Interferon antibodies may negate the antiviral effects of recombinant alpha-interferon treatment in patients with chronic hepatitis B virus infection

Neutralizing antibodies to interferon alfa arising during peginterferon therapy of chronic hepatitis B in children and adults: Results from the HBRN Trials

BACKGROUND AIMS

Pegylated interferon-α (PegIFNα) is of limited utility during immunotolerant or immune active phases of chronic hepatitis B infection but is being explored as part of new cure regimens. Low/absent levels of IFNα found in some patients receiving treatment are associated with limited/no virological responses. The study aimed to determine if sera from participants inhibit IFNα activity and/or contain therapy-induced anti-IFNα antibodies.

APPROACH RESULTS

Pre-treatment, on-treatment, and post-treatment sera from 61 immunotolerant trial participants on PegIFNα/entecavir therapy and 88 immune active trial participants on PegIFNα/tenofovir therapy were screened for anti-IFNα antibodies by indirect ELISA. The neutralization capacity of antibodies was measured by preincubation of sera±recombinant human IFNα added to Huh7 cells with the measurement of interferon-stimulated gene (ISG)-induction by qPCR. Correlations between serum-induced ISG inhibition, presence, and titer of anti-IFNα antibodies and virological responses were evaluated. Preincubation of on-treatment serum from 26 immunotolerant (43%) and 13 immune active (15%) participants with recombinant-human IFNα markedly blunted ISG-induction in Huh7 cells. The degree of ISG inhibition correlated with IFNα antibody titer ( p < 0.0001; r = 0.87). On-treatment development of anti-IFNα neutralizing antibodies (nAbs) was associated with reduced quantitative HBsAg and qHBeAg declines ( p < 0.05) and inhibited IFNα bioactivity to 240 weeks after PegIFNα cessation. Children developed anti-IFNα nAbs more frequently than adults ( p = 0.004) but nAbs in children had less impact on virological responses.

CONCLUSIONS

The development of anti-IFNα nAbs during PegIFNα treatment diminishes responses to antiviral therapy. Understanding how and why anti-IFNα antibodies develop may allow for the optimization of IFN-based therapy, which is critical given its renewed use in HBV-cure strategies.

Suppression of Interferon-α Treatment Response by Host Negative Factors in Hepatitis B Virus Infection

Chronic hepatitis B virus (CHB) infection remains a major global public health issue for which there is still lacking effective curative treatment. Interferon-α (IFN-α) and its pegylated form have been approved as an anti-HBV drug with the advantage of antiviral activity and host immunity against HBV infection enhancement, however, IFN-α treatment failure in CHB patients is a challenging obstacle with 70% of CHB patients respond poorly to exogenous IFN-α treatment. The IFN-α treatment response is negatively regulated by both viral and host factors, and the role of viral factors has been extensively illustrated, while much less attention has been paid to host negative factors. Here, we summarized evidence of host negative regulators and parameters involved in IFN-α therapy failure, review the mechanisms responsible for these effects, and discuss the possible improvement of IFN-based therapy and the rationale of combining the inhibitors of negative regulators in achieving an HBV cure.

Interferon and Hepatitis B: Current and Future Perspectives

Chronic hepatitis B virus (HBV) infection remains a major health burden worldwide for which there is still no effective curative treatment. Interferon (IFN) consists of a group of cytokines with antiviral activity and immunoregulatory and antitumor effects, that play crucial roles in both innate and adaptive immune responses. IFN-α and its pegylated form have been used for over thirty years to treat chronic hepatitis B (CHB) with advantages of finite treatment duration and sustained virologic response, however, the efficacy is limited and side effects are common. Here, we summarize the status and unique advantages of IFN therapy against CHB, review the mechanisms of IFN-α action and factors affecting IFN response, and discuss the possible improvement of IFN-based therapy and the rationale of combinations with other antiviral agents in seeking an HBV cure.

Clinical significance of glatiramer acetate antibodies

Glatiramer acetate is a mixture of synthetic peptides that are cross-reactive with MBP. The antigen-based therapy induces a shift to an anti-inflammatory Th2 bias and is used in the treatment of relapsing-remitting multiple sclerosis. Like other peptide antigens, GA induces an antibody response in all patients. In contrast to biologically active agents, such as the recombinant interferon beta drugs, GA is a peptide antigen that lacks intrinsic biological activity. In vitro and in vivo data have shown that GA-reactive antibodies are not neutralizing. Antibodies do not alter the principal immunological effects of GA, including binding to MHC Class II molecules, activation and proliferation of GA-reactive T cells, and the release of anti-inflammatory Th2 cytokines. Higher antibody titres do not appear to be associated with a deterioration in clinical endpoints, such as relapse rate, EDSS progression or the occurrence of side effects in MS patients treated with GA. The presence of GA-reactive antibodies may promote remyelination and enhance the immunological and clinical effects of GA, indicating that they may be part of GA's mechanism of action. Multiple Sclerosis 2007; 13: S28—S35. http://msj.sagepub.com

A CpG oligodeoxynucleotide inducing anti-coxsackie B3 virus activity in human peripheral blood mononuclear cells

Coxsackie B3 virus (CVB3) is the most significant pathogen causing myocarditis in humans, and antiviral therapy would be most effective in the early stages of the disease. Here we provide evidence that BW001, a C-type CpG oligodeoxynucleotide, induces anti-CVB3 activity in human peripheral blood mononuclear cells (PBMCs). In parallel, we have demonstrated that BW001 induces human PBMCs to express mRNAs of multiple types of interferon (IFN), including IFN-alpha, IFN-beta, IFN-omega and IFN-gamma, and to express mRNAs of at least 11 subtypes of IFN-alpha. The induced IFNs may contribute to the anti-CVB3 activity. The results suggest that BW001 could be developed into a medication with the potential to treat CVB3 infectious diseases by inducing natural mixed IFNs.

