Hyperoxaluria is reduced and nephrocalcinosis prevented with an oxalate-degrading enzyme in mice with hyperoxaluria.

BACKGROUND/AIMS: Hyperoxaluria is a major risk factor for recurrent urolithiasis and nephrocalcinosis. We tested an oral therapy with a crystalline, cross-linked formulation of oxalate-decarboxylase (OxDc-CLEC) on the reduction of urinary oxalate and decrease in the severity of kidney injury in two models: AGT1 knockout mice (AGT1KO) in which hyperoxaluria is the result of an Agxt gene deficiency, and in AGT1KO mice challenged with ethylene glycol (EG). METHODS: Four different doses of OxDc-CLEC mixed with the food, or placebo were given to AGT1KO mice (200 mg/day, n = 7) for 16 days and to EG-AGT1KO mice (5, 25, and 80 mg, n = 11) for 32 days. RESULTS: Oral therapy with 200 mg OxDc-CLEC reduced both urinary (44%) and fecal oxalate (72%) in AGT1KO mice when compared to controls. Similarly, in EG-AGT1KO mice, each of the three doses of OxDc-CLEC produced a 30-50% reduction in hyperoxaluria. A sustained urinary oxalate reduction of 40% or more in the 80 mg group led to 100% animal survival and complete prevention of nephrocalcinosis and urolithiasis. CONCLUSION: These data suggest that oral therapy with OxDc-CLEC may reduce hyperoxaluria, prevent calcium oxalate nephrocalcinosis and urolithiasis, and can represent a realistic option for the treatment of human hyperoxaluria, independent of cause.

Novel long-acting crystal formulation of human growth hormone.

PURPOSE: The aim of the study is to solve a significant challenge of extending the half-life of therapeutic proteins using crystalline biopharmaceuticals and without redesigning the molecules. METHODS: Crystals of recombinant human growth hormone were coated with a monomolecular layer of positively charged poly(arginine). The pharmacokinetics and pharmacodynamics of this poly(arginine)-coated human growth hormone crystalline formulation were determined in hypophysectomized rats and monkeys. RESULTS: Here we have demonstrated for the first time that crystals of human growth hormone coated with positively charged poly(arginine) allowed for in vivo pharmacokinetic release profiles of over several days in animal models. The efficacy of this crystalline formulation injected subcutaneously once a week was found to be equivalent to seven daily soluble injections in the standard weight gain assay using the hypophysectomized rat model and in measurement of serum insulin-like growth factor in monkeys. The nonviscous nature of the suspension facilitated easy administration through a fine, 30-gauge needle and should provide for improved patient convenience and compliance. CONCLUSIONS: The approach described here offers an exciting possibility of being broadly applicable to other therapeutic proteins.

Protein crystals for the delivery of biopharmaceuticals.

The year 2002 marked the 20th anniversary of the first successful product of modern biotechnology, the regulatory approval of recombinant insulin for biopharmaceutical applications. Insulin is also the first crystalline protein to be approved for therapeutic use. Over the past two decades, almost 150 biopharmaceuticals have gained marketing authorisation; however, insulin remains the only crystalline protein on the market. Significant research and development efforts have focused on the engineering of protein molecules, efficacy testing, model development, and protein production and characterisation. These advances have dramatically boosted the therapeutic applications of proteins, which now include treatments against acute conditions, such as cancer, cardiovascular disease and viral disease, and chronic conditions, such as diabetes, growth hormone deficiency, haemophilia, arthritis, psoriasis and Crohn's disease. Despite these successes, many challenges normally associated with biopharmaceuticals, such as poor stability and limited delivery options, remain. Protein crystals have shown significant benefits in the delivery of biopharmaceuticals to achieve high concentration, low viscosity formulation and controlled release protein delivery. This review will discuss challenges related to the broader utilisation of protein crystals in biopharmaceutical applications, as well as recent advances and valuable new directions that protein crystallisation-based technologies present.