Chandrika Govardhan

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.

Novel Long-Acting Crystal Formulation of Human Growth Hormone

PurposeThe 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.MethodsCrystals 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.ResultsHere 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.ConclusionsThe approach described here offers an exciting possibility of being broadly applicable to other therapeutic proteins.

Candida rugosa lipase: Enantioselectivity enhancements in organic solvents

Abstract Chiral resolutions of carboxylic acids ( 1–3 ) and alcohol ( 4 ) were carried out through esterification or transesterification in organic solvents using cross-linked enzyme crystals (CLEC®) of Candida rugosa lipase (CRL). Comparison of these results with those of crude CRL reveal significant differences. As was seen in resolution through hydrolysis, 1 a marked improvement in enantioselectivity is realized with the CLEC. Additionally, the stability afforded the enzyme in CLEC form leads to a higher activity in organic solvent.