapy tumor progression occurred despite continuous interferon treatment. At the same time, the tumor cells were less sensitive to interferon in in vitro tests than prior to interferon therapy. It is suggested that interferon therapy should be given as initial treatment to a few patients with multiple myeloma in a phase I trial.

Immune reactions and long-term therapy with human leukocyte interferon

Twenty patients with osteosarcoma were treated with exogenous human leukocyte interferon for periods ranging from 6 to 18 months. Eleven of them remained free from detectable tumour growth during this treatment. Blood samples from all patients were tested for antibodies against interferon and against impurities in the interferon preparations. No patient developed detectable levels of neutralizing antibodies against interferon. All patients formed antibodies against contaminants in the concentrated crude interferon and the partially purified interferon preparation which had been used for treatment.

Interferon therapy in recurrent renal carcinoma

Seven patients with recurrent renal carcinoma, who had previously been treated with progesterone and vinblastine for progressive disease, were treated with human leukocyte interferon (HuIFN alpha). Five patients received daily escalating i.m. IFN doses from 4 X 10 up to 16 X 10(6) U during a minimum of 4 weeks, while two patients received intralesional IFN, 20 X 10(6) U/dose. No serious side-effects were observed. No tumor response was found in any of these patients.

Potential of interferon-alpha in solid tumours: part 1

Interferon-alpha (IFNalpha) is a pleiotropic cytokine with direct and indirect antitumour effects. These include prolongation of the cell cycle time of malignant cells, inhibition of biosynthetic enzymes and apoptosis, interaction with other cytokines, and immunomodulatory and antiangiogenic effects. The first clinical trials in solid tumours used crude preparations of natural IFNalpha and demonstrated that tumour regressions in solid tumours and haematological malignancies were possible. Since the advent of genetic engineering technology, recombinant (r) IFNalpha has been widely evaluated in solid tumours. This review discusses the use and potential of rIFNalpha in solid tumours; the first part focuses on malignant melanoma and metastatic renal cell carcinoma (RCC). In the adjuvant treatment of malignant melanoma, rIFNalpha has been tested in randomised trials in more than 6000 patients. High-dosage IFNalpha (> or =10MU) prolongs disease-free survival (DFS) but not overall survival (OS). Low-dosage IFNalpha (< or =3MU) has not been shown to prolong DFS or OS, and current data do not support its use outside clinical trials. The latest United Kingdom Co-ordinating Committee on Cancer Research meta-analysis of ten randomised trials that used adjuvant rIFNalpha has shown that there is a benefit in DFS but not OS. No conclusions can be reached for intermediate-dosage IFNalpha (5 to 10MU) until the mature results of the European Organization for Research and Treatment of Cancer (EORTC) study 18952 are available. In RCC, current evidence does not support the use of adjuvant IFNalpha. In metastatic malignant melanoma and RCC, reported response rates to rIFNalpha are approximately 15%. In a minority of responding patients, however, these responses can be long-standing. In metastatic malignant melanoma, IFNalpha combined with other cytotoxic agents with or without interleukin-2 has achieved high response rates but has not improved survival. In metastatic RCC, intermediate dosages of rIFNalpha should be used and therapy should probably be prolonged (>12 months); response depends on prognostic factors such as good performance status, whereas survival is affected by factors such as low tumour burden. Nephrectomy should therefore be considered in patients with good performance status prior to IFNalpha immunotherapy in advanced RCC, even in patients with metastatic disease. The toxicity of high-dosage IFNalpha and the lack of definite benefit on OS with high- or low-dosage IFNalpha do not support its use outside clinical trials. Data from the ongoing US Intergroup studies, the ongoing EORTC 18991 study (long-term therapy with pegylated IFNalpha) and mature data from EORTC 18952 (intermediate-dosage IFNalpha) will help establish the role of IFNalpha as adjuvant therapy in malignant melanoma.

Interferon as adjunctive treatment for non-metastatic renal cell carcinoma

OBJECTIVE

To investigate the effect of recombinant alpha 2b-interferon therapy on natural killer (NK) activity and antibody-dependent cell-mediated cytotoxicity (ADCC) in the peripheral blood in patients with renal cell carcinoma who had undergone radical nephrectomy.

PATIENTS AND METHODS

Between January 1988 and June 1989, 20 patients (14 men and six women, mean age 59 years, range 43-80) received interferon (IFN) therapy following radical nephrectomy for renal cell carcinoma. Thirteen patients had stage I disease, one had stage II and six had stage III; none had metastases.