Significance of neutralizing antibodies to interferon beta during treatment of multiple sclerosis: expert opinions based on the Proceedings of an International Consensus Conference

On August 30, 2002, an international panel of neurologists who specialize in the treatment of multiple sclerosis (MS) was convened in Paris (France) to discuss the issue of neutralizing antibodies (NAb) to interferon beta (IFN-beta) therapy in patients with MS. The goals of this meeting were to: (i) review the most recent clinical information on NAb, (ii) come to a consensus on the clinical relevance of NAb in the management of patients with MS receiving IFN-beta therapy, and (iii) establish a framework for the development of patient management guidelines based on scientific consensus. The meeting was chaired by Hans-Peter Hartung (Heinrich-Heine University, Düsseldorf, Germany) and Huub Schellekens (Utrecht University, Utrecht, the Netherlands). This article summarizes the opinions of the expert panel on a number of key issues raised at the meeting.

Immunogenicity of therapeutic proteins: clinical implications and future prospects

BACKGROUND

Therapeutic proteins have revolutionized the treatment of many diseases. In the near future, many more therapeutic proteins are likely to become available for an increasingly wide range of indications.

OBJECTIVES

This article reviews the incidence, causes, and consequences of formation of antibodies to therapeutic proteins and suggests ways to address issues surrounding immunogenicity.

METHODS

Searches of MEDLINE and EMBASE databases were performed, covering the period 1990 to May 2002. Search terms included immunogenicity, antibodies, and the names of specific therapeutic proteins and classes of therapeutic proteins. Bibliographies of retrieved articles were not searched.

RESULTS

All exogenous proteins, including therapeutic ones, have the potential to cause antibody formation. The reported incidence of antibody formation with therapeutic proteins varies widely between proteins and between studies (depending on the assay techniques used). The clinical consequences of antibody formation vary with the type of antibody present; for example, neutralizing antibodies are more likely to cause loss of efficacy than nonneutralizing antibodies. The immunogenicity of therapeutic proteins can be influenced by many factors, including the genetic background of the patient, the type of disease, the type of protein (human or nonhuman), the presence of conjugates or fragments, the route of administration, dose frequency, and duration of treatment. Manufacturing, handling, and storage can introduce contaminants, or alter the 3-dimensional structure of the protein via oxidation or aggregate formation. Various means have been suggested by which therapeutic proteins might be modified to reduce their immunogenicity, including PEGylation, site-specific mutagenesis, exon shuffling, and humanization of monoclonal antibodies. In the future, it may even be possible to predict the immunogenicity of new therapeutic proteins more accurately, using specifically designed animal models, including nonhuman primates and transgenic mice.

CONCLUSIONS

Scientists and clinicians are becoming increasingly aware of the importance of assessing the immunogenicity of new molecules as they are introduced, and of existing molecules whenever they are modified or their manufacturing process is changed. Immune responses to therapeutic proteins are usually only of clinical significance if they are associated with the development of treatment resistance. Although various means to reduce the immunogenicity of therapeutic proteins have been suggested, monitoring for antibodies during clinical trials and postmarketing surveillance remains an important issue for all therapeutic proteins.

Neutralizing and binding antibodies to IFN-beta: relative frequency in relapsing-remitting multiple sclerosis patients treated with different IFN-beta preparations

The frequencies of anti-interferon-beta (IFN-beta) antibody development reported to date in patients treated with different IFN-beta preparations are not readily comparable mainly because of differences in underlying diseases and assay methods. Thus, the frequency of neutralizing antibody (NAb) and binding antibody (BAb) development was analyzed in a sample of sera derived from a homogeneous group of relapsing-remitting multiple sclerosis (RRMS) patients treated with different IFN-beta preparations. The frequency of developing NAb and BAb to IFN-beta varied according to the IFN-beta given. Specifically, the NAb seroconversion frequency was significantly higher in patients treated with Betaferon, Schering AG, Berlin, Germany (31.3%) than in patients treated with both preparations of recombinant IFN-beta 1a (Rebif, Serono, Geneva, Switzerland [7.4%] or Avonex, Biogen, Cambridge, MA [6.3%]). Analysis of BAb seroconversion frequency in the same patients revealed that different IFN-beta preparations may also have different capability to induce BAb development and that BAb are produced during IFN-beta therapy at a significantly higher rate than NAb. Our main conclusion is that different human IFN-beta preparations may possess different immunogenicities, leading to varying frequency of development of antibody to IFN-beta in RRMS.

Human immune response to recombinant human proteins

Delivery of pharmacological doses of proteins to people has raised concerns of inducing immune responses, especially when the protein is provided in multiple doses over an extended period of time. Immune responses could impact the therapeutic exposure and efficacy of the protein itself. In addition, there have been fears of anaphylaxis or autoimmunity. This review summarizes the available literature regarding the measurement and evaluation of immune responses observed during clinical assessment of recombinant human proteins. Immune responses have ranged from none at all to inactivation and/or accelerated clearance. Presence of antibodies does not necessarily impact therapeutic viability. While responses are related to frequency and route of delivery, there is no clear relationship that enables one to predict the clinical experience.

