Controlled release recombinant human interferon-α2b for treating patients with chronic hepatitis C genotype 1: a phase 2a clinical trial

Engineering Strategies for Immunomodulatory Cytokine Therapies - Challenges and Clinical Progress

Cytokines are immunoregulatory proteins involved in many pathological states with promising potential as therapeutic agents. A diverse array of cytokines have been studied in preclinical disease models since the 1950s, some of which became successful biopharmaceutical products with the advancement of recombinant protein technology in the 1980s. However, following these early approvals, clinical translation of these natural immune signaling molecules has been limited due to their pleiotropic action in many cell types, and the fact that they have evolved to act primarily locally in tissues. These characteristics, combined with poor pharmacokinetics, have hindered the delivery of cytokines via systemic administration routes due to dose-limiting toxicities. However, given their clinical potential and recent clinical successes in cancer immunotherapy, cytokines continue to be extensively pursued in preclinical and clinical studies, and a range of molecular and formulation engineering strategies are being applied to reduce treatment toxicity while maintaining or enhancing therapeutic efficacy. This review provides a brief background on the characteristics of cytokines and their history as clinical therapeutics, followed by a deeper discussion on the engineering strategies developed for cytokine therapies with a focus on the translational relevance of these approaches.

Controlled-release interferon alpha 2b, a new member of the interferon family for the treatment of chronic hepatitis C

INTRODUCTION

Combination therapy with pegylated interferon alpha (Peg-interferon) and ribavirin is currently the cornerstone of antiviral therapy for chronic hepatitis C. Monotherapy with Peg-interferon still is important for the treatment of chronic hepatitis B. With the advent of new therapies, protease inhibitors for chronic hepatitis C and nucleotide inhibitors for chronic hepatitis B, there remains a need for interferon-based therapies. The side effects of Peg-interferon are a main disadvantage and represent a stumbling block for many patients to enter and continue therapy.

AREAS COVERED

In this review, the authors will discuss controlled-release interferon alpha 2b (CR2b) (Locteron®, Biolex Therapeutics, Pittsboro, NC, USA), a new slow-release interferon alpha 2b preparation for the treatment of chronic viral hepatitis. Other alternative interferons will also be discussed.

EXPERT OPINION

CR2b is a slow-release microsphere preparation for the administration of plant-derived recombinant human interferon alpha 2b. Compared with Peg-interferon, treatment with CR2b shows less flu-like reactions and less depression, and is at least as effective as conventional Peg-interferon-based therapy in patients with chronic hepatitis C. CR2b has the added advantage of biweekly instead of once weekly administration. CR2b appears to cause more neutropenia than Peg-interferon alpha 2b. This may be due to higher trough serum levels of CR2b at the end of a dosing interval. The bone marrow effects of CR2b closely resemble those published for the registered Peg-interferon alpha 2a. CR2b appears to have at least comparable efficacy with fewer side effects than current registered Peg-interferons.