RESULTS

There was a significant increase in NK activity at 5 and 7 months after starting IFN therapy but there was no increase in ADCC.

CONCLUSIONS

Low doses of IFN administered long-term increased NK activity in patients with renal cell carcinoma. This finding should be helpful in designating protocols for randomized studies of post-operative IFN administration as adjuvant therapy.

The role of cytokines in oncology

The availability of sufficient quantities of recombinant human cytokines and promising preclinical data have led to their introduction into clinical trials. Cytokines have potential as new therapeutic agents in a variety of hematological disorders as well as in solid tumors. Only a few of the still increasing number of these glycoprotein hormones have been studied in humans so far, either as single agents or in combination with chemotherapy and other cytokines. Their clinical effects, beneficial role in supportive care, and use in the treatment of certain cancer patients are reviewed.

Osteosarcoma

Osteosarcoma is the most common bone tumor of children and adolescents. The peak incidence of the disease is in the 15 to 19 year age group. The disease is more commonly seen in males than females. While several factors, including exposure to radiation, genetic disorders such as retinoblastoma, and high rate of bone growth, have been associated with osteosarcoma, in most cases no definite etiology can be established. Osteosarcoma usually originates in the metaphyseal region of long bones and extends through the cortex, causing varying degrees of bone destruction and expansion of periosteum. The radiographic appearance caused by this process is often referred to as "sun burst" sign. Positive diagnosis of osteosarcoma is made by histopathology. The histopathological classification of osteosarcoma can also predict the degree of aggressive behavior of this tumor and thus has prognostic significance. Surgery, including amputation or limb-salvage procedure, is the mainstay of treatment of osteosarcoma. It is now unequivocally established that adjuvant chemotherapy will prolong the survival of patients with this disease. Chemotherapy agents often used include platinum derivates, methotrexate, vincristine, cyclophosphamide, adriamycin, actinomycin D, bleomycin and DTIC. Depending on surgical decision, these agents can be used prior to or after the operation. Immediate fitting with prosthesis and provision of appropriate medical and psychological support in the care of these patients is essential.

A first case of complete remission of beta-interferon sensitive adult T-cell leukemia

A case of complete remission of adult T-cell leukemia (ATL) induced by beta-interferon is reported. A 46-year-old male was diagnosed as ATL because of the increased number of ATL cells with deeply indented and lobulated nuclei in the peripheral blood, accompanied by elevated values of the lactic dehydrogenase, the alkaline phosphatase, and the calcium in the serum. The result of the cell surface marker analysis of peripheral blood lymphocytes was compatible with ATL and anti-ATL associated antibody (ATLA) was positive. The integration of proviral deoxyribonucleic acid (DNA) of human T-cell leukemia virus type I(HTLV-I) was proved in the peripheral blood lymphocytes using Southern blot hybridization. Since an ordinal chemotherapy was not so effective for this patient, he was treated with 1.8 X 10(7) units of recombinant beta-interferon (beta-IFN) per day for 7 days as one course. After 5 courses of treatment, a markedly favorable response was recognized, and he achieved complete remission. A lower dose of beta-IFN (9 X 10(6) units per day for 3 days as one course, one or two courses per month) has been continued and he has still been in a complete remission state for 10 months. It is concluded that beta-IFN should be used to treat ATL.

Interferon treatment of human stomach and breast carcinoma xenografts in nude mice

Comparative effects of natural and recombinant interferons (IFNs)-alpha and -beta on xenografted human gastric and breast carcinoma lines in nude mice were studied. The lines were sensitive to IFNs. The breast carcinoma lines were more sensitive than the gastric carcinoma lines to IFNs. Natural IFN-beta was more effective than the other three IFNs on the gastric carcinoma lines. One breast carcinoma line was more sensitive to IFN-alpha whereas the other was more sensitive to IFN-beta. Large doses and frequent injections of IFNs were necessary for optimal effectiveness.