Detection and characterization of antibodies to PEG-IFN-alpha2b using surface plasmon resonance

Some patients treated with type I interferon (IFN) preparations develop neutralizing antibodies that may abrogate any clinical benefit. We have a new complex of polyethylene glycol12000 and IFN-alpha2b (PEG-IFN-alpha2b) in clinical trials and need to be able to detect any antibodies formed specifically against the complex. We have, therefore, devised a method based on measurement of surface plasmon resonance (SPR) in the BIACORE 2000 apparatus. PEG-IFN-alpha2b is anchored to one flow cell on the sensor chip, IFN-alpha2b to another, and PEG to a third. A 20 microl serum sample flows in turn through the three cells, which are optically scanned. Any antibodies in the serum bind to the corresponding immobilized antigen, and a change in the optical signal is generated. With appropriate specific reagents, their immunoglobulin isotype can be similarly established. The automated assay can quickly test numerous sera. Very little serum is needed, and the assay is reliable and precise and can detect low-alphaffinity antibodies.

Antigenic characterization of recombinant, lymphoblastoid, and leukocyte IFN-alpha by monoclonal antibodies

To gain more insight into similarities of different interferon-alpha (IFN-alpha) species, we evaluated neutralization and immunoactivity of a variety of IFN preparations with various monoclonal antibodies (IFN-alpha mAb). Nine IFN-alpha mAb obtained through immunization with recombinant IFN-alpha (rmAb), lymphoblastoid IFN-alpha (LY mAb), and leukocyte IFN-alpha (LE mAb) were tested. The IFN-alpha mAb were evaluated for their ability to neutralize the antiviral activity of 11 recombinant IFN-alpha subtypes, two recombinant IFN-alpha hybrids, and lymphoblastoid and leukocyte IFN-alpha preparations. The same IFN-alpha mAb were also used in immunoblotting, and some of them were used in immunoaffinity chromatography. The results of the neutralization assay reveal that the IFN-alpha mAb significantly differ in their ability to neutralize the individual IFN-alpha species. Interestingly, none of the IFN-alpha mAb was able to neutralize all the IFN-alpha species. In particular, rmAb were unable to neutralize LE-IFN-alpha or LY-IFN-alpha, whereas LE mAb and LY mAb efficiently neutralized rIFN-alpha2. In some cases, the epitopes to which IFN-alpha mAb are directed were identified through the use of synthetic fragments of IFN-alpha2 or by evaluating the selectivity in binding to IFN-alpha subtypes.

Development of neutralizing antibodies in patients with relapsing-remitting multiple sclerosis treated with IFN-beta1a

Sixty-eight patients with relapsing-remitting multiple sclerosis (RRMS) were treated with 3 million or 9 million i.u. of recombinant interferon-beta1a (recIFN-beta1a) s.c. three times a week for 2 years. Their sera were tested for antibodies neutralizing the IFN (NAb) in a bioassay. Sera with titers > or = 1:20 were considered positive. We detected NAb in 3.2%, 13.8%, and 15.9% of the patients in sera obtained at 3, 6, and 24 months, respectively. The incidence was not related to the IFN dose. Interestingly, during the 6 month baseline period before the start of the study, relapse rates, baseline disability, and the volume of lesions on T2-weighted images were significantly higher in patients who developed NAb during treatment. Because of interpatient variability, no definitive relationship was observed between NAb formation and loss of clinical or magnetic resonance imaging (MRI) response.

The biology of interferon-alpha and the clinical significance of anti-interferon antibodies

The therapeutic indications for Interferons (IFNs) have dramatically increased in number in recent years to include many different diseases of viral, malignant, angiogenic, allergic, inflammatory and fibrotic origin. In particular, the current pandemic of hepatitis C virus infection has further stimulated the requirement for a comprehensive understanding of both the mechanism of action of IFN and the reasons for therapeutic failure. The role of anti-IFN antibodies as a cause of treatment failure has been a particularly controversial area. In this review we will outline the biology and proposed mechanisms of action of IFN-alpha (IFN-alpha) and discuss the incidence, methods of detection and clinical significance of anti-IFN antibodies.

Role of anti-interferon antibodies in breakthrough occurrence during alpha 2a and 2b therapy in patients with chronic hepatitis C

BACKGROUND/AIMS

Alpha interferon induces aminotransferase normalization in about 50% of patients with chronic viral hepatitis C. However, some patients who initially respond experience a relapse during the treatment period (breakthrough phenomenon). The aim of this study was to evaluate the prevalence of breakthrough and its relationship with the emergence of neutralizing anti-interferon antibodies.

METHODS

We studied 172 patients with histologically proven chronic hepatitis C, treated with interferon alpha 2a or 2b 3 mega units three times a week for 6 months. For each patient, HCV RNA level (polymerase chain reaction and bDNA) and anti-interferon antibodies dosage were determined during therapy.

RESULTS

Among 84 patients with initial response, 13 (15.5%) experienced breakthrough. The kinetics of alanine aminotransferase and HCV RNA levels were strongly correlated, suggesting that breakthrough is not due to a random alanine aminotransferase fluctuation during treatment, but to the reappearance of viral replication. Neutralizing anti-interferon antibodies emergence was observed in 38.5% in patients with breakthrough, as compared to 9.0% and 2.8% of non-responder and complete-responder patients, respectively (p<0.0005). By multivariate analysis, the only factor predictive of breakthrough was the emergence of neutralizing anti-interferon antibodies 3 months after the onset of therapy.

CONCLUSION

Our results suggest that the emergence of neutralizing anti-interferon antibodies during treatment may explain breakthrough in about one third of cases. Other causes may also be responsible for this phenomenon and they remain to be determined.

