New and modified interferon alfas: preclinical and clinical data

Hepatitis B and C

Chronic viral hepatitis is a global health threat and financial burden. Hepatitis B and C viruses (HBV and HCV) are the most common causes of chronic viral hepatitis in the United States. Most cases are asymptomatic before adulthood. Research has resulted in effective therapy for HCV and the promise of effective therapies for HBV. For HCV, therapy is pegylated interferon and ribavirin. Clinical trials with effective direct-acting antiviral agents are underway in pediatrics. For HBV, approved agents are alpha-interferon, lamivudine, adefovir, tenofovir, and entecavir. However, treatment seldom results in functional cure and more effective therapies are urgently needed.

Cytokine immunomodulation for the treatment of infectious diseases: lessons from primary immunodeficiencies

Traditionally, management of infectious diseases focuses on identification of the causative microbe and the use of pathogen-targeted therapy. With increasing antimicrobial resistance, novel approaches are required. One strategy is to modulate those natural host immune responses that critically mediate resistance to specific microbes. Clinically, this host-directed tactic could be used either alone or in combination with antimicrobial therapy. While conceptually attractive, there is potential concern that the pathways governing host resistance to pathogens in animal models may not extrapolate linearly to humans. Targeting these immune processes clinically may precipitate damaging, epiphenomenal responses. The field of Primary Immunodeficiencies focuses on the characterization of humans with inborn errors of immunity. These rare conditions permit the identification of those molecular and cellular processes that are central to human susceptibility to microbes. In efforts to compensate for defective host responses, this field has also provided a wealth of clinical experience in the effective use of cytokines to treat various active infections, while demonstrating their safety. In this review, we provide a historical perspective of the treatment of infectious diseases, evolving from a focus on the microbe, to an understanding of human immunity; we then outline the growing contribution of Primary Immunodeficiencies to the rational use of adjunctive cytokine immunotherapy in the management of infections.

Efficient co-expression of bicistronic proteins in mesenchymal stem cells by development and optimization of a multifunctional plasmid

INTRODUCTION

Local synthesis of interferon within B16 tumors mediates anti-tumor effects. Based on reports that stem cells are recruited to tumors, and because systemic administration of interferon causes dose-limiting undesirable side effects, we wanted to improve the anti-tumor effects of interferon while simultaneously minimizing its systemic side effects by employing mesenchymal stem cells (MSCs) as tumor-localized ectopic producers of interferon. Many vectors exist to fulfill this purpose, but their transfection efficiency and resulting expression levels vary considerably.

METHODS

To follow both the recruitment to tumors and the synthesis of interferon by MSCs, we designed a bicistronic vector system that permits fluorescent visualization of vector-transfected and interferon-producing MSCs. We used Mu-IFNαA cDNA as the first cistron and the cherry fluorescent protein cDNA as the second cistron, whose translation requires the internal ribosome entry sequence (IRES) from the encephalomyocarditis virus 5' untranslated region. Observing inconsistent expression of these cistrons in various vectors and cell lines, especially compared with a control plasmid pmaxGFP, we optimized the expression of this bicistronic message by mutating pcDNA3 to facilitate exchange of the promoter and polyadenylation segments controlling both the gene of interest and the eukaryotic antibiotic resistance gene as well as the eukaryotic antibiotic resistance gene itself, and effectively compare the effects of these exchanges, creating plasmid pc3.5.

RESULTS

Murine MSCs stably and ectopically expressing Mu-IFNαA inhibited the establishment of tumors in homogeneic C57/BL6 mice. Mu-IFNαA expressed from the bicistronic message is fully biologically active, but is expressed at only two-thirds of the level observed from a monocistronic message. Cap-dependent translation is threefold more efficient than IRES-driven translation in 293T, B16, and MSC cell lines. Both efficient expression and good transfection efficiency require strong expression of the gene of interest and a chimeric intron. High doses of Mu-IFNαA within tumors inhibited tumor establishment but may not inhibit tumor growth.