Treatment of multiple myeloma with recombinant interferon alfa-2a

A Phase II study of interferon alfa-2a was conducted in 64 patients with multiple myeloma (42 IgG, 16 IgA, 5 Bence-Jones type, and 1 IgD) in a multi-institutional cooperative trial. Partial remission was obtained in 10 (21.3%) of 47 evaluable patients, and minor responses in 5 (10.6%) of 47. Remission was reached at 22 to 89 days (median, 29 days) after the initiation of interferon alfa-2a and lasted 4 to 55 weeks (median, 8 weeks). Side effects were noted in more than two-thirds of patients, and included fever (58%), malaise (20%), anorexia (52%), nausea-vomiting (26%), lethargy (2%), and myelosuppression (56%). They were all reversible on discontinuation of interferon alfa-2a. Antibody to interferon alfa-2a was detected in 1 of 20 patients tested during the course of treatment. Thus, interferon alfa-2a was effective in multiple myeloma, producing unequivocal response in 21.3% of patients without unacceptable side effects.

The in vitro effect of leucocyte alpha-interferon on human myeloma cells in a semisolid agar culture system

73 bone marrow samples from a total of 50 patients with multiple myeloma (MM) were tested for interferon (IFN) sensitivity in the human tumour colony assay (HTCA). 16 evaluable samples were obtained from untreated patients, 10 from patients during melphalan and prednisone treatment and 6 from patients on IFN treatment or after withdrawal of IFN. The sensitivity to IFN was individually distributed between the bone marrow samples from patients of all 3 groups and a tendency towards IFN resistance could be found in serial assays from patients during MP-treatment and after IFN withdrawal. Stimulation of growth was found in 31% of the cultures, usually at lower doses of IFN (10-100 U/ml) while higher doses (400-4000 U/ml) inhibited growth in 75% of the assays.

The effect of murine interferon-alpha/beta on an established Rauscher murine leukemia virus-induced erythroleukemia in BALB/c mice

Rauscher murine leukemia virus (R-MuLV) induces a rapidly developing erythroleukemia in BALB/c mice. Previously, we have shown that mouse interferon-alpha/beta (Mu IFN-alpha/beta) applied shortly after virus inoculation efficiently inhibits the leukemic process (Hekman et al., 1981). Here we describe the effect of Mu IFN-alpha/beta on an established leukemia. Varying doses of Mu IFN-alpha/beta were injected over 3 days, starting 8 to 12 days after virus inoculation. The effect of Mu IFN-alpha/beta on the leukemic process was monitored by measuring the spleen weight, reverse transcriptase activity in the serum and, in selected experiments, by microscopic examination of sections of the spleen using standard histological and immunological staining techniques. Depending on the spleen weight at the start of its application (maximal about 450 mg), Mu IFN-alpha/beta caused a dramatic reduction in the number of virus-infected erythroleukemic cells in the spleen. Also, R-MuLV disappeared from the serum within 3 days. If Mu IFN-alpha/beta was injected into R-MuLV-infected mice with an already 10-fold enlarged spleen, it could only stop further development of leukemia. Results obtained with crude Mu IFN-alpha/beta preparations were confirmed with absolutely pure Mu IFN-beta.

The combined effect of interferon-beta and cytostatic drugs on human tumor cell lines in vitro

Three human tumor cell lines (one osteosarcoma and two neuroblastoma lines) were assessed for combined interferon-beta (IFN-beta)/chemotherapeutic drug antigrowth effect under in vitro conditions. Two different methods to measure this effect were used: colony formation in soft agar and counting of cells growing as monolayers. The cells were incubated with a chemotherapeutic drug (adriamycin, dacarbazine, actinomycin D, cis-platinum, methotrexate, VP-16-213, or vincristine) at relevant concentrations for 1 h, washed twice, and incubated with IFN-beta in concentrations ranging from 100 to 1000 IU for continuous exposure. All combinations resulted in an additive or synergistic combination effect with one exception: methotrexate/IFN-beta in the monolayer method after 1 week, a combination which was additive after 3 weeks however. The combinations VP-16-213/IFN-beta and cis-platinum/IFN-beta produced the most pronounced synergistic effects. A statistical evaluation of the null hypothesis for additivity was done. These results provide a rationale for designing clinical studies combining IFN-beta with current chemotherapeutic drugs.