Differential neutralizing activity of human antibodies in interferon antiviral and natural killer cell bioassays

The ability of interferon-alpha (IFN-alpha) to augment the cytotoxicity of human natural killer (NK) cells was used to probe the neutralization capacity of human antibodies to IFN-alpha. Sera from patients treated with IFN-alpha were tested for antibodies that could bind to IFN-alpha, neutralize IFN-alpha antiviral activity, or neutralize IFN-alpha-mediated augmentation of NK cytolytic activity. The NK-augmenting activity of IFN-alpha was measured in a chromium-release cytotoxicity assay using K562 targets and human peripheral blood mononuclear cells in the presence of a constant amount of antibody from patients treated with IFN-alpha. Neutralization of IFN-alpha-mediated antiviral activity did not correlate with neutralization of NK augmentation. However, all sera that neutralized a biologic activity of IFN-alpha also bound IFN-alpha. Conversely, sera that did not bind to IFN-alpha also did not neutralize either biologic activity. The data suggest that some immunogenic epitopes of IFN-alpha reside in distinct domains that mediate different biologic activities of IFN-alpha. The identification of neutralizing antibodies for the NK immunomodulating function of IFN-alpha but not antiviral function suggests that assessment of antiviral neutralization alone may be an incomplete evaluation of the potential significance of binding antibodies that occur subsequent to the administration of therapeutic IFNs.

Antibodies to interferon-alpha in treated cancer patients: incidence and significance

Antibodies to interferon-alpha (IFN-alpha) are found in some patients being treated with this cytokine. In studies in which two recombinant IFN-alpha preparations were directly compared in cancer patients, those given IFN-alpha2a were found to have neutralizing antibodies in their serum significantly more often than those given IFN-alpha2b (p <0.001). Patients who develop neutralizing antibodies are more likely to have a clinical relapse and to become resistant to further treatment with at least the IFN preparation initially used for their treatment. In 10 studies in cancer patients, such an outcome was found in 63% of those who developed antibodies but in only 13% of those who did not. These data are tabulated.

Interferon antibodies in patients with infectious diseases. Anti-interferon antibodies

Interferons (IFNs) are generally recognized as the most important therapeutic agent in some infectious diseases such as chronic hepatitis B and C. Since the early clinical trials it was documented that the therapeutic use of IFNs could be complicated by the development of antibodies able to neutralize or to bind to the IFN molecule. After several years of research it is now widely accepted that the presence of circulating anti-IFN antibodies may affect the response to IFN. Here we summarize what is currently know on the clinical significance of antibodies to IFN in IFN-treated viral diseases patients.

Structure-activity of type I interferons

Type I IFNs constitute a family of proteins exhibiting high homology in primary, secondary, and tertiary structures. They interact with the same receptor and transmit signals to cellular nucleus through a similar mechanism, eliciting roughly homogeneous biological activity. Nevertheless, the members of that family, IFN alpha species, IFN beta and IFN omega, due to local differences in the structure sometime show distinct properties. From the reported data it results that even minute changes or differences in the primary sequences could be responsible for a significant variety of biological actions, thus inducing to the hypothesis that Type I IFNs, rather than to be the result of a redundant replication during the evolution play definite roles in the defense of living organisms to foreign agents.

Interferon-alpha for viral hepatitis

IFN-alpha has emerged as a promising treatment of chronic viral hepatitis. Although therapeutic response to IFN is far from universal, efficacy has been demonstrated; and studies combining IFN-alpha with other agents, as well as trials with new preparations of IFN-alpha, are under way. Children do not represent a large part of the identified population with chronic viral hepatitis. Yet children, by simple virtue of age, are more recently infected. In addition, longer life expectancies can be expected to be associated with greater morbidity from chronic viral hepatitis. Children seem to tolerate therapy with IFN-alpha well. Treatment of children with chronic viral hepatitis should be strongly considered, with protocols designed to ascertain specific pediatric safety and efficacy.

Natural leukocyte interferon-alpha therapy in patients with chronic granulocytic leukemia who have antibody-mediated resistance to treatment with recombinant interferon-alpha

Two patients with chronic-phase chronic granulocytic leukemia initially responded to recombinant interferon alpha-2a (rIFN-alpha-2a) but relapsed as a result of development of hightiter neutralizing antibodies to rIFN-alpha-2a. Both patients were subsequently treated with natural leukocyte IFN-alpha (IFN-alpha-n3), and one of the two patients achieved a durable second hematologic and cytogenetic remission. IFN-alpha-n3 may be considered for patients in whom antibody-mediated resistance to rIFN-alpha-2a develops.

A rational approach to the management of hepatitis C infection

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Interferon-alpha-2a. A review of its pharmacological properties and therapeutic use in the management of viral hepatitis

Interferon-alpha-2a is a recombinant interferon with antiviral, antitumour and immunomodulatory properties. Clinical studies have demonstrated that the drug offers therapeutic benefit in patients with some forms of chronic viral hepatitis. Remission, as measured by clearance of viral DNA and hepatitis B 'e' antigen (HBeAg), and normalisation of serum alanine aminotransferase levels, is observed in approximately 30 to 45% of patients with chronic hepatitis B receiving interferon-alpha-2a (2.5 to 18MU administered 3 times/week); about 5 to 15% of untreated controls remit spontaneously every year. Complete recovery [with loss of hepatitis B surface antigen (HBsAg)] is usually noted in < 20% of treated individuals. Similar response rates have been reported in the relatively small number of children evaluated to date. Although numerous studies have shown that interferon-alpha-2a (at various dosages) induces biochemical amelioration of chronic hepatitis C in approximately 50 to 75% of patients, relapse is common. Thus, long term remission may only be observed in about 15 to 30% of treated patients. On the other hand, this disorder remits spontaneously in only a few patients. The role of interferon-alpha-2a in the treatment of chronic hepatitis D remains unclear. Although preliminary data suggest it may be beneficial, cessation of therapy is generally followed by relapse. As with other types of interferons, most patients receiving interferon-alpha-2a experience an 'influenza-like' syndrome, which tends to diminish with continuing therapy. Other effects such as fatigue, lethargy, anorexia and weight loss are usually dose-limiting. Serum neutralising antibodies develop in approximately 10 to 20% of treated patients. Thus, although response rates are less than optimal, interferon-alpha-2a is a drug of first choice amongst the limited therapeutic options available for the management of well-compensated chronic viral hepatitis B or C.

