Recombinant interferon gamma for treatment of chronic granulomatous disease and other disorders

The chemistry, biological activity, and pharmacokinetics of gamma-interferon and recombinant interferon gamma are reviewed, and the agent's clinical efficacy, adverse effects, and dosage and administration for the treatment of chronic granulomatous disease (CGD) and other disorders are described. Endogenous gamma-interferon is a 166-amino-acid protein encoded by a single gene on chromosome 12. Recombinant human interferon gamma is purified from Escherichia coli as a monomer containing 139 amino acids. Gamma-interferon has antiviral, immunomodulatory, and antiproliferative activity. Serum concentrations of recombinant interferon gamma increase in proportion to the dose. Clearance after i.m. or s.c. administration fits a two-compartment model. The half-life is 3.5-7.5 hours, and bioavailability is 89%. Evidence that recombinant interferon gamma can enhance phagocytic oxidative metabolism led to its evaluation for use in the treatment of CGD. Clinical studies showed that the agent decreases the frequency of serious infections in patients with CGD. Recombinant interferon gamma has shown only limited success in the treatment of metastatic renal cell carcinoma (RCC), both as a single agent and in combination with recombinant interferon alfa. Similarly, although interferons appear to be able to change cytogenetic abnormalities in some patients with Philadelphia chromosome-positive chronic myelogenous leukemia, therapy with recombinant interferon gamma has led to minimal success. However, the agent has produced some encouraging results in atopic dermatitis. The adverse effects of recombinant interferon gamma in patients with CGD usually consist only of fever, chills, headache, and erythema. The recommended dosage in CGD-afflicted children whose body surface area is greater than 0.5 sq m is 50 micrograms/sq m given by s.c. injection three times a week for life. Recombinant interferon gamma has given new hope to patients with CGD. Although the drug is very expensive, the cost may be offset by fewer hospitalizations to treat infection.