Enhanced liquid formulation stability of erythropoietin alpha through purification processing

1. A method for purifying recombinant human erythropoietin alpha comprising:

a. Subjecting unpurified erythropoietin alpha manufactured from a Chinese hamster ovary cell (CHO), a baby hamster kidney fibroblasts cell (BHK), or a HeLa cell, to anion exchange chromatography; said anion exchange chromatography step comprising a wash buffer containing Urea; and collecting the resultant eluent from said anion exchange chromatography, and

b. further subjecting the resultant eluent from step a to an ammonium sulfate precipitation step having a concentration of ammonium sulfate between 3.6 M and 2.0M; filtering a precipitate from the ammonium sulfate precipitation step and collecting the resulting filtrate, and

c. further subjecting the resultant filtrate from step b to a hydrophobic interaction chromatography step and collecting the resultant eluent, and

d. further subjecting the resultant eluent from step c to an acetonitrile addition and collecting said diluent, and

e. further subjecting the resultant diluent from step d to a reversed phase chromatography step and collecting the resultant eluent, and

f. further subjecting the resultant eluent from step e to a second anion exchange chromatography step and collecting the resultant eluent, and

g. further subjecting the resultant eluent from step f to a gel filtration for buffer exchange and collecting the resulting eluent, and

h. further subjecting the resultant eluent from step g to nanofiltration for virus removal.

2. The method of claim 1 wherein the method results in a recombinant human erythropoietin alpha product that is substantially free of non-O-glycosylated recombinant human erythropoietin alpha isoforms.

3. The method of claim 1 wherein the wash buffer of step a comprises a urea concentration of 6M.

4. The method of claim 1 wherein the wash buffer of step a comprises a urea concentration of less than 3M.

5. The method of claim 1 wherein the wash buffer of step a comprises a urea concentration of less than 1M.

6. The method of claim 1 wherein the wash buffer of step a comprises a urea concentration of less than 0.1M.

7. The method of claim 1 further comprising the step of filling said product of step h into a Type 1 glass container for storage of the purified recombinant human erythropoietin alpha product.

8. The method of claim 1 , wherein a suitable fraction of the resultant eluent is collected in step e.

9. The process of claim 1 , wherein the ammonium sulfate precipitation step is filtered and the resultant filtrate from step b, is subjected to hydrophobic interaction chromatography of step c, without dilution of the filtrate from step b.

10. A multi-step process for the production of a stable recombinant human erythropoietin alpha product that is substantially free of non-O-glycosylated recombinant human erythropoietin alpha isoforms comprising the following steps:

a. Subjecting a sample comprising recombinant human erythropoietin alpha and impurities to anion exchange chromatography, utilizing wash buffer having a urea concentration of about 6M, and collecting the elute from said chromatography step, and

b. further subjecting the resultant eluent from step a to an ammonium sulfate precipitation step with a concentration of ammonium sulfate between 3.6 M and 2.0M, filtering the precipitate, and collecting the resulting filtrate, and

c. further subjecting the undiluted resultant filtrate from step b to a hydrophobic interaction chromatography step and collecting the eluent, and

d. further subjecting the resultant eluent from step c to an acetonitrile addition and collecting said diluent, and

e. further subjecting the resultant diluent from step d to a reversed phase chromatography step and collecting the eluent, and

f. further subjecting the resultant eluent from step e to a second anion exchange chromatography step and collecting the eluent, and

g. further subjecting the resultant eluent from step f to a gel filtration for buffer exchange and collecting the eluent, and

h. further subjecting the resultant eluent from step g to nanofiltration for virus removal.

11. The process of claim 10 , wherein a suitable fraction of the resultant eluent is collected in step e.