SBIR-STTR Award

IFN-alpha is widely used for the treatment of viral infections (hepatitis B and C) and cancer, but dose-limiting toxicity has prevented many patients from benefiting from this drug. The ultimate goal of the proposed project is to develop a form of IFN-alpha that retains its anti-viral and anti-cancer effects but has little or no toxicity. Of the type I IFNs, ovine IFN-tau (oIFNtau) has been shown to exhibit high antiviral and antiproliferative activity without the toxicity associated with IFN-alpha or IFN-beta. However, because of marked sequence differences between IFN-tau and human IFNs, the former is not available for human use because of its presumed immunogenicity. Nonetheless, in vitro data from recent studies comparing a synthetic hybrid of oIFNtau and human IFN-alpha suggest that the low toxicity of oIFNtau is attributable to non-conserved amino acids present within the first 27 N-terminal residues of the mature hybrid protein. We propose to identify the critical residues and insert these residues into IFN-alpha with the goal of generating a mutant form of this cytokine that lacks the toxicity of the parent molecule. Purified proteins generated from the mutant genes will be assayed for their ability to inhibit viral replication and tumor cell growth. Also, the level of cytotoxicity mediated by these proteins will be examined on a panel of normal human cells. If this project is successful, the analogs developed should be able to be used in much higher doses and with greater efficacy than native IFN-alpha.

Thesaurus Terms:
antineoplastic, antiviral agent, immunologic substance development /preparation, interferon alpha, protein engineering cytotoxicity, protein sequence protein purification

The clinically available forms of human interferon (IFN) alpha-IFNalpha2alpha (Roferon-A), IFNalpha2b (Intron). Consensus IFN and pegylated IFNs (PEG Intron and Pegasys) - are useful in the treatment of several viral diseases and cancers. However, when used at therapeutic doses they produce frequent and sometimes serious side effects, including fever, myalgia, CNS effects and leukopenia, which limit their use. IFNinterferon, a structurally related interferon in ruminants, has similar antiviral and antitumor properties as the IFNalpha's but little or no toxicity. However, as a xenoprotein IFNinterferon is not a suitable candidate for development as a parenteral drug for humans. We have synthesized an analog of human IFNalpha2b, NLVgalpha2b, which contains five amino acid substitutions at positions19, 20, 22, 24 and 27 using residues from the corresponding positions in the IFNinterferon molecule. The in vitro and in vivo data from our SBIR phase I study demonstrated that these substitutions conferred markedly reduced cellular toxicity on the resulting molecule without diminishing its antiviral and antitumor activities. In this phase II project we will advance NLVgalpha2b into preclinical development by optimizing expression of this recombinant IFN in yeast, producing pegylated as well as unpegylated preparations and subjecting them to rigorous evaluation in well established animal models. The antiviral, anticancer, immunogenicity and toxicity profiles of NLVgalpha2b will be compared with those of commercially available IFNalpha2b. If this project is successful, it should be possible to administer NLVgalpha2b to patients in higher doses than can be achieved with current IFNalpha's, resulting in improved clinical outcomes.

Thesaurus Terms:
antineoplastic, antiviral agent, drug screening /evaluation, immunologic substance development /preparation, interferon alpha cytotoxicity, gene expression, pharmacology, protein sequence hamster, protein purification, yeast