Treatment of chronic hepatitis B

Chronic infection with the hepatitis B virus (HBV) is a major cause of worldwide morbidity and mortality. A large number of therapeutic approaches has been tried, including interferon (IFN), nucleoside analogues and immunomodulators. To date controlled clinical trials have shown that only IFN is of long-term value but many patients fail to respond to treatment. New approaches to treating patients with IFN-resistant hepatitis B are currently undergoing clinical and experimental evaluation, and it seems likely that new therapeutic agents will be available in the near future.

Cytokines in the treatment of virus infections

The interferon (IFN) system consists of both the formation of the various IFN proteins, and the diverse cellular responses which these induce: these result from the intracellular changes which follow their binding to a specific cell surface receptor. There is only a single human gamma, omega and beta IFN; in contrast, there are 13 closely related chemical species ("subtypes") of human alpha IFN, which are nevertheless chemically and biologically distinct. IFN preparations made from mass cultured human cells or by using recombinant DNA techniques are now readily available for clinical use. IFN have a major role in the defence of the body against virus infections. In acute virus infections, preformed exogenous IFN cannot be given soon enough to be of value. However, IFN-alpha and IFN-beta have proved of considerable value in some chronic virus infections, particularly chronic virus hepatitis and chronic papillomavirus infections. The doses routinely used are associated with both acute and chronic toxic side effects. Also, some patients form specific neutralising antibodies against the particular IFN preparation injected, which may abrogate all the benefits of the treatment. Nevertheless, IFN are now established as agents for use in routine medical practice.

Effects of type I-interferons on human thyroid epithelial cells derived from normal and tumour tissue

Long term interferon (IFN) therapy is frequently associated with side effects which affect the thyroid gland such as hypothyroidism and thyroiditis. We have therefore tested the ability of type I-IFNs to exert direct effects on primary cultures of human thyroid epithelial cells: (i) Type I-IFNs (IFN-alpha 2b and IFN-omega) inhibit cell proliferation as determined by [3H]thymidine incorporation with a half-maximal effect at approximately 1 ng/ml (50 pM). Inhibition of cell growth is observed in cells derived from normal thyroid as well as neoplastic tissue (autonomous and non-secreting adenoma; follicular, papillary and anaplastic carcinoma). (ii) Over a similar concentration range, type I-IFNs suppressed thyroglobulin release by thyroid cells. (iii) IFN-alpha 2b stimulated surface expression of major histocompatibility class (MHC) I but not MHC II molecules, while IFN-gamma enhanced the expression of both MHC I and MHC II molecules. This effect of IFN-gamma, but not that of IFN-alpha 2b was antagonized by suramin. (iv) Incubation of thyroid cells with IFN-alpha 2b also resulted in increased cell surface levels of the intercellular adhesion molecule 1 (ICAM-1). These findings demonstrate that type I-IFNs directly affect thyroid function and explain related side effects of these cytokines. In addition, our results provide a rational basis for the possible use of type I-IFNs in the treatment of patients with advanced thyroid cancer for whom no therapeutic alternative exists.

The role of interferon in the treatment of viral hepatitis

Chronic viral hepatitis, frequently an asymptomatic disease, can persist for decades. Despite the lack of symptoms, prolonged infection can lead to the complications of cirrhosis, liver failure and hepatocellular carcinoma. The goal of therapy is to reduce the risk of developing these complications and to eradicate the infectious pool. Patients with ongoing viral replication appear to be at greatest risk for developing complications. These patients have been targeted for treatment. Numerous randomized studies of interferon treatment of chronic hepatitis B and C have been published in the last 8 years. The experience from these studies and more recent developments will be reviewed.

Biological and clinical significance of neutralizing and binding antibodies to interferon-alpha (IFN-alpha) during therapy for chronic hepatitis C

It is known that IFN therapy can induce the development of anti-IFN antibodies. In order to evaluate the biological and clinical significance of both neutralizing (NA) and non-neutralizing (binding) antibodies, 123 patients with chronic hepatitis C treated with recombinant IFN-alpha were examined. Among them, 15 were positive for NA and 24 for binding antibodies. The kinetics of NA appearance show that, in general, they develop early during the first 3 months of treatment. Moreover, NA seem to be clinically relevant, since they may be responsible for non-responsiveness to treatment in 53% of patients who develop them. The evaluation of the clinical significance of binding antibodies is more difficult. They appear significantly earlier in non-responders than in responders, but no differences were observed in the overall percentage of seroconversion between responders and non-responders. Thus, it is not possible at the moment to establish their possible role in inducing non-responsiveness.

Development of neutralizing and binding antibodies to interferon (IFN) in patients undergoing IFN therapy

Since the 1970's, people started to use interferon as a therapeutic agent against infectious and neoplastic diseases. Since the beginning of its therapeutical use, it was demonstrated that some patients produce, when treated with interferon, antibodies able to neutralize its biological activity. This paper will review and discuss what it is currently known about the technical, biological, and clinical aspects of these antibodies.