Recombinant leukocyte A interferon as single agent therapy or in combination with cimetidine in patients with advanced colo-rectal carcinoma. A phase II investigation

Recombinant leukocyte A interferon used as single agent therapy (7.5 X 10(6) units/m2 three times weekly intramuscularly) showed very limited clinical efficacy in patients with advanced colo-rectal carcinoma. No objective tumour regressions were documented in 15 evaluable patients, although three patients demonstrated a stable disease status after 12 weeks of treatment. Neither were any objective tumour regressions registered in 13 patients during subsequent combined therapy with Recombinant Leukocyte A Interferon and cimetidine (1 000 mg/day orally). Two of the 3 patients maintained their stable disease status. No change in natural killer (NK) cell activity or in antibody dependent cellular cytotoxicity (ADCC) of peripheral blood mononuclear cells was seen during the two treatment periods.

Treatment of plasma cell neoplasm with recombinant leukocyte A interferon and human lymphoblastoid interferon

Thirty cases of plasma cell neoplasms (24 multiple myeloma, one plasma cell leukemia, and three primary macroglobulinemia) were treated with two kinds of highly purified alpha-interferons, recombinant human leukocyte interferon (rIFN-alpha A) (16 cases) and human lymphoblastoid interferon (HLBI) (14 cases). Partial remission (PR) was obtained in two of 16 evaluable cases treated with rIFN-alpha A and in two of 12 evaluable cases treated with HLBI. If minor response (MR) was included, responses were observed in seven (31.3%) and six (50%), respectively. Response (PR + MR) was noted in 38% of 21 previously treated patients and 71% of seven previously untreated patients. Side-effects were noted in more than two-thirds of the patients. They included fever, malaise, nausea/anorexia and myelosuppression. Thus, these two kinds of highly purified alpha-interferon were effective in plasma cell neoplasm, producing unequivocal response in 14.3% of the cases without unacceptable side-effects.

[Interferons--research, effects and importance]

Interferons are a family of proteins synthesized by the cells of higher organisms as a first reaction to viral infections, preceding the immune response. They are also involved in the regulation of the immune system and therefore included among the lymphokines. Since they had been shown to have antitumor activity in vitro and in experimental animals, they were suggested to be powerful drugs in cancer therapy.

Metastatic malignant melanoma: regression induced by combined treatment with interferon [HuIFN-alpha(Le)] and cimetidine

With the aim of potentiating the anti-tumour effect of interferon in metastatic malignant melanoma by concomitant inhibition of suppressor T cells, oral cimetidine (histamine-2 receptor antagonist) medication was added to interferon (HuIFN-alpha(Le] therapy in a series of 20 patients. While no objective tumour responses were recorded with interferon treatment alone administered intramuscularly or intratumorally, six patients had objective tumour regressions on subsequent combined therapy. Five out of eight patients with metastases confined to skin and subcutaneous tissue had complete tumour regressions while one patient with skin and lung metastases achieved an extensive partial regression of the skin tumour and a complete roentgenological regression of the lung metastasis. Three additional patients attained a stable disease status for prolonged periods of time. Histopathological examinations confirmed disappearance and/or degeneration of melanoma cells and demonstrated a marked lymphocyte infiltration in tumour sites of the patients with objective tumour regression.

Tumor growth stimulation in vitro by interferons

Interferons (IFNs) are a family of polypeptides originally identified as antiviral substances. Subsequently, other properties of interferons were recognized, including inhibition of cell proliferation, and effects on the immune response and on expression of surface antigens. In this paper we present evidence that interferons, even the highly purified cloned IFNs, can stimulate clonogenic tumor growth in vitro. Of 225 human tumor (HT) samples tested with IFN in a clonogenic assay (HTCA), 30 (13.3%) showed growth stimulation (greater than 2 S.E. above control). The phenomenon was observed most frequently with acute myeloid leukemia (6/22 samples, 27.3%), and renal (2/10, 20%) and breast cancer (4/21, 19%), but significantly less frequent in melanomas (2/34, 5.9%). As an independent assessment of proliferation, tritiated thymidine uptake by tumor cells was measured autoradiographically in 21 patients with multiple myeloma. A significant increase of the thymidine labeling index was seen in 4 (19%) of the samples. Since this growth stimulatory effect was also observed with cell lines which lack any contaminating immunoreactive cells, there is strong evidence that interferons can directly stimulate the proliferation of clonogenic tumor cells in vitro. Growth stimulation by interferons occurred preferentially with lower dosages. It is important to be cognizant of potential clinical implications of tumor growth stimulation by interferons.