CONCLUSIONS

Our modified vector and its derived plasmids will find use in stem cell therapeutics, gene expression, mRNA regulation, and transcription regulation. Local release of Mu-IFNαA within tumors may differently affect tumor establishment and tumor growth.

Phase I Dose Escalation Study of Sodium Stibogluconate (SSG), a Protein Tyrosine Phosphatase Inhibitor, Combined with Interferon Alpha for Patients with Solid Tumors

Purpose: Sodium stibogluconate (SSG), a small molecule inhibitor of protein tyrosine phosphatases, combined with IFN-alpha-2b (IFN-α) inhibited solid tumor cell line growth in vitro. We conducted a phase I clinical trial with SSG plus IFN-α in advanced cancer patients to assess tolerance, maximum tolerated dose (MTD) and immune system effects.

Experimental Design: SSG was administered intravenously alone for five days of week 1, cycle 1 (21 days per cycle) and together with IFN-α 2b s (3 million units sc TIW) in week 2, and after a rest during week 3, on a 2-week on/1-week off cycle. SSG dose levels were 400, 600, 900, 1125, and 1350 mg/m².

Results: Twenty-four patients were studied. Common toxicities included asymptomatic elevated serum lipase, thrombocytopenia, fatigue, fever, chills and anemia. The dose-limiting toxicities (DLT) were hypokalemia, thrombocytopenia, fatigue, pancreatitis and skin rash. The MTD was 900 mg/m² SSG and IFN-α, 3 million units TIW. At this dose, patients had a significantly lower number of regulatory T cells (T_R Cells) (p = 0.012), myeloid dendritic cells (mDC) (p = 0.028); higher percentage of natural killer (NK) cells that synthesized perforin (p = 0.046) and of plasmacytoid dendritic cells (pDC) that secreted IFN-α (p = 0.018) in response to activation through toll-like receptor (TLR) 7 and TLR 8 by CL097, the highly water-soluble derivative of the imidazoquinoline compound R848.

Conclusions: SSG in combination with IFN-α 2b was well tolerated and augmented cellular immune parameters.

Managing pediatric hepatitis C: current and emerging treatment options

Since 1992, the maternal–fetal route of transmission has become the dominant route for acquisition of hepatitis C (HCV) infection by children. With increasing knowledge of antiviral treatment for HCV infection, the main goal of therapy is to achieve a sustained virological response (SVR) as defined by undetectable serum HCV RNA by polymerase chain reaction assay six months after cessation of therapy. In young children, interferon therapy is more effective than in adults with chronic HCV infection (CHC). Although children clearly have a milder degree of liver pathology, data have indicated that hepatic inflammation from HCV infection can progress to fibrosis or cirrhosis in children. Hepatocellular carcinoma has been reported in adolescents with CHC. In this article, recent improvements in therapy of children with CHC and in the clinical development of new emerging drugs with potential use in children will be reviewed.

Novel Delivery Systems for Interferons

Interferons, IFNs, are among the most widely studied and clinically used biopharmaceuticals. Despite their invaluable therapeutic roles, the widespread use of IFNs suffers from some inherent limitations, mainly their relatively short circulation lifespan and their unwanted effects on some non-target tissues. Therefore, both these constraints have become the central focus points for the research efforts on the development of a variety of novel delivery systems for these therapeutic agents with the ultimate goal of improving their therapeutic end-points. Generally, the delivery systems currently under investigation for IFNs can be classified as particulate delivery systems, including micro- and nano-particles, liposomes, minipellets, cellular carriers, and non-particulate delivery systems, including PEGylated IFNs, other chemically conjugated IFNs, immunoconjugated IFNs, and genetically conjugated IFNs. All these strategies and techniques have their own possibilities and limitations, which should be taken into account when considering their clinical application. In this article, currently studied delivery systems/techniques for IFN delivery have been reviewed extensively, with the main focus on the pharmacokinetic consequences of each procedure.