Beneficial effect of prednisolone withdrawal followed by human lymphoblastoid interferon on the treatment of chronic type B hepatitis in Asians: a randomized controlled trial

To evaluate the effect of interferon and the benefit of prednisolone pretreatment in Oriental patients with chronic active hepatitis B, 120 male Chinese patients were randomly allocated to receive: 1) group A: a 4-week course of prednisolone followed by 2 weeks of no treatment and then a 12-week course of human lymphoblastoid interferon, 4 to 6 MU/m2 intramuscularly; 2) group B: as group A, but with placebo given instead of prednisolone; 3) group C: an 18-week course of placebo. Clearance of serum hepatitis B virus-DNA and HBeAg (complete response) was achieved in 21% of group A, 5% of group B and none of group C at the end of therapy (A vs B: p = 0.054; A vs C: p < 0.01). When assessed 12 months after the end of therapy, the complete response rate was 46% in group A, 24% in group B and 25% in group C (p < 0.05). Those with baseline alanine transaminase < or = 200 U/l showed a better response to interferon following prednisolone withdrawal (48%) than with interferon therapy alone (20%, p = 0.056) and no treatment (9%, p < 0.01). Those with a baseline serum hepatitis B virus-DNA < or = 1000 pg/ml also showed a higher complete response rate when pretreated with prednisolone (59%) than when treated with interferon alone (29%, p = 0.084) or untreated (22%, p < 0.03). The strongest independent predictor of a response to treatment was prednisolone withdrawal (p < 0.05). None of the responders lost hepatitis B surface antigen.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical toxicity of the interferons

Since their initial description in 1957, the interferons (IFNs) have been increasingly used to treat a wide array of diseases. Acute adverse effects, i.e. 'flu-like' syndromes, hypo- or hypertension, tachycardia, headache, myalgias and gastrointestinal disorders, occur within the first hour or day after starting treatment. They are seldom treatment-limiting and are easily manageable. Sub-acute and chronic effects develop after several days, usually within 2 and 4 weeks of therapy. The most typical is neurological toxicity, including fatigue/asthenia, and behavioural and cognitive changes. Such symptoms may seriously impair quality of life and result in treatment discontinuation. Seizures have seldom been described. Other infrequent central nervous system adverse effects include vertigo, cramp and oculomotor nerve paralysis. Distal paraesthesias and peripheral neuropathy have been reported. IFN-associated autoimmunity is quite rare but a matter of concern. Biological or clinical manifestations usually require several months to become apparent. Autoantibodies have been shown to develop in most patients but have been inconsistently associated with clinical symptoms of systemic lupus erythematosus, rheumatoid-like arthritis and thyroiditis. Both hypo- and hyperthyroidism have been described but are usually reversible. Other infrequent autoimmune reactions include diabetes, pemphigus and worsening of multiple sclerosis. Although several patients present with a pre-existing autoimmune disorder, no predisposing factor has been clearly established. While hypotension and tachycardia are the most frequent acute cardiovascular complications, a few additional cases of cardiac arrhythmias and myocardial ischaemia have been reported after a short course or several weeks of treatment. These latter complications do not appear to be dose-dependent or age-related. Isolated cases of congestive heart failure have also been described. Mild proteinuria has been observed in 15 to 25% of patients, but acute renal toxicity is uncommon. A transient rise in serum aminotransferase levels is frequently noted during the first stage of therapy, especially in patients receiving the highest dosages. Direct hepatotoxicity is extremely rare. Autoimmune hepatitis, which is ill-diagnosed as chronic viral hepatitis, and de novo induction of autoimmune hepatitis, account for the majority of liver diseases. Haematotoxicity is relatively common but mild to moderate, and develops gradually during the first weeks of treatment. Neutropenia is the most common haematological toxicity, but is usually not dose-limiting and resolves rapidly upon drug discontinuation. Myelosuppression, autoimmune and immune allergic haemolytic anaemias and thrombocytopenias have seldom been described. Cutaneous adverse effects comprised nonspecific erythema and hair loss and, less frequently, vasculitis, local ulcerations at the site of injection and exacerbation of psoriasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Interferon treatment of chronic hepatitis C

The natural history of chronic hepatitis C is just beginning to be clarified, with its more common course being an insidiously progressive liver disease that often remains clinically inconsequential for many years or even decades. Although chronic hepatitis C progresses histologically, the impact on the clinical well-being of the patient is less evident. Interferon is an effective therapy for this disease because of its antiviral effect on the cytopathic hepatitis C virus, lowering serum alanine aminotransferase (ALT) levels, rather than because of any immune modulatory mechanism. Unfortunately, interferon therapy does not permanently eradicate hepatitis C virus in the majority of patients, and relapse with return of the serum ALT level to the pretreatment range occurs in approximately 70% of responding patients. Other interferon-treated patients continue to be viremic and are not considered to be responders. In addition, not all patients with chronic hepatitis C require treatment. A systematic approach to patient evaluation is necessary to determine the need for treatment, assess treatment response, identify side effects of therapy, and assist in other clinical decisions.

Neutralizing antibodies to recombinant alpha-interferon and response to therapy in chronic hepatitis C virus infection

Forty-seven patients with chronic hepatitis C were treated with recombinant interferon alpha-2a (rIFN alpha 2a) given subcutaneously in a standard dose of 3 MU thrice weekly for 12 months. Stored baseline sera and monthly samples during treatment were assayed for anti-interferon neutralizing antibodies using the antiviral neutralization bioassay against 5 IU of rIFN alpha 2a. During therapy, 15 of 47 patients (31.9%) developed detectable levels of neutralizing antibodies within 2-8 months after starting treatment. After 12 months of therapy, 26 of 32 antibody-negative patients (81.3%) showed normalization or marked reduction of ALT levels compared to 4 of 15 (26.6%) who developed anti-IFN neutralizing antibodies (p = 0.0009). Four patients demonstrated antiviral response during treatment even in the presence of low levels or late occurrence of neutralizing antibodies. Six of the seven patients who had disease reactivation after an initial response developed high titers of neutralizing antibodies. Our results suggest that reactivation of chronic hepatitis C before completion of therapy seems to be an obvious consequence of anti-IFN neutralizing antibody formation.