Human lymphoblastoid interferon in the treatment of small cell lung cancer

Ten patients with small cell lung cancer were treated with high dose human lymphoblastoid interferon (50-100 megaunits m-2) for 5 days, followed by low dose interferon (3 megaunits m-2) for 3 weeks. At the end of treatment, and one month later, there was no evidence of either complete or partial response. The treatment produced fever, anorexia and weight loss, with transient leucopenia and thrombocytopenia; there was evidence of a non-cholestatic elevation of serum alanine aminotransferase, with clinical deterioration in the condition of three patients presenting with hyponatraemia. A transient hypocalcaemia during high dose therapy was also noted. It seems that lymphoblastoid interferon as a single agent is unlikely to have a role in the treatment of small cell lung cancer, and that its administration as employed in this study is associated with considerable toxicity.

Interferons: several questions and few answers

Interferons, which have been studied for many years as antiviral agents, are now receiving considerable attention as antitumor and immunomodulatory agents. The data to date are sufficiently interesting to warrant further studies on several fronts. Clearly, the results that have been obtained so far tend to pose more questions than they answer.

Leukocyte interferon in patients with juvenile laryngeal papillomatosis

Fourteen patients with aggressive juvenile papillomatosis were treated with systemic administration of alpha-type interferon (IFN). This initial dosage of 2 million units alpha-interferon/m2 was modified if a favorable response in the papilloma growth occurred, or if persistent drug-related side effects developed. Half of the patients showed a sustained response while on IFN, and two patients had a complete response. Persistent elevation in SGOT was the main dose-limiting toxicity, especially in infants below age seven years. All side effects subsided after the drug was discontinued. Further studies are recommended.

Cytostatic and reverse-transforming therapies of cancer - a brief review and future prospects

Cytostatic cancer therapies are defined as those which retard cancer growth by intervening selectively in the disordered control mechanisms responsible for malignant behavior, without producing direct cytotoxicity. A number of possible approaches to cytostatic therapy are now under investigation and are briefly reviewed here - cyclic AMP congeners and promoters, prostaglandin precursors, thioproline, benzaldehyde, retinoids, interferon, chalones, antineoplastons, protease inhibitors, polar solvents. Suggestions for the further development of cytostatic therapies are offered, and a role for cytostatic therapy within a broad global concept of cancer therapy is proposed.

Effects of interferon on growth rate and radiation sensitivity of cultured, human glioma cells

The influence of interferon (IFN) on the growth rate and on the radiation sensitivity of 2 human tumour cell lines was investigated. The 2 glioma cell lines (U-118 MG and U-251 MG) were continuously exposed to IFN (100 U/ml) in the culture medium. Irradiation (3 Gy) was performed either on the first day of IF treatment or on day 14 of IFN treatment. The growth delay induced by the treatments was analysed. The results indicated that IFN had an anti-proliferative effect on the 2 cell lines. However, this effect declined during the treatment and after 2 to 3 weeks of continuous IFN treatment, both cell lines had re-established their original growth rate. IFN did not seem to affect the sensitivity of the cells to radiation. Only an additive effect could be observed.

Interferon production by a human lymphoblastoid cell line (DG-75) free of the Epstein-Barr genome

A new lymphoblastoid cell line, DG-75, was investigated for its ability to produce interferon. DG-75 cells, previously shown to be free of Epstein-Barr virus genome and receptors, could be grown in submerged culture and could produce interferon in titers comparable to interferon produced by Namalva cells. The interferon produced was similar in size to the Namalva interferon as determined by gel filtration in Ultrogel AcA54. The DG-75 cells present a new source of large quantities of interferon which may be safer for human use than the Namalva interferon.

Augmentation of natural and antibody-dependent cell-mediated cytotoxicity by pure human leukocyte interferon

Augmentation of the cytolytic activity of human natural killer cells and of antibody-dependent cell-mediated cytotoxicity has been attributed to human interferons. With the purification to homogeneity of human leukocyte interferon, it became possible to test directly whether pure interferon could increase the activity of these effector cells. Treatment of purified blood mononuclear cells with pure interferon resulted in substantial increases in natural killer cell activity and in antibody-dependent cell-mediated cytotoxicity. Concentrations of 10-100 units/ml of antiviral activity were sufficient to augment appreciably natural killer cell activity.

Effect of interferon in therapy of skin and head and neck tumors

The clinical experimental model of HLI application in the therapy of skin and mucosal cancers of the head and neck has opened new prospects in HLI utilization. Based on clinical observations and research it may be concluded that HLI, if applied topically in the area of the tumor, may induce its disappearance or regression. If applied presurgically, it blocks the dispersion of neocytes during surgery. Also, HLI inhibits metastatic dissemination of malignant tumors and therefore might reduce the percentage of patients with recurrence, decreasing the chance of survival of any other primary tumor.