Old and emerging therapies in chronic hepatitis C: an update

The main goal of therapy in hepatitis C virus (HCV) infection is to achieve a sustained virological response currently defined as undetectable HCV-RNA in peripheral blood determined with the most sensitive polymerase chain reaction technique 24 weeks after the end of treatment. This goal is practically equivalent with eradication of HCV infection and cure of the underlying HCV-induced liver disease. The current standard in hepatitis C treatment consists in combination regimens of pegylated interferon-alpha (Peg-INF-alpha) with Ribavirin (RBV). Such treatment schemes are quite successful in patients with HCV genotypes 2 and 3 infections achieving HCV eradication rates of 75-90%. However, they are much less effective in patients with genotypes 1 and 4 infections with eradication rates ranging between 45% and 52%. Moreover, they have several, and sometimes severe, adverse effects and contraindications, further limiting their efficacy and applicability in an appreciable number of patients with chronic HCV-induced liver disease. Therefore, the need for improvement of existing therapies and for development of new effective, safe and tolerable drugs is a matter of great clinical relevance and importance. In this article, recent improvements in the current standard of therapy with IFN-alpha and RBV in various subsets of patients with chronic hepatitis C and in the clinical development of new emerging drugs, particularly small molecules, will be reviewed and commented. The article is divided in two main parts: (i) improvements in the standard combination therapies and schemes of approved Peg-INF-alpha with RBV and expectations from new interferons, interferon inducers and alternatives to RBV; (ii) new drugs for HCV in clinical development focusing mostly on specific inhibitors of HCV and less so on other drugs including immune therapies.

Small molecule and novel treatments for chronic hepatitis C virus infection

The development of molecular-based therapies for the treatment of chronic hepatitis C virus (HCV) infection is an area of intense clinical research, driven by the inability of the current standard of care, combination therapy with pegylated interferon alfa (PEG-IFNalpha) and ribavirin (RBV), to achieve a sustained virologic response (SVR) in a large proportion of patients and by the lack of approved alternative therapies for PEG-IFNalpha/RBV nonresponders and relapsers. Agents being developed against specific HCV viral proteins have recently been termed Specifically Targeted Antiviral Therapy for HCV (STAT-C). Preliminary data for several agents show they have high antiviral activity, especially when used in combination with PEG-IFNalpha, and are tolerable, but resistance mutations have been identified. Further study is needed to clarify the safety, tolerability, and efficacy of these compounds. Once established, the potential for shorter treatment strategies could then be evaluated. Other novel therapies in development that may improve both outcomes and tolerability include a prodrug of RBV and an albumin-modified IFNalpha. In conclusion, small molecule and novel therapies for HCV infection are showing promise in clinical trials, and research to develop new agents and optimize treatment regimens is ongoing.

Interferon-based treatment of chronic hepatitis C

The treatment of patients with chronic hepatitis C has rapidly evolved in the past 10 years centered on the use of interferon alpha 2 as an antiviral and immunomodulatory agent against hepatitis C virus. Firstly used as a monotherapy associated with a deceiving long-term efficacy, interferon alpha was then combined with ribavirin, a nucleoside analog with large antiviral properties. Combination of both drugs dramatically improved the efficacy of treatment with 50% of patients reaching a sustained viral response, characterized by the final eradication of the virus from the infected individual. Surprisingly, this synergistic effect remains greatly unexplained. The third step consisted in the use of pegylated interferon in order to adapt its pharmacokinetics and to allow a better efficacy with a more tolerable dosing schedule: once weekly subcutaneous injection instead of thrice weekly. Pegylated interferon combined with ribavirin during 24-48 weeks of treatment is the current standard of care with nearly 60% of sustained virologic response, overall. Development of new forms of interferon alpha are on the way with promising preliminary results.