Randomized controlled trial of recombinant alpha-2a-interferon for chronic hepatitis C. Comparison of alanine aminotransferase normalization versus loss of HCV RNA and anti-HCV IgM

We enrolled 32 patients with chronic hepatitis C into a randomized, controlled trial to evaluate the efficacy of recombinant alpha-2a-interferon treatment. Sixteen patients were randomized to receive 1.5 million units of recombinant alpha-2a-interferon subcutaneously, thrice weekly, for six months while the remaining 16 patients were randomized to a control group that received no treatment. The mean serum alanine aminotransferase (ALT) level during the six-month study period, expressed as a percentage of the prestudy baseline value, was 82% for the control group compared to 56% for the treatment group (P = 0.014). One fourth of the treatment group normalized their serum ALT level compared to only 6% of the controls (P = 0.05). During posttherapy follow-up, 86% of responders clinically relapsed. Loss of anti-HCV IgM and HCV RNA occurred exclusively in interferon-treated responders. Anti-interferon antibodies developed in 32% of all treated patients. Forty percent of nonresponders developed anti-interferon antibodies compared to only 14% of responders (P = NS). We conclude that recombinant alpha-2a-interferon is clinically effective in patients with chronic hepatitis C. However, most responders in this trial of low-dose interferon relapsed upon cessation of treatment.

Interferon in the management of chronic hepatitis B

Many drugs have been used in the treatment of chronic hepatitis B, but with the exception of interferon, none have proved to be effective. Several studies have found that a sustained loss of viral replication occurs in approximately 40% of patients who started with a 16-week course of recombinant interferon alfa-2b given in a dose of 5 million units daily or 10 million units three times weekly. Moreover, disappearance of hepatitis B surface antigen in serum has been observed in 10-15% of treated patients. Based on these results, the Food and Drug Administration approved the use of this form of interferon in chronic hepatitis B in July 1992. This article reviews the importance of chronic hepatitis B as a health problem as well as the mechanisms of action, benefits, and adverse effects associated with interferon. Particular emphasis is given to the safety and efficacy data for recombinant interferon alfa-2b.

An escalating dose regime of recombinant interferon-alpha 2A in the treatment of chronic hepatitis C

Interferon-alpha (IFN-alpha) has proven useful in the treatment of chronic hepatitis C, but a relapse in response is frequently observed. The possible benefit of daily administration of recombinant IFN-alpha 2A at an escalating (from 1.5 to 9 MU) regime depending on the evolution of serum aminotransferase (ALT) levels was evaluated in 31 adult patients with chronic hepatitis C. At the end of the first month with 1.5 MU of rIFN-alpha 2A, 9/31 (29%) had normal ALT values. Then, 22 patients were given 3 MU daily and at the second month 4 patients (18%) normalized ALT values. The 18 non-responders received 6 MU and 4 of them (22%) normalized ALT values (1 patient dropped out). Finally, the remaining 13 non-responders were given 9 MU and in 4 (30%) ALT fell to normal ranges. Three non-responders to 1.5 MU normalized ALT values when the dose of rIFN-alpha 2A was increased (n = 2, 3 MU; n = 1, 9 MU). The overall response achieved was 68%. Within 3 months after cessation of treatment, 12/20 (60%) responder patients had a relapse in ALT levels. Therefore, although daily administration of rIFN-alpha 2A does not improve the results obtained with a thrice-weekly schedule, a proportion of non-responders could benefit from an escalating dose to a high amount (63 MU/week) of rIFN-alpha 2A.

Repeated courses of alpha-interferon for treatment of chronic hepatitis type B

In chronic hepatitis B transition from active replication to viral latency (HBeAg seroconversion) usually leads to remission of the disease. alpha-Interferon (IFN) therapy induces HBeAg seroconversion in about one-third of the patients, thus leaving the majority of patients with persistent disease. Eighteen chronic hepatitis B patients who did not respond (HBeAg seroconversion and clearance of HBV-DNA) to an initial 16-week course of IFN subsequently received IFN again after at least 6 months of no therapy. The repeated therapy consisted of 1.5-5 MU lymphoblastoid IFN daily for 16 weeks. Treatment effects were monitored by quantitative measurement of HBeAg and HBV-DNA. To analyze whether the results were related to patient characteristics known to affect the response to initial treatment, a predicted response rate, based on pre-treatment factors, was determined. After a follow-up of 52 weeks, 2 of the 18 patients (11%) had responded to therapy. Two additional patients became HBV-DNA-negative with sustained HBeAg positivity. All patients remained HBsAg-positive. According to the pre-treatment parameters, a response was predicted for 9 of the 18 patients (50%). This predicted response rate was significantly higher than the actual response rate (p = 0.03). In conclusion, this pilot study with moderate dosages of IFN suggests that the HBeAg seroconversion rate after repeated IFN treatment is low for previous non-responders and probably is not related to important clinical characteristics that influence the response to initial IFN treatment. A large controlled trial with higher doses of IFN is desirable to further evaluate the benefits of retreatment.