Management of neoplasms of the head and neck in children. 1. Benign tumors

The otolaryngologist who treats children must have knowledge of the neoplasms that can occur in childhood. Such tumors are usually mesenchymal in origin and may be benign or malignant. Diagnosis and management of the more common benign tumors are undertaken by the otolaryngologist because local excision is generally curative. The proper treatment of malignant lesions requires a more extensive, multidisciplinary team, which includes a pediatric oncologist, diagnostic and therapeutic radiologist, and pathologist, in addition to the otolaryngologist. The purposes of this paper are to outline the types of benign and malignant neoplasms that occur in childhood and to discuss current approaches to therapy.

The effect of high doses of poly(I).poly(C) induced mouse L cell interferon on Rauscher leukemia virus induced erythroleukemia in BALB/c mice

The effect of high doses of poly(I).poly(C) induced mouse L-cell interferon on the development of Rauscher murine leukemia virus (R-MuLV)-induced erythroleukemia in BALB/c mice was determined. Female mice, 4 to 5 weeks old, were infected with R-MuLV and treated with interferon every 24 h starting 6 h after virus inoculation. Under these conditions injection of 3-5 X 10(4) units of interferon caused a partial inhibition of the leukemia process. Daily application of 3 X 10(5) units completely or almost completely inhibited the erythroleukemia. After 14 days of treatment with these high doses of interferon, spleen weights of interferon-treated infected mice were comparable to those of uninfected animals which received only interferon. Also, no Rauscher cells in spleens and livers of R-MuLV-infected interferon-treated infected animals could be demonstrated and the spleen structure was well preserved in these mice. In interferon-treated infected animals no virus could be detected in the serum as judged from the absence of reverse transcriptase activity in the serum. Moreover, no virus-infected cells could be demonstrated in spleen or liver as deduced from negative immunofluorescence data using anti-p30 and anti-gp70 sera. No virions budding from spleen cell membranes were seen by electron microscopic studies. However, when interferon treatment was stopped the leukemic process was reactivated and all the mice died. In control experiments interferon caused an inhibition of red blood cell formation and a 50 to 100% enlargement of the spleen. Pharmacokinetic data showed that, after intraperitoneal inoculation, maximum amounts of interferon were present in the peripheral blood after 1-2 h. After 12-24 h almost all interferon activity had disappeared from the blood.

Current report on the interferon program at Roswell Park Memorial Institute

An overview of the interferon program at Roswell Park Memorial Institute (RPMI), is presented. This program encompasses three interrelated areas of research and new drug development: (a) basic research on purification and characterization of animal and human interferons (leukocyte, fibroblast, and immune); (b) large scale manufacture and preclinical testing of human fibroblast interferon (HFIF); and (c) clinical trials with HFIF to determine its safety of administration as well as antiviral, antitumor, and immunomodulatory activities in patients with neoplastic or viral disease. The antitumor effect of HFIF produced at RPMI as assessed by intralesional injection of various metastatic nodules resulted in an overall 71% local response. Phase I studies in 13 patients demonstrated that HFIF can be administered safely by the subcutaneous, intramuscular, and intravenous routes in doses up to 25 million units per day without any serious untoward effects. Intrathecal administration of HFIF into patients with CNS leukemia was also well tolerated. Pharmacokinetic studies indicated significant levels of HFIF in serum and cerebrospinal fluid after intravenous and intrathecal administration, respectively. Coincidental with the HFIF systemic administration during the Phase I trials, favorable responses in several laboratory, immune, and clinical parameters were observed. These results provide the rationale for conducting phase II and phase III clinical trials with HFIF produced at RPMI.

Inhibition of lymphoma hybrids by human interferon

A set of stable mouse-human hybrids was constructed from the neoplastic lymphocytes from a patient with nodular lymphoma and from another with chronic lymphocytic leukaemia. Both patients had shown a clinical response to human leucocyte interferon. The same interferon preparation inhibited the growth rate of 14 out of 17 established hybrid cell lines. This system provides evidence of a direct growth inhibitory effect of interferon on neoplastic B lymphocytes. Such a system could be used to predict the sensitivity of a patient's tumour before therapy.