[New therapies for hepatitis C]

Hepatitis C virus is an important public health threat, not only because of the high prevalence of this infection in western and third world countries, but also because of the high rate of resistance to the available antiviral therapy that consists on the use of pegylated interferon plus ribavirin. Currently, new forms of therapy are being developed based on a more precise knowledge of the structure and function of the viral proteins and of the strategies used by the virus to escape the immune and interferon systems. The new therapeutic approaches aim at different objectives: a) the inhibition of viral replication by blocking the viral protease and/or replicase; b) the use of other types of interferon with more potent antiviral effect, c) the induction of a specific anti-viral immune response by means of immunomodulatory compounds or therapeutic vaccination, d) the blockade of "de novo" infection of other cells with neutralizing antibodies, e) the induction of a antiviral state in the liver by transferring to this organ the gene of interferon and/or immunostimulating cytokines.

A Phase I/II Study Evaluating Escalating Doses of Recombinant Human Albumin-Interferon-α Fusion Protein in Chronic Hepatitis C Patients who have Failed Previous Interferon-α-Based Therapy

Albumin-interferon-α (IFN-α) is a novel 85.7–kDa recombinant protein consisting of IFN-α that is genetically fused to human serum albumin. In this Phase I/II, multicentre, open-label study, we evaluated the safety and tolerability, pharmacokinetics and pharmacodynamics of albumin-IFN-α in IFN-α-experienced patients with chronic hepatitis C. Albumin-IFN-α was administered in 22 escalating doses (7–900 μg) in a single injection or in two injections 14 days apart. In the 119 patients studied, there were no discontinuations because of adverse events, and albumin-IFN-α had a favourable safety profile at doses up to 900 μg. The most common adverse events were headache (56%), fatigue (52%), injection site erythema (38%), arthralgias (32%) and pyrexia (27%). Reduced clearance resulted in a mean elimination half-life of 159h, which supports dosing at 2- to 4-week intervals. Induction of the IFN-specific gene OAS1 was maintained for ≥28 days following a single injection of albumin-IFN-α at doses of ≥40 μg. Dose-dependent antiviral activity was observed in this IFN-α-experienced study population. Antiviral activity of ≥1.0–log reductions in HCV RNA was observed in 47% (37/78) of patients in the 120- to 900-μg cohorts and in 59% (16/27) in the 400- to 900-μg double-injection cohorts. These results support further clinical studies of albumin-IFN-α for the treatment of patients with chronic hepatitis C.

Review: Milstein Award lecture: interferons and cancer: where from here?

Interferons (IFNs) remain the most broadly active cytokines for cancer treatment, yet ones for which the full potential is not reached. IFNs have impacted positively on both quality and quantity of life for hundreds of thousands of cancer patients with chronic leukemia, lymphoma, bladder carcinoma, melanoma, and renal carcinoma. The role of the IFN system in malignant pathogenesis continues to enhance understanding of how the IFN system may be modulated for therapeutic advantage. Reaching the full potential of IFNs as therapeutics for cancer will also result from additional understanding of the genes underlying apoptosis induction, angiogenesis inhibition, and influence on immunologic function. Food and Drug Administration (FDA) approval of IFNs occurred less than 20 years ago; after 40 years, third-generation products of early cytotoxics, such as 5- fluorouracil (5FU), are beginning to reach clinical approval. Thus, substantial potential exists for additional application of IFNs and IFN inducers as anticancer therapeutics, particularly when one considers that their pleiotropic cellular and molecular effects have yet to be fully defined.

Preclinical safety testing of biotechnology-derived pharmaceuticals: understanding the issues and addressing the challenges

The unique and complex nature of biotechnology-derived pharmaceuticals has meant that it is often not possible to follow the conventional safety testing programs used for chemicals, and hence they are evaluated on a case-by-case basis. Nonclinical safety testing programs must be rationally designed with a strong scientific understanding of the product, including its method of manufacture, purity, sequence, structure, species specificity, pharmacological and immunological effects, and intended clinical use. This knowledge, coupled with a firm understanding of the regulatory requirements for particular product types, will ensure that the most sensitive and regulatory-compliant test systems are used to optimize the chances of gaining regulatory approval for clinical testing or marketing authorization in the shortest possible time frame.