Antiviral therapy of chronic hepatitis B: past, present, and future

A wide variety of agents has been used to treat chronic hepatitis B, but none has proved effective with the exception of interferon. Toxicity has been a major problem with some drugs whereas in others a lack of antiviral potency has been demonstrated. Alpha-interferon represents a good compromise because it has both immunomodulatory and antiviral properties; moreover, it is generally well tolerated. Loss of HBeAg and hepatitis B virus DNA may be anticipated in 40-50% of patients who are treated with doses of 5 million units daily or 10 million units thrice weekly for 16 weeks. While drug-related adverse effects occur commonly, the majority of clinically stable patients are able to tolerate this regimen, and withdrawal from drug is necessary in approximately 5% of patients. Unlike the situation with chronic hepatitis C, loss of viral replication tends to be sustained years later. Disappearance of HBsAg only occurs in 10-15% of treated patients within the first year after therapy, but an increasing number of responders demonstrate HBsAg seroconversion upon prolonged follow-up. Hepatitis B virus DNA usually disappears from serum by polymerase chain reaction at the time of HBsAg loss. Low copy numbers of residual viral DNA are still detectable in liver tissue at this time, but this has uncertain significance. Marked improvement in histological features has been observed years after loss of HBsAg. Pre-therapy levels of circulating viral DNA and aminotransferase activity, degree of histologic activity, and HIV status appear to influence the response to therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies to interferon alpha in patients

A massive amount of information on interferons (IFNs) has been gathered since their original description as antiviral agents in 1957. Human IFNs have now been used clinically for over a decade and their therapeutic efficacy has been well established for some human neoplasias and viral diseases. During these studies, it has also been documented that some of the patients treated with IFNs can develop antibodies to IFNs which can affect their therapeutic efficacy. Here, it is summarized what is currently known on the biological and clinical aspects of these antibodies.

A controlled trial of interferon with or without prednisone priming for chronic hepatitis B

In a randomized, controlled trial of recombinant interferon alfa-2b with or without prednisone priming in Chinese adults with chronic hepatitis B virus infection, stratified randomization for pretreatment serum alanine aminotransferase levels was done. Partial or complete antiviral responses were achieved in 17 (21.5%) of 79 treated patients and 3 (8.3%) of 36 controls (P = 0.14). The response to interferon treatment was significantly better in those who had elevated pretreatment transaminase levels and comparable to that reported in white patients [15 (38.5%) of 39 patients compared with 2 (5%) of 40 who had normal pretreatment transaminase levels (P = 0.0005)]. The spontaneous seroconversion rate was also higher among the controls with elevated transaminase levels [3 (18.8%) of 16 compared with 0 of 20 with normal transaminase levels], but this difference was not statistically significant (P = 0.16). Among the interferon-treated patients, prednisone priming appeared to have a marginal benefit over treatment with interferon alone in patients with elevated transaminase levels (43% vs. 33%), but not in those with normal transaminase levels (0% vs. 9.5%). It was confirmed that Chinese patients with normal transaminase levels respond very poorly to interferon alfa therapy. However, the response was significantly better in patients with elevated transaminase levels.

Alpha-interferon therapy for chronic hepatitis B virus infection in children and Oriental patients

In summary, these four studies showed that alpha-IFN therapy alone produced sustained inhibition of HBV replication in a minority of Chinese adults with chronic HBV infection. The response was not improved by instituting treatment at an earlier age. The major reason for the poor response in Chinese patients is probably immune tolerance as a result of early exposure to HBV. The response in Chinese patients with elevated pre-treatment serum ALT levels, who presumably had ongoing endogenous immune lysis of infected hepatocytes, was significantly better than and comparable with that reported in Caucasian patients. Prednisone priming did not provide any additional advantage over therapy with IFN alone in patients with normal pre-treatment serum ALT levels, but appeared to have additional benefit in patients with elevated ALT levels.

The use of interferon-alpha in virus infections

The interferons (IFN) act too slowly to arrest acute viral infections, but interferon-alpha (IFN alpha) preparations have proved useful in some chronic infections and will clearly be used increasingly in these in the future. In the preparations derived from human leucocytes or cultured B lymphoblastoid cells, which are in routine clinical use, mixtures of a number of distinct subtypes of human IFN alpha have been identified. There are also 3 slightly different versions of the same single subtype, IFN alpha-2, made by recombinant DNA procedures in bacteria. IFN alpha preparations are injected intramuscularly or subcutaneously. Dose-related side effects are common but usually tolerable, but prolonged treatment may cause increasing fatigue and depression. Some patients form neutralising antibodies which block the effects of the IFN; these appear to be relatively more common after recombinant IFN alpha-2 than after IFN derived from human cells. Given intranasally, IFN alpha can prevent a subsequent experimental rhinovirus infection, or the spread of natural colds within a family. Repeated administration progressively damages the nasal mucosa, so that long term prophylaxis is not possible. IFN alpha has proved useful in patients with papillomavirus warts of the larynx, ano-genital region (condyloma acuminata) and skin (common warts). Treatment regimens remain to be optimised and are likely to include surgery or other treatments. IFN alpha and zidovudine (azidothymidine) synergistically inhibit the growth of HIV in vitro, and combination are on trial in patients with early AIDS. Very large doses of IFN alpha are effective against Kaposi's sarcoma in some AIDS patients. In chronic hepatitis B, continuing virus replication may lead to cirrhosis or primary liver cancer. Earlier clinical trials with IFN alpha gave inconclusive results, but recent large studies have confirmed that 25 to 40% of patients obtain benefit; this probably results from both the antiviral and the immunomodulatory effects of IFN alpha. In patients with chronic hepatitis C, the biochemical markers usually improve rapidly during IFN alpha administration, but relapse if treatment is stopped after only a few months; to increase the chances of sustained cure, the treatment period is now being prolonged.