Dried blood factor composition comprising trehalose

#This invention relates to dried compositions of blood factors for reconstitution with water or aqueous solutions.

#Blood factors, particularly factor VIII and factor IX, are now the standard treatment for diseases caused by a lack of the appropriate factor, in particular haemophilia. The blood factor has generally been derived from human blood by various extraction techniques, for example as disclosed in EP-A-0083483, or by expression in genetically modified micro-organisms, for example as disclosed in EP-A-0160457 and EP-A-0182448.

#Blood factor products such as factor VIII are highly delicate, unstable proteins. They are usually supplied in the form of frozen solutions in an appropriate buffer or, more generally, as freeze-dried powders. Even the freeze-dried powders must be kept cold during storage. In order to stabilise the freeze-dried material, commercial products contain a stabilising protein, in particular human serum albumin (HSA). It has not been thought possible to prepare a dry blood factor composition which is stable at ambient temperatures and at pasteurisation temperatures (e.g. 60° C.) in the absence of HSA. However, the presence of HSA introduces considerable problems of purification since it is essential that the protein is free of viral contamination. The use of recombinant HSA to overcome these problems is expensive.

#Recombinant factor VIII was received as a deep frozen solution containing approximately 2000 to 2500 units/ml in the manufacturer's high salt buffer. The thawed solution was dialysed against a buffer solution containing 500 mM NaCl, 15 mM CaCl2 and 10 mM histidine at pH 6.8. The dialysed protein was diluted in the same buffer, but with added trehalose, to give a final concentration of 500 units per ml and 10% by weight trehalose at pH 6.8. This solution was vacuum dried in 1 ml aliquots. Vacuum was reduced step-wise from atmospheric to 4 Pa (30 mTorr) to avoid freezing the sample. The temperature of the sample was not allowed to rise above 12° C. until the formation of a foam, after which the temperature was kept below 30° C. Total drying times were 24 to 28 hours.

#The samples were stored for 0, 1.5, 3 and 6 months at 40° C. and then reconstituted in 5 ml aliquots of sterile distilled water before being tested for activity. The results are shown in the following table in comparison with a commercial freeze-dried product containing HSA. Both the test and commercial samples have a high salt content. The post-drying results show that with trehalose it is possible to dry factor VIII successfully in the absence of HSA, but that a high salt content is unsatisfactory for long term storage, even in the presence of HSA.

#Percentage of initial activity Time (months) Sample Commercial Product 0 100.0 100.0 1.5 86.8 95.3 3 75.1 71.2 6 76.6 63.6